Narrowed Aortoseptal Angle Is Related to Increased Central Blood Pressure and Aortic Pressure Wave Reflection

Abstract

The left ventricular (LV) aortoseptal angle (ASA) decreases with age, and is associated with basal septal hypertrophy (septal bulge). Enhanced arterial pressure wave reflection is known to impact LV hypertrophy. We assessed whether ASA is related to central blood pressure (BP) and augmentation index (AI), a measure of the reflected pressure wave. We studied 75 subjects (age 62 ± 16 years; 66% female) who were referred for transthoracic echocardiography and had radial artery applanation tonometry within 24 h. Peripheral systolic BP (P-SBP), peripheral diastolic BP (P-DBP), and peripheral pulse pressure (P-PP) were obtained by sphygmomanometry. Central BPs (C-SBP, C-DBP, C-PP) and AI were derived from applanation tonometry. AI was corrected for heart rate (AI75). The basal septal wall thickness (SWT), mid SWT and ASA were measured using the parasternal long axis echocardiographic view. Mean ASA and AI75 were 117 ± 11° and 22 ± 11%, respectively. ASA correlated with AI75 (r = –0.31, p ≤ 0.01), C-SBP (r = –0.24, p = 0.04), C-PP (r = –0.29, p = 0.01), but only showed a trend towards significance with P-SBP (r = –0.2, p = 0.09) and P-PP (r = –0.21, p = 0.08). Interestingly, C-PP was correlated with basal SWT (r = 0.27, p = 0.02) but not with mid SWT (r = 0.19, p = 0.11). On multivariate linear regression analysis, adjusted for age, gender, weight, and mean arterial pressure, AI75 was an independent predictor of ASA (p = 0.02). Our results suggest that a narrowed ASA is related to increased pressure wave reflection and higher central BP. Further studies are needed to determine whether narrowed LV ASA is a cause or consequence of enhanced wave reflection and whether other factors are involved.