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Disparate difference in preload reserve between myocardial hypertrophy due to essential hypertension and hypertrophic
M Mukai1, M Hamada, T Sumimoto
12nd Department of Internal Medicine, Ehime University School of Medicine, Japan.
Insights
Essential hypertension preserves left ventricular preload reserve, similar to normal subjects. However, hypertrophic cardiomyopathy impairs this reserve, indicating distinct cardiac responses to increased preload.
Area of Science:
- Cardiology
- Physiology
Background:
- Essential hypertension can lead to myocardial hypertrophy.
- Hypertrophic cardiomyopathy is characterized by abnormal heart muscle thickening.
- Left ventricular preload reserve is crucial for maintaining cardiac output.
Purpose of the Study:
- To compare left ventricular preload reserve in essential hypertensives, hypertrophic cardiomyopathy patients, and normal subjects.
- To assess the impact of the legs-up procedure on systolic time intervals and stroke volume index.
Main Methods:
- The legs-up procedure was performed on all participants.
- Measurements included stroke volume index and systolic time intervals (left ventricular ejection time, pre-ejection period, PEP/ET ratio).
- Blood pressure, heart rate, and plasma catecholamine levels were monitored.
Main Results:
- Essential hypertensives and normal subjects showed improved stroke volume index and adjusted systolic time intervals after the legs-up procedure.
- Patients with hypertrophic cardiomyopathy did not exhibit these changes.
- No significant changes in blood pressure, heart rate, or catecholamines were observed across groups.
Conclusions:
- Myocardial hypertrophy in essential hypertension preserves left ventricular preload reserve.
- Hypertrophic cardiomyopathy impairs the heart's ability to increase preload reserve.
- The legs-up procedure is a valuable tool for assessing preload reserve.
Abstract:
To investigate the left ventricular preload reserve in essential hypertensives, the legs-up procedure was performed and the data were compared with those in patients with non-obstructive hypertrophic cardiomyopathy and in normal subjects. Stroke volume index and the following systolic time intervals were measured before and after the legs-up procedure: left ventricular ejection time, pre-ejection period and the ratio of pre-ejection period to left ventricular ejection time (PEP/ET). No changes in blood pressure, heart rate or plasma catecholamine levels were noted before and after the legs-up procedure in all groups. A shortening in the pre-ejection period, a prolongation of ejection time, a decrease in the PEP/ET ratio and an increase in the stroke volume index were observed in essential hypertensives and in normal subjects. However, the changes in these parameters were not observed in patient with hypertrophic cardiomyopathy. The legs-up procedure is known to increase left ventricular end-diastolic volume. These results suggest that myocardial hypertrophy due to essential hypertension preserves the same preload reserve as in normals, but hypertrophic cardiomyopathy does not.