Echocardiographic assessment of ventricular size and function in heart transplant patients

Abstract: AbstractThe overall aims of this thesis were to use echocardiography to non-invasively, delineate early structural andfunctional changes following orthotopic heart transplantation (OHT), and to define reference values in the contextof gender and bridging with mechanical circulatory support.Several factors might affect myocardial function in OHT patients rendering the use of normal values fortransthoracic echocardiography derived from healthy subjects unsatisfactory. Recent echocardiographic referencevalues have been specified by gender but the disparity in relation to gender and gender mismatch between donorand recipient has not been studied in the OHT cohort. Early ventricular adaptation following OHT is sparselystudied, and specific reference values adapted to this unique cohort are abscent. Moreover, the impact of preconditioningwith left ventricular assist device (LVAD) used in a growing number of end-stage heart failure patientsawaiting OHT needs further evaluation. Speckle tracking derived strain has gained increasing interest due to itsability to detect discrete changes in myocardial contractility. The possible additive value of this echocardiographicparameter to assess left- and right- (LV and RV) ventricular function in the OHT cohort warrants furtherinvestigation.The results of this thesis delivers the findings that atrial enlargement is present and ventricular size and function isaltered in OHT patients. In terms of measures of LV function, ejection fraction (EF) and LV global longitudinalstrain (LVGLS) along with all measures of RV function were reduced compared to reference values for the normalpopulation. With regard to gender we found that male recipients had larger LV mass, thicker septal wall and largerLV volume. A slightly higher EF was detected in female recipients vs. male recipients whereas no differences wereobserved for conventional RV function parameters between the genders. Both LV- and RV- ventricular strain washigher in females than in males. The male recipients receiving a female donor heart had comparable EF and strainparameters to the female recipients receiving a gender-matched heart. Analysis of early adaptation following OHTrevealed that LV function parameters remained stable between one and twelve months after OHT while acontinuous improvement in RV function parameters, including strain, was seen. In patients bridged with LVAD wefound that RV adaptation post OHT was accelerated and the values of echocardiographic function parametersobtained at one month remained unaltered during twelve months follow-up. Thus, at twelve months differencesbetween the groups were no longer detectable.To conclude, the distribution of several routinely used echocardiographic measures differ in stable OHT patientsas compared to healthy subjects suggesting that specific reference values should be applied when assessingnormality in this cohort. The fact that rejection is more common early following transplantation supports theimportance of defining values of early normal adaptation in order to tailor the examination to detect adverseevents. Moreover, the knowledge regarding how recipient gender and preconditioning with LVAD affect ventricularfunction following OHT is clinically relevant to adequately examine OHT patients with echocardiography.