Related Experiment Videos
Left ventricular systolic and diastolic function in the hypertrophied ventricle
1First Department of Internal Medicine, Mie University, Tsu, Japan.
Insights
Cardiac hypertrophy impairs diastolic function in both hypertrophic cardiomyopathy (HCM) and hypertension (HT). While systolic function is preserved, impaired relaxation and filling characterize diastolic dysfunction in these conditions.
Area of Science:
- Cardiovascular Medicine
- Cardiac Physiology
- Diagnostic Imaging
Background:
- Cardiac hypertrophy, a thickening of the heart muscle, can affect both systolic and diastolic function.
- Systemic hypertension (HT) and hypertrophic cardiomyopathy (HCM) are common causes of cardiac hypertrophy.
- Understanding the specific functional impairments in these conditions is crucial for patient management.
Purpose of the Study:
- To investigate left ventricular (LV) systolic and diastolic function in patients with cardiac hypertrophy.
- To compare LV function in patients with systemic hypertension (HT) and hypertrophic cardiomyopathy (HCM) against normal subjects.
- To identify characteristic findings of diastolic dysfunction in LV hypertrophy.
Main Methods:
- Analysis of LV pressure using catheter tip-manometer.
- Simultaneous LV cineangiography with frame-by-frame digitization.
- Computation of LV volume, wall thickness, and circumferential wall stress.
Main Results:
- Normal or supernormal LV systolic pump function observed in both HT and HCM groups.
- Myocardial contractility, assessed by end-systolic wall stress-volume relation, was depressed in HCM but maintained in HT.
- Impaired LV diastolic function was evident in both HCM and HT, characterized by prolonged isovolumic relaxation, delayed filling, and decreased distensibility.
Conclusions:
- Cardiac hypertrophy, irrespective of cause (HT or HCM), leads to significant diastolic dysfunction.
- Diastolic abnormalities, including impaired relaxation and filling, are present even when systolic function appears normal.
- Potential mechanisms include myocardial ischemia or calcium overload, warranting further investigation.
Abstract:
To investigate left ventricular (LV) systolic and diastolic function in cardiac hypertrophy, we analysed LV pressure (catheter tip-manometer) and simultaneously performed cineangiography in 24 patients with systemic hypertension (HT), 25 patients with hypertrophic cardiomyopathy (HCM) and 25 normal subjects. We digitized LV cineangiograms frame by frame and computed volume and its derivatives, wall thickness and circumferential wall stress. LV systolic pump function was normal or supernormal in HT and HCM. However, myocardial contractility assessed by end-systolic wall stress-volume relation was depressed in HCM whereas it is normally maintained in HT. LV diastolic function was also impaired in HCM and even in HT despite normal systolic function. The LV hypertrophy group showed significantly prolonged time constant of isovolumic relaxation, increased time from end-systole to the peak filling rate, and upward shift of the diastolic pressure-volume relationship. The characteristic findings of LV diastolic function in LV hypertrophy, therefore, can be summarized as impaired isovolumic relaxation, delayed early diastolic filling and decreased diastolic distensibility. The mechanisms of abnormal systolic and diastolic function may include myocardial ischemia and/or calcium overload in hypertrophied myocardium, but further study will be needed to clarify these problems.