Cardiac Valves
The four cardiac valves open and close in a precisely timed sequence to maintain unidirectional blood flow. Their anatomical position, auscultation site, and common pathologies are examined in every clinical assessment.
✦ The Mnemonic
"Thoughtful Physicians Monitor Aortas"
Tricuspid · Pulmonary · Mitral · Aortic — right to left, venous to arterial
Clinical Breakdown
The atrioventricular valves (tricuspid and mitral) are supported by chordae tendineae attached to papillary muscles — preventing eversion during systole. The semilunar valves (pulmonary and aortic) are not attached to papillary muscles and rely on the pressure differential for closure. Aortic regurgitation occurs when the semilunar cusps fail to appose in diastole.
Aortic stenosis is the most common valvular disease in developed countries — typically calcific degeneration of a trileaflet (or bicuspid) valve in patients over 70. The classic triad: syncope, angina, breathlessness. Severity: severe when mean gradient >40 mmHg or valve area <1.0 cm². The aortic valve is the most commonly replaced valve surgically.
Mitral regurgitation can be acute (ruptured chordae/papillary muscle in MI, infective endocarditis) or chronic (rheumatic, myxomatous). Acute MR causes a sudden, severe haemodynamic collapse — the unprepared left atrium cannot accommodate the regurgitant volume, causing flash pulmonary oedema.
⭐ Clinical Pearl
Aortic auscultation areas do NOT correspond to anatomical valve positions — they represent where sounds are conducted. Aortic → 2nd ICS right sternal edge. Pulmonary → 2nd ICS left sternal edge. Tricuspid → 4th ICS left sternal edge. Mitral → apex (5th ICS MCL). Remember: All Patients Take Medicine (Aortic, Pulmonary, Tricuspid, Mitral — 2R, 2L, 4L, apex).