Office blood pressures, arterial compliance characteristics, and estimated cardiac load

Because of rising interest in new methods to detect arterial diseases, we compared data from 3 different compliance-related techniques to measure arterial stiffness: systolic pulse contour analysis, diastolic pulse contour analysis (modified Windkessel model), and muscular (brachial) artery compliance by cuff plethysmography. Variables measured in the sitting position were compared with each other, with clinic blood pressures (BPs), and with the cardiac time-tension integral (CTTI) in 63 established hypertensive and 28 age-matched normotensive subjects. Hypertensives demonstrated marginal reductions in C₁ (thought to represent reduced large vessel compliance) and increased central systolic BP augmentation. In contrast, muscular artery compliance tended to be greater in the hypertensives despite normal brachial arterial diameters. C₂, suggested to be an indicator of small artery properties, was similar in both groups. CTTI was strongly related to systolic pressure (r=0.81), integrated mean arterial pressure (r=0.83), and systolic pressure-heart rate product (r=0.85) and was less strongly related to diastolic (r=0.71) or pulse pressure (r=0.57). Weak correlations were observed between CTTI and measured compliance-related variables, which also showed absent or weak correlations among themselves. We conclude that the weak relationships among BP and compliance-related variables could be due to intrinsic differences in the properties of large and small arteries, theoretical methodological weaknesses, measurement artifacts, or intrinsic hemodynamic differences of the sitting position. At present, compliance-related variables provide little additional advantage over cuff BP in the office estimation of cardiac work.