Right heart morphology and function in heart transplantation recipients

BACKGROUND: The right heart is a major determinant of prognosis in cardiac transplant recipient patients. AIM: To investigate right ventricular morphology and function and their relationship with exercise capacity in cardiac transplant recipient patients using standard tranthoracic echocardiography and a new three-dimensional echocardiographic software adapted for right ventricular analysis. METHODS: One hundred fifteen relatively stable cardiac transplant recipient patients (71 men; 58.3 ± 5.8 years; 7.8 ± 4.5 years after transplantation) and 80 healthy age-comparable and sex-comparable controls underwent standard echocardiography, tissue Doppler imaging (TDI), and three-dimensional echocardiography, focused on the right ventricular analysis. Along with left heart parameters, right ventricular measurements included end-diastolic diameters at basal and mid-cavity level; base-to-apex length; tricuspid annulus plane systolic excursion (TAPSE); TDI right ventricular systolic peak velocity (Sm); and three-dimensional ejection fraction. Using the peak systolic tricuspid regurgitation velocity (TRV) and the end-diastolic pulmonary regurgitation velocity, the modified Bernoulli equation was used to calculate the pulmonary artery systolic (PASP) and diastolic pressures. Pulmonary artery vascular conductance (PAVC) was estimated by left ventricular stroke volume/4 × (TRV - pulmonary regurgitation velocity). RESULTS: Left ventricular diameters and ejection fraction did not significantly differ between the two groups, whereas mass index was increased in cardiac transplant recipient patients (P < 0.01). Right ventricular diameters were significantly increased (P < 0.001), whereas TAPSE and right ventricular Sm were significantly lower in cardiac transplant recipient patients. Conversely, in cardiac transplant recipient patients, three-dimensional right ventricular ejection fraction (RVEF) was not significantly reduced (P < 0.001), whereas both PASP and PAVC were impaired. By multivariable analysis, age at transplantation (P < 0.01) and pulmonary artery mean pressure (P < 0.001) were the only independent determinants of right ventricular diameters and RVEF in cardiac transplant. Furthermore, RVEF measured by real-time three-dimensional echocardiography was a powerful independent determinant of functional capacity in cardiac transplant recipient patients. CONCLUSION: Despite the reduction of right ventricular performance along the long axis suggested by TAPSE and right ventricular Sm, the increased right ventricular diameters along with absence of a decrease in three-dimensional RVEF support the hypothesis of geometrical rather than functional changes of the right ventricle in cardiac transplant recipient patients.