21 CFR 870.3545 - Ventricular bypass (assist) device.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ventricular bypass (assist) device. 870.3545 Section 870.3545 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Prosthetic Devices § 870.3545 Ventricular...

Left ventricular assist devices as destination therapy: a new look at survival.

PubMed

Park, Soon J; Tector, Alfred; Piccioni, William; Raines, Edward; Gelijns, Annetine; Moskowitz, Alan; Rose, Eric; Holman, William; Furukawa, Satoshi; Frazier, O Howard; Dembitsky, Walter

2005-01-01

The REMATCH trial compared the use of left ventricular assist devices with optimal medical management for patients with end-stage heart failure. When the trial met its primary end point criteria in July 2001, left ventricular assist device therapy was shown to significantly improve survival and quality of life. With extended follow-up, 2 critical questions emerge: (1) Did these benefits persist, and (2) did outcomes improve over the course of the trial, given the evolving nature of the technology? We analyzed survival in this randomized trial by using the product-limit method of Kaplan and Meier. Changes in the benefits of therapy were analyzed by examining the effect of the enrollment period. The survival rates for patients receiving left ventricular assist devices (n = 68) versus patients receiving optimal medical management (n = 61) were 52% versus 28% at 1 year and 29% versus 13% at 2 years ( P = .008, log-rank test). As of July 2003, 11 patients were alive on left ventricular assist device support out of a total 16 survivors (including 3 patients receiving optimal medical management who crossed over to left ventricular assist device therapy). There was a significant improvement in survival for left ventricular assist device-supported patients who enrolled during the second half of the trial compared with the first half ( P = .03). The Minnesota Living with Heart Failure scores improved significantly over the course of the trial. The extended follow-up confirms the initial observation that left ventricular assist device therapy renders significant survival and quality-of-life benefits compared with optimal medical management for patients with end-stage heart failure. Furthermore, we observed an improvement in the survival of patients receiving left ventricular assist devices over the course of the trial, suggesting the effect of greater clinical experience.

Implantable physiologic controller for left ventricular assist devices with telemetry capability.

PubMed

Asgari, Siavash S; Bonde, Pramod

2014-01-01

Rotary type left ventricular assist devices have mitigated the problem of durability associated with earlier pulsatile pumps and demonstrated improved survival. However, the compromise is the loss of pulsatility due to continuous flow and retained percutaneous driveline leading to increased mortality and morbidity. Lack of pulsatility is implicated in increased gastrointestinal bleeding, aortic incompetence, and diastolic hypertension. We present a novel, wirelessly powered, ultra-compact, implantable physiologic controller capable of running a left ventricular assist device in a pulsatile mode with wireless power delivery. The schematic of our system was laid out on a circuit board to wirelessly receive power and run a left ventricular assist device with required safety and backup measures. We have embedded an antenna and wireless network for telemetry. Multiple signal processing steps and controlling algorithm were incorporated. The controller was tested in in vitro and in vivo experiments. The controller drove left ventricular assist devices continuously for 2 weeks in an in vitro setup and in vivo without any failure. Our controller is more power efficient than the current Food and Drug Administration-approved left ventricular assist device controllers. When used with electrocardiography synchronization, the controller allowed on-demand customization of operation with instantaneous flow and revolutions per minute changes, resulting in a pulsatile flow with adjustable pulse pressure. Our test results prove the system to be remarkably safe, accurate, and efficient. The unique combination of wireless powering and small footprint makes this system an ideal totally implantable physiologic left ventricular assist device system. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Comparison of Transplant Waitlist Outcomes for Pediatric Candidates Supported by Ventricular Assist Devices Versus Medical Therapy.

PubMed

Law, Sabrina P; Oron, Assaf P; Kemna, Mariska S; Albers, Erin L; McMullan, D Michael; Chen, Jonathan M; Law, Yuk M

2018-05-01

Ventricular assist devices have gained popularity in the management of refractory heart failure in children listed for heart transplantation. Our primary aim was to compare the composite endpoint of all-cause pretransplant mortality and loss of transplant eligibility in children who were treated with a ventricular assist device versus a medically managed cohort. This was a retrospective cohort analysis. Data were obtained from the Scientific Registry of Transplant Recipients. The at-risk population (n = 1,380) was less than 18 years old, either on a ventricular assist device (605 cases) or an equivalent-severity, intensively medically treated group (referred to as MED, 775 cases). None. The impact of ventricular assist devices was estimated via Cox proportional hazards regression (hazard ratio), dichotomizing 1-year outcomes to "poor" (22%: 193 deaths, 114 too sick) versus all others (940 successful transplants, 41 too healthy, 90 censored), while adjusting for conventional risk factors. Among children 0-12 months old, ventricular assist device was associated with a higher risk of poor outcomes (hazard ratio, 2.1; 95% CI, 1.5-3.0; p < 0.001). By contrast, ventricular assist device was associated with improved outcomes for ages 12-18 (hazard ratio, 0.3; 95% CI, 0.1-0.7; p = 0.003). For candidates 1-5 and 6-11 years old, there were no differences in outcomes between the ventricular assist device and MED groups (hazard ratio, 0.8 and 1.0, p = 0.43 and 0.9). The interaction between ventricular assist devices and age group was strongly significant (p < 0.001). This is a comparative study of ventricular assist devices versus medical therapy in children. Age is a significant modulator of waitlist outcomes for children with end-stage heart failure supported by ventricular assist device, with the impact of ventricular assist devices being more beneficial in adolescents.

Percutaneous Repair of Postoperative Mitral Regurgitation After Left Ventricular Assist Device Implant.

PubMed

Cork, David P; Adamson, Robert; Gollapudi, Raghava; Dembitsky, Walter; Jaski, Brian

2018-02-01

Mitral regurgitation commonly improves after implantation of a left ventricular assist device without concomitant valvular repair owing to the mechanical unloading of the left ventricle. However, the development (or persistence) of significant mitral regurgitation after implantation of a left ventricular assist device is associated with adverse clinical events. We present a case of a left ventricular assist device patient who successfully underwent a percutaneous MitraClip procedure for repair of persistent late postoperative mitral insufficiency with demonstrable clinical and hemodynamic improvement. Copyright © 2018 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Orthotopic heart transplant versus left ventricular assist device: A national comparison of cost and survival

PubMed Central

Mulloy, Daniel P.; Bhamidipati, Castigliano M.; Stone, Matthew L.; Ailawadi, Gorav; Kron, Irving L.; Kern, John A.

2012-01-01

Objectives Orthotopic heart transplantation is the standard of care for end-stage heart disease. Left ventricular assist device implantation offers an alternative treatment approach. Left ventricular assist device practice has changed dramatically since the 2008 Food and Drug Administration approval of the HeartMate II (Thoratec, Pleasanton, Calif), but at what societal cost? The present study examined the cost and efficacy of both treatments over time. Methods All patients who underwent either orthotopic heart transplantation (n = 9369) or placement of an implantable left ventricular assist device (n = 6414) from 2005 to 2009 in the Nationwide Inpatient Sample were selected. The trends in treatment use, mortality, and cost were analyzed. Results The incidence of orthotopic heart transplantation increased marginally within a 5-year period. In contrast, the annual left ventricular assist device implantation rates nearly tripled. In-hospital mortality from left ventricular assist device implantation decreased precipitously, from 42% to 17%. In-hospital mortality for orthotopic heart transplantation remained relatively stable (range, 3.8%–6.5%). The mean cost per patient increased for both orthotopic heart transplantation and left ventricular assist device placement (40% and 17%, respectively). With the observed increase in both device usage and cost per patient, the cumulative Left ventricular assist device cost increased 232% within 5 years (from $143 million to $479 million). By 2009, Medicare and Medicaid were the primary payers for nearly one half of all patients (orthotopic heart transplantation, 45%; left ventricular assist device, 51%). Conclusions Since Food and Drug Administration approval of the HeartMate II, mortality after left ventricular assist device implantation has decreased rapidly, yet has remained greater than that after orthotopic heart transplantation. The left ventricular assist device costs have continued to increase and have been

Institutional Cost Comparison Between Heart Transplants and Left Ventricular Assist Device Implantations.

PubMed

Chimanji, Neeraj; Kilic, Arman; Hasan, Ayesha; Higgins, Robert S D; Whitson, Bryan A; Kilic, Ahmet

2016-12-01

Increased numbers of end-stage heart failure patients and improved technology have led to increased use of left ventricular assist devices as a viable alternative to heart transplants. Given the current economic climate, we compared costs of heart transplant versus device placement. Medical records of patients who received heart transplants or left ventricular assist devices were cross-referenced with institutional financial data. The device cohort was limited to those receiving durable (not temporary) devices. Index admission, 1-year readmission, and overall 1-year charges were compared using standard statistical methods. Of 184 identified patients with end-stage heart failure surgical therapy, 121 received left ventricular assist devices, 43 had heart transplants, and 20 received left ventricular assist devices as bridge to heart transplant; these latter patients were excluded from our analyses. At index admission, mean charges were $863 433 ± $398 427 for device patients and $725 877 ± $488 685 for transplant patients (P = .05). One-year mean readmission rates were similar (4.65/transplant patient and 4.53/device patient; P = .94), with corresponding 1-year survival rates of 87.8% and 78.0% (P = .04). Total readmission charges during year 1 were $169 732 ± $242 366 for device patients and $201 682 ± $297 565 for transplant patients (P = .08), with corresponding overall charges at 1 year of $1 029 732 ± $450 498 and $927 559 ± $562 404 (P = .49). During the first year, heart transplant and left ventricular assist device placement have similar costs. Initial index admission costs seem to favor heart transplant, with device pump costs accounting for some of the difference. From a 1-year survival perspective, heart transplant may be more effective; however, with lack of suitable donors, left ventricular assist devices are valuable in the armamentarium of advanced heart failure surgical options.

Effect of HeartMate left ventricular assist device on cardiac autonomic nervous activity.

PubMed

Kim, S Y; Montoya, A; Zbilut, J P; Mawulawde, K; Sullivan, H J; Lonchyna, V A; Terrell, M R; Pifarré, R

1996-02-01

Clinical performance of a left ventricular assist device is assessed via hemodynamic parameters and end-organ function. This study examined effect of a left ventricular assist device on human neurophysiology. This study evaluated the time course change of cardiac autonomic activity of 3 patients during support with a left ventricular assist device before cardiac transplantation. Cardiac autonomic activity was determined by power spectral analysis of short-term heart rate variability. The heart rate variability before cardiac transplantation was compared with that on the day before left ventricular assist device implantation. The standard deviation of the mean of the R-R intervals of the electrocardiogram, an index of vagal activity, increased to 27 +/- 7 ms from 8 +/- 0.6 ms. The modulus of power spectral components increased. Low frequency (sympathetic activity) and high frequency power (vagal activity) increased by a mean of 9 and 22 times of each baseline value (low frequency power, 5.2 +/- 3.0 ms2; high frequency power, 2.1 +/- 0.7 ms2). The low over high frequency power ratio decreased substantially, indicating an improvement of cardiac sympatho-vagal balance. The study results suggest that left ventricular assist device support before cardiac transplantation may exert a favorable effect on cardiac autonomic control in patients with severe heart failure.

NASA Worldwide Emergency Medical Assistance

NASA Technical Reports Server (NTRS)

Martin, George A.; Tipton, David A.; Long, Irene D.

1997-01-01

In an effort to maintain employee health and welfare, ensure customer satisfaction, and to deliver high quality emergency medical care when necessary to employees located overseas, NASA has instituted a new contract with International SOS Assistance INC. International SOS Assistance INC. will provide civil servants and contractors engaged in official NASA business with many services upon request during a medical or personal emergency. Through the years, International SOS Assistance INC. has developed the expertise necessary to provide medical service in all remote areas of the world. One phone call connects you to the SOS network of multilingual staff trained to help resolve travel, medical, legal, and security problems. The SOS network of critical care and aeromedical specialists operates 24 hours a day, 365 days a year from SOS Alarm Centers around the world. This exhibit illustrates the details of the NASA-International SOS Assistance INC. agreement.

High-Intensity Interval Training for Severe Left Ventricular Dysfunction Treated with Left Ventricular Assist Device.

PubMed

Ugata, Yusuke; Wada, Hiroshi; Sakakura, Kenichi; Ibe, Tatsuro; Ito, Miyuki; Ikeda, Nahoko; Fujita, Hideo; Momomura, Shin-Ichi

2018-01-27

Aerobic training based on anaerobic threshold (AT) is well-known to improve cardiac function, exercise capacity, and long-term outcomes of patients with heart failure. Recent reports suggested that high-intensity interval training (HIIT) for patients with cardiovascular disease may improve cardiopulmonary exercise capacity. We present a 61-year-old male patient of severe left ventricular dysfunction with left ventricular assisted device (LVAD). Following HIIT for 8 weeks, exercise capacity and muscle strength have improved without worsening left ventricular function. Our case showed the possibility that HIIT was feasible and effective even in patients with LVAD.

Development of an implantable ventricular assist system.

PubMed

Macris, M P; Parnis, S M; Frazier, O H; Fuqua, J M; Jarvik, R K

1997-02-01

This study describes the present state of progress in the development of the Jarvik 2000 ventricular assist system. Designed for implantation in the human thorax, the system consists of a small (25 cm3, 90 g) intraventricular axial-flow blood pump that transmits power and data via internal electronics and a transcutaneous energy transfer system. The pump is powered by portable internal and external polymer lithium ion batteries. The only moving part, the pump rotor, contains a permanent magnet of a brushless direct-current motor that mounts an axial-flow impeller and partial magnetic thrust support, with blood-immersed radial and thrust bearings. The motor uses a redundant coil and electric lead design, which permits continued operation in case of wire breakage. Seven calves have been supported for an average of 107 days (range, 40 to 162 days) with prototypes of the Jarvik 2000 ventricular assist system. No physiologic complications have occurred. When its user is at rest, the pump produces flows of 5 to 6 L/min with a decreased arterial pulse contour. Renal and hepatic functions have remained normal throughout the duration of all studies. Mean plasma free hemoglobin levels ranged from 4.3 to 11.4 mg/dL (mean, 6.3 mg/dL) for each study. Pathologic analyses of the heart and kidneys revealed no damage related to the device. These studies indicate that the Jarvik 2000 ventricular assist system is feasible in animals and holds promise for long-term support of patients.

Ventricular fibrillation in an ambulatory patient supported by a left ventricular assist device: highlighting the ICD controversy.

PubMed

Boilson, Barry A; Durham, Lucian A; Park, Soon J

2012-01-01

Left ventricular assist devices (LVADs) provide an effective means of managing advanced pump failure as a means of bridging to cardiac transplantation or as permanent therapy. Although ventricular arrhythmias remain common post-LVAD implantation, such therapy may allow malignant arrhythmias to be tolerated hemodynamically. This report describes the clinical findings in a patient who had likely been in a ventricular tachyarrhythmia for several days and presented in ventricular fibrillation, ambulatory, and mentating normally. This report, with previous similar reports, is additive to the body of evidence that LVADs alter the physiologic impact of ventricular arrhythmias in advanced heart failure and highlights the need for thoughtful programming of implantable cardioverter defibrillator therapies in these patients.

Noninvasive estimation of assist pressure for direct mechanical ventricular actuation

NASA Astrophysics Data System (ADS)

An, Dawei; Yang, Ming; Gu, Xiaotong; Meng, Fan; Yang, Tianyue; Lin, Shujing

2018-02-01

Direct mechanical ventricular actuation is effective to reestablish the ventricular function with non-blood contact. Due to the energy loss within the driveline of the direct cardiac compression device, it is necessary to acquire the accurate value of assist pressure acting on the heart surface. To avoid myocardial trauma induced by invasive sensors, the noninvasive estimation method is developed and the experimental device is designed to measure the sample data for fitting the estimation models. By examining the goodness of fit numerically and graphically, the polynomial model presents the best behavior among the four alternative models. Meanwhile, to verify the effect of the noninvasive estimation, the simplified lumped parameter model is utilized to calculate the pre-support and the post-support left ventricular pressure. Furthermore, by adjusting the driving pressure beyond the range of the sample data, the assist pressure is estimated with the similar waveform and the post-support left ventricular pressure approaches the value of the adult healthy heart, indicating the good generalization ability of the noninvasive estimation method.

Animal trials of a Magnetically Levitated Left-Ventricular Assist Device

NASA Technical Reports Server (NTRS)

Paden, Brad; Antaki, James; Groom, Nelson

2000-01-01

The University of Pittsburgh/Magnetic Moments mag-lev left-ventricular assist devices (LVADs), the Streamliner HG3b and HG3c, have successfully been implanted in calves. The first was implanted for 4 hours on July 10, 1998 and the second for 34 days on August 24, 1999 respectively. The tests confirmed the feasibility of low power levitation (1.5 watts coil power) and very low blood damage in a mag-lev ventricular assist device. In this paper, we describe the unique geometry of this pump and its design. Key features of this LVAD concept are the passive radial suspension and active voice-coil thrust bearing.

Chronic outpatient management of patients with a left ventricular assist device

PubMed Central

Franzwa, Jennifer

2015-01-01

The use of mechanical circulatory support (MCS) as treatment for advanced heart failure (HF) has grown exponentially over the past 15 years. The continuous flow left ventricular assist device (CF-LVAD) has become the most used form of MCS in advanced HF, especially since approval of use as destination therapy (DT) and with the lack of organ availability. Long-term survival has improved and diligent outpatient management is thus particularly critical to achieve optimal outcomes. This review will discuss outpatient management strategies for patients with HF and a left ventricular assist device (LVAD). PMID:26793331

Inhaled Milrinone After Left Ventricular Assist Device Implantation.

PubMed

Haglund, Nicholas A; Burdorf, Adam; Jones, Tara; Shostrom, Valerie; Um, John; Ryan, Timothy; Shillcutt, Sasha; Fischer, Patricia; Cox, Zachary L; Raichlin, Eugenia; Anderson, Daniel R; Lowes, Brian D; Dumitru, Ioana

2015-10-01

Proven strategies to reduce right ventricular (RV) dysfunction after continuous-flow left ventricular assist device (CF-LVAD) implantation are lacking. We sought to evaluate the tolerability, feasibility, efficacy, and pharmacokinetics of inhaled milrinone (iMil) delivery after CF-LVAD implantation. We prospectively evaluated fixed-dose nebulized iMil delivered into a ventilator circuit for 24 hours in 10 postoperative CF-LVAD (Heartmate-II) patients. Tolerability (arrhythmias, hypotension, and hypersensitivity reaction), efficacy (hemodynamics), pharmacokinetics (plasma milrinone levels), and cost data were collected.Mean age was 56 ± 9 years, 90% were male, and mean INTERMACS profile was 2.5 ± 0.8. No new atrial arrhythmia events occurred, although 3 (30%) ventricular tachycardia (1 nonsustained, 2 sustained) events occurred. Sustained hypotension, drug hypersensitivity, death, or need for right ventricular assist device were not observed. Invasive mean pulmonary arterial pressure from baseline to during iMil therapy was improved (P = .017). Mean plasma milrinone levels (ng/mL) at baseline, and 1, 4, 8, 12, and 24 hours were 74.2 ± 35.4, 111.3 ± 70.9, 135.9 ± 41.5, 205.0 ± 86.7, 176.8 ± 61.3 187.6 ± 105.5, respectively. Reduced institutional cost was observed when iMil was compared with nitric oxide therapy over 24 hours ($165.29 vs $1,944.00, respectively). iMil delivery after CF-LVAD implantation was well tolerated, feasible, and demonstrated favorable hemodynamic, pharmacokinetic, and cost profiles. iMil therapy warrants further study in larger clinical trials. Copyright © 2015 Elsevier Inc. All rights reserved.

Management of severe ischemic cardiomyopathy: left ventricular assist device as destination therapy versus conventional bypass and mitral valve surgery.

PubMed

Maltais, Simon; Tchantchaleishvili, Vahtang; Schaff, Hartzell V; Daly, Richard C; Suri, Rakesh M; Dearani, Joseph A; Topilsky, Yan; Stulak, John M; Joyce, Lyle D; Park, Soon J

2014-04-01

Patients with severe ischemic cardiomyopathy (left ventricular ejection fraction <25%) and severe ischemic mitral regurgitation have a poor survival with medical therapy alone. Left ventricular assist device as destination therapy is reserved for patients who are too high risk for conventional surgery. We evaluated our outcomes with conventional surgery within this population and the comparative effectiveness of these 2 therapies. We identified patients who underwent conventional surgery or left ventricular assist device as destination therapy for severe ischemic cardiomyopathy (left ventricular ejection fraction <25%) and severe mitral regurgitation. The era for conventional surgery spanned from 1993 to 2009 and from 2007 to 2011 for left ventricular assist device as destination therapy. We compared baseline patient characteristics and outcomes in terms of end-organ function and survival. A total of 88 patients were identified; 55 patients underwent conventional surgery (63%), and 33 patients (37%) received a left ventricular assist device as destination therapy. Patients who received left ventricular assist device as destination therapy had the increased prevalence of renal failure, inotrope dependency, and intra-aortic balloon support. Patients undergoing conventional surgery required longer ventilatory support, and patients receiving a left ventricular assist device required more reoperation for bleeding. Mortality rates were similar between the 2 groups at 30 days (7% in the conventional surgery group vs 3% in the left ventricular assist device as destination therapy group, P = .65) and at 1 year (22% in the conventional surgery group vs 15% in the left ventricular assist device as destination therapy group, P = .58). There was a trend toward improved survival in patients receiving a left ventricular assist device compared with the propensity-matched groups at 1 year (94% vs 71%, P = .171). The operative mortality and early survival after conventional

Left ventricular assist device and drug therapy for the reversal of heart failure.

PubMed

Birks, Emma J; Tansley, Patrick D; Hardy, James; George, Robert S; Bowles, Christopher T; Burke, Margaret; Banner, Nicholas R; Khaghani, Asghar; Yacoub, Magdi H

2006-11-02

In patients with severe heart failure, prolonged unloading of the myocardium with the use of a left ventricular assist device has been reported to lead to myocardial recovery in small numbers of patients for varying periods of time. Increasing the frequency and durability of myocardial recovery could reduce or postpone the need for subsequent heart transplantation. We enrolled 15 patients with severe heart failure due to nonischemic cardiomyopathy and with no histologic evidence of active myocarditis. All had markedly reduced cardiac output and were receiving inotropes. The patients underwent implantation of left ventricular assist devices and were treated with lisinopril, carvedilol, spironolactone, and losartan to enhance reverse remodeling. Once regression of left ventricular enlargement had been achieved, the beta2-adrenergic-receptor agonist clenbuterol was administered to prevent myocardial atrophy. Eleven of the 15 patients had sufficient myocardial recovery to undergo explantation of the left ventricular assist device a mean (+/-SD) of 320+/-186 days after implantation of the device. One patient died of intractable arrhythmias 24 hours after explantation; another died of carcinoma of the lung 27 months after explantation. The cumulative rate of freedom from recurrent heart failure among the surviving patients was 100% and 88.9% 1 and 4 years after explantation, respectively. The quality of life as assessed by the Minnesota Living with Heart Failure Questionnaire score at 3 years was nearly normal. Fifty-nine months after explantation, the mean left ventricular ejection fraction was 64+/-12%, the mean left ventricular end-diastolic diameter was 59.4+/-12.1 mm, the mean left ventricular end-systolic diameter was 42.5+/-13.2 mm, and the mean maximal oxygen uptake with exercise was 26.3+/-6.0 ml per kilogram of body weight per minute. In this single-center study, we found that sustained reversal of severe heart failure secondary to nonischemic cardiomyopathy

What the Psychiatrist Needs to Know About Ventricular Assist Devices: A Comprehensive Review.

PubMed

Caro, Mario A; Rosenthal, Julie L; Kendall, Kay; Pozuelo, Leopoldo; Funk, Margo C

2016-01-01

The number of patients with end-stage heart failure using mechanical circulatory support has dramatically increased over the past decade. Left ventricular assist devices, the most common type of mechanical circulatory support, can be used as a bridge to transplant, destination therapy, and as a bridge to recovery. As this patient population continues to grow, consultation-liaison psychiatrists will become increasingly involved in their care. A thorough biopsychosocial assessment is required to ensure adequate recognition and management of medical, psychiatric, social, and ethical challenges posed by this population. We performed a literature review to identify key issues relevant to the practice of consultation-liaison psychiatrists. General functioning of left ventricular assist devices, device types, system components, life with a left ventricular assist device, preoperative evaluation, treatment of psychiatric comorbidities, and end-of-life decision-making are discussed. Consultation-liaison psychiatrists need to be familiar with the high prevalence of psychopathology in patients implanted with left ventricular assist devices. A detailed biopsychosocial formulation is required to adequately identify and, if possible, resolve a myriad of medical, psychiatric, social, and ethical challenges presented by this population. Future efforts should accurately identify and report specific psychiatric disorders and adverse events within this cohort. Copyright © 2016 The Academy of Psychosomatic Medicine. Published by Elsevier Inc. All rights reserved.

Hemodynamics on abrupt stoppage of centrifugal pumps during left ventricular assist.

PubMed

Kono, S; Nishimura, K; Nishina, T; Akamatsu, T; Komeda, M

2000-01-01

A magnetically suspended centrifugal pump (MSCP), developed for long-term ventricular assist, is reliable and durable because it has no shaft or seal. However, with nonvalve pumps such as a MSCP, regurgitation occurs when they accidentally stop without cannula clamping. We investigated the hemodynamics during temporary stoppage of a MSCP being used as a left ventricular assist system (LVAS), comparing two inflow cannulation sites. In four sheep (weight, 35-45 kg), microspheres were injected into the left main coronary artery to induce heart failure. An outflow cannula was sutured onto the descending aorta, and two inflow cannulae were inserted into the left atrium and the left ventricle. The MSCP was stopped with both the left ventricular cannula and left atrial cannula clamped, and the hemodynamics and P-V loops were recorded. Each cannula was then unclamped in order, and similar parameters were recorded. LVEDP increased at unclamping of the left ventricular cannula (ULVC), and rose further at unclamping of the left atrial cannula (ULAC). Aortic pressure did not change at ULVC, but decreased at ULAC. The effective systemic flow that subtracted the regurgitant flow through the MSCP from left ventricular output was half at ULVC and almost 0 at ULAC. When stopping centrifugal pumps without circuit clamping, hemodynamic deterioration is less at ULVC than at ULAC. This finding suggests that left ventricular inflow cannulation is recommended to allow more time in emergency situations.

Central-Approach Surgical Repair of Coarctation of the Aorta with a Back-up Left Ventricular Assist Device for an Infant Presenting with Severe Left Ventricular Dysfunction.

PubMed

Kim, Tae Hoon; Shin, Yu Rim; Kim, Young Sam; Kim, Do Jung; Kim, Hyohyun; Shin, Hong Ju; Htut, Aung Thein; Park, Han Ki

2015-12-01

A two-month-old infant presented with coarctation of the aorta, severe left ventricular dysfunction, and moderate to severe mitral regurgitation. Through median sternotomy, the aortic arch was repaired under cardiopulmonary bypass and regional cerebral perfusion. The patient was postoperatively supported with a left ventricular assist device for five days. Left ventricular function gradually improved, eventually recovering with the concomitant regression of mitral regurgitation. Prompt surgical repair of coarctation of the aorta is indicated for patients with severe left ventricular dysfunction. A central approach for surgical repair with a back-up left ventricular assist device is a safe and effective treatment strategy for these patients.

Intraoperative Transesophageal Echocardiography and Right Ventricular Failure After Left Ventricular Assist Device Implantation.

PubMed

Silverton, Natalie A; Patel, Ravi; Zimmerman, Josh; Ma, Jianing; Stoddard, Greg; Selzman, Craig; Morrissey, Candice K

2018-02-15

To determine whether intraoperative measures of right ventricular (RV) function using transesophageal echocardiography are associated with subsequent RV failure after left ventricular assist device (LVAD) implantation. Retrospective, nonrandomized, observational study. Single tertiary-level, university-affiliated hospital. The study comprised 100 patients with systolic heart failure undergoing elective LVAD implantation. Transesophageal echocardiographic images before and after cardiopulmonary bypass were analyzed to quantify RV function using tricuspid annular plane systolic excursion (TAPSE), tricuspid annular systolic velocity (S'), fractional area change (FAC), RV global longitudinal strain, and RV free wall strain. A chart review was performed to determine which patients subsequently developed RV failure (right ventricular assist device placement or prolonged inotrope requirement ≥14 days). Nineteen patients (19%) subsequently developed RV failure. Postbypass FAC was the only measure of RV function that distinguished between the RV failure and non-RV failure groups (21.2% v 26.5%; p = 0.04). The sensitivity, specificity, and area under the curve of an abnormal RV FAC (<35%) for RV failure after LVAD implantation were 84%, 20%, and 0.52, respectively. No other intraoperative measure of RV function was associated with subsequent RV failure. RV failure increased ventilator time, intensive care unit and hospital length of stay, and mortality. Intraoperative measures of RV function such as tricuspid annular plane systolic excursion, tricuspid annular systolic velocity, and RV strain were not associated with RV failure after LVAD implantation. Decreased postbypass FAC was significantly associated with RV failure but showed poor discrimination. Copyright © 2018 Elsevier Inc. All rights reserved.

Right ventricular functional analysis utilizing first pass radionuclide angiography for pre-operative ventricular assist device planning: a multi-modality comparison.

PubMed

Avery, Ryan; Day, Kevin; Jokerst, Clinton; Kazui, Toshinobu; Krupinski, Elizabeth; Khalpey, Zain

2017-10-10

Advanced heart failure treated with a left ventricular assist device is associated with a higher risk of right heart failure. Many advanced heart failures patients are treated with an ICD, a relative contraindication to MRI, prior to assist device placement. Given this limitation, left and right ventricular function for patients with an ICD is calculated using radionuclide angiography utilizing planar multigated acquisition (MUGA) and first pass radionuclide angiography (FPRNA), respectively. Given the availability of MRI protocols that can accommodate patients with ICDs, we have correlated the findings of ventricular functional analysis using radionuclide angiography to cardiac MRI, the reference standard for ventricle function calculation, to directly correlate calculated ejection fractions between these modalities, and to also assess agreement between available echocardiographic and hemodynamic parameters of right ventricular function. A retrospective review from January 2012 through May 2014 was performed to identify advanced heart failure patients who underwent both cardiac MRI and radionuclide angiography for ventricular functional analysis. Nine heart failure patients (8 men, 1 woman; mean age of 57.0 years) were identified. The average time between the cardiac MRI and radionuclide angiography exams was 38.9 days (range: 1 - 119 days). All patients undergoing cardiac MRI were scanned using an institutionally approved protocol for ICD with no device-related complications identified. A retrospective chart review of each patient for cardiomyopathy diagnosis, clinical follow-up, and echocardiogram and right heart catheterization performed during evaluation was also performed. The 9 patients demonstrated a mean left ventricular ejection fraction (LVEF) using cardiac MRI of 20.7% (12 - 40%). Mean LVEF using MUGA was 22.6% (12 - 49%). The mean right ventricular ejection fraction (RVEF) utilizing cardiac MRI was 28.3% (16 - 43%), and the mean RVEF calculated by

Association of HeartMate II left ventricular assist device flow estimate with thermodilution cardiac output.

PubMed

Hasin, Tal; Huebner, Marianne; Li, Zhuo; Brown, Daniel; Stulak, John M; Boilson, Barry A; Joyce, Lyle; Pereira, Naveen L; Kushwaha, Sudhir S; Park, Soon J

2014-01-01

Cardiac output (CO) assessment is important in treating patients with heart failure. Durable left ventricular assist devices (LVADs) provide essentially all CO. In currently used LVADs, estimated device flow is generated by a computerized algorithm. However, LVAD flow estimate may be inaccurate in tracking true CO. We correlated LVAD (HeartMate II) flow with thermodilution CO during postoperative care (day 2-10 after implant) in 81 patients (5,616 paired measurements). Left ventricular assist device flow and CO correlated with a low correlation coefficient (r = 0.42). Left ventricular assist device readings were lower than CO measurements by approximately 0.36 L/min, trending for larger difference with higher values. Left ventricular assist device flow measurements showed less temporal variability compared with CO. Grouping for simultaneous measured blood pressure (BP < 60, 60-70, 70-80, 80-90, and ≥90), the correlation of CO with LVAD flow differed (R = 0.42, 0.67, 0.48, 0.32, 0.32, respectively). Indicating better correlation when mean blood pressure is 60 to 70 mm Hg. Left ventricular assist device flow generally trends with measured CO, but large variability exists, hence flow measures should not be assumed to equal with CO. Clinicians should take into account variables such as high CO, BP, and opening of the aortic valve when interpreting LVAD flow readout. Direct flow sensors incorporated in the LVAD system may allow for better estimation.

Outcomes of patients with right ventricular failure on milrinone after left ventricular assist device implantation.

PubMed

Tsiouris, Athanasios; Paone, Gaetano; Brewer, Robert J; Nemeh, Hassan W; Borgi, Jamil; Morgan, Jeffrey A

2015-01-01

Previous studies have grouped together both patients requiring right ventricular assist devices (RVADs) with patients requiring prolonged milrinone therapy after left ventricular assist device (LVAD) implantation. We retrospectively identified 149 patients receiving LVADs and 18 (12.1%) of which developed right ventricular (RV) failure. We then separated these patients into those requiring RVADs versus prolonged milrinone therapy. This included 10 patients who were treated with prolonged milrinone and eight patients who underwent RVAD placement. Overall, the RV failure group had worse survival compared with the non-RV failure cohort (p = 0.038). However, this was only for the subgroup of patients who required RVADs, who had a 1, 6, 12, and 24 month survival of 62.5%, 37.5%, 37.5%, and 37.5%, respectively, versus 96.8%, 92.1%, 86.7%, and 84.4% for patients without RV failure (p < 0.001). Patients treated with prolonged milrinone therapy for RV failure had similar survivals compared with patients without RV failure. In the RV failure group, age, preoperative renal failure, and previous cardiac surgery were predictors of the need for prolonged postoperative milrinone. As LVADs become a more widely used therapy for patients with refractory, end-stage heart failure, it will be important to reduce the incidence of RV failure, as it yields significant morbidity and increases cost.

Bridge to Removal: A Paradigm Shift for Left Ventricular Assist Device Therapy

PubMed Central

Selzman, Craig H.; Madden, Jesse L.; Healy, Aaron H.; McKellar, Stephen H.; Koliopoulou, Antigone; Stehlik, Josef; Drakos, Stavros G.

2014-01-01

Ventricular assist devices have become standard therapy for patients with advanced heart failure either as a bridge to transplantation or destination therapy. Despite the functional and biologic evidence of reverse cardiac remodeling, few patients actually proceed to myocardial recovery, and even fewer to the point of having their device explanted. An enhanced understanding of the biology and care of the mechanically supported patient has redirected focus on the possibility of using ventricular assist devices as a bridge to myocardial recovery and removal. Herein, we review the current issues and approaches to transforming myocardial recovery to a practical reality. PMID:25442985

Performance Improvement to Decrease Readmission Rates for Patients With a Left Ventricular Assist Device.

PubMed

Iseler, Jackeline; Fox, John; Wierenga, Kelly

2018-06-01

The 30-day readmission rate for patients with a left ventricular assist device implantation at a large, urban, Midwest hospital system (from October 2013 to September 2014) was estimated at 32.1%. Readmission rates were a concern at this facility. Review of the readmissions, change in practice, and home expectations of patients and families have identified an opportunity to improve the transitions of care for this left ventricular assist device (LVAD) program. Therefore, the purpose of this project was to evaluate the effectiveness and feasibility of a transitional care model (TCM) for care of patients with left ventricular devices. Ten patients were enrolled in the pilot that was implemented in June 2015. A transitional care nurse trained to support patients with ventricular assist devices was used to facilitate patient flow. The goal was to create an individualized plan for the development or improvement of self-management skills to decrease readmission rates. The transitional care nurse collaborated with the ventricular device team. The 30-day readmission rate during the pilot was 14.3% compared to the previous annual overall rate of 42.6%. Based on these results, further research is recommended into interventions consistent with the TCM to advance care coordination and to facilitate care transition in the this fragile patient population.

Durability of central aortic valve closure in patients with continuous flow left ventricular assist devices.

PubMed

McKellar, Stephen H; Deo, Salil; Daly, Richard C; Durham, Lucian A; Joyce, Lyle D; Stulak, John M; Park, Soon J

2014-01-01

A competent aortic valve is essential to providing effective left ventricular assist device support. We have adopted a practice of central aortic valve closure by placing a simple coaptation stitch at left ventricular assist device implantation in patients with significant aortic insufficiency. We conducted a follow-up study to evaluate the efficacy and durability of this procedure. The study included patients who had undergone continuous flow left ventricular assist device implantation. The patients were divided into 2 groups, those who did not require any aortic procedure because the valve was competent and those who underwent central aortic valve closure for mild or greater aortic regurgitation. The clinical endpoints were mortality, progression or recurrence of aortic insufficiency, and reoperation for aortic valve pathologic features. Aortic insufficiency was measured qualitatively from mild to severe on a scale of 0 to 5. A total of 123 patients received continuous flow left ventricular assist devices from February 2007 to August 2011. Of those, 18 (15%) underwent central aortic valve closure at left ventricular assist device implantation because of significant aortic insufficiency (1.8 ± 1.4) and 105 who did not (competent aortic valve, 0.15 ± 0.43; P < .01). At follow-up (median, 312 days; range, 0-1429 days), the mean aortic insufficiency score remained low for the patients with central aortic valve closure (0.27 ± 0.46) in contrast to those without central aortic valve closure who experienced aortic insufficiency progression (0.78 ± 0.89; P = .02). In addition, the proportion of patients with more than mild aortic insufficiency was significantly less in the central aortic valve closure group (0% vs 18%; P = .05). The patients in the central aortic valve closure group were significantly older and had a greater incidence of renal failure at baseline. The 30-day mortality was greater in the central aortic valve closure group, but the late survival

Wave Intensity Analysis of Right Ventricular Function during Pulsed Operation of Rotary Left Ventricular Assist Devices.

PubMed

Bouwmeester, J Christopher; Park, Jiheum; Valdovinos, John; Bonde, Pramod

2018-05-29

Changing the speed of left ventricular assist devices (LVADs) cyclically may be useful to restore aortic pulsatility; however, the effects of this pulsation on right ventricular (RV) function are unknown. This study investigates the effects of direct ventricular interaction by quantifying the amount of wave energy created by RV contraction when axial and centrifugal LVADs are used to assist the left ventricle. In 4 anesthetized pigs, pressure and flow were measured in the main pulmonary artery and wave intensity analysis was used to identify and quantify the energy of waves created by the RV. The axial pump depressed the intensity of waves created by RV contraction compared with the centrifugal pump. In both pump designs, there were only minor and variable differences between the continuous and pulsed operation on RV function. The axial pump causes the RV to contract with less energy compared with a centrifugal design. Diminishing the ability of the RV to produce less energy translates to less pressure and flow produced, which may lead to LVAD-induced RV failure. The effects of pulsed LVAD operation on the RV appear to be minimal during acute observation of healthy hearts. Further study is necessary to uncover the effects of other modes of speed modulation with healthy and unhealthy hearts to determine if pulsed operation will benefit patients by reducing LVAD complications.

Successful weaning of a left ventricular assist device implanted for ischemic heart failure.

PubMed

Beurtheret, Sylvain; Mordant, Pierre; Pavie, Alain; Leprince, Pascal

2010-10-01

We report the case of a patient stabilized under extra-corporeal membrane oxygenation after a refractory cardiogenic shock following myocardial infarction. Persistent left ventricular failure required secondary implantation of the left ventricular assist device (LVAD) HeartMate II. LVAD succeeded in the gradual recovery of myocardial contractility, allowing weaning of the device five months after implantation. Simultaneously, the patient beneficiated from coronary revascularization and resumed normal activity. This case emphasizes potential late recoveries after myocardial infarction complicated by left ventricular failure.

Left Ventricular Assist Devices: The Adolescence of a Disruptive Technology.

PubMed

Pinney, Sean P

2015-10-01

Clinical outcomes for patients with advanced heart failure receiving left ventricular assist devices are driven by appropriate patient selection, refined surgical technique, and coordinated medical care. Perhaps even more important is innovative pump design. The introduction and widespread adoption of continuous-flow ventricular assist devices has led to a paradigm shift within the field of mechanical circulatory support, making the promise of lifetime device therapy closer to reality. The disruption caused by this new technology, on the one hand, produced meaningful improvements in patient survival and quality of life, but also introduced new clinical challenges, such as bleeding, pump thrombosis, and acquired valvular heart disease. Further evolution within this field will require financial investment to sustain innovation leading to a fully implantable, durable, and cost-effective pump for a larger segment of patients with advanced heart failure. Copyright © 2015 Elsevier Inc. All rights reserved.

App-assisted external ventricular drain insertion.

PubMed

Eftekhar, Behzad

2016-09-01

The freehand technique for insertion of an external ventricular drain (EVD) is based on fixed anatomical landmarks and does not take individual variations into consideration. A patient-tailored approach based on augmented-reality techniques using devices such as smartphones can address this shortcoming. The Sina neurosurgical assist (Sina) is an Android mobile device application (app) that was designed and developed to be used as a simple intraoperative neurosurgical planning aid. It overlaps the patient's images from previously performed CT or MRI studies on the image seen through the device camera. The device is held by an assistant who aligns the images and provides information about the relative position of the target and EVD to the surgeon who is performing EVD insertion. This app can be used to provide guidance and continuous monitoring during EVD placement. The author describes the technique of Sina-assisted EVD insertion into the frontal horn of the lateral ventricle and reports on its clinical application in 5 cases as well as the results of ex vivo studies of ease of use and precision. The technique has potential for further development and use with other augmented-reality devices.

Mycobacterium chimaera left ventricular assist device infections.

PubMed

Balsam, Leora B; Louie, Eddie; Hill, Fred; Levine, Jamie; Phillips, Michael S

2017-06-01

A global outbreak of invasive Mycobacterium chimaera infections after cardiac surgery has recently been linked to bioaerosols from contaminated heater-cooler units. The majority of cases have occurred after valvular surgery or aortic graft surgery and nearly half have resulted in death. To date, infections in patients with left ventricular assist devices (LVADs) have not been characterized in the literature. We report two cases of device-associated M. chimaera infection in patients with continuous-flow LVADs and describe challenges related to diagnosis and management in this population. © 2017 Wiley Periodicals, Inc.

The Achilles' heel of left ventricular assist device therapy: right ventricle.

PubMed

Ranganath, Neel K; Smith, Deane E; Moazami, Nader

2018-06-01

Many patients suffer from either persistent right ventricular failure (RVF) at the time of left ventricular assist device (LVAD) or have ongoing symptoms consistent with RVF during chronic mechanical circulatory support. The lack of long-term right ventricular assist devices (RVADs) has limited the impact that mechanical circulatory support can provide to patients with biventricular failure. We aim to review the entire spectrum of RVF in patients receiving LVADs and reflect on why this entity remains the Achilles' heel of LVAD therapy. In the early postoperative period, LVAD implantation reduces right ventricle (RV) afterload, but RV dysfunction may be exacerbated secondary to increased venous return. With prolonged therapy, the decreased RV afterload leads to improved RV contractile function. Bayesian statistical models outperform previously published preoperative risk scores by considering inter-relationships and conditional probabilities amongst independent variables. Various echocardiographic parameters and the pulmonary artery pulsatility index have shown promise in predicting post-LVAD RVF. Recent publications have delineated the emergence of 'delayed' RVF. Several devices are currently being investigated for use as RVADs. Post-LVAD RVF depends on the RV's ability to adapt to acute hemodynamic changes imposed by the LVAD. Management options are limited due to the lack of an easily implantable, chronic-use RVAD.

Detection of premature ventricular contractions on a ventricular electrocardiogram for patients with left ventricular assist devices.

PubMed

Park, Sung Min; Lee, Jin Hong; Choi, Seong Wook

2014-12-01

The ventricular electrocardiogram (v-ECG) was developed for long-term monitoring of heartbeats in patients with a left ventricular assist device (LVAD) and does not normally have the functionality necessary to detect additional heart irregularities that can progress to critical arrhythmias. Although the v-ECG has the benefits of physiological optimization and counterpulsation control, when abnormal heartbeats occur, the v-ECG does not show the distinct abnormal waveform that enables easy detection of an abnormal heartbeat among normal heartbeats on the conventional ECG. In this study, the v-ECGs of normal and abnormal heartbeats are compared with each other with respect to peak-to-peak voltage, area, and maximal slopes, and a new method to detect abnormal heartbeats is suggested. In a series of animal experiments with three porcine models (Yorkshire pigs weighing 30-40 kg), a v-ECG and conventional ECG were taken simultaneously during LVAD perfusion. Clinical experts found 104 abnormal heartbeats from the saved conventional ECG data and confirmed that the other 3159 heartbeats were normal. Almost all of the abnormal heartbeats were premature ventricular contractions (PVCs), and there was short-term tachycardia for 3 s. A personal computer was used to automatically detect abnormal heartbeats with the v-ECG according to the new method, and its results were compared with the clinicians' results. The new method found abnormal heartbeats with 90% accuracy, and less than 15% of the total PVCs were missed. Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

The Use of Pediatric Ventricular Assist Devices in Children's Hospitals From 2000 to 2010: Morbidity, Mortality, and Hospital Charges.

PubMed

Mansfield, Robert T; Lin, Kimberly Y; Zaoutis, Theoklis; Mott, Antonio R; Mohamad, Zeinab; Luan, Xianqun; Kaufman, Beth D; Ravishankar, Chitra; Gaynor, J William; Shaddy, Robert E; Rossano, Joseph W

2015-07-01

The use of ventricular assist devices has increased dramatically in adult heart failure patients. However, the overall use, outcome, comorbidities, and resource utilization of ventricular assist devices in pediatric patients have not been well described. We sought to demonstrate that the use of ventricular assist devices in pediatric patients has increased over time and that mortality has decreased. A retrospective study of the Pediatric Health Information System database was performed for patients 20 years old or younger undergoing ventricular assist device placement from 2000 to 2010. None. Four hundred seventy-five pediatric patients were implanted with ventricular assist devices during the study period: 69 in 2000-2003 (era 1), 135 in 2004-2006 (era 2), and 271 in 2007-2010 (era 3). Median age at ventricular assist device implantation was 6.0 years (interquartile range, 0.5-13.8), and the proportion of children who were 1-12 years old increased from 29% in era 1 to 47% in era 3 (p = 0.002). The majority of patients had a diagnosis of cardiomyopathy; this increased from 52% in era 1 to 72% in era 3 (p = 0.003). Comorbidities included arrhythmias (48%), pulmonary hypertension (16%), acute renal failure (34%), cerebrovascular disease (28%), and sepsis/systemic inflammatory response syndrome (34%). Two hundred forty-seven patients (52%) underwent heart transplantation and 327 (69%) survived to hospital discharge. Hospital mortality decreased from 42% in era 1 to 25% in era 3 (p = 0.004). Median hospital length of stay increased (37 d [interquartile range, 12-64 d] in era 1 vs 69 d [interquartile range, 35-130] in era 3; p < 0.001) and median adjusted hospital charges increased ($630,630 [interquartile range, $227,052-$853,318] in era 1 vs $1,577,983 [interquartile range, $874,463-$2,280,435] in era 3; p < 0.001). Factors associated with increased mortality include age less than 1 year (odds ratio, 2.04; 95% CI, 1.01-3.83), acute renal failure (odds ratio, 2.1; 95

Ventricular assist device implantation in a young patient with non-compaction cardiomyopathy and hereditary spherocytosis.

PubMed

Huenges, Katharina; Panholzer, Bernd; Cremer, Jochen; Haneya, Assad

2018-04-01

A case of a 15-year-old female patient with acute heart failure due to non-compaction cardiomyopathy and hereditary anaemia (hereditary spherocytic elliptocytosis) requiring ventricular assist device implantation as a bridge to transplantation is presented. The possible effects of mechanical stress on erythrocytes potentially induced by mechanical circulatory support remains unclear, but it may lead to haemolytic crisis in patients suffering from hereditary anaemia. In our case, ventricular assist device therapy was feasible, and haematological complications did not occur within 6 weeks of bridging our patient to heart transplantation.

Perioperative management of calves undergoing implantation of a left ventricular assist device.

PubMed

Wilson, D V; Kantrowitz, A; Pacholewicz, J; Salat, O; Paules, B R; Zhou, Y; Dawe, E J

2000-01-01

To describe perioperative management of calves that underwent left lateral thoracotomy, aortic cross-clamping, partial left heart bypass and implantation of a left ventricular assist device. A total of 43 healthy castrated male calves, weighing 121 +/- 24 kg. Diazepam (mean +/- SD, 0.26 +/- 0.07 mg/kg), ketamine (5.9 +/- 2.17 mg/kg) and isoflurane were used in the anesthetic management of calves undergoing implantation of a left ventricular assist device in the descending thoracic aorta. Other adjunctive agents administered were fentanyl (11 +/- 5.4 microg/kg), lidocaine (4.9 +/- 3.19 mg/kg), bupivacaine (0.75%) and butorphanol (0.49 +/- 0.13 mg/kg). None of the calves regurgitated at induction or during intubation. A tube was used to drain the rumen and prevent bloat during the procedure. Partial left heart bypass was used to perfuse the caudal half of the body during the period of aortic cross clamp and device implantation. Initial mean systemic blood pressure was 96 +/- 25 mm Hg, and pressures measured in the auricular artery increased during aortic cross-clamping and bypass. Vasoconstrictor therapy was required to treat caudal arterial hypotension during the procedure in 9 calves. Mean systemic arterial pressures returned to baseline values by the end of the anesthetic period. Initial mean pulmonary arterial pressures (PAP) were 22 +/- 3 mm Hg. A significant but transient increase in pulmonary arterial pressure occurred after both heparin and protamine administration. The described anesthetic protocol was effective for thoracotomy and implantation of an intra-aortic left ventricular assist device in normal calves. Partial left ventricular bypass was a useful adjunct during the period of aortic cross clamp. The doses of heparin and protamine administered were effective. Responsibility to monitor oxygenation of the cranial half of the animal continues during the bypass period as hypoxemia due to pulmonary dysfunction will not be detected by the perfusionist.

Surgical treatment of tricuspid valve insufficiency promotes early reverse remodeling in patients with axial-flow left ventricular assist devices.

PubMed

Maltais, Simon; Topilsky, Yan; Tchantchaleishvili, Vakhtang; McKellar, Stephen H; Durham, Lucian A; Joyce, Lyle D; Daly, Richard C; Park, Soon J

2012-06-01

The HeartMate II (Thoratec Corp, Pleasanton, Calif) continuous-flow left ventricular assist device has emerged as the standard of care for patients with advanced heart failure. The objective of this study was to assess the safety and early effectiveness of concomitant tricuspid valve procedures in patients undergoing implantation of a HeartMate II device. From February 2007 to April 2010, 83 patients underwent HeartMate II left ventricular assist device implantation. Of these, 37 patients had concomitant tricuspid valve procedures (32 repairs, 5 replacements) for severe tricuspid regurgitation. The effects of a tricuspid valve procedure on tricuspid regurgitation and right ventricular remodeling were assessed comparing echocardiographic findings at baseline and 30 days after left ventricular assist device implantation. Overall survival was also compared. Patients undergoing a concomitant tricuspid valve procedure had more tricuspid regurgitation (vena contracta, 5.6 ± 2.1 mm vs 2.9 ± 2.0 mm; P < .001), worse right ventricular dysfunction (right ventricular end-diastolic area, 33.6 ± 6.2 mm vs 31.6 ± 8.5 mm; P = .05), higher mean right atrial pressure (17.4 ± 7.1 mm Hg vs 14.9 ± 5.1 mm Hg; P = .03), and a higher Kormos score (2.6 ± 2.1 vs 1.2 ± 1.4; P = .0008) preoperatively. One month after surgery, tricuspid regurgitation was worse in patients who underwent left ventricular assist device implantation alone (+18.6%), whereas it improved significantly in patients undergoing a concomitant tricuspid valve procedure (-50.2%) (P = .005). A corresponding significant reduction in right ventricular end-diastolic area (33.6% ± 6.2% vs 30.1% ± 9.7%; P = .03) and a trend toward better right ventricular function (55.5% ± 79.7% vs 35.7% ± 60.5%; P = .28) were noted in patients undergoing a concomitant tricuspid valve procedure. Survival was comparable between the 2 groups. In patients with severe tricuspid regurgitation undergoing left ventricular assist device

In vivo quantification of intraventricular flow during left ventricular assist device support

NASA Astrophysics Data System (ADS)

Vu, Vi; Wong, Kin; Del Alamo, Juan; Aguilo, Pablo M. L.; May-Newman, Karen; Department of Bioengineering, San Diego State University Collaboration; Department of Mechanical; Aerospace Engineering, University of California San Diego Collaboration; Mechanical Assist Device Program, Sharp Memorial Hospital Collaboration

2014-11-01

Left ventricular assist devices (LVADs) are mechanical pumps that are surgically connected to the left ventricle (LV) and aorta to increase aortic flow and end-organ perfusion. Clinical studies have demonstrated that LVADs improve patient health and quality of life and significantly reduce the mortality of cardiac failure. However, In the presence of left ventricular assisted devices (LVAD), abnormal flow patterns and stagnation regions are often linked to thrombosis. The aim of our study is to evaluate the flow patterns in the left ventricle of the LVAD-assisted heart, with a focus on alterations in vortex development and blood stasis. To this aim, we applied color Doppler echocardiography to measure 2D, time resolved velocity fields in patients before and after implantation of LVADs. In agreement with our previous in vitro studies (Wong et al., Journal of Biomechanics 47, 2014), LVAD implantation resulted in decreased flow velocities and increased blood residence time near the outflow tract. The variation of residence time changes with LVAD operational speed was characterized for each patient.

Analysis of baroreflex sensitivity during undulation pump ventricular assist device support.

PubMed

Liu, Hongjian; Shiraishi, Yasuyuki; Zhang, Xiumin; Song, Hojin; Saijo, Yoshifumi; Baba, Atsushi; Yambe, Tomoyuki; Abe, Yusuke; Imachi, Kou

2009-07-01

The aim of this study was to examine the baroreflex sensitivity (BRS), which involves the autonomic nervous system, in a goat with a chronically implanted undulation pump ventricular assist device (UPVAD). The UPVAD involved transforming the rotation of a brushless DC motor into an undulating motion by a disc attached via a special linking mechanism, and a jellyfish valve in the outflow cannula to prevent diastolic backflow. The pump was implanted into the thoracic cavity of a goat by a left thoracotomy, and the inflow and outflow cannulae were sutured to the apex of the left ventricle and to the descending aorta, respectively. The driving cable was wired percutaneously to an external controller. Electrocardiogram and hemodynamic waveforms were recorded at a sampling frequency of 1 kHz. BRS was determined when awake by the slope of the linear regression of R-R interval against mean arterial pressure changes, which were induced by the administration of methoxamine hydrochloride, both with continuous driving of the UPVAD as well as without assistance. BRS values during the UPVAD support and without assistance were 1.60 +/- 0.30 msec/mm Hg and 0.98 +/- 0.22 msec/mm Hg (n = 5, P < 0.05), respectively. BRS was significantly improved during left ventricular assistance. Therefore, UPVAD support might decrease sympathetic nerve activity and increase parasympathetic nerve activity to improve both microcirculation and organ function.

Outcomes of HeartWare Ventricular Assist System support in 141 patients: a single-centre experience.

PubMed

Wu, Long; Weng, Yu-Guo; Dong, Nian-Guo; Krabatsch, Thomas; Stepanenko, Alexander; Hennig, Ewald; Hetzer, Roland

2013-07-01

A third-generation ventricular assist device, the HeartWare Ventricular Assist System, has demonstrated its reliability and durability in animal models and clinical experience. However, studies of a large series of applications are still lacking. We evaluate the safety and efficacy of the HeartWare pump in 141 patients with end-stage heart failure at a single centre. A total of 141 patients (116 men and 25 women with a mean age of 52 years) in New York Heart Association (NYHA) Class IV received implantation of the HeartWare Ventricular Assist System between August 2009 and April 2011 at the Deutsches Herzzentrum Berlin. The outcomes were measured in terms of laboratory data, adverse events, NYHA functional class and survival during device support. The HeartWare system provided an adequate haemodynamic support for patients both inside and outside the hospital. NYHA class improved to I-II. Organ function and pulmonary vascular resistance improved significantly. In this cohort of patients, 14 patients underwent heart transplantation, one had had the device explanted following myocardial recovery, one had changed to another assist device, 81 were on ongoing support and 44 died. The overall actuarial survival rates at 6 and 12 months were 70 and 67%, respectively, and the 3-, 6- and 12-month survival rates on a left ventricular assist device (LVAD) support for bridge to transplantation patients were 82, 81 and 79%, respectively. Infection and bleeding were the main adverse events. Four patients underwent an LVAD exchange for pump thrombosis. The HeartWare system provides a safe and effective circulatory support in a population with a wide range of body surface areas, with a satisfactory actuarial survival time and an improved quality of life. It can be used for univentricular or biventricular support, being implanted into the pericardial space with simplified surgical techniques.

Use of Ventricular Assist Device in Univentricular Physiology: The Role of Lumped Parameter Models.

PubMed

Di Molfetta, Arianna; Ferrari, Gianfranco; Filippelli, Sergio; Fresiello, Libera; Iacobelli, Roberta; Gagliardi, Maria G; Amodeo, Antonio

2016-05-01

Failing single-ventricle (SV) patients might benefit from ventricular assist devices (VADs) as a bridge to heart transplantation. Considering the complex physiopathology of SV patients and the lack of established experience, the aim of this work was to realize and test a lumped parameter model of the cardiovascular system, able to simulate SV hemodynamics and VAD implantation effects. Data of 30 SV patients (10 Norwood, 10 Glenn, and 10 Fontan) were retrospectively collected and used to simulate patients' baseline. Then, the effects of VAD implantation were simulated. Additionally, both the effects of ventricular assistance and cavopulmonary assistance were simulated in different pathologic conditions on Fontan patients, including systolic dysfunction, diastolic dysfunction, and pulmonary vascular resistance increment. The model can reproduce patients' baseline well. Simulation results suggest that the implantation of VAD: (i) increases the cardiac output (CO) in all the three palliation conditions (Norwood 77.2%, Glenn 38.6%, and Fontan 17.2%); (ii) decreases the SV external work (SVEW) (Norwood 55%, Glenn 35.6%, and Fontan 41%); (iii) increases the mean pulmonary arterial pressure (Pap) (Norwood 39.7%, Glenn 12.1%, and Fontan 3%). In Fontan circulation, with systolic dysfunction, the left VAD (LVAD) increases CO (35%), while the right VAD (RVAD) determines a decrement of inferior vena cava pressure (Pvci) (39%) with 34% increment of CO. With diastolic dysfunction, the LVAD increases CO (42%) and the RVAD decreases the Pvci. With pulmonary vascular resistance increment, the RVAD allows the highest CO (50%) increment with the highest decrement of Pvci (53%). The single ventricular external work (SVEW) increases (decreases) increasing the VAD speed in cavopulmonary (ventricular) assistance. Numeric models could be helpful in this challenging and innovative field to support patients and VAD selection to optimize the clinical outcome and personalize the therapy

Left ventricular assist device malfunction: a systematic approach to diagnosis.

PubMed

Horton, Steven C; Khodaverdian, Reza; Powers, Amanda; Revenaugh, James; Renlund, Dale G; Moore, Stephanie A; Rasmusson, Brad; Nelson, Karl E; Long, James W

2004-05-05

A protocol was designed to diagnose the common malfunctions of a left ventricular assist device (LVAD). Mechanical circulatory support, primarily with an LVAD, is increasingly used for treatment of advanced heart failure (HF). Left ventricular assist device dysfunction is a recognized complication; but heretofore, a systematic method to accurately diagnose LVAD dysfunction has not been thoroughly described. We developed a catheter-based protocol designed to characterize a normally functioning LVAD and diagnose multiple types of dysfunction. A total of 15 studies of 10 patients supported with an LVAD were reviewed. All patients had been evaluated due to concerns regarding LVAD dysfunction. Of 15 examinations performed, 11 documented severe LVAD inflow valve regurgitation. One of these cases proved to have coexistent severe mitral valve regurgitation. One case was diagnosed with distortion of the LVAD outflow graft. One case of suspected embolization from the pumping chamber excluded the outflow graft as the source of emboli. One study had aortic insufficiency. As LVAD use for treatment of end-stage HF becomes widespread and durations of support are extended, dysfunction will be increasingly prevalent. This catheter-based protocol provided a practical method to diagnose multiple causes of LVAD dysfunction.

The effect of heart failure and left ventricular assist device treatment on right ventricular mechanics: a computational study.

PubMed

Park, Jun I K; Heikhmakhtiar, Aulia Khamas; Kim, Chang Hyun; Kim, Yoo Seok; Choi, Seong Wook; Song, Kwang Soup; Lim, Ki Moo

2018-05-22

Although it is important to analyze the hemodynamic factors related to the right ventricle (RV) after left ventricular assist device (LVAD) implantation, previous studies have focused only on the alteration of the ventricular shape and lack quantitative analysis of the various hemodynamic parameters. Therefore, we quantitatively analyzed various hemodynamic parameters related to the RV under normal, heart failure (HF), and HF incorporated with continuous flow LVAD therapy by using a computational model. In this study, we combined a three-dimensional finite element electromechanical model of ventricles, which is based on human ventricular morphology captured by magnetic resonance imaging (MRI) with a lumped model of the circulatory system and continuous flow LVAD function in order to construct an integrated model of an LVAD implanted-cardiovascular system. To induce systolic dysfunction, the magnitude of the calcium transient function under HF condition was reduced to 70% of the normal value, and the time constant was reduced by 30% of the normal value. Under the HF condition, the left ventricular end systolic pressure decreased, the left ventricular end diastolic pressure increased, and the pressure in the right atrium (RA), RV, and pulmonary artery (PA) increased compared with the normal condition. The LVAD therapy decreased the end-systolic pressure of the LV by 41%, RA by 29%, RV by 53%, and PA by 71%, but increased the right ventricular ejection fraction by 52% and cardiac output by 40%, while the stroke work was reduced by 67% compared with the HF condition without LVAD. The end-systolic ventricular tension and strain decreased with the LVAD treatment. LVAD enhances CO and mechanical unloading of the LV as well as those of the RV and prevents pulmonary hypertension which can be induced by HF.

In vitro characterization of a magnetically suspended continuous flow ventricular assist device.

PubMed

Kim, H C; Bearnson, G B; Khanwilkar, P S; Olsen, D B; Maslen, E H; Allaire, P E

1995-01-01

A magnetically suspended continuous flow ventricular assist device using magnetic bearings was developed aiming at an implantable ventricular assist device. The main advantage of this device includes no mechanical wear and minimal chance of blood trauma such, as thrombosis and hemolysis, because there is no mechanical contact between the stationary and rotating parts. The total system consists of two subsystems: the centrifugal pump and the magnetic bearing. The centrifugal pump is comprised of a 4 vane logarithmic spiral radial flow impeller and a brushless DC motor with slotless stator, driven by the back emf commutation scheme. Two radial and one thrust magnetic bearing that dynamically controls the position of the rotor in a radial and axial direction, respectively, contains magnetic coils, the rotor's position sensors, and feedback electronic control system. The magnetic bearing system was able to successfully suspend a 365.5g rotating part in space and sustain it for up to 5000 rpm of rotation. Average force-current square factor of the magnetic bearing was measured as 0.48 and 0.44 (kg-f/Amp2) for radial and thrust bearing, respectively. The integrated system demonstrated adequate performance in mock circulation tests by providing a 6 L/min flow rate against 100 mmHg differential pressure at 2300 rpm. Based on these in vitro performance test results, long-term clinical application of the magnetically suspended continuous flow ventricular assist device is very promising after system optimization with a hybrid system using both active (electromagnet) and passive (permanent magnets) magnet bearings.

Early Right Ventricular Assist Device Use in Patients Undergoing Continuous-Flow Left Ventricular Assist Device Implantation: Incidence and Risk Factors From the Interagency Registry for Mechanically Assisted Circulatory Support.

PubMed

Kiernan, Michael S; Grandin, E Wilson; Brinkley, Marshall; Kapur, Navin K; Pham, Duc Thinh; Ruthazer, Robin; Rame, J Eduardo; Atluri, Pavan; Birati, Edo Y; Oliveira, Guilherme H; Pagani, Francis D; Kirklin, James K; Naftel, David; Kormos, Robert L; Teuteberg, Jeffrey J; DeNofrio, David

2017-10-01

To investigate preimplant risk factors associated with early right ventricular assist device (RVAD) use in patients undergoing continuous-flow left ventricular assist device (LVAD) surgery. Patients in the Interagency Registry for Mechanically Assisted Circulatory Support who underwent primary continuous-flow-LVAD surgery were examined for concurrent or subsequent RVAD implantation within 14 days of LVAD. Risk factors for RVAD implantation and the combined end point of RVAD or death within 14 days of LVAD were assessed with stepwise logistic regression. We compared survival between patients with and without RVAD using Kaplan-Meier method and Cox proportional hazards modeling. Of 9976 patients undergoing continuous-flow-LVAD implantation, 386 patients (3.9%) required an RVAD within 14 days of LVAD surgery. Preimplant characteristics associated with RVAD use included interagency registry for mechanically assisted circulatory support patient profiles 1 and 2, the need for preoperative extracorporeal membrane oxygenation or renal replacement therapy, severe preimplant tricuspid regurgitation, history of cardiac surgery, and concomitant procedures other than tricuspid valve repair at the time of LVAD. Hemodynamic determinants included elevated right atrial pressure, reduced pulmonary artery pulse pressure, and reduced stroke volume. The final model demonstrated good performance for both RVAD implant (area under the curve, 0.78) and the combined end point of RVAD or death within 14 days (area under the curve, 0.73). Compared with patients receiving an isolated LVAD, patients requiring RVAD had decreased 1- and 6-month survival: 78.1% versus 95.8% and 63.6% versus 87.9%, respectively ( P <0.0001 for both). The need for RVAD implantation after LVAD is associated with indices of global illness severity, markers of end-organ dysfunction, and profiles of hemodynamic instability. © 2017 American Heart Association, Inc.

De novo development of eosinophilic myocarditis with left ventricular assist device support as bridge to transplant.

PubMed

Pereira, Naveen L; Park, Soon J; Daly, Richard C; Kushwaha, Sudhir S; Edwards, William D

2010-10-01

The de novo development of myocarditis during left ventricular assist device support for dilated cardiomyopathy has not been previously described. We report a case of severe eosinophilic myocarditis associated with the use of leukotriene-receptor antagonist montelukast that developed during left ventricular assist device support accompanied by intra-device thrombus formation that was hemodynamically tolerated and subsequently discovered in the explanted heart. There may be no visible change in cardiac function as assessed by echocardiography, but the diagnosis should be entertained with the development of peripheral eosinophilia. Copyright © 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Technological Innovations from NASA

NASA Technical Reports Server (NTRS)

Pellis, Neal R.

2006-01-01

The challenge of human space exploration places demands on technology that push concepts and development to the leading edge. In biotechnology and biomedical equipment development, NASA science has been the seed for numerous innovations, many of which are in the commercial arena. The biotechnology effort has led to rational drug design, analytical equipment, and cell culture and tissue engineering strategies. Biomedical research and development has resulted in medical devices that enable diagnosis and treatment advances. NASA Biomedical developments are exemplified in the new laser light scattering analysis for cataracts, the axial flow left ventricular-assist device, non contact electrocardiography, and the guidance system for LASIK surgery. Many more developments are in progress. NASA will continue to advance technologies, incorporating new approaches from basic and applied research, nanotechnology, computational modeling, and database analyses.

The successful implantation of continuous-flow left ventricular assist device as a destination therapy in Korea: echocardiographic assessment.

PubMed

Lee, Ga Yeon; Park, Sung-Ji; Kim, Sujin; Choi, Namgyung; Jeong, Dong Seop; Jeon, Eun-Seok; Lee, Young Tak

2014-01-01

Left ventricular assist device (LVAD) is a good treatment option for the patients ineligible for cardiac transplantation. Several studies have demonstrated that a ventricular assist device improves the quality of life and prognosis of the patients with end-stage heart failure. A 75-yr-old man debilitated with New York Heart Association (NYHA) functional class III-IV due to severe left ventricular systolic dysfunction received LVAD implantation as a destination therapy. The patient was discharged with improved functional status (NYHA functional class II) after appropriate cardiac rehabilitation and education about how to manage the device and potential emergency situations. This is the first case of successful continuous-flow LVAD implantation as a destination therapy in Korea.

Intraoperative bronchoscopic visualization of left ventricular assist device thrombus.

PubMed

Yost, Gardner; Bhat, Geetha; Modi, Sejal; Pappas, Pat; Tatooles, Antone

2016-07-01

Despite advancements in left ventricular assist device (LVAD) design and clinical management, device thrombosis remains a pertinent complication. Limited imaging makes precise visualization of clot location and shape very challenging. We report the usage of videobronchoscopic exploration of explanted LVADs for direct visualization of clot in two patients. This technique is a rapid and inexpensive means of improving our understanding of LVAD clot formation and may be useful in surgical exploration of inflow and outflow tracts during LVAD exchange. © The Author(s) 2015.

Heart monitoring using left ventricle impedance and ventricular electrocardiography in left ventricular assist device patients.

PubMed

Her, Keun; Ahn, Chi Bum; Park, Sung Min; Choi, Seong Wook

2015-03-21

Patients who develop critical arrhythmia during left ventricular assist device (LVAD) perfusion have a low survival rate. For diagnosis of unexpected heart abnormalities, new heart-monitoring methods are required for patients supported by LVAD perfusion. Ventricular electrocardiography using electrodes implanted in the ventricle to detect heart contractions is unsuitable if the heart is abnormal. Left ventricular impedance (LVI) is useful for monitoring heart movement but does not show abnormal action potential in the heart muscle. To detect detailed abnormal heart conditions, we obtained ventricular electrocardiograms (v-ECGs) and LVI simultaneously in porcine models connected to LVADs. In the porcine models, electrodes were set on the heart apex and ascending aorta for real-time measurements of v-ECGs and LVI. As the carrier current frequency of the LVI was adjusted to 30 kHz, it was easily derived from the original v-ECG signal by using a high-pass filter (cutoff: 10 kHz). In addition, v-ECGs with a frequency band of 0.1 - 120 Hz were easily derived using a low-pass filter. Simultaneous v-ECG and LVI data were compared to detect heart volume changes during the Q-T period when the heart contracted. A new real-time algorithm for comparison of v-ECGs and LVI determined whether the porcine heartbeats were normal or abnormal. Several abnormal heartbeats were detected using the LVADs operating in asynchronous mode, most of which were premature ventricle contractions (PVCs). To evaluate the accuracy of the new method, the results obtained were compared to normal ECG data and cardiac output measured simultaneously using commercial devices. The new method provided more accurate detection of abnormal heart movements. This method can be used for various heart diseases, even those in which the cardiac output is heavily affected by LVAD operation.

Verification of a computational cardiovascular system model comparing the hemodynamics of a continuous flow to a synchronous valveless pulsatile flow left ventricular assist device.

PubMed

Gohean, Jeffrey R; George, Mitchell J; Pate, Thomas D; Kurusz, Mark; Longoria, Raul G; Smalling, Richard W

2013-01-01

The purpose of this investigation is to use a computational model to compare a synchronized valveless pulsatile left ventricular assist device with continuous flow left ventricular assist devices at the same level of device flow, and to verify the model with in vivo porcine data. A dynamic system model of the human cardiovascular system was developed to simulate the support of a healthy or failing native heart from a continuous flow left ventricular assist device or a synchronous pulsatile valveless dual-piston positive displacement pump. These results were compared with measurements made during in vivo porcine experiments. Results from the simulation model and from the in vivo counterpart show that the pulsatile pump provides higher cardiac output, left ventricular unloading, cardiac pulsatility, and aortic valve flow as compared with the continuous flow model at the same level of support. The dynamic system model developed for this investigation can effectively simulate human cardiovascular support by a synchronous pulsatile or continuous flow ventricular assist device.

Verification of a computational cardiovascular system model comparing the hemodynamics of a continuous flow to a synchronous valveless pulsatile flow left ventricular assist device

PubMed Central

Gohean, Jeffrey R.; George, Mitchell J.; Pate, Thomas D.; Kurusz, Mark; Longoria, Raul G.; Smalling, Richard W.

2012-01-01

The purpose of this investigation is to utilize a computational model to compare a synchronized valveless pulsatile left ventricular assist device to continuous flow left ventricular assist devices at the same level of device flow, and to verify the model with in vivo porcine data. A dynamic system model of the human cardiovascular system was developed to simulate support of a healthy or failing native heart from a continuous flow left ventricular assist device or a synchronous, pulsatile, valveless, dual piston positive displacement pump. These results were compared to measurements made during in vivo porcine experiments. Results from the simulation model and from the in vivo counterpart show that the pulsatile pump provides higher cardiac output, left ventricular unloading, cardiac pulsatility, and aortic valve flow as compared to the continuous flow model at the same level of support. The dynamic system model developed for this investigation can effectively simulate human cardiovascular support by a synchronous pulsatile or continuous flow ventricular assist device. PMID:23438771

Management of pump thrombosis in patients with left ventricular assist devices.

PubMed

Stulak, John M; Sharma, Shashank; Maltais, Simon

2015-04-01

The gradual evolution of left ventricular assist device (LVAD) therapy has resulted in a durable option for patients as either a bridge to transplantation (BTT) or a destination therapy (DT). Outcomes with current continuous-flow devices continue to demonstrate significant patient benefit, not only in enhanced survival but also in improved functional capacity and quality of life. While the lessening of adverse events through time has resulted in more widespread adoption of this therapy, there continues to be unintended consequences, including, most notably, infection, bleeding, and thrombosis. Beginning in 2011, centers and collaborative groups began to observe a significant increase in the incidence of pump thrombosis with the HeartMate II LVAD (Thoratec Corp., Pleasanton, CA, USA). However, this clinical scourge is not limited to the HeartMate II, as the HeartWare Ventricular Assist System (HVAD; HeartWare Inc., Framingham, MA, USA) has also had these same issues, which led to pump modifications and the appreciation of more strict control of blood pressure and anticoagulation with this pump design. We review the current status of the field of mechanical circulatory support in its approach to diagnosis, management, and prevention of LVAD pump thrombosis.

Left ventricular diastolic filling with an implantable ventricular assist device: beat to beat variability with overall improvement

NASA Technical Reports Server (NTRS)

Nakatani, S.; Thomas, J. D.; Vandervoort, P. M.; Zhou, J.; Greenberg, N. L.; Savage, R. M.; McCarthy, P. M.

