Reversal of Myocyte Hypertrophy by Ventricular Unloading: Cardiac Improvement Without Adrenergic Receptor Upregulation and Relocalization

Pippa M. Schnee, BA; Naeema Shah, MS; Marianne Bergheim, BA; Brian J. Poindexter, MS; L. Max Buja, MD; Timothy J. Myers, BS; Branislav Radovancevic, MD; O. Howard Frazier, MD; Roger J. Bick, PhD

Disclosures

May 16, 2006

Abstract

In previous studies, we found that the improved contractile ability of cardiac myocytes from patients who have had left ventricular assist device (LVAD) support was due to a number of beneficial changes, most notably in calcium handling (increased sarcoplasmic reticulum calcium binding and uptake), improved integrity of cell membranes due to phospholipid reconstruction (reduced lysophospholipid content), and an upregulation of adrenoreceptors (increased adrenoreceptor numbers). However, in the case presented here, there was no increase in adrenoreceptor number, which is something that we usually find in core tissue at the time of LVAD removal or organ transplantation; also, there was no homogeneous postassist device receptor distribution. However, the patient was well maintained for 10 months following LVAD implantation, until a donor organ was available, regardless of the lack of adrenoreceptor improvement.

We conclude from these studies that cardiac recovery is the result of the initiation of multiple repair mechanisms, and that the lack of expected changes, in this case increased adrenoreceptors, is not always an accurate indicator of anticipated outcome. We suggest that interventions and strategies have to consider multiple, beneficial changes due to unloading and target a number of biochemical and structural areas to produce improvement, even if not all of these improvements occur.

Readers are encouraged to respond to George Lundberg, MD, Editor of MedGenMed, for the editor's eye only or for possible publication via email: glundberg@medscape.net

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Cite this: Reversal of Myocyte Hypertrophy by Ventricular Unloading: Cardiac Improvement Without Adrenergic Receptor Upregulation and Relocalization - Medscape - May 16, 2006.

Authors and Disclosures

Pippa M. Schnee, BA, Imaging and Microscopy Research Scientist (currently first-year medical student), Department of Pathology, University of Texas Medical School at Houston

Naeema Shah, MS, Cardiovascular Pathology and Transplant Research Assistant, Texas Heart Institute, Houston, Texas

Marianne Bergheim, BA, Cardiovascular Pathology and Transplant Research Assistant, Texas Heart Institute, Houston, Texas (currently first-year medical student at University of Texas Medical School at Houston)

Brian J. Poindexter, MS, Research Associate; Imaging Core Facility Supervisor, University of Texas Medical School at Houston

L. Max Buja, MD, Vice President for Academic Affairs, Professor of Pathology, University of Texas Medical School at Houston; Chief, Cardiovascular Pathology, Texas Heart Institute, Houston, Texas

Timothy J. Myers, BS, Supervisor, Cardiovascular Surgery and Transplant Research Pathology, Texas Heart Institute, Houston, Texas

Branislav Radovancevic, MD, Associate Director, Cardiovascular Surgery and Transplant Research, Texas Heart Institute, Houston, Texas; Clinical Associate Professor of Surgery, University of Texas Health Science Center at Houston

O. Howard Frazier, MD, Chief of Cardiovascular Transplantation; Director of Surgical Research, Texas Heart Institute, Houston, Texas

Roger J. Bick, PhD, Associate Professor of Pathology; Director of Imaging Core Facility, Department of Pathology, University of Texas Medical School at Houston. Email: roger.j.bick@uth.tmc.edu

Disclosure: Pippa M. Schnee, BA, has disclosed no relevant financial relationships.

Disclosure: Naeema Shah, MS, has disclosed no relevant financial relationships.

Disclosure: Marianne Bergheim, BA, has disclosed no relevant financial relationships.

Disclosure: Brian J. Poindexter, MS, has disclosed no relevant financial relationships.

Disclosure: L. Max Buja, MD, has disclosed no relevant financial relationships.

Disclosure: Timothy J. Myers, BS, has disclosed no relevant financial relationships.

Disclosure: Branislav Radovancevic, MD, has disclosed no relevant financial relationships.

Disclosure: O. Howard Frazier, MD, has disclosed no relevant financial relationships.

Disclosure: Roger J. Bick, PhD, has disclosed no relevant financial relationships.

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