Causes of Intermittent Blood Flow

• Coronary artery blood flow is intermittent or pulsatile as a direct consequence of 2 occurrences:

  • the intermittent contraction of the heart
  • when the aortic valve is opened (as on ejection – the culmination of systole)
• Coronary artery blood flow is intermittent or pulsatile as a direct consequence of 2 occurrences - the intermittent contraction of the heart:

  • The contractile phase of the cardiac cycle (systole) produces a rise in myocardial intra-muscular pressure, which compresses the coronary vessels temporarily stopping blood flow
  • The majority of coronary artery blood flow (80%) and therefore myocardial perfusion occurs during diastole when the myocytes are relaxed and the arteries are no longer compressed
• Coronary artery blood flow is intermittent or pulsatile as a direct consequence of 2 occurrences - when the aortic valve is opened:

  • when the aortic valve is opened (as on ejection – the culmination of systole), its flaps partially obstruct the entrance to the coronary arteries further impeding blood flow into the coronary arteries