Pathophysiology
Clinical meaning
S1 (lub) results from closure of the mitral and tricuspid valves at the onset of systole. S2 (dub) results from closure of the aortic and pulmonic valves at the end of systole. Extra sounds (S3, S4, murmurs) indicate abnormal flow dynamics, valve dysfunction, or chamber compliance changes. Connect Heart Sounds to bedside cues you will reassess first: vitals trends, work of breathing, perfusion, mentation, and pain or ischemic equivalents when relevant. Boards reward recognizing when subtle instability outweighs reassurance, then selecting nursing actions that protect airway, circulation, and neurologic status before routine tasks.