Coronary Circulation Lecture Notes

Importance of Coronary Circulation

• Provides oxygenated blood to the myocardium, the muscle of the heart.
• Essential for heart function and systemic circulation.

Pathway of Blood in Coronary Circulation

• Begins in the left ventricle (systemic pump and coronary pump).
• Blood is pumped through the aortic semilunar valve into the ascending aorta.

Coronary Arteries

• Right and Left Coronary Arteries originate from the ascending aorta.
  • Occurs during diastole when heart relaxes, allowing blood into coronary circulation.

Right Coronary Artery

• Travels down the coronary sulcus.
• Branches:
  • Marginal Artery: Supplies the right ventricle and lateral side.
  • Posterior Interventricular Artery: Supplies the posterior heart.

Left Coronary Artery

• Branches:
  • Anterior Interventricular Artery (Left Anterior Descending Artery):
    • Supplies interventricular septum, left ventricle, and some of the right ventricle.
    • Known as "Widowmaker" due to high risk of occlusion leading to myocardial infarction.
  • Circumflex Artery:
    • Wraps around the left auricle.
    • Supplies the left atrium and ventricle.

Artery to Capillary Pathway

• Arteries → Arterioles → Capillaries (in myocardium for blood exchange)

Venous Drainage

• Venules collect deoxygenated blood from myocardium.
• Veins:
  • Small Cardiac Vein: Drains blood supplied by marginal artery.
  • Middle Cardiac Vein: Drains blood from the posterior interventricular artery.
  • Great Cardiac Vein: Drains blood from anterior interventricular artery.
  • Posterior Vein of Left Ventricle: Drains blood from circumflex artery area.

Coronary Sinus

• All veins empty into the Coronary Sinus, a large vein.
• Coronary Sinus empties into the right atrium.
  • From right atrium, blood moves to the right ventricle and then to pulmonary circulation for re-oxygenation.

Key Points

• Myocardium receives blood only during diastole.
• High heart rates reduce diastole duration, potentially affecting myocardial oxygen supply.

Conclusion

• Understanding this pathway is crucial for comprehending heart functionality and potential coronary diseases.

• Note: Review accompanying diagrams for a visual understanding.