1997-01-01

OBJECTIVES: We studied the effects of left ventricular (LV) unloading by an implantable ventricular assist device on LV diastolic filling. BACKGROUND: Although many investigators have reported reliable systemic and peripheral circulatory support with implantable LV assist devices, little is known about their effect on cardiac performance. METHODS: Peak velocities of early diastolic filling, late diastolic filling, late to early filling ratio, deceleration time of early filling, diastolic filling period and atrial filling fraction were measured by intraoperative transesophageal Doppler echocardiography before and after insertion of an LV assist device in eight patients. A numerical model was developed to simulate this situation. RESULTS: Before device insertion, all patients showed either a restrictive or a monophasic transmitral flow pattern. After device insertion, transmitral flow showed rapid beat to beat variation in each patient, from abnormal relaxation to restrictive patterns. However, when the average values obtained from 10 consecutive beats were considered, overall filling was significantly normalized from baseline, with early filling velocity falling from 87 +/- 31 to 64 +/- 26 cm/s (p < 0.01) and late filling velocity rising from 8 +/- 11 to 32 +/- 23 cm/s (p < 0.05), resulting in an increase in the late to early filling ratio from 0.13 +/- 0.18 to 0.59 +/- 0.38 (p < 0.01) and a rise in the atrial filling fraction from 8 +/- 10% to 26 +/- 17% (p < 0.01). The deceleration time (from 112 +/- 40 to 160 +/- 44 ms, p < 0.05) and the filling period corrected by the RR interval (from 39 +/- 8% to 54 +/- 10%, p < 0.005) were also significantly prolonged. In the computer model, asynchronous LV assistance produced significant beat to beat variation in filling indexes, but overall a normalization of deceleration time as well as other variables. CONCLUSIONS: With LV assistance, transmitral flow showed rapidly varying patterns beat by beat in each patient, but

Left ventricular assist device implantation via left thoracotomy: alternative to repeat sternotomy.

PubMed

Pierson, Richard N; Howser, Renee; Donaldson, Terri; Merrill, Walter H; Dignan, Rebecca J; Drinkwater, Davis C; Christian, Karla G; Butler, Javed; Chomsky, Don; Wilson, John R; Clark, Rick; Davis, Stacy F

2002-03-01

Repeat sternotomy for left ventricular assist device insertion may result in injury to the right heart or patent coronary grafts, complicating intraoperative and postoperative management. In 4 critically ill patients, left thoracotomy was used as an alternative to repeat sternotomy. Anastomosis of the outflow conduit to the descending thoracic aorta provided satisfactory hemodynamic support.

Hemodynamic Performance of a Novel Right Ventricular Assist Device (PERKAT).

PubMed

Kretzschmar, Daniel; Schulze, P Christian; Ferrari, Markus W

Acute right ventricular failure (RVF) is an increasing clinical problem and a life-threatening condition. Right ventricular assist devices represent a reasonable treatment option for patients with refractory RVF. We here present a novel percutaneously implantable device for right ventricular support. The PERKAT device is based on a nitinol stent cage, which is covered with valve-carrying foils. A flexible outlet trunk with a pigtail tip is connected to the distal part. The device is driven by an intra-aortic balloon pump (IABP) drive unit, which inflates/deflates a standard IABP-balloon placed within the stent cage. In-vitro evaluation was done in a liquid bath containing water or blood analog. The PERKAT device was tested in different afterload settings using two different IABP-balloons and varying inflation/deflation rates. We detected flow rates ranging from 1.97 to 3.93 L/min depending on the afterload setting, inflation/deflation rate, balloon size, and the medium used. Flow rates between water and blood analog were nearly comparable, and in the higher inflation/deflation rate settings slightly higher with water. Based on this promising in vitro data, the innovative percutaneously implantable PERKAT device has a potential to become a therapeutic option for patients with RVF refractory to medical treatment.

Transesophageal Echocardiography-Guided Epicardial Left Ventricular Lead Placement by Video-Assisted Thoracoscopic Surgery in Nonresponders to Biventricular Pacing and Previous Chest Surgery.

PubMed

Schroeder, Carsten; Chung, Jane M; Mackall, Judith A; Cakulev, Ivan T; Patel, Aaron; Patel, Sunny J; Hoit, Brian D; Sahadevan, Jayakumar

2018-06-14

The aim of the study was to study the feasibility, safety, and efficacy of transesophageal echocardiography-guided intraoperative left ventricular lead placement via a video-assisted thoracoscopic surgery approach in patients with failed conventional biventricular pacing. Twelve patients who could not have the left ventricular lead placed conventionally underwent epicardial left ventricular lead placement by video-assisted thoracoscopic surgery. Eight patients had previous chest surgery (66%). Operative positioning was a modified far lateral supine exposure with 30-degree bed tilt, allowing for groin and sternal access. To determine the optimal left ventricular location for lead placement, the left ventricular surface was divided arbitrarily into nine segments. These segments were transpericardially paced using a hand-held malleable pacing probe identifying the optimal site verified by transesophageal echocardiography. The pacing leads were screwed into position via a limited pericardiotomy. The video-assisted thoracoscopic surgery approach was successful in all patients. Biventricular pacing was achieved in all patients and all reported symptomatic benefit with reduction in New York Heart Association class from III to I-II (P = 0.016). Baseline ejection fraction was 23 ± 3%; within 1-year follow-up, the ejection fraction increased to 32 ± 10% (P = 0.05). The mean follow-up was 566 days. The median length of hospital stay was 7 days with chest tube removal between postoperative days 2 and 5. In patients who are nonresponders to conventional biventricular pacing, intraoperative left ventricular lead placement using anatomical and functional characteristics via a video-assisted thoracoscopic surgery approach is effective in improving heart failure symptoms. This optimized left ventricular lead placement is feasible and safe. Previous chest surgery is no longer an exclusion criterion for a video-assisted thoracoscopic surgery approach.

Percutaneous Ventricular Assist Devices: A Health Technology Assessment.

PubMed

2017-01-01

Percutaneous coronary intervention (PCI)-using a catheter to place a stent to keep blood vessels open-is increasingly used for high-risk patients who cannot undergo surgery. Cardiogenic shock (when the heart suddenly cannot pump enough blood) is associated with a high mortality rate. The percutaneous ventricular assist device can help control blood pressure and increase blood flow in these high-risk conditions. This health technology assessment examined the benefits, harms, and budget impact of the Impella percutaneous ventricular assist device in high-risk PCI and cardiogenic shock. We also analyzed cost-effectiveness of the Impella device in high-risk PCI. We performed a systematic search of the literature for studies examining the effects of the Impella percutaneous ventricular assist device in high-risk PCI and cardiogenic shock, and appraised the evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria, focusing on hemodynamic stability, mortality, major adverse cardiac events, bleeding, and vascular complications. We developed a Markov decision-analytical model to assess the cost- effectiveness of Impella devices versus intra-aortic balloon pumps (IABPs), calculated incremental cost-effectiveness ratios (ICERs) using a 10-year time horizon, and conducted sensitivity analyses to examine the robustness of the estimates. The economic model was conducted from the perspective of the Ontario Ministry of Health and Long-Term Care. Eighteen studies (one randomized controlled trial and 10 observational studies for high-risk PCI, and one randomized controlled trial and six observational studies for cardiogenic shock) were included in the clinical review. Compared with IABPs, Impella 2.5, one model of the device, improved hemodynamic parameters (GRADE low-very low) but showed no significant difference in mortality (GRADE low), major adverse cardiac events (GRADE low), bleeding (GRADE low), or vascular

Percutaneous Ventricular Assist Devices: A Health Technology Assessment

PubMed Central

Lee, Christine; Djalalov, Sandjar; Xie, Xuanqian; Holubowich, Corinne

2017-01-01

Background Percutaneous coronary intervention (PCI)—using a catheter to place a stent to keep blood vessels open—is increasingly used for high-risk patients who cannot undergo surgery. Cardiogenic shock (when the heart suddenly cannot pump enough blood) is associated with a high mortality rate. The percutaneous ventricular assist device can help control blood pressure and increase blood flow in these high-risk conditions. This health technology assessment examined the benefits, harms, and budget impact of the Impella percutaneous ventricular assist device in high-risk PCI and cardiogenic shock. We also analyzed cost-effectiveness of the Impella device in high-risk PCI. Methods We performed a systematic search of the literature for studies examining the effects of the Impella percutaneous ventricular assist device in high-risk PCI and cardiogenic shock, and appraised the evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria, focusing on hemodynamic stability, mortality, major adverse cardiac events, bleeding, and vascular complications. We developed a Markov decision-analytical model to assess the cost- effectiveness of Impella devices versus intra-aortic balloon pumps (IABPs), calculated incremental cost-effectiveness ratios (ICERs) using a 10-year time horizon, and conducted sensitivity analyses to examine the robustness of the estimates. The economic model was conducted from the perspective of the Ontario Ministry of Health and Long-Term Care. Results Eighteen studies (one randomized controlled trial and 10 observational studies for high-risk PCI, and one randomized controlled trial and six observational studies for cardiogenic shock) were included in the clinical review. Compared with IABPs, Impella 2.5, one model of the device, improved hemodynamic parameters (GRADE low–very low) but showed no significant difference in mortality (GRADE low), major adverse cardiac events (GRADE low

Multicenter Evaluation of Octreotide as Secondary Prophylaxis in Patients With Left Ventricular Assist Devices and Gastrointestinal Bleeding.

PubMed

Shah, Keyur B; Gunda, Sampath; Emani, Sitaramesh; Kanwar, Manreet K; Uriel, Nir; Colombo, Paolo C; Uber, Patricia A; Sears, Melissa L; Chuang, Joyce; Farrar, David J; Brophy, Donald F; Smallfield, George B

2017-11-01

Gastrointestinal (GI) bleeding is one of the most common complications after continuous-flow left ventricular assist device implantation. More than one third of patients with incident bleed go on to develop recurrent GI bleeding. Octreotide, a somatostatin analog, is proposed to reduce the risk of recurrent GI bleeding in this population. This multicenter, retrospective analysis evaluated 51 continuous-flow left ventricular assist device patients who received secondary prophylaxis with octreotide after their index GI bleed from 2009 to 2015. All patients had a hospitalization for GI bleed and received octreotide after discharge. Patient demographics, medical and medication history, and clinical characteristics of patients who rebled after receiving octreotide were compared with non-rebleeders. These data were also compared with matched historical control patients previously enrolled in the HMII (HeartMate II) clinical trials, none of whom received octreotide, to provide a context for the bleeding rates. Twelve patients (24%) who received secondary octreotide prophylaxis developed another GI bleed, whereas 39 (76%) did not. There were similar intergroup demographics; however, significantly more bleeders had a previous GI bleeding history before left ventricular assist device placement (33% versus 5%; P =0.02) and greater frequency of angiodysplasia confirmed during endoscopy (58% versus 23%; P =0.03). Fewer patients in this study experienced a recurrent GI bleed compared with a matched historical control group that did not receive octreotide (24% versus 43%; P =0.04). Patients with continuous-flow left ventricular assist device receiving secondary prophylaxis with octreotide had a significantly lower GI bleed recurrence compared with historical controls not treated with octreotide. Additional prospective studies are needed to confirm these data. © 2017 American Heart Association, Inc.

Endocarditis in left ventricular assist device

PubMed Central

Thyagarajan, Braghadheeswar; Kumar, Monisha Priyadarshini; Sikachi, Rutuja R; Agrawal, Abhinav

2016-01-01

Summary Heart failure is one of the leading causes of death in developed nations. End stage heart failure often requires cardiac transplantation for survival. The left ventricular assist device (LVAD) has been one of the biggest evolvements in heart failure management often serving as bridge to transplant or destination therapy in advanced heart failure. Like any other medical device, LVAD is associated with complications with infections being reported in many patients. Endocarditis developing secondary to the placement of LVAD is not a frequent, serious and difficult to treat condition with high morbidity and mortality. Currently, there are few retrospective studies and case reports reporting the same. In our review, we found the most common cause of endocarditis in LVAD was due to bacteria. Both bacterial and fungal endocarditis were associated with high morbidity and mortality. In this review we will be discussing the risk factors, organisms involved, diagnostic tests, management strategies, complications, and outcomes in patients who developed endocarditis secondary to LVAD placement. PMID:27672540

Cryoablation during left ventricular assist device implantation reduces postoperative ventricular tachyarrhythmias.

PubMed

Mulloy, Daniel P; Bhamidipati, Castigliano M; Stone, Matthew L; Ailawadi, Gorav; Bergin, James D; Mahapatra, Srijoy; Kern, John A

2013-05-01

The number of patients undergoing implantation of a HeartMate II left ventricular assist device (LVAD; Thoratec Corporation, Pleasanton, Calif) is rising. Ventricular tachyarrhythmia (VA) after placement of the device is common, especially among patients with preoperative VA. We sought to determine whether intraoperative cryoablation in select patients reduces the incidence of postoperative VA. From January 2009 through September 2010, 50 consecutive patients undergoing implantation of the HeartMate II LVAD were examined. Fourteen of these patients had recurrent preoperative VA. Of those patients with recurrent VA, half underwent intraoperative cryoablation (Cryo: n = 7) and half did not (NoCryo: n = 7). Intraoperatively, patients underwent localized epicardial and endocardial cryoablation via LVAD ventriculotomy. Cryothermal lesions were created to connect scar to fixed anatomic borders in the region of clinical VA. Demographics, risk factors, intraoperative features, and outcomes were analyzed to investigate the feasibility of cryoablation. Thirty-day mortality remained low (n = 1, 2%) among all LVAD recipients. There were no differences in risk factors between groups except that preoperative inotropes were less prevalent in Cryo patients (P = .09). Compared with NoCryo, the Cryo group had significantly decreased postoperative resource use and complications (P < .05). Recurrent postoperative VA did not develop in any of the Cryo patients (P = .02). Postoperative VA can be minimized by preoperative risk assessment and intraoperative treatment. Localized cryoablation in select patients offers promising early feasibility when performed during HeartMate II LVAD implantation. Further prospective analysis is required to investigate this novel approach. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Coronary bypass flow during use of intraaortic balloon pumping and left ventricular assist device.

PubMed

Tedoriya, T; Kawasuji, M; Sakakibara, N; Takemura, H; Watanabe, Y; Hetzer, R

1998-08-01

Intraaortic balloon pumping (IABP) and left ventricular assist device (LVAD) are used for left ventricular support when low cardiac output occurs after a coronary bypass operation for serious coronary artery disease. There are hemodynamic differences in blood flow in various kinds of coronary artery bypass grafts, caused by their inherent physiologic characteristics. The hemodynamic effects of left ventricular assistance with IABP and LVAD on blood flow through various coronary artery bypass grafts were investigated. An ascending aorta-coronary bypass graft (ACB), an internal thoracic artery, and a descending aorta-coronary bypass graft were anastomosed to the left anterior descending coronary artery in a canine model. In this experimental model, the blood flow to the same coronary bed in the three types of grafts could be evaluated. Blood flow in the left anterior descending coronary artery through the three types of coronary bypass grafts was studied in this model during or in the absence of ventricular assistance. In the control study, the systolic blood flow did not differ among the three types of grafts, but the diastolic flow decreased in the following order: with the ACB, the internal thoracic artery, and the descending aorta-coronary bypass graft. The systolic flow during IABP and LVAD was similar to the control flows. Use of IABP increased the diastolic flow by 75.3%+/-12.4% of the control value in the ACB, 37.9%+/-25.0% in the internal thoracic artery, and 21.2%+/-11.4% in the descending aorta-coronary bypass graft. The LVAD increased the diastolic flow by 97.7%+/-18.7% of the control value in the ACB, 64.5%+/-25.7% in the internal thoracic artery, and 63.0%+/-27.9% in the descending aorta-coronary bypass graft. The diastolic blood flows in the left anterior descending coronary artery and the three types of grafts were significantly greater with IABP than the control values, and significantly greater with LVAD than with IABP and the control values. The

To ventricular assist devices or not: When is implantation of a ventricular assist device appropriate in advanced ambulatory heart failure?

PubMed Central

Cerier, Emily; Lampert, Brent C; Kilic, Arman; McDavid, Asia; Deo, Salil V; Kilic, Ahmet

2016-01-01

Advanced heart failure has been traditionally treated via either heart transplantation, continuous inotropes, consideration for hospice and more recently via left ventricular assist devices (LVAD). Heart transplantation has been limited by organ availability and the futility of other options has thrust LVAD therapy into the mainstream of therapy for end stage heart failure. Improvements in technology and survival combined with improvements in the quality of life have made LVADs a viable option for many patients suffering from heart failure. The question of when to implant these devices in those patients with advanced, yet still ambulatory heart failure remains a controversial topic. We discuss the current state of LVAD therapy and the risk vs benefit of these devices in the treatment of heart failure. PMID:28070237

Mechanical Circulatory Support of the Critically Ill Child Awaiting Heart Transplantation

PubMed Central

Gazit, Avihu Z; Gandhi, Sanjiv K; C Canter, Charles

2010-01-01

The majority of children awaiting heart transplantation require inotropic support, mechanical ventilation, and/or extracorporeal membrane oxygenation (ECMO) support. Unfortunately, due to the limited pool of organs, many of these children do not survive to transplant. Mechanical circulatory support of the failing heart in pediatrics is a new and rapidly developing field world-wide. It is utilized in children with acute congestive heart failure associated with congenital heart disease, cardiomyopathy, and myocarditis, both as a bridge to transplantation and as a bridge to myocardial recovery. The current arsenal of mechanical assist devices available for children is limited to ECMO, intra-aortic balloon counterpulsation, centrifugal pump ventricular assist devices, the DeBakey ventricular assist device Child; the Thoratec ventricular assist device; and the Berlin Heart. In the spring of 2004, five contracts were awarded by the National Heart, Lung and Blood Institute to support preclinical development for a range of pediatric ventricular assist devices and similar circulatory support systems. The support of early development efforts provided by this program is expected to yield several devices that will be ready for clinical trials within the next few years. Our work reviews the current international experience with mechanical circulatory support in children and summarizes our own experience since 2005 with the Berlin Heart, comparing the indications for use, length of support, and outcome between these modalities. PMID:21286278

Restoration of Pulsatile Flow Reduces Sympathetic Nerve Activity Among Individuals With Continuous-Flow Left Ventricular Assist Devices.

PubMed

Cornwell, William K; Tarumi, Takashi; Stickford, Abigail; Lawley, Justin; Roberts, Monique; Parker, Rosemary; Fitzsimmons, Catherine; Kibe, Julius; Ayers, Colby; Markham, David; Drazner, Mark H; Fu, Qi; Levine, Benjamin D

2015-12-15

Current-generation left ventricular assist devices provide circulatory support that is minimally or entirely nonpulsatile and are associated with marked increases in muscle sympathetic nerve activity (MSNA), likely through a baroreceptor-mediated pathway. We sought to determine whether the restoration of pulsatile flow through modulations in pump speed would reduce MSNA through the arterial baroreceptor reflex. Ten men and 3 women (54 ± 14 years) with Heartmate II continuous-flow left ventricular assist devices underwent hemodynamic and sympathetic neural assessment. Beat-to-beat blood pressure, carotid ultrasonography at the level of the arterial baroreceptors, and MSNA via microneurography were continuously recorded to determine steady-state responses to step changes (200-400 revolutions per minute) in continuous-flow left ventricular assist device pump speed from a maximum of 10,480 ± 315 revolutions per minute to a minimum of 8500 ± 380 revolutions per minute. Reductions in pump speed led to increases in pulse pressure (high versus low speed: 17 ± 7 versus 26 ± 12 mm Hg; P<0.01), distension of the carotid artery, and carotid arterial wall tension (P<0.05 for all measures). In addition, MSNA was reduced (high versus low speed: 41 ± 15 versus 33 ± 16 bursts per minute; P<0.01) despite a reduction in mean arterial pressure and was inversely related to pulse pressure (P=0.037). Among subjects with continuous-flow left ventricular assist devices, the restoration of pulsatile flow through modulations in pump speed leads to increased distortion of the arterial baroreceptors with a subsequent decline in MSNA. Additional study is needed to determine whether reduction of MSNA in this setting leads to improved outcomes. © 2015 American Heart Association, Inc.

Calculation of the ALMA Risk of Right Ventricular Failure After Left Ventricular Assist Device Implantation.

PubMed

Loforte, Antonio; Montalto, Andrea; Musumeci, Francesco; Amarelli, Cristiano; Mariani, Carlo; Polizzi, Vincenzo; Lilla Della Monica, Paola; Grigioni, Francesco; Di Bartolomeo, Roberto; Marinelli, Giuseppe

2018-05-08

Right ventricular failure after continuous-flow left ventricular assist device (LVAD) implantation is still an unsolved issue and remains a life-threatening event for patients. We undertook this study to determine predictors of the patients who are candidates for isolated LVAD therapy as opposed to biventricular support (BVAD). We reviewed demographic, echocardiographic, hemodynamic, and laboratory variables for 258 patients who underwent both isolated LVAD implantation and unplanned BVAD because of early right ventricular failure after LVAD insertion, between 2006 and 2017 (LVAD = 170 and BVAD = 88). The final study patients were randomly divided into derivation (79.8%, n = 206) and validation (20.1%, n = 52) cohorts. Fifty-seven preoperative risk factors were compared between patients who were successfully managed with an LVAD and those who required a BVAD. Nineteen variables demonstrated statistical significance on univariable analysis. Multivariable logistic regression analysis identified destination therapy (odds ratio [OR] 2.0 [1.7-3.9], p = 0.003), a pulmonary artery pulsatility index <2 (OR 3.3 [1.7-6.1], p = 0.001), a right ventricle/left ventricle end-diastolic diameter ratio >0.75 (OR 2.7 [1.5-5.5], p = 0.001), an right ventricle stroke work index <300 mm Hg/ml/m (OR 4.3 [2.5-7.3], p < 0.001), and a United Network for Organ Sharing modified Model for End-Stage Liver Disease Excluding INR score >17 (OR 3.5 [1.9-6.9], p < 0.001) as the major predictors of the need for BVAD. Using these data, we propose a simple risk calculator to determine the suitability of patients for isolated LVAD support in the era of continuous-flow mechanical circulatory support devices.

Use of a Left Ventricular Assist Device as a Bridge to Transplantation in a Pediatric Patient

PubMed Central

Frazier, O.H.; Bricker, J. Timothy; Macris, Michael P.; Cooley, Denton A.

1989-01-01

Despite many advances in heart transplantation and in mechanical circulatory support, the benefits of staged cardiac transplantation have not been extended to the pediatric transplant recipient, chiefly because implantable circulatory assist devices are still too large. Extracorporeal devices, however, can overcome this impediment. Here we report the 1st case, to our knowledge, in which an extracorporeal left ventricular assist device has been used in a child to support circulation prior to cardiac transplantation. The patient was a 9-year-old boy in New York Heart Association functional class IV, with congestive heart failure as a result of idiopathic biventricular cardiomegaly. In mid-May of 1987, while awaiting a suitable donor, he suffered severe oliguria after an episode of circulatory arrest. Therefore we decided to maintain his circulation—and consequently his peripheral organ function—with an extracorporeal left ventricular assist device. After establishing cardiopulmonary bypass under normothermia and without cardiac arrest, we established flow from the left ventricle through a 36-Fr wire-reinforced straight cannula to a Biomedicus BP-80 centrifugal force pump, with return to the proximal ascending aorta through a 28-Fr wire-reinforced straight cannula. The patient's hemodynamic course under subsequent mechanical circulatory support was remarkably stable, with controllable systemic hypertension and no evidence of hemolysis. Although cardiac activity was minimal and systemic blood flow nonpulsatile, the patient's renal, pulmonary, and hepatic functions improved, and his peripheral circulation was well preserved. After 12 hours of support, a donor heart became available, and a routine orthotopic cardiac transplant was performed. Upon removal, the left ventricular assist device showed a small amount of thrombus formation. The patient's postoperative recovery has been easily manageable, and 20 months after transplant he enjoys unrestricted physical

14 CFR Appendix A to Part 1250 - NASA Federal Financial Assistance to Which This Part Applies

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 5 2012-01-01 2012-01-01 false NASA Federal Financial Assistance to Which... ADMINISTRATION NONDISCRIMINATION IN FEDERALLY-ASSISTED PROGRAMS OF NASA-EFFECTUATION OF TITLE VI OF THE CIVIL RIGHTS ACT OF 1964 Pt. 1250, App. A Appendix A to Part 1250—NASA Federal Financial Assistance to Which...

14 CFR Appendix A to Part 1250 - NASA Federal Financial Assistance to Which This Part Applies

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false NASA Federal Financial Assistance to Which... ADMINISTRATION NONDISCRIMINATION IN FEDERALLY-ASSISTED PROGRAMS OF NASA-EFFECTUATION OF TITLE VI OF THE CIVIL RIGHTS ACT OF 1964 Pt. 1250, App. A Appendix A to Part 1250—NASA Federal Financial Assistance to Which...

14 CFR Appendix A to Part 1250 - NASA Federal Financial Assistance to Which This Part Applies

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false NASA Federal Financial Assistance to Which... ADMINISTRATION NONDISCRIMINATION IN FEDERALLY-ASSISTED PROGRAMS OF NASA-EFFECTUATION OF TITLE VI OF THE CIVIL RIGHTS ACT OF 1964 Pt. 1250, App. A Appendix A to Part 1250—NASA Federal Financial Assistance to Which...

Device Management and Flow Optimization on Left Ventricular Assist Device Support.

PubMed

Tchoukina, Inna; Smallfield, Melissa C; Shah, Keyur B

2018-07-01

The authors discuss principles of continuous flow left ventricular assist device (LVAD) operation, basic differences between the axial and centrifugal flow designs and hemodynamic performance, normal LVAD physiology, and device interaction with the heart. Systematic interpretation of LVAD parameters and recognition of abnormal patterns of flow and pulsatility on the device interrogation are necessary for clinical assessment of the patient. Optimization of pump flow using LVAD parameters and echocardiographic and hemodynamics guidance are reviewed. Copyright © 2018 Elsevier Inc. All rights reserved.

Left Ventricular Assist Device Implantation with Concomitant Aortic Valve and Ascending Aortic Replacement.

PubMed

Huenges, Katharina; Panholzer, Bernd; Cremer, Jochen; Haneya, Assad

2018-01-01

Left ventricular assist device (LVAD) is nowadays a routine therapy for patients with advanced heart failure. We present the case of a 74-year-old male patient who was admitted to our center with terminal heart failure in dilated cardiomyopathy and ascending aortic aneurysm with aortic valve regurgitation. The LVAD implantation with simultaneous aortic valve and supracoronary ascending aortic replacement was successfully performed.

From Catheters To Ventricular Assist Devices: 60 Years of Cardiovascular Experiences With William L. Winters, JR., M.D.

PubMed

Winters, W L

2015-01-01

Automatic typewriters, transistor radios, microfiche, black and white television…while considered high-tech in the 1950s, these technologies seem limited when viewed from the 21st century. The same is true for cardiovascular medicine, which back then relied on electrocardiograms and X-rays for most diagnoses. In the 60 years since, advances in medical capabilities have progressed at a staggering pace. Patient research that once required months poring over paper charts is now reduced to hours using electronic medical record databases. Diagnostic images that once took days to process can now be accessed instantly through ultrasound and magnetic resonance imaging. While a half-century ago no one would have imagined accessing any and all information with a 5-second Google search, so too would noninvasive heart surgery been considered unimaginable. Since the 1950s when he graduated from medical school, William L. Winters, Jr., has been a first-hand witness to breathtaking innovations in cardiovascular medicine-both globally and in Houston. Author of Houston Hearts: A History of Cardiovascular Surgery and Medicine at Houston Methodist DeBakey Heart & Vascular Center and long-time medical editor of the Methodist DeBakey Cardiovascular Journal, Dr. Winters sat down with the journal editors this past April to share his insights from the last half-century of medical practice.

Novel temporary left ventricular assist system with hydrodynamically levitated bearing pump for bridge to decision: initial preclinical assessment in a goat model.

PubMed

Kishimoto, Satoru; Takewa, Yoshiaki; Tsukiya, Tomonori; Mizuno, Toshihide; Date, Kazuma; Sumikura, Hirohito; Fujii, Yutaka; Ohnuma, Kentaro; Togo, Konomi; Katagiri, Nobumasa; Naito, Noritsugu; Kishimoto, Yuichiro; Nakamura, Yoshinobu; Nishimura, Motonobu; Tatsumi, Eisuke

2018-03-01

The management of heart failure patients presenting in a moribund state remains challenging, despite significant advances in the field of ventricular assist systems. Bridge to decision involves using temporary devices to stabilize the hemodynamic state of such patients while further assessment is performed and a decision can be made regarding patient management. We developed a new temporary left ventricular assist system employing a disposable centrifugal pump with a hydrodynamically levitated bearing. We used three adult goats (body weight, 58-68 kg) to investigate the 30-day performance and hemocompatibility of the newly developed left ventricular assist system, which included the pump, inflow and outflow cannulas, the extracorporeal circuit, and connectors. Hemodynamic, hematologic, and blood chemistry measurements were investigated as well as end-organ effect on necropsy. All goats survived for 30 days in good general condition. The blood pump was operated at a rotational speed of 3000-4500 rpm and a mean pump flow of 3.2 ± 0.6 L min. Excess hemolysis, observed in one goat, was due to the inadequate increase in pump rotational speed in response to drainage insufficiency caused by continuous contact of the inflow cannula tip with the left ventricular septal wall in the early days after surgery. At necropsy, no thrombus was noted in the pump, and no damage caused by mechanical contact was found on the bearing. The newly developed temporary left ventricular assist system using a disposable centrifugal pump with hydrodynamic bearing demonstrated consistent and satisfactory hemodynamic performance and hemocompatibility in the goat model.

Left Ventricular Assist Device Implantation with Concomitant Aortic Valve and Ascending Aortic Replacement

PubMed Central

Panholzer, Bernd; Cremer, Jochen; Haneya, Assad

2018-01-01

Left ventricular assist device (LVAD) is nowadays a routine therapy for patients with advanced heart failure. We present the case of a 74-year-old male patient who was admitted to our center with terminal heart failure in dilated cardiomyopathy and ascending aortic aneurysm with aortic valve regurgitation. The LVAD implantation with simultaneous aortic valve and supracoronary ascending aortic replacement was successfully performed. PMID:29552039

Myocardial recovery during mechanical circulatory support: long-term outcome and elective ventricular assist device implantation to promote recovery as a treatment goal.

PubMed

Dandel, Michael; Hetzer, Roland

2015-01-01

Even after incomplete myocardial recovery during mechanical circulatory support, long-term survival rates after ventricular assist device (VAD) explantation can be better than those expected after heart transplantation even for patients with chronic non-ischemic cardiomyopathy as the underlying cause for VAD implantation. The elective therapeutic use of ventricular assist devices for heart failure reversal in its early stage is a future goal. It may be possible to achieve it by developing tools to predict heart failure reversibility even before ventricular assist device implantation and increasing the number of weaning candidates by improvement of adjunctive therapies to optimize unloading-promoted recovery.  Special attention is focused on the long-term stability of cardiac remission after VAD removal, the clinical relevance unloading-promoted myocardial recovery and on the current knowledge about a potential prediction of myocardial recovery during long-term VAD support already before VAD implantation.

Left Ventricular Assist Devices

PubMed Central

2004-01-01

Executive Summary Objective The objective of this health technology policy assessment was to determine the effectiveness and cost-effectiveness of using implantable ventricular assist devices in the treatment of end-stage heart failure. Heart Failure Heart failure is a complex syndrome that impairs the ability of the heart to maintain adequate blood circulation, resulting in multiorgan abnormalities and, eventually, death. In the period of 1994 to 1997, 38,702 individuals in Ontario had a first hospital admission for heart failure. Despite reported improvement in survival, the five-year mortality rate for heart failure is about 50%. For patients with end-stage heart failure that does not respond to medical therapy, surgical treatment or traditional circulatory assist devices, heart transplantation (in appropriate patients) is the only treatment that provides significant patient benefit. Heart Transplant in Ontario With a shortage in the supply of donor hearts, patients are waiting longer for a heart transplant and may die before a donor heart is available. From 1999 to 2003, 55 to 74 people received a heart transplant in Ontario each year. Another 12 to 21 people died while waiting for a suitable donor heart. Of these, 1 to 5 deaths occurred in people under 18 years old. The rate-limiting factor in heart transplant is the supply of donor hearts. Without an increase in available donor hearts, attempts at prolonging the life of some patients on the transplant wait list could have a harmful effect on other patients that are being pushed down the waiting list (knock on effect). LVAD Technology Ventricular assist devices [VADs] have been developed to provide circulatory assistance to patients with end-stage heart failure. These are small pumps that usually assist the damaged left ventricle [LVADs] and may be situated within the body (intracorporeal] or outside the body [extracorporeal). Some of these devices were designed for use in the right ventricle [RVAD] or both

Novel nonsurgical left ventricular assist device and system.

PubMed

Misiri, Juna; DeSimone, Christopher V; Park, Soon J; Kushwaha, Sudhir S; Friedman, Paul A; Bruce, Charles J; Asirvatham, Samuel J

2013-01-01

Treatment options for advanced stages of congestive heart failure remain limited. Left ventricular assist devices (LVADs) have emerged as a means to support failing circulation. However, these devices are not without significant risk such as major open chest surgery. We utilized a novel approach for device placement at the aorto-left atria continuity as a site to create a conduit capable of accommodating a percutaneous LVAD system. We designed and developed an expandable nitinol based device for placement at this site to create a shunt between the LA and aorta. Our experiments support this anatomic location as an accessible and feasible site for accommodation of an entirely percutaneous LVAD. The novelty of this approach would bypass the left ventricle, and thereby minimize complications and morbidities associated with current LVAD placement. Copyright © 2013 Elsevier Inc. All rights reserved.

Risk assessment and comparative effectiveness of left ventricular assist device and medical management in ambulatory heart failure patients: design and rationale of the ROADMAP clinical trial.

PubMed

Rogers, Joseph G; Boyle, Andrew J; O'Connell, John B; Horstmanshof, Douglas A; Haas, Donald C; Slaughter, Mark S; Park, Soon J; Farrar, David J; Starling, Randall C

2015-02-01

Mechanical circulatory support is now a proven therapy for the treatment of patients with advanced heart failure and cardiogenic shock. The role for this therapy in patients with less severe heart failure is unknown. The objective of this study is to examine the impact of mechanically assisted circulation using the HeartMate II left ventricular assist device in patients who meet current US Food and Drug Administration-defined criteria for treatment but are not yet receiving intravenous inotropic therapy. This is a prospective, nonrandomized clinical trial of 200 patients treated with either optimal medical management or a mechanical circulatory support device. This trial will be the first prospective clinical evaluation comparing outcomes of patients with advanced ambulatory heart failure treated with either ongoing medical therapy or a left ventricular assist device. It is anticipated to provide novel insights regarding relative outcomes with each treatment and an understanding of patient and provider acceptance of the ventricular assist device therapy. This trial will also provide information regarding the risk of events in "stable" patients with advanced heart failure and guidance for the optimal timing of left ventricular assist device therapy. Copyright © 2014 Elsevier Inc. All rights reserved.

Concomitant transcatheter aortic valve and left ventricular assist device implantation.

PubMed

Baum, Christina; Seiffert, Moritz; Treede, Hendrik; Reichenspurner, Hermann; Deuse, Tobias

2013-01-01

Relevant aortic regurgitation (AR) requires surgical repair at the time of left ventricular assist device (LVAD) implantation to reduce recirculation and ensure adequate forward flow. We report here on a patient with moderate AR in a noncalcified aortic valve and extensive calcification of the ascending aorta. The latter precluded aortic-crossclamping and, thus, surgical intervention on the aortic valve. Although there were no valvular or annular calcifications, a JenaValve transcatheter heart valve was successfully placed transapically with subsequent LVAD implantation in one operation. We believe concomitant transcatheter aortic valve implantation (TAVI) and LVAD implantation is a promising hybrid procedure, even in patients with pure AR.

Comparison of the effects of continuous and pulsatile left ventricular-assist devices on ventricular unloading using a cardiac electromechanics model

PubMed Central

Lim, Ki Moo; Constantino, Jason; Gurev, Viatcheslav; Zhu, Renjun; Trayanova, Natalia A.

2012-01-01

Left ventricular-assist devices (LVADs) are used to supply blood to the body of patients with heart failure. Pressure unloading is greater for counter-pulsating LVADs than for continuous LVADs. However, several clinical trials have demonstrated that myocardial recovery is similar for both types of LVAD. This study examined the contractile energy consumption of the myocardium with continuous and counter-pulsating LVAD support to ascertain the effect of the different LVADs on myocardial recovery. We used a three-dimensional electromechanical model of canine ventricles, with models of the circulatory system and an LVAD. We compared the left ventricular peak pressure (LVPP) and contractile ATP consumption between pulsatile and continuous LVADs. With the continuous and counter-pulsating LVAD, the LVPP decreased to 46 and 10%, respectively, and contractile ATP consumption decreased to 60 and 50%. The small difference between the contractile ATP consumption of these two types of LVAD may explain the comparable effects of the two types on myocardial recovery. PMID:22076841

Intraoperative Hemodynamic and Echocardiographic Measurements Associated With Severe Right Ventricular Failure After Left Ventricular Assist Device Implantation.

PubMed

Gudejko, Michael D; Gebhardt, Brian R; Zahedi, Farhad; Jain, Ankit; Breeze, Janis L; Lawrence, Matthew R; Shernan, Stanton K; Kapur, Navin K; Kiernan, Michael S; Couper, Greg; Cobey, Frederick C

2018-06-05

Severe right ventricular failure (RVF) after left ventricular assist device (LVAD) implantation increases morbidity and mortality. We investigated the association between intraoperative right heart hemodynamic data, echocardiographic parameters, and severe versus nonsevere RVF. A review of LVAD patients between March 2013 and March 2016 was performed. Severe RVF was defined by the need for a right ventricular mechanical support device, inotropic, and/or inhaled pulmonary vasodilator requirements for >14 days. From a chart review, the right ventricular failure risk score was calculated and right heart hemodynamic data were collected. Pulmonary artery pulsatility index (PAPi) [(pulmonary artery systolic pressure - pulmonary artery diastolic pressure)/central venous pressure (CVP)] was calculated for 2 periods: (1) 30 minutes before cardiopulmonary bypass (CPB) and (2) after chest closure. Echocardiographic data were recorded pre-CPB and post-CPB by a blinded reviewer. Univariate logistic regression models were used to examine the performance of hemodynamic and echocardiographic metrics. A total of 110 LVAD patients were identified. Twenty-five did not meet criteria for RVF. Of the remaining 85 patients, 28 (33%) met criteria for severe RVF. Hemodynamic factors associated with severe RVF included: higher CVP values after chest closure (18 ± 9 vs 13 ± 5 mm Hg; P = .0008) in addition to lower PAPi pre-CPB (1.2 ± 0.6 vs 1.7 ± 1.0; P = .04) and after chest closure (0.9 ± 0.5 vs 1.5 ± 0.8; P = .0008). Post-CPB echocardiographic findings associated with severe RVF included: larger right atrial diameter major axis (5.4 ± 0.9 vs 4.9 ± 1.0 cm; P = .03), larger right ventricle end-systolic area (22.6 ± 8.4 vs 18.5 ± 7.9 cm; P = .03), lower fractional area of change (20.2 ± 10.8 vs 25.9 ± 12.6; P = .04), and lower tricuspid annular plane systolic excursion (0.9 ± 0.2 vs 1.1 ± 0.3 cm; P = .008). Right ventricular failure risk score was not a significant predictor of

Implantation of a HeartMate II left ventricular assist device via left thoracotomy.

PubMed

Cho, Yang Hyun; Deo, Salil V; Schirger, John A; Pereira, Naveen L; Stulak, John M; Park, Soon J

2012-11-01

Left thoracotomy was used as an approach for the implantation of pulsatile ventricular assist devices. Avoiding the standard approach of median sternotomy is attractive in patients undergoing complicated redo cardiac surgery, especially with prior mediastinal radiation. We report a case of the use of left thoracotomy for the implantation of the HeartMate II axial-flow pump. Copyright © 2012 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Flow Visualization Studies in the Novacor Left Ventricular Assist System CRADA PC91-002, Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borovetz, H.S.; Shaffer, F.; Schaub, R.

This paper discusses a series of experiments to visualize and measure flow fields in the Novacor left ventricular assist system (LVAS). The experiments utilize a multiple exposure, optical imaging technique called fluorescent image tracking velocimetry (FITV) to hack the motion of small, neutrally-buoyant particles in a flowing fluid.

Design of a right ventricular mock circulation loop as a test bench for right ventricular assist devices.

PubMed

Mueller, Indra; Jansen-Park, So-Hyun; Neidlin, Michael; Steinseifer, Ulrich; Abel, Dirk; Autschbach, Rüdiger; Rossaint, Rolf; Schmitz-Rode, Thomas; Sonntag, Simon Johannes

2017-04-01

Right heart failure (RHF), e.g. due to pulmonary hypertension (PH), is a serious health issue with growing occurrence and high mortality rate. Limited efficacy of medication in advanced stages of the disease constitutes the need for mechanical circulatory support of the right ventricle (RV). An essential contribution to the process of developing right ventricular assist devices (RVADs) is the in vitro test bench, which simulates the hemodynamic behavior of the native circulatory system. To model healthy and diseased arterial-pulmonary hemodynamics in adults (mild and severe PH and RHF), a right heart mock circulation loop (MCL) was developed. Incorporating an anatomically shaped silicone RV and a silicone atrium, it not only enables investigations of hemodynamic values but also suction events or the handling of minimal invasive RVADs in an anatomical test environment. Ventricular pressure-volume loops of all simulated conditions as well as pressure and volume waveforms were recorded and compared to literature data. In an exemplary test, an RVAD was connected to the apex to further test the feasibility of studying such devices with the developed MCL. In conclusion, the hemodynamic behavior of the native system was well reproduced by the developed MCL, which is a useful basis for future RVAD tests.

A motor-driven ventricular assist device controlled with an optical encoder system.

PubMed

Nakamura, T; Hayashi, K; Yamane, H

1993-01-01

An electric motor-driven ventricular assist device has been developed for long-term use inside the body. The system is composed of a pusher-plate-type blood pump and an actuator consisting of an electrical motor and a ball screw. Cyclic change of the direction of motor rotation makes a back-and-forth axial movement of the ball screw shaft. The shaft, which is detached from the pump diaphragm, pushes the diaphragm via a pusher plate to eject blood during systole; blood is sucked by the diaphragm resilience during diastole. Using the output signals from a newly designed, incremental-type, miniature optical rotary encoder mounted inside the actuator, the input voltage of the motor is optimally controlled referring to the phase difference between the current position of the moving rotor and the electrical reference signal of the rotation generated by a microprocessor-based controller. In vitro performance tests indicated that the system fulfills required specifications. The maximum efficiency was 11%, which was about twice as high as that obtained with the previous open-loop prototype system. In the air, the surface temperature of the actuator elevated to 20 degrees C above the room temperature. An acute in vivo test showed its feasibility as a left ventricular assist device. Analysis of the energy loss in each component of the system indicated that redesign and precise assembly of the mechanical parts could increase the system efficiency.

Usability and safety of ventricular assist devices: human factors and design aspects.

PubMed

Geidl, Lorenz; Zrunek, Philipp; Deckert, Zeno; Zimpfer, Daniel; Sandner, Sigrid; Wieselthaler, Georg; Schima, Heinrich

2009-09-01

The purpose of this study was the investigation of the usability and ergonomics of ventricular assist devices (VADs) in everyday usage. Patients with four different VAD types were observed. After implantation, instruction, and discharge from the hospital, the patients returned on a regular basis to the outpatient clinic, where the investigation took place. Data collection took place in two phases. In phase I home-released VAD patients were asked about perceived problems with the system at home. Additionally health-care professionals were interviewed to gather information on frequent VAD inconveniences and shortcomings. This inquiry resulted in a standardized self-assessment questionnaire and a manual skill test, which were performed in phase II by the whole collective (16 patients and ongoing). As a result, 38% of the patients disconnected parts of their system unintentionally at least once. All of them ascribed this problem to their own carelessness. Thirty-eight percent had to replace a cable. Seventy-five percent desired an additional cable strain relief. Thirty-eight percent suffered from rubbing of parts on the body. Sixty-three percent used a separate repository aside from the factory-provided transportation systems. The overall noise emission (pump, ventilators, and alarms) annoyed 56%; however, for 32% the alarm signals were too quiet to wake them up. No correlation between the assessed manual skills and the number of adverse events was found. To conclude, this preliminary study revealed considerable potential for improvements in the usability of ventricular assist systems.

Extracorporeal Life Support Bridge to Ventricular Assist Device: The Double Bridge Strategy.

PubMed

Marasco, Silvana F; Lo, Casey; Murphy, Deirdre; Summerhayes, Robyn; Quayle, Margaret; Zimmet, Adam; Bailey, Michael

2016-01-01

In patients requiring left ventricular assist device (LVAD) support, it can be difficult to ascertain suitability for long-term mechanical support with LVAD and eventual transplantation. LVAD implantation in a shocked patient is associated with increased morbidity and mortality. Interest is growing in the utilization of extracorporeal life support (ECLS) as a bridge-to-bridge support for these critically unwell patients. Here, we reviewed our experience with ECLS double bridging. We hypothesized that ECLS double bridging would stabilize end-organ dysfunction and reduce ventricular assist device (VAD) implant perioperative mortality. We conducted a retrospective review of prospectively collected data for 58 consecutive patients implanted with a continuous-flow LVAD between January 2010 and December 2013 at The Alfred Hospital, Melbourne, Victoria, Australia. Twenty-three patients required ECLS support pre-LVAD while 35 patients underwent LVAD implantation without an ECLS bridge. Preoperative morbidity in the ECLS bridge group was reflected by increased postoperative intensive care duration, blood loss, blood product use, and postoperative renal failure, but without negative impact upon survival when compared with the no ECLS group. ECLS stabilization improved end-organ function pre-VAD implant with significant improvements in hepatic and renal dysfunction. This series demonstrates that the use of ECLS bridge to VAD stabilizes end-organ dysfunction and reduces VAD implant perioperative mortality from that traditionally reported in these "crash and burn" patients. Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Computational study of haemodynamic effects of entry- and exit-tear coverage in a DeBakey type III aortic dissection: technical report.

PubMed

Karmonik, C; Bismuth, J; Shah, D J; Davies, M G; Purdy, D; Lumsden, A B

2011-08-01

Outcome prediction in DeBakey Type III aortic dissections (ADs) remains challenging. Large variations in AD morphology, physiology and treatment exist. Here, we investigate if computational fluid dynamics (CFD) can provide an initial understanding of pressure changes in an AD computational model when covering entry and exit tears and removing the intra-arterial septum (IS). A computational mesh was constructed from magnetic resonance images from one patient (one entrance and one exit tear) and CFD simulations performed (scenario #1). Additional meshes were derived by virtually (1) covering the exit tear (false lumen (FL) thrombus progression) (scenario #2), (2) covering the entrance tear (thoracic endovascular treatment, TEVAR) (scenario #3) and (3) completely removing the IS (fenestration) (scenario #4). Changes in flow patterns and pressures were quantified relative to the initial mesh. Systolic pressures increased for #2 (300 Pa increase) with largest inter-luminal differences distally (2500 Pa). In #3, false lumen pressure decreased essentially to zero. In #4, systolic pressure in combined lumen reduced from 2400 to 800 Pa. CFD results from computational models of a DeBakey type III AD representing separate coverage of entrance and exit tears correlated with clinical experience. The reported results present a preliminary look at a complex clinical problem. Copyright © 2011 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Pulmonary function tests do not predict mortality in patients undergoing continuous-flow left ventricular assist device implantation.

PubMed

Bedzra, Edo K S; Dardas, Todd F; Cheng, Richard K; Pal, Jay D; Mahr, Claudius; Smith, Jason W; Shively, Kent; Masri, S Carolina; Levy, Wayne C; Mokadam, Nahush A

2017-12-01

To investigate the effect of pulmonary function testing on outcomes after continuous flow left ventricular assist device implantation. A total of 263 and 239 patients, respectively, had tests of forced expiratory volume in 1 second and diffusing capacity of the lungs for carbon monoxide preoperatively for left ventricular assist device implantations between July 2005 and September 2015. Kaplan-Meier analysis and multivariable Cox regressions were performed to evaluate mortality. Patients were analyzed in a single cohort and across 5 groups. Postoperative intensive care unit and hospital lengths of stay were evaluated with negative binomial regressions. There is no association of forced expiratory volume in 1 second and diffusing capacity of the lungs for carbon monoxide with survival and no difference in mortality at 1 and 3 years between the groups (log rank P = .841 and .713, respectively). Greater values in either parameter were associated with decreased hospital lengths of stay. Only diffusing capacity of the lungs for carbon monoxide was associated with increased intensive care unit length of stay in the group analysis (P = .001). Ventilator times, postoperative pneumonia, reintubation, and tracheostomy rates were similar across the groups. Forced expiratory volume in 1 second and diffusing capacity of the lungs for carbon monoxide are not associated with operative or long-term mortality in patients undergoing continuous flow left ventricular assist device implantation. These findings suggest that these abnormal pulmonary function tests alone should not preclude mechanical circulatory support candidacy. Copyright © 2017 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Application of the moving-actuator type pump as a ventricular assist device: in vitro and in vivo studies.

PubMed

Lee, H S; Rho, Y R; Park, C Y; Hwang, C M; Kim, W G; Sun, K; Choi, M J; Lee, K K; Cheong, J T; Shim, E B; Min, B G

2002-06-01

A moving actuator type pump has been developed as a multifunctional Korean artificial heart (AnyHeart). The pump consists of a moving actuator as an energy converter, right and left sacs, polymer (or mechanical) valves, and a rigid polyurethane housing. The actuator containing a brushless DC motor moves back and forth on an epicyclical gear train to produce a pendular motion, which compresses both sacs alternately. Of its versatile functions of ventricular assist device and total artificial heart use, we have evaluated the system performance as a single or biventricular assist device through in vitro and in vivo experiments. Pump performance and anatomical feasibility were tested using various animals of different sizes. In the case of single ventricular assist device (VAD) use, one of the sacs remained empty and a mini-compliance chamber was attached to either an outflow or inflow port of the unused sac. The in vitro and in vivo studies show acceptable performance and pump behavior. Further extensive study is required to proceed to human application.

Controversies and Challenges of Ventricular Assist Device Therapy.

PubMed

Lima, Brian; Bansal, Aditya; Abraham, Jacob; Rich, Jonathan D; Lee, Sangjin S; Soleimani, Behzad; Katz, Jason N; Kilic, Ahmet; Young, John S; Patel, Chetan B; Joseph, Susan M

2018-05-15

Left ventricular assist device (LVAD) therapy has emerged as an increasingly vital facet of the treatment algorithm for advanced heart failure. Growing experience with LVAD support has led to substantial improvements in outcomes, with 1-year survival rates approaching that of cardiac transplantation. These therapeutic refinements have engendered growing interests in the potential for expanding the clinical indications for LVAD therapy to patients with less advanced heart failure. The primary obstacles to this evolution of care center largely on the prevention and/or management of the adverse events associated with LVAD therapy along with patient preference. Many programs also face the mounting difficulty of balancing quality outcomes with the increased volume of implants. During the recently assembled Users Meeting organized by St. Jude Medical, heart failure clinicians from nearly 50 LVAD implanting centers discussed these and other challenges and controversies impacting the field. The present review summarizes the key insights gleaned from this meeting. Copyright © 2018 Elsevier Inc. All rights reserved.

No Electromagnetic Interference Occurred in a Patient with a HeartMate II Left Ventricular Assist System and a Subcutaneous Implantable Cardioverter-Defibrillator.

PubMed

Raman, Ajay Sundara; Shabari, Farshad Raissi; Kar, Biswajit; Loyalka, Pranav; Hariharan, Ramesh

2016-04-01

The use of subcutaneous implantable cardioverter-defibrillators is a novel option for preventing arrhythmia-mediated cardiac death in patients who are at risk of endovascular-device infection or in whom venous access is difficult. However, the potential for electromagnetic interference between subcutaneous defibrillators and left ventricular assist devices is largely unknown. We report the case of a 24-year-old man in whom we observed no electromagnetic interference between a subcutaneous implanted cardioverter-defibrillator and a HeartMate II Left Ventricular Assist System, at 3 different pump speeds. To our knowledge, this is the first report of such findings in this circumstance.

Concurrent Left Ventricular Assist Device (LVAD) Implantation and Percutaneous Temporary RVAD Support via CardiacAssist Protek-Duo TandemHeart to Preempt Right Heart Failure.

PubMed

Schmack, Bastian; Weymann, Alexander; Popov, Aron-Frederik; Patil, Nikhil Prakash; Sabashnikov, Anton; Kremer, Jamila; Farag, Mina; Brcic, Andreas; Lichtenstern, Christoph; Karck, Matthias; Ruhparwar, Arjang

2016-05-05

Right ventricular failure (RVF) is an unfortunate complication that continues to limit outcomes following durable left ventricular assist device (LVAD) implantation. Despite several 'RVF risk scores' having been proposed, preoperative prediction of post-LVAD RVF remains a guesstimate at best. Current strategies for institution of temporary RVAD support are invasive, necessitate additional re-thoracotomy, restrict postoperative mobilization, and/or entail prolonged retention of prosthetic material in-situ. The authors propose a novel surgical strategy comprising simultaneous implantation of a permanent LVAD and percutaneous TandemHeart® plus ProtekDuo® to provide temporary RVAD support and preempt RVF in patients with impaired RV function.

Continuous Flow Left Ventricular Assist Device Implant Significantly Improves Pulmonary Hypertension, Right Ventricular Contractility, and Tricuspid Valve Competence

PubMed Central

Atluri, Pavan; Fairman, Alexander S.; MacArthur, John W.; Goldstone, Andrew B.; Cohen, Jeffrey E.; Howard, Jessica L.; Zalewski, Christyna M.; Shudo, Yasuhiro; Woo, Y. Joseph

2014-01-01

Background Continuous flow left ventricular assist devices (CF LVAD) are being implanted with increasing frequency for end-stage heart failure. At the time of LVAD implant, a large proportion of patients have pulmonary hypertension, right ventricular (RV) dysfunction, and tricuspid regurgitation (TR). RV dysfunction and TR can exacerbate renal dysfunction, hepatic dysfunction, coagulopathy, edema, and even prohibit isolated LVAD implant. Repairing TR mandates increased cardiopulmonary bypass time and bicaval cannulation, which should be reserved for the time of orthotopic heart transplantation. We hypothesized that CF LVAD implant would improve pulmonary artery pressures, enhance RV function, and minimize TR, obviating need for surgical tricuspid repair. Methods One hundred fourteen continuous flow LVADs implanted from 2005 through 2011 at a single center, with medical management of functional TR, were retrospectively analyzed. Pulmonary artery pressures were measured immediately prior to and following LVAD implant. RV function and TR were graded according to standard echocardiographic criteria, prior to, immediately following, and long-term following LVAD. Results There was a significant improvement in post-VAD mean pulmonary arterial pressures (26.6 ± 4.9 vs. 30.2 ± 7.4 mmHg, p = 0.008) with equivalent loading pressures (CVP = 12.0 ± 4.0 vs. 12.1 ± 5.1 p = NS). RV function significantly improved, as noted by right ventricular stroke work index (7.04 ± 2.60 vs. 6.05 ± 2.54, p = 0.02). There was an immediate improvement in TR grade and RV function following LVAD implant, which was sustained long term. Conclusion Continuous flow LVAD implant improves pulmonary hypertension, RV function, and tricuspid regurgitation. TR may be managed nonoperatively during CF LVAD implant. PMID:24118109

An optimal controller for an electric ventricular-assist device: theory, implementation, and testing.

PubMed

Klute, G K; Tasch, U; Geselowitz, D B

1992-04-01

This paper addresses the development and testing of an optimal position feedback controller for the Penn State electric ventricular-assist device (EVAD). The control law is designed to minimize the expected value of the EVAD's power consumption for a targeted patient population. The closed-loop control law is implemented on an Intel 8096 microprocessor and in vitro test runs show that this controller improves the EVAD's efficiency by 15-21%, when compared with the performance of the currently used feedforward control scheme.

A new "twist" on right heart failure with left ventricular assist systems.

PubMed

Houston, Brian A; Shah, Keyur B; Mehra, Mandeep R; Tedford, Ryan J

2017-07-01

Despite significant efforts to predict and prevent right heart failure, it remains a leading cause of morbidity and mortality after implantation of left ventricular assist systems (LVAS). In this Perspective, we review the underappreciated anatomic and physiologic principles that govern the relationship between left and right heart function and contribute to this phenomenon. This includes the importance of considering the right ventricle (RV) and pulmonary arterial circuit as a coupled system; the contribution of the left ventricle (LV) to RV contractile function and the potential negative impact of acutely unloading the LV; the influence of the pericardium and ventricular twist on septal function; the role of RV deformation in reduced mechanical efficiency after device placement; and the potential of ongoing stressors of an elevated right-sided preload. We believe an appreciation of these complex issues is required to fully understand the expression of the unique phenotypes of right heart failure after LVAS implantation and for developing better prognostic and therapeutic strategies. Copyright © 2017 International Society for the Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

Monitoring patients with continuous-flow ventricular assist devices outside of the intensive care unit: novel challenges to bedside nursing.

PubMed

O'Shea, Genevieve; Teuteberg, Jeffrey J; Severyn, Donald A

2013-03-01

Ventricular assist devices provide therapeutic options for patients with severe heart failure who have exhausted available medical therapies. With restoration of organ perfusion with ventricular assist devices, the heart failure resolves and quality of life and functional status improve. The current generation of continuous-flow devices present novel challenges to the clinical assessment of patients by substantially reducing or nearly eliminating any palpable pulse. Patients therefore generally have inadequate arterial pulsatility for most noninvasive monitoring devices such as pulse oximeters or automated blood pressure cuffs to work accurately. This article describes the function of continuous-flow devices and how this function affects common monitoring options, as well as how to clinically assess recipients of continuous-flow devices to promptly identify those whose condition may be deteriorating or who may be receiving inadequate perfusion.

Challenges faced in long term ventricular assist device support.

PubMed

Ikegami, Hirohisa; Kurlansky, Paul; Takeda, Koji; Naka, Yoshifumi

2016-08-01

The development of ventricular assist device (VAD) has been one of the revolutionary advancements in end-stage heart failure management. Although the device has developed and improved significantly over the last few decades, we still face multiple challenges. This review will discuss quality of life, survival, and clinically encountered complications in patients with VAD support. The literature was extensively reviewed for studies describing the above topic area. We describe the impact of major challenges faced in VAD support and discuss their future and expectations. Expert commentary: The technological advancement of VADs has contributed to major improvement of overall survival, enhancement of quality of life and decrease of incidence of complications. It is expected that technologies will continue to evolve. At the same time, the indications for and timing of device implantation, and selection of device type are continuously important in clinical practice setting.

Bridge to transplantation with a left ventricular assist device.

PubMed

Jung, Jae Jun; Sung, Kiick; Jeong, Dong Seop; Kim, Wook Sung; Lee, Young Tak; Park, Pyo Won

2012-04-01

A 61-year-old female patient was diagnosed with dilated cardiomyopathy with severe left ventricle dysfunction. Two days after admission, continuous renal replacement therapy was performed due to oliguria and lactic acidosis. On the fifth day, an intra-aortic balloon pump was inserted due to low cardiac output syndrome. Beginning 4 days after admission, she was supported for 15 days thereafter with an extracorporeal left ventricular assist device (LVAD) because of heart failure with multi-organ failure. A heart transplant was performed while the patient was stabilized with the LVAD. She developed several complications after the surgery, such as cytomegalovirus pneumonia, pulmonary tuberculosis, wound dehiscence, and H1N1 infection. On postoperative day 19, she was discharged from the hospital with close follow-up and treatment for infection. She received follow-up care for 10 months without any immune rejection reaction.

The pharmacotherapy implications of ventricular assist device in the patient with end-stage heart failure.

PubMed

Von Ruden, Serena A S; Murray, Margaret A; Grice, Jennifer L; Proebstle, Amy K; Kopacek, Karen J

2012-04-01

Advances in mechanical circulatory support, such as the use of ventricular assist devices (VADs), have become a means for prolonging survival in end-stage heart failure (HF). VADs decrease the symptoms of HF and improve quality of life by replacing some of the work of a failing heart. They unload the ventricle to provide improved cardiac output and end-organ perfusion, resulting in improvement in cardiorenal syndromes and New York Heart Association functional class rating. VADs are currently used asa bridge to heart transplantation, a bridge to recovery of cardiac function, or as destination therapy. Complications of VAD include bleeding, infections, arrhythmias, multiple organ failure, right ventricular failure, and neurological dysfunction. Patients with VAD have unique pharmacotherapeutic requirements in terms of anticoagulation, appropriate antibiotic selection, and continuation of HF medications. Pharmacists in acute care and community settings are well prepared to care for the patient with VAD. These patients require thorough counseling and follow-up with regard to prevention and treatment of infections, appropriate levels of anticoagulation, and maintenance of fluid balance. A basic understanding of this unique therapy can assist pharmacists in attending to the needs of patients with VAD.

Choroidal microcirculation in patients with rotary cardiac assist device.

PubMed

Polska, Elzbieta; Schima, Heinrich; Wieselthaler, Georg; Schmetterer, Leopold

2007-06-01

In recent years, fully implanted rotary blood pumps have been used for long-term cardiac assist in patients with end-stage heart failure. With these pumps, the pulsatility of arterial blood flow and arterial pressure pulse is considerably reduced. Effects on end-organ perfusion, particularly microcirculation, have been assessed. The ocular choroid offers a unique opportunity to study the pulsatile component of blood flow by measurement of fundus pulsation amplitude (FPA) as well as the microcirculation by laser Doppler flowmetry. Both techniques were applied in three male patients with rotary pumps (MicroMed DeBakey VAD), in whom pump velocity was adjusted to four levels of flow between individual minimal need and maximal support. In addition, blood flow velocities in the ophthalmic artery (peak, end-diastolic and mean flow velocity--PSV, EDV and MFV, respectively) were measured using color Doppler imaging. Systolic blood pressure increased by 6 to 22 mm Hg with increasing support. At maximal support FPA was reduced by -60% to -52% as compared with minimal pump support. Blood flow in the choroidal microvasculature, however, did not show relevant changes. A reduction in PSV (-31%, range -47% to -21%) and a pronounced rise in EDV (+93%, range +28% to +147%) was observed, whereas MFV was independent of pump flow. Our data indicate that mean choroidal blood flow is maintained when pump support is varied within therapeutic values, whereas the ratio of pulsatile to non-pulsatile choroidal flow changes. This study shows that, in patients with ventricular assist devices, a normal perfusion rate in the ocular microcirculation is maintained over a wide range of support conditions.

Role of percutaneous veno-arterial extracorporeal membrane oxygenation as bridge to left ventricular assist device.

PubMed

Toda, Koichi; Fujita, Tomoyuki; Seguchi, Osamu; Yanase, Masanobu; Nakatani, Takeshi

2018-03-01

Percutaneous veno-arterial extracorporeal membrane oxygenation (VA-ECMO) provides emergency circulatory support for cardiogenic shock patients and is used as a bridge to a left ventricular assist device (LVAD). The purpose of this study was to determine risk factors for LVAD implantation in patients who required percutaneous VA-ECMO as a bridge to long-term LVAD. We retrospectively investigated 32 consecutive LVAD patients who required percutaneous VA-ECMO as a bridge to long-term LVAD. Twenty-nine patients (91%) were intubated, and their serum creatinine and total bilirubin levels before LVAD implantation were 2.1 ± 2.0 and 3.7 ± 3.7 mg/dl, respectively. Patients were supported by LVAD for 495 ± 393 days, during which 15 died, 6 recovered native cardiac functions and LVAD was explanted, and 11 underwent heart transplantation. Multivariate logistic regression analysis revealed that a preoperative left ventricular end-diastolic diameter (LVDd) ≤54 mm was a significant predictor of 90-day mortality after LVAD implantation (OR 13.64; 95% CI 1.081-172.0; p = 0.0433) and freedom from death during LVAD support was significantly worse in patients with an LVDd ≤54 mm. Furthermore, preoperative LVDd was positively correlated with postoperative right ventricular stroke work index (r = 0.739, p < 0.0001) and patients with an LVDd ≤54 mm had significantly worse postoperative right ventricular, renal, and hepatic functions. We demonstrated that percutaneous VA-ECMO could be utilized as a bridge to long-term LVAD in selected patients. Our results suggest that preoperative LVDd is a useful predictor of mortality and right ventricular function after LVAD implantation in patients requiring VA-ECMO, in whom assessment of right ventricular function is challenging.

Late outcomes of subcostal exchange of the HeartMate II left ventricular assist device: a word of caution.

PubMed

Yu, Sarah N; Takayama, Hiroo; Han, Jiho; Garan, Arthur R; Kurlansky, Paul; Yuzefpolskaya, Melana; Colombo, Paolo C; Naka, Yoshifumi; Takeda, Koji

2018-04-10

Previous studies have shown the usefulness of the subcostal exchange of the HeartMate II left ventricular assist device for device malfunction. However, long-term data are still limited. Between March 2004 and July 2017, 41 of 568 (7.2%) patients who had received a HeartMate II implant at our institution had a device exchange via a subcostal incision. We summarized early and late outcomes. Forty-one patients had a total of 48 subcostal pump exchanges. Indications for device exchange included device thrombosis (n = 31, 76%), driveline infection (n = 2, 5%) and driveline injury (n = 8, 19%). All of the procedures were successful, and there were no in-hospital deaths. A Kaplan-Meier survival curve showed 30-day and 1-year survival rates after subcostal exchange of 100% and 94.6%, respectively. However, 10 (25%) patients had left ventricular assist device-related infections following subcostal exchange that included 7 pump pocket infections and 3 driveline infections. Freedom from left ventricular assist device-related infection at 1 year after subcostal exchange was 79.3%. Thirteen (32%) patients had device malfunction due to pump thrombosis that required a 2nd device exchange. Seven patients had recurrent thrombosis. Three (7%) patients had a stroke. Freedom from device thrombosis and from a stroke event at 1 year was 74.4%. Subcostal pump exchange can be safely performed. However, there is a substantial risk of infection and recurrent thrombosis. Careful follow-up for late complications is mandatory.

Continuous-Flow Left Ventricular Assist Device Support Improves Myocardial Supply:Demand in Chronic Heart Failure.

PubMed

Soucy, Kevin G; Bartoli, Carlo R; Phillips, Dustin; Giridharan, Guruprasad A; Sobieski, Michael A; Wead, William B; Dowling, Robert D; Wu, Zhongjun J; Prabhu, Sumanth D; Slaughter, Mark S; Koenig, Steven C

2017-06-01

Continuous-flow left ventricular assist devices (CF LVADs) are rotary blood pumps that improve mean blood flow, but with potential limitations of non-physiological ventricular volume unloading and diminished vascular pulsatility. In this study, we tested the hypothesis that left ventricular unloading with increasing CF LVAD flow increases myocardial flow normalized to left ventricular work. Healthy (n = 8) and chronic ischemic heart failure (IHF, n = 7) calves were implanted with CF LVADs. Acute hemodynamics and regional myocardial blood flow were measured during baseline (LVAD off, clamped), partial (2-4 L/min) and full (>4 L/min) LVAD support. IHF calves demonstrated greater reduction of cardiac energy demand with increasing LVAD support compared to healthy calves, as calculated by rate-pressure product. Coronary artery flows (p < 0.05) and myocardial blood flow (left ventricle (LV) epicardium and myocardium, p < 0.05) decreased with increasing LVAD support in normal calves. In the IHF model, blood flow to the septum, LV, LV epicardium, and LV myocardium increased significantly with increasing LVAD support when normalized to cardiac energy demand (p < 0.05). In conclusion, myocardial blood flow relative to cardiac demand significantly increased in IHF calves, thereby demonstrating that CF LVAD unloading effectively improves cardiac supply and demand ratio in the setting of ischemic heart failure.

Ethical analysis of withdrawing ventricular assist device support.

PubMed

Mueller, Paul S; Swetz, Keith M; Freeman, Monica R; Carter, Kari A; Crowley, Mary Eliot; Severson, Cathy J Anderson; Park, Soon J; Sulmasy, Daniel P

2010-09-01

To describe a series of patients with heart failure supported with a ventricular assist device (VAD) who requested (or whose surrogates requested) withdrawal of VAD support and the legal and ethical aspects pertaining to these requests. We retrospectively reviewed the medical records of patients at Mayo Clinic, Rochester, MN, from March 1, 2003, through January 31, 2009, who requested (or whose surrogates requested) withdrawal of VAD support and for whom the requests were fulfilled. We then explored the legal and ethical permissibility of carrying out such requests. The median age of the 14 patients identified (13 men, 1 woman) was 57 years. Requests were made by 2 patients and 12 surrogates. None of the patients' available advance directives mentioned the VAD. For 11 patients, multidisciplinary care conferences were held before withdrawal of VAD support. Only 1 patient had an ethics consultation. All 14 patients died within 1 day of withdrawal of VAD support. Patients have the right to refuse or request the withdrawal of any unwanted treatment, and we argue that this right extends to VAD support. We also argue that the cause of death in these cases is the underlying heart disease, not assisted suicide or euthanasia. Therefore, patients with heart failure supported with VADs or their surrogates may request withdrawal of this treatment. In our view, carrying out such requests is permissible in accordance with the principles that apply to withdrawing other life-sustaining treatments.

Left ventricular assist device implantation in a patient who had previously undergone apical myectomy for hypertrophic cardiomyopathy.

PubMed

Cho, Yang Hyun; Deo, Salil V; Topilsky, Yan; Grogan, Martha A; Park, Soon J

2012-03-01

Apical hypertrophy is a rare variant of hypertropic cardiomyopathy. These patients may present with end-stage congestive heart failure subsequent to long standing diastolic dysfunction. We report the technique for left ventricular assist device insertion in a patient with previous apical myectomy for hypertrophic cardiomyopathy. © 2012 Wiley Periodicals, Inc.

Modeling and control of a brushless DC axial flow ventricular assist device.

PubMed

Giridharan, Guruprasad A; Skliar, Mikhail; Olsen, Donald B; Pantalos, George M

2002-01-01

This article presents an integrated model of the human circulatory system that incorporates circulatory support by a brushless DC axial flow ventricular assist device (VAD), and a feedback VAD controller designed to maintain physiologically sufficient perfusion. The developed integrated model combines a network type model of the circulatory system with a nonlinear dynamic model of the brushless DC pump We show that maintaining a reference differential pressure between the left ventricle and aorta leads to adequate perfusion for different pathologic cases, ranging from normal heart to left heart asystole, and widely varying physical activity scenarios from rest to exercise.

No Electromagnetic Interference Occurred in a Patient with a HeartMate II Left Ventricular Assist System and a Subcutaneous Implantable Cardioverter-Defibrillator

PubMed Central

Raman, Ajay Sundara; Kar, Biswajit; Loyalka, Pranav; Hariharan, Ramesh

2016-01-01

The use of subcutaneous implantable cardioverter-defibrillators is a novel option for preventing arrhythmia-mediated cardiac death in patients who are at risk of endovascular-device infection or in whom venous access is difficult. However, the potential for electromagnetic interference between subcutaneous defibrillators and left ventricular assist devices is largely unknown. We report the case of a 24-year-old man in whom we observed no electromagnetic interference between a subcutaneous implanted cardioverter-defibrillator and a HeartMate II Left Ventricular Assist System, at 3 different pump speeds. To our knowledge, this is the first report of such findings in this circumstance. PMID:27127441

Exercise therapy for an older patient with left ventricular assist device.

PubMed

Park, Won Hah; Seo, Yong Gon; Sung, Ji Dong

2014-06-01

A left ventricular assist device (LVAD) is a mechanical circulation support implanted for patients with end-stage heart failure. It may be used either as a bridge to cardiac transplantation or as a destination therapy. The health of a 75-year-old man with a medical history of systolic heart failure worsened. Therefore, he was recommended to have implanted a LVAD (Thoratec Corp.) as a destination therapy. After the surgery, he was enrolled in patient cardiac rehabilitation for the improvement of dyspnea and exercise capacity. In results, there is an improvement on his exercise capacity and quality of life. For the first time in Korea, we reported a benefit of exercise therapy after being implanted with a LVAD.

Focused review on transthoracic echocardiographic assessment of patients with continuous axial left ventricular assist devices.

PubMed

Topilsky, Yan; Maltais, Simon; Oh, Jae K; Atchison, Fawn W; Perrault, Louis P; Carrier, Michel; Park, Soon J

2011-02-08

Left ventricular assist devices (LVADs) are systems for mechanical support for patients with end-stage heart failure. Preoperative, postoperative and comprehensive followup with transthoracic echocardiography has a major role in LVAD patient management. In this paper, we will present briefly the hemodynamics of axial-flow LVAD, the rationale, and available data for a complete and organized echocardiographic assessment in these patients including preoperative assessment, postoperative and long-term evaluation.

Evaluation of right ventricular function using liver stiffness in patients with left ventricular assist device.

PubMed

Kashiyama, Noriyuki; Toda, Koichi; Nakamura, Teruya; Miyagawa, Shigeru; Nishi, Hiroyuki; Yoshikawa, Yasushi; Fukushima, Satsuki; Saito, Shunsuke; Yoshioka, Daisuke; Sawa, Yoshiki

2017-04-01

Although right ventricular failure (RVF) is a major concern after left ventricular assist device (LVAD) implantation, methodologies to evaluate RV function remain limited. Liver stiffness (LS), which is closely related to right-sided filling pressure and may indicate RVF severity, could be non-invasively and repeatedly assessed using transient elastography. Here we investigated the suitability of LS as a parameter of RV function in pre- and post-LVAD periods. The study included 55 patients with LVAD implantation as a bridge to transplantation between 2011 and 2015 whose LS was assessed using transient elastography. Seventeen patients presented with RVF, defined as requiring inotropic support for ≥30 days, nitric oxygen inhalation for ≥5 days, and/or mechanical RV support following LVAD implantation. Survival of patients with RVF was significantly worse compared with that of patients without RVF. Multivariate logistic regression analysis identified preoperative LS, LV diastolic dimension, RV stroke work index, and dilated phase of hypertrophic cardiomyopathy aetiology as significant risk factors; the combination of these parameters could improve predictive power of post-LVAD RVF with areas under the curve of 0.89. Furthermore, LS was significantly decreased by LV unloading and significantly correlated with right-sided filling pressure. In addition to dilated hypertrophic cardiomyopathy aetiology, reduced RV stroke work index and small LV dimension, we demonstrated that non-invasively measured LS was a predictor of post-LVAD RVF and can be used as a parameter for the evaluation and optimization of RV function in the perioperative period. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery.

