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Relation of hemodynamic load to left ventricular hypertrophy and performance in hypertension
Insights
Left ventricular hypertrophy in hypertension is weakly linked to blood pressure. Concentric hypertrophy relates more to elevated peripheral resistance, impacting cardiac function and increasing wall stress.
Area of Science:
- Cardiology
- Hypertension Research
- Echocardiography
Background:
- Left ventricular hypertrophy (LVH) and dysfunction in hypertensive patients often show poor correlation with blood pressure levels.
- Understanding the underlying reasons for this discrepancy is crucial for effective hypertension management.
- Essential hypertension affects a significant portion of the adult population, leading to cardiovascular complications.
Purpose of the Study:
- To investigate the relationship between blood pressure, left ventricular hypertrophy, and left ventricular performance in untreated hypertensive patients.
- To evaluate the correlation of left ventricular mass index (LVMI) and end-diocardial relative wall thickness (RWT) with blood pressure.
- To assess the association of left ventricular performance with wall stress and hemodynamic parameters.
Main Methods:
- Study included 100 untreated patients with essential hypertension (mean age 44 +/- 14 years).
- Cuff blood pressure measurements were taken.
- Quantitative echocardiography was used to assess left ventricular mass index (LVMI) and end-diocardial relative wall thickness (RWT).
Main Results:
- LVH, measured by LVMI or RWT, showed weak correlations with systolic, diastolic, and mean blood pressure (r = 0.16 to 0.32).
- End-diocardial RWT correlated positively with total peripheral resistance (r = 0.52) and inversely with cardiac index (r = -0.47).
- Left ventricular performance (fractional systolic shortening) declined significantly with increasing mean systolic wall stress (r = -0.42) and end-systolic wall stress (r = -0.71).
Conclusions:
- Left ventricular hypertrophy in hypertension is only modestly correlated with resting blood pressure.
- Concentric hypertrophy (increased RWT) is more closely related to elevated peripheral resistance, suggesting interdependence.
- Impaired left ventricular performance occurs when hypertrophy fails to offset pressure overload, leading to increased wall stress.
Abstract:
Left ventricular hypertrophy and dysfunction in patients with hypertension are often poorly related to the level of blood pressure. To evaluate the reasons for this, 100 untreated patients (44 +/- 14 years) with essential hypertension were studied using cuff blood pressure and quantitative echocardiography to measure left ventricular mass index and end-diastolic relative wall thickness as 2 indexes of left ventricular hypertrophy. Left ventricular hypertrophy, as measured by either left ventricular mass index or end-diastolic relative wall thickness, correlated weakly with all indexes of blood pressure including systolic, diastolic, and mean blood pressure (r = 0.16 to 0.32). In contrast, end-diastolic relative wall thickness, an index which assesses the severity of concentric hypertrophy, showed a closer direct relation with total peripheral resistance (r = 0.52 p less than 0.001) and a significant inverse relation with cardiac index (r = -0.47, p less than 0.001). Left ventricular performance as assessed by fractional systolic shortening of left ventricular internal dimensions was not significantly related to left ventricular mass index, blood pressure, or peak systolic wall stress, but declined significantly with increasing mean systolic wall stress (r = -0.42, p less than 0.001) and even more with increasing end-systolic wall stress (r = -0.71, p less than 0.001). It is concluded that in patients with hypertension (1) left ventricular hypertrophy is correlated only modestly with measurements of resting blood pressure; and (2) the classic pattern of concentric left ventricular hypertrophy, as measured by relative wall thickness, is more closely related to the "typical" hypertensive abnormality of elevated peripheral resistance, suggesting that these anatomic and hemodynamic changes may be pathophysiologically interdependent. Furthermore, left ventricular performance declines when the pressure overload in hypertension is not offset by compensating hypertrophy, allowing wall stresses to increase.