9. Reversed Paradoxical Split of the Second Sound - Heart Sounds Collection #CCU_SOUND Paradoxical Split S2 A paradoxical split S2 heart sound occurs when the splitting is heard during expiration and disappears during inspiration — opposite of the physiologic split S2. A paradoxical split S2 occurs in any setting that delays the closure of the aortic valve including severe aortic stenosis and hypertrophic obstructive cardiomyopathy, or in the presence of a left bundle branch block. CLINICAL PEAR