Heterogeneity of hemodynamic parameters in untreated primary hypertension, and individualization of antihypertensive therapy based on noninvasive hemodynamic measurements.

Noninvasive measurement of hemodynamic parameter was undertaken in 240 patients with untreated primary hypertension using impedance cardiography (ICG) in outpatient clinics. High output was defined as a cardiac index (CI) >3.6 L/minute/m(2) and high resistance was defined as the total peripheral resistance index (TPRI) >2700 dyne·s·m(2)/cm(5). Of all patients, 67% had high-resistance hypertension (high TPRI with normal or low CI), and 16% had high-output hypertension (high CI with normal TPRI). Treatment with β-blockers for high-output hypertension and with calcium channel blockers for high-resistance hypertension reduced blood pressure equally, and restored normal hemodynamic balance, as reported in studies using invasive monitoring methods. These findings suggest that it is appropriate to use noninvasive ICG measurements to guide antihypertensive therapy. Multivariate analysis showed that female gender, tachycardia, and low body mass index (BMI) were associated with high-output hypertension, but age was not. Heterogeneity of hemodynamic parameters is thought to be one of the reasons why the efficacies of antihypertensive agents differ between patients. It may be feasible to predict which antihypertensive agent would be the most effective for a particular patient based on hemodynamic measurements or combination of gender, heart rate, and BMI.