Heart transplantation

Heart transplantation is a major surgical procedure for acute or chronic end-stage heart disease in which the failing heart is replaced with a healthier donor heart. It requires a comprehensive multidisciplinary approach and radiology plays a major role in the evaluation of patients before and after heart transplantation.

This article does not discuss the complex medical issues around heart transplantation such as immune typing and post-operative immunosuppression.

Indications

There are several indications for transplantation and many require the exhaustion of non-surgical alternatives before transplantation is considered:

• the majority of adult transplants are for cardiomyopathy ¹

  • non-ischemic etiologies are a more common indication than ischemia

  • restrictive cardiomyopathy

  • hypertrophic cardiomyopathy

• valvular disease and cardiomyopathy

• infiltrative myocardial disease e.g. sarcoidosis

• cardiac tumors

• congenital heart disease is the most common indication in pediatric patients ¹

Types of heart transplantation

There are two main types of heart transplantation performed with medial sternotomy ¹:

• orthotopic heart transplant - the deceased donor heart is transplanted into the recipient's pericardial sac immediately following removal of the diseased heart from the recipient. This is the most common type and there are two basic methods:

  • biatrial method - the recipient’s heart is removed with a portion of the native atria (atrial cuff) left in situ to be anastomosed to the donor heart. Therefore there are only four anastomoses: two atria, aorta and pulmonary trunk. The suture line along the atrial cuff is associated with a higher rate of arrhythmias ¹. This is the original and fastest procedure.

  • bicaval method - the recipient’s heart is removed along with the native atria and multiple anastomoses are made: right atrium to the SVC and IVC and left atrium with the pulmonary veins. Therefore there are more anastomoses and the procedure takes longer than the biatrial method. As the normal anatomy of the atria is maintained there are fewer complications regarding the SA node ².

• heterotopic (or 'piggy-back') heart transplant - this is an extremely rare type of transplant in which the recipient's native heart is not removed and the deceased donor heart is placed in the recipient's mediastinum on the right of the native heart. The aorta, pulmonary trunk, IVC and SVC of the donor heart are anastomosed to the corresponding vessels of the recipient's native great vessels. It is usually performed for patients with pulmonary hypertension or those with a significant recipient-to-donor size mismatch.

The heart may also be transplanted in a combined heart-lung transplant procedure.

Cadaveric donation can be either DBD or DCD:

• DBD: donation after brain death

• DCD: donation after circulatory death

Imaging the preoperative patient

Imaging of the recipient before heart transplantation is required to identify any related anatomy or pathology that may pose technical difficulties for the surgical procedure. This includes ³:

• mediastinal fibrosis

• mediastinal adhesions such as from previous coronary artery bypass surgery

• complications from the previous sternotomy

• pulmonary venous anatomy

• systemic venous morphology

• atrial morphology (situs)

• pulmonary arterial morphology including features of pulmonary hypertension

• systemic arterial anatomy including aortic dimensions and pre-existing pathology such as extensive atheroma

• variant anatomy of the pericardium and great vessels

History and etymology

The first human-to human heart transplantation was performed in December 1967 by the South African cardiac surgeon Christiaan Neethling Barnard (1922-2001) in the Groote Schurur Hospital in Kapstadt, South Africa ⁴.