**1. Introduction**

By August of 1975 [1], 277 patients had received an orthotopic heart transplantation and 49 were alive. The longest survivor lived 6.8 years.

Christian Barnard reported the heterotopic heart transplant (HHT) technique. In 1976 [1], Barnard noted the benefits of heterotopic heart transplantation to be that the donor heart acts as an assist device, assists during episodes of rejection, can be removed in case of severe graft rejection, and still the patient may receive a subsequent heart transplant. Barnard et al. [2] published a case report of a heterotopic heart transplant recipient that suffered acute rejection and was supported by the native heart while the heterotopic graft recovered.

At the time the paper was written, cyclosporine was not used for post-heart transplantation and the incidence of acute rejection was more common. The heterotopic heart transplant technique offered an extra layer of prevention and/or treatment during the pre-cyclosporine

era when death within 24 hours of the onset of rejection was common. In addition, to the benefits from treatment of acute rejection, the heterotopic heart transplantation technique allows selected recipients with pulmonary hypertension to receive a transplant.

to 13 mmHg), (2) donor to recipient weight ratio of less than 0.8, (3) anticipated ischemic time greater than 6 hours, and (4) a marginal donor heart. Marginal donors were described as those that required high inotropic support, had a history of a cardiac arrest or arrhythmia, wall motion abnormalities on the echocardiogram, and/or ischemic changes on the electrocardiogram (EKG). Fourteen of the donor hearts were marginal and had been declined by other

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In the study of Newcomb et al. [5], the heterotopic heart transplant recipients were significantly older (mean 58 years vs. 47.1 years for OHT); the donors were also significantly older (mean age 45.2 years vs. 34.5 years for OHT). The ischemic time was also much higher for the HHT recipients; 366 minutes vs. 258 minutes for OHT. The intensive care unit and the total length of the hospital stay was higher for HHT recipients; though, not statistically significant. The study demonstrated lower survival for heterotopic heart transplant recipients compared to orthotopic heart transplant recipients in the same time period; though, the survival benefit for OHT recipients disappeared when they performed a subgroup analysis for the recipients who had elevated pulmonary artery pressures. The study demonstrates the successful use of the heterotopic heart transplant. The survival in HHT recipients were not as good as in those of OHT recipients because of the HHT technique was more often used in marginal donors and more high-risk recipients. Marginal donor hearts may not have performed as well in OHT recipients. Furthermore, high risk recipients have decreased survival expectations especially

Boffini et al. [6] described their single center experience with the heterotopic heart transplant; and, found the HHT to be comparable to OHT. HHT was used between in 1985–2003, in 12 patients [(1.7%) of the all the heart transplant performed during that time]. The 1-year and 5-year survival was 92 and 64% respectively. These results demonstrated when the HHT technique is used in the usual recipient risk patient, the outcomes can be effective and acceptable for recipients. The HHT technique was used for body size mismatch in 11 patients and

In addition to donor-recipient size mismatch, elevated pulmonary vascular resistance (PVR), and, fixed pulmonary hypertension are also indications for HHT. Vassileva et al. [7] reviewed 18 recipients with fixed pulmonary vascular resistance who received a HHT with the donor pulmonary artery anastomosed to the recipient right atrium. The indications were

(PA) systolic pressure > 60 mmHg. All of the recipients had some degree of pulmonary hypertension, and, 8 of the patients had a restrictive cardiomyopathy. Twelve of the patients were New York Heart Association class III or IV; the remaining six were in the hospital with continuous inotropic support, and, one was intubated. The mean aortic cross clamp time was 58 minutes and a mean ischemic time of 122 minutes. The follow-up right heart catheterizations demonstrated a progressive decrease in the pulmonary artery pressures after transplant with a mean systolic pulmonary artery pressure of 29 mmHg, a TPG of 10 mmHg, and, a

patients with elevated, and/or, fixed pulmonary artery pressures, and, elevated pulmonary

, (2) transpulmonary gradient (TPG) > 15 mmHg, or, (3) pulmonary artery

. The group concluded that the HHT technique was a valuable option for

centers. Most of the HHT recipients had more than one indication for an HHT.

with the use of a marginal donor heart.

1 recipients for a marginal donor heart.

(1) PVR > 6 units/m<sup>2</sup>

PVR of 3.7 units/m<sup>2</sup>

vascular resistance.
