The left ventricle thickness is a limiting factor of optimal heart size and strength. Due to disappearance of all the features compromising left ventricular compliance, mammalian heart has decreased vascular density and coronary vessel diameter and it requires sufficient diastolic aortic pressure for the left ventricle perfusion. Atrial muscle and the right ventricle are perfused during the entire heart cycle. The systolic pressure in the left ventricle forces blood vessels in the muscle wall to collapse, particularly in the subendocardial muscle layer. This makes the most active part of the heart prone to hypoxia. Optimal perfusion of the left ventricle wall requires sufficient aortic pressure during diastole, making individuals with higher diastolic pressures advantageous, in situations requiring combination of increased heart rate and output. Described mechanisms might have contributed to the hereditary quality of age-related hypertension in humans.