Fig 1.
Central illustration demonstrating the complex relationship between systolic blood pressure and mean transvalvular gradients.
For a given AVA, the impact of hypertension on MG is mediated through a change in mean flow rate (MFR). The magnitude of this impact is modulated by the LV elastance. Subsequently, the magnitude of MFR induced changes in MG is modulated by the combined energy loss coefficient. AVA–aortic valve area, LV–left ventricle. * Other factors that influences the MFR and the vulnerability to blood pressure induced changes in MFR include preload (left ventricular end diastolic volume); and the end-systolic activation time of the ventricles, systemic arterial compliance, and right ventricular unstressed volume.
Fig 2.
Zero—dimensional electro-hydraulic analogue model of human cardiovascular system.
(R–resistance; L–inductance; C–capacitance; LA–left atrium; MI–mitral valve; LV–left ventricle; AO–aortic valve; RA–right atrium; TI–tricuspid valve; RV–right ventricle; PO–pulmonary valve).
Fig 3.
Mean flow rate (ml/s) response behavior over a range of systolic arterial blood pressures (mmHg) for various aortic valve area’s (AVA) and various LV elastances (E).
Table 1.
Baseline experiment findings.
Fig 4.
Mean aortic transvalvular gradient (mmHg) (Y-axis) over a range of mean flow rate (ml/s) (X–axis).
Fig 5.
Mean aortic transvalvular gradient (mmHg) over a range of mean flow rate (ml/s) for an aortic valve area (AVA) of 0.8cm2, a constant hydraulic valve orifice area (Dh) of 2.4cm and a κ–value (energy loss coefficient) as determined by a sinus diameter (Dsinus) of 25mm, 30mm and 35mm respectively.
Fig 6.
a: A typical rheumatic aortic stenosis valve orifice morphology vs a degenerative aortic stenosis valve orifice morphology. Both valves have similar ‘hemodynamic orifice areas’, however, because of significant differences in perimeter, the ‘hydraulic orifice’ areas will be noticeably different. b: Mean transvalvular gradient–mean transvalvular flow rate relationship for a hemodynamic aortic valve area of 0.8cm2, a sinus diameter of 30mm but with a K (energy loss coefficient) as determined by a typical rheumatic aortic valve morphology vs a degenerative aortic valve morphology (MG–mean transvalvular gradient; MFR–mean transvalvular flow rate).