Coronary Microcirculation in Aortic Stenosis: Pathophysiology, Invasive Assessment, and Future Directions

Figure 4

Transmural impact of aortic stenosis with coronary disease: reduced flow from aortic stenosis and coronary stenosis does not affect all layers of the myocardium equally. Under baseline conditions, autoregulation (“auto” subscript) maintains a relatively stable flow for most perfusion pressures. Vasodilation (“max” subscript) produces the net hyperemic myocardial load line from Figure 3 that is made up of a lower offset in the subepicardium (Epi) than the subendocardium (Endo), with potentially different slopes as well. Exercise reduces diastolic perfusion time and increases left ventricular pressures, preferentially affecting the subendocardium both through tachycardia and also increased oxygen consumption. The resulting hypoperfusion can produce the classic symptoms of valvular stenosis.