E. Stanford

Biventricular Assist Device Utilization for Patients with Morbid Congestive Heart Failure A Justifiable Strategy

Background—The rationale for the use of a biventricular assist device (BiVAD) for morbid congestive heart failure (MCHF) has been questioned because of historically unacceptable rates of postimplant and post-transplant mortality as well as perceived barriers to their outpatient management. Methods and Results—All patients who received a Thoratec BiVAD from January 1990 to December 2003 at the University of Pittsburgh were studied retrospectively. There were a total of 73 patients (32% ischemic, 21% idiopathic, and 47% other) who had a BiVAD implanted. Before implantation, 100% were on ≥1 inotropic agent, and 77% had an intra-aortic balloon pump. Overall survival was 69%; 42 patients (84%) received cardiac transplantation, 5 patients (10%) were weaned, and 3 (6%) remained supported on BiVAD. If the 14 patients with postcardiotomy failure and acute myocardial infarction with shock are excluded, the overall survival improves to 75%. Five-year actuarial survival after heart transplantation was 58%. Of the 29 patients implanted before 2000, the 4-month actuarial freedom from driveline infections, bloodstream infections, and neurological events was 10%, 54%, and 48%, respectively, whereas the rates of these events for the 44 patients implanted after 2000 improved to 70%, 79%, and 80%, respectively. Since 2000, 21 (48%) patients were discharged from the hospital, of whom 38% went to an outpatient residence, 33% to a skilled nursing facility, and 29% to home. Once discharged, ≥1 readmission occurred in 45% and ≥2 readmissions in 48%. Conclusions—BiVAD support for MCHF has an acceptable overall mortality and survival to transplantation. Morbidity has been significantly reduced in the past 4 years, and management as an outpatient is achievable.

DOES A ROTARY PUMP PROVIDE FULL CARDIAC DECOMPRESSION AND CIRCULATORY SUPPORT? -FROM CLINICAL EXPERIENCES OF HEARTMATE II WITH SEVERE CONGESTIVE HEART FAILURE PATIENTS-

AND CIRCULATORY SUPPORT? -FROM CLINICAL EXPERIENCES OF HEARTMATE II WITH SEVERE CONGESTIVE HEART FAILURE PATIENTSHiroyuki Tsukui, Steve Winowich, Eileen Stanford, Jeffrey J Teuteberg, Robert L Kormos. Cardiothoracic Surgery, University of Pittsburgh, Pittsburgh, PA; Cardiology, University of Pittsburgh, Pittsburgh, PA. Purpose: Rotary pumps such as the Heartmate II left ventricular assist device (LVAD) (Thoratec Corporation, Pleasanton, CA) are small, nonpulsatile pumps designed for long-term use. However, its capability for providing full cardiac decompression and circulatory support has been questioned and indeed some have felt that the only safe way rotary pumps can be used is in an assistive mode. Methods: Three patients (Ischemic cardiomyopathy: 2, Post-partum cardiomyopathy: 1, ejection fraction: 10–20%) implanted the HeartMate II LVAD were followed using regular transthoracic echocardiography (TTE). Pump rpm, aortic valve opening (AVO), and left ventricular end-diastolic diameter (LVDd) were measured while changing pump rpm. Results: Full cardiac decompression and circulatory support were observed in all three patients. With the increasing of pump rpm, LVDd and the frequency of AVO decreased in inverse proportion. At an appropriate pump rpm setting, the aortic valve closed completely and LVDd decreased to 60–70% of preoperative LVDd without causing suction by the apical cannula. Longterm renal and circulatory function was normal without heart failure symptoms. Considerations: The Heartmate II provides sufficient circulatory support at an appropriate pump rpm setting in patients with severe congestive heart failure. Long-term full circulatory support can be achieved which is a requirement for destination therapy. INITIAL RESULTS WITH THE PEDIATRIC JARVIK 2000 HEART Robert Jarvik, Bartley Griffith, Greg Burgreen, Michael Morrow, Andrew Lewis. Research, Jarvik Heart, Inc., New York, NY; U of Maryland, Baltimore, MD; Mississippi State U, Starkville, MS. Under the NIH program to develop pediatric mechanical circulatory support systems, we have completed design, fabrication, and initial bench testing of the child model pump, an intraventricular axial flow pump connected from apex to aorta like the adult model Jarvik 2000. The device is one third the size and weight of the adult pump. Parameters include: Adult Jarvik 2000: 26 mm diameter x 7.5 cm long, 30cc, 90g, 16 mm diameter aortic graft, 8–12,000 RPM, 1–6 L/min. Pediatric Jarvik 2000: 17.8 mm diameter x 5.5 cm long, 10cc, 35g, 10mm diameter aortic graft, 10–14,000 RPM, 0.5–5 L/min. Computational fluid dynamics run on the initial prototype blade design predicted excellent flow pressure performance and very good pressure recovery by the stators which has been confirmed In Vitro, as shown below. Negligible losses were predicted by CFD at the pump outflow and graft. Modification of the leading edge of the impeller based on the CFD results was made to avoid local cavitation. Other blade design iterations are planned based on the In Vivo findings. Implants in small sheep will begin in February 2005. The system initially utilizes the same controller as the adult model while a smaller controller and battery system are developed.

Using non-invasive quantitative echocardiography during weaning trials to assess left ventricular recovery on mechanical assist devices

compare pulsatile and nonpulsatile flow generated by LVADs with outflow to the ascending aorta and descending aorta. Methods: An in vitro mock circulatory loop, driven by either a pulsatile or a nonpulsatile LVAD was anastomosed to transparent aortic models at either ascending or descending aortic position. The aortic valve was kept closed modeling no native cardiac output. Normal saline was used as a blood substitute. Methylene blue dye was injected to illustrate flow patterns in the ascending aorta and aortic arch. Dye washout time was used as a marker of flow stagnation and potential thrombogenicity. Cardiac output, afterload and coronary flow were measured. Results: Dye washout times for 5 L/min flow rate were 2.0 0.8, 2.0 0.7, 5.0 0.8, and 8.0 4.4 sec for pulsatile ascending (PA), continuous ascending (CA), pulsatile descending (PD), and continuous descending (CD), respectively. Coronary flow was 265, 312, 310, and 286 ml/min for PA, CA, PD, and CD, respectively. Dye washout times for 4 L/min flow rate were 3.0 1.0, 3.0 0.8, 14.0 3.8, and 25.0 9.1 sec for PA, CA, PD, and CD, respectively. Coronary flow was 210, 240, 225, and 233 ml/min for PA, CA, PD, and CD, respectively. Conclusion: LVAD descending aortic anastomosis and retrograde aortic flow is associated with significantly increased (P 0.001) flow stagnation in the ascending aorta. This may increase the risk for thromboembolism in patients solely relying on retrograde aortic flow. There were no differences in coronary flow across the study groups.