Noninvasive hemodynamic profiles in hypertensive subjects

Abstract

Hypertension is a disease state characterized by increased blood pressure (BP) associated with hemodynamic abnormalities, including elevated systemic vascular resistance index (SVRI); and altered cardiac index (CI). The objective of this study was to use noninvasive impedance cardiography (ICG) to evaluate hemodynamic characteristics of subjects with and without hypertension. A total of 19 healthy nonhypertensive and 136 hypertensive subjects were retrospectively evaluated. Hemodynamic parameters were measured with ICG and included CI, SVRI, total arterial compliance index (TACI), and thoracic fluid content (TFC); these were compared with subject type, blood pressure value, demographics, and medications. The BP levels of healthy and hypertensive subjects were 117/71 and 154/90 mm Hg, respectively (P < .0001). Subjects with prehypertension had a lower TACI (0.97 v 1.21, P < .05) compared with those with a normal BP, ie, <120/80 mm Hg. Hypertensive subjects had significantly lower SI, CI, TACI, and TFC and significantly higher SVRI. Subjects with stage 2 hypertension had higher SVRI (4149 v 3418 dyne.sec(2).cm(-5).m(2), P < .01) and lower TACI (0.61 v 0.53 mm Hg/mL/m(2), P < .05) than those with stage 1 hypertension. Compared with subjects with controlled hypertension, normal subjects had significantly lower SVRI (1996 v 2746 dyne.sec(2).cm(-5).m(2), P < .0001) and significantly higher CI (3.23 v 2.63 L/min/m(2), P < .001), SI (48.2 v 37.4 mL/m(2), P < .0001), TACI (1.08 v 0.85 mm Hg/mL/m(2), P < .01), and TFC (29.1 v 24.1/kOhm, P < .0001). The parameters of TACI, SVRI, and CI demonstrated modest correlation (-0.75, 0.62, and -0.30), respectively, with SBP. In the 54 subjects with BP <140/90 mm Hg, SVRI values varied significantly, with 32 subjects (39.2%) with SVRI values in the high range (>2483 dyne.sec(2).cm(-5).m(2)). Hemodynamic parameters from ICG displayed significantly different hemodynamic profiles between hypertensive and nonhypertensive subjects. However, significant individual variation of hemodynamic status exists. Hemodynamic measurements with ICG characterize hemodynamic status and may be helpful in diagnostic, prognostic, and therapeutic decision making in hypertensive subjects.