The coronary arteries originate off of the ascending aorta and continue onto the surface of the heart (the epicardium). When the heart contracts during systole, the contraction compresses the coronary arteries which prevents<unk> . Therefore, it is only when the heart relaxes, during diastole, that the coronary vessels open up and allow for<unk> ; thus<unk>  is highest during diastole, unlike most other arteries which experience higher<unk><unk> s under systole.<unk>  can be measured by calculating the difference between the aortic<unk>  and the left ventricular end diastolic<unk> :<unk>  <unk>  = Aortic Diastolic<unk>  – Left Ventricular end-diastolic<unk>  (LVEDP) In the research setting, the absolute<unk>  can be measured using coronary and aortic<unk>  transducers, however,<unk>  is not regularly measured in human clinical practice. During cardiac surgery, when a patient is placed on cardiopulmonary bypass, and blood is passed through the coronary vessels in a retrograde direction,<unk>  can be approximated by using the measured right atrial<unk>  in place of LVEDP because the coronary sinus drains into the right atrium.<unk>  is not the sole determinant of Coronary Blood Flow (CBF). CBF is also determined mainly by metabolic autoregulation; sympathetic regulation plays some role in coronary dilation/constriction but less so than in other vascular systems. That is, when the ventricular myocardium is working, it extracts oxygen from the coronary blood and produces adenosine as a by product of ATP use. Hypoxia and adenosine both contribute to coronary vasodilation, which increase CBF. Both higher<unk>  and greater vasodilation will result in higher CBF.
Coronary perfusion pressure
Mean systemic pressure
Cardiac output
Mean arterial pressure
Coronary flow reserve
Vagal tone
Cerebral perfusion pressure
Central venous pressure