The relationship between pressure overload hypertrophy and left ventricular muscle function is controversial. Studies in animals and humans with pressure overload hypertrophy as a result of aortic stenosis and systemic hypertension have shown both normal and reduced ejection phase indices, with and without clinical heart failure. Yet, ejection phase indices are dependent upon loading conditions. In contrast, the linear relationship between end-systolic wall stress and end-systolic volume provides an index of left ventricular muscle function which is independent of loading conditions. We have used this index to evaluate left ventricular muscle function in three patient groups: (1) Seven normal subjects (N); (2) six patients with systemic hypertension without heart failure (LVH); and (3) five patients with systemic hypertension, who had heart failure (CHF). History, physical, EKG, and echocardiography (M mode and 2-D) were used to exclude coronary disease. The mean slope of the stress-volume lines for the CHF group (1.7 ± 0.4) is significantly less (p < 0.05) than that of the N group (4.0 ± 1.6). The slope for the LVH group (2.8 ± 0.4) is between those of the N and LVH groups and is not significantly different (p > 0.05) from either. Using the more simply obtained ratio of stress to volume index at end-systole ('end systolic index') with the patient at rest also shows a low value for the CHF group (1.3 ± 0.2) which was significantly lower (p > 0.05) than both the N (2.7 ± 0.5) and LVH (2.5 ± 0.7) groups. The N and LVH groups are not significantly different (p > 0.05) from each other. The end-diastolic volume index of the CHF group (108 ± 10 cc) is significantly larger (p < 0.05) than both the N (56 ± 16) and LVH (52 ± 21) groups, but the N and LVH groups do not differ significantly (p > 0.05). We conclude that, in systemic hypertension, cardiac muscle function is initially normal, and hypertrophy maintains a normal end-systolic wall stress. However, muscle function eventually begins to deteriorate. Then, despite marked hypertrophy, there is an elevation of the end-diastolic volume, and eventually symptoms of heart failure develop.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Cardiovascular Ultrasonography|
|State||Published - Jan 1 1983|
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