<prompt> Coronary blood flow to the left ventricle increases during all ExceptEarly systoleMyocardial hypoxiaStimulation of sympathetic nerves of the heaAerial hypeension  <response>: During early systole, coronary blood flow falls as coronary vessels are compressed by the contracting myocardium.A fall in PO2 has a potent vasodilator effect on coronary vessels. Adenosine released from hypoxic myocardium is also a potent vasodilator.Sympathetic stimulation increases the rate and force of contraction; the resulting increase in the rate of production of vasodilator metabolites dilates coronary vessels.Myocardial work and metabolism are increased in hypeension.Ref: Guyton; 13th edition 