Hypertriglyceridemia Deteriorates Coronary Flow Reserve Even if There is no Coronary Stenosis: Real-Time Myocardial Contrast Echocardiographic Study

Background. It is reported that hyperlipidemia may deteriorate the coronary circulation by itself. The aim is to examine the effect of acute hypertriglyceridemia on myocardial perfusion using real-time myocardial contrast echocardiography (MCE).Methods. Hypertriglyceridemia was induced by infusion of fat emulsion (Intralipos) in 7 open-chest dogs. The coronary flow was measured by a flow meter, and its reserve (CFR) was determined by adenosine triphosphate (ATP) injection. MCE was examined using SIEMENS Sequoia-512 during infusion of Definity®. The replenishment curve was obtained to measure the A and β value in the equation of y=A(1-e-βt).Results. The β value did not change by hyperlipidemia, however, its increment by ATP decreased significantly at hyperlipidemia. The β value after ATP decreased concomitantly with the increase of both serum triglyceride level and blood viscosity. However, the A value was not affected by either serum triglyceride or viscosity.Conclusions. Hypertriglyceridemia makes blood viscous followed by high shear stress in the resistant vessels. Although myocardial resistant vessels are dilated for its compensatory response, exaggeration of blood flow speed in the capillaries after ATP is impaired due to high viscosity of hyperlipidemia.