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.
Highlights
Heart failure (HF), a condition associated with high mortality and morbidity, constitutes a major and growing worldwide public health problem [1,2,3,4], resulting in a requirement for the development of effective management
We have demonstrated for the first time that (a) normal animal and human hearts show greater left than right delay times and positive systolic (IVMDs) and diastolic interventricular mechanical delay (IVMD) delays (IVMDd). (b) In contrast, a greater proportion of individual HF patients show reversals in both these IVMDs and IVMDd trends
We report a predominance of left ventricular mechanical delay in systole (LVMDs) (76.9, 55.9, and 74.0% respectively) and highly consistent diastolic filling patterns (LVMDd) (93.3, 98.3, and 81.0% respectively) on the basis of paired comparisons of left ventricle (LV) and right ventricle (RV) parameters in each subject, in normal canine, primate and human hearts
Summary
Heart failure (HF), a condition associated with high mortality and morbidity, constitutes a major and growing worldwide public health problem [1,2,3,4], resulting in a requirement for the development of effective management To this end, cardiac resynchronization therapy (CRT) implantation has proved useful as a therapeutic strategy for managing HF [5, 6]. CRT likely addresses the association of HF with mechanical dyssynchrony (MD) or disparities in wall contraction timing [8] This may reflect the importance of variations in the contributory factors for HF in individual patients. Previous experimental reports had positively correlated durations of canine ventricular depolarization and repolarization intervals with wall thickness and cardiac size The latter potentially alter in HF [11] causing both proarrhythmic effects [12, 13] and mechanical dyssynchrony.
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