Effect on myocardial perfusion of simultaneous delivery of cardioplegic solution through a single coronary artery and the coronary sinus

Objective: This study was to determine whether simultaneous antegrade-retro grade cardioplegia through a single coronary artery and the coronary sinus provides sufficient and homogeneous perfusion to the heart. Methods: Simultaneous antegrade-regrograde cardioplegia was conducted in 7 isolated pig hearts through the coronary sinus in conjunction with the left anterior descending artery, the left circumflex artery, and the right coro nary artery, respectively. The efficacy of simultaneous antegrade-retrograd e cardioplegia for myocardial perfusion was assessed by monitoring the dist ribution of magnetic resonance contrast agent and measuring the effluent fr om the venting coronary arteries. Results: Injection of contrast agent into a perfusing artery during simulta neous antegrade-retrograde cardioplegia resulted in increased image signal intensity not only in the territory of the perfusing artery but also in the areas normally served by the other 2 venting arteries (including the right ventricular wall). The myocardium in the territories of the 2 venting arte ries was lightened with contrast agent given into the Coronary sinus during simultaneous antegrade-retrograde cardioplegia. Myocardium. in the perfusi ng artery territory and right ventricular wall remained dark. Moreover, a s ignificant amount of effluent was collected from the venting arteries durin g simultaneous antegrade-retrograde cardioplegia: 4.7 to 7.8 mL/min from th e right coronary artery; 10.5 to 17.7 mL/min from the left anterior descend ing artery; and 9.7 to 15.2 mL/min from the left circumflex coronary artery . Conclusions: Simultaneous antegrade-retrograde cardioplegia through a singl e coronary artery and the coronary sinus provides homogeneous perfusion to the entire heart. During simultaneous antegrade-retro grade cardioplegia, a rterial flow supports its own designated myocardium, as well as adjacent my ocardium normally served by the venting arteries; the arterial route also s upports the right ventricular free wall when the right coronary artery is v ented. Venous perfusion of simultaneous antegrade-retrograde cardioplegia m ainly supports myocardium in the territories of the venting arteries and do es not perfuse the right ventricular free wall. Blood flow delivered to myo cardium normally supported by the venting arteries is believed to be suffic ient to prevent ischemic injury.