Lesson 14: Coronary Circulation

Lesson 14: Coronary Circulation Overview

  • Coronary Artery Origins: Left and right coronary arteries (LCA and RCA) arise from the aortic root.

Coronary Arteries

  • LCA: Divides into left anterior descending (LAD) and circumflex arteries.

    • LAD: Supplies anterolateral and apical walls of left ventricle, anterior two-thirds of interventricular septum (EKG leads V1-V4).

    • Circumflex: Supplies left atrium, lateral and posterior walls of left ventricle (EKG leads I, aVL, V5-V6).

  • RCA: Supplies right atrium, right ventricle, interatrial septum, and posterior third of interventricular septum (EKG leads II, III, aVF).

  • Posterior Descending Artery (PDA): Supplies inferior wall, defines coronary dominance (usually arises from RCA in 70-80% of patients).

Coronary Venous Circulation

  • Main Veins:

    1. Great cardiac vein (associated with LAD)

    2. Middle cardiac vein (associated with PDA)

    3. Anterior cardiac vein (associated with RCA)

    4. Coronary Sinus: Most blood returns here, located on posterior right atrium.

  • Thebesian Veins: Drain into all cardiac chambers, contributing to small anatomical shunt.

Ischemia Assessment

  • Epicardial Vessels: RCA, LAD, and CxA; subject to vascular stenosis due to atherosclerosis.

  • Collateral Circulation: Provides redundancy of blood flow; risk if occlusion occurs proximal to collateral branches.

  • Key Areas of Supply and EKG Leads:

    • Septum: LAD (Bipolar leads)

    • Inferior Region: RCA (aVF leads).

Echocardiography

  • Myocardial Ischemia Diagnosis: Best view is midpapillary muscle level in short-axis; second best is apical segment in short-axis.