Ventricular-vascular stiffening in patients with repaired coarctation of aorta: integrated pathophysiology of hypertension

Abstract

Background: Despite successful repair, patients with coarctation of the aorta (COA) often show persistent hypertension at rest and/or during exercise. Previous studies indicated that the hypertension is mainly due to abnormalities in the arterial bed and its regulatory systems. We hypothesized that ventricular systolic stiffness also contributes to the hypertensive state in these patients in addition to increased vascular stiffness.

Methods and results: The study involved 43 patients with successfully repaired COA and 45 age-matched control subjects. Ventricular systolic stiffness (end systolic elastance) and arterial stiffness (effective arterial elastance) were measured invasively by ventricular pressure-area relationship during varying preload before and after beta-adrenergic stimulation. The mean systolic blood pressure was significantly higher with concomitant increases in both end systolic elastance and effective arterial elastance in patients with COA compared with control subjects (113.2+/-16.8 versus 91.0+/-9.1 mm Hg, 44.5+/-17.0 versus 19.2+/-6.7 mm Hg/mL/m(2), and 27.8+/-11.4 versus 20.2+/-4.8 mm Hg/mL/m(2), respectively; P<0.01 for each). End systolic elastance and effective arterial elastance of patients with COA showed exaggerated responses to beta-adrenergic stimulation, further amplifying blood pressure elevation. Quantification analyses assuming that ventricular systolic stiffness of patients with COA is equal to that of the control revealed that ventricular systolic stiffness accounts for approximately 50% to 70% of the elevated blood pressure in patients with COA. Furthermore, combined ventricular-arterial stiffening amplified systolic pressure sensitivity to increased preload during abdominal compression and limited stroke volume gain/relaxation improvement induced by beta-adrenergic stimulation.

Conclusions: Increased ventricular systolic stiffness, coupled with increased arterial stiffness, plays important roles in hypertension in patients with repaired COA. Thus, ventricular systolic stiffness is a potentially suitable target for reduction of blood pressure and improvement of prognosis of patients with COA.