Blood acceleration is the principal factor in coronary flow increase during exercise test

Continuous wave Doppler evaluation of the blood flow velocity in the internal mammary artery anastomosed to the left anterior descending coronary artery is a technique for assessing human coronary flow that shows a good reproducibility and lower change in Doppler angle between resting and supine exercise conditions. In this study the reciprocal changes which occur in coronary blood flow, coronary stroke volume, coronary resistance and blood pressure have been studied. During supine exercise coronary stroke volume remains constant and the increase of blood cells acceleration is necessary to have the shortening of cardiac cycle. This parameter is inversely dependent on the coronary resistances and directly dependent on blood pressure. As a consequence it plays the main role in increasing coronary blood flow during exercise.