Sequentially paced heterotopic heart transplant in the left chest provides improved circulatory support for the failed left ventricle

To hit a home run as a heterotopic heart recipient-living with two hearts for over three decades: a case report

Heterotopic heart transplantation (HHT) is an alternative to the orthotopic technique in selected patients with terminal heart failure. We report the case of the longest survival after HHT, with an uneventful follow-up for over three decades after transplantation. At the age of 25 years, endomyocardial fibrosis following myocarditis rendered the patient's native heart unable to maintain the body's needs. An allograft provided a second chance at life. The HHT technique was favoured due to severe pulmonary hypertension. The patient had an uneventful follow-up since then. The scarcity of donors and the revolutionary advances in the mechanical circulatory device field restricted the utilization of the HHT technique, but it has the potential to provide an excellent prognosis with a good quality of life.

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].

Two hearts synchronized each other with a DDD pacemaker

: We describe the case of a patient with dyspnea and heterotopic cardiac transplant, ventricular fibrillation from the native heart and sinus rhythm from the transplanted one. The two hearts were synchronized with a pacemaker. Electric external cardioversion and a different type of pacemaker stimulation were successfully performed, with improving symptoms.

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.

Stable ventricular fibrillation in a heterotopic heart transplant recipient

We present an unusual case of ventricular fibrillation in a conscious patient symptomatic for chest pain and shortness of breath. Almost 20 years ago he underwent heterotopic cardiac transplantation for the treatment of severe idiopathic cardiomyopathy. In the precyclosporine era, this technique was extremely useful because of the high rate of graft rejection in which the maintenance of the native heart could prevent patient death. To date, with the improvements in immunosuppressive therapy, it is generally reserved to a specific subset of conditions. A coronary angiography and a cardiac MRI confirmed the diagnosis. Six months follow-up ECG was unchanged suggesting the persistence of a double heart rhythm in the same body.

Autonomic reflexes in heterotopic heart transplantation

Heterotopic heart transplantation (HHT) is useful in the setting of irreversible pulmonary hypertension or donor/recipient size mismatch. The resulting pump is composed of two hearts attached to one another. Autonomic tone can be lost in orthotopic heart transplantation, but HHT is unique in that the donor heart lacks an autonomic nervous supply. This is relevant in terms of increasing cardiac output for example during exercise. We document altered autonomic tone in two of our patients who underwent HHT, and discuss the bearing this has on cardiac function.

Effect of a neutrophil elastase inhibitor (ONO-5046 Na) on ischemia/reperfusion injury using the left-sided heterotopic canine heart transplantation model

BACKGROUND

Ischemia/reperfusion injury is a major cause of transplanted heart dysfunction. Several reports have demonstrated that polymorphonuclear neutrophil (PMN) elastase derived from the activated neutrophils might play an important role in this injury. Herein, we investigated the protective effects of PMN elastase inhibitor (ONO-5046 Na) on ischemia/reperfusion injury using a left-sided canine heterotopic heart transplantation model.

METHODS

We used 10 pairs of adult beagle dogs. The donor heart was transplanted heterotopically into the left thoracic cavity of the recipient without cardiopulmonary bypass. A bolus of ONO-5046 Na (10 mg/kg) was introduced intravenously to 5 recipients (group II) at 15 minutes before reperfusion and was followed by continuous infusion (10 mg/kg per hour) for 180 minutes. Five dogs (group I) did not receive ONO-5046 Na and thus served as a control. After reperfusion, we evaluated transplanted heart function and obtained blood samples from the coronary sinus over a 360-minute period.

RESULTS

E(max) and pre-load recruitable stroke work in group II showed significantly better recovery than group I. Blood levels of PMN elastase, creatine kinase MB, lactate and inflammatory cytokines (tumor necrosis factor-alpha, interleukin-6, interleukin-8) were significantly lower in group II. Depletion of myocardial concentration of adenosine triphosphate at 120 minutes after reperfusion and myocardial water content was significantly lower in group II.

CONCLUSIONS

ONO-5046 Na, which inhibits PMN elastase, could reduce ischemia/reperfusion injury in heart transplantation. These results indicate that clinical application of ONO-5046 Na should be considered.

