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Ann Thorac Surg 2000;69:1863-1864
© 2000 The Society of Thoracic Surgeons
a Department of Cardiovascular-Thoracic Surgery, Rush-Presbyterian-St. Luke’s Medical Center, 1725 West Harrison St, Suite 1156, Chicago, IL 60612, USA
e-mail: verdi_disesa{at}rush.edu
Elefteriades and colleagues report the experimental development of a heart transplant technique that preserves the recipient right ventricle (RV). In a canine model, the investigators demonstrate the feasibility of cardiectomy restricted to the left ventricle (LV) with subsequent transplantation resulting in a circulation characterized by two right ventricles connected in parallel. The authors conclude that this technique may be useful for situations in which recipient pulmonary hypertension increases the risk of early donor right heart failure.
This is an original and potentially useful idea. There are, however, two conceptual difficulties not adequately addressed by this study. It is not clear that the low pressure donor right ventricle actually contributes anything to the pulmonary circulation or that its pulmonic valve ever opens. The hemodynamic data presented suggest that donor RV pressure is always less than pulmonary artery pressure. If this is the case, the donor pulmonic valve will never open and the potential for thrombus formation in the donor RV will be high.
Second, and as the authors acknowledge, the recipient interventricular septum becomes a right ventricular free wall after excision of the recipient LV. The absence of the higher pressure LV will almost surely cause the shape of the RV to change and become unphysiologically spherical. This may have important consequences for long term recipient RV function that must be elucidated before this technique can be applied clinically.
The paper raises other questions: one justification for development of this technique is the authors’ assessment of the poor outcome when right heart failure complicates cardiac transplantation. The high mortality rates they cite may not represent the expected results when right heart mechanical assist is employed in a timely fashion at experienced centers. In fact, the argument could be made that anticipatory use of RV assist in patients with pre-transplant pulmonary hypertension is a more efficient strategy than an operation that leaves a patient with a dead-end aortic valve and a donor right ventricle that ejects no blood.
In addition, the long right atrial, aortic, and pulmonary artery connections may be susceptible to kinking, especially in clinical situations in which prior surgery or abnormal recipient physiology may distort the anatomy. Finally, it is not clear that it would be easy to biopsy the donor heart reproducibly given the tortuous venous pathway to the donor RV endocardium.
One of the potential benefits of this procedure is that it may make heart transplantation an option for patients with severe pulmonary hypertension who otherwise might be considered ineligible for the procedure. While it is hard to argue against extending the benefit of a useful therapy, expanding the recipient pool could make the donor heart shortage worse.
Related Article
Ann. Thorac. Surg. 2000 69: 1858-1863.
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