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Left ventricular filling in arterial hypertension. Influence of obesity and hemodynamic and structural confounders
G F Mureddu1, G de Simone, R Greco
1Department of Clinical and Experimental Medicine, Federico II University Hospital School of Medicine, Naples, Italy.
Insights
Arterial hypertension and obesity both prolong isovolumic relaxation time, a measure of heart relaxation. Left ventricular filling abnormalities in hypertension are explained by increased left ventricular mass.
Area of Science:
- Cardiology
- Physiology
- Medical Imaging
Background:
- Left ventricular filling is crucial for cardiac function.
- Arterial hypertension and obesity are prevalent conditions affecting cardiovascular health.
- Understanding their impact on diastolic function is essential.
Purpose of the Study:
- To assess the relationship between left ventricular filling, cardiac load, and geometry in hypertensive and normotensive individuals, with and without obesity.
- To identify predictors of prolonged isovolumic relaxation time.
Main Methods:
- Doppler echocardiography was used in 80 normotensive and 61 hypertensive subjects across normal-weight and obese categories.
- Left ventricular mass, dimensions, and filling parameters (isovolumic relaxation time, peak early transmitral flow velocity, deceleration time) were analyzed.
- Statistical models controlled for age, sex, blood pressure, and heart rate.
Main Results:
- Isovolumic relaxation time was prolonged in both hypertensive and obese normotensive subjects compared to normal-weight normotensive individuals.
- Left ventricular mass was higher in all groups compared to lean normotensive subjects.
- Obesity did not significantly worsen isovolumic relaxation time in hypertensive individuals.
- Differences in left ventricular filling parameters between groups were resolved after accounting for left ventricular mass.
Conclusions:
- Both arterial hypertension and obesity independently prolong isovolumic relaxation time.
- Left ventricular mass is a key factor mediating diastolic dysfunction in hypertension.
- Echocardiographic assessment of left ventricular geometry and function is vital in managing cardiovascular risk.
Abstract:
We assessed the relations of left ventricular filling to load and geometry by Doppler echocardiography in 80 normotensive subjects (40 normal-weight [36 +/- 12 years, 24 women] and 40 obese [35 +/- 13 years, 24 women]) and 61 hypertensive subjects without silent coronary heart disease (29 normal-weight [43 +/- 13 years, 15 women] and 32 obese [42 +/- 13 years, 19 women]) and comparable left ventricular midwall performance. Left ventricular mass divided by height to the 2.7 power was higher in all groups than in normotensive normal-weight subjects (all P < .0001) and in hypertensive than normotensive obese subjects (P < .001). After controlling for age, sex, blood pressure, and heart rate, isovolumic relaxation time was prolonged in hypertensive subjects and normotensive obese subjects compared with normotensive normal-weight subjects (all P < .0001). Body mass index, left ventricular dimension and mass, and circumferential end-systolic stress did not influence these differences. In pooled groups, prolonged isovolumic relaxation time was predicted by high mean blood pressure (beta = 0.52, P < .001), low end-systolic stress (beta = -0.33, P < .001), increased left ventricular mass (beta = 0.24, P < .004), and high body mass index (beta = 0.14, P < .05, multiple R = .72, SEE = 16.5 milliseconds, P < .0001). Between-group differences in peak early transmitral flow velocity, the deceleration time of early filling velocity, and the ratio of early to late left ventricular filling disappeared after controlling for left ventricular mass. Thus, (1) isovolumic relaxation time is prolonged in both arterial hypertension and obesity; (2) the presence of obesity does not significantly increase isovolumic relaxation time in hypertension; and (3) abnormalities of left ventricular filling in arterial hypertension are offset after controlling for left ventricular mass.