2007 Volume 5 Issue 3 Pages 72-78
Background. A number of cardiovascular diseases show diurnal variation. However, it is unknown whether coronary circulation exhibits diurnal variation.
Methods. The flow velocities in the left anterior descending coronary artery of 15 healthy men were measured by transthoracic Doppler echocardiography both at rest and during intravenous infusion of adenosine triphosphate at 7 AM, noon, 5 PM and 9 PM. Coronary flow velocity reserve (CFVR) was calculated as the ratio of hyperemic to basal mean diastolic flow velocity. CFVR at 7 AM was significantly smaller than that at 9 PM (p=0.001; 7 AM, 3.23 ± 0.66; noon, 3.89 ± 0.86; 5 AM, 3.46 ± 0.65; 9 PM, 4.41 ± 1.11, respectively). CFVR at 5 PM was also significantly smaller than that at 9 PM (p=0.008).
Conclusions. Diurnal variation in CFVR exists in healthy men. This finding may be related to the diurnal variation in cardiovascular events.