Coronary Circulation
1. Introduction
Coronary circulation refers to the blood supply of the heart muscle (myocardium).
The heart, though filled with blood, requires its own vascular supply due to the thickness
of the myocardium.
It is essential for delivering oxygen and nutrients and removing metabolic wastes.
It forms the functional blood supply of the heart, accounting for ~4–5% of cardiac
output.
2. Coronary Arteries
Two main coronary arteries arise from the ascending aorta, just above the aortic valve:
o Right Coronary Artery (RCA)
o Left Coronary Artery (LCA)
Right Coronary Artery (RCA):
Originates from the right aortic sinus.
Supplies:
o Right atrium
o Most of the right ventricle
o Inferior part of the left ventricle
o Posterior 1/3rd of interventricular septum
, o Sinoatrial (SA) node in 60% cases
o Atrioventricular (AV) node in 85% cases
Left Coronary Artery (LCA):
Originates from the left aortic sinus.
Divides into:
o Left Anterior Descending (LAD) artery – supplies:
Anterior wall of left ventricle
Anterior 2/3rd of interventricular septum
o Left Circumflex (LCx) artery – supplies:
Lateral and posterior walls of the left ventricle
Left atrium
Coronary Artery Dominance:
Determined by which artery gives rise to the posterior descending artery (PDA):
o Right-dominant: PDA from RCA (~55% cases)
o Left-dominant: PDA from LCx (~18% cases)
o Co-dominant: PDA from both (~27% cases)
3. Venous Drainage
Three major routes:
1. Coronary Sinus (main drainage, ~75% of total flow) → Right atrium
2. Anterior Cardiac Veins → Drain directly into the right atrium
3. Thebesian Veins → Open into all chambers (mainly right); contribute to
physiological shunt
4. Physiological Shunt
Thebesian veins and bronchial veins introduce deoxygenated blood into arterial
circulation.
Causes a slight reduction in arterial oxygen saturation (~97–98%), never 100%.
Called a right-to-left physiological shunt.
5. Coronary Blood Flow (CBF)
Normal flow: ~200 mL/min or 70–80 mL/min/100 g of tissue.
Accounts for ~4% of total cardiac output.
1. Introduction
Coronary circulation refers to the blood supply of the heart muscle (myocardium).
The heart, though filled with blood, requires its own vascular supply due to the thickness
of the myocardium.
It is essential for delivering oxygen and nutrients and removing metabolic wastes.
It forms the functional blood supply of the heart, accounting for ~4–5% of cardiac
output.
2. Coronary Arteries
Two main coronary arteries arise from the ascending aorta, just above the aortic valve:
o Right Coronary Artery (RCA)
o Left Coronary Artery (LCA)
Right Coronary Artery (RCA):
Originates from the right aortic sinus.
Supplies:
o Right atrium
o Most of the right ventricle
o Inferior part of the left ventricle
o Posterior 1/3rd of interventricular septum
, o Sinoatrial (SA) node in 60% cases
o Atrioventricular (AV) node in 85% cases
Left Coronary Artery (LCA):
Originates from the left aortic sinus.
Divides into:
o Left Anterior Descending (LAD) artery – supplies:
Anterior wall of left ventricle
Anterior 2/3rd of interventricular septum
o Left Circumflex (LCx) artery – supplies:
Lateral and posterior walls of the left ventricle
Left atrium
Coronary Artery Dominance:
Determined by which artery gives rise to the posterior descending artery (PDA):
o Right-dominant: PDA from RCA (~55% cases)
o Left-dominant: PDA from LCx (~18% cases)
o Co-dominant: PDA from both (~27% cases)
3. Venous Drainage
Three major routes:
1. Coronary Sinus (main drainage, ~75% of total flow) → Right atrium
2. Anterior Cardiac Veins → Drain directly into the right atrium
3. Thebesian Veins → Open into all chambers (mainly right); contribute to
physiological shunt
4. Physiological Shunt
Thebesian veins and bronchial veins introduce deoxygenated blood into arterial
circulation.
Causes a slight reduction in arterial oxygen saturation (~97–98%), never 100%.
Called a right-to-left physiological shunt.
5. Coronary Blood Flow (CBF)
Normal flow: ~200 mL/min or 70–80 mL/min/100 g of tissue.
Accounts for ~4% of total cardiac output.