The Provisional Extension To Induce Complete Attachment (PETTICOAT) technique to promote distal aortic remodelling in repair of acute DeBakey type I aortic dissection: preliminary results.

PubMed

Hsu, Hung-Lung; Chen, Yin-Yin; Huang, Chun-Yang; Huang, Jih-Hsin; Chen, Jer-Shen

2016-07-01

To report our preliminary results of an aggressive technique, the Provisional Extension To Induce Complete Attachment (PETTICOAT), in repair of acute DeBakey type I aortic dissection. From April 2014 to November 2014, 18 patients with acute DeBakey type I aortic dissection were reviewed retrospectively. Nine patients underwent open repair combined with proximal stent grafting and distal bare stenting (PETTICOAT group). For comparison, another 9 patients underwent open repair combined with proximal stent grafting (NON-PETTICOAT group) were included. Open repair entailed ascending aorta plus total arch replacement under circulatory arrest, with variable aortic root work. Mortality and morbidity were recorded, and computed tomography was performed to evaluate the aortic remodelling at 6 months postoperatively. Preoperative parameters were similar. In the PETTICOAT group, one early mortality was noted. One complication of cardiac tamponade and sternal wound infection led to reopen surgeries. In the NON-PETTICOAT group, one case of transient ischaemic attack took place. Compared with the NON-PETTICOAT group, a significant increase in diameter of true lumen (median, 0.6 vs 0.1 mm, P < 0.01) and a decrease in diameter of false lumen (FL; median, -0.9 vs 0.0 mm, P < 0.01) at the level of lowest renal artery were noted in the PETTICOAT group. Moreover, significant FL volume regression (median, -102.0 vs -42.2 mm(3), P = 0.03) was observed in the PETTICOAT group. More cases of total thrombosis or regression of FL down to the level of renal artery were also noted in the PETTICOAT group (5/8 vs 0/9, P < 0.01). Two patients of the NON-PETTICOAT group received endovascular distal aortic reintervention at 6 months. The PETTICOAT technique in the management of acute DeBakey type I dissection is a feasible and promising method to promote distal aortic remodelling. However, outcomes are preliminary and further follow-up is required. © The Author 2016. Published by Oxford University

Remote monitoring of left ventricular assist device parameters after HeartAssist-5 implantation.

PubMed

Pektok, Erman; Demirozu, Zumrut Tuba; Arat, Nurcan; Yildiz, Omer; Oklu, Emine; Eker, Deniz; Ece, Ferah; Ciftci, Cavlan; Yazicioglu, Nuran; Bayindir, Osman; Kucukaksu, Deniz Suha

2013-09-01

Although several left ventricular assist devices (LVADs) have been used widely, remote monitoring of LVAD parameters has been available only recently. We present our remote monitoring experience with an axial-flow LVAD (HeartAssist-5, MicroMed Cardiovascular, Inc., Houston, TX, USA). Five consecutive patients who were implanted a HeartAssist-5 LVAD because of end-stage heart failure due to ischemic (n=4) or idiopathic (n=1) cardiomyopathy, and discharged from hospital between December 2011 and January 2013 were analyzed. The data (pump speed, pump flow, power consumption) obtained from clinical visits and remote monitoring were studied. During a median follow-up of 253 (range: 80-394) days, fine tuning of LVADs was performed at clinical visits. All patients are doing well and are in New York Heart Association Class-I/II. A total of 39 alarms were received from three patients. One patient was hospitalized for suspected thrombosis and was subjected to physical examinations as well as laboratory and echocardiographic evaluations; however, no evidence of thrombus washout or pump thrombus was found. The patient was treated conservatively. Remaining alarms were due to insufficient water intake and were resolved by increased water consumption at night and summer times, and fine tuning of pump speed. No alarms were received from the remaining two patients. We believe that remote monitoring is a useful technology for early detection and treatment of serious problems occurring out of hospital thereby improving patient care. Future developments may ease troubleshooting, provide more data from the patient and the pump, and eventually increase physician and patient satisfaction. Despite all potential clinical benefits, remote monitoring should be taken as a supplement to rather than a substitute for routine clinical visits for patient follow-up. © 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation.

[Anaesthetic management in left ventricular assist device implantation as destination therapy: Our first experience].

PubMed

del Barrio Gómez, E; Rodríguez, J M; Martínez, S; García, E; Vargas, M C; Sastre, J A

2016-03-01

Left ventricular assist devices have emerged as one of the main therapies of advanced cardiac failure due the increase of this disease and lack of organ supply for cardiac transplantation. The anaesthetic management is described on a patient without cardiac transplantation criteria. The device was successfully implanted as a destination therapy. Copyright © 2015 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

Early Feasibility Testing and Engineering Development of the Transapical Approach for the HeartWare MVAD Ventricular Assist System

PubMed Central

Tamez, Daniel; LaRose, Jeffrey A.; Shambaugh, Charles; Chorpenning, Katherine; Soucy, Kevin G; Sobieski, Michael A; Sherwood, Leslie; Giridharan, Guruprasad A; Monreal, Gretel; Koenig, Steven C; Slaughter, Mark S

2014-01-01

Implantation of ventricular assist devices (VADs) for treatment of end-stage heart failure (HF) falls decidedly short of clinical demand, which exceeds 100,000 HF patients per year. VAD implantation often requires major surgical intervention with associated risk of adverse events and long recovery periods. To address these limitations, HeartWare, Inc. (Miami Lakes, FL) has developed a platform of miniature ventricular devices with progressively reduced surgical invasiveness and innovative patient peripherals. One surgical implant concept is a transapical version of the miniaturized left ventricular assist device (MVAD). The HeartWare MVAD Pump® is a small, continuous flow, full-support device that has a displacement volume of 22mL. A new cannula configuration has been developed for transapical implantation, where the outflow cannula is positioned across the aortic valve. The two primary objectives for this feasibility study were to evaluate anatomic fit and surgical approach and efficacy of the transapical MVAD configuration. Anatomic fit and surgical approach were demonstrated using human cadavers (n=4). Efficacy was demonstrated in acute (n =2) and chronic (n = 1) bovine model experiments and assessed by improvements in hemodynamics, biocompatibility, flow dynamics, and histopathology. Potential advantages of the MVAD Pump include flow support in the same direction as the native ventricle, elimination of cardiopulmonary bypass, and minimally-invasive implantation. PMID:24399057

Prospective Randomized Evaluation of Implantable Cardioverter-Defibrillator Programming in Patients With a Left Ventricular Assist Device.

PubMed

Richardson, Travis D; Hale, Leslie; Arteaga, Christopher; Xu, Meng; Keebler, Mary; Schlendorf, Kelly; Danter, Matthew; Shah, Ashish; Lindenfeld, JoAnn; Ellis, Christopher R

2018-02-23

Ventricular arrhythmias are common in patients with left ventricular assist devices (LVADs) but are often hemodynamically tolerated. Optimal implantable cardioverter defibrillator (ICD) tachy-programming strategies in patients with LVAD have not been determined. We sought to determine if an ultra-conservative ICD programming strategy in patients with LVAD affects ICD shocks. Adult patients with an existing ICD undergoing continuous flow LVAD implantation were randomized to standard ICD programming by their treating physician or an ultra-conservative ICD programming strategy utilizing maximal allowable intervals to detection in the ventricular fibrillation and ventricular tachycardia zones with use of ATP. Patients with cardiac resynchronization therapy (CRT) devices were also randomized to CRT ON or OFF. Patients were followed a minimum of 6 months. The primary outcome was time to first ICD shock. Among the 83 patients studied, we found no statistically significant difference in time to first ICD shock or total ICD shocks between groups. In the ultra-conservative group 16% of patients experienced at least one shock compared with 21% in the control group ( P =0.66). There was no difference in mortality, arrhythmic hospitalization, or hospitalization for heart failure. In the 41 patients with CRT ICDs fewer shocks were observed with CRT-ON but this was not statistically significant: 10% of patients with CRT-ON (n=21) versus 38% with CRT-OFF (n=20) received shocks ( P =0.08). An ultra-conservative programming strategy did not reduce ICD shocks. Programming restrictions on ventricular tachycardia and ventricular fibrillation zone therapy should be reconsidered for the LVAD population. The role of CRT in patients with LVAD warrants further investigation. URL: https://www.clinicaltrials.gov. Unique identifier: NCT01977703. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Long-term left ventricular assist device use before transplantation.

PubMed

Sapirstein, J S; Pae, W E; Aufiero, T X; Boehmer, J P; Pierce, W S

1995-01-01

Between September 1992 and April 1995, 19 patients at the authors' institution received pneumatic, pulsatile left ventricular assist devices (LVADs) for bridging to cardiac transplantation. The mean (+/- SD) age of the patients was 51 +/- 14 years (range, 19-64 years). Nine (47%) patients had end-stage idiopathic cardiomyopathy, five (26%) had ischemic cardiomyopathy, and five (26%) other recipients were in cardiogenic shock caused by acute myocardial infarction (AMI). Fifteen (79%) patients were supported with an intraaortic balloon pump or centrifugal LVAD at the time of LVAD insertion (duration, 5.5 +/- 4.1 days). Aprotinin was given to limit bleeding; heparin, followed by warfarin sodium, was used for anticoagulation. A vigorous exercise and nutrition protocol was followed. Cardiac index averaged 2.94 +/- 0.87 L/min/m2 immediately after the implantation procedure. No patient required placement of a right VAD. Average duration of LVAD support was 45 +/- 39 days (range, 3-153 days). Major complications included bleeding requiring reoperation (three patients); cerebrovascular accident (three patients); and severe dysrhythmias requiring direct current cardioversion (four patients). Fourteen (74%) patients underwent transplantation, with one patient still being mechanically supported. All of the patients receiving transplants were discharged from the hospital. Of the individuals who died while supported with the LVAD, 75% were patients with AMI. Timely application of LVADs as part of the interdisciplinary management of end-stage heart disease has generated excellent results for transplant candidates. Right ventricular dysfunction has not necessitated right VAD placement in the authors' experience. Patients with AMI have a higher risk of death while being supported with the device than do more chronically ill recipients.

Pulsatile operation of a continuous-flow right ventricular assist device (RVAD) to improve vascular pulsatility

PubMed Central

Ng, Boon C.; Timms, Daniel; Cohn, William E.

2018-01-01

Despite the widespread acceptance of rotary blood pump (RBP) in clinical use over the past decades, the diminished flow pulsatility generated by a fixed speed RBP has been regarded as a potential factor that may lead to adverse events such as vasculature stiffening and hemorrhagic strokes. In this study, we investigate the feasibility of generating physiological pulse pressure in the pulmonary circulation by modulating the speed of a right ventricular assist device (RVAD) in a mock circulation loop. A rectangular pulse profile with predetermined pulse width has been implemented as the pump speed pattern with two different phase shifts (0% and 50%) with respect to the ventricular contraction. In addition, the performance of the speed modulation strategy has been assessed under different cardiovascular states, including variation in ventricular contractility and pulmonary arterial compliance. Our results indicated that the proposed pulse profile with optimised parameters (Apulse = 10000 rpm and ωmin = 3000 rpm) was able to generate pulmonary arterial pulse pressure within the physiological range (9–15 mmHg) while avoiding undesirable pump backflow under both co- and counter-pulsation modes. As compared to co-pulsation, stroke work was reduced by over 44% under counter-pulsation, suggesting that mechanical workload of the right ventricle can be efficiently mitigated through counter-pulsing the pump speed. Furthermore, our results showed that improved ventricular contractility could potentially lead to higher risk of ventricular suction and pump backflow, while stiffening of the pulmonary artery resulted in increased pulse pressure. In conclusion, the proposed speed modulation strategy produces pulsatile hemodynamics, which is more physiologic than continuous blood flow. The findings also provide valuable insight into the interaction between RVAD speed modulation and the pulmonary circulation under various cardiovascular states. PMID:29677212

Postimplant left ventricular assist device fit analysis using three-dimensional reconstruction.

PubMed

Truong, Thang V; Stanfield, J Ryan; Chaffin, John S; Elkins, C Craig; Kanaly, Paul J; Horstmanshof, Douglas A; Long, James W; Snyder, Trevor A

2013-01-01

Left ventricular assist devices (LVADs) are blood pumps that augment the function of the failing heart to improve perfusion, resulting in improved survival. For LVADs to effectively unload the left ventricle, the inflow cannula (IC) should be unobstructed and ideally aligned with the heart's mitral valve (MV). We examined IC orientation deviation from a hypothesized conventional angle (45° right-posterior) and the approximate angle for direct IC-MV alignment in many patients. Three-dimensional anatomic models were created from computed tomography scans for 24 LVAD-implanted patients, and angles were measured between the IC and the apical z-axis in both the coronal and the sagittal planes. Common surgical IC angulation was found to be 22 ± 15° rightward and 21 ± 12° posterior from the apical z-axis; 38% (n = 9) of patients fell in this range. Direct IC-MV angulation was found to be 34 ± 8° rightward and 15 ± 7° posterior; only 8% (n = 2) of patients fell in this range. Rightward deviation toward ventricular septal wall and anterior deviation toward LV anterior freewall are associated with mortalities more so than leftward and posterior deviation. In conclusion, anatomic reconstruction may be a useful preoperative tool to obtain general population and patient-specific alignment for optimal LVAD implantation.

Development of the NEDO implantable ventricular assist device with Gyro centrifugal pump.

PubMed

Yoshikawa, M; Nonaka, K; Linneweber, J; Kawahito, S; Ohtsuka, G; Nakata, K; Takano, T; Schulte-Eistrup, S; Glueck, J; Schima, H; Wolner, E; Nosé, Y

2000-06-01

The Gyro centrifugal pump, PI (permanently implantable) series, is being developed as a totally implantable artificial heart. Our final goal is to establish a "functional TAH," a totally implantable biventricular assist system (BiVAS) with centrifugal pumps. A plastic prototype pump, Gyro PI 601, was evaluated through in vitro and in vivo studies as a single ventricular assist device (VAD). Based upon these results, the pump head material was converted to a titanium alloy, and the actuator was modified. These titanium Gyro pumps, PI 700 series, also were subjected to in vitro and in vivo studies. The Gyro PI 601 and PI 700 series have the same inner dimensions and characteristics, such as the eccentric inlet port, double pivot bearing system, secondary vane, and magnet coupling system; however, the material of the PI 700 is different from the PI 601. The Gyro PI series is driven by the Vienna DC brushless motor actuator. The inlet cannula of the right ventricular assist system (RVAS) specially made for this system consists of 2 parts: a hat-shaped silicone tip biolized with gelatin and an angled wire reinforced tube made of polyvinylchloride. The pump-actuator package was implanted into 8 calves in the preperitoneal space, bypassing from the left ventricle apex to the descending aorta for the left ventricular assist system (LVAS) and bypassing the right ventricle to the main pulmonary artery for the RVAS. According to the PI 601 feasibility protocol, 2 LVAS cases were terminated after 2 weeks, and 1 LVAS case and 1 RVAS were terminated after 1 month. The PI 700 series was implanted into 4 cases: 3 LVAS cases survived for a long term, 2 of them over 200 days (72-283 days), and 1 RVAS case survived for 1 month and was terminated according to the protocol for a short-term antithrombogenic screening and system feasibility study. Regarding power consumption, the plastic pump cases demonstrated from 6.2 to 12.1 W as LVAS and 7.3 W as RVAS, the titanium pump cases showed

Single-centre experience with the Thoratec paracorporeal ventricular assist device for patients with primary cardiac failure.

PubMed

Kirsch, Matthias; Vermes, Emmanuelle; Damy, Thibaud; Nakashima, Kuniki; Sénéchal, Mélanie; Boval, Bernadette; Drouet, Ludovic; Loisance, Daniel

2009-01-01

Temporary mechanical circulatory support may be indicated in some patients with cardiac failure refractory to conventional therapy, as a bridge to myocardial recovery or transplantation. To evaluate outcomes in cardiogenic shock patients managed by the primary use of a paracorporeal ventricular assist device (p-VAD). We did a retrospective analysis of demographics, clinical characteristics and survival of patients assisted with a Thoratec p-VAD. p-VADs were used in 84 patients with cardiogenic shock secondary to acute myocardial infarction (35%), idiopathic (31%) or ischaemic (12%) cardiomyopathy, myocarditis or other causes (23%). Before implantation, 23% had cardiac arrest, 38% were on a ventilator and 31% were on an intra-aortic balloon pump. Cardiac index was 1.6+/-0.5 L/min/m(2) and total bilirubin levels were 39+/-59 micromol/L. During support, 29 patients (35%) died in the intensive care unit and seven (10%) died after leaving. Forty-seven patients (56%) were weaned or transplanted, with one still under support. Despite significantly more advanced preoperative end-organ dysfunction, survival rates were similar in patients with biventricular devices (74%) and those undergoing isolated left ventricular support (24%) (63% versus 45%, respectively; p=0.2). Actuarial survival estimates after transplantation were 78.7+/-6.3%, 73.4+/-6.9% and 62.6+/-8.3% at 1, 3 and 5 years, respectively. Our experience validates the use of p-VAD as a primary device to support patients with cardiogenic shock. In contrast to short-term devices, p-VADs provide immediate ventricular unloading and pulsatile perfusion in a single procedure. Biventricular support should be used liberally in patients with end-organ dysfunction.

A novel method for percutaneous insertion of a right ventricular assist device.

PubMed

Avgerinos, Dimitrios V; DeBois, William; Mongero, Linda; Krieger, Karl; Salemi, Arash

2013-06-01

Right heart failure is a rare but often fatal complication both in the pre- and postoperative setting. Right heart support with a ventricular assist device inserted in the operating room through median sternotomy can be a time-consuming procedure that requires a reoperation for removal. In cases of urgent need of right heart support, a percutaneous technique option may be of benefit. We present our initial experience with a percutaneously inserted right ventricular assist device (RVAD) in an elderly patient with severe right heart failure. An 81-year-old female patient underwent combined aortic and mitral valve replacement at our institution. During the first postoperative evening, the patient sustained sudden cardiovascular collapse and a bedside transesophageal echocardiogram revealed severe right heart failure. A coronary angiogram showed thrombosis of the right coronary artery, which was cleared with a suction device. As a result of the patient's critical condition, it was decided that an RVAD was needed as a bridge to recovery. The patient's condition improved significantly almost immediately. Her right heart function recovered over the next few days and the RVAD was removed at the bedside. She made a complete recovery and was discharged home. This patient is a prime example that a totally RVAD can be inserted in urgent situations easily and safely under fluoroscopic and echocardiographic guidance. More clinical experience with percutaneous RVADs is required to establish this technique as an alternative equivalent to the traditional open method. Right heart failure complicates many heart diseases both in the pre- and the postoperative setting. In cases of urgent need of right heart support, a percutaneous technique of a RVAD is needed for a successful outcome. We present our initial experience with a percutaneously inserted RVAD in an elderly patient with severe postoperative right heart failure.

Left ventricular assist device as destination therapy: application of the payment-by-results approach for the device reimbursement.

PubMed

Messori, Andrea; Trippoli, Sabrina; Bonacchi, Massimo; Sani, Guido

2009-08-01

Value-based methods are increasingly used to reimburse therapeutic innovation, and the payment-by-results approach has been proposed for handling interventions with limited therapeutic evidence. Because most left ventricular assist devices are supported by preliminary efficacy data, we examined the effectiveness data of the HeartMate (Thoratec Corp, Pleasanton, CA) device to explore the application of the payment-by-results approach to these devices and to develop a model for handling reimbursements. According to our model, after establishing the societal economic countervalue for each month of life saved, each patient treated with one such device is associated to the payment of this countervalue for every month of survival lived beyond the final date of estimated life expectancy without left ventricular assist devices. Our base-case analysis, which used the published data of 68 patients who received the HeartMate device, was run with a monthly countervalue of euro 5000, no adjustment for quality of life, and a baseline life expectancy of 150 days without left ventricular assist devices. Sensitivity analysis was aimed at testing the effect of quality of life adjustments and changes in life expectancy without device. In our base-case analysis, the mean total reimbursement per patient was euro 82,426 (range, euro 0 to euro 250,000; N = 68) generated as the sum of monthly payments. This average value was close to the current price of the HeartMate device (euro 75,000). Sensitivity testing showed that the base-case reimbursement of euro 82,426 was little influenced by variations in life expectancy, whereas variations in utility had a more pronounced impact. Our report delineates an innovative procedure for appropriately allocating economic resources in this area of invasive cardiology.

Computational fluid dynamics analysis of a maglev centrifugal left ventricular assist device.

PubMed

Burgreen, Greg W; Loree, Howard M; Bourque, Kevin; Dague, Charles; Poirier, Victor L; Farrar, David; Hampton, Edward; Wu, Z Jon; Gempp, Thomas M; Schöb, Reto

2004-10-01

The fluid dynamics of the Thoratec HeartMate III (Thoratec Corp., Pleasanton, CA, U.S.A.) left ventricular assist device are analyzed over a range of physiological operating conditions. The HeartMate III is a centrifugal flow pump with a magnetically suspended rotor. The complete pump was analyzed using computational fluid dynamics (CFD) analysis and experimental particle imaging flow visualization (PIFV). A comparison of CFD predictions to experimental imaging shows good agreement. Both CFD and experimental PIFV confirmed well-behaved flow fields in the main components of the HeartMate III pump: inlet, volute, and outlet. The HeartMate III is shown to exhibit clean flow features and good surface washing across its entire operating range.

A calf model for left ventricular centrifugal mechanical assist.

PubMed

Mann, F A; Wagner-Mann, C C; Curtis, J J; Demmy, T L; Turk, J R

1996-06-01

The increased use of centrifugal mechanical assist (CMA) for treatment of refractory postcardiotomy cardiogenic shock highlights the need for experimental testing to improve clinical results. This report describes the preoperative conditioning, anesthetic and surgical technique, and postoperative management of a reliable calf model refined in this laboratory for in vivo subchronic (96 h) testing of CMA. Holstein bull calves (2 to 3 months old; mean body weight, 78 kg; n = 35) were instrumented for left ventricular CMA; 4 of these calves were sham-operated controls. Anesthetic recovery and postoperative restraint were accomplished in a specially designed crate to which each calf was preconditioned extensively. Younger calves were more readily conditioned and more tolerant of postoperative restraint than older calves. One calf died of ventricular fibrillation intraoperatively. One calf that had been heparinized developed uncontrollable hemothorax and died 12 h postoperatively. One calf prematurely dislodged his aortic cannula 15 h postoperatively and exsanguinated. Six calves developed pelvic limb paresis or paralysis because of lumbar spinal cord thromboembolism by 36 h postoperatively, and 3 of these calves were sacrificed by 42 h postoperatively. Fifteen calves required sedation in the first 12 h after the operation. Tachycardia associated with bottle feeding occurred in 15 calves. Second-degree atrioventricular block was noted frequently during deep relaxation. Postmortem examination demonstrated the absence of surgical wound and distant infection, security of cannulae in all but the calf that prematurely dislodged the aortic cannula, absence of thrombus formation at cannulation sites, and presence of thromboembolism in 51% of the calves. The incidence of thromboembolic lesions was not influenced by the need for chemical restraint, by the occurrence of feeding-associated tachycardia, or by the presence of atrioventricular block. There were no thromboembolic

Left Ventricular Assist Device Design Reduces von Willebrand Factor Degradation: A Comparative Study Between the HeartMate II and the EVAHEART Left Ventricular Assist System.

PubMed

Bartoli, Carlo R; Kang, Jooeun; Zhang, David; Howard, Jessica; Acker, Michael; Atluri, Pavan; Motomura, Tadashi

2017-04-01

Supraphysiologic shear stress from continuous-flow left ventricular assist devices (LVADs) accelerates von Willebrand factor (vWF) degradation and predisposes patients to nonsurgical bleeding. It is unknown whether unique design characteristics of LVADs differentially affect vWF degradation. We tested the hypothesis that the centrifugal-flow EVAHEART (Evaheart, Houston, TX) left ventricular assist system (LVAS), which was designed to minimize shear stress (low operational revolutions per minute [rpm], larger flow gaps, low shear stress, flat H-Q curve), reduced vWF degradation versus the axial-flow HeartMate II (Thoratec, Pleasanton, CA) LVAD. Whole human blood was obtained from volunteer donors (n = 22). Blood was circulated for 12 hours in mock circulatory loops through a HeartMate II (n = 10; 11,400 rpm, 6.3 ± 0.8 L/min, 76 ± 2 mm Hg) or an EVAHEART LVAS (n = 12; 2,300 rpm, 5.7 ± 0.1 L/min, 80 ± 1 mm Hg). vWF degradation was characterized with electrophoresis and immunoblotting for large vWF multimers and 11 vWF degradation fragments. The HeartMate II eliminated large vWF multimers and significantly (p < 0.05) increased 10 of 11 vWF degradation fragments at 6 and 12 hours. The increase was approximately 2.0-fold at 6 hours and 2.2-fold at 12 hours. In contrast, the EVAHEART LVAS modestly reduced large vWF multimers and significantly increased 5 of 11 and 8 of 11 vWF degradation fragments at 6 and 12 hours, respectively. The increase was approximately 1.5-fold at 6 hours and 1.7-fold at 12 hours. The EVAHEART LVAS caused significantly less degradation (p < 0.01) than the HeartMate II of the 140 kDa vWF fragment (cleavage product of ADAMTS-13, the vWF protease). The EVAHEART LVAS caused significantly less vWF degradation than the HeartMate II in a mock circulatory loop with whole human blood. LVAD design features may minimize vWF degradation. These data may inform the design and operation of next-generation LVADs to minimize blood trauma. Copyright © 2017

Pulsatile mechanical cardiac assistance in pediatric patients with the Berlin heart ventricular assist device.

PubMed

Merkle, Frank; Boettcher, Wolfgang; Stiller, Brigitte; Hetzer, Roland

2003-06-01

Mechanical cardiac assistance for neonates, infants, children and adolescents may be accomplished with pulsatile ventricular assist devices (VAD) instead of extracorporeal membrane oxygenation or centrifugal pumps. The Berlin Heart VAD consists of extracorporeal, pneumatically driven blood pumps for pulsatile univentricular or biventricular assistance for patients of all age groups. The blood pumps are heparin-coated. The stationary driving unit (IKUS) has the required enhanced compressor performance for pediatric pump sizes. The Berlin Heart VAD was used in a total number of 424 patients from 1987 to November 2001 at our institution. In 45 pediatric patients aged 2 days-17 years the Berlin Heart VAD was applied for long-term support (1-111 days, mean 20 days). There were three patient groups: Group I: "Bridge to transplantation" with various forms of cardiomyopathy (N = 21) or chronic stages of congenital heart disease (N = 9); Group II: "Rescue" in intractable heart failure after corrective surgery for congenital disease (N = 7) or in early graft failure after heart transplantation (N = 1); and Group III: "Acute myocarditis" (N = 7) as either bridge to transplantation or bridge to recovery. Seventeen patients were transplanted after support periods of between 4 and 111 days with 12 long-term survivors, having now survived for up to 10 years. Five patients (Groups I and III) were weaned from the system with four long-term survivors. In Group II only one patient survived after successful transplantation. Prolonged circulatory support with the Berlin Heart VAD is an effective method for bridging until cardiac recovery or transplantation in the pediatric age group. Extubation, mobilization, and enteral nutrition are possible. For long-term use, the Berlin Heart VAD offers advantages over centrifugal pumps and ECMO in respect to patient mobility and safety.

Development of the NASA/Baylor VAD

NASA Technical Reports Server (NTRS)

Aber, G. S.; Akkerman, J. W.; Bozeman, R. J., Jr.; Saucler, D. R.; Bacak, J. W.; Svejkovsky, P. A.; Damm, G. A.; Mizuguchi, K.; Noon, G. P.; Nose, Y.

1994-01-01

A cooperative effort between the NASA/Johnson Space Center (JSC) and the Baylor College of Medicine (BCM) has been underway since 1988 to develop a long-term implantable Ventricular Assist Device (VAD). The VAD is intended to boost the cardiac output of patients with deteriorated cardiac function. For many of these patients, the best alternative is heart transplantation. Heart transplantation is a complex and expensive procedure and usually requires a long waiting period for a donor heart. The condition of the patient often deteriorates during this waiting period which complicates the pre and post-operative care. Because of these factors, the need for a long-term implantable VAD for use as a bridge-to-transplant device or as a permanent assist device has become the focus of much research. The need for a VAD has been estimated at 50,000 to 60,000 patients per year in the United States alone. A device which satisfies all the system performance and reliability requirements has yet to be achieved. However, the development of the NASA/Baylor VAD has progressed to a state in which commercial viability can being to be considered. The device is small, simple, efficient and reliable which meets all requirements for a totally implantable VAD.

Noninvasive arterial blood pressure waveforms in patients with continuous-flow left ventricular assist devices.

PubMed

Martina, Jerson R; Westerhof, Berend E; de Jonge, Nicolaas; van Goudoever, Jeroen; Westers, Paul; Chamuleau, Steven; van Dijk, Diederik; Rodermans, Ben F M; de Mol, Bas A J M; Lahpor, Jaap R

2014-01-01

Arterial blood pressure and echocardiography may provide useful physiological information regarding cardiac support in patients with continuous-flow left ventricular assist devices (cf-LVADs). We investigated the accuracy and characteristics of noninvasive blood pressure during cf-LVAD support. Noninvasive arterial pressure waveforms were recorded with Nexfin (BMEYE, Amsterdam, The Netherlands). First, these measurements were validated simultaneously with invasive arterial pressures in 29 intensive care unit patients. Next, the association between blood pressure responses and measures derived by echocardiography, including left ventricular end-diastolic dimensions (LVEDDs), left ventricular end-systolic dimensions (LVESDs), and left ventricular shortening fraction (LVSF) were determined during pump speed change procedures in 30 outpatients. Noninvasive arterial blood pressure waveforms by the Nexfin monitor slightly underestimated invasive measures during cf-LVAD support. Differences between noninvasive and invasive measures (mean ± SD) of systolic, diastolic, mean, and pulse pressures were -7.6 ± 5.8, -7.0 ± 5.2, -6.9 ± 5.1, and -0.6 ± 4.5 mm Hg, respectively (all <10%). These blood pressure responses did not correlate with LVEDD, LVESD, or LVSF, while LVSF correlated weakly with both pulse pressure (r = 0.24; p = 0.005) and (dP(art)/dt)max (r = 0.25; p = 0.004). The dicrotic notch in the pressure waveform was a better predictor of aortic valve opening (area under the curve [AUC] = 0.87) than pulse pressure (AUC = 0.64) and (dP(art)/dt)max (AUC = 0.61). Patients with partial support rather than full support at 9,000 rpm had a significant change in systolic pressure, pulse pressure, and (dP(art)/dt)max during ramp studies, while echocardiographic measures did not change. Blood pressure measurements by Nexfin were reliable and may thereby act as a compliment to the assessment of the cf-LVAD patient.

NASA's southeast technology transfer alliance: A cooperative technology assistance initiative

NASA Astrophysics Data System (ADS)

Craft, Harry G.; Sheehan, William; Johnson, Anne

1996-03-01

Since 1958, NASA has been charged with actively assisting in the transfer of technologies derived from the United States space program into the industrial sector of the U.S. economy. This has historically been accomplished through technology transfer offices working independently at each NASA field center. NASA recently restructured the program to provide regional coordination, maximize efficiencies, eliminate redundancies, and capitalize on each center's fundamental technology strengths. The nation is divided into six NASA technology transfer geographical regions with each region containing one or more NASA field centers and a regional technology transfer center. The southeast region includes the states of Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, and Tennessee. The NASA field centers in this region are: the Marshall Space Flight Center in Huntsville, Alabama; the Kennedy Space Center in Florida; and the Stennis Space Center in Bay St. Louis, Mississippi. The centers have teamed to focus primarily on regional industries and businesses, to provide a wide range of resources for U.S. industries, including access to unique government facilities, regional workshops, and technical problem solving. Hundreds of American businesses have benefited from this new regional initiative, as evidenced by reports of over 10,500 added or saved jobs and over 988 million worth of economic impacts as a result of their technology transfer activities.

Left ventricular assist device management in patients chronically supported for advanced heart failure.

PubMed

Cowger, Jennifer; Romano, Matthew A; Stulak, John; Pagani, Francis D; Aaronson, Keith D

2011-03-01

This review summarizes management strategies to reduce morbidity and mortality in heart failure patients supported chronically with implantable left ventricular assist devices (LVADs). As the population of patients supported with long-term LVADs has grown, patient selection, operative technique, and patient management strategies have been refined, leading to improved outcomes. This review summarizes recent findings on LVAD candidate selection, and discusses outpatient strategies to optimize device performance and heart failure management. It also reviews important device complications that warrant close outpatient monitoring. Managing patients on chronic LVAD support requires regular patient follow-up, multidisciplinary care teams, and frequent laboratory and echocardiographic surveillance to ensure optimal outcomes.

Impact of Residual Mitral Regurgitation on Right Ventricular Systolic Function After Left Ventricular Assist Device Implantation.

PubMed

Ertugay, Serkan; Kemal, Hatice S; Kahraman, Umit; Engin, Catagay; Nalbantgil, Sanem; Yagdi, Tahir; Ozbaran, Mustafa

2017-07-01

Significant mitral regurgitation (MR) is thought to decrease after left ventricular assist device (LVAD) implantation, and therefore repair of mitral valve is not indicated in current practice. However, residual moderate and severe MR leads to pulmonary artery pressure increase, thereby resulting in right ventricular (RV) dysfunction during follow-up. We examined the impact of residual MR on systolic function of the right ventricle by echocardiography after LVAD implantation. This study included 90 patients (mean age: 51.7 ± 10.9 years, 14.4% female) who underwent LVAD implantation (HeartMate II = 21, HeartWare = 69) in a single center between December 2010 and June 2014. Echocardiograms obtained at 3-6 months and over after implantation were analyzed retrospectively. RV systolic function was graded as normal, mild, moderate, and severely depressed. MR (≥moderate) was observed in 43 and 44% of patients at early and late period, respectively. Systolic function of the RV was severely depressed in 16 and 9% of all patients. Initial analysis (mean duration of support 174.3 ± 42.5 days) showed a statistically significant correlation between less MR and improved systolic function of RV (P = 0.01). Secondary echocardiographic analysis (following a mean duration of support of 435.1 ± 203 days) was also statistically significant for MR degree and RV systolic dysfunction (P = 0.008). Residual MR after LVAD implantation may cause deterioration of RV systolic function and cause right-sided heart failure symptoms. Repair of severe MR, in selected patients such as those with severe pulmonary hypertension and depressed RV, may be considered to improve the patient's clinical course during pump support. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Ventricular Recovery and Pump Explantation in Patients Supported by Left Ventricular Assist Devices: A Systematic Review.

PubMed

Phan, Kevin; Huo, Ya Ruth; Zhao, Dong Fang; Yan, Tristan D; Tchantchaleishvili, Vakhtang

2016-01-01

Several studies have reported that a portion of patients who exhibit cardiac recovery during left ventricular assist device (LVAD) support can have their device explanted with reasonable long-term survival. The aim of this systematic review is to assess the survival and cardiac function in patients with explanted LVADs from the current literature. Electronic search was performed to identify all studies in English literature assessing LVAD explantation. All identified articles were systematically assessed using the inclusion and exclusion criteria. Selected studies were subjected to quantitative assessment. From 5 electronic databases, 11 studies (213 patients) were included. Pooled mean perioperative mortality rate of those explanted was 9.2% (95% CI, 5.0-14.5%; I = 0). Pooled mean late mortality rate was 15% (95% CI, 9.0-22.1%; I = 31%). The pooled 1, 5, and 10 year survival postexplant was 91, 76, and 65.7%, respectively. Pooled postweaning freedom from heart failure (HF) recurrence reached 81.3%. Subset analysis demonstrated that patients explanted from a continuous-flow LVAD versus pulsatile LVAD had a lower rate of HF recurrence (6.6 vs. 28.3%, p = 0.03) and LVAD reimplantation (7.5 vs. 37%, p = 0.001). Before LVAD explantation, overall mean left ventricular ejection fraction (LVEF) was 49%. Weighted pooled early and late postexplantation mean LVEF was 47.3 and 41.2%, respectively. Late postexplantation LVEF was significantly higher in the continuous-flow versus pulsatile LVAD subgroup (41.5 vs. 24%, p = 0.001). This review shows encouraging safety and 10 year survival outcomes after explantation of LVADs in carefully selected patients, with rates better than expected after a heart transplant. Recovery of the native heart is the most desirable clinical outcome in patients supported with LVADs and should be actively sought.

Development and evaluation of totally implantable ventricular assist system using a vibrating flow pump and transcutaneous energy transmission system with amorphous fibers.

PubMed

Yambe, T; Hashimoto, H; Kobayashi, S; Sonobe, T; Naganuma, S; Nanka, S S; Matsuki, H; Yoshizawa, M; Tabayashi, K; Takayasu, H; Takeda, H; Nitta, S

1997-01-01

We have developed a vibrating flow pump (VFP) that can generate oscillated blood flow with a relatively high frequency (10-50 Hz) for a totally implantable ventricular assist system (VAS). To evaluate the newly developed VAS, left heart bypasses, using the VFP, were performed in chronic animal experiments. Hemodynamic parameters were recorded in a data recorder in healthy adult goats during an awake condition and analyzed in a personal computer system through an alternating-direct current converter. Basic performance of the total system with a transcutaneous energy transmission system were satisfactory. During left ventricular assistance with the VFP, Mayer wave fluctuations of hemodynamics were decreased in the power spectrum, the fractal dimensions of the hemodynamics were significantly decreased, and peripheral vascular resistance was significantly decreased. These results suggest that cardiovascular regulatory nonlinear dynamics, which mediate the hemodynamics, may be affected by left ventricular bypass with oscillated flow. The decreased power of the Mayer wave in the spectrum caused the limit cycle attractor of the hemodynamics and decreased peripheral resistance. These results suggest that this newly developed VAS is useful for the totally implantable system with unique characteristics that can control hemodynamic properties.

First use of an untethered, vented electric left ventricular assist device for long-term support.

PubMed

Frazier, O H

1994-06-01

This report describes the first long-term (505-day) application of the vented electric (VE) HeartMate left ventricular assist device (LVAD) (Thermo Cardiosystems, Inc). The device consists of an abdominally placed, battery-powered titanium blood pump that, in contrast to earlier pneumatically powered systems, allows patients untethered freedom of movement. The batteries last 5 to 8 hours and can be changed on a rotating basis indefinitely. The patient, a 33-year-old man (90 kg, blood type O) with idiopathic cardiomyopathy, experienced end-organ heart failure (New York Heart Association [NYHA] class IV) while he was awaiting heart transplantation. When his hemodynamic criteria met those outlined in the protocol, we implanted the VE-LVAD as a bridge to transplantation. The patient was supported by the device for more than 16 months. His cardiac status returned to NYHA class I, and he was eventually allowed to take day trips outside the hospital as he awaited transplantation. The VE-LVAD enabled the patient to participate in activities such as eating in restaurants, going to movies, and practicing basketball shots. Unfortunately, the patient died suddenly due to a neurological thromboembolic event that occurred on day 503 of VE-LVAD support. The VE-LVAD improved native left ventricular function by chronic unloading, and ventricular remodeling resulted in a more normal configuration anatomically, physiologically, and ultimately, histologically and pathologically.

Carotid Doppler ultrasound findings in patients with left ventricular assist devices.

PubMed

Cervini, Patrick; Park, Soon J; Shah, Dipesh K; Penev, Irina E; Lewis, Bradley D

2010-12-01

Left ventricular assist devices (LVADs) have been used to treat advanced heart failure refractory to medical management, as bridge therapy to myocardial recovery, as bridge therapy to cardiac transplantation, or as destination therapy for patients with unfavorable transplant candidacy. Neurologic complications are some of the most common and devastating complications in these patients. Preoperative carotid ultrasound is, therefore, a standard evaluation in patients at risk for cerebrovascular disease. Postoperative carotid artery Doppler sonography is performed in those patients with neurologic symptoms. It is likely, therefore, that sonographers, radiologists, and other physicians working in a center where LVADs are implanted will likely encounter a carotid artery Doppler study in this patient group. To our knowledge, the carotid Doppler findings in these patients have never been published. We review the Doppler ultrasound findings in 6 patients after LVAD insertion.

A modified Glenn shunt reduces right ventricular stroke work during left ventricular assist device therapy.

PubMed

Schiller, Petter; Vikholm, Per; Hellgren, Laila

2016-03-01

Right ventricular (RV) failure is a major cause of morbidity and mortality after left ventricular assist device (LVAD) placement and remains hard to predict. We hypothesized that partial surgical exclusion of the RV with a modified Glenn shunt during LVAD treatment would reduce RV stroke work. An LVAD was implanted in eight pigs and a modified Glenn shunt was constructed. A conductance pressure-volume catheter was placed in the right ventricle through the apex. Haemodynamic data and pressure-volume loops were obtained at the following time periods: (i) baseline, (ii) open shunt, (iii) LVAD with closed shunt and (iii) LVAD and open shunt. During LVAD therapy, the right atrial (RA) pressure increased from 9 mmHg (9-9) to 15 mmHg (12-15), P = 0.01. RV stroke volume increased from 30 ml (29-40) to 51 ml (42-53), P < 0.01. Also, RV stroke work increased to 708 mmHg ml (654-1193) from 535 mmHg ml (424-717), P = 0.04, compared with baseline. During LVAD therapy in combination with a Glenn shunt, the RA pressure decreased from 15 mmHg (12-15) to 10 mmHg (7-11) when compared with LVAD therapy only, P = 0.01. A decrease in RV stroke work from 708 mmHg ml (654-1193) to 465 mmHg ml (366-711), P = 0.04, was seen when the LVAD was combined with a shunt, not significantly different from the baseline value (535 mmHg ml). The developed pressure in the right ventricle decreased from 29 mmHg (26-32) to 21 mmHg (20-24), P < 0.01. The pressure-volume loops of the RV show a significant reduction of RV stroke work during the use of the shunt with LVAD treatment. A modified Glenn shunt reduced RV volumes, RV stroke work and RA pressure during LVAD therapy in an experimental model of heart failure in pigs. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Anesthesia for left ventricular assist device insertion: a case series and review.

PubMed

Broussard, David; Donaldson, Emilie; Falterman, Jason; Bates, Michael

2011-01-01

From October 2008 to June 2010, a total of 42 patients had the HeartMate II left ventricular assist device inserted surgically at Ochsner Medical Center in New Orleans, LA. A retrospective electronic record review was conducted on this series of patients to analyze elements of perioperative anesthetic care, including general anesthetic care, echocardiographic considerations, and blood product usage. Etomidate was used to induce anesthesia for 34 of 42 patients (81%) in this series, with an average dose of 16.5 mg (±6 mg). The average intraoperative fentanyl dose was 1,318 µg (±631 µg). On average, patients were extubated 91 hours (±72 hours) after arrival to the intensive care unit and left on day 9 (±5 days). The average left ventricular ejection fraction of the patients in this series was 13% (±5%). Sixteen patients were evaluated as having severe right-heart dysfunction preoperatively. Two of 42 patients required surgical closure of echocardiographically identified patent foramen ovale. Twelve of 42 patients underwent surgical correction of tricuspid regurgitation. On average, 3 units (±2.6 units) of fresh frozen plasma were transfused intraoperatively and 10 units postoperatively. Intraoperative red blood cell usage averaged 1.1 units (maximum, 7 units), with an average 9.3 units administered in the first 48 hours postoperatively.

Numerical Analyses for Low Reynolds Flow in a Ventricular Assist Device.

PubMed

Lopes, Guilherme; Bock, Eduardo; Gómez, Luben

2017-06-01

Scientific and technological advances in blood pump developments have been driven by their importance in cardiac patient treatments and in the expansion of life quality in assisted people. To improve and optimize the design and development, numerical tools were incorporated into the analyses of these mechanisms and have become indispensable in their advances. This study analyzes the flow behavior with low impeller Reynolds number, for which there is no consensus on the full development of turbulence in ventricular assist devices (VAD). For supporting analyses, computational numerical simulations were carried out in different scenarios with the same rotation speed. Two modeling approaches were applied: laminar flow and turbulent flow with the standard, RNG and realizable κ - ε; the standard and SST κ - ω models; and Spalart-Allmaras models. The results agree with the literature for VAD and the range for transient flows in stirred tanks with an impeller Reynolds number around 2800 for the tested scenarios. The turbulent models were compared, and it is suggested, based on the expected physical behavior, the use of κ-ε RNG, standard and SST κ-ω, and Spalart-Allmaras models to numerical analyses for low impeller Reynolds numbers according to the tested flow scenarios. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Cora rotary pump for implantable left ventricular assist device: biomaterial aspects.

PubMed

Montiès, J R; Dion, I; Havlik, P; Rouais, F; Trinkl, J; Baquey, C

1997-07-01

Our group is developing a left ventricular assist device based on the principle of the Maillard-Wankel rotative compressor: it is a rotary, not centrifugal, pump that produces a pulsatile flow. Stringent requirements have been defined for construction materials. They must be light, yet sufficiently hard and rigid, and able to be machined with high precision. The friction coefficient must be low and the wear resistance high. The materials must be chemically inert and not deformable. Also, the materials must be biocompatible, and the blood contacting surface must be hemocompatible. We assessed the materials in terms of physiochemistry, mechanics, and tribology to select the best for hemocompatibility (determined by studies of protein adsorption; platelet, leukocyte, and red cell retention; and hemolysis, among other measurements) and biocompatibility (determined by measurement of complement activation and toxicity, among other criteria). Of the materials tested, for short- and middle-term assistance, we chose titanium alloy (Ti6Al4V) and alumina ceramic (Al2O3) and for long-term and permanent use, composite materials (TiN coating on graphite). We saw that the polishing process of the substrate must be improved. For the future, the best coating material would be diamond-like carbon (DLC) or crystalline diamond coating.

Impact of tricuspid valve surgery at the time of left ventricular assist device insertion on postoperative outcomes.

PubMed

Dunlay, Shannon M; Deo, Salil V; Park, Soon J

2015-01-01

Tricuspid regurgitation (TR) is common in patients with heart failure undergoing left ventricular assist device (LVAD) implantation. Whether the TR should be surgically managed at the time of LVAD surgery is controversial. We searched SCOPUS, Web of Science, Ovid EMBASE, and Ovid MEDLINE (through May 10, 2014) for randomized controlled trials and observational studies comparing postoperative outcomes in patients treated with LVAD with concomitant tricuspid valve surgery (TVS) compared with LVAD alone. Six observational studies including 3,249 patients compared outcomes following LVAD + TVS versus LVAD. Four studies were single-center and most did not adjust for potential confounders. Addition of TVS prolonged cardiopulmonary bypass times by an average of 31 minutes (three studies, 95% CI 20-42). There was no difference in need for right ventricular assist device (six studies, HR 1.42, 95% CI 0.54-3.76), acute renal failure (four studies, HR 1.07, 95% CI 0.55-2.10), or early mortality (six studies, HR 1.28, 95% CI 0.78-2.08) in patients treated with LVAD + TVS versus LVAD alone. TVS prolongs cardiopulmonary bypass times, but available data demonstrate no significant association with early postoperative outcomes. However, differences in baseline risk of patients treated with TVS versus not limit our ability to draw conclusions.

Perioperative management of two patients with left ventricular assist devices presenting for noncardiac surgery in the prone position.

PubMed

Chacon, M Megan; Hattrup, Emily A; Shillcutt, Sasha K

2014-03-15

Ventricular assist devices (VADs) provide mechanical circulatory support for patients with advanced heart failure. Patients with VADs are presenting for noncardiac surgery with increasing frequency. Understanding anesthetic management of patients with VADs is timely and necessary for perioperative physicians. We present 2 patients supported by left VADs who required intraoperative prone positioning, and how transesophageal echocardiography and VAD variables can be used to guide management.

Toward total implantability using free-range resonant electrical energy delivery system: achieving untethered ventricular assist device operation over large distances.

PubMed

Waters, Benjamin; Sample, Alanson; Smith, Joshua; Bonde, Pramod

2011-11-01

Heart failure is a terminal disease with a very poor prognosis. Although the gold standard of treatment remains heart transplant, only a minority of patients can benefit from transplants. Another promising alternative is mechanical circulatory assistance using ventricular assist devices. The authors envision a completely implantable cardiac assist system affording tether-free mobility in an unrestricted space powered wirelessly by the innovative Free-Range Resonant Electrical Energy Device (FREE-D) system. Patients will have no power drivelines traversing the skin, and this system will allow power to be delivered over room distances and will eliminate trouble-prone wirings, bulky consoles, and replaceable batteries. Copyright © 2011 Elsevier Inc. All rights reserved.

Genetic algorithm optimization of transcutaneous energy transmission systems for implantable ventricular assist devices.

PubMed

Byron, Kelly; Bluvshtein, Vlad; Lucke, Lori

2013-01-01

Transcutaneous energy transmission systems (TETS) wirelessly transmit power through the skin. TETS is particularly desirable for ventricular assist devices (VAD), which currently require cables through the skin to power the implanted pump. Optimizing the inductive link of the TET system is a multi-parameter problem. Most current techniques to optimize the design simplify the problem by combining parameters leading to sub-optimal solutions. In this paper we present an optimization method using a genetic algorithm to handle a larger set of parameters, which leads to a more optimal design. Using this approach, we were able to increase efficiency while also reducing power variability in a prototype, compared to a traditional manual design method.

The influence of device position on the flow within the Penn State 12 cc pediatric ventricular assist device.

PubMed

Schönberger, Markus; Deutsch, Steven; Manning, Keefe B

2012-01-01

Ventricular assist devices are a commonly used heart failure therapy for adult patients as bridge-to-transplant or bridge-to-recovery tools. The application of adult ventricular assist devices in pediatric patients has led to increased thrombotic events. Therefore, we have been developing a pediatric ventricular assist device (PVAD), the Penn State 12 cc PVAD. It is designed for patients with a body weight of 5-15 kg and has a stroke volume of 12 cc. Clot formation is the major concern. It is correlated to the coagulability of blood, the blood contacting materials and the fluid dynamics within the system. The intent is for the PVAD to be a long term therapy. Therefore, the system may be oriented in different positions according to the patient's behavior. This study evaluates for the first time the impact of position on the flow patterns within the Penn State 12 cc PVAD, which may help to improve the PVAD design concerning chamber and ports geometries. The fluid dynamics are visualized by particle image velocimetry. The evaluation is based on inlet jet behavior and calculated wall shear rates. Vertical and horizontal model orientations are compared, both with a beat rate of 75, outlet pressures of 90/60 mm Hg and a flow rate of 1.3 l/min. The results show a significant change of the inlet jet behavior and the development of a rotational flow pattern. Vertically, the inlet jet is strong along the wall. It initiates a rotational flow pattern with a wandering axis of rotation. In contrast, the horizontal model orientation results show a weaker inlet jet along the wall with a nearly constant center of rotation location, which can be correlated to a higher risk of thrombotic events. In addition, high speed videography illustrates differences in the diaphragm motion during diastole. Diaphragm opening trajectories measurements determine no significant impact of the density of the blood analog fluids. Hence, the results correlate to human blood.

The Influence of Device Position on the Flow within the Penn State 12 cc Pediatric Ventricular Assist Device

PubMed Central

Schönberger, Markus; Deutsch, Steven; Manning, Keefe B.

2012-01-01

Ventricular assist devices are a commonly used heart failure therapy for adult patients as bridge-to-transplant or bridge-to-recovery tool. The application of adult ventricular assist devices in pediatric patients has led to increased thrombotic events. Therefore, we have been developing a pediatric ventricular assist device, the Penn State 12 cc PVAD. It is designed for patients with a body weight of 5 to 15 kg and has a stroke volume of 12 cc. Clot formation is the major concern. It is correlated to the coagulability of blood, the blood contacting materials and the fluid dynamics within the system. The intent is for the PVAD to be a long term therapy. Therefore, the system may be oriented in different positions according to the patient’s behavior. This study evaluates for the first time the impact of position on the flow patterns within the Penn State 12 cc PVAD, which may help to improve the PVAD design concerning chamber and ports geometries. The fluid dynamics are visualized by particle image velocimetry. The evaluation is based on inlet jet behavior and calculated wall shear rates. Vertical and horizontal model orientations are compared, both with a beat rate of 75, outlet pressures of 90/60 mmHg and a flow rate of 1.3 l/min. The results show a significant change of the inlet jet behavior and the development of a rotational flow pattern. Vertically, the inlet jet is strong along the wall. It initiates a rotational flow pattern with a wandering axis of rotation. In contrast, the horizontal model orientation results show a weaker inlet jet along the wall with a nearly constant center of rotation location, which can be correlated to a higher risk of thrombotic events. In addition high speed videography illustrates differences in the diaphragm motion during diastole. Diaphragm opening trajectories measurements determine no significant impact of the density of the blood analog fluids. Hence, the results correlate to human blood. PMID:22929894

Experimental Assessment of the Hydraulics of a Miniature Axial-Flow Left Ventricular Assist Device

NASA Astrophysics Data System (ADS)

Smith, P. Alex; Cohn, William; Metcalfe, Ralph

2017-11-01

A minimally invasive partial-support left ventricular assist device (LVAD) has been proposed with a flow path from the left atrium to the arterial system to reduce left ventricular stroke work. In LVAD design, peak and average efficiency must be balanced over the operating range to reduce blood trauma. Axial flow pumps have many geometric parameters. Until recently, testing all these parameters was impractical, but modern 3D printing technology enables multi-parameter studies. Following theoretical design, experimental hydraulic evaluation in steady state conditions examines pressure, flow, pressure-flow gradient, efficiency, torque, and axial force as output parameters. Preliminary results suggest that impeller blades and stator vanes with higher inlet angles than recommended by mean line theory (MLT) produce flatter gradients and broader efficiency curves, increasing compatibility with heart physiology. These blades also produce less axial force, which reduces bearing load. However, they require slightly higher torque, which is more demanding of the motor. MLT is a low order, empirical model developed on large pumps. It does not account for the significant viscous losses in small pumps like LVADs. This emphasizes the importance of experimental testing for hydraulic design. Roderick D MacDonald Research Fund.

Successful Implantation of a Left Ventricular Assist Device After Treatment With the Paracor HeartNet.

PubMed

Schweiger, Martin; Stepanenko, Alexander; Potapov, Evgenji; Drews, Thorsten; Hetzer, Roland; Krabatsch, Thomas

2010-01-01

The Paracor HeartNet, a ventricular constraint device for the treatment of heart failure (HF), is implanted through a left lateral thoracotomy. It envelopes the heart like a mesh "bag." This method of application raises the question of whether adhesions with the pericardium allow the safe implantation of a left ventricular assist device (LVAD) if HF worsens. A male patient who had undergone implantation of the Paracor HeartNet 42 months earlier presented with advanced HF for cardiac transplantation. The patient's condition deteriorated, and because no suitable organ for transplantation was available, implantation of an LVAD became necessary. Surgery was performed via a median sternotomy without complications. No severe adhesions were found. This is the first report on "how to do" LVAD implantation after Paracor HeartNet implantation with images and information about cutting the constraint. Because the Paracor HeartNet is "wrapped" around the heart, concerns persist that severe adhesions with the pericardium might occur. In this case, LVAD implantation after therapy with the Paracor HeartNet was without complications, and the expected massive adhesions were absent.

Pump Thrombosis following HeartMate II Left Ventricular Assist Device Implantation in a Patient with Aspirin and Plavix Resistance.

PubMed

Ghodsizad, Ali; Badiye, A; Zeriouh, M; Pae, W; Koerner, M M; Loebe, M

2016-12-14

Despite advances in pump technology, thromboembolic events and pump thrombosis are potentially life-threatening complications in patients with continuous flow ventricular assist devices. Here we describe a patient with pump thrombosis following LVAD HeartMate II implantation presenting with Aspirin and Plavix resistance and signs of acute hemolysis as manifested by high LDH, changing pump power, pulse index and reduced pump flows.

Numerical and In Vitro Experimental Investigation of the Hemolytic Performance at the Off-Design Point of an Axial Ventricular Assist Pump.

PubMed

Liu, Guang-Mao; Jin, Dong-Hai; Jiang, Xi-Hang; Zhou, Jian-Ye; Zhang, Yan; Chen, Hai-Bo; Hu, Sheng-Shou; Gui, Xing-Min

The ventricular assist pumps do not always function at the design point; instead, these pumps may operate at unfavorable off-design points. For example, the axial ventricular assist pump FW-2, in which the design point is 5 L/min flow rate against 100 mm Hg pressure increase at 8,000 rpm, sometimes works at off-design flow rates of 1 to 4 L/min. The hemolytic performance of the FW-2 at both the design point and at off-design points was estimated numerically and tested in vitro. Flow characteristics in the pump were numerically simulated and analyzed with special attention paid to the scalar sheer stress and exposure time. An in vitro hemolysis test was conducted to verify the numerical results. The simulation results showed that the scalar shear stress in the rotor region at the 1 L/min off-design point was 70% greater than at the 5 L/min design point. The hemolysis index at the 1 L/min off-design point was 3.6 times greater than at the 5 L/min design point. The in vitro results showed that the normalized index of hemolysis increased from 0.017 g/100 L at the 5 L/min design point to 0.162 g/100 L at the 1 L/min off-design point. The hemolysis comparison between the different blood pump flow rates will be helpful for future pump design point selection and will guide the usage of ventricular assist pumps. The hemolytic performance of the blood pump at the working point in the clinic should receive more focus.

Right ventricular longitudinal strain and right ventricular stroke work index in patients with severe heart failure: left ventricular assist device suitability for transplant candidates.

PubMed

Cameli, M; Bernazzali, S; Lisi, M; Tsioulpas, C; Croccia, M G; Lisi, G; Maccherini, M; Mondillo, S

2012-09-01

Right ventricular (RV) systolic function has a critical role in determining the clinical outcome and the success of using left ventricular assist devices in patients with refractory heart failure. RV deformation analysis by speckle tracking echocardiography (STE) has recently allowed the analysis of RV longitudinal function. Using cardiac catheterization as the reference standard, this study aimed to explore the correlation between RV longitudinal function by STE and RV stroke work index (RVSWI) among patients referred for cardiac transplantation. Right heart catheterization and transthoracic echo-Doppler were simultaneously performed in 47 patients referred for cardiac transplant assessment due to refractory heart failure (ejection fraction 25.1 ± 4.5%). Thermodilution RV stroke volume and invasive pulmonary pressures were used to obtain RVSWI. RV longitudinal strain (RVLS) by STE was assessed averaging RV free-wall segments (free-wall RVLS). We also calculated. Tricuspid S' and tricuspid annular plane systolic excursion (TAPSE). No significant correlation was observed for TAPSE on tricuspid S' with RV stroke volume (r = 0.14 and r = 0.06, respectively). A close negative correlation between free-wall RVLS and RVSWI was found (r = -0.82; P < .0001). Furthermore, free-wall RVLS showed the highest diagnostic accuracy (area under the curve of 0.90) with good sensitivity and specificity of 95% and 91%, respectively, to predict depressed RVSWI using a cutoff value less than -11.8%. Among patients referred for heart transplantation, TAPSE and tricuspid S' did not correlate with invasively obtained RVSWI. RV longitudinal deformation analysis by STE correlated with RVSWI, providing a better estimate of RV systolic performance. Copyright © 2012 Elsevier Inc. All rights reserved.

Magnetic Launch Assist: NASA's Vision for the Future

NASA Technical Reports Server (NTRS)

Jacobs, William A.; Montenegro, Justino (Technical Monitor)

2000-01-01

With the ever-increasing cost of getting to space and the need for safe, reliable, and inexpensive ways to access space. The National Aeronautics and Space Administration (NASA) is taking a look at technologies that will get us there. One of these technologies is Magnetic Launch Assist (MagLev). This is the concept of using both magnetic levitation and magnetic propulsion to provide an initial velocity by using electrical power from ground sources. The use of ground generated electricity can significantly reduce operational costs over the consumables necessary to attain the same velocity. The technologies to accomplish this are both old and new. The concept of MagLev has been around for a long time and several MagLev Trains have been developed. Where NASA's MagLev diverges from the traditional train is in the immense amount of power required to propel this vehicle to 183 meters per second in less than 10 seconds. New technologies or the upgrade of existing technologies will need to be investigated in the areas of energy storage and power switching. An added difficulty is the separation of a very large mass (the space vehicle) from the track and the aerodynamics of that vehicle while on the track. These are of great concern and require considerable study and testing. NASA's plan is to mature these technologies in the next 25 years to achieve our goal of launching a full sized space vehicle for under $300 a kilogram.

Animal Model Development for the Penn State Pediatric Ventricular Assist Device

PubMed Central

Carney, Elizabeth L.; Clark, J. Brian; Myers, John L.; Peterson, Rebecca; Wilson, Ronald P.; Weiss, William J.

2009-01-01

In March 2004, the National Heart, Lung, and Blood Institute (NHLBI) awarded five contracts to develop devices providing circulatory support for infants and small children with congenital and acquired cardiac disease. Since 2004, the team at Penn State College of Medicine has developed a pneumatically-actuated ventricular assist device (VAD) with mechanical tilting disk valves. To date, hemodynamic performance, thrombogenesis, and hemolysis have been chronically evaluated in 16 animals, including 4 pygmy goats and 12 sheep. Major complications, mainly respiratory failure, have been encountered and resolved by a multi-disciplinary team. Multi-modal analgesia, appropriate antibiotic therapy, and attentive animal care have contributed to successful outcomes. Time after implant has ranged from 0–40 days. Most recently, a sheep implanted with Version 3 Infant VAD was electively terminated at 35 days post-implant, with no major adverse events. This report describes a successful in vivo model for evaluating a pediatric VAD. PMID:19849686

Simulation of Ventricular, Cavo-Pulmonary, and Biventricular Ventricular Assist Devices in Failing Fontan.

PubMed

Di Molfetta, Arianna; Amodeo, Antonio; Fresiello, Libera; Trivella, Maria Giovanna; Iacobelli, Roberta; Pilati, Mara; Ferrari, Gianfranco

2015-07-01

Considering the lack of donors, ventricular assist devices (VADs) could be an alternative to heart transplantation for failing Fontan patients, in spite of the lack of experience and the complex anatomy and physiopathology of these patients. Considering the high number of variables that play an important role such as type of Fontan failure, type of VAD connection, and setting (right VAD [RVAD], left VAD [LVAD], or biventricular VAD [BIVAD]), a numerical model could be useful to support clinical decisions. The aim of this article is to develop and test a lumped parameter model of the cardiovascular system simulating and comparing the VAD effects on failing Fontan. Hemodynamic and echocardiographic data of 10 Fontan patients were used to simulate the baseline patients' condition using a dedicated lumped parameter model. Starting from the simulated baseline and for each patient, a systolic dysfunction, a diastolic dysfunction, and an increment of the pulmonary vascular resistance were simulated. Then, for each patient and for each pathology, the RVAD, LVAD, and BIVAD implantations were simulated. The model can reproduce patients' baseline well. In the case of systolic dysfunction, the LVAD unloads the single ventricle and increases the cardiac output (CO) (35%) and the arterial systemic pressure (Pas) (25%). With RVAD, a decrement of inferior vena cava pressure (Pvci) (39%) was observed with 34% increment of CO, but an increment of the single ventricle external work (SVEW). With the BIVAD, an increment of Pas (29%) and CO (37%) was observed. In the case of diastolic dysfunction, the LVAD increases CO (42%) and the RVAD decreases the Pvci, while both increase the SVEW. In the case of pulmonary vascular resistance increment, the highest CO (50%) and Pas (28%) increment is obtained with an RVAD with the highest decrement of Pvci (53%) and an increment of the SVEW but with the lowest VAD power consumption. The use of numerical models could be helpful in this innovative

Long-term in vivo left ventricular assist device study with a titanium centrifugal pump.

PubMed

Ohtsuka, G; Nakata, K; Yoshikawa, M; Mueller, J; Takano, T; Yamane, S; Gronau, N; Glueck, J; Takami, Y; Sueoka, A; Letsou, G; Schima, H; Schmallegger, H; Wolner, E; Koyanagi, H; Fujisawa, A; Baldwin, J C; Nosé, Y

1998-01-01

A totally implantable centrifugal artificial heart has been developed. The plastic prototype, Gyro PI 601, passed 2 day hemodynamic tests as a functional total artificial heart, 2 week screening tests for antithrombogenicity, and 1 month system feasibility. Based on these results, a metallic prototype, Gyro PI 702, was subjected to in vivo left ventricular assist device (LVAD) studies. The pump system employed the Gyro PI 702, which has the same inner dimensions and the same characteristics as the Gyro PI 601, including an eccentric inlet port, a double pivot bearing system, and a magnet coupling system. The PI 702 is driven with the Vienna DC brushless motor actuator. For the in vivo LVAD study, the pump actuator package was implanted in the preperitoneal space in two calves, from the left ventricular apex to the descending aorta. Case 1 achieved greater than 9 month survival without any complications, at an average flow rate of 6.6 L/min with 10.2 W input power. Case 2 was killed early due to the excessive growth of the calf, which caused functional obstruction of the inlet port. There was no blood clot inside the pump. During these periods, neither case exhibited any physiologic abnormalities. The PI 702 pump gives excellent results as a long-term implantable LVAD.

Simulation based efficiency prediction of a Brushless DC drive applied in ventricular assist devices.

PubMed

Pohlmann, André; Hameyer, Kay

2012-01-01

Ventricular Assist Devices (VADs) are mechanical blood pumps that support the human heart in order to maintain a sufficient perfusion of the human body and its organs. During VAD operation blood damage caused by hemolysis, thrombogenecity and denaturation has to be avoided. One key parameter causing the blood's denaturation is its temperature which must not exceed 42 °C. As a temperature rise can be directly linked to the losses occuring in the drive system, this paper introduces an efficiency prediction chain for Brushless DC (BLDC) drives which are applied in various VAD systems. The presented chain is applied to various core materials and operation ranges, providing a general overview on the loss dependencies.

Cardiac transplantation after bridged therapy with continuous flow left ventricular assist devices.

PubMed

Deo, Salil V; Sung, Kiick; Daly, Richard C; Shah, Ishan K; Altarabsheh, Salah E; Stulak, John M; Joyce, Lyle D; Boilson, Barry A; Kushwaha, Sudhir S; Park, Soon J

2014-03-01

Cardiac transplantation is an effective surgical therapy for end-stage heart failure. Patients (pts) may need to be bridged with a continuous flow left ventricular assist device (CF-LVAD) while on the transplant list as logistic factors like organ availability are unknown. Cardiac transplantation post-LVAD can be a surgically challenging procedure and outcome in these pts is perceived to be poorer based on experience with earlier generation pulsatile flow pumps. Data from a single institution comparing these pts with those undergoing direct transplantation in the present era of continuous flow device therapy are limited. Evaluate results of cardiac transplantation in pts bridged with a CF-LVAD (BTx) and compare outcomes with pts undergoing direct transplantation (Tx) in a single institution. From June 2007 till January 2012, 106 pts underwent cardiac transplantation. Among these, 37 (35%) pts (51±11 years; 85% male) were bridged with a CF-LVAD (BTx), while 70 (65%) comprised the Tx group (53±12 years; 72% males). The median duration of LVAD support was 227 (153,327) days. During the period of LVAD support, 10/37 (27%) pts were upgraded to status 1A and all were successfully transplanted. Median hospital stay in the BTx (14 days) was slightly longer than the Tx group (12 days) but not statistically significant (p=0.21). In-hospital mortality in the BTx (5%) and Tx (1%) were comparable (p=0.25). Estimated late survival in the BTx cohort was 94±7, 90±10 and 83±16% at the end of one, two and three years, respectively which was comparable to 97±4%, 93±6% and 89±9% for the Tx group (p=0.50). Cardiac transplantation after LVAD implant can be performed with excellent results. Patients can be supported on the left ventricular assist device even for periods close to a year with good outcome after cardiac transplantation. Copyright © 2013 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand

First pediatric transatlantic air ambulance transportation on a Berlin Heart EXCOR left ventricular assist device as a bridge to transplantation.

PubMed

Tissot, Cecile; Buchholz, Holger; Mitchell, Max B; da Cruz, Eduardo; Miyamoto, Shelley D; Pietra, Bill A; Charpentier, Arnaud; Ghez, Olivier

2010-03-01

Mechanical circulatory devices are indicated in patients with refractory cardiac failure as a bridge to recovery or to transplantation. Whenever required, transportation while on mechanical support is a challenge and still limited by technical restrictions or distance. We report the first pediatric case of transatlantic air transportation on a Berlin Heart EXCOR ventricular assist device (Berlin Heart, Berlin, Germany) of a 13-yr-old American female who presented in cardiogenic shock with severe systolic dysfunction while vacationing in France. Rapid hemodynamic deterioration occurred despite maximal medical treatment, and she was supported initially with extracorporeal membrane oxygenation converted to a Berlin Heart EXCOR left ventricular assist device. Long-distance air transportation of the patient was accomplished 3 wks after implantation from Marseille, France, to Denver, Colorado. No adverse hemodynamic effects were encountered during the 13.5-hr flight (8770 km). The patient did not recover sufficient cardiac function and underwent successful orthotopic heart transplantation 3 months after the initial event. Our experience suggests that long-distance air transportation of pediatric patients using the Berlin Heart EXCOR mobile unit as a bridge to recovery or transplantation is feasible and appears safe.

iPhone in the Management of the Berlin Heart EXCOR Ventricular Assist Device.

PubMed

Badheka, Aditya; Allareddy, Veerajalandhar

Berlin Heart Inc. EXCOR is an extracorporeal pneumatically pulsatile ventricular assist device approved for use in pediatric age group since 2011 in the United States. It is a well-established life-saving therapy for the bridge to heart transplant or to provide circulatory support in a transplanted patient. The most commonly reported problem was "membrane defect" in a postmarketing major device reporting. In general, the filling and emptying of the pump can be easily visualized, but the interobserver variability exist. In this first novel report, we used the iPhone slow motion video to quantify and compare the differences in filling and emptying that positively impacted the management of the Berlin Heart. This is an initial exploratory concept that will need further studies to validate this bedside tool.

In vivo biocompatibility evaluation of a new resilient, hard-carbon, thin-film coating for ventricular assist devices.

PubMed

Takaseya, Tohru; Fumoto, Hideyuki; Shiose, Akira; Arakawa, Yoko; Rao, Santosh; Horvath, David J; Massiello, Alex L; Mielke, Nicole; Chen, Ji-Feng; Zhou, Qun; Dessoffy, Raymond; Kramer, Larry; Benefit, Stephen; Golding, Leonard A R; Fukamachi, Kiyotaka

2010-12-01

The purpose of this study was to evaluate in vivo the biocompatibility of BioMedFlex (BMF), a new resilient, hard-carbon, thin-film coating, as a blood journal bearing material in Cleveland Heart's (Charlotte, NC, USA) continuous-flow right and left ventricular assist devices (RVADs and LVADs). BMF was applied to RVAD rotating assemblies or both rotating and stator assemblies in three chronic bovine studies. In one case, an LVAD with a BMF-coated stator was also implanted. Cases 1 and 3 were electively terminated at 18 and 29 days, respectively, with average measured pump flows of 4.9 L/min (RVAD) in Case 1 and 5.7 L/min (RVAD) plus 5.7 L/min (LVAD) in Case 3. Case 2 was terminated prematurely after 9 days because of sepsis. The sepsis, combined with running the pump at minimum speed (2000 rpm), presented a worst-case biocompatibility challenge. Postexplant evaluation of the blood-contacting journal bearing surfaces showed no biologic deposition in any of the four pumps. Thrombus inside the RVAD inlet cannula in Case 3 is believed to be the origin of a nonadherent thrombus wrapped around one of the primary impeller blades. In conclusion, we demonstrated that BMF coatings can provide good biocompatibility in the journal bearing for ventricular assist devices. © 2010, Copyright the Authors. Artificial Organs © 2010, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

The DeBakey classification exactly reflects late outcome and re-intervention probability in acute aortic dissection with a slightly modified type II definition.

PubMed

Tsagakis, Konstantinos; Tossios, Paschalis; Kamler, Markus; Benedik, Jaroslav; Natour, Dorgam; Eggebrecht, Holger; Piotrowski, Jarowit; Jakob, Heinz

2011-11-01

The DeBakey classification was used to discriminate the extent of acute aortic dissection (AD) and was correlated to long-term outcome and re-intervention rate. A slight modification of type II subgroup definition was applied by incorporating the aortic arch, when full resectability of the dissection process was given. Between January 2001 and March 2010, 118 patients (64% male, mean age 59 years) underwent surgery for acute AD. As many as 74 were operated on for type I and 44 for type II AD. Complete resection of all entry sites was performed, including antegrade stent grafting for proximal descending lesions. Patients were comparable with respect to demographics and preoperative hemodynamic status. They underwent isolated ascending replacement, hemiarch, or total arch replacement in 7%, 26%, and 67% in type I, versus 27%, 37%, and 36% in type II, respectively. Additional descending stent grafting was performed in 33/74 (45%) type I patients. In-hospital mortality was 14%, 16% (12/74) in type I versus 9% (4/44, type II), p=0.405. After 5 years, the estimated survival rate was 63% in type I versus 80% in type II, p=0.135. In type II, no distal aortic re-intervention was required. In type I, the freedom of distal re-interventions was 82% in patients with additional stent grafting versus 53% in patients without, p=0.022. The slightly modified DeBakey classification exactly reflects late outcome and aortic re-intervention probability. Thus, in type II patients, the aorta seems to be healed without any probability of later re-operation or re-intervention. Copyright © 2011 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.

Cangrelor use prior to left ventricular assist device surgery: a case series.

PubMed

Washam, Jeffrey B; Yerokun, Babatunde; Patel, Chetan B; Welsby, Ian J; Milano, Carmelo A; DeVore, Adam D

2018-06-02

Bleeding frequently occurs in patients undergoing placement of a left ventricular assist device (LVAD). Clinical factors that have been identified as contributing to peri-procedural bleeding include LVAD implantation after an acute myocardial infarction and preoperative use of antiplatelet agents. In this report, we describe the use of cangrelor for preoperative antiplatelet bridging to LVAD in five post myocardial infarction patients with cardiogenic shock that had recently undergone percutaneous coronary intervention. During the cangrelor bridging period, no cases of thrombotic or major bleeding events occurred. During the first week following LVAD implantation, two patients experienced a major bleeding (each case required chest exploration for suspected hemorrhage). To our knowledge, this is the first series describing cangrelor use for antiplatelet bridging in patients undergoing LVAD implantation. While this series suggest cangrelor could possibly be a safe and effective antiplatelet bridging strategy, further research is needed to identify the optimal antithrombotic strategy in cardiogenic shock patients undergoing LVAD implantation who have recently undergoing percutaneous coronary intervention.

