introduction march . april 200474

Myocardial Recovery After Chronic Mechanical Assist Device Support: Fact or Fiction?

Mark Slaughter, MD, Guest EditorFrom the Mechanical Assist Device Program, Department of Cardiothoracic Surgery, Advocate Christ Medical Center, Oak Lawn, ILAddress for correspondence: Mark Slaughter, MD, Mechanical Assist Device Program, Department of Cardiothoracic Surgery, Advocate Christ Medical Center, 4400 West 95th Street, Suite 205, Oak Lawn, IL 60453E-mail: mscabg@aol.com

Cardiac transplantation is still con-sidered the final treatment option

for patients with end-stage congestive heart failure (CHF). Unfortunately, car-diac transplantation is limited by the number of available donors and can-not meet the needs of all patients with severe CHF. In this issue of Congestive Heart Failure, Frazier and Delgado (p. 109) make a significant contribution by identifying and clinically defining patients who benefit from mechanical assist device support resulting in myo-cardial recovery. Previously, most reports of myocardial recovery after mechanical assist device support were anecdotal and isolated cases. For example, Farrar et al.1 reported a series of 22 patients from 14 medical centers with good long-term outcome from myocardial recovery after mechanical assist device support. However, the majority of these patients had either myocarditis or postpartum cardiomyopathies as the underlying eti-ology. Frazier and Delgado now clearly show that patients with nonischemic and nonmyocarditis heart failure also can recover enough cardiac function to successfully undergo device removal.

Many questions remain regarding myocardial recovery after mechanical assist device support. It is now well established that chronic left ventricu-lar unloading with mechanical assist device support results in improvement in myocyte histology, decrease in myo-

cardial cytokines, decrease in neuro-hormonal activity, up-regulation in B-receptor density, and normalization of calcium transport of the sarcoplas-mic reticulum. However, these chang-es do not automatically mean that any given patient has enough clinical improvement in left ventricular func-tion to allow successful device removal. Mancini et al.2 reported that in their experience <10% of patients demon-strated sufficient clinical recovery of left ventricular function to undergo device explantation. Bruckner et al.3 recently reported that the degree of fibrosis and myocyte size at the time of device implantation may predict myocardial improvement during left ventricular assist device support.

Which device to implant and how to wean patients off the device are also questions that remain unclear. In their report, Frazier and Delgado report successful recovery in three patients implanted with a Thoratec (Pleasanton, CA) paracorporeal ven-tricular assist device (VAD). Connelly et al.4 recently demonstrated that a significant number of patients sup-ported with the HeartMate (Thoratec Corp, Pleasanton, CA) VAD experi-enced fusion of the native aortic leaf-lets. Therefore the HeartMate VAD, which is very successful as a bridge to transplantation and now for desti-nation therapy, may not be the best

choice for myocardial recovery and subsequent removal. Determinations of how to best reload the left ventricle and determine its suitability to take over for the VAD varies from center to center. Frazier and Delgado outline in detail their method of weaning using dobutamine and intermittent hand pumping. My colleagues and I5 previously reported our preference for limiting the stroke volume of the VAD over a period of days with a clinical assessment of exercise capacity at the end of weaning. Regardless of the method of weaning used, additional measurements or predictors of long-term function once the VAD has been removed are needed.

It is becoming more evident that myocardial recovery after chronic mechanical unloading for severe CHF is a clinical reality. Identifying which patients will benefit, which device to implant, which adjuvant medical thera-pies to employ, how long the duration of support should be, and how best to reload the ventricle or wean the patient from the device are issues that remain unanswered. With the continued experi-ence of Frazier and Delgado and others, we may someday understand all these issues and be able to confidently offer certain patients the option of VADs as a bridge to recovery and an alternative to transplantation, or at least to delay the need for cardiac transplantation.

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I N T R O D U C T I O N

Congestive Heart Failure (ISSN 1527-5299) is published bimonthly (Feb., April, June, Aug., Oct., Dec.) by CHF, Inc., Three Parklands Drive, Darien, CT 06820-3652. Copyright ©2004 by CHF, Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publishers. The opinions and ideas expressed in Congestive Heart Failure do not necessarily reflect those of the Editor and Publisher. For copies in excess of 25 or for commercial purposes, please contact Sarah Howell at showell@lejacq.com or 203.656.1711 x106.

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REFERENCES 1 Farrar DJ, Holman WR, McBride LR, et al. Long-term follow-up of Thoratec

ventricular assist device bridge-to-recovery patients successfully removed from support after recovery of ventricular function. J Heart Lung Transplant. 2002;21(5):516–521.

2 Mancini DM, Beniaminovitz A, Levin H, et al. Low incidence of myocar-dial recovery after left ventricular assist device implantation in patients with chronic heart failure. Circulation. 1998;98:2383–2389.

3 Bruckner BA, Razeghi P, Stetson S, et al. Degree of cardiac fibrosis and hypertrophy at time of implantation predicts myocardial improvement during left ventricular assist device support. J Heart Lung Transplant. 2004;23(1):36–42.

4 Connelly JH, Abrams J, Klima T, et al. Acquired commissural fusion of aortic valves in patients with left ventricular assist devices. J Heart Lung Transplant. 2003;22(12):1291–1295.

5 Slaughter MS, Silver MA, Farrar DJ, et al. A new method of monitoring recovery and weaning the Thoratec left ventricular assist device. Ann Thorac Surg. 2001;71:215–218.

Congestive Heart Failure (ISSN 1527-5299) is published bimonthly (Feb., April, June, Aug., Oct., Dec.) by CHF, Inc., Three Parklands Drive, Darien, CT 06820-3652. Copyright ©2004 by CHF, Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publishers. The opinions and ideas expressed in Congestive Heart Failure do not necessarily reflect those of the Editor and Publisher. For copies in excess of 25 or for commercial purposes, please contact Sarah Howell at showell@lejacq.com or 203.656.1711 x106.