Effects of paced counterpulsation on exercise capacity and hemodynamics after heterotopic heart transplantation

Heterotopic heart transplant: relevance as Bio-VAD in emerging economies

Despite the introduction of mechanical circulatory assist systems in India two decades ago, there has not been their wide usage due to two main reasons: (1) economic-financial unaffordability and (2) lack of social support. There have been a number of significant steps taken by the government and by the media for augmenting awareness for organ donation. A sizeable donor pool in India falls into the category of marginal donors, due to a variety of reasons like geographical distances, lack of rapid transport, suboptimal donor management due to the lack of resources, and trained manpower in hospitals where donor harvest is done. Consequently, the usage of the heart as a donor organ is less than 20% in India. There is a lack of statistical data regarding the usage of heterotopic heart transplants, due to the absence of a registry, since the procedure is rarely performed, and comparative results are difficult to obtain due to different subsets of both donors and the recipients. The original papers by Barnard and Cooper cannot be extrapolated in the modern context, as these publications were in the pre-cyclosporin era. Orthotopic heart transplantation (OHT) is a well-established and commonly utilized procedure for patients with end-stage heart failure. Heterotopic heart transplantation (HHT) is a surgical procedure that allows the graft to be connected to the native heart in a parallel fashion to provide a kind of biological biventricular or univentricular (left ventricular support). It was performed first in human beings by Barnard in 1974 [S, J., 49:, Afr, Med, 1975, 303-12].

Heterotopic heart transplantation: where do we stand?

Orthotopic heart transplantation (OHT) is a well established and commonly utilized procedure for end-stage heart failure patients. Heterotopic heart transplantation (HHT) is a surgical procedure that allows the graft to be connected to the native heart in a parallel fashion. The main advantage of HHT is to assist the patient's native heart and to maintain circulation in the cases of severe acute rejection. HHT has also been proposed to overcome pulmonary hypertension, to increase the size of the donor pool and to decrease waiting times without increasing morbidity caused by the procedure. However, only a few papers have reported the short- or long-term results of HHT, and most of these studies have included <30 cases. OHT remains the standard technique and is preferable whenever the patient meets the current criteria and a suitable organ is available. HHT is far less useful than in the past because of the major advances in immunosuppression therapy and the development of long-term mechanical circulatory support. This study reviews the origin of HHT and discusses clinical developments, including their advantages and disadvantages.

Orthotopic retransplantation in heterotopic transplant recipients: 3 case reports

We report 3 patients who initially underwent heterotopic transplantation due to a size mismatch but then later underwent orthotopic retransplantation because of heart failure. In each case, the heterotopic graft was left in place, the native heart was removed, and the new allograft was placed orthotopically. This technique resulted in reduced postoperative morbidity and excellent long-term outcomes.

Demonstrating time sequence and extent of sustained decrease in native heart ejection fraction after heterotopic transplantation

BACKGROUND

In this study we investigate the time sequence and extent of the sustained decrease in native heart ejection fraction (EF) after heterotopic heart transplantation (HHTx) when using gated cardiac blood pool scanning (GCBPS) and transthoracic echocardiography (TTE) One case report of 2 patients used post-operative GCBPS and TTE and found a significant deterioration in native heart EF post-operatively over the course of several years. Comparison with pre-operative measurements using these techniques in a series of patients has not been performed previously.

METHODS

Thirteen of 16 HHTx patients with adequate pre- and post-operative GCBPS follow-up were included in this study. All patients also underwent TTE post-operatively and the GCBPS results were correlated with the TTE findings.

RESULTS

GCBPS demonstrated a marked (21.1 +/- 4.7% vs 10.5 +/- 3.7%, p < 0.0001) decrease in native EF post-HHTx. Spontaneous echo contrast in the native left ventricle and/or poor opening of the mitral/aortic valves was noted at Day 1 in 4 of 5 patients who had a TTE at this stage. No further decline was noted between the first and last post-operative GCBPS (10.8 +/- 3% vs 8.6 +/- 2.1%, p = NS).

CONCLUSIONS

A dramatic decrease in native heart EF post-HHTx occurs as early as Day 1 post-transplant. Dissociation of ventricular contraction is the most likely cause. Studies have demonstrated that paced linkage (counterpulsation) between the ventricles results in improved hemodynamics. This may have clinical implications as to the timing of ejection of blood from a left ventricular assist device (LVAD) and for providing the best hemodynamics for the ventricle being assisted and for optimizing its chances of long-term recovery.

Electrical connection of native and transplanted sinus nodes via atrial to atrial pacing improves exercise performance after cardiac transplantation

Chronotropic incompetence limits exercise performance in cardiac transplant patients. Electrical linkage of the innervated native sinus node and the denervated donor atrium or direct donor atrium pacing improves exercise performance in patients early after transplant.