Usefulness of Palliative Care to Complement the Management of Patients on Left Ventricular Assist Devices

PubMed Central

Luo, Nancy; Rogers, Joseph G.; Dodson, Gwen C.; Patel, Chetan B.; Galanos, Anthony N.; Milano, Carmelo A.; O’Connor, Christopher M.; Mentz, Robert J.

2016-01-01

Within the last decade, advancements in left ventricular assist device (LVAD) therapy have allowed end-stage heart failure patients to live longer and with better quality of life. Like other life-saving interventions, however, there remains the risk of complications including infections, bleeding episodes, and stroke. The candidate for LVAD therapy faces complex challenges going forward, both physical and psychological, many of which may benefit from the application of palliative care principles by trained specialists. Despite these advantages, palliative care remains underused in many advanced heart failure programs. Here, we describe the benefits of palliative care, barriers to use within heart failure, and specific applications to the integrated care of patients on mechanical circulatory support. PMID:27474339

Magnetic design for the PediaFlow ventricular assist device.

PubMed

Noh, Myounggyu D; Antaki, James F; Ricci, Michael; Gardiner, Jeff; Paden, Dave; Wu, Jingchun; Prem, Ed; Borovetz, Harvey; Paden, Bradley E

2008-02-01

This article describes a design process for a new pediatric ventricular assist device, the PediaFlow. The pump is embodied in a magnetically levitated turbodynamic design that was developed explicitly based on the requirements for chronic support of infants and small children. The procedure entailed the consideration of multiple pump topologies, from which an axial mixed-flow configuration was chosen for further development. The magnetic design includes permanent-magnet (PM) passive bearings for radial support of the rotor, an actively controlled thrust actuator for axial support, and a brushless direct current (DC) motor for rotation. These components are closely coupled both geometrically and magnetically, and were therefore optimized in parallel, using electromagnetic, rotordynamic models and fluid models, and in consideration of hydrodynamic requirements. Multiple design objectives were considered, including efficiency, size, and margin between critical speeds to operating speed. The former depends upon the radial and yaw stiffnesses of the PM bearings. Analytical expressions for the stiffnesses were derived and verified through finite element analysis (FEA). A toroidally wound motor was designed for high efficiency and minimal additional negative radial stiffness. The design process relies heavily on optimization at the component level and system level. The results of this preliminary design optimization yielded a pump design with an overall stability margin of 15%, based on a pressure rise of 100 mm Hg at 0.5 lpm running at 16,000 rpm.

Newly developed ventricular assist device with linear oscillatory actuator.

PubMed

Fukunaga, Kazuyoshi; Funakubo, Akio; Fukui, Yasuhiro

2003-01-01

The goal of this study was to develop a new direct electromagnetic left ventricular assist device (DEM-LVAD) with a linear oscillatory actuator (LOA). The DEM-LVAD is a pulsatile pump with a pusher plate. The pusher plate is driven directly by the mover of the LOA. The LOA provides reciprocating motion without using any movement converter such as a roller screw or a hydraulic system. It consists of a stator with a single winding excitation coil and a mover with two permanent magnets. The simple structure of the LOA is based on fewer parts to bring about high reliability and smaller size. The mover moves back and forth when forward and backward electric current is supplied to the excitation coil. The pump housings have been designed using three-dimensional computer aided design software and fabricated with the aid of computer aided manufacturing technology. Monostrut valves (Bjork-Shiley #21) were used for the prototype. The DEM-LVAD dimension is 96 mm in diameter and 50 mm thick with a mass of 0.62 kg and a volume of 280 ml. An in vitro test (afterload 100 mm Hg; preload 10 mm Hg; input power 10 W) demonstrated more than 6 L/minute maximum output and 15% maximum efficiency at 130 beats per minute (bpm). Dynamic stroke volume ranged between 40 and 60 ml. The feasibility of the DEM-LVAD was confirmed.

Interhospital air transport of a blind patient on extracorporeal life support with consecutive and successful left ventricular assist device implantation.

PubMed

Bauer, Adrian; Schaarschmidt, Jan; Grosse, F Oliver; Al Alam, Nidal; Hausmann, Harald; Krämer, Klaus; Strüber, Martin; Mohr, Friedrich W

2014-06-01

The use of extracorporeal life support systems (ECLS) in patients with postcardiotomy low cardiac output syndrome (LCO) as a bridge to recovery and bridge to implantation of ventricular assist device (VAD) is common nowadays. A 59-year-old patient with acute myocardial infarction received a percutaneous transluminal angioplasty and stenting of the circumflex artery. During catheterization of the left coronary artery (LAD), the patient showed ventricular fibrillation and required defibrillation and cardiopulmonary resuscitation. After implantation of an intra-aortic balloon pump, the patient immediately was transmitted to the operating room. He received emergency coronary artery bypass grafting in a beating heart technique using pump-assisted minimal extracorporeal circulation circuit (MECC). Two bypass grafts were performed to the LAD and the right posterior descending artery. Despite initial successful weaning off cardiopulmonary bypass with high-dose inotropic support, the patient presented postcardiotomy LCO and an ECLS was implanted. The primary setup of the heparin-coated MECC system was modified and used postoperatively. As a result of the absence of an in-house VAD program, the patient was switched to a transportable ECLS the next day and was transferred by helicopter to the nearest VAD center where the patient received a successful insertion of a left VAD 3 days later.

Clinical manifestations and management of left ventricular assist device-associated infections.

PubMed

Nienaber, Juhsien Jodi C; Kusne, Shimon; Riaz, Talha; Walker, Randall C; Baddour, Larry M; Wright, Alan J; Park, Soon J; Vikram, Holenarasipur R; Keating, Michael R; Arabia, Francisco A; Lahr, Brian D; Sohail, M Rizwan

2013-11-01

Infection is a serious complication of left ventricular assist device (LVAD) therapy. Published data regarding LVAD-associated infections (LVADIs) are limited by single-center experiences and use of nonstandardized definitions. We retrospectively reviewed 247 patients who underwent continuous-flow LVAD implantation from January 2005 to December 2011 at Mayo Clinic campuses in Minnesota, Arizona, and Florida. LVADIs were defined using the International Society for Heart and Lung Transplantation criteria. We identified 101 episodes of LVADI in 78 patients (32%) from this cohort. Mean age (± standard deviation [SD]) was 57±15 years. The majority (94%) underwent Heartmate II implantation, with 62% LVADs placed as destination therapy. The most common type of LVADIs were driveline infections (47%), followed by bloodstream infections (24% VAD related, and 22% non-VAD related). The most common causative pathogens included gram-positive cocci (45%), predominantly staphylococci, and nosocomial gram-negative bacilli (27%). Almost half (42%) of the patients were managed by chronic suppressive antimicrobial therapy. While 14% of the patients had intraoperative debridement, only 3 underwent complete LVAD removal. The average duration (±SD) of LVAD support was 1.5±1.0 years. At year 2 of follow-up, the cumulative incidence of all-cause mortality was estimated to be 43%. Clinical manifestations of LVADI vary on the basis of the type of infection and the causative pathogen. Mortality remained high despite combined medical and surgical intervention and chronic suppressive antimicrobial therapy. Based on clinical experiences, a management algorithm for LVADI is proposed to assist in the decision-making process.

Impella™ Left Ventricular Assist Device for Acute Peripartum Cardiomyopathy After Cesarean Delivery.

PubMed

Padilla, Cesar; Hernandez Conte, Antonio; Ramzy, Danny; Sanchez, Michael; Zhao, Manxu; Park, Donald; Lubin, Lorraine

2016-07-01

Peripartum cardiomyopathy is a rare form of heart failure with significant perioperative implications. In this case report, we describe a 34-year-old gravida 5, parity 3, patient who was admitted for an elective cesarean delivery. During the delivery, the patient developed sudden cardiac arrest and was emergently intubated in the operating room. An emergent transesophageal echocardiogram revealed a left ventricular ejection fraction of 10% with global biventricular hypokinesis. Urgent multidisciplinary consultations led to the rapid implementation of the Impella™ 2.5 for ventricular support. The patient recovered ventricular function within 4 days and recovered to baseline function.

Experience With a Long-term Pulsatile Ventricular Assist Device as a Bridge to Heart Transplant in Adults.

PubMed

Gómez Bueno, Manuel; Segovia Cubero, Javier; Serrano Fiz, Santiago; Ugarte Basterrechea, Juan; Hernández Pérez, Francisco José; Goirigolzarri Artaza, Josebe; Castedo Mejuto, Evaristo; Burgos Lázaro, Raúl; García Montero, Carlos; Moñivas Palomero, Vanessa; Mingo Santos, Susana; González Román, Ana Isabel; Álvarez Avelló, José Manuel; Vidal Fernández, Mercedes; Forteza Gil, Alberto; Alonso-Pulpón, Luis

2017-09-01

Most long-term ventricular assist devices (VADs) that are currently implanted are intracorporeal continuous-flow devices. Their main limitations include their high cost and inability to provide biventricular support. The aim of this study was to describe the results of using paracorporeal pulsatile-flow VADs as a bridge to transplant (BTT) in adult patients. Retrospective analysis of the characteristics, complications, and outcomes of a single-center case series of consecutive patients treated with the EXCOR VAD as BTT between 2009 and 2015. During the study period, 25 VADs were implanted, 6 of them biventricular. Ventricular assist devices were indicated directly as a BTT in 12 patients and as a bridge to decision in 13 due to the presence of potentially reversible contraindications or chance of heart function recovery. Twenty patients (80%) were successfully bridged to heart transplant after a median of 112 days (range, 8-239). The main complications included infectious (52% of patients), neurological events (32%, half of them fatal), bleeding (28%), and VAD malfunction requiring component replacement (28%). Eighty percent of patients with the EXCOR VAD as BTT achieved the goal after an average of almost 4 months of support. The most frequent complications were infectious, and the most severe were neurological. In our enivonment, the use of these pulsatile-flow VAD as BTT is a feasible strategy that obtains similar outcomes to those of intracorporeal continuous-flow devices. Copyright © 2016 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

High pulmonary vascular resistance in addition to low right ventricular stroke work index effectively predicts biventricular assist device requirement.

PubMed

Imamura, Teruhiko; Kinugawa, Koichiro; Kinoshita, Osamu; Nawata, Kan; Ono, Minoru

2016-03-01

Although the right ventricular stroke work index (RVSWI) is a good index for RV function, a low RVSWI is not necessarily an indicator for the need for a right ventricular assist device at the time of left VAD implantation. We here aimed to determine a more precise indicator for the need for a biventricular assist device (BiVAD). In total, 116 patients (mean age, 38 ± 14 years), who underwent hemodynamic assessments preoperatively including 12 BiVAD patients, and had been followed at our institute from 2003 to 2015, were included. Multivariate logistic regression analysis indicated that RVSWI and pulmonary vascular resistance (PVR) were independent predictors of BiVAD requirement (P < 0.05 for both). In addition, all patients were classified into 4 groups: (1) normal (RVSWI > 5 g/m, PVR < 3.7 WU), (2) pulmonary hypertension (RVSWI > 5, PVR > 3.7), (3) RV failure (RVSWI < 5, PVR < 3.7), and (4) both pulmonary hypertension and RV failure (RVSWI < 5, PVR > 3.7), and examined. Most of the patients in Group 4 (75 %), with acutely depressed hemodynamics and inflammatory responses in the myocardium, required BiVAD. Overall, patients with BiVAD had a worse survival rate as compared with those with LVAD alone. In conclusion, high PVR in addition to low RVSWI effectively predicts BiVAD requirement.

Risk Stratification of Patients With Current Generation Continuous-Flow Left Ventricular Assist Devices Being Bridged to Heart Transplantation.

PubMed

Guha, Ashrith; Nguyen, Duc; Cruz-Solbes, Ana S; Amione-Guerra, Javier; Schutt, Robert C; Bhimaraj, Arvind; Trachtenberg, Barry H; Park, Myung H; Graviss, Edward A; Gaber, Osama; Suarez, Erik; Montane, Eva; Torre-Amione, Guillermo; Estep, Jerry D

Patients bridged to transplant (BTT) with continuous-flow left ventricular assist devices (CF-LVADs) have increased in the past decade. Decision support tools for these patients are limited. We developed a risk score to estimate prognosis and guide decision-making. We included heart transplant recipients bridged with CF-LVADs from the United Network for Organ Sharing (UNOS) database and divided them into development (2,522 patients) and validation cohorts (1,681 patients). Univariate and multivariate Cox proportional hazards models were performed. Variables that independently predicted outcomes (age, African American race, recipient body mass index [BMI], intravenous [IV] antibiotic use, pretransplant dialysis, and total bilirubin) were assigned weight using linear transformation, and risk scores were derived. Patients were grouped by predicted posttransplant mortality: low risk (≤ 38 points), medium risk (38-41 points), and high risk (≥ 42 points). We performed Cox proportional hazards analysis on wait-listed CF-LVAD patients who were not transplanted. Score significantly discriminated survival among the groups in the development cohort (6.7, 12.9, 20.7; p = 0.001), validation cohort (6.4, 10.1, 13.6; p < 0.001), and ambulatory cohort (6.4, 11.5, 17.2; p < 0.001). We derived a left ventricular assist device (LVAD) BTT risk score that effectively identifies CF-LVAD patients who are at higher risk for worse outcomes after heart transplant. This score may help physicians weigh the risks of transplantation in patients with CF-LVAD.

The NHLBI REVIVE-IT study: Understanding its discontinuation in the context of current left ventricular assist device therapy.

PubMed

Pagani, Francis D; Aaronson, Keith D; Kormos, Robert; Mann, Douglas L; Spino, Cathie; Jeffries, Neal; Taddei-Peters, Wendy C; Mancini, Donna M; McNamara, Dennis M; Grady, Kathleen L; Gorcsan, John; Petrucci, Ralph; Anderson, Allen S; Glick, Henry A; Acker, Michael A; Eduardo Rame, J; Goldstein, Daniel J; Pamboukian, Salpy V; Miller, Marissa A; Timothy Baldwin, J

2016-11-01

The National Institutes of Health National Heart, Lung, and Blood Institute convened a working group in March 2008 to discuss how therapies for heart failure (HF) might be best advanced using clinical trials involving left ventricular assist devices (LVAD). This group opined that the field was ready for a trial to assess the use of long-term ventricular assist device therapy in patients who are less ill than patients currently eligible for destination therapy, which resulted in the Randomized Evaluation of VAD InterVEntion before Inotropic Therapy (REVIVE-IT) pilot study. The specific objective of REVIVE-IT was to compare LVAD therapy with optimal medical management in patients with less advanced HF than current LVAD indications to determine if wider application of permanent LVAD use to less ill patients would be associated with improved survival, quality of life, or functional capacity. REVIVE-IT represented an extraordinary effort to provide data from a randomized clinical trial to inform clinicians, scientists, industry, and regulatory agencies about the efficacy and safety of LVAD therapy in a population with less advanced HF. Despite significant support from the medical community, industry, and governmental agencies, REVIVE-IT failed to accomplish its goal. The reasons for its failure are instructive, and the lessons learned from the REVIVE-IT experience are likely to be relevant to any future study of LVAD therapy in a population with less advanced HF. Copyright © 2016 International Society for Heart and Lung Transplantation. All rights reserved.

In Vivo Evaluation of Active and Passive Physiological Control Systems for Rotary Left and Right Ventricular Assist Devices.

PubMed

Gregory, Shaun D; Stevens, Michael C; Pauls, Jo P; Schummy, Emma; Diab, Sara; Thomson, Bruce; Anderson, Ben; Tansley, Geoff; Salamonsen, Robert; Fraser, John F; Timms, Daniel

2016-09-01

Preventing ventricular suction and venous congestion through balancing flow rates and circulatory volumes with dual rotary ventricular assist devices (VADs) configured for biventricular support is clinically challenging due to their low preload and high afterload sensitivities relative to the natural heart. This study presents the in vivo evaluation of several physiological control systems, which aim to prevent ventricular suction and venous congestion. The control systems included a sensor-based, master/slave (MS) controller that altered left and right VAD speed based on pressure and flow; a sensor-less compliant inflow cannula (IC), which altered inlet resistance and, therefore, pump flow based on preload; a sensor-less compliant outflow cannula (OC) on the right VAD, which altered outlet resistance and thus pump flow based on afterload; and a combined controller, which incorporated the MS controller, compliant IC, and compliant OC. Each control system was evaluated in vivo under step increases in systemic (SVR ∼1400-2400 dyne/s/cm(5) ) and pulmonary (PVR ∼200-1000 dyne/s/cm(5) ) vascular resistances in four sheep supported by dual rotary VADs in a biventricular assist configuration. Constant speed support was also evaluated for comparison and resulted in suction events during all resistance increases and pulmonary congestion during SVR increases. The MS controller reduced suction events and prevented congestion through an initial sharp reduction in pump flow followed by a gradual return to baseline (5.0 L/min). The compliant IC prevented suction events; however, reduced pump flows and pulmonary congestion were noted during the SVR increase. The compliant OC maintained pump flow close to baseline (5.0 L/min) and prevented suction and congestion during PVR increases. The combined controller responded similarly to the MS controller to prevent suction and congestion events in all cases while providing a backup system in the event of single controller failure

Exercise physiology, testing, and training in patients supported by a left ventricular assist device.

PubMed

Loyaga-Rendon, Renzo Y; Plaisance, Eric P; Arena, Ross; Shah, Keyur

2015-08-01

The left ventricular assist device (LVAD) is an accepted treatment alternative for the management of end-stage heart failure. As we move toward implantation of LVADs in less severe cases of HF, scrutiny of functional capacity and quality of life becomes more important. Patients demonstrate improvements in exercise capacity after LVAD implantation, but the effect is less than predicted. Exercise training produces multiple beneficial effects in heart failure patients, which would be expected to improve quality of life. In this review, we describe factors that are thought to participate in the persistent exercise impairment in LVAD-supported patients, summarize current knowledge about the effect of exercise training in LVAD-supported patients, and suggest areas for future research. Copyright © 2015 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

New therapy, new challenges: The effects of long-term continuous flow left ventricular assist device on inflammation.

PubMed

Grosman-Rimon, Liza; Billia, Filio; Fuks, Avi; Jacobs, Ira; A McDonald, Michael; Cherney, David Z; Rao, Vivek

2016-07-15

Surgically implanted continuous flow left ventricular assist devices (CF-LVADs) are currently used in patients with end-stage heart failure (HF). However, CF-LVAD therapy introduces a new set of complications and adverse events in these patients. Major adverse events with the CF-LVAD include right heart failure, vascular dysfunction, stroke, hepatic failure, and multi-organ failure, complications that may have inflammation as a common etiology. Our aim was to review the current evidence showing a relationship between these adverse events and elevated levels of inflammatory biomarkers in CF-LVAD recipients. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

HeartMate II left ventricular assist system: from concept to first clinical use.

PubMed

Griffith, B P; Kormos, R L; Borovetz, H S; Litwak, K; Antaki, J F; Poirier, V L; Butler, K C

2001-03-01

The HeartMate II left ventricular assist device (LVAD) (ThermoCardiosystems, Inc, Woburn, MA) has evolved from 1991 when a partnership was struck between the McGowan Center of the University of Pittsburgh and Nimbus Company. Early iterations were conceptually based on axial-flow mini-pumps (Hemopump) and began with purge bearings. As the project developed, so did the understanding of new bearings, computational fluid design and flow visualization, and speed control algorithms. The acquisition of Nimbus by ThermoCardiosystems, Inc (TCI) sped developments of cannulas, controller, and power/monitor units. The system has been successfully tested in more than 40 calves since 1997 and the first human implant occurred in July 2000. Multicenter safety and feasibility trials are planned for Europe and soon thereafter a trial will be started in the United States to test 6-month survival in end-stage heart failure.

Keeping Hearts Pumping

NASA Technical Reports Server (NTRS)

2002-01-01

A collaboration between NASA, Dr. Michael DeBakey, Dr. George Noon, and MicroMed Technology, Inc., resulted in a life-saving heart pump for patients awaiting heart transplants. The MicroMed DeBakey VAD functions as a "bridge to heart transplant" by pumping blood throughout the body to keep critically ill patients alive until a donor heart is available. Weighing less than 4 ounces and measuring 1 inch by 3 inches, the pump is approximately one-tenth the size of other currently marketed pulsatile VADs. This makes it less invasive and ideal for smaller adults and children. Because of the pump's small size, less than 5 percent of the patients implanted developed device-related infections. It can operate up to 8 hours on batteries, giving patients the mobility to do normal, everyday activities.The MicroMed DeBakey VAD is a registered trademark of MicroMed Technology, Inc.

Inpatient rehabilitation outcomes for patients receiving left ventricular assist device.

PubMed

Alsara, Osama; Reeves, Ronald K; Pyfferoen, Mary D; Trenary, Tamra L; Engen, Deborah J; Vitse, Merri L; Kessler, Stacy M; Kushwaha, Sudhir S; Clavell, Alfredo L; Thomas, Randal J; Lopez-Jimenez, Francisco; Park, Soon J; Perez-Terzic, Carmen M

2014-10-01

The aim of this study was to evaluate outcomes of patients participating in inpatient rehabilitation program after left ventricular assist device (LVAD) implantation. Medical records of 94 patients who received LVADs between January 1, 2008, and June 30, 2010, at the Mayo Clinic in Rochester, MN, were retrospectively reviewed for demographic data, and inpatient rehabilitation functional outcomes were measured by the Functional Independence Measure scale. After successful implantation of LVAD, the patients were either discharged directly home from acute care (44%) or admitted to inpatient rehabilitation (56%). The patients admitted to inpatient rehabilitation were older than those discharged home. They were also more medically complex and more likely to have the LVAD placed as destination therapy. At discharge, significant improvement occurred in 17 of the 18 activities evaluated by the Functional Independence Measure scale. The mean total Functional Independence Measure scale score at admission was 77.1 compared with a score of 95.2 at discharge (P < 0.0001). Approximately half of the patients who received LVAD therapy were admitted in the inpatient rehabilitation. After the implantation of LVAD and inpatient rehabilitation, significant functional improvements were observed. Further studies addressing the role of inpatient rehabilitation for LVAD patients are warranted.

Assessment of Safety and Effectiveness of the Extracorporeal Continuous-Flow Ventricular Assist Device (BR16010) Use as a Bridge-to-Decision Therapy for Severe Heart Failure or Refractory Cardiogenic Shock: Study Protocol for Single-Arm Non-randomized, Uncontrolled, and Investigator-Initiated Clinical Trial.

PubMed

Fukushima, Norihide; Tatsumi, Eisuke; Seguchi, Osamu; Takewa, Yoshiaki; Hamasaki, Toshimitsu; Onda, Kaori; Yamamoto, Haruko; Hayashi, Teruyuki; Fujita, Tomoyuki; Kobayashi, Junjiro

2018-06-08

The management of heart failure patients presenting in a moribund state remains challenging, despite significant advances in the field of ventricular assist systems. Bridge to decision involves using temporary devices to stabilize the hemodynamic state of such patients while further assessment is performed and a decision can be made regarding patient management. The purpose of this study (NCVC-BTD_01, National Cerebral and Cardiovascular Center-Bridge to Dicision_01) is to assess the safety and effectiveness of the newly developed extracorporeal continuous-flow ventricular assist system employing a disposable centrifugal pump with a hydrodynamically levitated bearing (BR16010) use as a bridge-to-decision therapy for patients with severe heart failure or refractory cardiogenic shock. NCVC-BTD_01 is a single-center, single-arm, open-label, exploratory, medical device, investigator-initiated clinical study. It is conducted at the National Cerebral and Cardiovascular Center in Japan. A total of nine patients will be enrolled in the study. The study was planned using Simon's minimax two-stage phase design. The primary endpoint is a composite of survival free of device-related serious adverse events and complications during device support. For left ventricular assistance, withdrawal of a trial device due to cardiac function recovery or exchange to other ventricular assist devices (VADs) for the purpose of bridge to transplantation (BTT) during 30 days after implantation will be considered study successes. For right ventricular assistance, withdrawal of tal device due to right ventricular function recovery within 30 days after implantation will be considered a study success. Secondary objectives include changes in brain natriuretic peptide levels (7 days after implantation of a trial device and the day of withdrawal of a trial device), period of mechanical ventricular support, changes in left ventricular ejection fraction (7 days after implantation of a trial device

14 CFR Appendix A to Part 1250 - NASA Federal Financial Assistance to Which This Part Applies

Code of Federal Regulations, 2011 CFR

2011-01-01

... RIGHTS ACT OF 1964 Pt. 1250, App. A Appendix A to Part 1250—NASA Federal Financial Assistance to Which... organizations whose primary purpose is the conduct of scientific research, wherein title to equipment purchased...

"Pseudo" Faraday cage: a solution for telemetry link interaction between a left ventricular assist device and an implantable cardioverter defibrillator.

PubMed

Jacob, Sony; Cherian, Prasad K; Ghumman, Waqas S; Das, Mithilesh K

2010-09-01

Patients implanted with left ventricular assist devices (LVAD) may have implantable cardioverter defibrillators (ICD) implanted for sudden cardiac death prevention. This opens the possibility of device-device communication interactions and thus interferences. We present a case of such interaction that led to ICD communication failure following the activation of an LVAD. In this paper, we describe a practical solution to circumvent the communication interference and review the communication links of ICDs and possible mechanisms of ICD-LVAD interactions.

Total vascular resistance and blood flow frequency during left ventricular assistance using a vibrating flow pump.

PubMed

Kobayashi, S; Owada, N; Yambe, T; Nitta, S; Fukuju, T; Hongoh, T; Hashimoto, H

1999-08-01

A vibrating flow pump (VFP) can generate high frequency oscillated blood flow within 10-30 Hz by the oscillation of its central tube. A totally implantable artificial heart using a VFP is being developed as a unique type of blood pump. In this study, left ventricular (LV) assist circulation was performed using a VFP. The total vascular resistance and driving frequency of the VFP were estimated from their relationship. The effect of oscillation on the vascular system was studied by the frequency analysis method and vascular impedance. Adult goats were anesthetized by halothane using an inhaler and a left fourth thoracotomy was performed. The inflow cannula was inserted into the left ventricle, and the outflow cannula was sutured to the descending aorta. The VFP and a centrifugal pump were set in parallel for alternation and comparison. The driving frequency of the VFP was changed and included 15, 20, 25, and 30 Hz. The hemodynamic parameters were continuously recorded during experiments by a digital audio tape (DAT) data recorder. The internal pressure of the left ventricular cavity and aortic pressure were monitored by the pressure manometers continuously. One hundred percent LV assistance was judged by the separation of LV and aortic pressure. The total vascular resistance was decreased by the start of operation of each pump. The decrease during flow using the VFP was not as large as that using a centrifugal pump (CP). The arterial input impedance during oscillated blood flow by the VFP showed a slow curve appearance. It was similar to the frequency characteristics curve of natural heart beats within the lower frequencies. The study of arterial impedance may be important for the estimation of the reflection of the pulsatile wave from the arterial branch, among other things.

Noncardiac Surgical Procedures After Left Ventricular Assist Device Implantation.

PubMed

Taghavi, Sharven; Jayarajan, Senthil N; Ambur, Vishnu; Mangi, Abeel A; Chan, Elaine; Dauer, Elizabeth; Sjoholm, Lars O; Pathak, Abhijit; Santora, Thomas A; Goldberg, Amy J; Rappold, Joseph F

2016-01-01

As left ventricular assist devices (LVADs) are increasingly used for patients with end-stage heart failure, the need for noncardiac surgical procedures (NCSs) in these patients will continue to rise. We examined the various types of NCS required and its outcomes in LVAD patients requiring NCS. The National Inpatient Sample Database was examined for all patients implanted with an LVAD from 2007 to 2010. Patients requiring NCS after LVAD implantation were compared to all other patients receiving an LVAD. There were 1,397 patients undergoing LVAD implantation. Of these, 298 (21.3%) required 459 NCS after LVAD implantation. There were 153 (33.3%) general surgery procedures, with abdominal/bowel procedures (n = 76, 16.6%) being most common. Thoracic (n = 141, 30.7%) and vascular (n = 140, 30.5%) procedures were also common. Patients requiring NCS developed more wound infections (9.1 vs. 4.6%, p = 0.004), greater bleeding complications (44.0 vs. 24.8%, p < 0.001) and were more likely to develop any complication (87.2 vs. 82.0%, p = 0.001). On multivariate analysis, the requirement of NCSs (odds ratio: 1.45, 95% confidence interval: 0.95-2.20, p = 0.08) was not associated with mortality. Noncardiac surgical procedures are commonly required after LVAD implantation, and the incidence of complications after NCS is high. This suggests that patients undergoing even low-risk NCS should be cared at centers with treating surgeons and LVAD specialists.

Role of ventricular assist therapy for patients with heart failure and restrictive physiology: Improving outcomes for a lethal disease.

PubMed

Grupper, Avishay; Park, Soon J; Pereira, Naveen L; Schettle, Sarah D; Gerber, Yariv; Topilsky, Yan; Edwards, Brooks S; Daly, Richard C; Stulak, John M; Joyce, Lyle D; Kushwaha, Sudhir S

2015-08-01

Restrictive cardiomyopathy (RCM) patients have poor prognosis due to progressive heart failure characterized by impaired ventricular filling of either or both ventricles. The goal of this study was to evaluate the outcome of end-stage RCM patients after left ventricular assist device (LVAD) implantation and to determine factors that may be associated with improved survival. This investigation is a retrospective study of prospectively collected data that include 28 consecutive patients with end-stage RCM who received continuous-flow LVADs at the Mayo Clinic, Rochester, Minnesota. Outcome was assessed by survival with LVAD support until heart transplantation or all-cause mortality. The mean follow-up time post-LVAD implantation was 448 ± 425 days. The mean hospitalization time was 29 ± 19 days and was complicated mainly by post-operative right ventricular (RV) failure requiring short-term medical support. The short-term in-hospital mortality was 14%. Ten patients underwent heart transplantation with 100% survival post-transplant during the follow-up period. One-year survival for patients with LVADs without transplantation was 64%, and was not significantly different between amyloidosis and non-amyloidosis patients. Larger left ventricle (LV) end-diastolic and end-systolic dimensions were significantly associated with improved survival rates (RR = 0.94 and 0.95, p < 0.05, respectively), and left ventricular end-diastolic diameter (LVEDD) ≤46 mm was associated with increased mortality post-LVAD implantation. LVAD is a feasible, life-saving therapy for end-stage heart failure related to RCM, especially as a bridge to transplant and in patients with larger LV dimensions. Copyright © 2015 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

Suction prevention and physiologic control of continuous flow left ventricular assist devices using intrinsic pump parameters.

PubMed

Wang, Yu; Koenig, Steven C; Slaughter, Mark S; Giridharan, Guruprasad A

2015-01-01

The risk for left ventricular (LV) suction during left ventricular assist devices (LVAD) support has been a clinical concern. Current development efforts suggest LVAD suction prevention and physiologic control algorithms may require chronic implantation of pressure or flow sensors, which can be unreliable because of baseline drift and short lifespan. To overcome this limitation, we designed a sensorless suction prevention and physiologic control (eSPPC) algorithm that only requires LVAD intrinsic parameters (pump speed and power). Two gain-scheduled, proportional-integral controllers maintain a differential pump speed (ΔRPM) above a user-defined threshold to prevent LV suction while maintaining an average reference differential pressure (ΔP) between the LV and aorta. ΔRPM is calculated from noisy pump speed measurements that are low-pass filtered, and ΔP is estimated using an extended Kalman filter. Efficacy and robustness of the eSPPC algorithm were evaluated in silico during simulated rest and exercise test conditions for 1) excessive ΔP setpoint (ES); 2) rapid eightfold increase in pulmonary vascular resistance (PVR); and 3) ES and PVR. Simulated hemodynamic waveforms (LV pressure and volume; aortic pressure and flow) using only intrinsic pump parameters showed the feasibility of our proposed eSPPC algorithm in preventing LV suction for all test conditions.

Computational Fluid Dynamics Analysis of Thrombosis Potential In Left Ventricular Assist Device Drainage Cannulae

PubMed Central

Fraser, Katharine H; Zhang, Tao; Taskin, M Ertan; Griffith, Bartley P; Wu, Zhongjun J

2010-01-01

Cannulation is necessary when blood is removed from the body, for example in hemodialysis, cardiopulmonary bypass, blood oxygenators, and ventricular assist devices. Artificial blood contacting surfaces are prone to thrombosis, especially in the presence of stagnant or recirculating flow. In this work, computational fluid dynamics was used to investigate the blood flow fields in three clinically available cannulae (Medtronic DLP 12, 16 and 24 F), used as drainage for pediatric circulatory support, and to calculate parameters which may be indicative of thrombosis potential. The results show that using the 24 F cannula below flow rates of about 0.75 l/min produces hemodynamic conditions which may increase the risk of blood clotting within the cannula. No reasons are indicated for not using the 12 or 16 F cannulae with flow rates between 0.25 and 3.0 l/min. PMID:20400890

Results of the post-market Registry to Evaluate the HeartWare Left Ventricular Assist System (ReVOLVE).

PubMed

Strueber, Martin; Larbalestier, Robert; Jansz, Paul; Zimpfer, Daniel; Fiane, Arnt E; Tsui, Steven; Simon, André; Schmitto, Jan D; Khaghani, Asghar; Wieselthaler, George M; Najarian, Kevin; Schueler, Stephan

2014-05-01

The post-market Registry to Evaluate the HeartWare Left Ventricular Assist System (ReVOLVE) is an investigator-initiated registry established to collect post-CE Mark Trial clinical data on patients receiving a HeartWare ventricular assist device (HVAD) in the European Union and Australia. The ReVOLVE is a multi-center, prospective, single-arm registry performed at seven centers in Europe and two in Australia. Herein we describe a total of 254 commercial HVAD implants according to labeled indications between February 2009 and November 2012. Summary statistics included patients' demographics, adverse events, length of support and outcomes. Compared with the clinical trial supporting the CE Mark of the HeartWare system, patient selection differed in that patients were older, and there were higher proportions of females and patients with idiopathic cardiomyopathies in the ReVOLVE cohort. Duration of support ranged from 1 to 1,057 days, with a mean of 363 ± 280 days (median 299.5 days). Transplantation was done in 56 patients (22%), explant for recovery was performed in 3 patients (1%), 43 died while on support (17%), and 152 (60%) remain on the device. Success in patients with the HeartWare system was 87% at 6 months, 85% at 1 year, 79% at 2 years and 73% at 3 years. Adverse event rates were low, comparable or improved when compared to the CE Mark Trial. Real-world use of the HeartWare system continues to demonstrate excellent clinical outcomes in patients supported with the device. Copyright © 2014 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

Outflow monitoring of a pneumatic ventricular assist device using external pressure sensors.

PubMed

Kang, Seong Min; Her, Keun; Choi, Seong Wook

2016-08-25

In this study, a new algorithm was developed for estimating the pump outflow of a pneumatic ventricular assist device (p-VAD). The pump outflow estimation algorithm was derived from the ideal gas equation and determined the change in blood-sac volume of a p-VAD using two external pressure sensors. Based on in vitro experiments, the algorithm was revised to consider the effects of structural compliance caused by volume changes in an implanted unit, an air driveline, and the pressure difference between the sensors and the implanted unit. In animal experiments, p-VADs were connected to the left ventricles and the descending aorta of three calves (70-100 kg). Their outflows were estimated using the new algorithm and compared to the results obtained using an ultrasonic blood flow meter (UBF) (TS-410, Transonic Systems Inc., Ithaca, NY, USA). The estimated and measured values had a Pearson's correlation coefficient of 0.864. The pressure sensors were installed at the external controller and connected to the air driveline on the same side as the external actuator, which made the sensors easy to manage.

Performance characterization of a rotary centrifugal left ventricular assist device with magnetic suspension.

PubMed

Jahanmir, Said; Hunsberger, Andrew Z; Heshmat, Hooshang; Tomaszewski, Michael J; Walton, James F; Weiss, William J; Lukic, Branka; Pae, William E; Zapanta, Conrad M; Khalapyan, Tigran Z

2008-05-01

The MiTiHeart (MiTiHeart Corporation, Gaithersburg, MD, USA) left ventricular assist device (LVAD), a third-generation blood pump, is being developed for destination therapy for adult heart failure patients of small to medium frame that are not being served by present pulsatile devices. The pump design is based on a novel, patented, hybrid passive/active magnetic bearing system with backup hydrodynamic thrust bearing and exhibits low power loss, low vibration, and low hemolysis. Performance of the titanium alloy prototype was evaluated in a series of in vitro tests with blood analogue to map out the performance envelop of the pump. The LVAD prototype was implanted in a calf animal model, and the in vivo pump performance was evaluated. The animal's native heart imparted a strong pulsatility to the flow rate. These tests confirmed the efficacy of the MiTiHeart LVAD design and confirmed that the pulsatility does not adversely affect the pump performance.

The impact of extreme obesity on outcomes after left ventricular assist device implantation.

PubMed

Yost, Gardner; Coyle, Laura; Gallagher, Colleen; Graney, Nicole; Siemeck, Roxanne; Tatooles, Antone; Pappas, Patroklos; Bhat, Geetha

2017-11-01

The association between extreme body mass index (BMI) and outcomes in left ventricular assist device (LVAD) patients has not been well established. With the commercial use of LVADs a larger number of patients with a BMI >40 have undergone device implantation. The purpose of this study was to evaluate the short and long-term outcomes of LVAD patients with extreme obesity. A retrospective review of all patients (n=383) at our center who received a LVAD as primary implant between 2005-2015 was performed. Demographics, preoperative laboratory values, and postoperative outcomes were analyzed. Patients were divided into three groups based on BMI (kg/m 2 ) classification (group 1: ≤25; group 2: 25 to 35; group 3: ≥35) and compared using one-way analysis of variance (ANOVA), Kruskal-Wallis and Chi-squared analysis as appropriate. Comparison of postoperative outcomes demonstrated an increased risk of respiratory failure and right ventricular (RV) failure in patients with a BMI ≥35 (range, 35-59). Length of stay, sternal infection, driveline/pocket infection, systemic infection, GI-bleeding, and neurological events within the first year of device therapy were not related to BMI. Survival at 30-day, 1- and 2-year was not significantly different among the three groups. The group with the smallest BMI demonstrated an increased risk for re-operative bleeding. Despite an increased risk of early morbidity in patients with extreme obesity, long term survival was not significantly different between the BMI groups. Careful consideration is recommended when evaluating patients with an excessive BMI for LVAD therapy although it should not be a contraindication for device placement.

Selling to NASA

NASA Technical Reports Server (NTRS)

1990-01-01

This handbook is designed to promote a better understanding of NASA's interests and the process of doing business with NASA. The document is divided into the following sections: (1) this is NASA; (2) the procurement process; (3) marketing your capabilities; (4) special assistance programs; (5) NASA field installations; (6) sources of additional help; (7) listing of NASA small/minority business personnel; and (8) NASA organization chart.

Pediatric experience with the VentrAssist LVAD.

PubMed

Ruygrok, Peter N; Esmore, Don S; Alison, Peter M; Finucane, Kirsten A; McGuinness, Shay P; McGeorge, Alastair D; Negri, Justin; Jones, Kylie; Gibbs, Helen C

2008-08-01

The purpose of this study is to describe the first experience of implanting a new left ventricular assist device in pediatric patients with end-stage heart failure. In two recent prospective, international, multicenter clinical trials, three children (aged Assist (Ventracor Limited, Chatswood, Australia), a relatively small, novel, continuous flow, third-generation left ventricular assist device. Despite the patients' disease severity (each child was in extremis at the time of implantation), VentrAssist (Ventracor Limited) implantation enabled each patient to be discharged home from the hospital. All patients survived for more than 1 year. One patient was successfully transplanted and another was bridged to an adequate degree of recovery; unfortunately, the third patient died on postoperative day 375 while waiting for a suitable donor heart. Consistent with the complications associated with left ventricular assist devices in adults, the main complications in these pediatric patients were infection and thromboembolism. The VentrAssist may provide a major advancement in the management of larger children and adolescents with end-stage heart failure.

Right Ventricular Failure Post LVAD Implantation Corrected with Biventricular Support: An In Vitro Model.

PubMed

Shehab, Sajad; Allida, Sabine M; Davidson, Patricia M; Newton, Phillip J; Robson, Desiree; Jansz, Paul C; Hayward, Christopher S

Right ventricular failure after left ventricular assist device (LVAD) implantation is associated with high mortality. Management remains limited to pharmacologic therapy and temporary mechanical support. Delayed right ventricular assist device (RVAD) support after LVAD implantation is associated with poorer outcomes. With the advent of miniaturized, durable, continuous flow ventricular assist device systems, chronic RVAD and biventricular assist device (BiVAD) support has been used with some success. The purpose of this study was to assess combined BiVAD and LVAD with delayed RVAD support within a four-elemental mock circulatory loop (MCL) simulating the human cardiovascular system. Our hypothesis was that delayed continuous flow RVAD (RVAD) would produce similar hemodynamic and flow parameters to those of initial BiVAD support. Using the MCL, baseline biventricular heart failure with elevated right and left filling pressures with low cardiac output was simulated. The addition of LVAD within a biventricular configuration improved cardiac output somewhat, but was associated with persistent right heart failure with elevated right-sided filling pressures. The addition of an RVAD significantly improved LVAD outputs and returned filling pressures to normal throughout the circulation. In conclusion, RVAD support successfully restored hemodynamics and flow parameters of biventricular failure supported with isolated LVAD with persistent elevated right atrial pressure.

How NASA's Space Science Support Network Can Assist DPS Members in Their Public Engagement Efforts

NASA Astrophysics Data System (ADS)

Miner, E. D.; Lowes, L. L.

2003-12-01

In her Carl Sagan Medal lecture last year, Heidi Hammel talked of the dos and don'ts of education and public outreach efforts by DPS members. She pointed out a number of misconceptions about what does and does not constitute "good EPO" and encouraged members to consult with "the experts" if they would like to improve their EPO effectiveness and reach. She named the DPS Education and Public Outreach Officer, Larry Lebofsky, his Deputy, Lou Mayo, and the DPS Press Officer, Ellis Miner, who also co-directs NASA's Solar System Exploration EPO Forum with Leslie Lowes. NASA's Space Science Support Network has been in existence for about six years. It has been directed by DPS member Jeff Rosendhal and is now serving as a model for NASA's new Education Enterprise. Members of the Support Network are prepared to assist (and haves been assisting) space scientists throughout the US and abroad in deciding where to spend their EPO efforts most effectively. The service is provided free of cost and includes, among other services, the following: (1) helping to establish partnerships between educators and scientists, (2) helping to link scientists and professional EPO organizations, (3) helping to link scientists to national youth and community groups, (4) providing ready access to EPO electronic and hardcopy products, (5) providing advice and direction in the preparation of EPO proposals to NASA, (6) helping to maintain several national networks of EPO volunteers, (7) encouraging (at home institutions) the broadening of scientist EPO efforts, (8) maintaining self-help websites for scientists interested in EPO.

Feasibility of a tiny Gyro centrifugal pump as an implantable ventricular assist device.

PubMed

Yoshikawa, M; Nakata, K; Ohtsuka, G; Takano, T; Glueck, J; Fujisawa, A; Makinouchi, K; Yokokawa, M; Nosé, Y

1999-08-01

The Gyro pumps were developed for long-term circulatory support. The first generation Gyro pump (C1E3) achieved 1 month paracorporeal circulatory support in chronic animal experiments; the second generation (PI702) implantable ventricular assist device (VAD) was successful for over 6 months. The objective of the next generation Gyro pump is for use as a long-term totally implantable VAD and for pediatric circulatory support. This tiny Gyro pump (KP101) was fabricated with the same design concept as the other Gyro pumps. The possibility of an implantable VAD was determined after performance and hemolysis test results were compared to those of the other Gyro pumps. The pump housing and impeller were fabricated from polycarbonate with an impeller diameter of 35 mm. The diameter and height of the pump housings are 52.3 mm and 29.9 mm, respectively. At this time, a DC brushless motor drives the KP101, which is the same as that for the C1E3. The pump performance was measured in 37% glycerin water at 37 degrees C. Hemolysis tests were performed utilizing a compact mock loop filled with fresh bovine blood in a left ventricular assist device (LVAD) condition at 37 degrees C. The KP101 achieved the LVAD conditions of 5 L/min and 100 mm Hg at 2,900 rpm; generated 10 L/min against 100 mm Hg at 3,200 rpm; 3 L/min against 90 mm Hg at 2,600 rpm; and 2 L/min against 80 mm Hg at 2,400 rpm. In addition, the pump efficiency during this experiment was 12.5%. The other Gyro pumps. that is, the C1E3, PI601, and PI701, in an LVAD condition require 1,600, 2,000, and 2,000 rpm, respectively. The KP101 produced a normalized index of hemolysis (NIH) value of 0.005 g/100 L. With regard to the NIH, the other Gyro pumps, namely the C1E3, PI601, and PI701 demonstrated 0.0007, 0.0028, and 0.004 g/100 L, respectively. The KP101 produced an acceptable pressure flow curve for a VAD. The NIH value was higher than that of other Gyro pumps, but is in an acceptable range.

Using hybrid magnetic bearings to completely suspend the impeller of a ventricular assist device.

PubMed

Khanwilkar, P; Olsen, D; Bearnson, G; Allaire, P; Maslen, E; Flack, R; Long, J

1996-06-01

Clinically available blood pumps and those under development suffer from poor mechanical reliability and poor biocompatibility related to anatomic fit, hemolysis, and thrombosis. To alleviate these problems concurrently in a long-term device is a substantial challenge. Based on testing the performance of a prototype, and on our judgment of desired characteristics, we have configured an innovative ventricular assist device, the CFVAD4, for long-term use. The design process and its outcome, the CFVAD4 system configuration, is described. To provide unprecedented reliability and biocompatibility, magnetic bearings completely suspend the rotating pump impeller. The CFVAD4 uses a combination of passive (permanent) and active (electric) magnetic bearings, a mixed flow impeller, and a slotless 3-phase brushless DC motor. These components are shaped, oriented, and integrated to provide a compact, implantable, pancake-shaped unit for placement in the left upper abdominal quadrant of adult humans.

Evaluation of left ventricular assist device pump bladders cast from ion-sputtered polytetrafluorethylene mandrels

NASA Technical Reports Server (NTRS)

1982-01-01

A highly thromboresistant blood contacting interface for use in implanatable blood pump is investigated. Biomaterials mechanics, dynamics, durability, surface morphology, and chemistry are among the critical consideration pertinent to the choice of an appropriate blood pump bladder material. The use of transfer cast biopolymers from ion beam textured surfaces is investigated to detect subtle variations in blood pump surface morphology using Biomer as the biomaterial of choice. The efficacy of ion beam sputtering as an acceptable method of fabricating textured blood interfaces is evaluated. Aortic grafts and left ventricular assist devices were implanted in claves; the blood interfaces were fabricated by transfer casting methods from ion beam textured polytetrafluorethylene mandrels. The mandrels were textured by superimposing a 15 micron screen mesh; ion sputtering conditions were 300 volts beam energy, 40 to 50 mA beam, and a mandrel to source distance of 25 microns.

Echocardiographic predictors of adverse outcomes after continuous left ventricular assist device implantation.

PubMed

Topilsky, Yan; Oh, Jae K; Shah, Dipesh K; Boilson, Barry A; Schirger, John A; Kushwaha, Sudhir S; Pereira, Naveen L; Park, Soon J

2011-03-01

The purpose of the study was to identify echocardiographic predictors of adverse outcome in patients implanted with continuous-flow left ventricular assist devices (LVAD). Continuous flow LVAD have become part of the standard of care for the treatment of advanced heart failure. However, knowledge of echocardiographic predictors of outcome after LVAD are lacking. Overall, 83 patients received continuous-flow LVAD (HeartMate II, Thoratec Corporation, Pleasanton, California) from February 2007 to June 2010. The LVAD database, containing various echocardiographic parameters, was examined to analyze their influence on in-hospital mortality, a compound cardiac event (in-hospital mortality or acute right ventricular [RV] dysfunction), and long-term mortality. Eight patients died before discharge (operative mortality 9.6%), and another 15 patients were considered to have acute RV dysfunction immediately after surgery. Patients with relatively small left ventricular end-diastolic diameters (<63 mm) had significantly higher risk for in-hospital mortality (odds ratio [OR]: 0.9; 95% confidence interval [CI]: 0.83 to 0.99; p = 0.04) or occurrence of the compound cardiac event (OR: 0.89; 95% CI: 0.84 to 0.95; p < 0.001). The most significant predictor of outcome was the decreased timing interval between the onset and the cessation of tricuspid regurgitation flow corrected for heart rate (TRDc), a surrogate for early systolic equalization of RV and right atrial pressure. Short TRDc predicted in-hospital mortality (OR: 0.85; 95% CI: 0.74 to 0.97; p = 0.01) and the compound cardiac event (OR: 0.83; 95% CI: 0.74 to 0.91; p < 0.0001). Multivariate analysis based on a logistic regression model demonstrated that the accuracy of predicting the 30-day compound adverse outcome was improved with the addition of echocardiographic variables when added to the commonly used hemodynamic or clinical scores. TRDc predicted long-term survival, with adjusted risk ratios of 0.89 for death from any

The Use of Computational Fluid Dynamics in the Development of Ventricular Assist Devices

PubMed Central

Fraser, Katharine H.; Taskin, M. Ertan; Griffith, Bartley P.; Wu, Zhongjun J.

2010-01-01

Progress in the field of prosthetic cardiovascular devices has significantly contributed to the rapid advancements in cardiac therapy during the last four decades. The concept of mechanical circulatory assistance was established with the first successful clinical use of heart-lung machines for cardiopulmonary bypass. Since then a variety of devices have been developed to replace or assist diseased components of the cardiovascular system. Ventricular assist devices (VADs) are basically mechanical pumps designed to augment or replace the function of one or more chambers of the failing heart. Computational Fluid Dynamics (CFD) is an attractive tool in the development process of VADs, allowing numerous different designs to be characterized for their functional performance virtually, for a wide range of operating conditions, without the physical device being fabricated. However, VADs operate in a flow regime which is traditionally difficult to simulate; the transitional region at the boundary of laminar and turbulent flow. Hence different methods have been used and the best approach is debatable. In addition to these fundamental fluid dynamic issues, blood consists of biological cells. Device-induced biological complications are a serious consequence of VAD use. The complications include blood damage (haemolysis, blood cell activation), thrombosis and emboli. Patients are required to take anticoagulation medication constantly which may cause bleeding. Despite many efforts blood damage models have still not been implemented satisfactorily into numerical analysis of VADs, which severely undermines the full potential of CFD. This paper reviews the current state of the art CFD for analysis of blood pumps, including a practical critical review of the studies to date, which should help device designers choose the most appropriate methods; a summary of blood damage models and the difficulties in implementing them into CFD; and current gaps in knowledge and areas for future

Cardiac Recovery During Long-Term Left Ventricular Assist Device Support.

PubMed

Wever-Pinzon, Omar; Drakos, Stavros G; McKellar, Stephen H; Horne, Benjamin D; Caine, William T; Kfoury, Abdallah G; Li, Dean Y; Fang, James C; Stehlik, Josef; Selzman, Craig H

2016-10-04

The number of centers with left ventricular assist device (LVAD) research programs focused on cardiac recovery is very small. Therefore, this phenomenon has been reported in real-world multi-center registries as a rare event. This study evaluated the incidence of cardiac recovery with an a priori LVAD implantation strategy of bridge-to-recovery (BTR) and constructed a recovery predictive model. The study included LVAD recipients registered in the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS). Cardiac recovery was evaluated in BTR and non-BTR patients. A weighted score was derived and externally validated in patients of the Utah Cardiac Recovery (UCAR) program. Of 15,138 INTERMACS patients, cardiac recovery occurred in 192 (1.3%). The incidence of recovery was 11.2% (n = 14) in BTR compared with 1.2% (n = 178) in non-BTR patients (p < 0.0001). Independent predictors of recovery included: age <50 years, non-ischemic cardiomyopathy, time from cardiac diagnosis <2 years, absence of ICD, creatinine ≤1.2 mg/dl, and LVEDD <6.5 cm (c-index: 0.85; p < 0.0001). A weighted score termed I-CARS, effectively stratified patients based on their probability of recovery. I-CARS was validated in the UCAR cohort (n = 190) with good performance (AUC: 0.94; 95% CI: 0.91 to 0.98). One-year survival after LVAD explantation, available in INTERMACS for 21 (11%) patients, was 86%. The incidence of cardiac recovery is higher in patients implanted with an a priori BTR strategy. We developed a simple tool to help identify patients in whom recovery is feasible. In BTR patients with favorable characteristics, I-CARS suggests a 24% probability of successful LVAD explantation. Large-scale studies to better address post-explantation outcomes are warranted. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Readmissions after implantation of axial flow left ventricular assist device.

PubMed

Hasin, Tal; Marmor, Yariv; Kremers, Walter; Topilsky, Yan; Severson, Cathy J; Schirger, John A; Boilson, Barry A; Clavell, Alfredo L; Rodeheffer, Richard J; Frantz, Robert P; Edwards, Brooks S; Pereira, Naveen L; Stulak, John M; Joyce, Lyle; Daly, Richard; Park, Soon J; Kushwaha, Sudhir S

2013-01-15

The purpose of this study was to determine the occurrence and causes of readmissions after implantation of axial flow left ventricular assist device (LVAD). Based on the REMATCH (Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure) study experience, readmissions after LVAD implantation are thought to be frequent. We retrospectively analyzed admissions to our facility in a cohort of 115 patients implanted between January 2008 and July 2011 with the HeartMate II axial flow LVAD, of whom 42 were bridged to transplant. To account for repeated events, Andersen-Gill models were used to determine possible predictors. The patients were followed for 1.4 ± 0.9 years. There were 224 readmissions in 83 patients. The overall readmission rate was 1.64 ± 1.97 per patient-year of follow-up. The readmission rate for the first 6 months was 2.0 ± 2.3 and decreased to 1.2 ± 2.1 during subsequent follow-up. Leading causes were bleeding (66 readmissions in 34 patients), mostly gastrointestinal bleed (51 in 27 patients), cardiac (51 in 36 patients, most for HF or arrhythmia), infections (32 in 25 patients) of which 6 were pump related, and thrombosis (20 in 15 patients) including 13 readmissions due to hemolysis. Preoperative variables associated with (fewer) readmissions in a multivariate model include residence within our hospital-extended referral zone of Minnesota and the neighboring states (hazard ratio: 0.66; 95% confidence interval: 0.48 to 0.91; p = 0.011), hemoglobin (hazard ratio: 0.91, 95% confidence interval: 0.84 to 0.99; p = 0.027) and N-terminal pro-B-type natriuretic peptide (hazard ratio: 0.98; 95% confidence interval: 0.96 to 1.0 per 1,000-unit increase, p = 0.022). C-statistic for the model: 0.63. Readmission rates after axial flow LVAD implantation decrease during the first 6 months and then stabilize. The leading causes are bleeding, cardiac (heart failure and arrhythmia), infections, and thrombosis. Copyright © 2013

A practical review for cardiac rehabilitation professionals of continuous-flow left ventricular assist devices: historical and current perspectives.

PubMed

Compostella, Leonida; Russo, Nicola; Setzu, Tiziana; Bottio, Tomaso; Compostella, Caterina; Tarzia, Vincenzo; Livi, Ugolino; Gerosa, Gino; Iliceto, Sabino; Bellotto, Fabio

2015-01-01

An increasing number of patients with end-stage heart failure are being treated with continuous-flow left ventricular assist devices (cf-LVADs). These patients provide new challenges to the staff in exercise-based cardiac rehabilitation (CR) programs. Even though experience remains limited, it seems that patients supported by cf-LVADs may safely engage in typical rehabilitative activities, provided that some attention is paid to specific aspects, such as the presence of a short external drive line. In spite of initial physical deconditioning, CR allows progressive improvement of symptoms such as fatigue and dyspnea. Intensity of rehabilitative activities should ideally be based on measured aerobic capacity and increased appropriately over time. Regular, long-term exercise training results in improved physical fitness and survival rates. Appropriate adjustment of cf-LVAD settings, together with maintenance of adequate blood volume, provides maximal output, while avoiding suction effects. Ventricular arrhythmias, although not necessarily constituting an immediate life-threatening situation, deserve treatment as they could lead to an increased rate of hospitalization and poorer quality of life. Atrial fibrillation may worsen symptoms of right ventricular failure and reduce exercise tolerance. Blood pressure measurements are possible in cf-LVAD patients only using a Doppler technique, and a mean blood pressure ≤80 mmHg is considered "ideal." Some patients may present with orthostatic intolerance, related to autonomic dysfunction. While exercise training constitutes the basic rehabilitative tool, a comprehensive intervention that includes psychological and social support could better meet the complex needs of patients in which cf-LVAD may offer prolonged survival.

The paradox of left ventricular assist device unloading and myocardial recovery in end-stage dilated cardiomyopathy: implications for heart failure in the elderly.

PubMed

Butler, Craig R; Jugdutt, Bodh I

2012-09-01

Dilated cardiomyopathy (DCM) is a common debilitating condition with limited therapeutic options besides heart transplantation or palliation. It is characterized by maladaptive remodeling of cardiomyocytes, extracellular collagen matrix (ECCM) and left ventricular (LV) geometry which contributes to further dysfunction. LV assist devices (LVADs) can reverse adverse remodeling in end-stage DCM. However, there is a disconnect between the benefits of prolonged unloading with LVAD at molecular and cellular levels and the low rate of bridge to recovery (BTR). Potential explanations for this paradox include insufficient reverse ECCM remodeling and/or excessive reverse cardiomyocyte remodeling with atrophy. LVAD therapy is associated with decreased collagen turnover and cross-linking and increased tissue angiotensin II (AngII), whereas LVAD combined with angiotensin-converting enzyme inhibition results in decreased tissue AngII and collagen cross-linking, normalizes LV end-diastolic pressure volume relationships and is associated with modestly higher rates of BTR. Much remains to be learned about ventricular reverse remodeling after LVAD. This can be facilitated through systematic collection and comparison of recovered and unrecovered myocardium. Importantly, vigilant monitoring for ventricular recovery among LVAD patients is needed, particularly in older patients receiving LVAD for destination therapy. In addition, prospective multicenter trials are needed to clarify the potential benefit of concomitant heart failure therapy with selective β2 agonism on ventricular recovery.

Closing the gap in paediatric ventricular assist device therapy with the Berlin Heart EXCOR® 15-ml pump.

PubMed

De Rita, Fabrizio; Griselli, Massimo; Sandica, Eugen; Miera, Oliver; Karimova, Ann; d'Udekem, Yves; Goldwasser, Ranny; Januszewska, Katarzyna; Amodeo, Antonio; Jurrmann, Nadine; Ersel, Simon; Menon, Ares K

2017-05-01

The Berlin Heart EXCOR ® (EXCOR) paediatric ventricular assist device is used worldwide for mechanical support of infants and small children with end-stage heart failure. A clinically important gap between the smallest EXCOR blood pump (10 ml) and the next larger size (25 ml) limited the choice of pump size in patients with a body surface area (BSA) between 0.33 and 0.5 m 2 . We present the first clinical experience from the early product surveillance (EPS) of the new EXCOR 15-ml blood pump. After CE and U.S. Food and Drug Administration approval in January 2013, 20 patients with a mean age of 1.6 years (range 0.5-3.5 years) and a mean BSA of 0.45 m 2 (range 0.33-0.59 m 2 ) were enrolled in the EPS. The main diagnosis was idiopathic cardiomyopathy in 13 patients; the majority ( n =  16) of children were in INTERMACS level 1 or 2. Data from high-volume paediatric transplant centres were collected prospectively for a defined follow-up period of 60 days after device implantation. Mean time on the EXCOR 15-ml blood pump was 43 days; the survival rate was 100% at the end of the EPS period. Seven patients underwent a heart transplant from the device; 2 children were weaned; and 11 patients remained on support. Infection of cannula exit sites occurred in 3 patients. Two patients had minor thromboembolic strokes but made a complete neurological recovery. The new EXCOR 15-ml blood pump demonstrated optimal ventricular assist device support of children with a BSA of 0.33-0.5 m 2 . © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Effect of counter-pulsation control of a pulsatile left ventricular assist device on working load variations of the native heart.

PubMed

Choi, Seong Wook; Nam, Kyoung Won; Lim, Ki Moo; Shim, Eun Bo; Won, Yong Soon; Woo, Heung Myong; Kwak, Ho Hyun; Noh, Mi Ryoung; Kim, In Young; Park, Sung Min

2014-04-03

When using a pulsatile left ventricular assist device (LVAD), it is important to reduce the cardiac load variations of the native heart because severe cardiac load variations can induce ventricular arrhythmia. In this study, we investigated the effect of counter-pulsation control of the LVAD on the reduction of cardiac load variation. A ventricular electrocardiogram-based counter-pulsation control algorithm for a LVAD was implemented, and the effects of counter-pulsation control of the LVAD on the reduction of the working load variations of the left ventricle were determined in three animal experiments. Deviations of the working load of the left ventricle were reduced by 51.3%, 67.9%, and 71.5% in each case, and the beat-to-beat variation rates in the working load were reduced by 84.8%, 82.7%, and 88.2% in each ease after counter-pulsation control. There were 3 to 12 premature ventricle contractions (PVCs) before counter-pulsation control, but no PVCs were observed during counter-pulsation control. Counter-pulsation control of the pulsatile LVAD can reduce severe cardiac load variations, but the average working load is not markedly affected by application of counter-pulsation control because it is also influenced by temporary cardiac outflow variations. We believe that counter-pulsation control of the LVAD can improve the long-term safety of heart failure patients equipped with LVADs.

Computational analysis of pediatric ventricular assist device implantation to decrease cerebral particulate embolization.

PubMed

Nguyen, ThuyTien; Argueta-Morales, I Ricardo; Guimond, Stephen; Clark, William; Ceballos, Andres; Osorio, Ruben; Divo, Eduardo A; De Campli, William M; Kassab, Alain J

2016-01-01

Stroke is the most devastating complication after ventricular assist device (VAD) implantation with a 19% incidence and 65% mortality in the pediatric population. Current pediatric VAD technology and anticoagulation strategies alone are suboptimal. VAD implantation assisted by computational methods (CFD) may contribute reducing the risk of cerebral embolization. Representative three-dimensional aortic arch models of an infant and a child were generated. An 8 mm VAD outflow-graft (VAD-OG) anastomosed to the aorta was rendered and CFD was applied to study blood flow patterns. Particle tracks, originating in the VAD, were computed with a Lagrangian phase model and the percentage of particles entering the cerebral vessels was calculated. Eight implantation configurations (infant = 5 and child = 3) and 5 particle sizes (0.5, 1, 2, 3, and 4 mm) were considered. For the infant model, percentage of particles entering the cerebral vessels ranged from 15% for a VAD-OG anastomosed at 90° to the aorta, to 31% for 30° VAD-OG anastomosis (overall percentages: X(2) = 10,852, p < 0.0001). For the child model, cerebral embolization ranged from 9% for the 30° VAD-OG anastomosis to 15% for the 60° anastomosis (overall percentages: χ(2) = 10,323, p < 0.0001). Using detailed CFD calculations, we demonstrate that the risk of stroke depends significantly on the VAD implantation geometry. In turn, the risk probably depends on patient-specific anatomy. CFD can be used to optimize VAD implantation geometry to minimize stroke risk.

Developments in control systems for rotary left ventricular assist devices for heart failure patients: a review.

PubMed

AlOmari, Abdul-Hakeem H; Savkin, Andrey V; Stevens, Michael; Mason, David G; Timms, Daniel L; Salamonsen, Robert F; Lovell, Nigel H

2013-01-01

From the moment of creation to the moment of death, the heart works tirelessly to circulate blood, being a critical organ to sustain life. As a non-stopping pumping machine, it operates continuously to pump blood through our bodies to supply all cells with oxygen and necessary nutrients. When the heart fails, the supplement of blood to the body's organs to meet metabolic demands will deteriorate. The treatment of the participating causes is the ideal approach to treat heart failure (HF). As this often cannot be done effectively, the medical management of HF is a difficult challenge. Implantable rotary blood pumps (IRBPs) have the potential to become a viable long-term treatment option for bridging to heart transplantation or destination therapy. This increases the potential for the patients to leave the hospital and resume normal lives. Control of IRBPs is one of the most important design goals in providing long-term alternative treatment for HF patients. Over the years, many control algorithms including invasive and non-invasive techniques have been developed in the hope of physiologically and adaptively controlling left ventricular assist devices and thus avoiding such undesired pumping states as left ventricular collapse caused by suction. In this paper, we aim to provide a comprehensive review of the developments of control systems and techniques that have been applied to control IRBPs.

Long-term in vivo left ventricular assist device study for 284 days with Gyro PI pump.

PubMed

Ohtsuka, G; Nakata, K; Yoshikawa, M; Takano, T; Glueck, J; Sankai, Y; Takami, Y; Mueller, J; Sueoka, A; Letsou, G; Schima, H; Schmallegger, H; Wolner, E; Koyanagi, H; Fujisawa, A; Baldwin, J C; Nosé, Y

1999-06-01

A totally implantable centrifugal artificial heart has been developed. The plastic prototype, the Gyro PI 601, passed 2 day hemodynamic tests as a functional total artificial heart (TAH), 2 week screening tests for anti-thrombogenecity, and a 1 month system feasibility study. Based upon these results, a metallic prototype, the Gyro PI 700 series, was subjected to long-term in vivo left ventricular assist device (LVAD) studies of over 1 month. The Gyro PI 700 series has the same inner dimension and same characteristics of the Gyro PI 601 such as an eccentric inlet port, a double pivot bearing system, and a magnet coupling system. The PI metallic pump is also driven with the Vienna DC brushless motor actuator like the PI 601. The pump-actuator package was implanted in 3 calves in the preperitoneal space, bypassing from the left ventricular (LV) apex to the descending aorta. Case 1 achieved a 284 day survival. Case 2 was euthanized early at 72 postoperative days as a result of the functional obstruction of the inlet port due to the excessive growth of the calf. There was no blood clot inside the pumps of either case. Case 3 is on-going (22 days on July 24, 1998). During these periods, all cases showed no physiological abnormalities. In conclusion, the PI 700 series pump has excellent results as a long-term implantable LVAD.

Lessons learned from 150 continuous-flow left ventricular assist devices: a single institutional 7 year experience.

PubMed

Tsiouris, Athanasios; Paone, Gaetano; Nemeh, Hassan W; Brewer, Robert J; Borgi, Jamil; Hodari, Arielle; Morgan, Jeffrey A

2015-01-01

Continuous-flow (CF) left ventricular assist devices (LVADs) have become the standard of care for patients with advanced heart failure refractory to optimal medical therapy. The goal of this study was to review our 7 year single institutional experience with CF LVADs. Mean age was 50.4 + 12.5 (17-69) years for bridge-to-transplantation (BTT) patients and 57.6 + 10.4 (31-81) years for destination therapy (DT) patients (p < 0.001). Overall, 38 patients (26%) were female and 58 (41%) were African American. Etiology of heart failure was ischemic in 54 patients (37%) and nonischemic in 93 patients (63%). Overall survival at 30 days, 6 months, 12 months, and 2 years was 93%, 89%, 84%, and 81%, respectively. Gastrointestinal bleeding (GIB) was the most common complication (24%), followed by stroke (18%), right ventricular (RV) failure (18%), ventilator-dependent respiratory failure (10%), reoperation for bleeding (10%), and driveline infection (9%). These data demonstrate excellent survival with low mortality for both BTT and DT patients on long-term LVAD support. However, for LVAD therapy to become the gold standard for long-term treatment of end-stage heart failure and a plausible alternative to heart transplantation, we need to continue to improve the incidence of frequent postoperative complications, such as RV failure, driveline infections, strokes, and GIB.

Content Analysis of Social Media Related to Left Ventricular Assist Devices.

PubMed

Kostick, Kristin M; Blumenthal-Barby, Jennifer S; Wilhelms, Lidija A; Delgado, Estevan D; Bruce, Courtenay R

2015-09-01

Social media have the potential to offer important benefits for patient education, support, and shared decision making. Despite the proliferation of social media use during the past decade, little is known about the scope and quality of available information, or the purposes that social media sites serve for patient decisional and support needs. We conducted a mixed method study, including content analysis of social media and principal components analysis analysis of data sites discussing left ventricular assist device treatment for heart failure. This study explored aspects of interactivity, user-friendliness, appeal, medium, purpose, audience, and accuracy of information. Higher levels of interactivity (eg, posting comments) seem to enhance the appeal and usability of available information but also introduce greater potential for inaccuracy and inconsistency. The current lack of oversight into the content and quality of available information constitute a challenge for the reliable use of social media as forums for information-seeking and social network-based support. We conclude that social media outlets constitute a promising source of informational and psychosocial support for patients, caregivers, and candidates, and if used in conjunction with patient-provider dialog, can contribute to informed decision making by facilitating reflection and discussion of personal concerns, values, and informational needs. © 2015 American Heart Association, Inc.

Preoperative liver dysfunction influences blood product administration and alterations in circulating haemostatic markers following ventricular assist device implantation.

PubMed

Woolley, Joshua R; Kormos, Robert L; Teuteberg, Jeffrey J; Bermudez, Christian A; Bhama, Jay K; Lockard, Kathleen L; Kunz, Nicole M; Wagner, William R

2015-03-01

Preoperative liver dysfunction may influence haemostasis following ventricular assist device (VAD) implantation. The Model for End-stage Liver Disease (MELD) score was assessed as a predictor of bleeding and levels of haemostatic markers in patients with currently utilized VADs. Sixty-three patients (31 HeartMate II, 15 HeartWare, 17 Thoratec paracorporeal ventricular assist device) implanted 2001-11 were analysed for preoperative liver dysfunction (MELD) and blood product administration. Of these patients, 21 had additional blood drawn to measure haemostatic marker levels. Cohorts were defined based on high (≥18.0, n = 7) and low (<18.0, n = 14) preoperative MELD scores. MELD score was positively correlated with postoperative administration of red blood cell (RBC), platelet, plasma and total blood product units (TBPU) , as well as chest tube drainage and cardiopulmonary bypass time. Age and MELD were preoperative predictors of TBPU by multivariate analysis. The high-MELD cohort had higher administration of TBPU, RBC and platelet units and chest tube drainage postimplant. Similarly, patients who experienced at least one bleeding adverse event were more likely to have had a high preoperative MELD. The high-MELD group exhibited different temporal trends in F1 + 2 levels and platelet counts to postoperative day (POD) 55. D-dimer levels in high-MELD patients became elevated versus those for low-MELD patients on POD 55. Preoperative MELD score predicts postoperative bleeding in contemporary VADs. Preoperative liver dysfunction may also alter postoperative subclinical haemostasis through different temporal trends of thrombin generation and platelet counts, as well as protracted fibrinolysis. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Successful Implantation of a Left Ventricular Assist Device in a Patient with Heparin-Induced Thrombocytopenia and Thrombosis

PubMed Central

Garland, Cassandra; Somogyi, David

2014-01-01

Abstract: We report the case of a 27-year-old woman with signs of heparin-induced thrombocytopenia and thrombosis (HITT) and left heart failure presenting for urgent implantation of a left ventricular assist device (LVAD). HITT can occur in 4.2–6.1% of patients with LVADs. If the patient remains hemodynamically stable, implantation can be delayed for several months until the heparin/PF-4 antibodies decline allowing the use of heparin on cardiopulmonary bypass, However, in most cases related to cardiogenic shock, surgery cannot be delayed. We present the case of a patient who underwent implantation of a HeartMate II LVAD and discuss management strategy using bivalirudin during cardiopulmonary bypass. PMID:25208434

The role of cerebral hyperperfusion in postoperative neurologic dysfunction after left ventricular assist device implantation for end-stage heart failure.

PubMed

Lietz, Katherine; Brown, Kevin; Ali, Syed S; Colvin-Adams, Monica; Boyle, Andrew J; Anderson, David; Weinberg, Alan D; Miller, Leslie W; Park, Soon; John, Ranjit; Lazar, Ronald M

2009-04-01

Cerebral hyperperfusion is a life-threatening syndrome that can occur in patients with chronically hypoperfused cerebral vasculature whose normal cerebral circulation was re-established after carotid endarterectomy or angioplasty. We sought to determine whether the abrupt restoration of perfusion to the brain after left ventricular assist device (LVAD) implantation produced similar syndromes. We studied the role of increased systemic flow after LVAD implantation on neurologic dysfunction in 69 consecutive HeartMate XVE LVAD (Thoratec, Pleasanton, Calif) recipients from October 2001 through June 2006. Neurologic dysfunction was defined as postoperative permanent or transient central change in neurologic status, including confusion, focal neurologic deficits, visual changes, seizures, or coma for more than 24 hours within 30 days after LVAD implantation. We found that 19 (27.5%) patients had neurologic dysfunction, including encephalopathy (n = 11), coma (n = 3), and other complications (n = 5). The multivariate analysis showed that an increase in cardiac index from the preoperative baseline value (relative risk, 1.33 per 25% cardiac index increase; P = .01) and a previous coronary bypass operation (relative risk, 4.53; P = .02) were the only independent predictors of neurologic dysfunction. Reduction of left ventricular assist device flow in 16 of the 19 symptomatic patients led to improvement of symptoms in 14 (87%) patients. Our findings showed that normal flow might overwhelm cerebral autoregulation in patients with severe heart failure, suggesting that cerebral hyperperfusion is possible in recipients of mechanical circulatory support with neurologic dysfunction.

Assessment of a new silicone tri-leaflet valve seamlessly assembled with blood chamber for a low-cost ventricular assist device.

PubMed

Hirai, S; Fukunaga, S; Sueshiro, M; Watari, M; Sueda, T; Matsuura, Y

1998-06-01

We have developed a practical, low-cost ventricular assist device (VAD) comprising a newly designed blood chamber with a silicone lenticular sac and two silicone tri-leaflet valves (STV), made en bloc. This new VAD is seamless, can be made cost-effectively and assembled with the blood chamber and valve as one body. This novel design should reduce the incident of thrombus formation because of the absence of a junction at the connecting ring and because of the use of flexible silicone materials which have both antithrombogenecity and biocompatibility. In in vitro hemodynamics testing, a batch of 3 consecutively manufactured VADs with STVs underwent hydrodynamic functional testing. These showed less regurgitation, a lower value of water hammer phenomenon, and a slightly greater pressure gradient across the valves than a mechanical valve (MV) [Björk-Shiley monostrut valve]. The flow and pulsatile efficiency were adequate and similar to that of a VAD with MVs. In in vitro durability and hemolysis tests, a VAD with STV functioned well for 54 days and showed similar hemolytic profiles to a VAD with MVs. In an in vivo acute experiment using an adult sheep, our device was problem-free providing sufficient output as a left ventricular assist device (LVAD). Although it will be necessary to decrease the pressure gradient across this STV in the future, our device showed efficient performance as a practical land cost-effective VAD for short term use.

