Presentation
Routine follow-up. Patient is currently well.
Patient Data
The patient's unusual cardiomediastinal contour is accounted for by a history of heterotopic heart transplantation. There is a native heart with a left ventricular aneurysm on the left, and the slightly smaller donor heart next to it on the right.
CT demonstrates the left anatomic connections in a heterotopic transplant. In the surgical approach used in this patient, only the left heart vessels are anastomosed ("left ventricular assist"). The alternative "bi-ventricular assist" approach would also anastomose donor and native main pulmonary arteries1.
Note the relatively small donor heart, native heart with calcified left ventricular aneurysm and calcified coronary arteries (reflecting underlying ischemic etiology), dense liver which is likely due to amiodarone in this patient.
Case Discussion
The technique of heterotopic (as opposed to the more conventional orthotopic) cardiac transplantation involves the anastomosis of a donor heart alongside the native heart, resulting effectively in a double heart.
It is thought to have advantage in a select group of transplant patients. In particular, it may be performed in patients with refractory pulmonary hypertension, which would otherwise preclude orthotopic transplantation due to the risk of donor heart failing as it is unable to cope with the elevated right heart pressures.
It also allows transplantation when there is a mismatch between the patient size and heart size (large donor, small heart). In this situation, the native heart takes on an "assist device" role, contributing to the total cardiac output, and potentially supporting the circulation during the initial adaptation, and at times of transplant rejection.
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