Diastolic function in heart transplant: From physiology to echocardiographic assessment and prognosis

Abstract

Heart transplant (HTx) still represents the most effective therapy for end-stage heart failure, with a median survival time of 10 years. The transplanted heart shows peculiar physiology due to the profound alterations induced by the operation, which inevitably influences several echocardiographic parameters assessed during these patients' follow-ups. With these premises, the diastolic function is one of the main aspects to take into consideration. The left atrium (LA) plays a key role in this matter, and that same chamber is significantly impaired with the transplant, with different degrees of altered function based on the surgical technique. Therefore, the traditional echocardiographic evaluation of diastolic function applied to the general population might not properly reflect the physiology of the graft. This review attempts to provide current evidence on diastolic function in HTx starting from defining its different physiology and how the standard echocardiographic parameters might be affected to its prognostic role. Furthermore, based on the experience of our center and the available evidence, we proposed an algorithm that might help clinicians distinguish from actual diastolic dysfunction from a normal diastolic pattern in HTx population.

Keywords: diastolic function; echocardiography; heart transplant; physiology; prognosis.

FIGURE 1

Surgical techniques for orthotopic heart transplant. Picture (A) shows the biatrial technique in which the anastomoses are at the mid-level of the left and right atria in addition to the aortic and pulmonary artery anastomoses. Picture (B) depicts the bicaval technique, the most commonly used nowadays, in which separate superior and inferior vena cava anastomoses are made instead of the right atrial anastomosis. Finally, picture (C) shows the total orthotopic heart transplant technique, which is a complete atrioventricular cardiac transplantation with separate cava and pulmonary vein anastomoses. Kindly readapted from Badano et al. (16). Dotted lines, original position of excised native heart; Ao, aorta; IVC, inferior vena cava; LA, left atrium; LAC, left atrial cuff; LPVC, left pulmonary vein cuff; PA, pulmonary artery; RA, right atrium; RPVC, right pulmonary vein cuff; SVC, superior vena cava.

FIGURE 2

Echocardiographic assessment of diastolic function in heart transplant. This figure shows a mitral E/A ratio ≥2 with a deceleration time of E wave of 151 ms, thus indicating a possible restrictive filling pattern in a 3-year heart transplant patient. However, TDI analysis, shown in the middle and right pictures, shows normal e’ lateral and septal velocities, thus possibly excluding a restrictive filling pattern.

FIGURE 3

Proposed algorithm to evaluate diastolic function in heart transplant patients. The first step in the evaluation of diastolic function in HTx is assessing mitral inflow velocities. In the case of an E/A ratio <2 high LV filling pressure can be fairly excluded. On the other hand, if the E/A ratio >2, it is useful to evaluate TDI-derived velocities. However, when their values lie in a gray zone, DT and E/e’ ratio should be considered. If these latter two indexes together cannot exclude high LV filling pressure, additional parameters should be used, such as LAVi (in the case of bicaval technique), LA strain, and LV-GLS and TR velocity. This is the diagnostic algorithm proposed by our center, based on the values derived from the study by Ingvarsson et al. (5). BSA: body mass index; DT: deceleration time; HTx: heart transplantation; LA: left atrial; LAVI: left atrial volume index; LV: left ventricular; LVGLS: left ventricular global longitudinal strain; MV: mitral valve; PALS: peak atrial longitudinal strain; TR: tricuspid regurgitation.