Massive Atenolol, Lisinopril, and Chlorthalidone Overdose Treated with Endoscopic Decontamination, Hemodialysis, Impella Percutaneous Left Ventricular Assist Device, and ECMO.

PubMed

Heise, C William; Beutler, David; Bosak, Adam; Orme, Geoffrey; Loli, Akil; Graeme, Kimberlie

2015-03-01

Overdose of cardiovascular medications is increasingly associated with morbidity and mortality. We present a case of substantial atenolol, chlorthalidone, and lisinopril overdose treated by multiple modalities with an excellent outcome. Aggressive medical intervention did not provide sufficient hemodynamic stability in this patient with refractory cardiogenic and distributive shock. Impella® percutaneous left ventricular assist device and extracorporeal membrane oxygenation provided support while the effects of the overdose subsided. We present concentrations demonstrating removal of atenolol with continuous venovenous hemodiafiltration. This is the first report of esophagogastroduo denoscopy decontamination of this overdose with a large pill fragment burden.

Decision-making for destination therapy left ventricular assist devices: implications for caregivers.

PubMed

McIlvennan, Colleen K; Jones, Jacqueline; Allen, Larry A; Lindenfeld, JoAnn; Swetz, Keith M; Nowels, Carolyn; Matlock, Daniel D

2015-03-01

Implanting centers often require the identification of a dedicated caregiver before destination therapy left ventricular assist device (DT LVAD) implantation; however, the caregiver experience surrounding this difficult decision is relatively unexplored. From October 2012 through July 2013, we conducted semistructured, in-depth interviews with caregivers of patients considering DT LVAD. Data were analyzed using a mixed inductive and deductive approach. We interviewed 17 caregivers: 10 caregivers of patients living with DT LVAD, 6 caregivers of patients who had died with DT LVAD, and 1 caregiver of a patient who had declined DT LVAD. The themes identified, which could also be considered dialectical tensions, are broadly interpreted under 3 domains mapping to decision context, process, and outcome: (1) the stark decision context, with tension between hope and reality; (2) the challenging decision process, with tension between wanting loved ones to live and wanting to respect loved ones' wishes; and (3) the downstream decision outcome, with tension between gratitude and burden. Decision-making surrounding DT LVAD should incorporate decision support for patients and caregivers. This should include a focus on caregiver burden and the predictable tensions that caregivers experience. © 2015 American Heart Association, Inc.

Clinical evaluation of the Novacor totally implantable ventricular assist system. Current status.

PubMed

Daniel, M A; Lee, J; LaForge, D H; Chen, H; Billich, J; Miller, P J; Ramasamy, N; Strauss, L R; Jassawalla, J S; Portner, P M

1991-01-01

The totally implantable Novacor left ventricular assist system (LVAS) is currently approaching clinical evaluation. In vivo testing and production are underway with National Institutes of Health (NIH) support. Activity over the past year has focused on manufacturing engineering, preproduction quality assurance, and in vivo experiment completion. Subsequent to successful completion of the NIH-sponsored, 2-year preclinical device readiness test (DRT), a number of refinements were identified and approved by the NIH technical/data review board. Most of these were necessitated by obsolescence or unavailability of electronic components and the decision to use only high reliability military (MIL) qualified electronic components and processes. A few additional refinements were identified to increase design margins, all of which were qualified by accelerated testing. The development of production processes, automated test programs, and MIL compliant environmental stress screening procedures was completed. Production of LVAS subsystems, including core electronic components (hybrids, application-specific integrated circuits, and surface mount boards), was initiated. Animal studies are underway. The clinical trial, at Presbyterian-University Hospital of Pittsburgh and St. Louis University Medical Center, awaits completion of in vivo experiments, protocol development, and Food and Drug Administration approval.

Development of a compact portable driver for a pneumatic ventricular assist device.

PubMed

Nishinaka, Tomohiro; Taenaka, Yoshiyuki; Tatsumi, Eisuke; Ohnishi, Hiroyuki; Homma, Akihiko; Shioya, Kyoko; Mizuno, Toshihide; Tsukiya, Tomonori; Mushika, Sadahiko; Hashiguchi, Yasuhiro; Suzuki, Akira; Kitamura, Soichiro

2007-01-01

The Toyobo-National Cardiovascular Center pneumatic ventricular assist device (Toyobo-NCVC VAD) is widely used in Japan; however, the current pneumatic drivers have some drawbacks, including their large size, heavy weight, and high power consumption. These issues cause difficulty with mobility and contribute to an unsatisfactory quality of life for patients. Because it is urgently necessary to improve patients' safety and quality of life, we have developed a compact, low-noise, portable VAD driver by utilizing an electrohydraulic actuator consisting of a brushless DC motor and a regenerative pump. This unit can be actuated for as long as 2 h with two rechargeable lightweight batteries as well as with external AC power. It is compact in size (33 x 25 x 43 cm) and light in weight (13 kg), and the unit is carried on a mobile wheeled cart. In vitro testing with a Toyobo-NCVC VAD demonstrated a sufficient pumping capacity of up to 8 l/min. We conclude that this newly-developed compact portable driver can provide a better quality of life and improved safety for patients using protracted pneumatic VAD support.

Is exercise training safe and beneficial in patients receiving left ventricular assist device therapy?

PubMed

Alsara, Osama; Perez-Terzic, Carmen; Squires, Ray W; Dandamudi, Sanjay; Miranda, William R; Park, Soon J; Thomas, Randal J

2014-01-01

Because a limited number of patients receive heart transplantation, alternative therapies, such as left ventricular assist device (LVAD) therapy, have emerged. Published studies have shown that LVAD implantation, by itself, improves exercise tolerance to the point where it is comparable to those with mild heart failure. The improvement in exercise capacity is maximally achieved 12 weeks after LVAD therapy and can continue even after explantation of the device. This effect varies, depending on the type of LVAD and exercise training. The available data in the literature on safety and benefits of exercise training in patients after LVAD implantation are limited, but the data that are available suggest that training trends to be safe and have an impact on exercise capacity in LVAD patients. Although no studies were identified on the role of cardiac rehabilitation programs in the management of LVAD patients, it appears that cardiac rehabilitation programs offer an ideal setting for the provision of supervised exercise training in this patient group.

Using Hybrid Magnetic Bearings to Completely Suspend the Impeller of a Ventricular Assist Device.

PubMed

Khanwilkar, Pratap; Olsen, Don; Bearnson, Gill; Allaire, Paul; Maslen, Eric; Flack, Ron; Long, James

1996-05-01

Clinically available blood pumps and those under development suffer from poor mechanical reliability and poor biocompatibility related to anatomic fit, hemolysis, and thrombosis. To alleviate these problems concurrently in a long-term device is a substantial challenge. Based on testing the performance of a prototype, and on our judgment of desired characteristics, we have configured an innovative ventricular assist device, the CF-VAD4, for long-term use. The design process and its outcome, the CFVAD4 system configuration, is described. To provide unprecedented reliability and biocompatibility, magnetic bearings completely suspend the rotating pump impeller. The CFVAD4 uses a combination of passive (permanent) and active (electric) magnetic bearings, a mixed flow impeller, and a slotless 3-phase brushless DC motor. These components are shaped, oriented, and integrated to provide a compact, implantable, pancake-shaped unit for placement in the left upper abdominal quadrant of adult humans. © 1996 International Society for Artificial Organs.

An ultimate, compact, seal-less centrifugal ventricular assist device: Baylor C-Gyro pump.

PubMed

Ohara, Y; Makinouchi, K; Orime, Y; Tasai, K; Naito, K; Mizuguchi, K; Shimono, T; Damm, G; Glueck, J; Takatani, S

1994-01-01

We have developed a compact, seal-less, all-purpose centrifugal pump, the Baylor C-Gyro pump, which is intended as a long-term ventricular assist device (VAD) as well as a cardiopulmonary bypass pump. In attaining this goal, we began with eliminating the shaft seals by adopting a pivot bearing system at the impeller shaft. In addition, a ring magnet encased in the bottom of the impeller was coupled magnetically to a driver magnet placed outside the pump housing (C1 Prototype). This first model yielded satisfactory performance in vitro with a flow rate of 8 L/min against 250 mm Hg at 2,400 rpm, and an index of hemolysis (IH) of 0.0083 g/100 L using bovine blood. In the second model, the C1 Eccentric Inlet Port Model, the inlet bearing support bar in the prototype were eliminated without reducing the prototype's performance. These designs for antithrombogenicity are being tested by the first in vivo experiment, which has lasted for more than 2 weeks.

Hemodynamic guidelines for design and control of a turbodynamic pediatric ventricular assist device.

PubMed

Uber, Bronwyn E; Webber, Steven A; Morell, Victor O; Antaki, James F

2006-01-01

The design of mechanical circulatory support devices typically requires a priori knowledge of the hemodynamic requirements of their intended use. These requirements are difficult to determine because of limited clinical experience. This is especially true for the pediatric population, for whom there is a dearth of longitudinal data. This report aims to provide both engineers and physicians with benchmarks for determining the optimal flow requirements and settings for pediatric ventricular assist devices that are currently being developed. Criteria were developed on the basis of estimates derived from various sources. The potential patient population was estimated by using the prevalence of children on the heart transplant waiting list and those placed on extracorporeal membrane oxygenation. Cardiac outputs were determined for individual weights and body surface areas, using published values for healthy and sick pediatric patients. The recommended pump range was optimized to include the most patients, while considering the design constraints. This study identifies a significant population of patients who would benefit from a device providing 0.52 to 1.92 l/min.

Computational analysis of an axial flow pediatric ventricular assist device.

PubMed

Throckmorton, Amy L; Untaroiu, Alexandrina; Allaire, Paul E; Wood, Houston G; Matherne, Gaynell Paul; Lim, David Scott; Peeler, Ben B; Olsen, Don B

2004-10-01

Longer-term (>2 weeks) mechanical circulatory support will provide an improved quality of life for thousands of pediatric cardiac failure patients per year in the United States. These pediatric patients suffer from severe congenital or acquired heart disease complicated by congestive heart failure. There are currently very few mechanical circulatory support systems available in the United States as viable options for this population. For that reason, we have designed an axial flow pediatric ventricular assist device (PVAD) with an impeller that is fully suspended by magnetic bearings. As a geometrically similar, smaller scaled version of our axial flow pump for the adult population, the PVAD has a design point of 1.5 L/min at 65 mm Hg to meet the full physiologic needs of pediatric patients. Conventional axial pump design equations and a nondimensional scaling technique were used to estimate the PVAD's initial dimensions, which allowed for the creation of computational models for performance analysis. A computational fluid dynamic analysis of the axial flow PVAD, which measures approximately 65 mm in length by 35 mm in diameter, shows that the pump will produce 1.5 L/min at 65 mm Hg for 8000 rpm. Fluid forces (approximately 1 N) were also determined for the suspension and motor design, and scalar stress values remained below 350 Pa with maximum particle residence times of approximately 0.08 milliseconds in the pump. This initial design demonstrated acceptable performance, thereby encouraging prototype manufacturing for experimental validation.

Thermal Analysis of the PediaFlow pediatric ventricular assist device.

PubMed

Gardiner, Jeffrey M; Wu, Jingchun; Noh, Myounggyu D; Antaki, James F; Snyder, Trevor A; Paden, David B; Paden, Brad E

2007-01-01

Accurate modeling of heat dissipation in pediatric intracorporeal devices is crucial in avoiding tissue and blood thermotrauma. Thermal models of new Maglev ventricular assist device (VAD) concepts for the PediaFlow VAD are developed by incorporating empirical heat transfer equations with thermal finite element analysis (FEA). The models assume three main sources of waste heat generation: copper motor windings, active magnetic thrust bearing windings, and eddy currents generated within the titanium housing due to the two-pole motor. Waste heat leaves the pump by convection into blood passing through the pump and conduction through surrounding tissue. Coefficients of convection are calculated and assigned locally along fluid path surfaces of the three-dimensional pump housing model. FEA thermal analysis yields a three-dimensional temperature distribution for each of the three candidate pump models. Thermal impedances from the motor and thrust bearing windings to tissue and blood contacting surfaces are estimated based on maximum temperature rise at respective surfaces. A new updated model for the chosen pump topology is created incorporating computational fluid dynamics with empirical fluid and heat transfer equations. This model represents the final geometry of the first generation prototype, incorporates eddy current heating, and has 60 discrete convection regions. Thermal analysis is performed at nominal and maximum flow rates, and temperature distributions are plotted. Results suggest that the pump will not exceed a temperature rise of 2 degrees C during normal operation.

Ad hoc cost analysis of the new gastrointestinal bleeding algorithm in patients with ventricular assist device.

PubMed

Hirose, Hitoshi; Sarosiek, Konrad; Cavarocchi, Nicholas C

2014-01-01

Gastrointestinal bleed (GIB) is a known complication in patients receiving nonpulsatile ventricular assist devices (VAD). Previously, we reported a new algorithm for the workup of GIB in VAD patients using deep bowel enteroscopy. In this new algorithm, patients underwent fewer procedures, received less transfusions, and took less time to make the diagnosis than the traditional GIB algorithm group. Concurrently, we reviewed the cost-effectiveness of this new algorithm compared with the traditional workup. The procedure charges for the diagnosis and treatment of each episode of GIB was ~ $2,902 in the new algorithm group versus ~ $9,013 in the traditional algorithm group (p < 0.0001). Following the new algorithm in VAD patients with GIB resulted in fewer transfusions and diagnostic tests while attaining a substantial cost savings per episode of bleeding.

Energy Exchange NASA Opening Plenary

NASA Technical Reports Server (NTRS)

Marrs, Rick

2017-01-01

Rick Marrs, Deputy Assistant Administrator Office of Strategic Infrastructure NASA Headquarters will be speaking during the 2017 Energy Exchange opening plenary. His presentation showcases the NASA mission, sustainability at NASA, NASA's strategic Sustainability Performance Plan, Existing PV Partnerships, and NASA funded Solar Initiatives at KSC.

Echocardiographic findings in stable outpatients with properly functioning HeartMate II left ventricular assist devices.

PubMed

Topilsky, Yan; Oh, Jae K; Atchison, Fawn W; Shah, Dipesh K; Bichara, Valentina M; Schirger, John A; Kushwaha, Sudhir S; Pereira, Naveen L; Park, Soon J

2011-02-01

Continuous-flow left ventricular assist devices (LVADs) have become part of the standard of care for the treatment of advanced heart failure. However, knowledge of normal values for transthoracic echocardiographic examination and measurements in these patients are lacking. All transthoracic echocardiographic examinations in 63 consecutive patients, performed 90 and 180 days after surgery with the implantation of a HeartMate II continuous-flow LVAD between February 2007 and January 2010, were retrospectively analyzed. All patients had to be outpatients at 3 and 6 months after surgery and considered stable on LVAD therapy (New York Heart Association class I or II and no need for inotropes, intravenous furosemide, or hospitalization). End-diastolic and end-systolic diameters and left ventricular mass decreased considerably compared with baseline measurements before LVAD implantation. Mitral inflow deceleration time increased (188 ± 70 vs 132.5 ± 27 msec, P = .009) and left atrial volume (84.1 ± 33 vs 141.7 ± 62 mL, P = .003) and E/e' ratio decreased (20.3 ± 9 vs 26 ± 11, P = .01), all consistent with decreased left ventricular filling pressure. Estimated right ventricular (RV) and right atrial pressure decreased significantly (34.1 ± 10 vs 51.7 ± 14 mm Hg and 9.5 ± 5 vs 14.4 ± 5 mm Hg, respectively, P < .0001 for both). Quantitatively estimated RV function (P = .02), RV fractional area change (27.9 ± 10% vs 37.4 ± 10.9%, P < .0001), and the RV index of myocardial performance (0.32 ± 0.1 vs 0.65 ± 0.2 vs 0.32 ± .01, P < .0001) improved, suggesting improved RV efficiency. LVAD therapy resulted in significant decreases in the severity of mitral regurgitation. Tricuspid regurgitation improved in patients who had concurrent tricuspid surgical correction and was unchanged otherwise. Aortic regurgitation severity increased 3 months after LVAD implantation. There were no significant differences in any of the echocardiographic parameters in the 6-month

Design, development, and first in vivo results of an implantable ventricular assist device, MicroVad.

PubMed

Kerkhoffs, Wolfgang; Schumacher, Oliver; Meyns, Bart; Verbeken, Erik; Leunens, Veerle; Bollen, Hilde; Reul, Helmut

2004-10-01

The design concept and first in vitro and in vivo results of a long-term implantable ventricular assist device system based on a microaxial blood pump are presented. The blood-immersed parts of the pump consist of a single-stage impeller and a proximally integrated microelectric motor. Both parts are surrounded by a pump housing currently made of polycarbonate to allow visible access to the blood-exposed parts. A titanium inflow cage attached to the tip of the housing is directly implanted into the left ventricular apex. The outflow of the pump is connected to the descending aorta by means of an e-PTFE graft. The overall dimensions of the device are 12 mm in outer diameter and about 50 mm in length. The calculated lifetime of the device is up to 2 years. The system underwent long-term durability tests, hydraulic performance tests, dynamic stability tests, and in vitro hemolysis and thrombogenicity tests. Furthermore, animal tests have been performed in adult Dorset sheep. In a first series, the pump has been placed extracorporeally; in a second series, the pump was completely implanted. Mean duration of the animal experiments of the second series was 31 days (range 8-110 days, n=14); no anticoagulation was administered over the whole test period. Blood data revealed no significant changes in blood cell counts, ionogram, or any other value. No end-organ dysfunction induced by long-term support could be observed, nor did the pathology reveal any evidence of thromboembolic complications.

A cloud-based home management system for patients with a left ventricular assist device: a case report.

PubMed

Nomoto, Shinichi; Utsumi, Momoe; Minakata, Kenji

2016-07-04

Since implantable left ventricular assist devices (LVAD) with smaller configurations became available for bridge-to-transplant or even destination therapy in patients with end-stage heart failure, an increasing number of patients with these devices are receiving home medical management. However, these patients may be anxious about potential complications such as pump failure, thromboembolism, and infections that may occur during home management. To provide a sense of security during home management of patients with LVAD and to establish an ideal shared-care system, we developed a patient-centered cloud-based home management system for patients with LVAD. In this case report, we describe this system and report a trial of it in a 64-year-old patient with an LVAD.

Successful continuous-flow left ventricular assist device implantation with adjuvant tricuspid valve repair for advanced heart failure.

PubMed

Lee, Chih-Hsien; Wei, Jeng

The prevalence of end-stage heart failure (HF) is on the increase, however, the availability of donor hearts remains limited. Left ventricular assist devices (LVADs) are increasingly being used for treating patients with end-stage HF. LVADs are not only used as a bridge to transplantation but also as a destination therapy. HeartMate II, a new-generation, continuous-flow LVAD (cf-LVAD), is currently an established treatment option for patients with HF. Technological progress and increasing implantation of cf-LVADs have significantly improved survival in patients with end-stage HF. Here we report a case of a patient with end-stage HF who was successfully supported using cf-LVAD implantation with adjuvant tricuspid valve repair in a general district hospital.

Left ventricular assist device therapy in patients with restrictive and hypertrophic cardiomyopathy.

PubMed

Topilsky, Yan; Pereira, Naveen L; Shah, Dipesh K; Boilson, Barry; Schirger, John A; Kushwaha, Sudhir S; Joyce, Lyle D; Park, Soon J

2011-05-01

Left ventricular assist device (LVAD) is being increasingly used in patients with end-stage dilated and ischemic cardiomyopathy. There have been no clinical trials addressing the use of LVAD therapy in patients with end-stage heart failure caused by restrictive (RCM) or hypertrophic cardiomyopathy (HCM). The purpose of this study was therefore to analyze the outcome of LVAD therapy in these patients. Eighty-three patients received continuous axial flow LVAD (Heart mate II, Thoratec, Pleasanton, CA) from February 2007 to May 2010 at our institution. We analyzed the baseline characteristics and surgical and long-term impact of LVAD therapy in 8 patients with RCM or HCM and compared their outcomes with the 75 patients with dilated and ischemic cardiomyopathy. Compared with patients with ischemic or dilated cardiomyopathy, patients with RCM and HCM have significantly smaller left ventricular end-diastolic dimensions (52.5±6 mm versus 68.6±8 mm; P<0.0001) and increased thickness of septal (16 [12, 19] mm versus 10[8.5, 11] mm, P=0.0003) and higher left ventricular ejection fraction (21 [20, 36]% versus 17 [15, 22]%; P=0.0009). We found no difference in early mortality (12.5% versus 9.3%, P=0.57) or length of hospital stay (11 [8, 45] days versus 18.5 [12.2, 27.7] days; P=0.51) between the 2 groups. The right atrial pressure was higher (18 [15, 20] mm Hg versus 12 [9, 15] mm Hg, P=0.03), and pump flow was lower (4.3 [3.8, 4.5] L versus 5.2 [4.7, 5.5] L, P=0.001) after LVAD implantation in patients with RCM and HCM. Central venous catheter related infections were more common in patients with RCM and HCM (87.5% versus 44.5%, P=0.006). There was no difference in the total number of blood units transfused. Median (min, max) follow-up duration after LVAD implantation was 166 [1, 1044] days. The 1-year actuarial survival rate was not different between the 2 groups (87.5% [95% confidence interval, 52.9% to 97.8%] versus 73.2 [95% confidence interval, 60% to 85%]; P=0.77). Our

AN INTRACORPOREAL (ABDOMINAL) LEFT VENTRICULAR ASSIST DEVICE [ALVAD], XXX: CLINICAL READINESS AND INITIAL TRIALS IN MAN

PubMed Central

Norman, John C.

1976-01-01

The purpose of this report is to present documenting evidence of the clinical readiness of an abdominal left ventricular assist device (ALVAD) according to NHLI criteria,‡ and the initiation of clinical trials of this device in otherwise irretrievable adult post-cardiotomy patients at the Texas Heart Institute of St. Luke's Episcopal and Texas Children's Hospitals. The ALVAD system has been developed, modified, and improved under NHLI auspices over the last eight years,‡‡ with annual reviews. Over 20,000 hours of in-vivo testing in the calf have been accomplished in our laboratories. The current clinical trials underwent two federal reviews (May 22, 1973 and October 17, 1974) and were the topic of an Ad Hoc Workshop at NHLI on October 28, 1973.‡‡‡ More recently, a consecutive series of 26 bovine ALVAD implantations were undertaken; acute and chronic hemodynamic effectiveness with maintenance or augmentation of the systemic circulation during profound ventricular unloading without undue blood trauma, intra-or extra-prosthetic thrombosis, or sepsis was demonstrated; no biomaterials problems were encountered. In-vivo realibility and durability, histologic and pathologic results were detailed, summarized, and submitted to NHLI. Patient acceptability surveys and geometric and volumetric human configuration studies were analyzed. Categorizations of the patients at risk in our institutions and the needs for such a device were documented. The periods of intended use (two weeks-one month), weaning procedures, and the possibility of pump dependence have been discussed. The legal, moral, ethical and informed consent issues were addressed. Clinical protocols (anesthesia, surgical, cardiologic, hematologic, engineering, computerized data-acquisition, follow-up) and cost analyses were developed. The device has now been used in four terminal patients since December, 1975; all subsequently succumbed, but their circulations were temporarily supported during total left

Von Willebrand factor, a versatile player in gastrointestinal bleeding in left ventricular assist device recipients?

PubMed

Fischer, Quentin; Huisse, Marie-Geneviève; Voiriot, Guillaume; Caron, Claudine; Lepage, Laurent; Dilly, Marie-Pierre; Nataf, Patrick; Ajzenberg, Nadine; Kirsch, Matthias

2015-01-01

Bleeding originating in the gastrointestinal (GI) tract is one of the most common adverse events after left ventricular assist device (LVAD) implantation. In these patients, GI bleeding appears to be the consequence of altered hemostasis on the one hand and alterations of the GI microvasculature on the other. We report the case of a patient who suffered repeated, severe GI bleeding early after implantation of a HeartMate II continuous-flow LVAD. After failure of conventional treatment strategies, GI bleeding was controlled using repeated transfusions of a purified von Willebrand factor (VWF) concentrate, almost devoid of Factor VIII (Wilfactin, LFB). No episodes of pump thrombosis were noted. Subsequent to VWF transfusions, we observed a progressive normalization of circulating vascular endothelial growth factor levels. Our data raise the possibility that, in addition to its hemostatic properties, transfusions of VWF might have acted as an antiangiogenic factor. © 2014 AABB.

Social Support Moderates the Relationship Between Perceived Stress and Quality of Life in Patients With a Left Ventricular Assist Device.

PubMed

Abshire, Martha; Russell, Stuart D; Davidson, Patricia M; Budhathoki, Chakra; Han, Hae-Ra; Grady, Kathleen L; Desai, Shashank; Dennison Himmelfarb, Cheryl

2018-04-20

Living with a left ventricular assist device has significant psychosocial sequelae that affect health-related quality of life (HRQOL). The purpose of this study was to (1) describe psychosocial indicators of stress including perceived stress, depression, fatigue, and coping; (2) examine relationships among stress indicators by level of perceived stress; (3) examine relationships among indicators of stress and clinical outcomes; and (4) test the moderation of social support on the relationship between stress and clinical outcomes. Participants were recruited from 2 outpatient clinics in a cross-sectional study design. Standardized measures were self-administered via survey. Descriptive statistics, correlation, and multiple linear regression analysis were conducted. The sample (N = 62) was mostly male (78%), black (47%), and married (66%), with a mean age of 56.5 ± 13 years. The overall sample had a moderate stress profile: moderate perceived stress (mean, 11.7 ± 7), few depressive symptoms (mean, 3.2 ± 3.9), and moderate fatigue (mean, 14.3 ± 9.1). Increased perceived stress was associated with fatigue, depressive symptoms, and maladaptive coping (P < .001). Regression analysis demonstrated that perceived stress and fatigue were significant correlates of overall HRQOL (adj. R = 0.41, P < .0001). Social support moderated the relationship between perceived stress and HRQOL, controlling for fatigue (R = 0.49, P < .001). Individuals living with left ventricular assist device with high perceived stress have worse depressive symptoms, fatigue, and coping. The influence of high social support to improve the relationship between stress and HRQOL underscores the importance of a comprehensive plan to address psychosocial factors.

Left Atrial Pressure Monitoring With an Implantable Wireless Pressure Sensor After Implantation of a Left Ventricular Assist Device

PubMed Central

Baranowski, Jacek; Delshad, Baz; Ahn, Henrik

2017-01-01

After implantation of a continuous-flow left ventricular assist device (LVAD), left atrial pressure (LAP) monitoring allows for the precise management of intravascular volume, inotropic therapy, and pump speed. In this case series of 4 LVAD recipients, we report the first clinical use of this wireless pressure sensor for the long-term monitoring of LAP during LVAD support. A wireless microelectromechanical system pressure sensor (Titan, ISS Inc., Ypsilanti, MI) was placed in the left atrium in four patients at the time of LVAD implantation. Titan sensor LAP was measured in all four patients on the intensive care unit and in three patients at home. Ramped speed tests were performed using LAP and echocardiography in three patients. The left ventricular end-diastolic diameter (cm), flow (L/min), power consumption (W), and blood pressure (mm Hg) were measured at each step. Measurements were performed over 36, 84, 137, and 180 days, respectively. The three discharged patients had equipment at home and were able to perform daily recordings. There were significant correlations between sensor pressure and pump speed, LV and LA size and pulmonary capillary wedge pressure, respectively (r = 0.92–0.99, p < 0.05). There was no device failure, and there were no adverse consequences of its use. PMID:27676410

Left ventricular assist device: exercise capacity evolution and rehabilitation added value.

PubMed

Lamotte, Michel X; Chimenti, Sara; Deboeck, Gael; Gillet, Alexis; Kacelenenbogen, Raymond; Strapart, Jonathan; Vandeneynde, Frédéric; Van Nooten, Guido; Antoine, Martine

2018-06-01

With more than 15,000 implanted patients worldwide and a survival rate of 80% at 1-year and 59% at 5-years, left ventricular assist device (LVAD) implantation has become an interesting strategy in the management of heart failure patients who are resistant to other kinds of treatment. There are limited data in the literature on the change over time of exercise capacity in LVAD patients, as well as limited knowledge about the beneficial effects that rehabilitation might have on these patients. Therefore, the aim of our study was to evaluate the evolution of exercise capacity on a cohort of patients implanted with the same device (HeartWare © ) and to analyse the potential impact of rehabilitation. Sixty-two patients implanted with a LVAD between June 2011 and June 2015 were screened. Exercise capacity was evaluated by cardiopulmonary exercise testing at 6 weeks, 6 and 12 months after implantation. We have observed significant differences in the exercise capacity and evolution between the trained and non-trained patients. Some of the trained patients nearly normalised their exercise capacity at the end of the rehabilitation programme. Exercise capacity of patient implanted with a HeartWare © LVAD increased in the early period after implantation. Rehabilitation allowed implanted patients to have a significantly better evolution compared to non-rehabilitated patients.

First World Report of Internal Power Cable Repair in Left Ventricular Assist Device Jarvik 2000: Case Report.

PubMed

Sassi, C G; Cameli, M; Dokollari, A; Diciolla, F; Scolletta, S; Ricci, C; Lucatelli, P; Mondillo, S; Maccherini, M

2017-05-01

There are limited clinical reports concerning internal power cable fixing in left ventricular assist device (L-VAD) patients. Actually there are no reports in the literature about Jarvik 2000 internal cable repair. We show the first description of a technique for surgical reparation of such a fatal complication. The patient was a 62-year-old woman who had L-VAD implantation (Jarvik 2000) with outflow graft apposition in descending thoracic aorta through left thoracotomy access, in 2009. She arrived urgently on January 25, 2014 for Jarvik 2000 dysfunction correlated with head movements. The neck X-rays revealed the rupture of one of the nine power cables located inside the neck and the damaging of two more cables nearby to be ruptured. On the same day she got pump failure due to the final interruption of the remaining two cables, we were obliged to install femoro-femoral extracorporeal membrane oxygenation (ECMO) assistance, to repair the power cables, approaching them through a pacemaker extension cable. The L-VAD outflow was occluded with vascular ball occluder inserted via right axillary artery under fluoroscopy before ECMO installation. At the end the ECMO assistance was interrupted and the Jarvik 2000 was turned back on. The patient was dismissed from the hospital 12 days after the procedure. At the moment the international literature is poor regarding this issue. This case provides evidence that in emergency conditions ECMO assistance is mandatory and a hybrid surgical and radiological approach could help to repair the damage in safe conditions. Copyright © 2017 Elsevier Inc. All rights reserved.

Developing an Anti-Xa-Based Anticoagulation Protocol for Patients with Percutaneous Ventricular Assist Devices.

PubMed

Sieg, Adam; Mardis, B Andrew; Mardis, Caitlin R; Huber, Michelle R; New, James P; Meadows, Holly B; Cook, Jennifer L; Toole, J Matthew; Uber, Walter E

2015-01-01

Because of the complexities associated with anticoagulation in temporary percutaneous ventricular assist device (pVAD) recipients, a lack of standardization exists in their management. This retrospective analysis evaluates current anticoagulation practices at a single center with the aim of identifying an optimal anticoagulation strategy and protocol. Patients were divided into two cohorts based on pVAD implanted (CentriMag (Thoratec; Pleasanton, CA) / TandemHeart (CardiacAssist; Pittsburgh, PA) or Impella (Abiomed, Danvers, MA)), with each group individually analyzed for bleeding and thrombotic complications. Patients in the CentriMag/TandemHeart cohort were subdivided based on the anticoagulation monitoring strategy (activated partial thromboplastin time (aPTT) or antifactor Xa unfractionated heparin (anti-Xa) values). In the CentriMag/TandemHeart cohort, there were five patients with anticoagulation titrated based on anti-Xa values; one patient developed a device thrombosis and a major bleed, whereas another patient experienced major bleeding. Eight patients received an Impella pVAD. Seven total major bleeds in three patients and no thrombotic events were detected. Based on distinct differences between the devices, anti-Xa values, and outcomes, two protocols were created to guide anticoagulation adjustments. However, anticoagulation in patients who require pVAD support is complex with constantly evolving anticoagulation goals. The ideal level of anticoagulation should be individually determined using several coagulation laboratory parameters in concert with hemodynamic changes in the patient's clinical status, the device, and the device cannulation.

Evolution of general surgical problems in patients with left ventricular assist devices.

PubMed

McKellar, Stephen H; Morris, David S; Mauermann, William J; Park, Soon J; Zietlow, Scott P

2012-11-01

Left ventricular assist devices (LVADs) are increasingly used to treat patients with end-stage heart failure. These patients may develop acute noncardiac surgical problems around the time of LVAD implantation or, as survival continues to improve, chronic surgical problems as ambulatory patients remote from the LVAD implant. Previous reports of noncardiac surgical problems in LVAD patients included patients with older, first-generation devices and do not address newer, second-generation devices. We describe the frequency and management of noncardiac surgical problems encountered during LVAD support with these newer-generation devices to assist noncardiac surgeons involved in the care of patients with LVADs. We retrospectively reviewed the medical records of consecutive patients receiving LVADs at our institution. We collected data for any consultation by noncardiac surgeons within the scope of general surgery during LVAD support and subsequent treatment. Ninety-nine patients received implantable LVADs between 2003 and 2009 (first-generation, n = 19; second-generation, n = 80). Excluding intestinal hemorrhage, general surgical opinions were rendered for 34 patients with 49 problems, mostly in the acute recovery phase after LVAD implantation. Of those, 27 patients underwent 28 operations. Respiratory failure and intra-abdominal pathologies were the most common problems addressed, and LVAD rarely precluded operation. Patients with second-generation LVADs were more likely to survive hospitalization (P = .04) and develop chronic, rather than emergent, surgical problems. Patients with LVADs frequently require consultation from noncardiac surgeons within the scope of general surgeons and often require operation. Patients with second-generation LVADs are more likely to become outpatients and develop more elective surgical problems. Noncardiac surgeons will be increasingly involved in caring for patients with LVADs and should anticipate the problems unique to this patient

NASA New England Outreach Center

NASA Technical Reports Server (NTRS)

2002-01-01

The NASA New England Outreach Center in Nashua, New Hampshire was established to serve as a catalyst for heightening regional business awareness of NASA procurement, technology and commercialization opportunities. Emphasis is placed on small business participation, with the highest priority given to small disadvantaged businesses, women-owned businesses, HUBZone businesses, service disabled veteran owned businesses, and historically black colleges and universities and minority institutions. The Center assists firms and organizations to understand NASA requirements and to develop strategies to capture NASA related procurement and technology opportunities. The establishment of the NASA Outreach Center serves to stimulate business in a historically underserved area. NASA direct business awards have traditionally been highly present in the West, Midwest, South, and Southeast areas of the United States. The Center guides and assists businesses and organizations in the northeast to target opportunities within NASA and its prime contractors and capture business and technology opportunities. The Center employs an array of technology access, one-on-one meetings, seminars, site visits, and targeted conferences to acquaint Northeast firms and organizations with representatives from NASA and its prime contractors to learn about and discuss opportunities to do business and access the inventory of NASA technology. This stimulus of interaction also provides firms and organizations the opportunity to propose the use of their developed technology and ideas for current and future requirements at NASA. The Center provides a complement to the NASA Northeast Regional Technology Transfer Center in developing prospects for commercialization of NASA technology. In addition, the Center responds to local requests for assistance and NASA material and documents, and is available to address immediate concerns and needs in assessing opportunities, timely support to interact with NASA Centers on

Development of an Inlet Pressure Sensor for Control in a Left Ventricular Assist Device

PubMed Central

Fritz, Bryan; Cysyk, Joshua; Newswanger, Ray; Weiss, William; Rosenberg, Gerson

2010-01-01

A Tesla type continuous flow left ventricular assist device (VAD) has been designed by Penn State and Advanced Bionics, Inc. (ABI). When a continuous flow device is employed, care must be taken to limit low pressures in the ventricle that can produce an obstruction to the inlet cannula or trigger arrhythmias. Design of an inexpensive, semi-conductor strain gage inlet pressure sensor to detect suction has been completed. The research and design analysis included finite element modeling of the sensing region. Sensitivity, step-response, temperature dependence and hysteresis tests have been performed on prototype units. All sensors were able to withstand the maximum expected strain of 82 μin/in at 500 mmHg internal pressure. Average sensitivity was 0.52 ±0.24 μV/mmHg with 0.5 V excitation (n=5 units). Step response time for a 0 to 90 mmHg step change averaged 22 milliseconds. Hysteresis was measured by applying and holding 75mmHg internal pressure for 4 hours, followed by a zero pressure measurement, and ranged from -15 mmHg to 4.1 mmHg (n=3 units). Offset drift varied between 180 and -140 mmHg over a four week period. (n=2 units). Span temperature sensitivity ranged from 18 to -21 μV/°C (n=5 units). Gain temperature sensitivity ranged from -7.4 to 4.9 μV/°C (n=5 units). With the inherent drift, it is currently not possible to use the transducer to measure actual pressures, but it can easily be used to measure pressure changes throughout the cardiac cycle. This signal can then be used in the control system to avoid ventricular suction events. PMID:20335797

B-type natriuretic peptide levels and continuous-flow left ventricular assist devices.

PubMed

Sareyyupoglu, Basar; Boilson, Barry A; Durham, Lucian A; McGregor, Christopher G A; Daly, Richard C; Redfield, Margaret M; Edwards, Brooks S; Frantz, Robert P; Pereira, Naveen L; Park, Soon J

2010-01-01

We postulated that postoperative B-type natriuretic peptide (BNP) levels would be reflective of the degree of hemodynamic support rendered by various pump speeds settings (RPM) of continuous-flow left ventricular assist devices (LVADs). Twenty LVAD patients were evaluated prospectively (Jarvik 2000: n = 9, HeartMate II: n = 11). The mean age was 57.7 ± 14.9 years, and 14 were male. B-type natriuretic peptide levels were drawn while the patients were supported on LVADs at variable RPM settings. The RPM settings were correlated with the changes in BNP levels. Eleven patients underwent LVAD implantation for a lifelong support while the rest were as a bridge therapy to transplantation. Four patients required LVAD change out for various causes of pump failure. Postoperative BNP levels decreased dramatically with the initiation of LVAD support. The levels correlated inversely with the degree of hemodynamic support rendered at various RPM settings of the HeartMate II (p < 0.001). Overall, BNP levels decreased significantly in 2 days after RPM increase. We observed a significant inverse correlation between the postoperative BNP levels and the degree of LVAD support. The effective LVAD support seems to result in a marked reduction in BNP levels, and monitoring serial BNP levels may be helpful in managing patients supported on continuous LVAD.

Chronic ovine evaluation of a totally implantable electrical left ventricular assist system.

PubMed

Ramasamy, N; Chen, H; Miller, P J; Jassawalla, J S; Greene, B A; Ocampo, A; Siegel, L C; Oyer, P E; Portner, P M

1989-01-01

The totally implantable Novacor left ventricular assist system (LVAS) comprises a pump/drive unit (VAD), electronic control and power subsystem (ECP), variable volume compensator (VVC), and belt skin transformer (BST). The system is now undergoing chronic in vivo evaluation. Cumulative animal testing of VAD, VVC, and BST subsystems are 12.1, 4.9, and 43 years, respectively. The longest implants were 279 days for the VAD, 767 days for the VVC, and 1,148 days for the BST. A chronic implant of the total system was electively terminated at 260 days. The LVAS was powered via the BST. Continuously monitored hemodynamic and pump parameters have demonstrated normal hemodynamics and LVAS operation. Periodic VVC determinations suggest a 0.8 ml/day diffusive gas loss. Tether-free operation has been demonstrated with an Ag-Zn battery backpack. The animal was healthy and free of infection as indicated by routine hematologic, biochemical and serum enzyme determinations. Hemolysis is minimal (plasma free hemoglobin less than 5 mg%). Pump output ranged from 7 to 8 L/min. Severe valve calcification was the reason for elective termination at 260 days. This preclinical in vivo experience, and in vitro reliability studies, demonstrate efficacy of the total system.

Renal Function Changes Following Left Ventricular Assist Device Implantation.

PubMed

Daimee, Usama A; Wang, Meng; Papernov, Anna; Sherazi, Saadia; McNitt, Scott; Vidula, Himabindu; Chen, Leway; Alexis, Jeffrey D; Kutyifa, Valentina

2017-12-15

Limited data assessing the clinical significance of post-left ventricular assist device (LVAD) in renal function are available. We aimed to investigate the impact of changes in renal function after LVAD implantation on subsequent long-term outcomes. We followed 184 patients with HeartMate II LVADs implanted between May 2008 and November 2014. Serial assessment of renal function, was performed at baseline and at day 1, day 7, 1 month, 3 months, 6 months, 1 year, and 2 years after implantation. Effects of 1-month GFR and changes in GFR from baseline to 1 month on long-term mortality and hospital re-admission were evaluated. There were 30 patients with GFR <45 (low), 44 with GFR 45 to 59 (intermediate), and 110 with GFR ≥60 (normal) at baseline. Only patients with baseline GFR <45 experienced significant improvement in GFR after 2 years of follow-up (p = 0.012). At 1 month, a higher GFR category was significantly associated with a 31% reduction in mortality (hazard ratio [HR] 0.69, CI 0.49 to 0.98, p = 0.036), but not re-admission. Patients with baseline low and intermediate GFR who had no improvement in renal function category at 1 month experienced significantly greater risk of mortality (HR 1.95, CI 1.10 to 3.43, p = 0.022) and re-admission (HR 1.75, CI 1.07 to 2.84, p = 0.025), relative to patients whose GFR was normal at baseline and 1 month. In conclusion, renal function after LVAD implantation improves in patients with GFR <45. Change in renal function from baseline to 1 month after implantation is a powerful marker of long-term outcomes. Copyright © 2017 Elsevier Inc. All rights reserved.

The Influence of Different Operating Conditions on the Blood Damage of a Pulsatile Ventricular Assist Device.

PubMed

Xu, Zihao; Yang, Ming; Wang, Xianghui; Wang, Zhong

2015-01-01

Because of pulsatile blood flow's benefit for myocardial recovery, perfusion of coronary arteries and end organs, pulsatile ventricular assist devices (VADs) are still widely used as paracorporeal mechanical circulatory support devices in clinical applications, especially in pediatric heart failure patients. However, severe blood damage limits the VAD's service period. Besides optimizing the VAD geometry to reduce blood damage, the blood damage may also be decreased by changing the operating conditions. In this article, a pulsatile VAD was used to investigate the influence of operating conditions on its blood damage, including hemolysis, platelet activation, and platelet deposition. Three motion profiles of pusher plate (sine, cosine, and polynomial), three stroke volumes (ejection fractions) (56 ml [70%], 42 ml [52.5%], and 28 ml [35%]), three pulsatile rates (75, 100, and 150 bpm), and two assist modes (copulsation and counterpulsation) were implemented respectively in VAD fluid-structure interaction simulations to calculate blood damage. The blood damage indices indicate that cosine motion profile, higher ejection fraction, higher pulsatile rate, and counterpulsation can decrease platelet deposition whereas increase hemolysis and platelet activation, and vice versa. The results suggest that different operating conditions have different effects on pulsatile VAD's blood damage and may be beneficial to choose suitable operating condition to reduce blood damage in clinical applications.

Singularity now: using the ventricular assist device as a model for future human-robotic physiology.

PubMed

Martin, Archer K

2016-04-01

In our 21 st century world, human-robotic interactions are far more complicated than Asimov predicted in 1942. The future of human-robotic interactions includes human-robotic machine hybrids with an integrated physiology, working together to achieve an enhanced level of baseline human physiological performance. This achievement can be described as a biological Singularity. I argue that this time of Singularity cannot be met by current biological technologies, and that human-robotic physiology must be integrated for the Singularity to occur. In order to conquer the challenges we face regarding human-robotic physiology, we first need to identify a working model in today's world. Once identified, this model can form the basis for the study, creation, expansion, and optimization of human-robotic hybrid physiology. In this paper, I present and defend the line of argument that currently this kind of model (proposed to be named "IshBot") can best be studied in ventricular assist devices - VAD.

Singularity now: using the ventricular assist device as a model for future human-robotic physiology

PubMed Central

Martin, Archer K.

2016-01-01

In our 21st century world, human-robotic interactions are far more complicated than Asimov predicted in 1942. The future of human-robotic interactions includes human-robotic machine hybrids with an integrated physiology, working together to achieve an enhanced level of baseline human physiological performance. This achievement can be described as a biological Singularity. I argue that this time of Singularity cannot be met by current biological technologies, and that human-robotic physiology must be integrated for the Singularity to occur. In order to conquer the challenges we face regarding human-robotic physiology, we first need to identify a working model in today’s world. Once identified, this model can form the basis for the study, creation, expansion, and optimization of human-robotic hybrid physiology. In this paper, I present and defend the line of argument that currently this kind of model (proposed to be named “IshBot”) can best be studied in ventricular assist devices – VAD. PMID:28913480

Optimal pressure regulation of the pneumatic ventricular assist device with bellows-type driver.

PubMed

Lee, Jung Joo; Kim, Bum Soo; Choi, Jaesoon; Choi, Hyuk; Ahn, Chi Bum; Nam, Kyoung Won; Jeong, Gi Seok; Lim, Choon Hak; Son, Ho Sung; Sun, Kyung

2009-08-01

The bellows-type pneumatic ventricular assist device (VAD) generates pneumatic pressure with compression of bellows instead of using an air compressor. This VAD driver has a small volume that is suitable for portable devices. However, improper pneumatic pressure setup can not only cause a lack of adequate flow generation, but also cause durability problems. In this study, a pneumatic pressure regulation system for optimal operation of the bellows-type VAD has been developed. The optimal pneumatic pressure conditions according to various afterload conditions aiming for optimal flow rates were investigated, and an afterload estimation algorithm was developed. The developed regulation system, which consists of a pressure sensor and a two-way solenoid valve, estimates the current afterload and regulates the pneumatic pressure to the optimal point for the current afterload condition. Experiments were performed in a mock circulation system. The afterload estimation algorithm showed sufficient performance with the standard deviation of error, 8.8 mm Hg. The flow rate could be stably regulated with a developed system under various afterload conditions. The shortcoming of a bellows-type VAD could be handled with this simple pressure regulation system.

Echocardiographic variables after left ventricular assist device implantation associated with adverse outcome.

PubMed

Topilsky, Yan; Hasin, Tal; Oh, Jae K; Borgeson, Daniel D; Boilson, Barry A; Schirger, John A; Clavell, Alfredo L; Frantz, Robert P; Tsutsui, Rayji; Liu, Mingya; Maltais, Simon; Kushwaha, Sudhir S; Pereira, Naveen L; Park, Soon J

2011-11-01

Operative mortality after left ventricular assist device (LVAD) implantation is heavily influenced by patient selection and the technical difficulty of surgery. However, how we treat our patients and LVAD setting may affect the patient outcome beyond this period. We postulated that the presence of echocardiographic variables 1 month after surgery suggesting appropriate degree of LV unloading and an adequate forward flow would be important in determining clinical outcomes after the initial successful LVAD implantation. We retrospectively analyzed various variables in echocardiographic examinations performed 30 days after LVAD implant in 76 consecutive patients receiving continuous flow device for their association with a compound end point (90-day mortality, readmission for heart failure, or New York Heart Association class III or higher at the end of the 90-day period). The echocardiographic associations examined included estimated LVAD flow, with and without native LV contribution, interventricular septal position, the status of aortic valve opening, an estimated left atrial pressure (ELAP), the mitral flow E-wave deceleration time, and the ratio of deceleration time to E-wave velocity (mitral deceleration index [MDI]). Four patients died during the 30- to 90-day period, 6 patients were readmitted for heart failure, and 25 patients were considered to have New York Heart Association class III or higher at the end of the 90-day period. Variables associated with adverse outcome included increased ELAP (odds ratio, 1.30 [1.16-1.48]; P<0.0001), MDI <2 ms/[cm/s] (odds ratio, 4.4 implantation [1.22-18]; P=0.02) and decreased tricuspid lateral annulus velocity (odds ratio, 0.70 implantation [0.48-0.95]; P=0.02). A leftward deviation of interventricular septum was associated with a worse outcome (odds ratio, 3.03 implantation [1.21-13.3]; P=0.01). Mortality and heart failure after LVAD surgery appear to be predominantly determined by echocardiographic evidence of

A left ventricular epicardial to right ventricular endocardial dominant frequency gradient exists in human ventricular fibrillation.

PubMed

Torres, Jose Luis; Shah, Bindi K; Greenberg, Richard M; Deger, Florin Titus; Gerstenfeld, Edward P

2010-10-01

We hypothesized that in patients with left ventricular dysfunction undergoing implant of a biventricular ICD, the local dominant frequency during early induced ventricular fibrillation would be higher at an epicardial left ventricular position compared to an endocardial right ventricular position. Patients undergoing implant of a biventricular ICD were studied. During ventricular fibrillation induction, bipolar electrograms were recorded from leads at an epicardial left ventricular position and an endocardial right ventricular position. Overlapping 2-s fast Fourier transforms were obtained for 6 s of ventricular fibrillation. The dominant frequency and organizational index were compared. Thirty-four patients (20 men, age 64 ± 11 years) underwent 57 inductions of ventricular fibrillation. Eighteen patients had non-ischemic dilated cardiomyopathy and 16 had ischemic dilated cardiomyopathy. The dominant frequency was higher at a lateral epicardial left ventricular position than an apical endocardial right ventricular position in 18 patients with non-ischemic dilated cardiomyopathy (LV epicardial 5.34 ± 0.37 Hz, RV endocardial 5.09 ± 0.41 Hz, p < 0.001), but not in 16 patients with ischemic dilated cardiomyopathy (LV epicardial 4.99 ± 0.57 Hz, RV epicardial 4.87 ± 0.65 Hz, p = 0.094). In patients with non-ischemic dilated cardiomyopathy, there is a dominant frequency gradient during early ventricular fibrillation induced at ICD testing from the lateral left ventricular epicardium to the apical right ventricular endocardium.

Early feasibility evaluation of thoracoscopically assisted transcatheter ventricular reconstruction in an experimental model of ischaemic heart failure with left anteroapical aneurysm.

PubMed

Cheng, Yanping; Yi, Geng-Hua; Annest, Lon S; Van Bladel, Kevin; Brown, Ryan; Wechsler, Andrew; Shibuya, Masahiko; Conditt, Gerard B; Peppas, Athanasios; Kaluza, Greg L; Granada, Juan F

2015-04-01

To test the feasibility of a thoracoscopically assisted, off-pump, transcatheter ventricular reconstruction (TCVR) approach in an ovine model of left ventricular (LV) anteroapical aneurysm. Myocardial infarction (MI) was induced by coil occlusion of the middle left anterior descending artery and diagonals. Two months after MI creation, TCVR was performed via a minimal thoracotomy in eight sheep. Under endoscopic and fluoroscopic guidance, trans-interventricular septal puncture was performed from the LV epicardial scar. A guidewire was externalised via a snare placed in the right ventricle from the external jugular vein. An internal anchor was inserted over the wire and positioned on the right ventricular septum and an external anchor was deployed on the LV anterior epicardium. Serial pairs of anchors were placed and plicated together to exclude the scar completely. Immediately after TCVR, echocardiography showed LV end-systolic volume decreased from pre-procedure 58.8±16.6 ml to 25.1±7.6 ml (p<0.01) and the ejection fraction increased from 32.0±7.3% to 52.0±7.5% (p<0.01). LV twist significantly improved (3.83±2.21 vs. pre-procedure -0.41±0.94, p=0.01) and the global peak-systolic longitudinal strain increased from -5.64% to -10.77% (p<0.05). TCVR using minimally invasive access techniques on the off-pump beating heart is feasible and resulted in significant improvement in LV performance.

Ventricular assist devices: a review of psychosocial risk factors and their impact on outcomes.

PubMed

Bruce, Courtenay R; Delgado, Estevan; Kostick, Kristin; Grogan, Sherry; Ashrith, Guha; Trachtenberg, Barry; Estep, Jerry D; Bhimaraj, Arvind; Pham, Linda; Blumenthal-Barby, Jennifer S

2014-12-01

Psychosocial contraindications for ventricular assist devices (VADs) remain particularly nebulous and are driven by institution-specific practices. Our multi-institutional, multidisciplinary workgroup conducted a review with the goal of addressing the following research question: How are preoperative psychosocial domains predictive of or associated with postoperative VAD-related outcomes? Answers to this question could contribute to the development of treatment-specific (contra) indications for patients under consideration for mechanical devices. We identified 5 studies that examined psychosocial factors and their relationship to postoperative VAD-related outcomes. Our results suggest that 3 psychosocial variables are possibly associated with VAD-related outcomes: depression, functional status, and self-care. Of the few studies that exist, the generalizability of findings is constrained by a lack of methodologic rigor, inconsistent terminology, and a lack of conceptual clarity. This review should serve as a call for research. Efforts to minimize psychosocial risk before device placement can only be successful insofar as VAD programs can clearly identify who is at risk for suboptimal outcomes. Copyright © 2014 Elsevier Inc. All rights reserved.

Can the Seattle heart failure model be used to risk-stratify heart failure patients for potential left ventricular assist device therapy?

PubMed

Levy, Wayne C; Mozaffarian, Dariush; Linker, David T; Farrar, David J; Miller, Leslie W

2009-03-01

According to results of the REMATCH trial, left ventricular assist device therapy in patients with severe heart failure has resulted in a 48% reduction in mortality. A decision tool will be necessary to aid in the selection of patients for destination left ventricular assist devices (LVADs) as the technology progresses for implantation in ambulatory Stage D heart failure patients. The purpose of this analysis was to determine whether the Seattle Heart Failure Model (SHFM) can be used to risk-stratify heart failure patients for potential LVAD therapy. The SHFM was applied to REMATCH patients with the prospective addition of inotropic agents and intra-aortic balloon pump (IABP) +/- ventilator. The SHFM was highly predictive of survival (p = 0.0004). One-year SHFM-predicted survival was similar to actual survival for both the REMATCH medical (30% vs 28%) and LVAD (49% vs 52%) groups. The estimated 1-year survival with medical therapy for patients in REMATCH was 30 +/- 21%, but with a range of 0% to 74%. The 1- and 2-year estimated survival was

The Ventricular Assist Device in the Life of the Child: A Phenomenological Pediatric Study.

PubMed

van Manen, Michael A

2017-05-01

What is it like for a child to live with an artificial heart? The use of some medical therapies in children requires developmental considerations, is associated with psychosocial consequences, and calls for ethical sensitivities. A critical case is the ventricular assist device (VAD), a mechanical pump used to support the functioning of a failing heart. As a pediatric therapy, the device can be used as a temporary solution for poor heart function, a bridge to transplantation or recovery, or as a destination therapy. While the mechanical-technical operation of the VAD is well understood, the clinical-technical aspects of young people living with this device are largely unexplored. Drawing on interviews of school-aged children, the aim of this phenomenological study is to explore how a VAD may structure or condition a child's meaningful experience of their world outside the hospital. The driveline of an implanted VAD is the peripheral attachment, extruding through the skin to connect the controller-power supply. The materiality of the device may be interruptive, restrictive, and disturbing to the psycho-physical being and sense of self-identity of the child as a child. And while a child equipped with a VAD is not necessarily conspicuous among other children, the child may experience the device as an exposing presence, while living with the worry of a caregiver who takes on the role not simply of parent but of watchful health professional. A phenomenological understanding of the VAD should assist parents and caregiving health professionals knowing how to deal with specific issues arising in the life of the VAD child.

Left ventricular function in Friedreich's ataxia. An echocardiographic study.

PubMed Central

Sutton, M G; Olukotun, A Y; Tajik, A J; Lovett, J L; Giuliani, E R

1980-01-01

Left ventricular function was assessed in seven patients with Friedreich's ataxia using computer-assisted analysis of the left ventricular echocardiograms and compared with those of 45 normal children matched for age and sex. The left ventricle in Friedreich's ataxia was symmetrically hypertrophied, cavity dimension was normal or small, and septal motion and peak velocity of circumferential shortening were normal in all patients. In diastole the duration of rapid filling was normal, peak rate of increase in left ventricular dimension was reduced in two patients, mitral valve opening was delayed with respect to minimum cavity dimension in seven, and there were significantly greater than normal increases in left ventricular dimension during the isovolumic period to mitral valve opening in seven, indicating abnormal and incoordinate relaxation. Peak rates of posterior wall systolic thickening and diastolic thinning were reduced in four and six patients, respectively, whereas peak rates of septal systolic thickening and diastolic thinning were reduced in one and four, respectively, suggesting a disproportionately greater impairment of the posterior wall than of septal function. The absence of asymmetric septal hypertrophy and mid-systolic closure of the aortic valve, the presence of normal septal motion, and the greater reduction in posterior wall than in septal dynamics are inconsistent with previous ideas that the heart disease of Friedreich's ataxia is identical to hypertrophic cardiomyopathy. Computer-assisted analysis of echocardiograms permits recognition of heart disease in Friedreich's ataxia before the onset of cardiac symptoms or development of clinical signs of heart disease. Images PMID:7426188

Left ventricular assist device exchange: the Toronto General Hospital experience.

PubMed

Tsubota, Hideki; Ribeiro, Roberto V P; Billia, Filio; Cusimano, Robert J; Yau, Terrence M; Badiwala, Mitesh V; Stansfield, William E; Rao, Vivek

2017-08-01

As support times for left ventricular assist devices (LVADs) become longer, several complications requiring device exchange may occur. To our knowledge, this is the first Canadian report regarding implantable LVAD exchange. We retrospectively reviewed the cases of consecutive, unique patients implanted with an LVAD between June 2006 and October 2015 at Toronto General Hospital. In total, 122 patients were impanted with an LVAD during the study period. Eight patients required LVAD exchange, and 1 patient had 2 replacements (9 of 122, 7.3%). There were 7 HeartMate II (HMII), 1 HVAD and 1 DuraHeart pumps exchanged. Two of these exchanges occurred early at the time of initial implant, whereas 7 occurred late (range 8-623 d). Six exchanges were made owing to pump thrombosis. Of the 3 exchanges made for other causes, 1 HMII exchange was owing to a driveline fracture, 1 DuraHeart patient had early inflow obstruction requiring exchange to HMII at the initial implant, and the third had a suspected inflow obstruction with no evidence of thrombosis at the time of the procedure. The mean support time before exchange was 225 days, and time from exchange to transplant, death or ongoing support was 245 days. Three patients were successfully bridged to transplant, and at the time of data collection 2 were supported awaiting transplant. Three patients died after a mean duration of 394.3 days (range 78-673 d) of support postreplacement. Four cases were successfully performed using a subcostal approach. Pump thrombosis is the most common cause for LVAD exchange, which can be performed with acceptable morbidity and mortality. The subcostal approach may be the preferred procedure for an HMII exchange when indicated.

Right ventricular dysfunction affects survival after surgical left ventricular restoration.

PubMed

Couperus, Lotte E; Delgado, Victoria; Palmen, Meindert; van Vessem, Marieke E; Braun, Jerry; Fiocco, Marta; Tops, Laurens F; Verwey, Harriëtte F; Klautz, Robert J M; Schalij, Martin J; Beeres, Saskia L M A

2017-04-01

Several clinical and left ventricular parameters have been associated with prognosis after surgical left ventricular restoration in patients with ischemic heart failure. The aim of this study was to determine the prognostic value of right ventricular function. A total of 139 patients with ischemic heart failure (62 ± 10 years; 79% were male; left ventricular ejection fraction 27% ± 7%) underwent surgical left ventricular restoration. Biventricular function was assessed with echocardiography before surgery. The independent association between all-cause mortality and right ventricular fractional area change, tricuspid annular plane systolic excursion, and right ventricular longitudinal peak systolic strain was assessed. The additive effect of multiple impaired right ventricular parameters on mortality also was assessed. Baseline right ventricular fractional area change was 42% ± 9%, tricuspid annular plane systolic excursion was 18 ± 3 mm, and right ventricular longitudinal peak systolic strain was -24% ± 7%. Within 30 days after surgery, 15 patients died. Right ventricular fractional area change (hazard ratio, 0.93; 95% confidence interval, 0.88-0.98; P < .01), tricuspid annular plane systolic excursion (hazard ratio, 0.80; 95% confidence interval, 0.66-0.96; P = .02), and right ventricular longitudinal peak systolic strain (hazard ratio, 1.15; 95% confidence interval, 1.05-1.26; P < .01) were independently associated with 30-day mortality, after adjusting for left ventricular ejection fraction and aortic crossclamping time. Right ventricular function was impaired in 21%, 20%, and 27% of patients on the basis of right ventricular fractional area change, tricuspid annular plane systolic excursion, and right ventricular longitudinal peak systolic strain, respectively. Any echocardiographic parameter of right ventricular dysfunction was present in 39% of patients. The coexistence of several impaired right ventricular parameters per patient was

Chronic In Vivo Testing of the Penn State Infant Ventricular Assist Device

PubMed Central

Weiss, William J.; Carney, Elizabeth L.; Clark, J. Brian; Peterson, Rebecca; Cooper, Timothy K.; Nifong, Thomas P.; Siedlecki, Christopher A; Hicks, Dennis; Doxtater, Bradley; Lukic, Branka; Yeager, Eric; Reibson, John; Cysyk, Joshua; Rosenberg, Gerson; Pierce, William S.

2011-01-01

The Penn State Infant Ventricular Assist Device is a 12-14 ml stroke volume pneumatically actuated pump, with custom Björk-Shiley monostrut valves, developed under the National Heart, Lung, and Blood Institute (NHLBI) Pediatric Circulatory Support program. In this report we describe the 7 most recent chronic animal studies of the Infant VAD in the juvenile ovine model, with a mean body weight of 23.5 +/- 4.1 kg. The goal of 4-6 weeks survival was achieved in 5 of 7 studies, with support duration ranging from 5 to 41 days; mean 26.1 days. Anticoagulation was accomplished using unfractionated heparin, and study animals were divided into 2 protocol groups: the first based on a target activated partial thromboplastin time of 1.5 to 2 times normal, and a second group using a target thromboelastography R-time of 2 times normal. The second group required significantly less heparin, which was verified by barely detectable heparin activity (anti-Xa). In both groups, there was no evidence of thromboembolism except in one animal with a chronic infection and fever. Device thrombi were minimal, and were further reduced by introduction of the custom valve. These results are consistent with results of adult VAD testing in animals, and are encouraging given the extremely low levels of anticoagulation in the second group. PMID:22157073

SdrF, a Staphylococcus epidermidis Surface Protein, Contributes to the Initiation of Ventricular Assist Device Driveline–Related Infections

PubMed Central

Arrecubieta, Carlos; Toba, Faustino A.; von Bayern, Manuel; Akashi, Hirokazu; Deng, Mario C.; Naka, Yoshifumi; Lowy, Franklin D.

2009-01-01

Staphylococcus epidermidis remains the predominant pathogen in prosthetic-device infections. Ventricular assist devices, a recently developed form of therapy for end-stage congestive heart failure, have had considerable success. However, infections, most often caused by Staphylococcus epidermidis, have limited their long-term use. The transcutaneous driveline entry site acts as a potential portal of entry for bacteria, allowing development of either localized or systemic infections. A novel in vitro binding assay using explanted drivelines obtained from patients undergoing transplantation and a heterologous lactococcal system of surface protein expression were used to identify S. epidermidis surface components involved in the pathogenesis of driveline infections. Of the four components tested, SdrF, SdrG, PIA, and GehD, SdrF was identified as the primary ligand. SdrF adherence was mediated via its B domain attaching to host collagen deposited on the surface of the driveline. Antibodies directed against SdrF reduced adherence of S. epidermidis to the drivelines. SdrF was also found to adhere with high affinity to Dacron, the hydrophobic polymeric outer surface of drivelines. Solid phase binding assays showed that SdrF was also able to adhere to other hydrophobic artificial materials such as polystyrene. A murine model of infection was developed and used to test the role of SdrF during in vivo driveline infection. SdrF alone was able to mediate bacterial adherence to implanted drivelines. Anti-SdrF antibodies reduced S. epidermidis colonization of implanted drivelines. SdrF appears to play a key role in the initiation of ventricular assist device driveline infections caused by S. epidermidis. This pluripotential adherence capacity provides a potential pathway to infection with SdrF-positive commensal staphylococci first adhering to the external Dacron-coated driveline at the transcutaneous entry site, then spreading along the collagen-coated internal portion of the

Performance of Noninvasive Assessment in the Diagnosis of Right Heart Failure After Left Ventricular Assist Device.

PubMed

Joly, Joanna M; El-Dabh, Ashraf; Marshell, Ramey; Chatterjee, Arka; Smith, Michelle G; Tresler, Margaret; Kirklin, James K; Acharya, Deepak; Rajapreyar, Indranee N; Tallaj, José A; Pamboukian, Salpy V

2018-06-01

Right heart failure (RHF) after left ventricular assist device (LVAD) is associated with poor outcomes. Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) defines RHF as elevated right atrial pressure (RAP) plus venous congestion. The purpose of this study was to examine the diagnostic performance of the noninvasive INTERMACS criteria using RAP as the gold standard. We analyzed 108 patients with LVAD who underwent 341 right heart catheterizations (RHC) between January 1, 2006, and December 31, 2013. Physical exam, echocardiography, and laboratory data at the time of RHC were collected. Conventional two-by-two tables were used and missing data were excluded. The noninvasive INTERMACS definition of RHF is 32% sensitive (95% CI, 0.21-0.44) and 97% specific (95% CI, 0.95-0.99) for identifying elevated RAP. Clinical assessment failed to identify two-thirds of LVAD patients with RAP > 16 mm Hg. More than half of patients with elevated RAP did not have venous congestion, which may represent a physiologic opportunity to mitigate the progression of disease before end-organ damage occurs. One-quarter of patients who met the noninvasive definition of RHF did not actually have elevated RAP, potentially exposing patients to unnecessary therapies. In practice, if any component of the INTERMACS definition is present or equivocal, our data suggest RHC is warranted to establish the diagnosis.

High fidelity computational simulation of thrombus formation in Thoratec HeartMate II continuous flow ventricular assist device

PubMed Central

Wu, Wei-Tao; Yang, Fang; Wu, Jingchun; Aubry, Nadine; Massoudi, Mehrdad; Antaki, James F.

2016-01-01

Continuous flow ventricular assist devices (cfVADs) provide a life-saving therapy for severe heart failure. However, in recent years, the incidence of device-related thrombosis (resulting in stroke, device-exchange surgery or premature death) has been increasing dramatically, which has alarmed both the medical community and the FDA. The objective of this study was to gain improved understanding of the initiation and progression of thrombosis in one of the most commonly used cfVADs, the Thoratec HeartMate II. A computational fluid dynamics simulation (CFD) was performed using our recently updated mathematical model of thrombosis. The patterns of deposition predicted by simulation agreed well with clinical observations. Furthermore, thrombus accumulation was found to increase with decreased flow rate, and can be completely suppressed by the application of anticoagulants and/or improvement of surface chemistry. To our knowledge, this is the first simulation to explicitly model the processes of platelet deposition and thrombus growth in a continuous flow blood pump and thereby replicate patterns of deposition observed clinically. The use of this simulation tool over a range of hemodynamic, hematological, and anticoagulation conditions could assist physicians to personalize clinical management to mitigate the risk of thrombosis. It may also contribute to the design of future VADs that are less thrombogenic. PMID:27905492

Effects of Frequent Hemodialysis on Ventricular Volumes and Left Ventricular Remodeling

PubMed Central

Greene, Tom; Chertow, Glenn M.; Kliger, Alan S.; Stokes, John B.; Beck, Gerald J.; Daugirdas, John T.; Kotanko, Peter; Larive, Brett; Levin, Nathan W.; Mehta, Ravindra L.; Rocco, Michael; Sanz, Javier; Yang, Phillip C.; Rajagopalan, Sanjay

2013-01-01

Summary Background and objectives Higher left ventricular volume is associated with death in patients with ESRD. This work investigated the effects of frequent hemodialysis on ventricular volumes and left ventricular remodeling. Design, setting, participants, & measurements The Frequent Hemodialysis Network daily trial randomized 245 patients to 12 months of six times per week versus three times per week in-center hemodialysis; the Frequent Hemodialysis Network nocturnal trial randomized 87 patients to 12 months of six times per week nocturnal hemodialysis versus three times per week predominantly home-based hemodialysis. Left and right ventricular end systolic and diastolic volumes, left ventricular mass, and ejection fraction at baseline and end of the study were ascertained by cardiac magnetic resonance imaging. The ratio of left ventricular mass/left ventricular end diastolic volume was used as a surrogate marker of left ventricular remodeling. In each trial, the effect of frequent dialysis on left or right ventricular end diastolic volume was tested between predefined subgroups. Results In the daily trial, frequent hemodialysis resulted in significant reductions in left ventricular end diastolic volume (−11.0% [95% confidence interval, −16.1% to −5.5%]), left ventricular end systolic volume (−14.8% [−22.7% to −6.2%]), right ventricular end diastolic volume (−11.6% [−19.0% to −3.6%]), and a trend for right ventricular end systolic volume (−11.3% [−21.4% to 0.1%]) compared with conventional therapy. The magnitude of reduction in left and right ventricular end diastolic volumes with frequent hemodialysis was accentuated among patients with residual urine output<100 ml/d (P value [interaction]=0.02). In the nocturnal trial, there were no significant changes in left or right ventricular volumes. The frequent dialysis interventions had no substantial effect on the ratio of left ventricular mass/left ventricular end diastolic volume in either

Experience with a "hotline" service for outpatients on a ventricular assist device.

PubMed

Biefer, Hector Rodriguez Cetina; Sündermann, Simon Harald; Emmert, Maximilian Yosri; Hasenclever, Peter; Lachat, Mario Louis; Falk, Volkmar; Wilhelm, Markus Johannes

2014-08-01

With the growing number of outpatients on ventricular assist devices (VADs), there is an increasing need for "home discharge programs." One important feature is a 24-hour telephone service. In our center, the perfusionists run a so-called "hotline" for all of our VAD patients. This study analyzes the hotline calls with regard to frequency, the reason for calling, and the type of action undertaken. Over a period of 5 years, 16 (12 EXCOR and 4 INCOR; Berlin Heart, Berlin, Germany) of 33 VAD patients (48%) were discharged and instructed to use the "hotline" service. All the calls received by the perfusionists were reviewed. We classified the calls into three levels according to the severity of the problem: Level (L) 1 = assistance provided by the perfusionist alone; L2 = calls requiring discussion with the surgeon on duty and/or visit to the outpatient clinic ahead of time; and L3 = immediate action and/or admission to the hospital. Over a period of 2,890 outpatient days (7.9 years), a total of 26 calls were registered. There were 0.9 calls per 100 patient days and 1.6 calls per discharged patient. Out of the 26 calls, 14 calls (54%) were classified as L1, 8 (31%) as L2, and 4 (15%) as L3. The most frequent reasons for L1 or L2 calls were fibrin deposits in the EXCOR pump chamber (39%), followed by battery dysfunction (19%). L3 calls were related to dysfunction of the EXCOR driving units in three cases and to an EXCOR pump chamber disconnection, which the patient did not survive. The institution of a hotline is an essential component of a VAD outpatient program. It provides a certain level of safety for the patient, although a residual risk remains. Georg Thieme Verlag KG Stuttgart · New York.

Long-Term Survival in Patients Receiving a Continuous-Flow Left Ventricular Assist Device.

PubMed

Gosev, Igor; Kiernan, Michael S; Eckman, Peter; Soleimani, Behzad; Kilic, Ahmet; Uriel, Nir; Rich, Jonathan D; Katz, Jason N; Cowger, Jennifer; Lima, Brian; McGurk, Siobhan; Brisco-Bacik, Meredith A; Lee, Sanjin; Joseph, Susan M; Patel, Chetan B

2018-03-01

Long-term survivors after implantation of left ventricular assist devices (LVADs) are increasing in prevalence. We describe the characteristics and outcomes in patients surviving longer than 4 years on LVAD support. We performed a multicenter, retrospective analysis of patients surviving at least 4 years on continuous-flow LVAD (CF-LVAD) support with a HeartMate II at centers participating in the Evolving Mechanical support Research Group. Between 2005 and 2010, 156 long-term survivors were identified with a mean survival of 7.1 years (95% confidence interval: 6.7 to 7.5 years). The mean age was 58.2 ± 15.2 years and 30.1% were women. Readmission rate was low at 1.1 events per patient per year with the most common reasons leading to readmission being infection (0.10 readmissions per patient per year) and gastrointestinal bleeding (0.07 readmissions per patient per year). Two years after implantation, 97% of patients were either New York Heart Association functional class I or II, with 92% at 4 years. Patients surviving 4 years on CF-LVAD support can anticipate ongoing long-term survival with sustained improvements in functionality and low rates of rehospitalization. Copyright © 2018 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Right ventricular response to pulsatile load is associated with early right heart failure and mortality after left ventricular assist device.

PubMed

Grandin, E Wilson; Zamani, Payman; Mazurek, Jeremy A; Troutman, Gregory S; Birati, Edo Y; Vorovich, Esther; Chirinos, Julio A; Tedford, Ryan J; Margulies, Kenneth B; Atluri, Pavan; Rame, J Eduardo

2017-01-01

Right ventricular (RV) adaptation to afterload is crucial for patients undergoing continuous-flow left ventricular assist device (cf-LVAD) implantation. We hypothesized that stratifying patients by RV pulsatile load, using pulmonary arterial compliance (PAC), and RV response to load, using the ratio of central venous to pulmonary capillary wedge pressure (CVP:PCWP), would identify patients at high risk for early right heart failure (RHF) and 6-month mortality after cf-LVAD. During the period from January 2008 to June 2014, we identified 151 patients at our center with complete hemodynamics prior to cf-LVAD. Pulsatile load was estimated using PAC indexed to body surface area (BSA), according to the formula: indexed PAC (PACi) = [SV / (PA systolic - PA diastolic )] / BSA, where SV is stroke volume and PA is pulmonary artery. Patients were divided into 4 hemodynamic groups by PACi and CVP:PCWP. RHF was defined as the need for unplanned RVAD, inotropic support ≥14 days or death due to RHF within 14 days. Risk factors for RHF and 6-month mortality were examined using logistic regression and Cox proportional hazards modeling. Sixty-one patients (40.4%) developed RHF and 34 patients (22.5%) died within 6 months. Patients with RHF had lower PACi (0.92 vs 1.17 ml/mm Hg/m 2 , p = 0.008) and higher CVP:PCWP (0.48 vs 0.37, p = 0.001). Higher PACi was associated with reduced risk of RHF (adjusted odds ratio [adj-OR] 0.61, 95% confidence interval [CI] 0.39 to 0.94, p = 0.025) and low PACi with increased risk of 6-month mortality (adjusted hazard ratio [adj-HR] 3.18, 95% CI 1.40 to 7.25, p = 0.006). Compared to patients with low load (high PACi) and adequate right heart response to load (low CVP:PCWP), patients with low PACi and high CVP:PCWP had an increased risk of RHF (OR 4.74, 95% CI 1.23 to 18.24, p = 0.02) and 6-month mortality (HR 8.68, 95% CI 2.79 to 26.99, p < 0.001). A hemodynamic profile combining RV pulsatile load and response to load identifies patients at high

Levitronix bilateral ventricular assist device, a bridge to recovery in a patient with acute fulminant myocarditis and concomitant cerebellar infarction.

