Coronary Artery Blood Flow

• • Coronary artery blood does not flow constantly
  • blood flow is intermittent, which means that the myocardium is perfused intermittently
  • The myocardium is perfused during diastole when the heart muscle is relaxed
  • during systole (contractile phase of the cardiac cycle) blood flow is interrupted
  • This is because as the ventricles contract intra-muscular pressure rises and compresses the coronary arteries halting blood flow
• • although coronary arteries lie on the external surface (epicardium) of the heart, the branches of the arteries penetrate and pass through the bulk of the ventricular muscle mass