Post Heart Transplant Echocardiographic Evaluation

Recipient Evaluation

Echocardiography with Doppler interrogation is instrumental in identifying the cause of heart failure, establishing candidacy for transplantation, and monitoring for the progression of disease. Patients with elevated and irreversible pulmonary vascular resistance (>2.5 Wood units) are at significantly higher risk for fatal right heart failure after heart transplantation compared with patients who have a pulmonary vascular resistance of less than 2.5 Wood units (40.6% vs 3.8%, respectively). Pulmonary hypertension and pulmonary vascular resistance are typically evaluated by right heart catheterization in all pretransplantation evaluations. However, there is evidence to suggest echocardiography may be used as a noninvasive method to assess hemodynamics, including pulmonary hypertension and vascular resistance.

Donor Evaluation

Evaluation of the potential donor heart is critical for the outcomes after transplantation. Since its first reported use in 1988 for pretransplantation donor evaluation, echocardiography (transthoracic and transesophageal) has served an instrumental role in this evaluation because of its portability and accurate assessment of ventricular function, as well as its evaluation of valvular and structural (including congenital) abnormalities. ^,

Left ventricular (LV) systolic dysfunction, as identified on echocardiography, accounts for approximately 26% of all unused donor hearts presented for transplantation. It should be noted that LV systolic dysfunction in the absence of coronary artery disease is a common finding in patients with brain death caused by intracranial pathologies (e.g., intracranial hemorrhage); studies have reported a frequency of up to 42%. ^, This phenomenon is thought to occur as a consequence of the neuronal and humoral catecholamine surge induced by brain death. Apical sparing has been noted in these clinical circumstances because of the decreased sympathetic nerve terminals and reduced myocardial norepinephrine content in the LV apex. Ventricular dysfunction in the absence of coronary artery disease has also been identified in patients with metabolic derangements, including acidosis, anemia, hypothyroidism, and hypoxia. In these patients, LV systolic dysfunction may be a transient phenomenon, and serial imaging has been used to identify improvements in contractile function, particularly after hemodynamic and metabolic correction. The use of low-dose dobutamine stress echocardiography has been studied to identify myocardial reserve in donor hearts with LV dysfunction. Those donor hearts with improvement in systolic function had excellent posttransplant outcomes, suggesting that this may be an approach to identify donors with reversible cardiac dysfunction.

The effect of left ventricular hypertrophy (LVH) on posttransplant survival has provided conflicting results. Although a single study showed LV wall thickness greater than 1.4 cm was associated with reduced survival, others found a favorable survival in most recipients of allografts with LVH, including moderate to severe LVH (>1.4 cm). However, the presence of LVH in combination with older age (older than 55 years) or prolonged ischemic time (>4 hours) was found to increase the posttransplant mortality rate.

Limitations of donor heart evaluation with echocardiography include difficulties in image acquisition in organ donors who are receiving mechanical ventilation and in those with chest trauma.