PubMed

Huang, Yi-Fan; Hsu, Po-Shun; Tsai, Chien-Sung; Tsai, Yi-Ting; Lin, Chih-Yuan; Ke, Hong-Yan; Lin, Yi-Chang; Yang, Hsiang-Yu

2018-02-07

We report on the case of a 27-year-old male who presented to our emergency room with chest tightness, dyspnoea and cold sweats. The 12-lead electrocardiogram showed diffuse ventricular tachycardia with wide QRS complexes. Troponin-I level was elevated to 100 ng/ml. The coronary angiogram showed good patency of all three coronary vessels, and acute fulminant myocarditis was suspected. The patient underwent cardiopulmonary resuscitation in the catheter room and high-dose inotropic support was initiated to stabilise his haemodynamic status. After resuscitation, the patient was in a coma and acute stroke was highly suspected. In addition, deteriorating cardiogenic shock with acute renal failure and pulmonary oedema were also detected. Due to haemodynamic compromise despite high-dose inotropic support, a Levitronix ® bilateral ventricular assist device (Bi-VAD) was implanted on an emergency basis for circulatory support. Postoperative brain computed tomography revealed acute left cerebellar infarction. Because the patient had left cerebellar infarction with right hemiplegia, heart transplantation was contraindicated. Eventually, cardiac systolic function recovered well and the patient underwent successful Bi-VAD removal after a total of 18 days on Levitronix ® haemodynamic support. He was weaned from the ventilator two weeks later and was discharged 10 days later.

Heat Generation in Axial and Centrifugal Flow Left Ventricular Assist Devices.

PubMed

Yost, Gardner; Joseph, Christine Rachel; Royston, Thomas; Tatooles, Antone; Bhat, Geetha

Despite increasing use of left ventricular assist devices (LVADs) as a surgical treatment for advanced heart failure in an era of improved outcomes with LVAD support, the mechanical interactions between these pumps and the cardiovascular system are not completely understood. We utilized an in vitro mock circulatory loop to analyze the heat production incurred by operation of an axial flow and centrifugal flow LVAD. A HeartMate II and a HeartWare HVAD were connected to an abbreviated flow loop and were implanted in a viscoelastic gel. Temperature was measured at the surface of each LVAD. Device speed and fluid viscosity were altered and, in the HeartMate II, as artificial thrombi were attached to the inflow stator, impeller, and outflow stator. The surface temperatures of both LVADs increased in all trials and reached a plateau within 80 minutes of flow initiation. Rate of heat generation and maximum system temperature were greater when speed was increased, when viscosity was increased, and when artificial thrombi were attached to the HeartMate II impeller. Normal operation of these two widely utilized LVADs results in appreciable heat generation in vitro. Increased pump loading resulted in more rapid heat generation, which was particularly severe when a large thrombus was attached to the impeller of the HeartMate II. While heat accumulation in vivo is likely minimized by greater dissipation in the blood and soft tissues, focal temperature gains with the pump housing of these two devices during long-term operation may have negative hematological consequences.

Development and evaluation of endurance test system for ventricular assist devices.

PubMed

Sumikura, Hirohito; Homma, Akihiko; Ohnuma, Kentaro; Taenaka, Yoshiyuki; Takewa, Yoshiaki; Mukaibayashi, Hiroshi; Katano, Kazuo; Tatsumi, Eisuke

2013-06-01

We developed a novel endurance test system that can arbitrarily set various circulatory conditions and has durability and stability for long-term continuous evaluation of ventricular assist devices (VADs), and we evaluated its fundamental performance and prolonged durability and stability. The circulation circuit of the present endurance test system consisted of a pulsatile pump with a small closed chamber (SCC), a closed chamber, a reservoir and an electromagnetic proportional valve. Two duckbill valves were mounted in the inlet and outlet of the pulsatile pump. The features of the circulation circuit are as follows: (1) the components of the circulation circuit consist of optimized industrial devices, giving durability; (2) the pulsatile pump can change the heart rate and stroke length (SL), as well as its compliance using the SCC. Therefore, the endurance test system can quantitatively reproduce various circulatory conditions. The range of reproducible circulatory conditions in the endurance test circuit was examined in terms of fundamental performance. Additionally, continuous operation for 6 months was performed in order to evaluate the durability and stability. The circulation circuit was able to set up a wide range of pressure and total flow conditions using the SCC and adjusting the pulsatile pump SL. The long-term continuous operation test demonstrated that stable, continuous operation for 6 months was possible without leakage or industrial device failure. The newly developed endurance test system demonstrated a wide range of reproducible circulatory conditions, durability and stability, and is a promising approach for evaluating the basic characteristics of VADs.

Cardiovascular implantable electronic device infections in left ventricular assist device recipients.

PubMed

Riaz, Talha; Nienaber, Juhsien J C; Baddour, Larry M; Walker, Randall C; Park, Soon J; Sohail, Muhammad Rizwan

2014-02-01

Most patients with left ventricular assist devices (LVADs) have concomitant cardiovascular implantable electronic devices (CIEDs). However, clinical presentation and outcome of CIED infection in the setting of LVAD has not been previously described. We retrospectively reviewed 247 patients who underwent LVAD implantation at Mayo Clinic campuses in Minnesota, Arizona, and Florida, from January 2005 to December 2011. Demographic and clinical data of patients who met criteria for CIED infection were extracted. Of 247 patients with LVADs, 215 (87%) had CIED at the time of LVAD implantation and six (2.8%) subsequently developed CIED infections. Three patients developed CIED lead-related endocarditis and the other three had pocket infection. All three instances of CIED pocket infection were preceded by device generator exchange, whereas all three patients with CIED lead-related endocarditis had prior LVAD-related infections. Causative pathogens included Pseudomonas aeruginos (1), coagulase-negative staphylococci (2), methicillin-resistant Staphylococcus aureus (1), a gram-positive bacillus (1), and culture negative (2). All patients underwent complete CIED removal along with antimicrobial therapy. The three patients with CIED lead-related endocarditis and prior LVAD infections received chronic suppressive antibiotic therapy, and one patient had LVAD exchange. All but one remained alive at the last follow-up with a median duration of 15 months (7-46 months) from the time of CIED infection. Patients who are receiving LVAD therapy and develop CIED infection should be managed with complete CIED removal. Chronic suppressive antibiotic therapy is warranted in cases that have concomitant LVAD infection. ©2013, The Authors. Journal compilation ©2013 Wiley Periodicals, Inc.

Successful repair of a ventricular assist system percutaneous lead.

PubMed

Pantalos, G M; Marks, J D; Richardson, E E; Nelson, K E; Long, J W

1999-01-01

A patient with an implanted, electrically powered, ventricular assist device (Thermo Cardiosystems VE HeartMate) experienced a partial break of the percutaneous lead 5 months after implantation. The break (limited to the Silicone rubber tube) occurred at the junction of the lead with the Y-connector to the controller and vent, leaving approximately 5 cm of exposed lead from the skin exit site to the connector. Electronic and pumping functions of the pump continued, but the opening in the lead (which went more that half way around the circumference) prevented the use of pneumatic actuation as a back-up mode for pump operation, and placed the pump at risk for contamination. Repair of the lead without surgical intervention was desirable, with ease of repair and minimal risk to the patient being the top priorities. The use of multiple layers of heat-shrink tubing or external metal stents was ruled out in favor of a three stage repair procedure. The first stage involved the removal of the Dacron velour in-growth material from the lead to expose the underlying Silicone rubber tube. While the opening in the tube was held shut, a coating of medical grade Silicone rubber adhesive was applied to the tube, then wrapped with a woven Dacron mesh, followed by two layers of plastic wrapping material to protect the adhesive. This initial layer was secured by an external stent of tubing with cable ties. After several days to allow for complete curing of the adhesive, the adhesive coating with mesh was repeated. The final step involved a double layer wrap of a 1 mm thick Silicone rubber sheeting with mesh incorporation and adhesive secured in place with cable ties. After completion of the repair and verification of the ability to operate the device with pneumatic actuation, the patient was discharged with no recurrence of the problem after 8 months of weekly follow-up. This experience demonstrates the need to clinically anticipate component repair or replacement without total device

The Effect of Preoperative Cognitive Behavior and Exercise Therapy for a Patient With an Implanted Left Ventricular Assist Device in Korea.

PubMed

Seo, Yong Gon; Park, Won Hah; Jeon, Eun Seok; Sung, Ji Dong; Jang, Mi Ja

2017-10-01

Left ventricular assist devices (LVADs) are used in patients with progressive heart failure symptoms to provide circulatory support. Patients with LVADs are referred to inpatient cardiac rehabilitation to prevent postoperative complications and improve aerobic capacity and quality of life. Preoperative exercise therapy for cardiac patients is an emerging treatment modality, and several studies have reported that it improves postoperative outcomes, such as length of hospital stay and postoperative complications. This case report describes the benefits of preoperative cognitive behavioral and exercise therapy in a Korean patient undergoing LVAD implantation. V. Copyright © 2017 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Single-Center Experience With HeartMate II Left Ventricular Assist Device Explantation.

PubMed

Tchantchaleishvili, Vakhtang; Cheyne, Christina; Sherazi, Saadia; Melvin, Amber L; Hallinan, William; Chen, Leway; Todd Massey, Howard

2016-12-01

In patients with continuous flow left ventricular assist devices (CF-LVADs) myocardial recovery is uncommon. Given the heterogeneity of the population implanted and low incidence of recovery, the discovery of native left ventricular (LV) recovery and criteria for explantation of CF-LVAD system is not clearly determined. We sought to analyze the characteristics of the patients who underwent CF-LVAD explantation at our institution. Prospectively collected data on patients supported with CF-LVADs were reviewed retrospectively. Patients who underwent CF-LVAD explants were identified and their characteristics were analyzed with a focus on patient presentation and determinants of explantability. From November 2006 to June 2014, 223 patients (181 male, 42 female) underwent implantation of HeartMate II LVAD. Seven female (16.7%) and one male (0.6%) patients were explanted (P < 0.001). Mean age was 43 ± 9 years and etiology for cardiomyopathy was ischemic in three (37.5%) patients, nonischemic in four (50%) patients, and mixed in the one (12.5%) male patient of the cohort. Five (62.5%) patients presented acutely with significant hemolysis, and were found to have LV improvement as well as reduced, absent, or reversed diastolic flow velocities on echocardiography. Overall, mean lactate dehydrogenase level before explantation was 1709 ± 1168 U/L compared to the mean baseline level of 601 ± 316 U/L (P = 0.048). Mean LV ejection fraction (LVEF) improved from 17 ± 7% preimplant to 56 ± 11% pre-explantation (P < 0.001). Median number of days on CF-LVAD support was 870 (interquartile range, 209-975) while mean duration of follow-up after the CF-LVAD explantation was 276 ± 240 days. Mean LVEF dropped from 46 ± 19% postexplantation to 34 ± 10% during the most recent follow-up (P = 0.015). At our institution, patients who underwent LVAD explants were predominantly women with nonischemic cardiomyopathy. Clinical evidence of

Percutaneous left ventricular assist device with TandemHeart for high-risk percutaneous coronary intervention: the Mayo Clinic experience.

PubMed

Alli, Oluseun O; Singh, Inder M; Holmes, David R; Pulido, Juan N; Park, Soon J; Rihal, Charanjit S

2012-11-01

In patients with poor left ventricular function and severe left main or multivessel coronary disease, coronary artery bypass grafting (CABG) surgery has been the preferred therapy. However, a number of these patients are either inoperable or poor surgical candidates due to comorbid conditions and previous cardiac surgical procedures. These patients are generally poor candidates for standard percutaneous coronary intervention (PCI) techniques. A hybrid PCI approach with hemodynamic support may be a viable strategy for these patients. We report our experience using the TandemHeart percutaneous left ventricular assist device during high-risk PCI. Retrospective cross-sectional analysis of prospectively collected data in 54 patients undergoing high-risk PCI using the TandemHeart device for support. Hemodynamic and clinical data were collected and analyzed. Baseline clinical characteristics were as follows: mean age 72 ± 1.7 years, males 78%, median ejection fraction 20%, mean serum creatinine 1.6 ± 0.3 2 mg/dL, recent myocardial infarction 52%, COPD 33%, previous CABG 50%, diabetes mellitus 41%, and hypertension 83%. The median SYNTAX score was 33, and the median Jeopardy score was 10. The predicted surgical revascularization mortality was 13% by the Society for Thoracic Surgery risk score and 33% by Euroscore. There was a significant decrease in right and left heart pressures (P < 0.05) with a concomitant increase in the cardiac output from 4.7 to 5.7 L/min (P = 0.03) during TandemHeart support. Left main and multivessel PCI was performed in 62% of patients, and rotablation was used in 48%. Procedural success rate was 97%, whereas 30-day and 6 month survival were 90% and 87%, respectively. Major vascular complications occurred in 13% of cases. None of our patients developed contrast induced nephropathy or needed dialysis. High-risk PCI with percutaneous left ventricular support using TandemHeart is a viable therapeutic strategy for a select subset of patients at very

The Ventricular Assist Device in the Life of the Child: A Phenomenological Pediatric Study

PubMed Central

van Manen, Michael A.

2017-01-01

What is it like for a child to live with an artificial heart? The use of some medical therapies in children requires developmental considerations, is associated with psychosocial consequences, and calls for ethical sensitivities. A critical case is the ventricular assist device (VAD), a mechanical pump used to support the functioning of a failing heart. As a pediatric therapy, the device can be used as a temporary solution for poor heart function, a bridge to transplantation or recovery, or as a destination therapy. While the mechanical-technical operation of the VAD is well understood, the clinical-technical aspects of young people living with this device are largely unexplored. Drawing on interviews of school-aged children, the aim of this phenomenological study is to explore how a VAD may structure or condition a child’s meaningful experience of their world outside the hospital. The driveline of an implanted VAD is the peripheral attachment, extruding through the skin to connect the controller-power supply. The materiality of the device may be interruptive, restrictive, and disturbing to the psycho-physical being and sense of self-identity of the child as a child. And while a child equipped with a VAD is not necessarily conspicuous among other children, the child may experience the device as an exposing presence, while living with the worry of a caregiver who takes on the role not simply of parent but of watchful health professional. A phenomenological understanding of the VAD should assist parents and caregiving health professionals knowing how to deal with specific issues arising in the life of the VAD child. PMID:28682718

Outcomes of ventricular assist device implantation in children and young adults: the Melbourne experience.

PubMed

Shi, William Y; Marasco, Silvana F; Saxena, Pankaj; d'Udekem, Yves; Yong, Matthew S; Mitnovetski, Sergei; Brizard, Christian P; McGiffin, David C; Weintraub, Robert G; Konstantinov, Igor E

2016-12-01

We evaluated our experience with ventricular assist device (VAD) implantation in children and young adults. A total of 64 patients underwent VAD implantation in two centres. The mean age was 15 ± 7.2 years. Thirty-five (55%) patients were under 18 years of age. Devices implanted included the Thoratec Paracorporeal in 30 (47%) patients, Berlin Heart EXCOR in 11 (17%) and VentrAssist in 14 (22%). The diagnosis was cardiomyopathy in 53, congenital heart disease in 11, and graft failure in four patients. There were 10 (16%) in-hospital deaths. Mortality was higher in patients <18 years of age (26% compared with 3.4% for those ≥18 years, P = 0.02). The use of extracorporeal membrane oxygenation prior to VAD implantation was associated with higher mortality (P = 0.006). Seventeen (27%) patients experienced stroke. Nine patients (14%) required change of VAD because of thrombosis. Transplantation was performed in 44 patients after a mean of 131 ± 141 days on VAD, 11 patients died without transplantation and three patients currently await transplantation. The VAD was explanted in six patients because of recovery. Overall survival from VAD implantation was 69% and 61% at 5 and 10 years, respectively. The 5-year post-transplant survival for those bridged with VAD support was 91% and was comparable with a cohort of patients who did not receive a pre-transplant VAD. Children requiring pre-transplant VAD support have a higher mortality and morbidity compared with young adults. Survival after heart transplantation those supported with VADs was similar to patients of similar age who did not require pre-transplant support. © 2015 Royal Australasian College of Surgeons.

Value of right ventricular mapping in patients with postinfarction ventricular tachycardia.

PubMed

Yokokawa, Miki; Good, Eric; Crawford, Thomas; Chugh, Aman; Pelosi, Frank; Latchamsetty, Rakesh; Oral, Hakan; Morady, Fred; Bogun, Frank

2012-06-01

Postinfarction ventricular tachycardia (VT) typically involves the left ventricular endocardium. Right ventricular involvement in the arrhythmogenic substrate of postinfarction VT is considered unusual. To assess the role of right ventricular mapping and ablation in patients with prior septal myocardial infarction. From among 37 consecutive patients with recurrent postinfarction VT, 18 patients with evidence of left ventricular septal involvement of myocardial infarction were identified; these patients were the subjects of this report. In these 18 patients, 166 VTs (cycle length 372 ± 117 ms) were induced. Right ventricular voltage mapping was performed in all 18 patients with left ventricular septal myocardial infarction. Right ventricular voltage mapping showed areas of low voltage in 11 patients; pace mapping from these areas revealed matching pace maps for 17 VTs, and radiofrequency ablation from the right ventricular endocardium but not the left ventricular endocardium eliminated 14 of 17 VTs. VTs with critical components in the right ventricle had a left bundle branch block morphology that had similar characteristics as left bundle branch block VTs with critical areas involving the left ventricular septum. Patients with right ventricular VT breakthrough sites had a lower ejection fraction than did patients without VT breaking out on the right ventricular septum (18% ± 5% vs 33% ± 15%; P = .01). Right ventricular mapping and ablation may be necessary in order to eliminate all inducible VTs in patients with postinfarction VT. More than half the patients with septal myocardial infarction have right ventricular septal areas that are critical for postinfarction VT and that cannot be eliminated by left ventricular ablation alone. Copyright © 2012 Heart Rhythm Society. All rights reserved.

Stroke Risk and Mortality in Patients with Ventricular Assist Devices

PubMed Central

Parikh, Neal S.; Cool, Joséphine; Karas, Maria G.; Boehme, Amelia K.; Kamel, Hooman

2016-01-01

Background and Purpose Ventricular assist devices (VADs) have advanced the management of end-stage heart failure. However, these devices are associated with hemorrhagic and thrombotic complications, including stroke. We assessed the incidence, risk factors, and outcomes of ischemic and hemorrhagic stroke after VAD placement. Methods Using administrative claims data from acute care hospitals in California, Florida, and New York from 2005–2013, we identified patients who underwent VAD placement, defined by International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) code 37.66. Ischemic and hemorrhagic strokes were identified by previously validated coding algorithms. We used survival statistics to determine incidence rates and Cox proportional hazard analyses to examine associations. Results Among 1,813 patients, we identified 201 ischemic strokes and 116 hemorrhagic strokes during 3.4 (±2.0) years of follow-up after implantation of a VAD. The incidence of stroke was 8.7% per year (95% confidence interval [CI], 7.7–9.7%). The annual incidence of ischemic stroke (5.5%; 95% CI, 4.8–6.4%) was nearly double that of hemorrhagic stroke (3.1%; 95% CI, 2.6–3.8%). Women faced a higher hazard of stroke than men (hazard ratio [HR], 1.6; 95% CI, 1.2–2.1), particularly hemorrhagic stroke (HR, 2.2; 95% CI, 1.4–3.4). Stroke was strongly associated with subsequent in-hospital mortality (HR, 6.1; 95% CI, 4.6–7.9). Conclusions The incidence of stroke after VAD implantation was 8.7% per year, and incident stroke was strongly associated with subsequent in-hospital mortality. Notably, ischemic stroke occurred at nearly twice the rate of hemorrhagic stroke. Women appeared to face a higher risk for hemorrhagic stroke than men. PMID:27650070

Stroke Risk and Mortality in Patients With Ventricular Assist Devices.

PubMed

Parikh, Neal S; Cool, Joséphine; Karas, Maria G; Boehme, Amelia K; Kamel, Hooman

2016-11-01

Ventricular assist devices (VADs) have advanced the management of end-stage heart failure. However, these devices are associated with hemorrhagic and thrombotic complications, including stroke. We assessed the incidence, risk factors, and outcomes of ischemic and hemorrhagic stroke after VAD placement. Using administrative claims data from acute care hospitals in California, Florida, and New York from 2005 to 2013, we identified patients who underwent VAD placement, defined by the International Classification of Diseases, Ninth Revision, Clinical Modification code 37.66. Ischemic and hemorrhagic strokes were identified by previously validated coding algorithms. We used survival statistics to determine the incidence rates and Cox proportional hazard analyses to examine the associations. Among 1813 patients, we identified 201 ischemic strokes and 116 hemorrhagic strokes during 3.4 (±2.0) years of follow-up after implantation of a VAD. The incidence of stroke was 8.7% per year (95% confidence interval [CI], 7.7-9.7). The annual incidence of ischemic stroke (5.5%; 95% CI, 4.8-6.4) was nearly double that of hemorrhagic stroke (3.1%; 95% CI, 2.6-3.8). Women faced a higher hazard of stroke than men (hazard ratio, 1.6; 95% CI, 1.2-2.1), particularly hemorrhagic stroke (hazard ratio, 2.2; 95% CI, 1.4-3.4). Stroke was strongly associated with subsequent in-hospital mortality (hazard ratio, 6.1; 95% CI, 4.6-7.9). The incidence of stroke after VAD implantation was 8.7% per year, and incident stroke was strongly associated with subsequent in-hospital mortality. Notably, ischemic stroke occurred at nearly twice the rate of hemorrhagic stroke. Women seemed to face a higher risk for hemorrhagic stroke than men. © 2016 American Heart Association, Inc.

Selling to NASA

NASA Technical Reports Server (NTRS)

1981-01-01

The prospective NASA contractor is provided with information that describes the agency and its procurement practices. Products include ideas, manufacturing capabilities, fabricated components, construction, basic materials, and specialized services. NASA assistance in marketing these and other products is emphasized. Small and minority business enterprises are discussed. The agency's scientific and technical information activities are also discussed.

Effect of Neurohormonal Blockade Drug Therapy on Outcomes and Left Ventricular Function and Structure After Left Ventricular Assist Device Implantation.

PubMed

Grupper, Avishay; Zhao, Yanjun M; Sajgalik, Pavol; Joyce, Lyle D; Park, Soon J; Pereira, Naveen L; Stulak, John M; Burnett, John C; Edwards, Brooks S; Daly, Richard C; Kushwaha, Sudhir S; Schirger, John A

2016-06-01

Neurohormonal blockade drug therapy (NHBDT) is the cornerstone therapy in heart failure (HF) management for promoting reverse cardiac remodeling and improving outcomes. It's utility in left ventricular assist device (LVAD) supported patients remains undefined. Sixty-four patients who received continuous flow LVAD at our institution were retrospectively reviewed and divided into 2 groups: no-NHBDT group (n = 33) received LVAD support only and NHBDT group (n = 31) received concurrent NHBDT based on the clinical judgment of the attending physicians. Cardiac remodeling (echocardiographic parameters and biomarkers) and clinical outcome (functional status, HF-related hospital readmissions, and mortality) data were collected. A statistically significant increase in ejection fraction, decrease in LV end-diastolic diameter index and LV mass index, and a sustained reduction in N-terminal pro B-type natriuretic peptide (NTproBNP) were observed in the NHBDT group at 6 months after LVAD implant (p <0.05). NHBDT-treated patients experienced significantly greater improvement in New York Heart Association functional classification and 6-minute-walk distance throughout the study. The combined end point of cardiovascular death or HF hospitalization was significantly reduced in patients receiving NHBDT (p = 0.013) associated primarily with a 12.1% absolute reduction in HF-related hospitalizations (p = 0.046). In conclusion, NHBDT in LVAD-supported patients is associated with a significant reversal in adverse cardiac remodeling and a reduction in morbidity and mortality compared with LVAD support alone. Copyright © 2016 Elsevier Inc. All rights reserved.

NASA Education Stakeholder's Summit

NASA Image and Video Library

2010-09-12

NASA Administrator Charles Bolden, far right, gives keynote remarks at the NASA Education Stakeholders’ Summit One Stop Shopping Initiative (OSSI), Monday, Sep. 13, 2010, at the Westfields Marriott Conference Center in Chantilly, VA. Administrator Bolden is joined on the panel from left to right by Leland Melvin, Education Design Team Co-Chair and NASA Astronaut; William Kelly, Manager, Public Affairs, American Society for Engineering Education; Michael Lach, Special Assistant for STEM Education, U.S. Department of Education; Cora Marrett, Acting Director, National Science Foundation; and James Stofan, NASA Acting Associate Administrator for Education. (Photo Credit: NASA/Carla Cioffi)

Association between cell-derived microparticles and adverse events in patients with nonpulsatile left ventricular assist devices

PubMed Central

Nascimbene, Angelo; Hernandez, Ruben; George, Joggy K.; Parker, Anita; Bergeron, Angela L.; Pradhan, Subhashree; Vijayan, K. Vinod; Civitello, Andrew; Simpson, Leo; Nawrot, Maria; Lee, Vei-Vei; Mallidi, Hari R.; Delgado, Reynolds M.; Dong, Jing Fei; Frazier, O.H.

2014-01-01

BACKGROUND Continuous-flow left ventricular assist devices (LVADs) expose blood cells to high shear stress, potentially resulting in the production of microparticles that express phosphatidylserine (PS+) and promote coagulation and inflammation. In this prospective study, we attempted to determine whether PS+ microparticle levels correlate with clinical outcomes in LVAD-supported patients. METHODS We enrolled 20 patients undergoing implantation of the HeartMate II LVAD and 10 healthy controls who provided reference values for the microparticle assays. Plasma was collected before LVAD implantation, at discharge, at 3-month follow-up, and when an adverse clinical event occurred. We quantified PS+ microparticles in the plasma using flow cytometry. RESULTS During the study period, 8 patients developed adverse clinical events: ventricular tachycardia storm (n=1), non–ST-elevation myocardial infarction (n=2), arterial thrombosis (n=2), gastrointestinal bleeding (n=2), and stroke (n=3). Levels of PS+ microparticles were higher in patients at baseline than in healthy controls (2.11%±1.26 vs 0.69±0.46, P=0.007). After LVAD implantation, patient PS+ microparticle levels increased to 2.39%±1.22 at discharge and then leveled to 1.97%±1.25 at 3-month follow-up. Importantly, patients who developed an adverse event had significantly higher levels of PS+ microparticles than did patients with no events (3.82%±1.17 vs 1.57%±0.59, P<0.001), even though the 2 patient groups did not markedly differ in other clinical and hematologic parameters. CONCLUSIONS Our results suggest that an elevation of PS+ microparticle levels may be associated with adverse clinical events. Thus, measuring PS+ microparticle levels in LVAD-supported patients may help identify patients at increased risk for adverse events. PMID:24656391

Association between cell-derived microparticles and adverse events in patients with nonpulsatile left ventricular assist devices.

PubMed

Nascimbene, Angelo; Hernandez, Ruben; George, Joggy K; Parker, Anita; Bergeron, Angela L; Pradhan, Subhashree; Vijayan, K Vinod; Civitello, Andrew; Simpson, Leo; Nawrot, Maria; Lee, Vei-Vei; Mallidi, Hari R; Delgado, Reynolds M; Dong, Jing Fei; Frazier, O H

2014-05-01

Continuous-flow left ventricular assist devices (LVADs) expose blood cells to high shear stress, potentially resulting in the production of microparticles that express phosphatidylserine (PS+) and promote coagulation and inflammation. In this prospective study, we attempted to determine whether PS+ microparticle levels correlate with clinical outcomes in LVAD-supported patients. We enrolled 20 patients undergoing implantation of the HeartMate II LVAD (Thoratec Corp, Pleasanton, CA) and 10 healthy controls who provided reference values for the microparticle assays. Plasma was collected before LVAD implantation, at discharge, at the 3-month follow-up, and when an adverse clinical event occurred. We quantified PS+ microparticles in the plasma using flow cytometry. During the study period, 8 patients developed adverse clinical events: ventricular tachycardia storm in 1, non-ST-elevation myocardial infarction in 2, arterial thrombosis in 2, gastrointestinal bleeding in 2, and stroke in 3. Levels of PS+ microparticles were higher in patients at baseline than in healthy controls (2.11% ± 1.26% vs 0.69% ± 0.46%, p = 0.007). After LVAD implantation, patient PS+ microparticle levels increased to 2.39% ± 1.22% at discharge and then leveled to 1.97% ± 1.25% at the 3-month follow-up. Importantly, levels of PS+ microparticles were significantly higher in patients who developed an adverse event than in patients with no events (3.82% ± 1.17% vs 1.57% ± 0.59%, p < 0.001), even though the 2 patient groups did not markedly differ in other clinical and hematologic parameters. Our results suggest that an elevation of PS+ microparticle levels may be associated with adverse clinical events. Thus, measuring PS+ microparticle levels in LVAD-supported patients may help identify patients at increased risk for adverse events. Copyright © 2014 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

Magnetic resonance imaging during untreated ventricular fibrillation reveals prompt right ventricular overdistention without left ventricular volume loss.

PubMed

Berg, Robert A; Sorrell, Vincent L; Kern, Karl B; Hilwig, Ronald W; Altbach, Maria I; Hayes, Melinda M; Bates, Kathryn A; Ewy, Gordon A

2005-03-08

Most out-of-hospital ventricular fibrillation (VF) is prolonged (>5 minutes), and defibrillation from prolonged VF typically results in asystole or pulseless electrical activity. Recent visual epicardial observations in an open-chest, open-pericardium model of swine VF indicate that blood flows from the high-pressure arterial system to the lower-pressure venous system during untreated VF, thereby overdistending the right ventricle and apparently decreasing left ventricular size. Therefore, inadequate left ventricular stroke volume after defibrillation from prolonged VF has been postulated as a major contributor to the development of pulseless rhythms. Ventricular dimensions were determined by MRI for 30 minutes of untreated VF in a closed-chest, closed-pericardium model in 6 swine. Within 1 minute of untreated VF, mean right ventricular volume increased by 29% but did not increase thereafter. During the first 5 minutes of untreated VF, mean left ventricular volume increased by 34%. Between 20 and 30 minutes of VF, stone heart occurred as manifested by dramatic thickening of the myocardium and concomitant substantial decreases in left ventricular volume. In this closed-chest swine model of VF, substantial right ventricular volume changes occurred early and did not result in smaller left ventricular volumes. The changes in ventricular volumes before the late development of stone heart do not explain why defibrillation from brief duration VF (<5 minutes) typically results in a pulsatile rhythm with return of spontaneous circulation, whereas defibrillation from prolonged VF (5 to 15 minutes) does not.

Development and evaluation of a long-term, implantable, electrically actuated left ventricular assist system: THI/Gould LVAS.

PubMed

Norman, J C; McGee, M G; Fuqua, J M; Igo, S R; Turner, S A; Sterling, R; Urrutia, C O; Frazier, O H; Clay, W C; Chambers, J A

1983-02-01

A long-term, implantable, electrically actuated left ventricular assist system (THI/Gould LVAS) is being developed and characterized in vitro and in vivo for utilization in patients with end-stage heart disease. This system consists of five major components: a long-term, implantable blood pump (THI E-type ALVAD); an electrical-mechanical energy converter (Gould Model V); a control unit with batteries; a volume compensation system; and an external power supply and monitoring unit. Two of these components (blood pump and electrical-mechanical energy converter) have been integrated, and are undergoing chronic in vivo evaluations in calves. Thus far, 44 pneumatically and electrically actuated THI/Gould LVAS evaluations have been performed. This experience has resulted in greater than 6.5 years of actuation in vivo, with durations exceeding 1 year. System in vivo performance in terms of durability, mechanical reliability, hemodynamic effectiveness, and biocompatibility has been satisfactory. Demonstration of long-term (2-year) effectiveness in supporting the circulation is the ultimate goal.

Driveline infections in left ventricular assist devices: implications for destination therapy.

PubMed

Sharma, Vikas; Deo, Salil V; Stulak, John M; Durham, Lucian A; Daly, Richard C; Park, Soon J; Baddour, Larry M; Mehra, Kashish; Joyce, Lyle D

2012-11-01

Infection is one of the major limitations to successful long-term support after ventricular assist device implantation. There are limited data specifically examining the incidence and predictors of driveline infections (DLI), with a changing treatment paradigm toward destination therapy (DT) and longer duration of support. Between January 2007 and 2011, 143 patients underwent HeartMate II (Thoratec, Pleasanton, CA) implantation, with 87 (61%) as DT. Driveline maintenance strategy included sterile dressing changes with chlorhexidine and saline application, without prophylactic oral antibiotics. DLI developed in 18 patients (12%) at a median of 182 days (range, 26 to 1,138 days) after implantation, among which 12 (66%) were from the DT cohort. Infections were superficial in 15 (82%) and deep in 3 (18%). Trauma was documented in 6 patients (33%). Seven patients (38%) needed readmission for DLI. Surgical debridement was needed in 3 (17%). All patients were managed successfully, without the need for device explantation or urgent cardiac transplantation. No patient required continuous antibiotic prophylaxis after the infection subsided. Risk factor analysis identified duration of support as the only independent predictor of infection (mean. 600 vs 390 days; p = 0.03). The odds of having a DLI rose by 4% for every month of support. Longer duration of support significantly increased the risk of DLI and hence increased the risk of DLI in patients with DT. DLI may be successfully managed with antibiotics and local wound care. Most of the infections were superficial, and progression to deep pocket or pump infection is rare in our experience. Copyright © 2012 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

A numerical method to enhance the performance of a cam-type electric motor-driven left ventricular assist device.

PubMed

Huang, Huan; Yang, Ming; Lu, Cunyue; Xu, Liang; Zhuang, Xiaoqi; Meng, Fan

2013-10-01

Pulsatile left ventricular assist devices (LVADs) driven by electric motors have been widely accepted as a treatment of heart failure. Performance enhancement with computer assistance for this kind of LVAD has seldom been reported. In this article, a numerical method is proposed to assist the design of a cam-type pump. The method requires an integrated model of an LVAD system, consisting of a motor, a transmission mechanism, and a cardiovascular circulation. Performance indices, that is, outlet pressure, outlet flow, and pump efficiency, were used to select the best cam profile from six candidates. A prototype pump connected to a mock circulatory loop (MCL) was used to calibrate the friction coefficient of the cam groove and preliminarily evaluate modeling accuracy. In vitro experiments show that the mean outlet pressure and flow can be predicted with high accuracy by the model, and gross geometries of the measurements can also be reproduced. Simulation results demonstrate that as the total peripheral resistance (TPR) is fixed at 1.1 mm Hg.s/mL, the two-cycle 2/3-rise profile is the best. Compared with other profiles, the maximum increases of pressure and flow indices are 75 and 76%, respectively, and the maximum efficiency increase is over 51%. For different TPRs (0.5∼1.5 mm Hg.s/mL) and operation intervals (0.1∼0.4 s) in counterpulsation, the conclusion is also acceptable. © 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation.

Development of a radial ventricular assist device using numerical predictions and experimental haemolysis.

PubMed

Carswell, Dave; Hilton, Andy; Chan, Chris; McBride, Diane; Croft, Nick; Slone, Avril; Cross, Mark; Foster, Graham

2013-08-01

The objective of this study was to demonstrate the potential of Computational Fluid Dynamics (CFD) simulations in predicting the levels of haemolysis in ventricular assist devices (VADs). Three different prototypes of a radial flow VAD have been examined experimentally and computationally using CFD modelling to assess device haemolysis. Numerical computations of the flow field were computed using a CFD model developed with the use of the commercial software Ansys CFX 13 and a set of custom haemolysis analysis tools. Experimental values for the Normalised Index of Haemolysis (NIH) have been calculated as 0.020 g/100 L, 0.014 g/100 L and 0.0042 g/100 L for the three designs. Numerical analysis predicts an NIH of 0.021 g/100 L, 0.017 g/100 L and 0.0057 g/100 L, respectively. The actual differences between experimental and numerical results vary between 0.0012 and 0.003 g/100 L, with a variation of 5% for Pump 1 and slightly larger percentage differences for the other pumps. The work detailed herein demonstrates how CFD simulation and, more importantly, the numerical prediction of haemolysis may be used as an effective tool in order to help the designers of VADs manage the flow paths within pumps resulting in a less haemolytic device. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Outcomes for Patients With Diabetes After Continuous-Flow Left Ventricular Assist Device Implantation.

PubMed

Vest, Amanda R; Mistak, Stanley M; Hachamovitch, Rory; Mountis, Maria M; Moazami, Nader; Young, James B

2016-10-01

Diabetes mellitus (DM) is a risk factor for mortality among patients with heart failure as well as for patients who undergo cardiothoracic surgery. However it is unknown whether DM is associated with increased mortality or major complications during continuous-flow left ventricular assist device (CF-LVAD) support. We retrospectively reviewed 300 consecutive adults who received CF-LVADs at a single center in the years 2006-2013; 129 patients had DM before LVAD, as defined by American Diabetes Association criteria (HbA1c ≥6.5% and/or taking DM medications). Compared with the non-DM group, DM patients were older, with a higher pre-LVAD body mass index, more ischemic heart failure etiology, and higher pre-LVAD creatinine. Ninety-three patients died on LVAD support, 43 with DM and 50 without DM (P = .4526). After control for 9 covariates in a Cox proportional hazards model, DM was unassociated with all-cause mortality (hazard ratio 0.883, 95% confidence interval 0.571-1.366; P = .5768). Diabetes was also unassociated with the adverse event end points of stroke/transient ischemic attack, intracerebral hemorrhage, pump thrombosis, and device-related infections. Diabetes is common in LVAD recipients (43% of the present cohort) but does not increase mortality or rates of major adverse events during CF-LVAD support. Copyright © 2016 Elsevier Inc. All rights reserved.

Palliative medicine consultation for preparedness planning in patients receiving left ventricular assist devices as destination therapy.

PubMed

Swetz, Keith M; Freeman, Monica R; AbouEzzeddine, Omar F; Carter, Kari A; Boilson, Barry A; Ottenberg, Abigale L; Park, Soon J; Mueller, Paul S

2011-06-01

To assess the benefit of proactive palliative medicine consultation for delineation of goals of care and quality-of-life preferences before implantation of left ventricular assist devices as destination therapy (DT). We retrospectively reviewed the cases of patients who received DT between January 15, 2009, and January 1, 2010. Of 19 patients identified, 13 (68%) received proactive palliative medicine consultation. Median time of palliative medicine consultation was 1 day before DT implantation (range, 5 days before to 16 days after). Thirteen patients (68%) completed advance directives. The DT implantation team and families reported that preimplantation discussions and goals of care planning made postoperative care more clear and that adverse events were handled more effectively. Currently, palliative medicine involvement in patients receiving DT is viewed as routine by cardiac care specialists. Proactive palliative medicine consultation for patients being considered for or being treated with DT improves advance care planning and thus contributes to better overall care of these patients. Our experience highlights focused advance care planning, thorough exploration of goals of care, and expert symptom management and end-of-life care when appropriate.

Magnetic suspension of the rotor of a ventricular assist device of mixed flow type.

PubMed

Horikawa, Oswaldo; de Andrade, Aron José Pazin; da Silva, Isaías; Bock, Eduardo Guy Perpetuo

2008-04-01

This work presents results of preliminary studies concerning application of magnetic bearing in a ventricular assist device (VAD) being developed by Dante Pazzanese Institute of Cardiology-IDPC (São Paulo, Brazil). The VAD-IDPC has a novel architecture that distinguishes from other known VADs. In this, the rotor has a conical geometry with spiral impellers, showing characteristics that are intermediate between a centrifugal VAD and an axial VAD. The effectiveness of this new type of blood pumping principle was showed by tests and by using it in heart surgery for external blood circulation. However, the developed VAD uses a combination of ball bearings and mechanical seals, limiting the life for some 10 h, making impossible its long-term use or its use as an implantable VAD. As a part of development of an implantable VAD, this work aims at the replacement of ball bearings by a magnetic bearing. The most important magnetic bearing principles are studied and the magnetic bearing developed by Escola Politécnica of São Paulo University (EPUSP-MB) is elected because of its very simple architecture. Besides presenting the principle of the EPUSP-MB, this work presents one possible alternative for applying the EPUSP-MB in the IDPC-VAD.

Performance of a continuous flow ventricular assist device: magnetic bearing design, construction, and testing.

PubMed

Allaire, P; Hilton, E; Baloh, M; Maslen, E; Bearnson, G; Noh, D; Khanwilkar, P; Olsen, D

1998-06-01

A new centrifugal continuous flow ventricular assist device, the CFVAD III, which is fully magnetic bearing suspended, has been developed. It has only one moving part (the impeller), has no contact (magnetic suspension), is compact, and has minimal heating. A centrifugal impeller of 2 inch outer diameter is driven by a permanent magnet brushless DC motor. This paper discusses the design, construction, testing, and performance of the magnetic bearings in the unit. The magnetic suspension consists of an inlet side magnetic bearing and an outlet side magnetic bearing, each divided into 8 pole segments to control axial and radial displacements as well as angular displacements. The magnetic actuators are composed of several different materials to minimize size and weight while having sufficient load capacity to support the forces on the impeller. Flux levels in the range of 0.1 T are employed in the magnetic bearings. Self sensing electronic circuits (without physical sensors) are employed to determine the impellar position and provide the feedback control signal needed for the magnetic bearing control loops. The sensors provide position sensitivity of approximately 0.025 mm. A decentralized 5 axis controller has been developed using modal control techniques. Proportional integral derivative controls are used for each axis to levitate the magnetically supported impeller.

Patient-Reported Health-Related Quality of Life Is a Predictor of Outcomes in Ambulatory Heart Failure Patients Treated With Left Ventricular Assist Device Compared With Medical Management: Results From the ROADMAP Study (Risk Assessment and Comparative Effectiveness of Left Ventricular Assist Device and Medical Management).

PubMed

Stehlik, Josef; Estep, Jerry D; Selzman, Craig H; Rogers, Joseph G; Spertus, John A; Shah, Keyur B; Chuang, Joyce; Farrar, David J; Starling, Randall C

2017-06-01

The prospective observational ROADMAP study (Risk Assessment and Comparative Effectiveness of Left Ventricular Assist Device and Medical Management) demonstrated that ambulatory advanced heart failure patients selected for left ventricular assist device (LVAD) were more likely to be alive at 1 year on original therapy with ≥75-m improvement in 6-minute walk distance compared with patients assigned to optimal medical management. Whether baseline health-related quality of life (hrQoL) resulted in a heterogeneity of this treatment benefit is unknown. Patient-reported hrQoL was assessed with EuroQol questionnaire and visual analogue scale (VAS). We aimed to identify predictors of event-free survival and survival with acceptable hrQoL (VAS≥60). LVAD patients had significant improvement in 3 of 5 EuroQol dimensions ( P <0.05), but no significant changes were observed with optimal medical management. Among patients with baseline VAS<55, survival on original treatment was lower for optimal medical management patients compared with those assigned to LVAD (58±7% versus 82±5%; P =0.004). No such difference was seen if baseline VAS was ≥55 (70±7% versus 75±9%; P =0.79). Survival on original therapy with acceptable quality of life was also more likely with LVAD versus optimal medical management if baseline VAS was <55, whereas outcomes in patients with higher baseline VAS scores were similar regardless of treatment assignment ( P =0.046 for treatment arm and baseline VAS interaction). LVAD therapy resulted in improvement of patient health status in heart failure patients with low self-reported hrQoL, but not in patients with acceptable quality of life at the time of LVAD implantation. Patient-reported hrQoL should be integrated into decision making concerning the use and timing of LVAD therapy in heart failure patients who are symptom limited but remain ambulatory. URL: http://www.ClinicalTrials.gov. Unique identifier: NCT01452802. © 2017 American Heart Association

NASA USAID Memorandum of Understanding

NASA Image and Video Library

2011-04-25

USAID Administrator Rajiv Shahspeaks prior to signing a five-year memorandum of understanding with NASA, Monday, April 25, 2011, at NASA Headquarters in Washington. The agreement formalizes ongoing agency collaborations that use Earth science data to address developmental challenges, and to assist in disaster mitigation and humanitarian responses. The agreement also encourages NASA and USAID to apply geospatial technologies to solve development challenges affecting the United States and developing countries. Photo Credit: (NASA/Paul E. Alers)

NASA USAID Memorandum of Understanding

NASA Image and Video Library

2011-04-25

USAID Administrator Rajiv Shah, left, and NASA Administrator Charles Bolden sign a five-year memorandum of understanding, Monday, April 25, 2011, at NASA Headquarters in Washington. The agreement formalizes ongoing agency collaborations that use Earth science data to address developmental challenges, and to assist in disaster mitigation and humanitarian responses. The agreement also encourages NASA and USAID to apply geospatial technologies to solve development challenges affecting the United States and developing countries. Photo Credit: (NASA/Paul E. Alers)

NASA USAID Memorandum of Understanding

NASA Image and Video Library

2011-04-25

USAID Administrator Rajiv Shah speaks prior to signing a five-year memorandum of understanding with NASA, Monday, April 25, 2011, at NASA Headquarters in Washington. The agreement formalizes ongoing agency collaborations that use Earth science data to address developmental challenges, and to assist in disaster mitigation and humanitarian responses. The agreement also encourages NASA and USAID to apply geospatial technologies to solve development challenges affecting the United States and developing countries. Photo Credit: (NASA/Paul E. Alers)

Non-Invasive Mapping of Intraventricular Flow Patterns in Patients Treated with Left Ventricular Assist Devices

NASA Astrophysics Data System (ADS)

Miramontes, Marissa; Rossini, Lorenzo; Braun, Oscar; Brambatti, Michela; Almeida, Shone; Mizeracki, Adam; Martinez-Legazpi, Pablo; Benito, Yolanda; Bermejo, Javier; Kahn, Andrew; Adler, Eric; Del Álamo, Juan C.

2017-11-01

In heart failure patients, left ventricular (LV) assist devices (LVADs) decrease mortality and improve quality of life. We hypothesize echo color Doppler velocimetry (echo-CDV), an echocardiographic flow mapping modality, can non-invasively characterize the effect of LVAD support, optimize the device, thereby decreasing the stoke rate present in these patients. We used echo-CDV to image LV flow at baseline LVAD speed and during a ramp test in LVAD patients (Heartmate II, N =10). We tracked diastolic vortices and mapped blood stasis and cumulative shear. Compared to dilated cardiomyopathy (DCM) patients without LVADs, the flow had a less prominent diastolic vortex ring, and transited directly from mitral valve to cannula. Residence time and shear were significantly lower compared to healthy controls and DCMs. Aortic regurgitation and a large LV vortex presence or a direct mitral jet towards the cannula affected blood stasis region location and size. Flow patterns, residence time and shear depended on LV geometry, valve function and LVAD speed in a patient specific manner. This new methodology could be used with standard echo, hemodynamics and clinical information to find the flow optimizing LAVD setting minimizing stasis for each patient.

A Novel Mean-Value Model of the Cardiovascular System Including a Left Ventricular Assist Device.

PubMed

Ochsner, Gregor; Amacher, Raffael; Schmid Daners, Marianne

2017-06-01

Time-varying elastance models (TVEMs) are often used for simulation studies of the cardiovascular system with a left ventricular assist device (LVAD). Because these models are computationally expensive, they cannot be used for long-term simulation studies. In addition, their equilibria are periodic solutions, which prevent the extraction of a linear time-invariant model that could be used e.g. for the design of a physiological controller. In the current paper, we present a new type of model to overcome these problems: the mean-value model (MVM). The MVM captures the behavior of the cardiovascular system by representative mean values that do not change within the cardiac cycle. For this purpose, each time-varying element is manually converted to its mean-value counterpart. We compare the derived MVM to a similar TVEM in two simulation experiments. In both cases, the MVM is able to fully capture the inter-cycle dynamics of the TVEM. We hope that the new MVM will become a useful tool for researchers working on physiological control algorithms. This paper provides a plant model that enables for the first time the use of tools from classical control theory in the field of physiological LVAD control.

Comparative analysis of ventricular assist devices (POLVAD and POLVAD_EXT) based on multiscale FEM model.

PubMed

Milenin, Andrzej; Kopernik, Magdalena

2011-01-01

The prosthesis - pulsatory ventricular assist device (VAD) - is made of polyurethane (PU) and biocompatible TiN deposited by pulsed laser deposition (PLD) method. The paper discusses the numerical modelling and computer-aided design of such an artificial organ. Two types of VADs: POLVAD and POLVAD_EXT are investigated. The main tasks and assumptions of the computer program developed are presented. The multiscale model of VAD based on finite element method (FEM) is introduced and the analysis of the stress-strain state in macroscale for the blood chamber in both versions of VAD is shown, as well as the verification of the results calculated by applying ABAQUS, a commercial FEM code. The FEM code developed is based on a new approach to the simulation of multilayer materials obtained by using PLD method. The model in microscale includes two components, i.e., model of initial stresses (residual stress) caused by the deposition process and simulation of active loadings observed in the blood chamber of POLVAD and POLVAD_EXT. The computed distributions of stresses and strains in macro- and microscales are helpful in defining precisely the regions of blood chamber, which can be defined as the failure-source areas.

Discontinuation of antithrombotic therapy for a year or more in patients with continuous-flow left ventricular assist devices.

PubMed

Pereira, Naveen L; Chen, Dong; Kushwaha, Sudhir S; Park, Soon J

2010-10-01

The recommended anticoagulation regimen during continuous-flow axial left ventricular assist device (LVAD) support is aspirin and warfarin with a targeted international normalized ratio of 2.0-3.0. We report two patients in whom recurrent gastrointestinal bleeding during LVAD support necessitated discontinuation of this anti-thrombotic regimen for a year or more. Despite this, neither patients developed thrombotic complications during 29 patient-months of follow-up. An acquired von Willebrand factor (VWF) abnormality reflected by the absence or decreased abundance of the highest molecular weight multimers was demonstrated in both patients. The gold standard test for platelet function, light transmission platelet aggregometry was measured in one patient and was normal, indicative that the predominant abnormality in the coagulation profile of these patients is an acquired VWF syndrome. Clinical trials are required to address the question whether it is safe to discontinue anticoagulation in LVAD patients with acquired VWF abnormalities.

Surgical ablation of ventricular tachycardia secondary to congenital ventricular septal aneurysm.

PubMed

Graffigna, A; Minzioni, G; Ressia, L; Vigano, M

1994-04-01

Three patients underwent surgical ablation for ventricular tachycardia resulting from an aneurysm of the membranous portion of the ventricular septum. Two patients had a definite history of cardiac murmur during infancy, and one of them was found at the time of operation to have a left-to-right shunt through the apex of the aneurysm. The earliest ventricular activation sites were located around the neck of the aneurysm and were ablated in 1 patient by encircling the endocardial ventriculotomy and by cryoablation in the remaining 2. After focus resection had been completed, aneurysm resection and ventricular septal reconstruction were performed. All patients were alive and free of ventricular tachycardia and did not need medication as of 61, 66, and 88 months postoperatively. Spontaneous closure of a ventricular septal defect may lead to the formation of an aneurysm in the ventricular septum that may sustain ventricular tachycardias. Such arrhythmias can be effectively treated using electrically guided surgical techniques.

Women's History Month at NASA

NASA Image and Video Library

2011-03-14

Valerie Jarrett, senior advisor and assistant to the president for Public Engagement and Intergovernmental Affairs for the Obama administration, speaks at a Women's History Month event at NASA Headquarters, Wednesday, March 16, 2011 in Washington. The event entitled Women Inspiring the Next Generation to Reveal the Unknown is a joint venture with NASA and the White House Council on Women and Girls. Photo Credit: (NASA/Carla Cioffi)

NASA USAID Memorandum of Understanding

NASA Image and Video Library

2011-04-25

USAID Administrator Rajiv Shah, left, and NASA Administrator Charles Bolden shake hands after signing a five-year memorandum of understanding, Monday, April 25, 2011, at NASA Headquarters in Washington. The agreement formalizes ongoing agency collaborations that use Earth science data to address developmental challenges, and to assist in disaster mitigation and humanitarian responses. The agreement also encourages NASA and USAID to apply geospatial technologies to solve development challenges affecting the United States and developing countries. Photo Credit: (NASA/Paul E. Alers)

14 CFR 1212.701 - Assistant Deputy Administrator.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Assistant Deputy Administrator. 1212.701 Section 1212.701 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PRIVACY ACT-NASA REGULATIONS NASA Authority and Responsibilities § 1212.701 Assistant Deputy Administrator. The Assistant...

14 CFR 1212.701 - Assistant Deputy Administrator.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true Assistant Deputy Administrator. 1212.701 Section 1212.701 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PRIVACY ACT-NASA REGULATIONS NASA Authority and Responsibilities § 1212.701 Assistant Deputy Administrator. The Assistant...

Melding a High-Risk Patient for Continuous Flow Left Ventricular Assist Device into a Low-Risk Patient.

PubMed

Amione-Guerra, Javier; Cruz-Solbes, Ana S; Gonzalez Bonilla, Hilda; Estep, Jerry D; Guha, Ashrith; Bhimaraj, Arvind; Suarez, Erik E; Bruckner, Brian A; Torre-Amione, Guillermo; Park, Myung H; Trachtenberg, Barry H

The model for end-stage liver disease (MELD) has been used as a predictor of mortality after left ventricular assist device (LVAD) placement. However, improvement or worsening of MELD and how those changes affect outcomes is unknown. We performed a retrospective analysis of 244 patients implanted with a continuous flow (CF) LVAD. Patients were dichotomized at admission into low- or high-risk categories using a cutoff of MELD ≥ 19, and they were reclassified at day of implant forming four groups: Group LL (low to low, remained low risk), LH (low to high, worsened to high risk), HH (high to high, remained high risk), and HL (high to low, improved to low risk). Patients who improved to a low risk (group HL) had the same 1 year survival as those that remained low risk (group LL; 80% vs. 77%; p = 0.6). However, patients who were initially classified as low risk and worsened to a high risk (group LH) had a survival that was worse than those that were consistently high risk (group HH; 55% vs. 10%; p = 0.01). Model for end-stage liver disease reclassification after adjusting for commonly attributed risk factors remained an independent predictor for mortality, including patients classified as Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) 1 and 2. In conclusion, our MELD score reclassification is an independent and powerful predictor of mortality in patients undergoing LVAD implantation.

Sex and intimacy among patients with implantable left-ventricular assist devices.

PubMed

Marcuccilli, Linda; Casida, Jesus Jessie; Peters, Rosalind M; Wright, Susan

2011-01-01

Left-ventricular assist devices (LVADs) sustain and improve the quality of life of people living with an advanced stage of heart failure. Past research focused on the development and advancement of LVAD technology, complications, and survival rates. Limited research addressed the psychosocial aspects of living with an LVAD, yet research related to sexual functioning and intimacy is lacking. The purpose of this study was to explore and describe sex and intimacy among adults living with an LVAD. We used an interpretive phenomenological study to explore the experiences of adults living with a long-term implantable LVAD, including the effect of the LVAD on their intimate and sexual functioning. Semistructured interviews were conducted with 7 men and 2 women, 31 to 70 years of age, who had lived with the LVAD at home for at least 3 months. Interviews were audiorecorded and transcribed. The wholistic and selective approach by van Manen (Researching Lived Experience: Human Science for an Action Sensitive Pedagogy. Albany, NY: SUNY Press; 1990) guided the analysis and interpretation of the transcribed interviews. Data were organized and coded into words and phrases using qualitative software. Three themes emerged from the data: (a) improved sexual relations with LVAD, (b) sexual adjustment, and (c) nonsexual intimacy. The themes identified were consistent with the concept of normalcy from the theory of self-care. Participants reported that as the LVAD improved their overall health, their sexual functioning also improved. Participants also reported an increased sense of connectedness and intimacy with their partners even in the absence of sexual intercourse. Participants discussed ways in which they continued to develop intimate relationships even in the presence of limitations in structural and functional integrity. The knowledge derived from this study can be used as a guide for healthcare providers in counseling LVAD recipients on psychosocial and sexual health essential

Impact of 30 Day Readmission After Left Ventricular Assist Device Implantation.

PubMed

Gupta, Saurabh; Cogswell, Rebecca J; Roy, Samit S; Spratt, John R; Liao, Kenneth K; Martin, Cindy M; John, Ranjit

2018-05-07

Early readmission (within 30 days) after left ventricular assist device (LVAD) implantation might be a marker for increased mortality. We retrospectively reviewed the records of 277 adults who underwent continuous-flow LVAD implantation from 2005 through 2015 at our institution. The baseline characteristics of patients who were (versus were not) readmitted within 30 days after LVAD implantation were compared. To assess the impact of 30 day readmission on long-term survival, we used multivariate Cox regression. We also compared the cardiac transplant rate between the two groups. Of the 277 patients, 217 (78.3%) underwent LVAD implantation as a bridge-to-transplant; 76 (27.4%) of the 277 were readmitted within 30 days. The most common reason for readmission was volume overload (23.6%), followed by gastrointestinal bleeding (15.8%). Male gender, previous smoking, a higher baseline creatinine level, higher Model for End Stage Liver Disease Excluding INR (MELD-XI) score, and postoperative gastrointestinal bleeding or stroke were each associated with 30 day readmission. In our final multivariate model, increased mortality was also associated with 30 day readmission (hazard ratio, 1.60; 95% confidence interval, 1.1-2.5). Among the 217 bridge-to-transplant patients, the cardiac transplant rate was similar between the two groups: 18.7 transplants per patient-year among those who were readmitted within 30 days versus 19.7 transplants per patient-year among those who were not (p = 0.26). Among our study patients, 30 day readmission after LVAD implantation was frequent and was associated with increased mortality. It is currently unclear whether the general health of those patients was a factor and whether efforts to reduce 30 day readmission would favorably affect longer-term patient outcomes.

Secondary ventricular fibrillation or pulseless ventricular tachycardia during cardiac arrest and epinephrine dosing.

PubMed

Straznitskas, Andrew D; Wong, Sylvia; Kupchik, Nicole; Carlbom, David

2015-05-01

Development of ventricular fibrillation or pulseless ventricular tachycardia after an initial rhythm of pulseless electrical activity or asystole is associated with significantly increased cardiac arrest mortality. To examine differences in epinephrine administration during cardiac arrest between patients who had a secondary ventricular fibrillation or ventricular tachycardia develop and patients who did not. Data were collected for 2 groups of patients with in-hospital cardiac arrest and an initial rhythm of pulseless electrical activity or asystole: those who had a secondary ventricular fibrillation or ventricular tachycardia develop (cases) and those who did not (controls). Dosing of epinephrine during cardiac arrest and other variables were compared between cases and controls. Of the 215 patients identified with an initial rhythm of pulseless electrical activity or asystole, 51 (23.7%) had a secondary ventricular fibrillation or ventricular tachycardia develop. Throughout the total duration of arrest, including periods of return of spontaneous circulation, the dosing interval for epinephrine in patients who had a secondary ventricular fibrillation or ventricular tachycardia develop was 1 mg every 3.4 minutes compared with 1 mg every 5 minutes in controls (P= .001). For the total duration of pulselessness, excluding periods of return of spontaneous circulation during the arrest, the dosing interval for epinephrine in patients who had a secondary ventricular fibrillation or ventricular tachycardia develop was 1 mg every 3.1 minutes versus 1 mg every 4.3 minutes in controls (P= .001). More frequent administration of epinephrine during cardiac arrest is associated with development of secondary ventricular fibrillation or ventricular tachycardia. ©2015 American Association of Critical-Care Nurses.

General and acute care surgical procedures in patients with left ventricular assist devices.

PubMed

Arnaoutakis, George J; Bittle, Gregory J; Allen, Jeremiah G; Weiss, Eric S; Alejo, Jennifer; Baumgartner, William A; Shah, Ashish S; Wolfgang, Christopher L; Efron, David T; Conte, John V

2014-04-01

Left ventricular assist devices (LVADs) have become common as a bridge to heart transplant as well as destination therapy. Acute care surgical (ACS) problems in this population are prevalent but remain ill-defined. Therefore, we reviewed our experience with ACS interventions in LVAD patients. A total of 173 patients who received HeartMate(®) XVE or HeartMate(®) II (HMII) LVADs between December 2001 and March 2010 were studied. Patient demographics, presentation of ACS problem, operative intervention, co-morbidities, transplantation, complications, and survival were analyzed. A total of 47 (27 %) patients underwent 67 ACS procedures at a median of 38 days after device implant (interquartile range 15-110), with a peri-operative mortality rate of 5 % (N = 3). Demographics, device type, and acuity were comparable between the ACS and non-ACS groups. A total of 21 ACS procedures were performed emergently, eight were urgent, and 38 were elective. Of 29 urgent and emergent procedures, 28 were for abdominal pathology. In eight patients, the cause of the ACS problem was related to LVADs or anticoagulation. Cumulative survival estimates revealed no survival differences if patients underwent ACS procedures (p = 0.17). Among HMII patients, transplantation rates were unaffected by an ACS intervention (p = 0.2). ACS problems occur frequently in LVAD patients and are not associated with adverse outcomes in HMII patients. The acute care surgeon is an integral member of a comprehensive approach to effective LVAD management.

Design of a miniature implantable left ventricular assist device using CAD/CAM technology.

PubMed

Okamoto, Eiji; Hashimoto, Takuya; Mitamura, Yoshinori

2003-01-01

In this study, we developed a new miniature motor-driven pulsatile left ventricular assist device (LVAD) for implantation into a Japanese patient of average build by means of computer-aided design and manufacturing (CAD/CAM) technology. A specially designed miniature ball-screw and a high-performance brushless DC motor were used in an artificial heart actuator to allow miniaturization. A blood pump chamber (stroke volume 55 ml) and an inflow and outflow port were designed by computational fluid dynamics (CFD) analysis. The geometry of the blood pump was evaluated using the value of index of pump geometry (IPG) = (Reynolds shear stress) x (occupied volume) as a quantitative index for optimization. The calculated value of IPG varied from 20.6 Nm to 49.1 Nm, depending on small variations in pump geometry. We determined the optimum pump geometry based on the results of quantitative evaluation using IPG and qualitative evaluation using the flow velocity distribution with blood flow tracking. The geometry of the blood pump that gave lower shear stress had more optimum spiral flow around the diaphragm-housing (D-H) junction. The volume and weight of the new LVAD, made of epoxy resin, is 309 ml and 378 g, but further miniaturization will be possible by improving the geometry of both the blood pump and the back casing. Our results show that our new design method for an implantable LVAD using CAD/CAM promises to improve blood compatibility with greater miniaturization.

Shape optimization of pulsatile ventricular assist devices using FSI to minimize thrombotic risk

NASA Astrophysics Data System (ADS)

Long, C. C.; Marsden, A. L.; Bazilevs, Y.

2014-10-01

In this paper we perform shape optimization of a pediatric pulsatile ventricular assist device (PVAD). The device simulation is carried out using fluid-structure interaction (FSI) modeling techniques within a computational framework that combines FEM for fluid mechanics and isogeometric analysis for structural mechanics modeling. The PVAD FSI simulations are performed under realistic conditions (i.e., flow speeds, pressure levels, boundary conditions, etc.), and account for the interaction of air, blood, and a thin structural membrane separating the two fluid subdomains. The shape optimization study is designed to reduce thrombotic risk, a major clinical problem in PVADs. Thrombotic risk is quantified in terms of particle residence time in the device blood chamber. Methods to compute particle residence time in the context of moving spatial domains are presented in a companion paper published in the same issue (Comput Mech, doi: 10.1007/s00466-013-0931-y, 2013). The surrogate management framework, a derivative-free pattern search optimization method that relies on surrogates for increased efficiency, is employed in this work. For the optimization study shown here, particle residence time is used to define a suitable cost or objective function, while four adjustable design optimization parameters are used to define the device geometry. The FSI-based optimization framework is implemented in a parallel computing environment, and deployed with minimal user intervention. Using five SEARCH/ POLL steps the optimization scheme identifies a PVAD design with significantly better throughput efficiency than the original device.

Endoscopic Findings and Clinical Outcomes in Ventricular Assist Device Recipients with Gastrointestinal Bleeding

PubMed Central

Elmunzer, B. Joseph; Padhya, Kunjali T.; Lewis, Jason J.; Rangnekar, Amol S.; Saini, Sameer D.; Eswaran, Shanti L.; Scheiman, James M.; Pagani, Francis D.; Haft, Jonathan W.; Waljee, Akbar K.

2015-01-01

Background Gastrointestinal bleeding (GIB) is an important clinical problem in recipients of ventricular assist devices (VAD), although data pertaining to the endoscopic evaluation and management of this complication are limited in the medical literature. Aims We sought to identify the most common endoscopic findings in VAD recipients with GIB, and to better define the diagnostic and therapeutic utility of endosopy for this patient population. Methods Twenty-six subjects with VAD and overt GIB were retrospectively identified. Clinical and endoscopic data were abstracted for each subject on to standardized forms in duplicate and independent fashion. Raw data and descriptive statistics were reported. Results Non-peptic vascular lesions were the most common cause of GIB. A definitive cause of bleeding was identified by endoscopy in almost 60% of subjects. Endoscopic hemostasis was achieved in 14/15 patients in whom bleeding did not stop spontaneously. Rebleeding occurred in 50% of subjects and was successfully retreated or stopped spontaneously in all cases. Colonoscopy did not establish a definitive diagnosis or deliver hemostatic therapy in any case. Conclusions Vascular malformations account for the overwhelming majority of bleeding lesions in VAD patients with GIB. Endoscopy seems to be a safe and effective tool for diagnosing, risk stratifying, and treating this patient population, although multiple endoscopies may be necessary before therapeutic success, and the incidence of rebleeding is high. A prospective multi-center registry is necessary to establish evidence-based management algorithms for VAD recipients with GIB. PMID:21792619

A conceptual definition of quality of life with a left ventricular assist device: results from a qualitative study.

PubMed

Sandau, Kristin E; Hoglund, Barbara A; Weaver, Carrie E; Boisjolie, Charlene; Feldman, David

2014-01-01

To develop a conceptual definition of quality of life (QoL) with a left ventricular assist device (LVAD). Conceptual and operational definitions of QoL with an LVAD are lacking. A grounded theory method was used. Adult, outpatient LVAD recipients (n = 11) participated twice in individual or paired interviews. A conceptual definition of QoL while living with an LVAD was established as: "Being well enough to do and enjoy day-to-day activities that are important to me." Participants described 5 important life domains consistent with QoL literature: physical, emotional, social, cognitive, and spiritual/meaning. However, participants identified unique concerns not addressed by generic or heart failure disease specific measures typically used in the LVAD population. Existing generic and heart-failure specific QoL measures are not adequate for understanding QoL among LVAD patients. Cognition and spiritual/meaning domains were significant; these need inclusion for comprehensive QoL assessment in the LVAD population. Copyright © 2014 Elsevier Inc. All rights reserved.

Postoperative B-Type Natriuretic Peptide as Predictor for Postoperative Outcomes in Patients Implanted With Left Ventricular Assist Devices.

PubMed

Yost, Gardner; Bhat, Geetha; Pappas, Patroklos; Tatooles, Antone

2018-04-18

Brain natriuretic peptide (BNP) is a cardiac neurohormone known to correlate with left ventricular (LV) dilation, decreased contractility, and increased stiffness. Consequently, BNP has been used as a prognostic tool to assess the degree of LV unloading for patients supported by continuous-flow LV assist devices (LVADs). We assessed the prognostic value of changes in BNP in the 2 weeks after LVAD implantation. This retrospective study analyzed laboratory findings and outcomes of 189 LVAD patients. Patients were separated into two groups based on whether serum BNP levels had improved from preoperative levels by postoperative day 14. Group 1 had improvement in BNP levels, whereas group 2 had no improvement or worsening in BNP. There were no significant differences between the groups in age, gender, race, body mass index, or comorbidities. Group 1 had preoperative BNP 1,125 ± 1,078.3 pg/dl and postoperative BNP 440.2 ± 267.7 pg/dl (ΔBNP = -693.09 ± 942.4 pg/dl), whereas group 2 had preoperative BNP 346.0 ± 309.1 pg/dl and postoperative BNP 631.57 ± 483.4 pg/dl (ΔBNP = 289.32 ± 329.7 pg/dl). Postoperative survival in group 2 was significantly worse than in group 1. Rates of right ventricular failure (RVF) were significantly higher in group 2 (group 1: 39%, group 2: 52.7%; p = 0.01). In most patients implanted with a LVAD, BNP improves significantly in the postoperative period as the LV is unloaded. Our results indicate that lack of improvement in postoperative BNP is associated with longer length of stay, increased rates of RVF, and is an independent risk factor for reduced postoperative survival.

Hemodynamic deterioration precedes onset of ventricular tachyarrhythmia after Heartmate II implantation.

PubMed

Yaksh, Ameeta; Kik, Charles; Knops, Paul; Zwiers, Korinne; van Ettinger, Maarten J B; Manintveld, Olivier C; de Wijs, Marcel C J; van der Kemp, Peter; Bogers, Ad J J C; de Groot, Natasja M S

2016-07-08

Early postoperative ventricular tachyarrhythmia (PoVT) after left ventricular assist device (LVAD) implantation are common and associated with higher mortality-rates. At present, there is no data on initiation of these PoVT and the role of alterations in cardiac hemodynamics. A LVAD was implanted in a patient with end-stage heart failure due to a ischemic cardiomyopathy. Alterations in cardiac rhythm and hemodynamics preceding PoVT-episodes during the first five postoperative days were examined by using continuous recordings of cardiac rhythm and various hemodynamic parameters. All PoVT (N=120) were monomorphic, most often preceded by short-long-short-sequences or regular SR and initiated by ventricular runs. Prior to PoVT, mean arterial pressure decreased; heart rate and ST-segments deviations increased. PoVT are caused by different underlying electrophysiological mechanisms. Yet, they are all monomorphic and preceded by hemodynamic deterioration due to myocardial ischemia.

Early trends in N-terminal pro-brain natriuretic peptide values after left ventricular assist device implantation for chronic heart failure.

PubMed

Hasin, Tal; Kushwaha, Sudhir S; Lesnick, Timothy G; Kremers, Walter; Boilson, Barry A; Schirger, John A; Clavell, Alfredo L; Rodeheffer, Richard J; Frantz, Robert P; Edwards, Brooks S; Pereira, Naveen L; Stulak, John M; Joyce, Lyle; Daly, Richard; Park, Soon J; Jaffe, Allan S

2014-10-15

Left ventricular assist devices (LVADs) acutely decrease left ventricular wall stress. Thus, early postoperative levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) should decrease. This study investigated postoperative changes in NT-proBNP levels, the parameters related to changes, and the possible association with complications by performing a retrospective analysis of changes in daily NT-proBNP (pg/ml) levels from admission to discharge both before and after LVAD implantation in a tertiary referral center. For 72 patients implanted with HeartMate II LVADs, baseline NT-proBNP levels were elevated at 3,943 ng/ml (interquartile range 1,956 to 12,964). Preoperative stabilization led to marked decreases in NT-proBNP. Levels peaked 3 days after surgery and subsequently decreased. Patients with complicated postoperative courses had higher early postoperative elevations. By discharge, NT-proBNP decreased markedly but was still 2.83 (1.60 to 5.76) times the age-based upper limit of normal. The 26% reduction in NT-proBNP between admission and discharge was due mostly to the preoperative reductions and not those induced by the LVAD itself. The decrease was not associated with decreases in LV volume. In conclusion, preoperative treatment reduces NT-proBNP values. The magnitude of early postoperative changes is related to the clinical course. Levels at discharge remain markedly elevated and similar to values after preoperative stabilization despite presumptive acute LV unloading. Copyright © 2014 Elsevier Inc. All rights reserved.

A compliant, banded outflow cannula for decreased afterload sensitivity of rotary right ventricular assist devices.

PubMed

Gregory, Shaun D; Schummy, Emma; Pearcy, Mark; Pauls, Jo P; Tansley, Geoff; Fraser, John F; Timms, Daniel

2015-02-01

Biventricular support with dual rotary ventricular assist devices (VADs) has been implemented clinically with restriction of the right VAD (RVAD) outflow cannula to artificially increase afterload and, therefore, operate within recommended design speed ranges. However, the low preload and high afterload sensitivity of these devices increase the susceptibility of suction events. Active control systems are prone to sensor drift or inaccurate inferred (sensor-less) data, therefore an alternative solution may be of benefit. This study presents the in vitro evaluation of a compliant outflow cannula designed to passively decrease the afterload sensitivity of rotary RVADs and minimize left-sided suction events. A one-way fluid-structure interaction model was initially used to produce a design with suitable flow dynamics and radial deformation. The resultant geometry was cast with different initial cross-sectional restrictions and concentrations of a softening diluent before evaluation in a mock circulation loop. Pulmonary vascular resistance (PVR) was increased from 50 dyne s/cm(5) until left-sided suction events occurred with each compliant cannula and a rigid, 4.5 mm diameter outflow cannula for comparison. Early suction events (PVR ∼ 300 dyne s/cm(5) ) were observed with the rigid outflow cannula. Addition of the compliant section with an initial 3 mm diameter restriction and 10% diluent expanded the outflow restriction as PVR increased, thus increasing RVAD flow rate and preventing left-sided suction events at PVR levels beyond 1000 dyne s/cm(5) . Therefore, the compliant, restricted outflow cannula provided a passive control system to assist in the prevention of suction events with rotary biventricular support while maintaining pump speeds within normal ranges of operation. Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Hybrid model analysis of intra-aortic balloon pump performance as a function of ventricular and circulatory parameters.

