At this point there may be signs of ventricular strain pattern (ST segment depression and T wave inversion) on the EKG, suggesting subendocardial ischemia. The subendocardium is the region that is most susceptible to ischemia because it is the most distant from the epicardial coronary arteries. Syncope
Syncope (fainting spells) from aortic valve stenosis is usually exertional. In the setting of heart failure it increases the risk of death. In people with syncope, the three-year mortality rate is 50% if the aortic valve is not replaced.It is unclear why aortic stenosis causes syncope. One theory is that severe AS produces a nearly fixed cardiac output. When a person with aortic stenosis exercises, their peripheral vascular resistance will decrease as the blood vessels of the skeletal muscles dilate to allow the muscles to receive more blood to allow them to do more work. This decrease in peripheral vascular resistance is normally compensated for by an increase in the cardiac output. Since people with severe AS cannot increase their cardiac output, the blood pressure falls and the person will faint due to decreased blood perfusion to the brain.A second theory is that during exercise the high pressures generated in the hypertrophied left ventricle cause a vasodepressor response, which causes a secondary peripheral vasodilation that, in turn, causes decreased blood flow to the brain resulting in loss of consciousness.
In a similar manner, there may be a delay between the appearance of each pulse in the brachial artery (in the arm) and the radial artery (in the wrist). Auscultation
The first heart sound may be followed by a sharp ejection sound ("ejection click") best heard at the lower left sternal border and the apex, and, thus, appear to be "split". The ejection sound, caused by the impact of left ventricular outflow against the partially fused aortic valve leaflets, is more commonly associated with a mobile bicuspid aortic valve than an immobile calcified aortic valve. The intensity of this sound does not vary with respiration, which helps distinguish it from the ejection click produced by a stenotic pulmonary valve, which will diminish slightly in intensity during inspiration.An easily heard systolic, crescendo-decrescendo (i.e., ejection) murmur is heard loudest at the upper right sternal border, at the 2nd right intercostal space, and radiates to the carotid arteries bilaterally. The murmur increases with squatting and decreases with standing and isometric muscular contraction such as the Valsalva maneuver, which helps distinguish it from hypertrophic obstructive cardiomyopathy (HOCM). The murmur is louder during expiration but is also easily heard during inspiration. The more severe the degree of the stenosis, the later the peak occurs in the crescendo-decrescendo of the murmur.The second heart sound (A2) tends to become decreased and softer as the aortic stenosis becomes more severe. This is a result of the increasing calcification of the valve preventing it from "snapping" shut and producing a sharp, loud sound.