Hemodynamic and metabolic effects of paced linkage following heterotopic cardiac transplantation

BACKGROUND AND PURPOSE

Heterotopic cardiac transplantation is a valuable surgical technique that maximizes the use of donor organs. However, recipient heart function may decline steadily postoperatively with resulting clinical deterioration. Paced linkage has the potential of reducing afterload and enhancing coronary flow of both hearts, thereby improving recipient- and donor-heart function. This may have long-term as well as short-term benefits.

METHODS AND RESULTS

The study was performed on 11 heterotopic transplant recipients. The two hearts were linked with a pacemaker (paced linkage) to produce recipient heart systole during different periods of donor-heart diastole. The recipient ventricular contraction was timed to occur during early, mid, and late diastole of the donor heart. Hemodynamic baseline measurements were compared with the optimal counterpulsated data. Paced linkage produced significant improvements in total cardiac output, 5.0 +/- 0.9 compared with baseline 4.5 +/- 0.8 L/min (P = .021); recipient coronary sinus flow, 278 +/- 145 versus 186 +/- 108 mL/min (P = .022); and aortic systolic pressure, 135 +/- 27 versus 123 +/- 27 mm Hg (P = .005). There was an overall improvement in systolic ventricular performance in the recipient heart when pace linked, as evidenced by a significant increase in left ventricular systolic pressure of 118 +/- 36 compared with the baseline value of 108 +/- 33 mm Hg (P = .016), an increase in ejection period from 174 +/- 30 versus 203 +/- 48 (P = .046), and a decrease in the pre-ejection period of 147 +/- 37 when paced versus 181 +/- 39 milliseconds (P = .013). The metabolic studies showed a significant decrease in hypoxanthine release from a baseline level of 0.4 mumol/L to a paced value of -0.06 mumol/L (P = .002); these very low values would suggest that there is no evidence of ischemia. Hemodynamic changes in the donor heart included a significant reduction in the left ventricular end-diastolic pressure from 6.8 +/- 4.4 versus baseline of 10.5 +/- 5.8 mm Hg (P = .029) and in maximum -dP/dT from 3.2 +/- 1.7 versus baseline of 2.1 +/- 1.1.

CONCLUSIONS

Paced linkage after heterotopic cardiac transplant produces significant functional improvements in both hearts. Permanent pacemaker implantation may sustain these acute benefits and prevent the premature deterioration of the recipient heart.

Postoperative hemodynamic improvement with paced linkage of the donor and recipient hearts following heterotopic cardiac transplantation

It has been shown that following heterotopic heart transplantation the recipient left ventricle ejects more effectively when it contracts out of phase with the donor left ventricle. However, this is rarely the situation, as the two hearts beat independently of one another and the denervated donor heart tends to beat faster than the recipient. In this study the hemodynamic effects of connecting the two hearts by an external temporary dual-chamber pacemaker were evaluated. The donor right ventricle was sensed and the recipient right atrium paced after a timed delay. The delay was adjusted so that recipient systole coincided with donor diastole. Eleven patients were studied in the first postoperative day. Pacing resulted in an improvement in cardiac output from 5.0 to 5.6 l/min (p = 0.003) and a reduction in pulmonary capillary wedge pressure from 16 to 12 mmHg (p = 0.0035). This was associated with a 35% reduction in inotrope requirements. It is concluded that sequential pacing of the two hearts is a useful adjunct to inotropic support in the postoperative period.

Heterotopic heart transplantation and native heart ventricular arrhythmias

Heterotopic heart transplantation has been said to be contraindicated in patients with serious native heart arrhythmias that produce hemodynamic instability. Placement of heterotopic allografts, however, can theoretically act as a biological biventricular assist device to provide hemodynamic support during these unstable rhythms. Further, this operation might beneficially alter the hemodynamic milieu of heart failure such that the arrhythmias are ameliorated. Described is our experience with 4 patients with heart failure receiving heterotopic cardiac allografts, documenting changes in native heart arrhythmia that occurred. These cases demonstrate that heterotopic grafts can adequately sustain hemodynamics during malignant native heart dysrhythmia. We believe native heart ventricular arrhythmias are not a contraindication to heterotopic heart transplantation.