PubMed

Ferrari, Gianfranco; Khir, Ashraf W; Fresiello, Libera; Di Molfetta, Arianna; Kozarski, Maciej

2011-09-01

We investigated the effects of the intra-aortic balloon pump (IABP) on endocardial viability ratio (EVR), cardiac output (CO), end-systolic (V(es)) and end-diastolic (V(ed)) ventricular volumes, total coronary blood flow (TCBF), and ventricular energetics (external work [EW], pressure-volume area [PVA]) under different ventricular (E(max) and diastolic stiffness) and circulatory (arterial compliance) parameters. We derived a hybrid model from a computational model, which is based on merging computational and hydraulic submodels. The lumped parameter computational submodel consists of left and right hearts and systemic, pulmonary, and coronary circulations. The hydraulic submodel includes part of the systemic arterial circulation, essentially a silicone rubber tube representing the aorta, which contains a 40-mL IAB. EVR, CO, V(es), and V(ed), TCBF and ventricular energetics (EW, PVA) were analyzed against the ranges of left ventricular E(max) (0.3-0.5-1 mm Hg/cm(3)) and diastolic stiffness V(stiffness) (≈0.08 and ≈0.3 mm Hg/cm(3), obtained by changing diastolic stiffness constant) and systemic arterial compliance (1.8-2.5 cm(3)/mm Hg). All experiments were performed comparing the selected variables before and during IABP assistance. Increasing E(maxl) from 0.5 to 2 mm Hg/cm(3) resulted in IABP assistance producing lower percentage changes in the selected variables. The changes in ventricular diastolic stiffness strongly influence both absolute value of EVR and its variations during IABP (71 and 65% for lower and higher arterial compliance, respectively). V(ed) and V(es) changes are rather small but higher for lower E(max) and higher V(stiffness). Lower E(max) and higher V(stiffness) resulted in higher TCBF and CO during IABP assistance (∼35 and 10%, respectively). The use of this hybrid model allows for testing real devices in realistic, stable, and repeatable circulatory conditions. Specifically, the presented results show that IABP performance is dependent

Hydrodynamic endurance test of the prosthetic valve used in the various types of the ventricular assist device.

PubMed

Nitta, S; Yambe, T; Katahira, Y; Sonobe, T; Saijoh, Y; Naganuma, S; Akiho, H; Kakinuma, Y; Tanaka, M; Miura, M

1991-12-01

To evaluate the various basic designs of the pump chambers used in the ventricular assist devices (VADs), hydrodynamic endurance test was performed from the viewpoint of the durability of the prosthetic valves used in the VAD. For the hydrodynamic analysis, we designed three basic types of pump (sac type, diaphragm type, and pusher plate type) using the same material and having the same capacity and shape. Prosthetic valves in these VADs were tested from the standpoint of the water hammer effect, which affects the valve durability, to determine which pump design would be most durable as a prosthetic valve in the VAD. The water-hammer phenomenon was evaluated using the maximum pressure gradient (MPG) across the prosthetic valve in the moc circulatory loop. Maximum pump output was recorded when we used the diaphragm type model, and minimum MPG in the commonly used driving condition of the VAD were recorded when we used the sac type model. The results suggest that the sac type VAD model is the most durable design for the prosthetic value.

Arrhythmogenic Right Ventricular Cardiomyopathy in an Endurance Athlete Presenting with Ventricular Tachycardia and Normal Right Ventricular Function.

PubMed

Hedley, Jeffrey S; Al Mheid, Ibhar; Alikhani, Zoubin; Pernetz, Maria A; Kim, Jonathan H

2017-08-01

Arrhythmogenic right ventricular cardiomyopathy, a genetically inherited disease that results in fibrofatty replacement of normal cardiac myocytes, has been associated with sudden cardiac death in athletes. Long-term participation in endurance exercise hastens the development of both the arrhythmic and structural arrhythmogenic right ventricular cardiomyopathy phenotypes. We describe the unusual case of a 34-year-old, symptomatic, female endurance athlete who had arrhythmogenic right ventricular cardiomyopathy in the presence of a structurally normal right ventricle. Clinicians should be aware of this infrequent presentation when evaluating athletic patients who have ventricular arrhythmias and normal findings on cardiac imaging studies.

Exercise guidelines for inpatients following ventricular assist device placement: a systematic review of the literature.

PubMed

Scheiderer, Rachel; Belden, Courtney; Schwab, Darla; Haney, Casey; Paz, Jaime

2013-06-01

For patients with end-stage heart failure awaiting transplantation, lack of donor organs has created an increased need for alternatives such as left ventricular assist device (LVAD) implantation. The purpose of this study is to determine safe and effective exercise parameters for physical therapy in the acute care setting. A systematic literature review was conducted according to PRISMA guidelines using Sackett's Levels of Evidence to rate the evidence. Multiple databases were searched with inclusion criteria of: available in English, inpatient care up to 6 months postoperatively, description of intervention type and exercise parameters. no defined exercise parameters, outpatient treatment, infection post VAD, or palliative or hospice care post VAD. Six studies out of 1,291 articles met inclusion criteria. Common exercise parameters used were the Borg Rating of Perceived Exertion scale 11-13 (6-20 scale) or > 4 (0-10 scale), Dyspnea scale > 2 (0-4 scale) and > 5 (0-10 scale), mean arterial pressure (MAP) 70-95 mmHg, and LVAD flow > 3L/min. Levels of evidence ranged from case controlled to expert opinion. Current evidence on inpatient exercise parameters for patient's status post LVAD implantation is not sufficient to suggest definitive guidelines; however, these exercise parameters provide a reference for patient care.

Finite Element Analysis of Stresses Developed in the Blood Sac of a Left Ventricular Assist Device

PubMed Central

Haut Donahue, T. L.; Dehlin, W.; Gillespie, J.; Weiss, W.J.; Rosenberg, G.

2009-01-01

The goal of this research is to develop a 3D finite element (FE) model of a left ventricular assist device (LVAD) to predict stresses in the blood sac. The hyperelastic stress-strain curves for the segmented poly(ether polyurethane urea) blood sac were determined in both tension and compression using a servo-hydraulic testing system at various strain rates. Over the range of strain rates studied, the sac was not strain rate sensitive, however the material response was different for tension versus compression. The experimental tension and compression properties were used in a FE model that consisted of the pusher plate, blood sac and pump case. A quasi-static analysis was used to allow for nonlinearities due to contact and material deformation. The 3D FE model showed that blood sac stresses are not adversely affected by the location of the inlet and outlet ports of the device and that over the systolic ejection phase of the simulation the prediction of blood sac stresses from the full 3D model and an axisymmetric model are the same. Minimizing stresses in the blood sac will increase the longevity of the blood sac in vivo. PMID:19131267

Impact of Vice President Cheney on public interest in left ventricular assist devices and heart transplantation.

PubMed

Pandey, Ambarish; Abdullah, Kazeen; Drazner, Mark H

2014-05-01

Although celebrity illnesses attract a significant amount of media attention in the United States, there are few studies that have looked at how celebrity health conditions impact the awareness of the illness in the general population. Recently, Vice President Cheney underwent left ventricular assist device (LVAD) implantation and subsequently a cardiac transplant. The aim of this study was to determine whether there was evidence of increased interest in these 2 procedures as assessed by social media. We determined the relative frequency of Google searches for LVAD and heart transplantation from 2004 to 2013 using Google trends. We also counted the number of YouTube videos and Twitter messages posted monthly concerning LVADs over a 7-year time frame. There was a significant spike in the Google search interest for LVAD and heart transplantation in the month when Vice President Cheney underwent the respective procedure. Similarly, there was a large increase in YouTube videos and Twitter messages concerning LVADs shortly after he was implanted. In total, these data support the concept that a public figure's illness can significantly influence the public's interest in that condition and its associated therapies. Copyright © 2014 Elsevier Inc. All rights reserved.

The writers guide to NASA. [NASA Centers and public affairs contacts

NASA Technical Reports Server (NTRS)

1978-01-01

NASA services of interest to writers and to the news media include personal interviews, daily audio reports of major missions, and projects via automated telephone, research assistance from historians or history monitors at technical libraries, the use of a collection of historical photographs, and the free loan of sound films of NASA research and development activities. The names and phones numbers are listed for public affairs contacts at Headquarters and at each of the major centers and their component installations. An overview of the six NASA program offices is included along with a vicinity map of each center and a description of their facilities and management responsibilities.

Safety and efficacy of cardiac rehabilitation for patients with continuous flow left ventricular assist devices.

PubMed

Marko, Christiane; Danzinger, Georg; Käferbäck, Michael; Lackner, Thomas; Müller, Rudolf; Zimpfer, Daniel; Schima, Heinrich; Moscato, Francesco

2015-11-01

Despite the increasing use of left ventricular assist devices (LVADs) in terminal heart failure, cardiac rehabilitation protocols have not yet been documented in larger LVAD patient cohorts. The aim of this study was to investigate safety and efficacy of exercise training during a rehabilitation programme after post-operative discharge of LVAD patients. Rehabilitation data obtained between 2010-2012 from 41 LVAD patients (mean age 54.8 ± 11.6 years; 20% female) were retrospectively analysed. The exercise protocol consisted of strength exercises for lower limbs, bicycle ergometry, walking and gymnastics. The numbers of training sessions, their duration and intensity as well as adverse events were documented. Spiroergometry was performed at least once and twice in a subgroup of 15 patients (at the beginning and end of rehabilitation). Rehabilitation started 48 ± 38 days post LVAD implantation with an average duration of 32 ± 6 days. An increase in exercise capacity was observed. Duration (19 ± 4 vs 14 ± 2 min, p < 0.001) and intensity of bicycle ergometry increased (module number 6.2 ± 2.8 vs 2.0 ± 1.9, p < 0.001) as well as muscular strength all muscle groups trained (e.g. 33.6 ± 15.2 vs 26.6 ± 11.9 kg at the leg press, p = 0.002). Spiroergometry revealed an increase of maximal oxygen consumption (14.5 ± 5.2 vs 11.3 ± 4.1 ml/min/kg, p = 0.007) in the subgroup that underwent two examinations. In the whole population the average increase was lower (12.81 ± 4.35 ml/min/kg). One training-related adverse event (non-sustained ventricular tachycardia) was observed. Exercise training for LVAD patient as part of a multidisciplinary rehabilitation programme is effective and safe. This warrants the broad application of exercise training after LVAD implantation. © The European Society of Cardiology 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Elevated Body Mass Index Is Not a Risk Factor for Adverse Outcomes Following Ventricular Assist Device Implantation.

PubMed

Hullmann, Jonathan E; Mather, Paul J

2018-06-01

Despite ventricular assist devices (VADs) becoming more common in heart failure (HF) treatment, it is still uncertain which patients are more prone to complications. One potential risk factor is increased body mass index (BMI), which is known to increase both all-cause mortality and mortality from ischemic heart disease; however, the role of the BMI in predicting morbidity and mortality following device implantation is unclear. The study population for this single-institution retrospective chart review consisted of 136 patients with HF, who underwent VAD implantation between 2004 and 2015. Patients were divided into 2 groups based on their BMI: a nonobese group (18.5 < BMI < 30.0; n = 82) or an obese group (BMI >30.0; n = 54). These groups were compared at baseline and after implantation for survival, hospital readmission, and adverse events. No significant difference was found in initial hospital length of stay, number or length of readmissions, or readmission diagnosis. At 1 year, rates of ongoing device support, orthotopic heart transplant (OHT), and death were not significantly different between groups ( P = .89, P = .90, and P = .70, respectively). Multivariate analysis did not identify obesity as an independent predictor of mortality ( P = .90); only biventricular assist device implantation was associated with decreased survival (hazard ratio [HR] = 5.90, P = .002). Obesity in itself should not preclude the use of VAD support in patients with HF, as carefully selected obese patients were shown to have similar rates of hospital readmission, 1-year outcomes, and survival following device implantation compared to nonobese patients.

NASA Tech Briefs, Summer 1978

NASA Technical Reports Server (NTRS)

1978-01-01

Topics covered include: NASA TU Services: Technology Utilization services that can assist you in learning about and applying NASA technology; New Product Ideas: A summary of selected innovations of value to manufacturers for the development of new products; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Solar Energy; Materials; Life Sciences; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences.

Quality of Life, Depression, and Anxiety in Ventricular Assist Device Therapy: Longitudinal Outcomes for Patients and Family Caregivers.

PubMed

Bidwell, Julie T; Lyons, Karen S; Mudd, James O; Gelow, Jill M; Chien, Christopher V; Hiatt, Shirin O; Grady, Kathleen L; Lee, Christopher S

Patients who receive ventricular assist device (VAD) therapy typically rely on informal caregivers (family members or friends) to assist them in managing their device. The purpose of this study is to characterize changes in person-oriented outcomes (quality of life [QOL], depression, and anxiety) for VAD patients and their caregivers together from pre-implantation to 3 months post-implantation. This was a formal interim analysis from an ongoing prospective study of VAD patients and caregivers (n = 41 dyads). Data on person-oriented outcomes (QOL: EuroQol 5 Dimensions Visual Analog Scale; depression: Patient Health Questionnaire-8; anxiety: Brief Symptom Inventory) were collected at 3 time points (just prior to implantation and at 1 and 3 months post-implantation). Trajectories of change for patients and caregivers on each measure were estimated using latent growth modeling with parallel processes. Patients' QOL improved significantly over time, whereas caregiver QOL worsened. Depression and anxiety also improved significantly among patients but did not change among caregivers. There was substantial variability in change on all outcomes for both patients and their caregivers. This is the first quantitative study of VAD patient-caregiver dyads in modern devices that describes change in person-oriented outcomes from pre-implantation to post-implantation. This work supports the need for future studies that account for the inherent relationships between patient and caregiver outcomes and examine variability in patient and caregiver responses to VAD therapy.

Mechanical ventilation and thoracic artificial lung assistance during mechanical circulatory support with PUCA pump: in silico study.

PubMed

De Lazzari, Claudio; Genuini, Igino; Quatember, Bernhard; Fedele, Francesco

2014-02-01

Patients assisted with left ventricular assist device (LVAD) may require prolonged mechanical ventilatory assistance secondary to postoperative respiratory failure. The goal of this work is the study of the interdependent effects LVAD like pulsatile catheter (PUCA) pump and mechanical ventilatory support or thoracic artificial lung (TAL), by the hemodynamic point of view, using a numerical simulator of the human cardiovascular system. In the simulator, different circulatory sections are described using lumped parameter models. Lumped parameter models have been designed to describe the hydrodynamic behavior of both PUCA pump and thoracic artificial lung. Ventricular behavior atrial and septum functions were reproduced using variable elastance model. Starting from simulated pathological conditions we studied the effects produced on some hemodynamic variables by simultaneous PUCA pump, thoracic artificial lung or mechanical ventilation assistance. Thoracic artificial lung was applied in parallel or in hybrid mode. The effects of mechanical ventilation have been simulated by changing mean intrathoracic pressure value from -4 mmHg to +5 mmHg. The hemodynamic variables observed during the simulations, in different assisted conditions, were: left and right ventricular end systolic (diastolic) volume, systolic/diastolic aortic pressure, mean pulmonary arterial pressure, left and right mean atrial pressure, mean systemic venous pressure and the total blood flow. Results show that the application of PUCA (without mechanical ventilatory assistance) increases the total blood flow, reduces the left ventricular end systolic volume and increases the diastolic aortic pressure. Parallel TAL assistance increases the right ventricular end diastolic (systolic) volume reduction both when PUCA is switched "ON" and both when PUCA is switched "OFF". By switching "OFF" the PUCA pump, it seems that parallel thoracic artificial lung assistance produces a greater cardiac output (respect to

Design and numeric evaluation of a novel axial-flow left ventricular assist device.

PubMed

Toptop, Koral; Kadipasaoglu, Kamuran A

2013-01-01

Virtual design characteristics and performance of the first Turkish axial-flow left ventricular assist device (LVAD) are presented, with emphasis on rotor geometry. The patented rotor design includes a central flow channel carved inside the main block, which carries permanent magnets. A concentric rotor-stator gap minimizes the distance between respective magnets, improving electromagnetic efficiency and creating a second blood pathway. Dual sets of three helical blades, placed on the shaft and external surface of the rotor block, ensure unidirectionality. Hemodynamic performance was tested with computational fluid dynamics (CFD); and rotor-blade geometry was optimized, to maximize overall efficiency d and minimize backflow and wall shear stresses. For a shaft radius of 4.5 mm, rotor blade height of 2.5 mm, and blade inlet and exit metal angles of 67° and 32°, pump operation at the nominal head-flow combination (5 L/min and 100.4 mm Hg) was achieved at a rotor speed of 10,313 rpm. At the nominal point, backflow as percent of total flow was 7.29 and 29.87% at rotor inlet and exit, respectively; overall hydraulic efficiency reached 21.59%; and maximum area-averaged shroud shear was 520 Pa. Overall efficiency peaked at 24.07% for a pump flow of 6.90 L/min, and averaged at 22.57% within the flow range of 4-8 L/min. We concluded that the design satisfies initial rotor design criteria, and that continued studies with diffuser optimization and transient flow analysis are warranted.

Continuous and Pulsatile Pediatric Ventricular Assist Device Hemodynamics with a Viscoelastic Blood Model

PubMed Central

Good, Bryan C.; Deutsch, Steven; Manning, Keefe B.

2015-01-01

Purpose To investigate the effects of pulsatile and continuous pediatric ventricular assist (PVAD) flow and pediatric blood viscoelasticity on hemodynamics in a pediatric aortic graft model. Methods Hemodynamic parameters of pulsatility, along with velocity and wall shear stress (WSS), are analyzed and compared between Newtonian and viscoelastic blood models at a range of physiological pediatric hematocrits using computational fluid dynamics. Results Both pulsatile and continuous PVAD flow lead to a decrease in pulsatility (surplus hemodynamic energy (SHE), ergs/cm3) compared to healthy aortic flow but with continuous PVAD pulsatility up to 2.4 times lower than pulsatile PVAD pulsatility at each aortic outlet. Significant differences are also seen between the two flow modes in velocity and WSS. The higher velocity jet during systole with pulsatile flow leads to higher WSSs at the anastomotic toe and at the aortic branch bifurcations. The lower velocity but continuous flow jet leads to a much different flow field and higher WSSs into diastole. Under a range of physiological pediatric hematocrit (20-60%), both velocity and WSS can vary significantly with the higher hematocrit blood model generally leading to higher peak WSSs but also lower WSSs in regions of flow separation. Conclusions The large decrease in pulsatility seen from continuous PVAD flow could lead to complications in pediatric vascular development while the high WSSs during peak systole from pulsatile PVAD flow could lead to blood damage. Both flow modes lead to similar regions prone to intimal hyperplasia (IH) resulting from low time-averaged WSS (TAWSS) and high oscillatory shear index (OSI). PMID:26643646

NASA Taxonomy 2.0 Project Overview

NASA Technical Reports Server (NTRS)

Dutra, Jayne; Busch, Joseph

2004-01-01

This viewgraph presentation reviews the project to develop a Taxonomy for NASA. The benefits of this project are: Make it easy for various audiences to find relevant information from NASA programs quickly, specifically (1) Provide easy access for NASA Web resources (2) Information integration for unified queries and management reporting ve search results targeted to user interests the ability to move content through the enterprise to where it is needed most (3) Facilitate Records Management and Retention Requirements. In addition the project will assist NASA in complying with E-Government Act of 2002 and prepare NASA to participate in federal projects.

Novel Use of Thalidomide in Recurrent Gastrointestinal Tract Bleeding in Patients with Left Ventricular Assist Devices: A Case Series.

PubMed

Chan, Laura Lihua; Lim, Choon Pin; Lim, Chong Hee; Tan, Teing Ee; Sim, David; Sivathasan, Cumaraswamy

2017-10-01

Bleeding is an important and common complication of left ventricular assist devices (LVADs). One of the common causes of gastrointestinal bleeding is arteriovenous malformations. However, the source of bleeding is often hard to identify. Thalidomide is efficacious in treatment of gastrointestinal (GI) bleeding in non-LVAD patients. We report our experience of the use of thalidomide in the treatment of GI bleeding in four patients with LVAD. Four patients who had recurrent GI bleeding from May 2009 to December 2014 were started on thalidomide. All of them responded to treatment and had no further gastrointestinal bleeding while on thalidomide. One patient developed constipation, requiring thalidomide to be stopped. Another patient developed symptomatic neuropathy, that resolved with reduction of dosage. Thalidomide appears safe and efficacious in LVAD patients with recurrent gastrointestinal bleeding. Copyright © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

NASA Operational Environment Team (NOET): NASA's key to environmental technology

NASA Technical Reports Server (NTRS)

Cook, Beth

1993-01-01

NASA has stepped forward to face the environmental challenge to eliminate the use of Ozone-Layer Depleting Substances (OLDS) and to reduce our Hazardous Air Pollutants (HAP) by 50 percent in 1995. These requirements have been issued by the Clean Air Act, the Montreal Protocol, and various other legislative acts. A proactive group, the NASA Operational Environment Team or NOET, received its charter in April 1992 and was tasked with providing a network through which replacement activities and development experiences can be shared. This is a NASA-wide team which supports the research and development community by sharing information both in person and via a computerized network, assisting in specification and standard revisions, developing cleaner propulsion systems, and exploring environmentally-compliant alternatives to current processes.

Pathology in patients with ventricular assist devices: a study of 21 autopsies, 24 ventricular apical core biopsies and 24 explanted hearts.

PubMed

Rose, Alan G; Park, Soon J

2005-01-01

Ventricular assist devices (VADs) are used as a bridge to cardiac transplantation or as a permanent or sometimes temporary treatment for end stage heart failure. Our autopsy and surgical pathology experience with VADs prior to August 2002 was reviewed. Noted were patient's age, sex, underlying (UCOD) and proximate causes of death (PCOD), duration of VAD implantation, presence of native or prosthetic valvar disease and organ complications. Myocardium from biopsies and explanted hearts were blindly assessed for coagulative necrosis (CN), contraction bands (CB), myocytolysis (MC), increased eosinophilia (IE), myocyte waviness (MW) and fibrosis (F). Each was graded as either mild (score 1), moderate (score 2) or severe (score 3). Autopsy patients: Twenty-one patients, with mean age 55 years (range 10-73), comprised 10 women and 11 men. UCOD was ischemic disease in 16 patients, dilated cardiomyopathy in 4 and aortic valve disease in 1. The mean duration of VAD implantation was 125.7 days (range 1-1095 days, S.D.=253.6). Five patients had biventricular VADs, and 16 had LVAD only. Acquired aortic valve fusion was noted in three patients. PCOD was VAD related in six, donor heart problem in four, cerebrovascular accident in four, miscellaneous in three, pulmonary hypertension in two and aortic disease in two patients. Morbidity: local liver necrosis in seven, acquired aortic valve disease in four, gut infarction in three, abdominal aortic aneurysm in two and host cell assault against VAD porcine aortic valves in one case. Biopsies and explanted hearts: Twenty-four patients had a mean age of 53 years (range 38-68, S.D.=8.6). VADs were implanted for 177.8 days (range 7-593 days, S.D.=151.1). Comparison of histologic scores of biopsies with explanted hearts showed the following: CN 1.33 (S.D.=1.4)/0.21 (S.D.=0.66; P<.001); CB: 2.1 (S.D.=0.93)/0.83 (S.D.=0.28; NS); MC: 0.88 (S.D.=1.19)/0.13 (S.D.=0.34; P<.01); IE: 1.71 (S.D.=1.27)/0.38 (S.D.=0.65; NS); fibrosis: 1.08 (S.D.=1

Recovery of Serum Cholesterol Predicts Survival After Left Ventricular Assist Device Implantation

PubMed Central

Vest, Amanda R.; Kennel, Peter J.; Maldonado, Dawn; Young, James B.; Mountis, Maria M.; Naka, Yoshifumi; Colombo, Paolo C.; Mancini, Donna M.; Starling, Randall C.; Schulze, P. Christian

2017-01-01

Background Advanced systolic heart failure is associated with myocardial and systemic metabolic abnormalities, including low levels of total cholesterol and low-density lipoprotein. Low cholesterol and low-density lipoprotein have been associated with greater mortality in heart failure. Implantation of a left ventricular assist device (LVAD) reverses some of the metabolic derangements of advanced heart failure. Methods and Results A cohort was retrospectively assembled from 2 high-volume implantation centers, totaling 295 continuous-flow LVAD recipients with ≥2 cholesterol values available. The cohort was predominantly bridge-to-transplantation (67%), with median age of 59 years and 49% ischemic heart failure cause. Total cholesterol, low-density lipoprotein, high-density lipoprotein, and triglyceride levels all significantly increased after LVAD implantation (median values from implantation to 3 months post implantation 125–150 mg/dL, 67–85 mg/dL, 32–42 mg/dL, and 97–126 mg/dL, respectively). On Cox proportional hazards modeling, patients achieving recovery of total cholesterol levels, defined as a median or greater change from pre implantation to 3 months post-LVAD implantation, had significantly better unadjusted survival (hazard ratio, 0.445; 95% confidence interval, 0.212–0.932) and adjusted survival (hazard ratio, 0.241; 95% confidence interval, 0.092–0.628) than those without cholesterol recovery after LVAD implantation. The continuous variable of total cholesterol at 3 months post implantation and the cholesterol increase from pre implantation to 3 months were also both significantly associated with survival during LVAD support. Conclusions Initiation of continuous-flow LVAD support was associated with significant recovery of all 4 lipid variables. Patients with a greater increase in total cholesterol by 3 months post implantation had superior survival during LVAD support. PMID:27623768

Steroid therapy attenuates acute phase reactant response among children on ventricular assist device support.

PubMed

Byrnes, Jonathan W; Bhutta, Adnan T; Rettiganti, Mallikarjuna Rao; Gomez, Alberto; Garcia, Xiomara; Dyamenahalli, Umesh; Johnson, Charles; Jaquiss, Robert D B; Imamura, Michiaki; Prodhan, Parthak

2015-04-01

Hyperfibrinogenemia, which can create a procoagulant milieu, is frequently observed in patients supported with the Berlin EXCOR (Berlin Heart GmbH, Berlin, Germany) ventricular assist device (VAD). We began initiating corticosteroids in patients with systemic inflammatory response syndrome (SIRS) episodes to mitigate hyperfibrinogenemia. We set forth to describe the impact of corticosteroids on the hyperfibrinogenemic state in our institutional experience. Retrospective data was collected on 44 consecutive patients implanted with the Berlin EXCOR VAD from April 15, 2005 through May 6, 2013. Pertinent information was abstracted from the electronic medical record. The reduction of C-reactive protein (CRP) and fibrinogen levels among days from corticosteroid treatment were described. Infections and insulin use were reported based on whether patients received steroids and if steroids were given for SIRS. Over the initial 44 Berlin EXCOR VAD implantations, 14 patients were treated with 21 courses of corticosteroids for SIRS episodes as identified by clinical features and rise in CRP. Treatment with corticosteroids reduced fibrinogen levels by day 2 to a statistically significant degree (p = 0.008). No difference in hyperglycemia or infections occurred among patients receiving corticosteroids for SIRS. Treatment with corticosteroids can potentially mitigate the SIRS response among children supported on the Berlin EXCOR VAD. In patients who received corticosteroids to mitigate inflammation, there was no increase in infections or hyperglycemia requiring insulin administration compared with patients who did not receive steroids. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Systolic ventricular filling.

PubMed

Torrent-Guasp, Francisco; Kocica, Mladen J; Corno, Antonio; Komeda, Masashi; Cox, James; Flotats, A; Ballester-Rodes, Manel; Carreras-Costa, Francesc

2004-03-01

The evidence of the ventricular myocardial band (VMB) has revealed unavoidable coherence and mutual coupling of form and function in the ventricular myocardium, making it possible to understand the principles governing electrical, mechanical and energetical events within the human heart. From the earliest Erasistratus' observations, principal mechanisms responsible for the ventricular filling have still remained obscured. Contemporary experimental and clinical investigations unequivocally support the attitude that only powerful suction force, developed by the normal ventricles, would be able to produce an efficient filling of the ventricular cavities. The true origin and the precise time frame for generating such force are still controversial. Elastic recoil and muscular contraction were the most commonly mentioned, but yet, still not clearly explained mechanisms involved in the ventricular suction. Classical concepts about timing of successive mechanical events during the cardiac cycle, also do not offer understandable insight into the mechanism of the ventricular filling. The net result is the current state of insufficient knowledge of systolic and particularly diastolic function of normal and diseased heart. Here we summarize experimental evidence and theoretical backgrounds, which could be useful in understanding the phenomenon of the ventricular filling. Anatomy of the VMB, and recent proofs for its segmental electrical and mechanical activation, undoubtedly indicates that ventricular filling is the consequence of an active muscular contraction. Contraction of the ascendent segment of the VMB, with simultaneous shortening and rectifying of its fibers, produces the paradoxical increase of the ventricular volume and lengthening of its long axis. Specific spatial arrangement of the ascendent segment fibers, their interaction with adjacent descendent segment fibers, elastic elements and intra-cavitary blood volume (hemoskeleton), explain the physical principles

Development of an Outreach Program for NASA: "NASA Ambassadors"

NASA Technical Reports Server (NTRS)

Lebo, George

1998-01-01

The NASA Ambassadors Program is designed to present the excitement and importance of NASA's programs to its customers, the general public. Those customers, which are identified in the "Science Communications Strategy" developed by the Space Sciences Laboratory at the MSFC, are divided into three categories: (1) Not interested and not knowledgeable; (2) Interested but not knowledgeable; and (3) Science attentive. In it they recognize that it makes the most sense to attempt to communicate with those described in the last two categories. However, their plan suggests that the media and the educational institutions are the only means of outreach. The NASA Ambassadors Program allows NASA to reach its target audience directly. Steps to be taken in order for the program to commence: (1) MSFC chooses to support the NASA Ambassadors Program - decision point; (2) Designate an "Office In Charge". (3) Assign the "Operation" phase to in-house MSFC personnel or to a contractor - decision point; (4) Name a point of contact; (5) Identify partners in the program and enlist their assistance; (6) Process an unsolicited proposal from an outside source to accomplish those tasks which MSFC chooses to out-source.

Thoracic Epidural Anesthesia Reduces Right Ventricular Systolic Function With Maintained Ventricular-Pulmonary Coupling.

PubMed

Wink, Jeroen; de Wilde, Rob B P; Wouters, Patrick F; van Dorp, Eveline L A; Veering, Bernadette Th; Versteegh, Michel I M; Aarts, Leon P H J; Steendijk, Paul

2016-10-18

Blockade of cardiac sympathetic fibers by thoracic epidural anesthesia may affect right ventricular function and interfere with the coupling between right ventricular function and right ventricular afterload. Our main objectives were to study the effects of thoracic epidural anesthesia on right ventricular function and ventricular-pulmonary coupling. In 10 patients scheduled for lung resection, right ventricular function and its response to increased afterload, induced by temporary, unilateral clamping of the pulmonary artery, was tested before and after induction of thoracic epidural anesthesia using combined pressure-conductance catheters. Thoracic epidural anesthesia resulted in a significant decrease in right ventricular contractility (ΔESV 25 : +25.5 mL, P=0.0003; ΔEes: -0.025 mm Hg/mL, P=0.04). Stroke work, dP/dt MAX , and ejection fraction showed a similar decrease in systolic function (all P<0.05). A concomitant decrease in effective arterial elastance (ΔEa: -0.094 mm Hg/mL, P=0.004) yielded unchanged ventricular-pulmonary coupling. Cardiac output, systemic vascular resistance, and mean arterial blood pressure were unchanged. Clamping of the pulmonary artery significantly increased afterload (ΔEa: +0.226 mm Hg/mL, P<0.001). In response, right ventricular contractility increased (ΔESV 25 : -26.6 mL, P=0.0002; ΔEes: +0.034 mm Hg/mL, P=0.008), but ventricular-pulmonary coupling decreased (Δ(Ees/Ea) = -0.153, P<0.0001). None of the measured indices showed significant interactive effects, indicating that the effects of increased afterload were the same before and after thoracic epidural anesthesia. Thoracic epidural anesthesia impairs right ventricular contractility but does not inhibit the native positive inotropic response of the right ventricle to increased afterload. Right ventricular-pulmonary arterial coupling was decreased with increased afterload but not affected by the induction of thoracic epidural anesthesia. URL: http

Flow Visualization of Three-Dimensionality Inside the 12 cc Penn State Pulsatile Pediatric Ventricular Assist Device

PubMed Central

Roszelle, Breigh N.; Deutsch, Steven; Manning, Keefe B.

2010-01-01

In order to aid the ongoing concern of limited organ availability for pediatric heart transplants, Penn State has continued development of a pulsatile Pediatric Ventricular Assist Device (PVAD). Initial studies of the PVAD observed an increase in thrombus formation due to differences in flow field physics when compared to adult sized devices, which included a higher degree of three-dimensionality. This unique flow field brings into question the use of 2D planar particle image velocimetry (PIV) as a flow visualization technique, however the small size and high curvature of the PVAD make other tools such as stereoscopic PIV impractical. In order to test the reliability of the 2D results, we perform a pseudo-3D PIV study using planes both parallel and normal to the diaphragm employing a mock circulatory loop containing a viscoelastic fluid that mimics 40% hematocrit blood. We find that while the third component of velocity is extremely helpful to a physical understanding of the flow, particularly of the diastolic jet and the development of a desired rotational pattern, the flow data taken parallel to the diaphragm is sufficient to describe the wall shear rates, a critical aspect to the study of thrombosis and design of such pumps. PMID:19936926

Effects of continuous and pulsatile flows generated by ventricular assist devices on renal function and pathology.

PubMed

Miyamoto, Takuma; Karimov, Jamshid H; Fukamachi, Kiyotaka

2018-03-01

Continuous-flow (CF) left ventricular assist devices (LVADs) are widely used to treat end-stage heart failure. Despite substantial improvement in clinical results, numerous complications remain associated with this technology. Worsening renal function is one, associated with morbidity and mortality in patients supported by CF LVADs. The effects of CF LVAD support on renal function have been investigated since the mid-1990s by many research groups. Area covered: We review the current status of LVAD therapy, experimental results regarding the effects of types of flow generated by LVADs on renal function and pathology, changes in renal function after LVAD implant, the influence of renal function on outcomes, and risk factors for renal dysfunction post implant. This information was obtained through online databases and direct extraction of single studies. Expert commentary: Immediately after CF LVAD implantation, renal function improves temporarily as patients recover from the kidneys' previously low perfusion and congestive state. However, many studies have shown that this initially recovered renal function gradually declines during long-term CF LVAD support. Although it is known that CF LVAD support adversely affects renal function over the long term, just how it does has not yet been clearly defined in terms of clinical symptoms or signs.

48 CFR 1837.203 - Policy. (NASA supplements paragraph (c))

Code of Federal Regulations, 2013 CFR

2013-10-01

... 48 Federal Acquisition Regulations System 6 2013-10-01 2013-10-01 false Policy. (NASA supplements... Services 1837.203 Policy. (NASA supplements paragraph (c)) (c) Advisory and assistance services of... 3300.1, Appointment of Personnel To/From NASA, Chapter 4, Employment of Experts and Consultants). [62...

48 CFR 1837.203 - Policy. (NASA supplements paragraph (c))

Code of Federal Regulations, 2011 CFR

2011-10-01

... 48 Federal Acquisition Regulations System 6 2011-10-01 2011-10-01 false Policy. (NASA supplements... Services 1837.203 Policy. (NASA supplements paragraph (c)) (c) Advisory and assistance services of... 3300.1, Appointment of Personnel To/From NASA, Chapter 4, Employment of Experts and Consultants). [62...

48 CFR 1837.203 - Policy. (NASA supplements paragraph (c))

Code of Federal Regulations, 2012 CFR

2012-10-01

... 48 Federal Acquisition Regulations System 6 2012-10-01 2012-10-01 false Policy. (NASA supplements... Services 1837.203 Policy. (NASA supplements paragraph (c)) (c) Advisory and assistance services of... 3300.1, Appointment of Personnel To/From NASA, Chapter 4, Employment of Experts and Consultants). [62...

48 CFR 1837.203 - Policy. (NASA supplements paragraph (c))

Code of Federal Regulations, 2014 CFR

2014-10-01

... 48 Federal Acquisition Regulations System 6 2014-10-01 2014-10-01 false Policy. (NASA supplements... Services 1837.203 Policy. (NASA supplements paragraph (c)) (c) Advisory and assistance services of... 3300.1, Appointment of Personnel To/From NASA, Chapter 4, Employment of Experts and Consultants). [62...

48 CFR 1837.203 - Policy. (NASA supplements paragraph (c))

Code of Federal Regulations, 2010 CFR

2010-10-01

... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true Policy. (NASA supplements... Services 1837.203 Policy. (NASA supplements paragraph (c)) (c) Advisory and assistance services of... 3300.1, Appointment of Personnel To/From NASA, Chapter 4, Employment of Experts and Consultants). [62...

Design and Development of a Miniaturized Percutaneously Deployable Wireless Left Ventricular Assist Device: Early Prototypes and Feasibility Testing.

PubMed

Letzen, Brian; Park, Jiheum; Tuzun, Zeynep; Bonde, Pramod

The current left ventricular assist devices (LVADs) are limited by a highly invasive implantation procedure in a severely unstable group of advanced heart failure patients. Additionally, the current transcutaneous power drive line acts as a nidus for infection resulting in significant morbidity and mortality. In an effort to decrease this invasiveness and eliminate drive line complications, we have conceived a wireless miniaturized percutaneous LVAD, capable of being delivered endovascularly with a tether-free operation. The system obviates the need for a transcutaneous fluid purge line required in existing temporary devices by utilizing an incorporated magnetically coupled impeller for a complete seal. The objective of this article was to demonstrate early development and proof-of-concept feasibility testing to serve as the groundwork for future formalized device development. Five early prototypes were designed and constructed to iteratively minimize the pump size and improve fluid dynamic performance. Various magnetic coupling configurations were tested. Using SolidWorks and ANSYS software for modeling and simulation, several geometric parameters were varied. HQ curves were constructed from preliminary in vitro testing to characterize the pump performance. Bench top tests showed no-slip magnetic coupling of the impeller to the driveshaft up to the current limit of the motor. The pump power requirements were tested in vitro and were within the appropriate range for powering via a wireless energy transfer system. Our results demonstrate the proof-of-concept feasibility of a novel endovascular cardiac assist device with the potential to eventually offer patients an untethered, minimally invasive support.

Investigation of membranous ventricular septal defect complicated with tricuspid regurgitation in ventricular septal defect occlusion

PubMed Central

LIU, SHU-PING; LI, LI; YAO, KE-CHUN; WANG, NA; WANG, JIAN-CHANG

2013-01-01

This study aimed to explore the mechanism of membranous ventricular septal defect complicated with tricuspid regurgitation and the significance of ventricular septal defect occlusion by echocardiography. A total of 43 patients with membranous ventricular septal defect complicated with tricuspid regurgitation were observed by echocardiography and the changes in length, area and volume of tricuspid regurgitation prior to and following ventricular septal defect occlusion were measured. There were four different mechanisms of membranous ventricular septal defect complicated with tricuspid regurgitation. The various indices of tricuspid regurgitation volume were significantly reduced following occlusion. Ventricular septal defect occlusion significantly reduces tricuspid regurgitation volume complicated with membranous ventricular septal defect and echocardiography is an ideal method to detect these changes. PMID:23404058

NASA Initiatives with Historically Black Colleges & Universities.

ERIC Educational Resources Information Center

National Aeronautics and Space Administration, Washington, DC.

This publication outlines the involvement of the National Aeronautics and Space Administration (NASA) with Historically Black Colleges and Universities (HBCU) programs in aeronautics and space research. NASA aims to assist HBCUs in science, engineering, and technology programs and also to encourage greater participation of minorities in its…

Development of a compact wearable pneumatic drive unit for a ventricular assist device.

PubMed

Homma, Akihiko; Taenaka, Yoshiyuki; Tatsumi, Eisuke; Akagawa, Eiki; Lee, Hwansung; Nishinaka, Tomohiro; Takewa, Yoshiaki; Mizuno, Toshihide; Tsukiya, Tomonori; Kakuta, Yukihide; Katagiri, Nobumasa; Shimosaki, Isao; Hamada, Shigeru; Mukaibayashi, Hiroshi; Iwaoka, Wataru

2008-01-01

The purpose of this study was to develop a compact wearable pneumatic drive unit for a ventricular assist device (VAD). This newly developed drive unit, 20 x 8.5 x 20 cm in size and weighing approximately 1.8 kg, consists of a brushless DC motor, noncircular gears, a crankshaft, a cylinder-piston, and air pressure regulation valves. The driving air pressure is generated by the reciprocating motion of the piston and is controlled by the air pressure regulation valves. The systolic ratio is determined by the noncircular gears, and so is fixed for a given configuration. As a result of an overflow-type mock circulation test, a drive unit with a 44% systolic ratio connected to a Toyobo VAD blood pump with a 70-ml stroke volume achieved a pump output of more than 7 l/min at 100 bpm against a 120 mmHg afterload. Long-term animal tests were also performed using drive units with systolic ratios of 45% and 53% in two Holstein calves weighing 62 kg and 74 kg; the tests were terminated on days 30 and 39, respectively, without any malfunction. The mean aortic pressure, bypass flow, and power consumption for the first calf were maintained at 90 x 13 mmHg, 3.9 x 0.9 l/min, and 12 x 1 W, and those for the second calf were maintained at 88 x 13 mmHg, 5.0 x 0.5 l/min, and 16 x 2 W, respectively. These results indicate that the newly developed drive unit may be used as a wearable pneumatic drive unit for the Toyobo VAD blood pump.

The perioperative management of patients with left ventricular assist devices undergoing noncardiac surgery.

PubMed

Barbara, David W; Wetzel, David R; Pulido, Juan N; Pershing, Bryan S; Park, Soon J; Stulak, John M; Zietlow, Scott P; Morris, David S; Boilson, Barry A; Mauermann, William J

2013-07-01

To describe the perioperative management of patients with left ventricular assist devices (LVADs) who require general anesthesia while undergoing noncardiac surgery (NCS) at a single, large tertiary referral center. Electronic medical records from September 2, 2005, through May 31, 2012, were retrospectively reviewed to evaluate the perioperative management and outcomes in LVAD patients undergoing NCS. Patients were included only if they required a general anesthetic and had previously been discharged from the hospital after initial LVAD implantation. Thirty-three patients with LVADs underwent general anesthesia for 67 noncardiac operations. The mean ± SD time from LVAD implantation to NCS was 317 ± 349 days. All but 1 patient had axial flow LVADs. Anticoagulation or antiplatelet agents were present within 7 days before NCS in 49 procedures (73%) and reversed in 32 of 49 (65%). No perioperative thrombotic complications related to anticoagulation or antiplatelet reversal were noted. Red blood cell, fresh frozen plasma, and platelet transfusions were administered during 10, 6, and 4 operations, respectively. The only intraoperative complication was surgical bleeding. Postoperative complications were present in 12 patients after NCS and were mainly composed of bleeding. Three patients died within 30 days of NCS, with the causes of death not attributed to NCS. Patients with LVAD safely underwent NCS in a multidisciplinary setting that included preoperative optimization by cardiologists familiar with LVADs when feasible. Anticoagulation or antiplatelet agents were present preoperatively in most patients with LVADs and were safely reversed when necessary for NCS. The relatively high occurrence of postoperative bleeding is consistent with previous series. Copyright © 2013 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.

Catheter ablation for premature ventricular contractions and ventricular tachycardia in patients with heart failure.

PubMed

Kumar, Saurabh; Stevenson, William G; John, Roy M

2014-09-01

Ventricular arrhythmias (VA) are a significant contributor to morbidity and mortality in patients with heart failure (HF). Implantable cardioverter defibrillators are effective in reducing mortality, but do not prevent arrhythmia recurrence. There is increasing recognition that frequent premature ventricular contractions or repetitive ventricular tachycardia may also lead to new onset ventricular dysfunction or deterioration of ventricular function in patients with pre-existing HF. Suppression of the arrhythmia may lead to recovery of ventricular function. Catheter ablation has emerged as a safe and effective treatment option for reducing arrhythmia recurrence and for suppression of PVCs but its efficacy is governed by the nature of the arrhythmias, the underlying HF substrate and the accessibility of the arrhythmia substrates to ablation.

Exertional Angina Due To Fused Aortic Bioprosthesis During Left Ventricular Assist Device Support: Two Cases and Review of the Literature.

PubMed

Bonios, Michael J; Selzman, Craig H; Gilbert, Edward M; McKellar, Stephen H; Koliopoulou, Antigoni; Strege, Jennifer L; Nativi, Jose N; Fang, James C; Stehlik, Josef; Drakos, Stavros G

We present the case of two patients with idiopathic dilated cardiomyopathy and moderate aortic valve regurgitation that were treated with a bioprosthetic valve at the time of the left ventricular assist device (LVAD) implantation. A few months later, patients revealed partial recovery in the left ventricle systolic function. Both patients, during the LVAD turndown protocol, reported the onset of chest pain. The transthoracic echocardiography revealed the presence of a new transaortic pressure gradient. We confirmed the presence of a fused bioprosthetic valve by further performing a transesophageal echocardiogram and a left and right heart catheterization. Replacement of aortic valve at the time of an LVAD implantation constitutes a challenging case. Although a mechanical valve is contraindicated due to the increased thromboembolic risk, selecting a bioprosthetic valve increases the risk of valve leaflets fusion. The consequences of this phenomenon should be acknowledged in LVAD patients undergoing aortic valve replacement with a bioprosthetic, especially under the view of LVAD explantation for those revealing myocardial recovery under mechanical unloading.

14 CFR 1212.705 - Assistant Administrator for Procurement.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true Assistant Administrator for Procurement. 1212.705 Section 1212.705 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PRIVACY ACT-NASA REGULATIONS NASA Authority and Responsibilities § 1212.705 Assistant Administrator for...

14 CFR 1212.705 - Assistant Administrator for Procurement.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Assistant Administrator for Procurement. 1212.705 Section 1212.705 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PRIVACY ACT-NASA REGULATIONS NASA Authority and Responsibilities § 1212.705 Assistant Administrator for...

Left ventricular rotation and torsion in patients with perimembranous ventricular septal defect.

PubMed

Zhuang, Yan; Yong, Yong-hong; Yao, Jing; Ji, Ling; Xu, Di

2014-03-01

Assessment of left ventricular (LV) rotation has become an important approach for quantifying LV function. In this study, we sought to analyze LV rotation and twist using speckle tracking imaging (STI) in adult patients with isolated ventricular septal defects. Using STI, the peak rotation and time to peak rotation of 6 segments in basal and apical short-axis were measured, respectively, in 32 patients with ventricular septal defect and 30 healthy subjects as controls. The global rotation of the 6 segments in basal and apical and LV twist versus time profile were drawn, the peak rotation and twist of LV were calculated. All the time to peak rotation/twist were expressed as a percentage of end-systole (end-systole = 100%). Left ventricular ejection fraction was measured by biplane Simpson method. In patients group, the peak rotation of posterior, inferior, and postsept wall in basal was higher(P ≤ 0.05) and LV twist was also higher (P ≤ 0.05) than healthy controls. There were no significant differences between 2 groups in the peak rotation of the other 9 segments and left ventricular ejection fraction. Different from the control group, the time to peak rotation of the 6 segments in basal were delayed and the global rotation of the base was delayed (P ≤ 0.05) in ventricular septal defect group. Left ventricular volume overload due to ventricular septal defect has significant effect on LV rotation and twist, and LV rotation and twist may be a new index predicting LV systolic function. © 2013, Wiley Periodicals, Inc.

Adverse ventricular-ventricular interactions in right ventricular pressure load: Insights from pediatric pulmonary hypertension versus pulmonary stenosis.

PubMed

Driessen, Mieke M P; Hui, Wei; Bijnens, Bart H; Dragulescu, Andreea; Mertens, Luc; Meijboom, Folkert J; Friedberg, Mark K

2016-06-01

Right ventricular (RV) pressure overload has a vastly different clinical course in children with idiopathic pulmonary arterial hypertension (iPAH) than in children with pulmonary stenosis (PS). While RV function is well recognized as a key prognostic factor in iPAH, adverse ventricular-ventricular interactions and LV dysfunction are less well characterized and the pathophysiology is incompletely understood. We compared ventricular-ventricular interactions as hypothesized drivers of biventricular dysfunction in pediatric iPAH versus PS Eighteen iPAH, 16 PS patients and 18 age- and size-matched controls were retrospectively studied. Cardiac cycle events were measured by M-mode and Doppler echocardiography. Measurements were compared between groups using ANOVA with post hoc Dunnet's or ANCOVA including RV systolic pressure (RVSP; iPAH 96.8 ± 25.4 mmHg vs. PS 75.4 ± 18.9 mmHg; P = 0.011) as a covariate. RV-free wall thickening was prolonged in iPAH versus PS, extending beyond pulmonary valve closure (638 ± 76 msec vs. 562 ± 76 msec vs. 473 ± 59 msec controls). LV and RV isovolumetric relaxation were prolonged in iPAH (P < 0.001; LV 102.8 ± 24.1 msec vs. 63.1 ± 13.7 msec; RV 95 [61-165] vs. 28 [0-43]), associated with adverse septal kinetics; characterized by rightward displacement in early systole and leftward displacement in late RV systole (i.e., early LV diastole). Early LV diastolic filling was decreased in iPAH (73 ± 15.9 vs. PS 87.4 ± 14.4 vs. controls 95.8 ± 12.5 cm/sec; P = 0.004). Prolonged RVFW thickening, prolonged RVFW isovolumetric times, and profound septal dyskinesia are associated with interventricular mechanical discoordination and decreased early LV filling in pediatric iPAH much more than PS These adverse mechanics affect systolic and diastolic biventricular efficiency in iPAH and may form the basis for worse clinical outcomes. We used clinically derived data to study the pathophysiology of ventricular-ventricular

Octreotide for left ventricular assist device-related gastrointestinal hemorrhage: can we stop the bleeding?

PubMed

Rennyson, Stephen L; Shah, Keyur B; Tang, Daniel G; Kasirajan, Vigneshwar; Pedram, Sammy; Cahoon, William; Malhotra, Rajiv

2013-01-01

Left ventricular support devices (LVADs) are associated with a propensity toward gastrointestinal bleeding. A postulated mechanism is related to gastrointestinal arteriovenous malformations secondary to nonpulsatile flow. We describe a case of LVAD-related, gastrointestinal bleeding successfully treated with a combination of subcutaneous and intramuscular depot formulations of octreotide.

Optimal Timing of Heart Transplant After HeartMate II Left Ventricular Assist Device Implantation.

PubMed

Steffen, Robert J; Blackstone, Eugene H; Smedira, Nicholas G; Soltesz, Edward G; Hoercher, Katherine J; Thuita, Lucy; Starling, Randall C; Mountis, Maria; Moazami, Nader

2017-11-01

Optimal timing of heart transplantation in patients supported with second-generation left ventricular assist devices (LVADs) is unknown. Despite this, patients with LVADs continue to receive priority on the heart transplant waiting list. Our objective was to determine the optimal timing of transplantation for patients bridged with continuous-flow LVADs. A total of 301 HeartMate II LVADs (Thoratec Corp, Pleasanton, CA) were implanted in 285 patients from October 2004 to June 2013, and 86 patients underwent transplantation through the end of follow-up. Optimal transplantation timing was the product of surviving on LVAD support and surviving transplant. Three-year survival after both HeartMate II implantation and heart transplantation was unchanged when transplantation occurred within 9 months of implantation. Survival decreased as the duration of support exceeded this. Preoperative risk factors for death on HeartMate II support were prior valve operation, prior coronary artery bypass grafting, low albumin, low glomerular filtration rate, higher mean arterial pressure, hypertension, and earlier date of implant. Survival for patients without these risk factors was lowest when transplant was performed within 3 months but was relatively constant with increased duration of support. Longer duration of support was associated with poorer survival for patients with many of these risk factors. Device reimplantation, intracranial hemorrhage, and postimplant dialysis during HeartMate II support were associated with decreased survival. Survival of patients supported by the HeartMate II is affected by preoperative comorbidities and postoperative complications. Transplantation before complications is imperative in optimizing survival. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Software Safety Progress in NASA

NASA Technical Reports Server (NTRS)

Radley, Charles F.

1995-01-01

NASA has developed guidelines for development and analysis of safety-critical software. These guidelines have been documented in a Guidebook for Safety Critical Software Development and Analysis. The guidelines represent a practical 'how to' approach, to assist software developers and safety analysts in cost effective methods for software safety. They provide guidance in the implementation of the recent NASA Software Safety Standard NSS-1740.13 which was released as 'Interim' version in June 1994, scheduled for formal adoption late 1995. This paper is a survey of the methods in general use, resulting in the NASA guidelines for safety critical software development and analysis.

NASA Software Safety Standard

NASA Technical Reports Server (NTRS)

Rosenberg, Linda

1997-01-01

If software is a critical element in a safety critical system, it is imperative to implement a systematic approach to software safety as an integral part of the overall system safety programs. The NASA-STD-8719.13A, "NASA Software Safety Standard", describes the activities necessary to ensure that safety is designed into software that is acquired or developed by NASA, and that safety is maintained throughout the software life cycle. A PDF version, is available on the WWW from Lewis. A Guidebook that will assist in the implementation of the requirements in the Safety Standard is under development at the Lewis Research Center (LeRC). After completion, it will also be available on the WWW from Lewis.

Non-Dimensional Formulation of Ventricular Work-Load Severity Under Concomitant Heart Valve Disease

NASA Astrophysics Data System (ADS)

Dong, Melody; Simon-Walker, Rachael; Dasi, Lakshmi

2012-11-01

Current guidelines on assessing the severity of heart valve disease rely on dimensional disease specific measures and are thus unable to capture severity under a concomitant heart valve disease scenario. Experiments were conducted to measure ventricular work-load in an in-house in-vitro left heart simulator. In-house tri-leaflet heart valves were built and parameterized to model concomitant heart valve disease. Measured ventricular power varied non-linearly with cardiac output and mean aortic pressure. Significant data collapse could be achieved by the non-dimensionalization of ventricular power with cardiac output, fluid density, and a length scale. The dimensionless power, Circulation Energy Dissipation Index (CEDI), indicates that concomitant conditions require a significant increase in the amount of work needed to sustain cardiac function. It predicts severity without the need to quantify individual disease severities. This indicates the need for new fluid-dynamics similitude based clinical guidelines to assist patients with multiple heart valve diseases. Funded by the American Heart Association.

Significance of postshunt ventricular asymmetries.

PubMed

Linder, M; Diehl, J T; Sklar, F H

1981-08-01

Ventricular asymmetries after shunt surgery were studied. Right and left ventricular areas from pre-and postoperative computerized tomography scans were measured with a computer digitizing technique, and the respective areas were expressed as a ratio. Measurements were made from the scans of 15 hydrocephalic children selected at random. Ages at surgery ranged from 1 to 101 weeks. The results indicate a significantly greater decrease in ventricular size on the side of the ventricular shunt catheter. Multiple regression analysis showed no relationship between the magnitude of change in ventricular size and either the patients' age orn the time intervals between surgery and follow-up scans. Possible mechanisms for these postshunt ventricular asymmetries are discussed.

NASA Helps Build Colorado Economy

NASA Image and Video Library

2010-12-13

NASA Deputy Administrator Lori Garver delivers remarks at the Colorado State Capitol in Denver on Monday, Dec. 13, 2010, prior to signing an agreement that creates a Technology Acceleration Program and Regional Innovation Cluster for Aerospace and Clean Energy. A manufacturing park focused on rapid new product development and production will be developed to assist growing Colorado businesses while promoting the commercialization of technology developed for the space program. Photo Credit: (NASA/Bill Ingalls)

NASA/USRA University advanced design program

NASA Technical Reports Server (NTRS)

Lembeck, Michael F.; Prussing, John

1989-01-01

The participation of the University of Illinois at Urbana-Champaign in the NASA/USRA University Advanced Design Program for the 1988 to 1989 academic year is reviewed. The University's design project was the Logistics Resupply and Emergency Crew Return System for Space Station Freedom. Sixty-one students divided into eight groups, participated in the spring 1989 semester. A presentation prepared by three students and a graduate teaching assistant for the program's summer conference summarized the project results. Teamed with the NASA Marshall Space Flight Center (MSFC), the University received support in the form of remote telecon lectures, reference material, and previously acquired applications software. In addition, a graduate teaching assistant was awarded a summer 1989 internship at MSFC.

Non-Invasive Assessment of Susceptibility to Ventricular Arrhythmias During Simulated Microgravity

NASA Technical Reports Server (NTRS)

Cohen, Richard J.

1999-01-01

The Cardiovascular Alterations Team is currently conducting studies to determine what alterations in hemodynamic regulation result from sixteen days of simulated microgravity exposure in normal human subjects. In this project we make additional measurements on these same study subjects in order to determine whether there is an increase in susceptibility to ventricular arrhythmias resulting from simulated microgravity exposure. Numerous anecdotal and documented reports from the past 30 years suggest that the incidence of ventricular arrhythmias among astronauts is increased during space flight. For example, documented runs of ventricular tachycardia have been recorded from crew members of Skylab and Mir, there was much attention given by the lay press to Mir Commander Vasily Tslbliyev's complaints of heart rhythm irregularities in July of 1997, and cardiovascular mechanisms may have been causal in the recent death of an experimental primate shortly after return from space. In 1986, a Mir cosmonaut, Alexander Laveikin, was brought home and replaced with an alternate cosmonaut as a result of cardiac dysrhythmias that began during extravehicular activity. Furthermore, at a joint NASA/NSBRI workshop held in January 1998, cardiac arrhythmias were identified as the highest priority cardiovascular risk to a human Mars mission. Despite the evidence for the risk of a potentially lethal arrhythmia resulting from microgravity exposure, the effects of space flight and the associated physiologic stresses on cardiac conduction processes are not known, and an increase in cardiac susceptibility to arrhythmias has never been quantified. In this project, we are determining whether simulated space flight increases the risk of developing life-threatening heart rhythm disturbances such as sustained ventricular tachycardia (defined as ventricular tachycardia lasting at least 30 seconds or resulting in hemodynamic collapse) and ventricular fibrillation. We are obtaining measures of

Ventricular assist devices as bridge to heart transplantation: impact on post-transplant infections.

PubMed

Héquet, Delphine; Kralidis, Georg; Carrel, Thierry; Cusini, Alexia; Garzoni, Christian; Hullin, Roger; Meylan, Pascal R; Mohacsi, Paul; Mueller, Nicolas J; Ruschitzka, Frank; Tozzi, Piergiorgio; van Delden, Christian; Weisser, Maja; Wilhelm, Markus J; Pascual, Manuel; Manuel, Oriol

2016-07-08

Ventricular assist devices (VAD) are valuable options for patients with heart failure awaiting cardiac transplantation. We assessed the impact of pre-transplant VAD implantation on the incidence of post-transplant infections in a nationwide cohort of heart transplant recipients. Heart transplant recipients included in the Swiss Transplant Cohort Study between May 2008 and December 2012 were analyzed. Cumulative incidence curves were used to calculate the incidence of bacterial or Candida infections (primary endpoint) and of other infections (secondary endpoint) after transplant. Cox regression models treating death as a competing risk were used to identify risk factors for the development of infection after transplant. Overall, 119 patients were included in the study, 35 with a VAD and 84 without VAD. Cumulative incidences of post-transplant bacterial or Candida infections were 37.7 % in VAD patients and 40.4 % in non-VAD patients. In multivariate analysis, the use of cotrimoxazole prophylaxis was the only variable associated with bacterial/Candida infections after transplant (HR 0.29 [95 % CI 0.15-0.57], p < 0.001), but presence of a VAD was not (HR 0.94, [95 % CI 0.38-2.32], p = 0.89, for continuous-flow devices, and HR 0.45 [0.15 - 1.34], p = 0.15, for other devices). Risk for post-transplant viral and all fungal infections was not increased in patients with VAD. One-year survival was 82.9 % (29/35) in the VAD group and 82.1 % (69/84) in the non-VAD group. All 6 patients in the VAD group that died after transplant had a history of pre-transplant VAD infection. In this nationwide cohort of heart transplant recipients, the presence of VAD at the time of transplant had no influence on the development of post-transplant infections.

Frailty and outcomes after implantation of left ventricular assist device as destination therapy.

PubMed

Dunlay, Shannon M; Park, Soon J; Joyce, Lyle D; Daly, Richard C; Stulak, John M; McNallan, Sheila M; Roger, Véronique L; Kushwaha, Sudhir S

2014-04-01

Frailty is recognized as a major prognostic indicator in heart failure. There has been interest in understanding whether pre-operative frailty is associated with worse outcomes after implantation of a left ventricular assist device (LVAD) as destination therapy. Patients undergoing LVAD implantation as destination therapy at the Mayo Clinic, Rochester, Minnesota, from February 2007 to June 2012, were included in this study. Frailty was assessed using the deficit index (31 impairments, disabilities and comorbidities) and defined as the proportion of deficits present. We divided patients based on tertiles of the deficit index (>0.32 = frail, 0.23 to 0.32 = intermediate frail, <0.23 = not frail). Cox proportional hazard regression models were used to examine the association between frailty and death. Patients were censored at death or last follow-up through October 2013. Among 99 patients (mean age 65 years, 18% female, 55% with ischemic heart failure), the deficit index ranged from 0.10 to 0.65 (mean 0.29). After a mean follow-up of 1.9 ± 1.6 years, 79% of the patients had been rehospitalized (range 0 to 17 hospitalizations, median 1 per person) and 45% had died. Compared with those who were not frail, patients who were intermediate frail (adjusted HR 1.70, 95% CI 0.71 to 4.31) and frail (HR 3.08, 95% CI 1.40 to 7.48) were at increased risk for death (p for trend = 0.004). The mean (SD) number of days alive out of hospital the first year after LVAD was 293 (107) for not frail, 266 (134) for intermediate frail and 250 (132) for frail patients. Frailty before destination LVAD implantation is associated with increased risk of death and may represent a significant patient selection consideration. Copyright © 2014 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

Ultracompact, completely implantable permanent use electromechanical ventricular assist device and total artificial heart.

PubMed

Honda, N; Inamoto, T; Nogawa, M; Takatani, S

1999-03-01

An ultracompact, completely implantable permanent use electromechanical ventricular assist device (VAD) and total artificial heart (TAH) intended for 50-60 kg size patients have been developed. The TAH and VAD share a miniature electromechanical actuator that comprises a DC brushless motor and a planetary roller screw. The rotational force of the motor is converted into the rectilinear force of the roller screw to actuate the blood pump. The TAH is a one piece design with left and right pusher plate type blood pumps sandwiching an electromechanical actuator. The VAD is one half of the TAH with the same actuator but a different pump housing and a backplate. The blood contacting surfaces, including those of the flexing diaphragm and pump housing, of both the VAD and TAH were made of biocompatible polyurethane. The diameter, thickness, volume, and weight of the VAD are 90 mm, 56 mm, 285 cc, and 380 g, respectively, while those of the TAH are 90 mm, 73 mm, 400 cc, and 440 g, respectively. The design stroke volume of both the VAD and TAH is 60 cc with the stroke length being 12 mm. The stroke length and motor speed are controlled solely based on the commutation signals of the motor. An in vitro study revealed that a maximum pump flow of 7.5 L/min can be obtained with a pump rate of 140 bpm against a mean afterload of 100 mm Hg. The power requirement ranged from 4 to 6 W to deliver a 4-5 L/min flow against a 100 mm Hg afterload with the electrical-to-hydraulic efficiency being 19-20%. Our VAD and TAH are the smallest of the currently available devices and suitable for bridge to transplant application as well as for permanent circulatory support of 50-60 kg size patients.

Costs and reimbursement gaps after implementation of third-generation left ventricular assist devices.

PubMed

Mishra, Vinod; Geiran, Odd; Fiane, Arnt E; Sørensen, Gro; Andresen, Sølvi; Olsen, Ellen K; Khushi, Ishtiaq; Hagen, Terje P

2010-01-01

The purpose of this study was to compare and contrast total hospital costs and subsequent reimbursement of implementing a new program using a third-generation left ventricular assist device (LVAD) in Norway. Between July 2005 and March 2008, the total costs of treatment for 9 patients were examined. Costs were calculated for three periods-the pre-implantation LVAD phase, the LVAD implantation phase and the post-implantation LVAD phase-as well as for total hospital care. Patient-specific costs were obtained prospectively from patient records and included personnel resources, medication, blood products, blood chemistry and microbiology, imaging, and procedure costs including operating room costs. Overhead costs were registered retrospectively and allocated to the specific patient by pre-defined allocation keys. Finally, patient-specific costs and overhead costs were aggregated into total patient costs. The average total patient cost in 2007 U.S. dollars was $735,342 and the median was $613,087 (range $342,581 to $1,256,026). The mean length of stay was 77 days (range 40 to 127 days). For the LVAD implantation phase, the mean cost was $457,795 and median cost was $458,611 (range $246,239 to $677,680). The mean length of stay for the LVAD implantation phase was 55 days (range 25 to 125 days). The diagnosis-related group (DRG) reimbursement (2007) was $143,192. There is significant discrepancy between actual hospital costs and the current Norwegian DRG reimbursement for the LVAD procedure. This discrepancy can be partly explained by excessive costs related to the introduction of a new program with new technology. Costly innovations should be considered in price setting of reimbursement for novel technology. Copyright (c) 2010 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

Experience of a patient with an extracorporeal ventricular assist system who participated in a sleepover program.

PubMed

Gon, Shigeyoshi; Suematsu, Yoshihito; Morizumi, Sei; Shimizu, Tsuyoshi

2011-09-01

A 19-year-old woman suffered fulminant myocarditis owing to a mycoplasma infection and was inserted with an intra-aortic balloon pump and a percutaneous cardiopulmonary support. Antibiotics and gamma globulin were administered, however, the patient's cardiac function did not recover, and the TOYOBO ventricular assist device (VAD) was implanted. She had rehabilitation training such as maintaining a standing position at the bedside and walking in the hospital, and a hospital outing program to a family restaurant was conducted two times with the VAD. The patient wished to attend the coming-of-age ceremony in Tachikawa city, which is 3 h away from our hospital by car. Therefore, we planned the program including a night stay at her home. The patient and her family fully understood the risks and wished to participate in the sleepover program. In preparing for the sleepover, the patient and her family learned to operate the VAD, and she was able to move to the lavatory and through the house with the help of only her family. A physician and a clinical engineer stayed at her house for infusion of antibiotics and management of sudden changes. There was no adverse event. In Japan, the community support of patients with VAD is not yet established, and we hope that our experience becomes a help to support return to society for patients with VAD.

Long-Term Durability Test for the Left Ventricular Assist System EVAHEART under the Physiologic Pulsatile Load.

PubMed

Kitano, Tomoya; Iwasaki, Kiyotaka

The EVAHEART Left Ventricular Assist System (LVAS) was designed for the long-term support of a patient with severe heart failure. It has an original water lubrication system for seal and bearing and wear on these parts was considered one of its critical failure modes. A durability test focusing on wear was designed herein. We developed a mock loop, which generates a physiologic pulsatile flow and is sufficiently durable for a long-term test. The pulsatile load and the low fluid viscosity enable the creation of a severe condition for the mechanical seal. A total of 18 EVAHEART blood pumps completed 2 years of operation under the pulsatile condition without any failure. It indicated the EVAHEART blood pump had a greater than 90% reliability with a 88% confidence level. The test was continued with six blood pumps and achieved an average of 8.6 years, which was longer than the longest clinical use in Japan. The test result showed that no catastrophic, critical, marginal, or minor failures of the blood pump or their symptoms were observed. The seal performance was maintained after the test. Moreover, the surface roughness did not change, which showed any burn or abnormal wear occurred. The original water lubrication system equipped in EVAHEART LVAS prevent severe wear on the seal and the bearing, and it can be used in the bridge to transplant and destination therapy.

In vivo evaluation of zirconia ceramic in the DexAide right ventricular assist device journal bearing.

PubMed

Saeed, Diyar; Shalli, Shanaz; Fumoto, Hideyuki; Ootaki, Yoshio; Horai, Tetsuya; Anzai, Tomohiro; Zahr, Roula; Horvath, David J; Massiello, Alex L; Chen, Ji-Feng; Dessoffy, Raymond; Catanese, Jacquelyn; Benefit, Stephen; Golding, Leonard A R; Fukamachi, Kiyotaka

2010-06-01

Zirconia is a ceramic with material properties ideal for journal bearing applications. The purpose of this study was to evaluate the use of zirconium oxide (zirconia) as a blood journal bearing material in the DexAide right ventricular assist device. Zirconia ceramic was used instead of titanium to manufacture the DexAide stator housing without changing the stator geometry or the remaining pump hardware components. Pump hydraulic performance, journal bearing reliability, biocompatibility, and motor efficiency data of the zirconia stator were evaluated in six chronic bovine experiments for 14-91 days and compared with data from chronic experiments using the titanium stator. Pump performance data including average in vivo pump flows and speeds using a zirconia stator showed no statistically significant difference to the average values for 16 prior titanium stator in vivo studies, with the exception of a 19% reduction in power consumption. Indices of hemolysis were comparable for both stator types. Results of coagulation assays and platelet aggregation tests for the zirconia stator implants showed no device-induced increase in platelet activation. Postexplant evaluation of the zirconia journal bearing surfaces showed no biologic deposition in any of the implants. In conclusion, zirconia ceramic can be used as a hemocompatible material to improve motor efficiency while maintaining hydraulic performance in a blood journal bearing application.

The overloaded right heart and ventricular interdependence.

PubMed

Naeije, Robert; Badagliacca, Roberto

2017-10-01

The right and the left ventricle are interdependent as both structures are nested within the pericardium, have the septum in common and are encircled with common myocardial fibres. Therefore, right ventricular volume or pressure overloading affects left ventricular function, and this in turn may affect the right ventricle. In normal subjects at rest, right ventricular function has negligible interaction with left ventricular function. However, the right ventricle contributes significantly to the normal cardiac output response to exercise. In patients with right ventricular volume overload without pulmonary hypertension, left ventricular diastolic compliance is decreased and ejection fraction depressed but without intrinsic alteration in contractility. In patients with right ventricular pressure overload, left ventricular compliance is decreased with initial preservation of left ventricular ejection fraction, but with eventual left ventricular atrophic remodelling and altered systolic function. Breathing affects ventricular interdependence, in healthy subjects during exercise and in patients with lung diseases and altered respiratory system mechanics. Inspiration increases right ventricular volumes and decreases left ventricular volumes. Expiration decreases both right and left ventricular volumes. The presence of an intact pericardium enhances ventricular diastolic interdependence but has negligible effect on ventricular systolic interdependence. On the other hand, systolic interdependence is enhanced by a stiff right ventricular free wall, and decreased by a stiff septum. Recent imaging studies have shown that both diastolic and systolic ventricular interactions are negatively affected by right ventricular regional inhomogeneity and prolongation of contraction, which occur along with an increase in pulmonary artery pressure. The clinical relevance of these observations is being explored. Published on behalf of the European Society of Cardiology. All rights

Management of intracranial hemorrhage in patients with left ventricular assist devices.

PubMed

Wilson, Thomas J; Stetler, William R; Al-Holou, Wajd N; Sullivan, Stephen E; Fletcher, Jeffrey J

2013-05-01

The authors conducted a study to review outcomes and management in patients in whom intracranial hemorrhage (ICH) develops during left ventricular assist device (LVAD) therapy. This retrospective cohort study included all adult patients (18 years of age or older) at a single institution who underwent placement of an LVAD between January 1, 2003, and March 1, 2012. The authors conducted a detailed medical chart review, and data were abstracted to assess outcomes in patients in whom ICH developed compared to those in patients in whom ICH did not develop; to compare management of antiplatelet agents and anticoagulation with outcomes; to describe surgical management employed and outcomes achieved; to compare subtypes of ICH (intraparenchymal, subdural, and subarachnoid hemorrhage) and their outcomes; and to determine any predictors of outcome. During the study period, 330 LVADs were placed and 36 patients developed an ICH (traumatic subarachnoid hemorrhage in 10, traumatic subdural hematoma in 8, spontaneous intraventricular hemorrhage in 1, and spontaneous intraparenchymal hemorrhage in 17). All patients were treated with aspirin and warfarin at the time of presentation. With suspension of these agents, no thromboembolic events or pump failures were seen and no delayed rehemorrhages occurred after resuming these medications. Intraparenchymal hemorrhages had the worst outcomes, with a 30-day mortality rate in 59% compared with a 30-day mortality rate of 0% in patients with traumatic subarachnoid hemorrhages and 13% in those with traumatic subdural hematomas. Five patients with intraparenchymal hemorrhages were managed with surgical intervention, 4 of whom died within 60 days. The only factor found to be predictive of outcome was initial Glasgow Coma Scale score. No patients with a Glasgow Coma Scale score less than 11 survived beyond 30 days. Overall, the development of an ICH significantly reduced survival compared with the natural history of patients on LVAD therapy

Barratt assists Drew with EMU

NASA Image and Video Library

2011-02-28

ISS026-E-031000 (28 Feb. 2011) --- Attired in his Extravehicular Mobility Unit (EMU) spacesuit, NASA astronaut Alvin Drew, STS-133 mission specialist, enters the International Space Station?s Quest airlock as the mission?s first spacewalk draws to a close. NASA astronaut Michael Barratt, mission specialist, assisted Drew. Photo credit: NASA or National Aeronautics and Space Administration

Computational Hemodynamics Involving Artificial Devices

NASA Technical Reports Server (NTRS)

Kwak, Dochan; Kiris, Cetin; Feiereisen, William (Technical Monitor)

2001-01-01

This paper reports the progress being made towards developing complete blood flow simulation capability in human, especially, in the presence of artificial devices such as valves and ventricular assist devices. Devices modeling poses unique challenges different from computing the blood flow in natural hearts and arteries. There are many elements needed such as flow solvers, geometry modeling including flexible walls, moving boundary procedures and physiological characterization of blood. As a first step, computational technology developed for aerospace applications was extended in the recent past to the analysis and development of mechanical devices. The blood flow in these devices is practically incompressible and Newtonian, and thus various incompressible Navier-Stokes solution procedures can be selected depending on the choice of formulations, variables and numerical schemes. Two primitive variable formulations used are discussed as well as the overset grid approach to handle complex moving geometry. This procedure has been applied to several artificial devices. Among these, recent progress made in developing DeBakey axial flow blood pump will be presented from computational point of view. Computational and clinical issues will be discussed in detail as well as additional work needed.

Extraction of the human cerebral ventricular system from MRI: inclusion of anatomical knowledge and clinical perspective

NASA Astrophysics Data System (ADS)

Aziz, Aamer; Hu, Qingmao; Nowinski, Wieslaw L.

2004-04-01

The human cerebral ventricular system is a complex structure that is essential for the well being and changes in which reflect disease. It is clinically imperative that the ventricular system be studied in details. For this reason computer assisted algorithms are essential to be developed. We have developed a novel (patent pending) and robust anatomical knowledge-driven algorithm for automatic extraction of the cerebral ventricular system from MRI. The algorithm is not only unique in its image processing aspect but also incorporates knowledge of neuroanatomy, radiological properties, and variability of the ventricular system. The ventricular system is divided into six 3D regions based on the anatomy and its variability. Within each ventricular region a 2D region of interest (ROI) is defined and is then further subdivided into sub-regions. Various strict conditions that detect and prevent leakage into the extra-ventricular space are specified for each sub-region based on anatomical knowledge. Each ROI is processed to calculate its local statistics, local intensity ranges of cerebrospinal fluid and grey and white matters, set a seed point within the ROI, grow region directionally in 3D, check anti-leakage conditions and correct growing if leakage occurs and connects all unconnected regions grown by relaxing growing conditions. The algorithm was tested qualitatively and quantitatively on normal and pathological MRI cases and worked well. In this paper we discuss in more detail inclusion of anatomical knowledge in the algorithm and usefulness of our approach from clinical perspective.

