What is Cardiac Perfusion?  and Coronary Circulation?

Overview:

• The heart is a working muscle that requires its own constant blood supply (coronary arteries, capillaries, and veins) to meet its oxygen and nutrient needs.
• The blood vessels (coronary arteries) responsible for this perfusion (flow of blood) originate from the base of the aorta.

Coronary Arteries:

• Right coronary artery (RCA):
  • Mainly supplies the right side of the heart.
  • Feeds the SA node in over 50% of the population.
• Left coronary artery (LCA):
  • Supplies the left side, including the left ventricle.
  • Critical for cardiac output, as the left ventricle pumps oxygen-rich blood to the body.

Blood Flow Dynamics:

• Blood flow is greatest during diastole (relaxation phase):
  • Heart’s chambers are relaxed, vessels are less compressed.
  • During systole (contraction), coronary vessels narrow, reducing blood flow.

Collateral Circulation (Anastomosis):

• Connections between branches of coronary arteries provide backup blood supply.
• Typical near the apex of the heart, but limited elsewhere.
• Function:
  • Develop in response to partial occlusion (atherosclerosis).
  • Cells release cytokines signaling neighboring arteries to grow collateral vessels, maintaining tissue viability.
  • Collateral circulation is a natural protective mechanism but may be insufficient if occlusion is extensive.

Impact of Coronary Blockages:

• Right coronary artery blockage:
  • Can impair SA node function (if that artery supplies it).
  • Can affect the AV node, disrupting conduction and causing ECG changes.
  • May result in arrhythmias or conduction disturbances.
• Left coronary artery blockage:
  • Endangers the left ventricle—the main pump for systemic circulation.
  • Damage here can cause left-sided heart failure, reducing cardiac output.
  • Organ hypoperfusion leads to organ failure if persistent.

Note:

Damage to these arteries can be either:

• sudden (acute) giving rise to an infarction (obstruction of blood supply causing death of tissue) or
• gradual (chronic ischemia), depending on the extent and progression of blockages.

Summary:

The heart’s own blood supply from the coronary arteries is vital for its function. Blockages can impair conduction (via the SA or AV nodes) or reduce pumping ability. Collateral circulation offers some protection but is limited. The location and severity of arterial obstruction determine whether a patient experiences arrhythmias, ischemia, or heart failure.