Branch Of Circumflex Artery Research Articles

Functional and antiischaemic effects of the phosphodiesterase inhibitor levosimendan in isolated rabbit hearts.

Several phosphodiesterase inhibitors have been reported to possess antiischaemic properties by improving myocardial oxygen demand/supply balance. Levosimendan is a new phosphodiesterase inhibitor with calcium-sensitizing properties. We investigated the functional and antiischaemic properties of levosimendan in isolated electrically-driven rabbit hearts (Langendorff, constant perfusion pressure: 70 cm H2O, Tyrode solution, Ca++ 1.8 mmol/l, 37 degrees, 200 beats/min.). Acute regional myocardial ischaemia was induced by ligature of a circumflex artery branch and quantified from epicardial NADH-fluorescence photography. The left ventricular pressure was similarly enhanced by levosimendan 10(-7) M or 5 x 10(-6) M (+15%) (P < 0.05). The global coronary flow was increased more markedly by levosimendan 5 x 10(-6) M (+35-50%) compared to 10(-7) M (+25%) (P < 0.05). The relative coronary flow (= global coronary flow/pressure-rate-product) was significantly enhanced only by levosimendan 5 x 10(-6) M (+20-35%) (P < 0.05), but not by levosimendan 10(-7) M (+10-15%) (P > 0.05). Epicardial NADH-fluorescence area and intensity were significantly diminished by levosimendan (-20%) (P < 0.05), and there was no significant difference between myocardial ischaemia reduction by levosimendan 10(-7) M and 5 x 10(-6) M (P > 0.05). Levosimendan is an inotrope with coronary dilator activity, showing antiischaemic effects in isolated rabbit hearts. These may be caused by (1) phosphodiesterase-inhibition and improvement of myocardial perfusion and/or (2) by oxygen-sparing effects, related to calcium sensitization of myofilaments, particularly at lower concentrations associated with a lower coronary dilator activity.

Intramyocardial Coronary Arteries: Dissection During Coronary Artery Bypass Surgery in 70 Patients

Between October, 1983, and January, 1991, of a total of 395 patients who underwent coronary artery bypass (CAB) surgery, 70 (17.7%) had dissection and vein (65.7%) or internal thoracic artery (ITA; 34.3%) grafting of intramyocardial (IM) coronary arteries for significant proximal coronary artery disease (CAD). The IM left anterior descending (LAD) artery was dissected and grafted in 58.6%, the IM branches of the circumflex artery (CFA) in 31.4%, the IM posterior descending artery (PDA) in 1.4%, and multiple IM arteries in 8.6% of the patients. The LAD artery was usually dissected distally at the site of reemergence, and then, the myocardium was transected cephalad, as were the CFA branches, by cutting the overlying myocardium over them. The intracavitary or subendocardial LAD arteries were dissected, grafted, and elevated to permit closure of the opened left ventricle (LV) beneath. There were no complications related to the dissection of the IM arteries. The IM arteries are usually of a larger diameter and more often free of atherosclerosis. Therefore, they should be dissected and grafted in patients suffering from significant proximal atherosclerotic disease.