Recent progress in the development of Terumo implantable left ventricular assist system.

PubMed

Nojiri, C; Kijima, T; Maekawa, J; Horiuchi, K; Kido, T; Sugiyama, T; Mori, T; Sugiura, N; Asada, T; Shimane, H; Ozaki, T; Suzuki, M; Akamatsu, T; Akutsu, T

1999-01-01

The research group of the Terumo Corporation, the NTN Corporation, and Setsunan University (T. Akamatsu) has been developing an implantable left ventricular assist system (ILVAS) featuring a centrifugal blood pump with a magnetically suspended impeller (MSCP). The impeller of the MSCP is suspended by a magnetic bearing, providing contact-free rotation of the impeller inside the pump housing. Thus the MSCP is expected to provide years of long-term durability. Ex vivo chronic sheep experiments using the extracorporeal model (Model I) demonstrated long-term durability, nonthrombogenicity, and a low hemolysis rate (plasma free Hb <6 mg/dl) for more than 2 years. The prototype implantable model (Model II; 196 ml, 400 g) was evaluated ex vivo in 2 sheep and intrathoracically implanted in a small sheep (45 kg). These experiments were terminated at 70, 79, and 17 days, respectively, because of blood leakage through the connector system within the housing of Model II. There was no thrombus formation on the retrieved pump surfaces. A new connector system was introduced to the Model II pump (modified Model II), and the pump was intrathoracically implanted in a sheep. Pump flow rate was maintained at 3-7 L/min at 1700-1800 rpm. The temperature elevation on the surfaces of the motor and the electromagnet inside the pump casing was kept less than 6 degrees C. The temperature of the tissue adjacent to the pump casing became normal 10 days postoperatively. The sheep survived for more than 5 months without any sign of mechanical failure or thromboembolic complication. In vitro real-time endurance tests of motor bearings made of stainless steel and silicone nitride have been conducted for more than 1 year without any sign of bearing wear. The next prototype system (Model III), with an implantable controller and a new MSCP with reduced input power, has been developed with a view toward a totally implantable LVAS.

NASA'S Changing Role in Technology Development and Transfer

NASA Technical Reports Server (NTRS)

Griner, Carolyn S.; Craft, Harry G., Jr.

1997-01-01

National Aeronautics and Space Administration NASA has historically had to develop new technology to meet its mission objectives. The newly developed technologies have then been transferred to the private sector to assist US industry's worldwide competitiveness and thereby spur the US economy. The renewed emphasis by the US Government on a proactive technology transfer approach has produced a number of contractual vehicles that assist technology transfer to industrial, aerospace and research firms. NASA's focus has also been on leveraging the shrinking space budget to accomplish "more with less." NASA's cooperative agreements and resource sharing agreements are measures taken to achieve this goal, and typify the changing role of government technology development and transfer with industry. Large commercial partnerships with aerospace firms, as typified by the X-33 and X-34 Programs, are evolving. A new emphasis on commercialization in the Small Business Innovative Research and Dual Use programs paves the way for more rapid commercial application of new technologies developed for NASA.

Implantable Cardioverter-Defibrillators in Patients With a Continuous-Flow Left Ventricular Assist Device: An Analysis of the INTERMACS Registry.

PubMed

Clerkin, Kevin J; Topkara, Veli K; Demmer, Ryan T; Dizon, Jose M; Yuzefpolskaya, Melana; Fried, Justin A; Mai, Xingchen; Mancini, Donna M; Takeda, Koji; Takayama, Hiroo; Naka, Yoshifumi; Colombo, Paolo C; Garan, A Reshad

2017-12-01

This study sought to determine if the presence of implantable cardioverter-defibrillators (ICD) provided a mortality benefit during continuous-flow left ventricular assist device (LVAD) support. An ICD decreases mortality in selected patients with advanced heart failure and have been associated with reduced mortality in patients with pulsatile LVAD. However, it is unclear whether that benefit extends to patients with a contemporary continuous-flow LVAD. Propensity score matching was used to generate a cohort of patients with similar baseline characteristics. The primary outcome was freedom from death during LVAD support. Secondary endpoints included freedom from unexpected death, likelihood of transplantation and recovery, and adverse events. Among 16,384 eligible patients in the Interagency Registry for Mechanically Assisted Circulatory Support registry, 2,209 patients with an ICD and 2,209 patients without one had similar propensity scores and were included. The presence of an ICD was associated with an increased mortality risk (hazard ratio: 1.20; 95% confidence interval [CI]: 1.04 to 1.39; p = 0.013) and an increased risk of unexpected death during device support (HR: 1.33; 95% CI: 1.03 to 1.71; p = 0.03). Patients with an ICD were more likely to undergo transplantation (HR: 1.16; 95% CI: 0.99 to 1.35; p = 0.06) and less likely to have LVAD explant for recovery (HR: 0.53, 95% CI: 0.29 to 0.98; p = 0.04). Patients with an ICD had a higher rate of treated ventricular arrhythmias (rate ratio: 1.27; 95% CI: 1.10 to 1.48; p = 0.001) and rehospitalization (rate ratio: 1.08; 95% CI: 1.04 to 1.12; p < 0.0001), but rates of hemorrhagic stroke were similar (rate ratio: 1.01; 95% CI: 0.81 to 1.26; p = 0.98). Among patients with a continuous flow LVAD, the presence of an ICD was not associated with reduced mortality. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Surgery for ventricular tachycardia in patients undergoing surgical ventricular restoration: the Karolinska approach.

PubMed

Sartipy, Ulrik; Albåge, Anders; Insulander, Per; Lindblom, Dan

2007-09-01

This article presents a review on the efficacy of surgical ventricular restoration and direct surgery for ventricular tachycardia in patients with left ventricular aneurysm or dilated ischemic cardiomyopathy. The procedure includes a non-electrophysiologically guided subtotal endocardiectomy and cryoablation in addition to endoventricular patch plasty of the left ventricle. Coronary artery bypass surgery and mitral valve repair are performed concomitantly as needed. In our experience, this procedure yielded a 90% success rate in terms of freedom from spontaneous ventricular tachycardia, with an early mortality rate of 3.8%. A practical guide to the pre- and postoperative management of these patients is provided.

Body position and activity, but not heart rate, affect pump flows in patients with continuous-flow left ventricular assist devices.

PubMed

Muthiah, Kavitha; Gupta, Sunil; Otton, James; Robson, Desiree; Walker, Robyn; Tay, Andre; Macdonald, Peter; Keogh, Anne; Kotlyar, Eugene; Granger, Emily; Dhital, Kumud; Spratt, Phillip; Jansz, Paul; Hayward, Christopher S

2014-08-01

The aim of this study was to determine the contribution of pre-load and heart rate to pump flow in patients implanted with continuous-flow left ventricular assist devices (cfLVADs). Although it is known that cfLVAD pump flow increases with exercise, it is unclear if this increment is driven by increased heart rate, augmented intrinsic ventricular contraction, or enhanced venous return. Two studies were performed in patients implanted with the HeartWare HVAD. In 11 patients, paced heart rate was increased to approximately 40 beats/min above baseline and then down to approximately 30 beats/min below baseline pacing rate (in pacemaker-dependent patients). Ten patients underwent tilt-table testing at 30°, 60°, and 80° passive head-up tilt for 3 min and then for a further 3 min after ankle flexion exercise. This regimen was repeated at 20° passive head-down tilt. Pump parameters, noninvasive hemodynamics, and 2-dimensional echocardiographic measures were recorded. Heart rate alteration by pacing did not affect LVAD flows or LV dimensions. LVAD pump flow decreased from baseline 4.9 ± 0.6 l/min to approximately 4.5 ± 0.5 l/min at each level of head-up tilt (p < 0.0001 analysis of variance). With active ankle flexion, LVAD flow returned to baseline. There was no significant change in flow with a 20° head-down tilt with or without ankle flexion exercise. There were no suction events. Centrifugal cfLVAD flows are not significantly affected by changes in heart rate, but they change significantly with body position and passive filling. Previously demonstrated exercise-induced changes in pump flows may be related to altered loading conditions, rather than changes in heart rate. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

NASA Helps Build Colorado Economy

NASA Image and Video Library

2010-12-13

Colorado State Governor Bill Ritter delivers remarks at the Colorado State Capitol in Denver on Monday, Dec. 13, 2010, prior to the signing of an agreement with NASA that creates a Technology Acceleration Program and Regional Innovation Cluster for Aerospace and Clean Energy. A manufacturing park focused on rapid new product development and production will be developed to assist growing Colorado businesses while promoting the commercialization of technology developed for the space program. Photo Credit: (NASA/Bill Ingalls)

[The reasonable use of right ventricular protection strategy in right ventricular outflow tract reconstruction].

PubMed

Zhang, Y; Yuan, H Y; Liu, X B; Wen, S S; Xu, G; Cui, H J; Zhuang, J; Chen, J M

2018-06-01

As a result of right ventricular outflow tract reconstruction, which is the important and basic step of complex cardiac surgery, the blood flow of right ventricular outflow tract is unobstructed, while pulmonary valve regurgitation and right heart dysfunction could be happened. These problems are often ignored in early days, more and more cases of right heart dysfunction need clinical intervention, which is quite difficult and less effective. How to protect effectively the right ventricular function is the focus. At present main methods to protect the right ventricular function include trying to avoid or reduce length of right ventricular incision, reserving or rebuilding the function of the pulmonary valve, using growth potential material for surgery. The protection of the right ventricular function is a systemic project, it involves many aspects, single measures is difficult to provide complete protection, only the comprehensive use of various protection strategy, can help to improve the long-term prognosis.

NASA Operational Environment Team (NOET) - NASA's key to environmental technology

NASA Technical Reports Server (NTRS)

Cook, Beth

1993-01-01

NOET is a NASA-wide team which supports the research and development community by sharing information both in person and via a computerized network, assisting in specification and standard revisions, developing cleaner propulsion systems, and exploring environmentally compliant alternatives to current processes. NOET's structure, dissemination of materials, electronic information, EPA compliance, specifications and standards, and environmental research and development are discussed.

Assisting Wine Growers

NASA Technical Reports Server (NTRS)

1993-01-01

This video documents efforts at NASA Ames Research Center to assist wine growers in the Napa valley in their fight against a root parasite which is destroying millions of dollars worth of grape crops. NASA researchers are using airborne scanners and remote sensing equipment to detect the parasite before it becomes entrenched, so that growers can treat the harvest to resist infestation.

Preoperative atrial fibrillation increases risk of thromboembolic events after left ventricular assist device implantation.

PubMed

Stulak, John M; Deo, Salil; Schirger, John; Aaronson, Keith D; Park, Soon J; Joyce, Lyle D; Daly, Richard C; Pagani, Francis D

2013-12-01

Because no series has specifically analyzed the impact of preoperative atrial fibrillation (AF) on patients already at higher risk of thromboembolism after implantation of a left ventricular assist device (LVAD), we review our experience with these patients. Between July 2003 and September 2011, 389 patients (308 male) underwent implantation of a continuous flow LVAD at University of Michigan Hospital and Mayo Clinic. Median age at implant was 60 years (range, 18 to 79 years). Preoperative AF was present in 120 patients (31%). Outcomes were analyzed for the association of preoperative AF and postoperative thromboembolic (TE) events defined as stroke, transient ischemic attack, hemolysis, or pump thrombosis. Thromboembolic events occurring within the first 30 days were not counted. One hundred thirty-eight TEs events occurred in 97/389 patients (25%) for an event rate of 0.31 TE events/patient-years of support. Freedom from a TE event in patients with preoperative AF was 62% at 1 year and 46% at 2 years compared with 79% and 72% at 1 and 2 years, respectively, in patients without preoperative AF (p < 0.001). Median survival was 10 months (maximum 7.2 years, total 439 patient-years). Preoperative AF did not decrease late survival at 1 and 2 years after LVAD implant (preop AF: 85% and 70% versus no preop AF: 82% and 70%, respectively; p = 0.55). Patients with preoperative AF have a lower freedom from TE events after LVAD implant. While overall late survival was not significantly reduced in these patients, refinement in anticoagulation strategies after VAD implant may be required. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

NASA Research Announcement Phase 1 Report and Phase 2 Proposal for the Development of a Power Assisted Space Suit Glove Assembly

NASA Technical Reports Server (NTRS)

Cadogan, Dave; Lingo, Bob

1996-01-01

In July of 1996, ILC Dover was awarded Phase 1 of a contract for NASA to develop a prototype Power Assisted Space Suit glove to enhance the performance of astronauts during Extra-Vehicular Activity (EVA). This report summarizes the work performed to date on Phase 1, and details the work to be conducted on Phase 2 of the program. Phase 1 of the program consisted of research and review of related technical sources, concept brainstorming, baseline design development, modeling and analysis, component mock-up testing, and test data analysis. ILC worked in conjunction with the University of Maryland's Space Systems Laboratory (SSL) to develop the power assisted glove. Phase 2 activities will focus on the design maturation and the manufacture of a working prototype system. The prototype will be tested and evaluated in conjunction with existing space suit glove technology to determine the performance enhancement anticipated with the implementation of the power assisted joint technology in space suit gloves.

An electrocardiographic scoring system for distinguishing right ventricular outflow tract arrhythmias in patients with arrhythmogenic right ventricular cardiomyopathy from idiopathic ventricular tachycardia.

PubMed

Hoffmayer, Kurt S; Bhave, Prashant D; Marcus, Gregory M; James, Cynthia A; Tichnell, Crystal; Chopra, Nagesh; Moxey, Laura; Krahn, Andrew D; Dixit, Sanjay; Stevenson, William; Calkins, Hugh; Badhwar, Nitish; Gerstenfeld, Edward P; Scheinman, Melvin M

2013-04-01

Ventricular arrhythmias in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) and idiopathic ventricular tachycardia (VT) can share a left bundle branch block/inferior axis morphology. We previously reported electrocardiogram characteristics during outflow tract ventricular arrhythmias that helped distinguish VT related to ARVD/C from idiopathic VT. To prospectively validate these criteria. We created a risk score by using a derivation cohort. Two experienced electrophysiologists blinded to the diagnosis prospectively scored patients with VT/premature ventricular contractions (PVCs) with left bundle branch block/inferior axis pattern in a validation cohort of 37 ARVD/C tracings and 49 idiopathic VT tracings. All patients with ARVD/C had their diagnosis confirmed based on the revised task force criteria. Patients with idiopathic VT were selected based on structurally normal hearts with documented right ventricular outflow tract VT successfully treated with ablation. The scoring system provides 3 points for sinus rhythm anterior T-wave inversions in leads V1-V3 and during ventricular arrhythmia: 2 points for QRS duration in lead I≥120 ms, 2 points for QRS notching, and 1 point for precordial transition at lead V5 or later. A score of 5 or greater was able to correctly distinguish ARVD/C from idiopathic VT 93% of the time, with a sensitivity of 84%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 91%. We describe a simple scoring algorithm that uses 12-lead electrocardiogram characteristics to effectively distinguish right ventricular outflow tract arrhythmias originating from patients with ARVD/C versus patients with idiopathic VT. Copyright © 2013 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Studies on deflection area vectors of QRS and T and ventricular gradient in right ventricular hypertrophy.

PubMed

Kawaguchi, Y

1985-04-01

QRS deflection area vector (Aqrs), T deflection area vector (At) and ventricular gradient (G) in right ventricular hypertrophy were studied in 53 subjects divided on the basis of cardiac catheterization data into four subgroups; normal controls, mild MS group, right ventricular pressure overload group and right ventricular volume overload group. Aqrs, At and G of the four subgroups were calculated using a microcomputer and compared. Aqrs in right ventricular pressure overload group and volume overload group was shifted to the right and slightly anteriorly from that in normal control group. At in right ventricular pressure overload group and volume overload group was shifted slightly upwards and significantly posteriorly from that in the normal control and mild MS groups. G in right ventricular pressure overload group and volume overload group was shifted to the right and significantly posteriorly from that in normal control and mild MS groups. Using multivariative analysis, we developed criteria for diagnosing right ventricular hypertrophy with At: 0.059At(Z) - 0.0145 [At] - 0.2608 less than or equal to 0. Application of this criteria achieved 82.4% (28 of 34) sensitivity in the patients with right ventricular hypertrophy and 90.9% (10 of 11) specificity in the normal control subjects.

NASA Helps Build Colorado Economy

NASA Image and Video Library

2010-12-13

Colorado Association for Manufacturing and Technology (CAMT) CEO Elaine Thorndike delivers remarks at the Colorado State Capitol in Denver on Monday, Dec. 13, 2010, prior to the signing of an agreement with NASA that creates a Technology Acceleration Program and Regional Innovation Cluster for Aerospace and Clean Energy. A manufacturing park focused on rapid new product development and production will be developed to assist growing Colorado businesses while promoting the commercialization of technology developed for the space program. Photo Credit: (NASA/Bill Ingalls)

Right Ventricular Outflow Tract Tachycardia with Structural Abnormalities of the Right Ventricle and Left Ventricular Diverticulum.

PubMed

Martini, Bortolo; Trevisi, Nicola; Martini, Nicolò; Zhang, Li

2015-01-01

A 43-year-old woman presented to the emergency room with a sustained ventricular tachycardia (VT). ECG showed a QRS in left bundle branch block morphology with inferior axis. Echocardiography, ventricular angiography, and cardiac magnetic resonance imaging (CMRI) revealed a normal right ventricle and a left ventricular diverticulum. Electrophysiology studies with epicardial voltage mapping identified a large fibrotic area in the inferolateral layer of the right ventricular wall and a small area of fibrotic tissue at the anterior right ventricular outflow tract. VT ablation was successfully performed with combined epicardial and endocardial approaches.

Right Ventricular Outflow Tract Tachycardia with Structural Abnormalities of the Right Ventricle and Left Ventricular Diverticulum

PubMed Central

Martini, Bortolo; Trevisi, Nicola; Martini, Nicolò; Zhang, Li

2015-01-01

A 43-year-old woman presented to the emergency room with a sustained ventricular tachycardia (VT). ECG showed a QRS in left bundle branch block morphology with inferior axis. Echocardiography, ventricular angiography, and cardiac magnetic resonance imaging (CMRI) revealed a normal right ventricle and a left ventricular diverticulum. Electrophysiology studies with epicardial voltage mapping identified a large fibrotic area in the inferolateral layer of the right ventricular wall and a small area of fibrotic tissue at the anterior right ventricular outflow tract. VT ablation was successfully performed with combined epicardial and endocardial approaches. PMID:26509086

Noninvasive Assessment of Left Ventricular Assist Devices with Cardiovascular Computed Tomography and Impact on Management

PubMed Central

Raman, Subha V.; Sahu, Anurag; Merchant, Ali Z.; Louis, Louis B.; Firstenberg, Michael S.; Sun, Benjamin

2009-01-01

Background Left ventricular assist devices (LVADs) provide a bridge to recovery or heart transplantation, but require serial assessment. Echocardiographic approaches may be limited by device artifact and acoustic window. Cardiovascular computed tomography (CCT) provides noninvasive imaging of LVADs, yet no study has evaluated CCT’s impact on clinical care. We evaluated the diagnostic findings and clinical impact of CCT for noninvasive assessment of patients with LVADs. Methods CCT examinations performed between 2005 and 2008 in patients with LVADs were identified. Acquisitions were completed on the identical 64 detector-row scanner with intravenous contrast administration; electrocardiographic gating was used in patients with pulsatile devices, while peripheral pulse gating was used in patients with continuous-flow devices. Comparison was made between CCT results and 30-day outcomes, including echocardiographic and intraoperative findings. Results Thirty-two CCT examinations from 28 patients were reviewed. Indications included evaluation of low cardiac output symptoms, assessment of cannula position, low flow reading on the LVAD, and surgical planning. CCT identified critical findings in 6 patients including thrombosis and inlet cannula malposition, all confirmed intraoperatively; one case of intra-LVAD thrombus was missed by CCT. Using intraoperative findings as the gold standard, CCT’s sensitivity was 85% and specificity was 100%. Echocardiographic LVAD evaluation did not correlate with findings on CCT (kappa = −0.29, 95% CI −0.73−0.13). Conclusions This preliminary observational cohort study indicates that noninvasive imaging using CCT of LVADs is feasible and accurate. CCT warrants consideration in the initial evaluation of symptomatic patients with LVADs. PMID:19782594

Is Diabetes Mellitus a Risk Factor for Poor Outcomes after Left Ventricular Assist Device Placement?

PubMed

Mohamedali, Burhan; Yost, Gardner; Bhat, Geetha

2017-04-01

Diabetes mellitus is associated with adverse outcomes in patients with cardiovascular diseases, including heart failure. Left ventricular assist devices (LVADs) are increasingly used as life-saving therapy for advanced heart failure. The effects of pre-LVAD diabetes on long-term outcomes after LVAD implantation are not well understood. In this study, we retrospectively evaluated the effect of existing diabetes on post-LVAD outcomes. Data on 288 LVAD recipients from 2006 through 2013 were reviewed. Patients were stratified in accordance with their histories of diabetes. Baseline demographic, laboratory, hemodynamic, and echocardiographic information before LVAD placement were reviewed, together with the post-LVAD incidence of major adverse outcomes. Kaplan-Meier analysis and Cox regression analysis were performed. Our cohort comprised 122 patients with diabetes and 166 patients without. The mean glycosylated hemoglobin A 1c level in the diabetes group was 7.4% ± 1.6%. Diabetic patients at baseline had a more adverse medical profile than did nondiabetic patients. There were no differences in major outcomes between the 2 groups other than a higher incidence of hemolysis in the diabetes group: 12 (10%) vs 5 (3%); P =0.02. There was no difference in survival outcomes between the groups. Diabetic patients did not have worse survival or more adverse outcomes than did nondiabetic patients in this study, perhaps because of improved diabetes control, or improvement in biochemical derangements after normalization of cardiac output with LVAD therapy. A diagnosis of diabetes was an independent predictor of hemolysis. Further studies to evaluate the link between hemolysis and diabetes are indicated.

Sleep and daytime sleepiness of patients with left ventricular assist devices: a longitudinal pilot study.

PubMed

Casida, Jesus M; Davis, Jean E; Brewer, Robert J; Smith, Cheryl; Yarandi, Hossein

2011-06-01

No empirical longitudinal data on sleep and daytime sleepiness patterns in patients with an implantable left ventricular assist device (LVAD) exist. (1) To describe the sleep patterns (sleep onset latency, sleep efficiency, sleep fragmentation index, total sleep time, and wake after sleep onset), sleep quality, and daytime sleepiness variables and (2) to determine the change in the pattern of these variables before and up to 6 months after LVAD implantation. A longitudinal descriptive repeated-measures design was used. Patients wore wrist actigraphs (AW64 Actiwatch), which objectively measured sleep, for 3 consecutive days and nights before LVAD implant and at the first and second week and first, third, and sixth month after implantation. During these periods, patients also completed questionnaires on sleep quality and daytime sleepiness. Patients-Twelve of 15 patients completed the 6-month data. Data were analyzed by using descriptive statistics and repeated-measures analysis of variance. We found long sleep onset latencies and low sleep efficiency across time periods. High sleep fragmentation index was noted at baseline and 1 week after LVAD. Short total sleep times, long wake-after-sleep-onset durations, and poor sleep quality were evident at baseline and persisted up to 6 months after LVAD implantation. Low alertness level, a manifestation of sleepiness, was common during late morning to early evening hours. However, only sleep efficiency and wake after sleep onset showed significant changes in pattern (P < .05). Sleep disturbance and daytime sleepiness may be prevalent before and up to 6 months after LVAD implantation, warranting further investigation.

Concomitant tricuspid valve repair or replacement during left ventricular assist device implant demonstrates comparable outcomes in the long term.

PubMed

Deo, Salil V; Hasin, Tal; Altarabsheh, Salah E; McKellar, Stephen H; Shah, Ishan K; Durham, Lucian; Stulak, John M; Daly, Richard C; Park, Soon J; Joyce, Lyle D

2012-11-01

Severe tricuspid regurgitation (TR) is present in nearly half the patients undergoing implant of a left ventricular assist device (LVAD) and its correction confers better long-term outcome. To compare the early and late results of tricuspid valve repair (TVrpr) or replacement (TVR) with LVAD implant. Sixty-four from a cohort of 126 patients had a concomitant tricuspid valve procedure; 48 (75%) underwent a TVrpr whereas 16 (25%) had TVR. All preoperative hemodynamic parameters including the mean TR grade (TVrpr; 3.6 vs. TVR; 3.7) were comparable (p = 0.7). The mean TR grade was 1.6 ± 1.5 for the remaining 62 patients who did not have a concomitant tricuspid valve procedure, with 4/62 (6%) having severe TR (p < 0.0001). Cardiopulmonary bypass time was longer for patients undergoing TVR (p = 0.01). There was a significant reduction in right atrial pressure for the entire cohort (p < 0.01) and the postoperative right atrial pressure was not statistically different between TVrpr (13.6 ± 4.6) and TVR (11.6 ± 4.3; p = 0.6. Postoperative intensive care unit stay was comparable as was the duration of inotropic support (p = 0.5) or need for temporary right ventricular mechanical support. In-hospital mortality (12%) was not different between groups. The mean time for LVAD support was 12.3 ± 9.71 months and the last transthoracic echocardiographic examination was performed at mean intervals of 13.8 ± 10.8 months (TVrpr) and 11.8 ± 7.6 months (TVR; p = 0.47). Reduction in TR grade was similar between groups (p = 0.27). Late mortality (p = 1.00) was comparable in both groups. Using log-rank analysis, there was no significant difference in the estimated survival between TVrpr and TVR (p = 0.88). TVrpr repair at the time of LVAD implant is effective in correcting TR even at the end of one year of follow-up. The choice to repair or replace does not affect the clinical outcome. © 2012 Wiley Periodicals, Inc.

NASA Office of Small and Disadvantaged Business Utilization

NASA Technical Reports Server (NTRS)

2001-01-01

The Office of Small and Disadvantaged Business Utilization (OSDBU) within NASA promotes the utilization of small, disadvantaged, and women-owned small businesses in compliance with Federal laws, regulations, and policies. We assist such firms in obtaining contracts and subcontracts with NASA and its prime contractors. The OSDBU also facilitates the participation of small businesses in NASA's technology transfer and commercialization activities. Our driving philosophy is to consider small businesses as our products. Our customers are the NASA Enterprises, Field Centers, Functional Staff Offices, major prime contractors, and other large institutions. We hone the skills of our products to make them marketable to our customers in the performance of NASA missions.

A large left ventricular thrombus.

PubMed

Patanè, Salvatore; Marte, Filippo

2009-06-26

The discovery of a left ventricular mass obliges the clinician to perform a differential diagnosis including tumour or lipoma versus thrombus and its assessment presents important clinical implications. Dilated cardiomyopathy has been associated with left ventricular thrombosis which leads to substantial morbidity and mortality as a site for peripheral emboli. There are some studies on patients with dilated cardiomyopathy showing altered hemostasis and platelet behavior despite sinus rhythm. An increased incidence of thromboembolism is also well recognized in patients with left ventricular systolic dysfunction complicating history of myocardial infarction. Clinical dilemmas in treating left ventricular thrombus have been described too. We present a case of a large mobile left ventricular thrombus in a 71-year-old Italian man with dilated cardiomyopathy and history of myocardial infarction.

NASA Helps Build Colorado Economy

NASA Image and Video Library

2010-12-13

Representative from U.S. Senator Udall's office Jimmy Haugue reads remarks from U.S. Senator Udall at the Colorado State Capitol in Denver on Monday, Dec. 13, 2010, prior to the signing of an agreement with NASA that creates a Technology Acceleration Program and Regional Innovation Cluster for Aerospace and Clean Energy. A manufacturing park focused on rapid new product development and production will be developed to assist growing Colorado businesses while promoting the commercialization of technology developed for the space program. Photo Credit: (NASA/Bill Ingalls)

NASA Helps Build Colorado Economy

NASA Image and Video Library

2010-12-13

NIST MEP Director Roger Kilmer delivers remarks at the Colorado State Capitol in Denver on Monday, Dec. 13, 2010, prior to the signing of an agreement between the Colorado Association for Manufacturing and Technology (CAMT) and NASA that creates a Technology Acceleration Program and Regional Innovation Cluster for Aerospace and Clean Energy. A manufacturing park focused on rapid new product development and production will be developed to assist growing Colorado businesses while promoting the commercialization of technology developed for the space program. Photo Credit: (NASA/Bill Ingalls)

Pre- and post-operative risk factors associated with cerebrovascular accidents in patients supported by left ventricular assist device. -Single center's experience in japan-.

PubMed

Nakajima, Ikutaro; Kato, Tomoko S; Komamura, Kazuo; Takahashi, Ayako; Oda, Noboru; Sasaoka, Taro; Asakura, Masanori; Hashimura, Kazuhiko; Kitakaze, Masafumi

2011-01-01

Cerebrovascular accident (CVA) is a major adverse event following left ventricular assist device (LVAD) surgery. This study investigates pre- and post-operative factors associated with CVA in this population. A total of 118 consecutive patients who underwent LVAD surgery at our institution between April 1994 and April 2009 were retrospectively reviewed. Clinical characteristics, hemodynamic data, and laboratory indexes associated with CVA after LVAD surgery were analyzed. In total, 57 (48.3%) patients developed CVA 133.5 ± 184.7 days after surgery. The combination of baseline heart disease, type of LVAD surgery, mean right atrial pressure (mRA), serum total bilirubin and total protein concentration, and right ventricular end-diastolic dimension (RVEDd) was associated with CVA at any time after LVAD surgery, with a discriminant probability of 718%. With regard to CVA development later than 3 months after surgery, the combination of mRA and RVEDd before surgery [odds ratio (OR), 1.24, 1.20; 95% confidential interval (CI), 1.07-1.42, 1.06-1.34; P = 0.004, P = 0.006, respectively], positive blood culture, and C-reactive protein after surgery (OR, 7.66, 2.19; 95%CI, 1.50-39.0, 1.47-3.25; P = 0.015, P < 0.0001, respectively) was associated with CVA with a discriminant probability of 85.9%. Patients' general condition including malnutrition, in addition to device selection, contributed to overall CVA development after surgery. In the chronic phase after surgery, pre-LVAD right heart failure and post-LVAD systemic infection were highly associated with CVA development.

Right ventricular pressure response to exercise in adults with isolated ventricular septal defect closed in early childhood.

PubMed

Moller, Thomas; Lindberg, Harald; Lund, May Brit; Holmstrom, Henrik; Dohlen, Gaute; Thaulow, Erik

2018-06-01

We previously demonstrated an abnormally high right ventricular systolic pressure response to exercise in 50% of adolescents operated on for isolated ventricular septal defect. The present study investigated the prevalence of abnormal right ventricular systolic pressure response in 20 adult (age 30-45 years) patients who underwent surgery for early ventricular septal defect closure and its association with impaired ventricular function, pulmonary function, or exercise capacity. The patients underwent cardiopulmonary tests, including exercise stress echocardiography. Five of 19 patients (26%) presented an abnormal right ventricular systolic pressure response to exercise ⩾ 52 mmHg. Right ventricular systolic function was mixed, with normal tricuspid annular plane systolic excursion and fractional area change, but abnormal tricuspid annular systolic motion velocity (median 6.7 cm/second) and isovolumetric acceleration (median 0.8 m/second2). Left ventricular systolic and diastolic function was normal at rest as measured by the peak systolic velocity of the lateral wall and isovolumic acceleration, early diastolic velocity, and ratio of early diastolic flow to tissue velocity, except for ejection fraction (median 53%). The myocardial performance index was abnormal for both the left and right ventricle. Peak oxygen uptake was normal (mean z score -0.4, 95% CI -2.8-0.3). There was no association between an abnormal right ventricular systolic pressure response during exercise and right or left ventricular function, pulmonary function, or exercise capacity. Abnormal right ventricular pressure response is not more frequent in adult patients compared with adolescents. This does not support the theory of progressive pulmonary vascular disease following closure of left-to-right shunts.

Pulse Oximeter Derived Blood Pressure Measurement in Patients With a Continuous Flow Left Ventricular Assist Device.

PubMed

Hellman, Yaron; Malik, Adnan S; Lane, Kathleen A; Shen, Changyu; Wang, I-Wen; Wozniak, Thomas C; Hashmi, Zubair A; Munson, Sarah D; Pickrell, Jeanette; Caccamo, Marco A; Gradus-Pizlo, Irmina; Hadi, Azam

2017-05-01

Currently, blood pressure (BP) measurement is obtained noninvasively in patients with continuous flow left ventricular assist device (LVAD) by placing a Doppler probe over the brachial or radial artery with inflation and deflation of a manual BP cuff. We hypothesized that replacing the Doppler probe with a finger-based pulse oximeter can yield BP measurements similar to the Doppler derived mean arterial pressure (MAP). We conducted a prospective study consisting of patients with contemporary continuous flow LVADs. In a small pilot phase I inpatient study, we compared direct arterial line measurements with an automated blood pressure (ABP) cuff, Doppler and pulse oximeter derived MAP. Our main phase II study included LVAD outpatients with a comparison between Doppler, ABP, and pulse oximeter derived MAP. A total of five phase I and 36 phase II patients were recruited during February-June 2014. In phase I, the average MAP measured by pulse oximeter was closer to arterial line MAP rather than Doppler (P = 0.06) or ABP (P < 0.01). In phase II, pulse oximeter MAP (96.6 mm Hg) was significantly closer to Doppler MAP (96.5 mm Hg) when compared to ABP (82.1 mm Hg) (P = 0.0001). Pulse oximeter derived blood pressure measurement may be as reliable as Doppler in patients with continuous flow LVADs. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Regional Cerebral Oxygen Saturation Level Predicts 30-Day Mortality Rate After Left Ventricular Assist Device Surgery.

PubMed

Ghosal, Soutik; Trivedi, Jaimin; Chen, James; Rogers, Michael P; Cheng, Allen; Slaughter, Mark S; Kong, Maiying; Huang, Jiapeng

2018-06-01

Left ventricular assist device (LVAD) surgery is complex, high risk, and expensive. The authors' hypothesis is baseline regional cerebral oxygen saturation (rSO 2 ) might be a predictor of postoperative clinical outcomes. Retrospective review of 210 consecutive continuous flow LVAD patients between 2008 and 2014. The primary measure is 30-day mortality rate and secondary measures include modified major adverse cardiocerebral events (MACE), length of stay (LOS), and intensive care unit (ICU) stay. Multiple logistic regression models were applied to examine if a binary outcome variable, such as 30-day mortality and MACE, is associated with rSO 2 at baseline. Log-linear model was used to examine whether LOS or ICU stay hours is associated with rSO 2 at baseline. Single institution, academic hospital. Patients who received LVAD surgery ​at Jewish Hospital, Louisville, KY. All patients received LVAD surgery. Cerebral oximetry monitoring was used in both the preoperative and intraoperative periods. The authors found that higher rSO 2 at baseline is associated with lower 30-day mortality with an odds ratio of 0.94 and 95% confidence interval (0.888, 0.995) for every 1% increase of rSO 2 . For secondary outcomes, baseline rSO 2 was not significantly associated with MACE, requirement for postoperative renal failure/dialysis, reoperation for bleeding, and LOS or ICU hours. Regional cerebral oxygen saturation levels at baseline are significantly associated with 30-day mortality after LVAD surgeries. Copyright © 2017 Elsevier Inc. All rights reserved.

Impact of left ventricular assist device speed adjustment on exercise tolerance and markers of wall stress.

PubMed

Hayward, Christopher S; Salamonsen, Robert; Keogh, Anne M; Woodard, John; Ayre, Peter; Prichard, Roslyn; Kotlyar, Eugene; Macdonald, Peter S; Jansz, Paul; Spratt, Phillip

2015-09-01

Left ventricular assist devices are crucial in rehabilitation of patients with end-stage heart failure. Whether cardiopulmonary function is enhanced with higher pump output is unknown. 10 patients (aged 39±16 years, mean±SD) underwent monitored adjustment of pump speed to determine minimum safe low speed and maximum safe high speed at rest. Patients were then randomized to these speed settings and underwent three 6-minute walk tests (6MWT) and symptom-limited cardiopulmonary stress tests (CPX) on separate days. Pump speed settings (low, normal and high) resulted in significantly different resting pump flows of 4.43±0.6, 5.03±0.94, and 5.72±1.2 l/min (P<.001). There was a significant enhancement of pump flows (greater at higher speed settings) with exercise (P<0.05). Increased pump speed was associated with a trend to increased 6MWT distance (P=.10); and CPX exercise time (p=.27). Maximum workload achieved and peak oxygen consumption were significantly different comparing low to high pump speed settings only (P<.05). N-terminal-pro-B-type natriuretic peptide release was significantly reduced at higher pump speed with exercise (P<.01). We have found that alteration of pump speed setting resulted in significant variation in estimated pump flow. The high-speed setting was associated with lower natriuretic hormone release consistent with lower myocardial wall stress. This did not, however, improve exercise tolerance.

The Heartmate III: design and in vivo studies of a maglev centrifugal left ventricular assist device.

PubMed

Loree, H M; Bourque, K; Gernes, D B; Richardson, J S; Poirier, V L; Barletta, N; Fleischli, A; Foiera, G; Gempp, T M; Schoeb, R; Litwak, K N; Akimoto, T; Kameneva, M; Watach, M J; Litwak, P

2001-05-01

A compact implantable centrifugal left ventricular assist device (LVAD) (HeartMate III) featuring a magnetically levitated impeller is under development. The goal of our ongoing work is to demonstrate feasibility, low hemolysis, and low thrombogenicity of the titanium pump in chronic bovine in vivo studies. The LVAD is based on so-called bearingless motor technology and combines pump rotor, drive, and magnetic bearing functions in a single unit. The impeller is rotated (theta z) and levitated with both active (X, Y) and passive (Z, theta x, theta y) suspension. Six prototype systems have been built featuring an implantable titanium pump (69 mm diameter, 30 mm height) with textured blood contacting surfaces and extracorporeal electronics. The pumps were implanted in 9 calves (< or = 100 kg at implant) that were anticoagulated with Coumadin (2.5 < or = INR < or = 4.0) throughout the studies. Six studies were electively terminated (at 27-61 days), 1 study was terminated after the development of severe pneumonia and lung atelectasis (at 27 days) another study was terminated after cardiac arrest (at 2 days) while a final study is ongoing (at approximately 100 days). Mean pump flows ranged from 2 to 7 L/min, except for brief periods of exercise at 6 to 9 L/min. Plasma free hemoglobin ranged from 4 to 10 mg/dl. All measured biochemical indicators of end organ function remained within normal range. The pumps have met performance requirements in all 9 implants with acceptable hemolysis and no mechanical failures.

Single-center experience of the bridge-to-bridge strategy using the Nipro paracorporeal ventricular assist device.

PubMed

Yoshitake, Shuichi; Kinoshita, Osamu; Nawata, Kan; Hoshino, Yasuhiro; Itoda, Yoshifumi; Kimura, Mitsutoshi; Yamauchi, Haruo; Ono, Minoru

2018-06-25

Currently, we use the Nipro paracorporeal VAD (p-VAD) for initial short-term ventricular support, as a bridge to decision (BTD) or a bridge to candidacy (BTC) treatment, in Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) levels 1 and 2 patients. However, it is possible that compared to patients with primary implantable-VADs (P-iVAD), the bridge-to-bridge (BTB) patients are more likely to develop complications. This retrospective study used data from 24 consecutive BTB patients who were initially implanted with Nipro p-VAD as BTD or BTC treatments between April 2011 and March 2016, and subsequently underwent conversion to an i-VAD. The data from 72 patients who underwent a primary i-VAD (P-iVAD) procedure were used for comparison. Between the two groups, there was no significant difference in the incidence of infectious events (p = 0.72) or stroke (p = 0.44). Orthotropic heart transplantation was performed in 6 of the 24 patients in the BTB group and in 21 of the 72 patients in the P-iVAD group. The 1- and 2-year survival rates were 95.8% and 95.8% in the BTB group and 91% and 85.8% in the P-iVAD group; these values were not significantly different between groups (p = 0.91). Based on these results we conclude that BTB using Nipro p-VAD is a reasonable strategy for treating patients with severe decompensated end-stage heart failure.

Assessment of Bleeding and Thrombosis Based on Aspirin Responsiveness after Continuous-Flow Left Ventricular Assist Device Placement.

PubMed

Floroff, Catherine K; Rieger, Krista L; Veasey, Tara M; Strout, Sara E; DeNino, Walter F; Meadows, Holly B; Stroud, Martha R; Toole, John M; Heyward, Dawn P; Brisco-Bacik, Meredith A; Cook, Jennifer L; Lazarchick, John; Uber, Walter E

Pump thrombosis (PT) is a severe complication of left ventricular assist device (LVAD) support. This study evaluated PT and bleeding after LVAD placement in patients responsive to a standard aspirin dose of 81 mg using platelet inhibition monitoring compared with initial nonresponders who were then titrated upward to achieve therapeutic response. Patients ≥ 18 years of age with initial placement of HeartMate II LVAD at our institution and at least one VerifyNow Aspirin test performed during initial hospitalization were included. The primary endpoints were bleeding and PT compared between initial aspirin responders and nonresponders. Of 85 patients, 19 (22%) were nonresponsive to initial aspirin therapy. Responders and nonresponders showed similar survival (p = 0.082), freedom from suspected/confirmed PT (p = 0.941), confirmed PT (p = 0.273), bleeding (p = 0.401), and incidence rates in PT and bleeding. Among the initial responders (<500 vs. 500-549 aspirin reaction units), there were no significant differences in survival (p = 0.177), freedom from suspected/confirmed PT (p = 0.542), confirmed PT (p = 0.159), bleeding (p = 0.879), and incidence of PT and bleeding. Platelet function testing may detect resistance to standard aspirin regimens used in LVAD patients. Dose escalation in initially nonresponsive patients to achieve responsiveness may confer a similar PT risk to patients initially responsive to standard aspirin dosing without increased bleeding risk.

Impact of mitral valve intervention with left ventricular assist device implantation on postoperative outcomes and morphologic change.

PubMed

Hata, Hiroki; Fujita, Tomoyuki; Ishibashi-Ueda, Hatsue; Kuroda, Kensuke; Seguchi, Osamu; Matsumoto, Yorihiko; Yanase, Masanobu; Sato, Takuma; Nakajima, Seiko; Fukushima, Norihide; Kobayashi, Junjiro

2018-06-01

Although mitral regurgitation (MR) is prevalent in patients with end-stage heart failure, the impact of mitral valve (MV) surgery on outcomes after left ventricular assist device (LVAD) implantation and morphologic changes of MV remains unclear. We retrospectively reviewed 74 patients who underwent LVAD implantation as a bridge to transplant. Of these, 11 (15%) underwent MV repair concomitant with or prior to LVAD implantation, while 27 patients with preoperative significant (moderate or greater) MR did not undergo concomitant MV surgery. The mean interval between LVAD implantation and the last echocardiographic examination was 913 days. Irrespective of MV surgery, significant LV reverse remodeling including decreased LV and left atrial dimension and improved MR severity was observed in all patients except for patients with prior MV surgery. Histopathological examination of explanted hearts removed at heart transplantation (n = 69) or autopsy (n = 5) revealed that the MV annulus was still dilated (mean perimeter 11.7 cm) in the patients with preoperative significant MR and no concomitant MV surgery. Concomitant MV surgery at the time of LVAD implantation for significant MR might not be always necessary for bridge to transplant or destination therapy cases. However, it might be required in patients having potential for cardiac recovery or patients with severe pulmonary hypertension and depressed right ventricle.

Large right ventricular sinusoids in an infant with aorta-left ventricular tunnel and proximal right coronary artery atresia.

PubMed

Chen, Peter C; Spinner, Joseph A; Heinle, Jeffrey S

2018-07-01

We report a 1-month-old infant diagnosed with an aorta-left ventricular tunnel, ventricular septal defect, and right coronary atresia with right ventricular sinusoids. The patient's anatomy and physiology did not indicate right-ventricular-dependent coronary circulation, and therefore right ventricular decompression could be performed without compromising coronary perfusion during surgical correction. A detailed understanding of the coronary anatomy is critical in managing this defect when coronary anomalies are present.

Cassini NASA Social

NASA Image and Video Library

2017-09-14

NASA Social attendees are seen during a science panel discussion with Cassini project scientist at JPL, Linda Spilker, Cassini interdisciplinary Titan scientist at Cornell University, Jonathan Lunine, Cassini Composite Infrared Spectrometer(CIRS) Instrument deputy principle investigator Connor Nixon, and Cassini assistant project science systems engineer Morgan Cable, Thursday, Sept. 14, 2017 at NASA's Jet Propulsion Laboratory in Pasadena, California. Since its arrival in 2004, the Cassini-Huygens mission has been a discovery machine, revolutionizing our knowledge of the Saturn system and captivating us with data and images never before obtained with such detail and clarity. On Sept. 15, 2017, operators will deliberately plunge the spacecraft into Saturn, as Cassini gathered science until the end. The “plunge” ensures Saturn’s moons will remain pristine for future exploration. During Cassini’s final days, mission team members from all around the world gathered at NASA’s Jet Propulsion Laboratory, Pasadena, California, to celebrate the achievements of this historic mission. Photo Credit: (NASA/Joel Kowsky)

Ablation of biglycan attenuates cardiac hypertrophy and fibrosis after left ventricular pressure overload.

PubMed

Beetz, Nadine; Rommel, Carolin; Schnick, Tilman; Neumann, Elena; Lother, Achim; Monroy-Ordonez, Elsa Beatriz; Zeeb, Martin; Preissl, Sebastian; Gilsbach, Ralf; Melchior-Becker, Ariane; Rylski, Bartosz; Stoll, Monika; Schaefer, Liliana; Beyersdorf, Friedhelm; Stiller, Brigitte; Hein, Lutz

2016-12-01

Biglycan, a small leucine-rich proteoglycan, has been shown to play an important role in stabilizing fibrotic scars after experimental myocardial infarction. However, the role of biglycan in the development and regression of cardiomyocyte hypertrophy and fibrosis during cardiac pressure overload and unloading remains elusive. Thus, the aim of the present study was to assess the effect of biglycan on cardiac remodeling in a mouse model of left ventricular pressure overload and unloading. Left ventricular pressure overload induced by transverse aortic constriction (TAC) in mice resulted in left ventricular dysfunction, fibrosis and increased biglycan expression. Fluorescence- and magnetic-assisted sorting of cardiac cell types revealed upregulation of biglycan in the fibroblast population, but not in cardiomyocytes, endothelial cells or leukocytes after TAC. Removal of the aortic constriction (rTAC) after short-term pressure overload (3weeks) improved cardiac contractility and reversed ventricular hypertrophy but not fibrosis in wild-type (WT) mice. Biglycan ablation (KO) enhanced functional recovery but did not resolve cardiac fibrosis. After long-term TAC for 9weeks, ablation of biglycan attenuated the development of cardiac hypertrophy and fibrosis. In vitro, biglycan induced hypertrophy of neonatal rat cardiomyocytes and led to activation of a hypertrophic gene program. Putative downstream mediators of biglycan signaling include Rcan1, Abra and Tnfrsf12a. These genes were concordantly induced by TAC in WT but not in biglycan KO mice. Left ventricular pressure overload induces biglycan expression in cardiac fibroblasts. Ablation of biglycan improves cardiac function and attenuates left ventricular hypertrophy and fibrosis after long-term pressure overload. In vitro biglycan induces hypertrophy of cardiomyocytes, suggesting that biglycan may act as a signaling molecule between cell types to modulate cardiac remodeling. Copyright © 2016 Elsevier Ltd. All rights

NASA CORE - A Worldwide Distribution Center for Educational Materials.

NASA Astrophysics Data System (ADS)

Kaiser-Holscott, K.

2005-05-01

The Lorain County Joint Vocational School District (JVS) administers NASA's Central Operation of Resources for Educators (CORE) for the purpose of: A. Operating a mail order service to supply educators around the world with NASA's educational materials; B. Servicing NASA Education Programs/Projects with NASA's educational materials; C. Supporting the NASA Educator Resource Center Network with technology resources for the next generation of ERC. D. Support NASA's mission to inspire the next generation of explorers...as only NASA can; E. Inspire and motivate students to pursue careers in geography, science, technology, engineering and mathematics. This is accomplished by the continued operation of a central site that educators can contact to obtain information about NASA educational programs and research; obtain NASA educational publications and media; and receive technical support for NASA multimedia materials. In addition CORE coordinates the efforts of the 67 NASA Educator Resource Centers to establish a more effective network to serve educators. CORE directly supports part of NASA's core mission, To Inspire the Next Generation of Explorers.as only NASA can. CORE inspires and motivates students to pursue careers in geography, science, technology, engineering and mathematics by providing educators with exciting and NASA-unique educational material to enhance the students' learning experience. CORE is located at the Lorain County Joint Vocational School (JVS) in Oberlin, Ohio. Students at the JVS assist with the daily operations of CORE. This assistance provides the students with valuable vocational training opportunities and helps the JVS reduce the amount of funding needed to operate CORE. CORE has vast experience in the dissemination of NASA educational materials as well as a network of NASA Education Resource Centers who distribute NASA materials to secondary and post-secondary schools and universities, informal educators, and other interested individuals and

Anchoring in Destination-Therapy Left Ventricular Assist Device Decision Making: A Mechanical Turk Survey.

PubMed

Paine, Arcadia M; Allen, Larry A; Thompson, Jocelyn S; McIlvennan, Colleen K; Jenkins, Amy; Hammes, Andrew; Kroehl, Miranda; Matlock, Daniel D

2016-11-01

People with end-stage heart failure may have to decide about destination-therapy left ventricular assist device (DT-LVAD). Individuals facing difficult decisions often rely on heuristics, such as anchoring, which predictably bias decision outcomes. We aimed to investigate whether showing a larger historical Heartmate XVE creates an anchoring effect, making the smaller Heartmate II (HMII) appear more favorable. With the use of Amazon Mechanical Turk, participants watched videos asking them to imagine themselves dying of end-stage heart failure, then were presented the option of LVAD as potentially life-prolonging therapy. Participants were randomized to a control group who were only shown the HMII device, and the intervention group who saw the XVE device before the HMII. Participants then completed surveys. A total of 487 participants completed the survey (control = 252; intervention = 235); 79% were <40 years of age, 84% were white, and 55% were male. The intervention group was not more likely to accept the LVAD therapy (68% vs 61%; P = .37). However, participants in the intervention group were more likely (51% vs 17%; P < .01) to agree or strongly agree with the statement that the HMII was "smaller than expected." Participants in the intervention group were also more likely to rate the size of the device as "important" or "very important" in their decision (61% vs 46%; P < .01). Although the XVE anchor did not affect likelihood of accepting the LVAD, it did affect device perception. This article highlights an important point with clinical implications: factors such as anchoring have the potential to inappropriately influence perceptions and decisions and should be carefully considered in research and practice. Copyright © 2016 Elsevier Inc. All rights reserved.

Outcomes in advanced heart failure patients with left ventricular assist devices for destination therapy.

PubMed

Park, Soon J; Milano, Carmelo A; Tatooles, Antone J; Rogers, Joseph G; Adamson, Robert M; Steidley, D Eric; Ewald, Gregory A; Sundareswaran, Kartik S; Farrar, David J; Slaughter, Mark S

2012-03-01

The HeartMate II (HMII) destination therapy (DT) trial demonstrated significant improvements in outcomes in continuous-flow left ventricular assist devices compared with patients implanted with the pulsatile-flow HeartMate XVE. The primary hypothesis of the current study is that trial patients enrolled after the initial data cohort would have better clinical outcomes. Two hundred eighty-one patients who underwent HMII for DT from May 2007 to March 2009 (Mid Trial [MT] group) were compared with the initial 133 HMII patients from March 2005 to May 2007 (Early Trial [ET] group). Patient entry criteria were the same during the 2 time periods. Survival, adverse events, and quality of life were compared between the 2 groups. Baseline characteristics were similar between the groups. Compared with the ET group, patients in the MT group had reduced adverse event rates for bleeding requiring transfusions (1.66 versus 1.13 events per patient-year, P<0.001), sepsis (0.38 versus 0.27, P=0.025), device-related infections (0.47 versus 0.27, P<0.001), and hemorrhagic stroke (0.07 versus 0.03, P=0.01). Other event rates were similar between groups including ischemic stroke (0.06 versus 0.05 events per patient-year, P=0.57). Survival at 1 year in the MT group was 73% versus 68% in the ET group (P=0.21). Additionally, there was a significant reduction in deaths caused by hemorrhagic stroke (P=0.01). Quality of life improvements were significant in both the groups (P<0.001). The benefit of DT therapy with the HMII is confirmed in subsequent trial patients, with improved adverse event rates and a strong trend for improvements in survival. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00121485.

Contemporary management of acute right ventricular failure: a statement from the Heart Failure Association and the Working Group on Pulmonary Circulation and Right Ventricular Function of the European Society of Cardiology.

PubMed

Harjola, Veli-Pekka; Mebazaa, Alexandre; Čelutkienė, Jelena; Bettex, Dominique; Bueno, Hector; Chioncel, Ovidiu; Crespo-Leiro, Maria G; Falk, Volkmar; Filippatos, Gerasimos; Gibbs, Simon; Leite-Moreira, Adelino; Lassus, Johan; Masip, Josep; Mueller, Christian; Mullens, Wilfried; Naeije, Robert; Nordegraaf, Anton Vonk; Parissis, John; Riley, Jillian P; Ristic, Arsen; Rosano, Giuseppe; Rudiger, Alain; Ruschitzka, Frank; Seferovic, Petar; Sztrymf, Benjamin; Vieillard-Baron, Antoine; Yilmaz, Mehmet Birhan; Konstantinides, Stavros

2016-03-01

Acute right ventricular (RV) failure is a complex clinical syndrome that results from many causes. Research efforts have disproportionately focused on the failing left ventricle, but recently the need has been recognized to achieve a more comprehensive understanding of RV anatomy, physiology, and pathophysiology, and of management approaches. Right ventricular mechanics and function are altered in the setting of either pressure overload or volume overload. Failure may also result from a primary reduction of myocardial contractility owing to ischaemia, cardiomyopathy, or arrhythmia. Dysfunction leads to impaired RV filling and increased right atrial pressures. As dysfunction progresses to overt RV failure, the RV chamber becomes more spherical and tricuspid regurgitation is aggravated, a cascade leading to increasing venous congestion. Ventricular interdependence results in impaired left ventricular filling, a decrease in left ventricular stroke volume, and ultimately low cardiac output and cardiogenic shock. Identification and treatment of the underlying cause of RV failure, such as acute pulmonary embolism, acute respiratory distress syndrome, acute decompensation of chronic pulmonary hypertension, RV infarction, or arrhythmia, is the primary management strategy. Judicious fluid management, use of inotropes and vasopressors, assist devices, and a strategy focusing on RV protection for mechanical ventilation if required all play a role in the clinical care of these patients. Future research should aim to address the remaining areas of uncertainty which result from the complexity of RV haemodynamics and lack of conclusive evidence regarding RV-specific treatment approaches. © 2016 The Authors European Journal of Heart Failure © 2016 European Society of Cardiology.

Location, variations, and predictors of epicardial fat mapping using multidetector computed tomography to assist epicardial ventricular tachycardia ablation.

PubMed

Sourwine, Mariaileen; Jeudy, Jean; Miller, Brian; Vunnam, Rama; Imanli, Hasan; Mesubi, Olurotimi; Etienne-Mesubi, Martine; See, Vincent; Shorofsky, Stephen; Dickfeld, Timm

2017-10-01

A significant number of ventricular tachycardia circuits are located close to the epicardial surface and are amendable to epicardial ablation. Epicardial fat often interferes with substrate mapping and ablation, though little is known regarding the distribution of fat and its fluctuation with the cardiac cycle. We studied 40 patients who underwent a 64-slice multidetector computed tomography in order to describe patterns of epicardial fat distribution, variation during cardiac cycle, and clinical predictors of epicardial fat. Multiplanar reconstructions were analyzed during systole and diastole in six cross-sections. Epicardial fat thickness was measured across multiple wall segments in each view. Epicardial fat was found to be thicker in areas overlying coronary vasculature (7.8 ± 2.6 mm vs 3.5 ± 0.9 mm, P = 0.001), along with the right ventricular wall (3.9 ± 0.8 mm vs 2.6 ± 0.6 mm, P = 0.001) and the ventricular base (6.1 ± 1.7 mm vs 4.6 ± 1.6 mm, P < 0.01). Epicardial fat thickness increased 27% during systole as compared to diastole (4.9 ± 2.7 mm vs 6.2 ± 3.0 mm, P = 0.04). Variation with cardiac cycle was most evident along the right ventricular wall (3.9 ± 0.8 mm vs 5.0 ± 1.3 mm, P = 0.001) and nonvascular areas (P = 0.001), especially at the ventricular base (3.7 ± 1.1 mm vs 5.3 ± 1.5 mm, P = 0.001). In multivariate logistic regression, we found that age >50 years (P = 0.031) and coronary artery disease (P = 0.023) were statistically correlated with epicardial fat >5-mm thickness and body mass index > 33 (P = 0.052) nearly so. Baseline epicardial fat thickness >5 mm is common in areas typically targeted during epicardial ablation and further increases during the cardiac cycle. Simple clinical characteristics can identify patients with >5 mm epicardial fat in which preprocedural computed tomography imaging and three-dimensional fat map reconstruction may facilitate epicardial ablation. © 2017 Wiley Periodicals

Dynamic Changes of QRS Morphology of Premature Ventricular Contractions During Ablation in the Right Ventricular Outflow Tract: A Case Report.

PubMed

Yue-Chun, Li; Jia-Feng, Lin; Jia-Xuan, Lin

2015-10-01

Electrocardiographic characteristics can be useful in differentiating between right ventricular outflow tract (RVOT) and aortic sinus cusp (ASC) ventricular arrhythmias. Ventricular arrhythmias originating from ASC, however, show preferential conduction to RVOT that may render the algorithms of electrocardiographic characteristics less reliable. Even though there are few reports describing ventricular arrhythmias with ASC origins and endocardial breakout sites of RVOT, progressive dynamic changes in QRS morphology of the ventricular arrhythmias during ablation obtained were rare.This case report describes a patient with symptomatic premature ventricular contractions of left ASC origin presenting an electrocardiogram (ECG) characteristic of right ventricular outflow tract before ablation. Pacing at right ventricular outflow tract reproduced an excellent pace map. When radiofrequency catheter ablation was applied to the right ventricular outflow tract, the QRS morphology of premature ventricular contractions progressively changed from ECG characteristics of right ventricular outflow tract origin to ECG characteristics of left ASC origin.Successful radiofrequency catheter ablation was achieved at the site of the earliest ventricular activation in the left ASC. The distance between the successful ablation site of the left ASC and the site with an excellent pace map of the RVOT was 20 mm.The ndings could be strong evidence for a preferential conduction via the myocardial bers from the ASC origin to the breakout site in the right ventricular outflow tract. This case demonstrates that ventricular arrhythmias with a single origin and exit shift may exhibit QRS morphology changes.

NASA's Software Bank (CLIPS)

NASA Technical Reports Server (NTRS)

1991-01-01

C Language Integrated Production System (CLIPS) is a NASA Johnson Space Center developed software shell for developing expert systems, is used by researchers at Ohio State University to determine solid waste disposal sites to assist in historic preservation. The program has various other applications and has even been included in a widely-used textbook.

Biomedical applications of NASA technology

NASA Technical Reports Server (NTRS)

Friedman, Donald S.

1991-01-01

Through the active transfer of technology, NASA Technology Utilization (TU) Program assists private companies, associations, and government agencies to make effective use of NASA's technological resources to improve U.S. economic competitiveness and to provide societal benefit. Aerospace technology from such areas as digital image processing, space medicine and biology, microelectronics, optics, and electro-optics, and ultrasonic imaging have found many secondary applications in medicine. Examples of technology spinoffs are briefly discussed to illustrate the benefits realized through adaptation of aerospace technology to solve health care problems. Successful implementation of new technologies increasingly requires the collaboration of industry, universities, and government and the TU Program serves as the liaison to establish such collaborations with NASA. NASA technology is an important resource to support the development of new medical products and techniques that will further advance the quality of health care available in the U.S. and worldwide.

Summary of NASA Aerospace Flight Battery Systems Program activities

NASA Technical Reports Server (NTRS)

Manzo, Michelle; Odonnell, Patricia

1994-01-01

A summary of NASA Aerospace Flight Battery Systems Program Activities is presented. The NASA Aerospace Flight Battery Systems Program represents a unified NASA wide effort with the overall objective of providing NASA with the policy and posture which will increase the safety, performance, and reliability of space power systems. The specific objectives of the program are to: enhance cell/battery safety and reliability; maintain current battery technology; increase fundamental understanding of primary and secondary cells; provide a means to bring forth advanced technology for flight use; assist flight programs in minimizing battery technology related flight risks; and ensure that safe, reliable batteries are available for NASA's future missions.

Continuous-flow left ventricular assist device therapy in patients with preoperative hepatic failure: are we pushing the limits too far?

PubMed

Weymann, Alexander; Patil, Nikhil P; Sabashnikov, Anton; Mohite, Phrashant N; Garcia Saez, Diana; Bireta, Christian; Wahlers, Thorsten; Karck, Matthias; Kallenbach, Klaus; Ruhparwar, Arjang; Fatullayev, Javid; Amrani, Mohamed; De Robertis, Fabio; Bahrami, Toufan; Popov, Aron-Frederik; Simon, Andre R

2015-04-01

The purpose of this study was to evaluate the effects and outcome of continuous-flow left ventricular assist device (cf-LVAD) therapy in patients with preoperative acute hepatic failure. The study design was a retrospective review of prospectively collected data. Included were 42 patients who underwent cf-LVAD implantation (64.3% HeartMate II, 35.7% HeartWare) between July 2007 and May 2013 with preoperative hepatic failure defined as elevation of greater than or equal to two liver function parameters above twice the upper normal range. Mean patient age was 35 ± 12.5 years, comprising 23.8% females. Dilated cardiomyopathy was present in 92.9% of patients (left ventricular ejection fraction 17.3 ± 5.9%). Mean support duration was 511 ± 512 days (range: 2-1996 days). Mean preoperative laboratory parameters for blood urea nitrogen, serum creatinine, total bilirubin, and alanine aminotransferase were 9.5 ± 5.4 mg/dL, 110.3 ± 42.8 μmol/L, 51.7 ± 38.3 mmol/L, and 242.1 ± 268.6 U/L, respectively. All parameters decreased significantly 1 month postoperatively. The mean preoperative modified Model for Endstage Liver Disease excluding international normalized ratio score was 16.03 ± 5.57, which improved significantly after cf-LVAD implantation to 10.62 ± 5.66 (P < 0.001) at 7 days and 5.83 ± 4.98 (P < 0.001) at 30 days postoperatively. One-year and 5-year survival was 75.9 and 48.1%, respectively. 21.4% of the patients underwent LVAD explantation for myocardial recovery, 16.7% were successfully transplanted, and 7.1% underwent LVAD exchange for device failure over the follow-up period. Patients with preexisting acute hepatic failure are reasonable candidates for cf-LVAD implantation, with excellent rates of recovery and survival, suggesting that cf-LVAD therapy should not be denied to patients merely on grounds of "preoperative elevated liver enzymes/hepatopathy." Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley

Malignant ventricular arrhythmias in alcoholic cardiomyopathy.

PubMed

Guzzo-Merello, Gonzalo; Dominguez, Fernando; González-López, Esther; Cobo-Marcos, Marta; Gomez-Bueno, Manuel; Fernandez-Lozano, Ignacio; Millan, Isabel; Segovia, Javier; Alonso-Pulpon, Luis; Garcia-Pavia, Pablo

2015-11-15

Excessive alcohol consumption is a well-known aetiology of atrial arrhythmias but there is little information concerning the prevalence or incidence of malignant ventricular arrhythmias in alcoholic cardiomyopathy (ACM). This study sought to investigate incidence and predictive factors of ventricular arrhythmias in ACM. Retrospective observational study of the clinical characteristics and long-term arrhythmic events in 282 consecutive patients with ACM (94 individuals) and idiopathic dilated cardiomyopathy (IDCM) (188 individuals) evaluated between 1993 and 2011. During a median follow-up of 38months (IQR:12-77), 42 patients died and 79 underwent heart transplantation [31 (33%) with ACM vs 90 (48%) with IDCM; p=0.017]. A total of 37 (13%) patients [18 (19%) ACM vs 20 (11%) IDCM; p=0.048] suffered malignant ventricular arrhythmias. On multivariate analysis, left bundle branch block (LBBB) (OR 2.4; CI95%: 1.2-5; p=0.015) and alcoholic aetiology (OR 2.3; CI95%: 1.1-4.5; p=0.026) were the only independent predictors of malignant ventricular arrhythmic events. A total of 18 (19%) ACM patients experienced 20 malignant ventricular arrhythmic events (4 aborted SCD, 8 SCD and 8 appropriate ICD therapies). At baseline evaluation, the only independent predictor of malignant ventricular arrhythmias in ACM patients was LBBB (OR 11.2; CI95%: 2.6-50; p=0.001). No malignant ventricular arrhythmias were recorded during follow-up in ACM patients if left ventricular ejection fraction (LVEF) had increased or remained ≥40%. Malignant ventricular arrhythmias are more frequent in ACM than in IDCM. LBBB identifies ACM patients with increased risk of SCD. No malignant ventricular arrhythmias were found during follow-up in ACM patients when LVEF was ≥40%. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Ventricular ectopy in patients with left ventricular dysfunction: should it be treated?

PubMed

Chen, Taibo; Koene, Ryan; Benditt, David G; Lü, Fei

2013-01-01

Ventricular premature complexes (VPCs) are commonly encountered in patients with congestive heart failure (CHF). Frequent ventricular ectopy can be associated with deterioration of cardiac function and may lead to VPC-induced cardiomyopathy. VPC-induced inter- and/or intraventricular dyssynchrony has been postulated as the main mechanism underlying VPC-induced left ventricular dysfunction. For risk stratification, VPCs in the setting of CHF can not be regarded to be a benign arrhythmia as in an apparently healthy subject. However, any potential survival benefits to be derived from suppression of VPCs or nonsustained ventricular tachycardia in CHF may be offset by the negative inotropic and proarrhythmic effects of antiarrhythmic drugs and may be masked by the risk of death that is already high in this subgroup of patients. β-Blockers are currently considered to be the first-line therapy, with amiodarone as a back-up. Catheter ablation, although invasive and not without procedural risk, avoids the common adverse effects of currently available antiarrhythmic medications. From a standpoint of preventing or reversing left ventricular dysfunction, frequent VPCs should be treated earlier regardless of their site of origin or the presence of associated symptoms, such as palpitations. Catheter ablation may be the preferable approach in selected patients, particularly when β-blocker therapy has been ineffective or not tolerated. Copyright © 2013 Elsevier Inc. All rights reserved.

Nursing care of the ambulatory patient with a mechanical assist device.

PubMed

Reedy, J E; Ruzevich, S A; Noedel, N R; Vitale, L J; Merkle, E J

1990-01-01

Since 1986, 10 men and one woman were ambulatory while supported with mechanical assist devices as a bridge to heart transplantation. Four patients received a subclavian intraaortic balloon pump, two were supported with a Novacor left ventricular assist system, three patients received Pierce-Donachy ventricular assist devices, and one patient received a Jarvik 7 total artificial heart. One patient with an intraaortic balloon pump later received a left ventricular assist system because of hemodynamic deterioration despite the intraaortic balloon pump. Before device insertion all 11 patients were in cardiogenic shock despite inotropic and vasodilator support. The time of support ranged from 8 to 440 days (median, 24 days). In-house coverage by the circulatory support team was necessary only during the first 24 to 72 hours of support. When the patient's condition was stabilized, nursing staff monitored the devices with "on-call" availability of the circulatory support team. After implant of the device, all patients were able to perform activities of daily living. Once patients were able to walk in their hospital rooms, ambulation began in the hallways; frequency and distance were gradually increased. Four of the patients walked outside the hospital while tethered to the drive console. Daily physical therapy contributed to increased exercise tolerance. Protective isolation was used before and after transplantation to minimize the risk of infection. Sterile dressing changes (gown, gloves, mask) were applied to drive lines, cannula sites, and incisions. All invasive lines and catheters were removed as soon as the patient's clinical condition warranted, and noninvasive monitoring was used to decrease the chance of infection.(ABSTRACT TRUNCATED AT 250 WORDS)

NASA Tech Briefs, Spring 1977. Volume 2, No. 1

NASA Technical Reports Server (NTRS)

1977-01-01

Topics: NASA TU Services: Technology Utilization services that can assist you in learning about and applying NASA technology; New Product Ideas: A summary of selted innovations of value to manufacturers for the development of new products; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Life Sciences; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences.

NASA Tech Briefs, Summer 1977. Volume 2, No. 2

NASA Technical Reports Server (NTRS)

1977-01-01

Topics: NASA TU Services: Technology Utilization services that can assist you in learning about and applying NASA technology; New Product Ideas: A summary of selected Innovations of value to manufacturers for the development of new products; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Life Sciences; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences.

Friends of the National Library of Medicine | NIH MedlinePlus the Magazine

MedlinePlus

... Dr. DeBakey was also given by Dr. Ronald Cotton, a graduate of the DeBakey High School for ... medicine, health care, and or the sciences. Dr. Cotton discussed his receipt of his medical degree from ...

Early Feasibility Testing and Engineering Development of a Sutureless Beating Heart (SBH) Connector for Left Ventricular Assist Devices (LVAD)

PubMed Central

Koenig, Steven C; Jimenez, Jorge H; West, Seth D; Sobieski, Michael A; Choi, Young; Monreal, Gretel; Giridharan, Guruprasad A; Soucy, Kevin G; Slaughter, Mark S

2014-01-01

APK Advanced Medical Technologies (Atlanta, GA) is developing a sutureless beating heart (SBH) left ventricular assist device (LVAD) connector system consisting of anchoring titanium coil, titanium cannula with integrated silicone hemostatic valve, coring and delivery tool, and LVAD locking mechanism to facilitate LVAD inflow surgical procedures. Feasibility testing was completed in human cadavers (n=4) under simulated normal and hypertensive conditions using saline to observe seal quality in degraded human tissue and assess anatomic fit; acutely in ischemic heart failure (IHF) bovine model (n=2) to investigate short-term performance and ease of use; and chronically for 30-days in healthy calves (n=2) implanted with HeartWare HVAD to evaluate performance and biocompatibility. Complete hemostasis was achieved in human cadavers and animals at LV pressures up to 170 mmHg. In animals, off pump (no cardiopulmonary bypass) anchoring of the connector was accomplished in less than 1 minute with no residual bleeding after full delivery and locking of the LVAD; and implant of connector and LVAD were successfully completed in under 10 minutes with total procedure blood loss less than 100mL. In chronic animals prior to necropsy, no signs of leakage or disruption at the attachment site were observed at systolic LV pressures >200 mmHg. PMID:25238500

NASA-STD 3001 and the Human Integration Design Handbook (HIDH): Evolution of NASA-STD-3000

NASA Technical Reports Server (NTRS)

Pickett, Lynn; Connolly, Janis; Arch, M.; Tillman, Barry; Russo, Dane

2007-01-01

The Habitability & Environmental Factors and Space Medicine Divisions have developed the Space Flight Human System Standard (SFHSS) (NASA-STD-3001) to replace NASA-STD-3000 as a new NASA standard for all human spaceflight programs. The SFHSS is composed of 2 volumes. Volume 1, Crew Health, contains medical levels of care, permissible exposure limits, and fitness for duty criteria, and permissible outcome limits as a means of defining successful operating criteria for the human system. Volume 2, Habitability and Environmental Health, contains environmental, habitability and human factors standards. Development of the Human Integration Design Handbook (HIDH), a companion to the standard, is currently under construction and entails the update and revision of NASA-STD-3000 data. This new handbook will, in the fashion of NASA STD-3000, assist engineers and designers in appropriately applying habitability, environmental and human factors principles to spacecraft design. Organized in a chapter-module-element structure, the HIDH will provide the guidance for the development of requirements, design considerations, lessons learned, example solutions, background research, and assist in the identification of gaps and research needs in the disciplines. Subject matter experts have been and continue to be solicited to participate in the update of the chapters. The purpose is to build the HIDH with the best and latest data, and provide a broad representation from experts in industry, academia, the military and the space program. The handbook and the two standards volumes work together in a unique way to achieve the required level of human-system interface. All new NASA programs will be required to meet Volumes 1 and 2. Volume 2 presents human interface goals in broad, non-verifiable standards. Volume 2 also requires that each new development program prepare a set of program-specific human factors requirements. These program-specific human and environmental factors requirements

NASA USRP Internship Final Report

NASA Technical Reports Server (NTRS)

Black, Jesse A.

2010-01-01

The purpose of this report is to describe the body of work I have produced as a NASA USRP intern in the spring 2010. My mentor during this time was Richard Birr and I assisted him with many tasks in the advanced systems group in the engineering design lab at NASA's Kennedy space center. The main priority was and scenario modeling for the FAA's next generation air traffic control system and also developing next generation range systems for implementation at Kennedy space center. Also of importance was the development of wiring diagrams for the portable communications terminal for the desert rats program.

NASA Bioreactor Demonstration System

NASA Technical Reports Server (NTRS)

2002-01-01

Leland W. K. Chung (left), Director, Molecular Urology Therapeutics Program at the Winship Cancer Institute at Emory University, is principal investigator for the NASA bioreactor demonstration system (BDS-05). With him is Dr. Jun Shu, an assistant professor of Orthopedics Surgery from Kuming Medical University China. The NASA Bioreactor provides a low turbulence culture environment which promotes the formation of large, three-dimensional cell clusters. Due to their high level of cellular organization and specialization, samples constructed in the bioreactor more closely resemble the original tumor or tissue found in the body. The Bioreactor is rotated to provide gentle mixing of fresh and spent nutrient without inducing shear forces that would damage the cells. The work is sponsored by NASA's Office of Biological and Physical Research. The bioreactor is managed by the Biotechnology Cell Science Program at NASA's Johnson Space Center (JSC). NASA-sponsored bioreactor research has been instrumental in helping scientists to better understand normal and cancerous tissue development. In cooperation with the medical community, the bioreactor design is being used to prepare better models of human colon, prostate, breast and ovarian tumors. Cartilage, bone marrow, heart muscle, skeletal muscle, pancreatic islet cells, liver and kidney are just a few of the normal tissues being cultured in rotating bioreactors by investigators. Credit: Emory University.