Heart Valves – Core Review

Heart Valve Basics

  • Human heart contains 4 primary valves: Tricuspid, Pulmonary (semilunar), Mitral (=) Bicuspid, Aortic (semilunar)

  • Purpose: ensure unidirectional blood flow, open/close in response to pressure changes

Anatomical Locations & Flow Sequence

  • Right atrium → Tricuspid valve → Right ventricle → Pulmonary semilunar valve → Pulmonary artery

  • Left atrium → Mitral (Bicuspid) valve → Left ventricle → Aortic semilunar valve → Aorta

  • Mnemonic for flow order: “Try Pull My Aorta” (Tricuspid → Pulmonary → Mitral → Aortic)

Structural Support Elements

  • Valves anchored by fibrous rings (annuli) within cardiac skeleton

  • Atrioventricular valves have chordae tendineae attached to papillary muscles to prevent prolapse

  • Semilunar valves lack chordae; rely on pocket-like cusps to seal

Cross-Sectional Orientation Highlights

  • Interventricular septum divides right & left ventricles

  • Mitral and Aortic valves lie close together; Tricuspid slightly anterior; Pulmonary most superior

  • Coronary arteries originate just above Aortic valve cusps

Common Pathologies

  • Stenosis: narrowing, ↑ pressure gradient

  • Regurgitation (insufficiency): back-flow e.g., mitral regurgitation

  • Congenital defects: bicuspid aortic valve, septal tears

Surgical Repair / Replacement

  • Goals: restore competency, relieve obstruction, preserve ventricular function

  • Repair (e.g., patching aortic tear) preferred when feasible

  • Replacement indicated for severe damage or calcification

Artificial Heart Valves

  • Two main categories:
    • Mechanical valves (e.g., metal “ball-and-cage”) – durable, lifelong anticoagulation required
    • Tissue valves (bovine, porcine, homograft) – lower thrombosis risk, limited lifespan

  • Prostheses are sized and sutured (or clipped) into native annulus

Historic Breakthrough: Magovern-Cromie Sutureless Valve (early 1960s)

  • Rapid implantation minimized cardioplegic time

  • Mortality dropped from 90\% to 10\% (i.e., 90\% survival)

  • Oldest documented functioning artificial valve still observed in a patient

Quick Recall Points

  • Total squeezes per minute ≈ resting heart rate: \approx 70\,\text{beats\/min}

  • Atrioventricular = Tricuspid & Mitral; Semilunar = Pulmonary & Aortic

  • Papillary muscles contract with ventricles, maintaining leaflet closure

  • Radiographic / surgical views: “side view” highlights A-V valves alignment; “top view” shows coronary artery origins