Echocardiographic assessment of ventricular size and function in heart transplant patients

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