Association between wasted pressure effort and left ventricular hypertrophy in hypertension: Influence of arterial wave reflection

Abstract

Background: Wave reflection during the systole increases left ventricular (LV) pressure, tension-time index (TTI) and myocardial oxygen requirement. The purpose of this study was to extract that component of extra myocardial oxygen requirement that is due to early systolic wave reflection, define it as wasted effort (ΔEw), and examine its relationship to LV hypertrophy (LVH). Methods: Radial artery pressure waveforms were recorded using applanation tonometry and central aortic waveforms generated in 98 patients with untreated hypertension. Aortic augmentation index (AIa), wave reflection amplitude (i.e., aortic augmented pressure (AG)) and systolic duration (ED-Tr), ejection duration (ED) and round-trip travel time of the pressure wave (Tr) were calculated from the aortic waveform, and ΔEw estimated as 2.09 AG (ED-Tr). Carotid-femoral pulse wave velocity (PWVe) was also measured and LV mass index (LVMI) determined by echocardiography. Results: ΔEw was significantly correlated with age, body height, and LVMI. Women had greater ΔEw than men. The correlation between ΔEw and LVMI was independent of age, gender and body height (P = 0.003). Patients with LVH (LVH (+) group) showed greater ΔEw than patients without LVH (LVH (-) group) (P = 0.003), and this difference remained significant when adjusted for confounding factors. Also, AIa and AG were higher in the LVH (+) than in the LVH (-) group (both P < 0.01). In contrast, PWVe was not different between the groups, and Tr showed only a marginal difference (P = 0.07). Conclusions: ΔEw appears to be directly and positively associated with LVH in untreated hypertensive patients. The amplitude and duration of the reflected wave, rather than its travel time, are probably responsible for this association. © 2008 American Journal of Hypertension, Ltd.