heart murmur

Heart murmurs result from turbulent blood flow, which can occur due to increased flow velocity, flow across a narrowed/stenotic valve, flow through an abnormal opening (e.g., VSD), regurgitant flow through an incompetent valve, or flow into a dilated chamber. Murmurs are classified by timing (systolic vs diastolic), shape, location, radiation, intensity (graded 1-6), pitch, and quality. Systolic murmurs include: aortic stenosis (crescendo-decrescendo, radiates to carotids), mitral regurgitation (holosystolic, radiates to axilla), mitral valve prolapse (mid-systolic click followed by murmur), VSD (holosystolic, harsh), and hypertrophic cardiomyopathy (increases with Valsalva/standing, decreases with squatting). Diastolic murmurs include aortic regurgitation (early diastolic, decrescendo) and mitral stenosis (mid-diastolic rumble with opening snap). Continuous murmurs occur in PDA (machine-like). Dynamic auscultation maneuvers help differentiate murmurs: Valsalva and standing decrease preload (accentuates HCM, MVP); squatting and leg raise increase preload/afterload (accentuates AS, MR, VSD); handgrip increases afterload (accentuates MR, AS softer, VSD). Innocent murmurs (e.g., Still's murmur) are common in children, are typically soft, early systolic, and vary with position, without associated symptoms. Pathologic murmurs warrant echocardiography for definitive diagnosis. Associated symptoms (syncope, dyspnea, chest pain) or signs (thrill, S3/S4, cyanosis) suggest structural heart disease requiring further workup. Key exam-style associations: aortic stenosis-syncope/angina/CHF triad; mitral regurgitation-in acute MI (papillary muscle rupture); mitral stenosis-history of rheumatic fever, atrial fibrillation; PDA-maternal rubella infection.