Valvular aortic stenosis with concentric hypertrophy elevates diastolic filling pressures due to increased muscle mass and, in a subset of patients, augmented muscle stiffness.
Observational (n=17)
What are the determinants of elevated diastolic pressures and ventricular stiffness in patients with valvular aortic stenosis and left ventricular hypertrophy?
Elevated diastolic filling pressures in aortic stenosis are driven by both concentric hypertrophy and, in a subset of patients, augmented but potentially reversible myocardial stiffness.
Left ventricular (LV) chamber and myocardial stiffness were determined in 17 patients, four subjects with normal LV function and 13 subjects with valvular aortic stenosis and concentric myocardial hypertrophy, using simultaneous catheter micromanometry and LV cineangiography. Pressure (P), volume (V), and wall thickness (h) were measured. Variability in both chamber and myocardial stiffness parameters was found with five of the aortic stenosis patients (Group 1, left ventricular end-diastolic pressure = 15 +/- 2 (SEM) mm Hg) exhibiting normal values for end-diastolic dP/dV and dP/dV/V, for chamber stiffness constants (a,a') derived from P-V and normalized P-V relations, respectively, for end-diastolic myocardial elastic stiffness (ES or EE, where S = spherical model and E = ellipsoidal model) at the midwall of the minor axis circumference, and for the myocardial stiffness constants (KS or KE) of the circumferential stress-strain relation. Eight other patients with aortic stenosis (Group II, left ventricular end-diastolic pressure = 20 +/- 3 (SEM) mm Hg) exhibited significant increases in end-diastolic dP/dV,dP/dV/V,ES and EE and a tendency for increase in the chamber stiffness constants (a,a') and myocardial stiffness constants (KS, KE). These observations suggest that concentric increase in muscle mass (increase in wall thickness/minor axis radius ratio and wall volume/chamber volume ratio) is an important determinant of elevated mid- and late diastolic pressures in patients with valvular aortic stenosis, while concurrently mitigating increases in both systolic and diastolic wall stress. In some patients with aortic stenosis, however, diastolic filling pressures are elevated more severely, not only as a result of concentric hypertrophy, but also in response to augmented muscle stiffness. Reversibility of increased ventricular diastolic stiffness and elevated filling pressures was documented as concentric hypertrophy regressed post-aortic valve replacement in one patient, suggesting that fibrosis is not invariably the cause of enhanced myocardial stiffness in this secondary and compensatory form of hypertrophy.
Peterson et al. (Sat,) conducted a observational in Valvular aortic stenosis and left ventricular hypertrophy (n=17). Valvular aortic stenosis and concentric myocardial hypertrophy vs. Normal LV function was evaluated on Left ventricular chamber and myocardial stiffness. Valvular aortic stenosis with concentric hypertrophy elevates diastolic filling pressures due to increased muscle mass and, in a subset of patients, augmented muscle stiffness.