Arterial Supply and Venous Drainage of the Heart

Coronary Arteries

• Origin: Coronary arteries arise from the ascending aorta above the aortic valve.
• Location: They run on the heart's surface within subpericardial fibrofatty tissue.
• Anatomical vs. Functional: Anatomically not end arteries, but functionally behave like end arteries.

Right Coronary Artery (RCA)

• Origin: Arises from the anterior aortic sinus of the ascending aorta.
• Course:
  • Moves between the pulmonary trunk and right auricle.
  • Descends into the right atrioventricular groove.
  • Turns posteriorly at the heart's inferior border and runs in the posterior atrioventricular groove.
  • Terminates by anastomosing with the left coronary artery.
• Branches and Distribution:
  • Right Conus Artery: Supplies anterior pulmonary conus.
  • Anterior Ventricular Branches: Supply anterior right ventricle.
  • Marginal Branch: Largest, reaches the heart's apex.
  • Atrial Branches: Supply atria; SA node in 60% of cases.
  • Posterior Ventricular Branches: Supply diaphragmatic surface of ventricles.
  • Posterior Interventricular Artery: Supplies interventricular septum, AV node in 60% cases.

Left Coronary Artery (LCA)

• Origin: Arises from the left posterior aortic sinus of the ascending aorta.
• Course:
  • Runs forward and left between the pulmonary trunk and left auricle.
  • Divides into anterior interventricular artery (LAD) and circumflex artery.
• Branches and Distribution:
  • Anterior Interventricular Artery (LAD): Supplies interventricular septum, major part of left ventricle, part of right ventricle.
  • Circumflex Artery: Winds around left heart margin, anastomoses with RCA.
  • Left Marginal Artery: Supplies left ventricle margin.
  • Diagonal and Conus Arteries: Supply additional areas including pulmonary conus and left atrium.

Clinical Correlations

• Angina Pectoris:
  • Caused by narrowed coronary arteries reducing blood supply.
  • Pain on exertion, relieved by rest.
  • Referred pain to left shoulder, arm, and forearm.
• Myocardial Infarction:
  • Caused by sudden blockage of coronary arteries.
  • Symptoms include chest pressure, nausea, sweating, short breath, tachycardia.
  • Common occlusion sites: LAD (40-50%), RCA (30-40%), Circumflex (15-20%).
  • Infarction mostly occurs at rest.

Venous Drainage of the Heart

• Coronary Sinus:
  • Principal heart vein, drains into right atrium.
  • Largest vein, located in the posterior atrioventricular groove.
  • Formed from the left horn of sinus venosus and part of left common cardinal vein.
• Tributaries:
  • Great Cardiac Vein: Accompanies LAD and circumflex arteries.
  • Middle Cardiac Vein: Accompanies posterior interventricular artery.
  • Small Cardiac Vein: Accompanies right ventricular artery.
  • Posterior Vein of the Left Ventricle: Joins the sinus to middle cardiac vein.
  • Oblique Vein of Left Atrium: Small vein on left atrium, entering coronary sinus.
• Other Veins:
  • Anterior Cardiac Veins: Open directly into right atrium.
  • Vena Cordis Minimae: Small veins in all heart chambers.