Systolic Murmurs
Systolic murmurs occur between S1 and S2. The four major systolic murmurs: (1) Aortic Stenosis — harsh crescendo-decrescendo at RUSB, radiates to carotids, associated with slow-rising pulse and narrow pulse pressure; most common valvular disease in adults >65. (2) Pulmonic Stenosis — similar but at LUSB, increases with inspiration (Carvallo's sign). (3) Mitral Regurgitation — holosystolic at apex, radiates to axilla; causes include MVP, rheumatic heart disease, papillary muscle rupture (inferior MI). (4) Tricuspid Regurgitation — holosystolic at LLSB, increases with inspiration; causes include IV drug use endocarditis, RV dilation.
Diastolic Murmurs
Diastolic murmurs always indicate pathology. (1) Aortic Regurgitation — high-pitched blowing decrescendo at LUSB, best heard leaning forward in expiration; widened pulse pressure, bounding (Corrigan's) pulse, Austin Flint murmur (low-pitched mid-diastolic from AR jet). (2) Mitral Stenosis — low-pitched rumbling at apex, best with bell in left lateral decubitus; opening snap (OS) follows S2 — shorter S2-OS interval = more severe stenosis; associated with rheumatic fever. (3) Pulmonic Regurgitation — rare, Graham Steell murmur in pulmonary hypertension.
Dynamic Auscultation Maneuvers
Maneuvers change preload and afterload to identify murmurs: Valsalva (phase 2) — decreases preload → most murmurs soften; exceptions: HOCM and MVP get louder (less volume = more obstruction/prolapse). Squatting — increases preload + afterload → most murmurs louder; HOCM and MVP soften. Standing from squat — decreases preload → HOCM and MVP louder again. Handgrip — increases afterload → softens HOCM and AS; loudens AR and MR. Inspiration — right-sided murmurs louder (more venous return to RV); Carvallo's sign for TR/PS.
MVP vs HOCM
Both behave similarly with maneuvers (louder with decreased preload) but have distinct features: MVP (Mitral Valve Prolapse) — mid-systolic click followed by late systolic murmur at apex; more common in young women; Marfan and Ehlers-Danlos association; click moves earlier with decreased preload (Valsalva/standing). HOCM (Hypertrophic Obstructive Cardiomyopathy) — harsh systolic murmur at LLSB without radiation to carotids (distinguishes from AS); asymmetric septal hypertrophy on echo; risk of sudden cardiac death in young athletes; treat with beta-blockers or disopyramide; avoid digoxin, vasodilators, and diuretics.
Innocent vs Pathologic Murmurs
Innocent murmurs: systolic only, grade ≤2/6, no radiation, no associated symptoms, normal S2 splitting. Still's murmur is the most common innocent murmur in children — musical/vibratory quality at LLSB. All diastolic murmurs, continuous murmurs (except venous hum in children), holosystolic murmurs, and grade ≥3 murmurs are pathologic until proven otherwise.