A Comparative Study of Systolic and Diastolic Mechanical Synchrony in Canine, Primate, and Healthy and Failing Human Hearts

Abstract

Aim: Mechanical dyssynchrony (MD) is associated with heart failure (HF) and may be prognostically important in cardiac resynchronization therapy (CRT). Yet, little is known about its patterns in healthy or diseased hearts. We here investigate and compare systolic and diastolic MD in both right (RV) and left ventricles (LV) of canine, primate and healthy and failing human hearts.Methods and Results: RV and LV mechanical function were examined by pulse-wave Doppler in 15 beagle dogs, 59 rhesus monkeys, 100 healthy human subjects and 39 heart failure (HF) patients. This measured RV and LV pre-ejection periods (RVPEP and LVPEP) and diastolic opening times (Q-TVE and Q-MVE). The occurrence of right (RVMDs) and left ventricular systolic mechanical delay (LVMDs) was assessed by comparing RVPEP and LVPEP values. That of right (RVMDd) and left ventricular diastolic mechanical delay (LVMDd) was assessed from the corresponding diastolic opening times (Q-TVE and Q-MVE). These situations were quantified by values of interventricular systolic (IVMDs) and diastolic mechanical delays (IVMDd), represented as positive if the relevant RV mechanical events preceded those in the LV. Healthy hearts in all species examined showed greater LV than RV delay times and therefore positive IVMDs and IVMDd. In contrast a greater proportion of the HF patients showed both markedly increased IVMDs and negative IVMDd, with diastolic mechanical asynchrony negatively correlated with LVEF.Conclusion: The present IVMDs and IVMDd findings have potential clinical implications particularly for personalized setting of parameter values in CRT in individual patients to achieve effective treatment of HF.

Abnormal inter-ventricular diastolic mechanical delay in patients with ST-segment elevation myocardial infarction

“…As mentioned in a previous study [ 10 ], the inflow spectrums of the pulsed-wave Doppler across the mitral and tricuspid valve were recorded in apical four-chamber views. The diastolic opening times of the left and right ventricle were measured as the interval between the onset of the QRS complex and the beginning of the E wave for the mitral valve (Q-MV E ) and tricuspid valve (Q-TV E ), respectively (Fig.…”

“…Previous research has shown that Doppler echocardiography-measured inter-ventricular mechanical dyssynchrony can help predict prognosis in ischemic and non-ischemic dilated cardiomyopathies [ 7 , 8 ], acute myocardial infarction [ 4 ], and coronary artery disease [ 9 ]. Our previous study [ 10 ] had proved that diastolic ventricular relaxation sequence in normal hearts was highly consistent, with the right ventricle filling before the left ventricle. This indicated that diastolic opening time of the tricuspid value (Q-TV E ) was less than that of the mitral valve (Q-MV E ), and we defined this differences as left ventricular diastolic mechanical delay (LVMDd) [ 10 ].…”

“…Our previous study [ 10 ] had proved that diastolic ventricular relaxation sequence in normal hearts was highly consistent, with the right ventricle filling before the left ventricle. This indicated that diastolic opening time of the tricuspid value (Q-TV E ) was less than that of the mitral valve (Q-MV E ), and we defined this differences as left ventricular diastolic mechanical delay (LVMDd) [ 10 ]. However, in patients with HF, the percentage of right ventricular diastolic mechanical delay (RVMDd) increased significantly [ 10 ].…”

“…This indicated that diastolic opening time of the tricuspid value (Q-TV E ) was less than that of the mitral valve (Q-MV E ), and we defined this differences as left ventricular diastolic mechanical delay (LVMDd) [ 10 ]. However, in patients with HF, the percentage of right ventricular diastolic mechanical delay (RVMDd) increased significantly [ 10 ]. This study aimed to explore further the ventricular mechanical relaxation pattern and its influences on patients with ST-segment elevation myocardial infarction (STEMI).…”

Frequency of Left Ventricular Mechanical Dyssynchrony in Chronic Heart Failure

“…Selecting the best candidates for CRT is crucial. It is probable that echocardiographic measurements of mechanical dyssynchrony are more useful in predicting who may benefit from CRT [5][6][7]. Tissue Doppler imaging (TDI) has been demonstrated to be a reliable predictor of responsiveness after CRT, especially in cases where mechanical dyssynchrony was present.…”