Mathematical model analysis of heart-arterial interaction in hypertension

We studied heart-arterial interaction in hypertension-induced left ventricular hypertrophy (LVH) using a LV time-varying elastance model coupled to a 4-element lumped parameter model of the systemic arterial system. After assessing cardiac and arterial model parameters for normotensive control subjects, we applied arterial changes as observed in hypertensive patients with LVH (resistance +40%; compliance -25%) and assumed (i) no cardiac adaptation; (ii) LVH normalizes systolic wall stress (σ_s); (iii) LVH normalizes σ_s and venous filling pressure (P_v) increases such that end-diastolic wall stress (σ_d) is normalized as well. Human in vivo data show that in hypertensives with LVH, systolic and diastolic blood pressure increase by about 40% while cardiac output is constant and wall thickness increases by 30-55%. In both (i) and (ii), blood pressure increased by only 10% while cardiac output dropped by 20%. In (ii), LV wall thickness increased by only 10%. In contrast, the predictions of (iii) were in qualitative and quantitative agreement with in-vivo human data. We conclude that besides an increase in LV mass and wall thickness, normalizing σ_s, cardiac adaptations further consist of an increase in P_v, normalizing σ_d and preserving cardiac output in the presence of an impaired diastolic function.