Objective: This study was to determine whether simultaneous antegrade-retrograde cardioplegia through a single coronary artery and the coronary sinus provides sufficient and homogeneous perfusion to the heart.
Methods: Simultaneous antegrade-retrograde 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 coronary artery, respectively. The efficacy of simultaneous antegrade-retrograde cardioplegia for myocardial perfusion was assessed by monitoring the distribution of magnetic resonance contrast agent and measuring the effluent from the venting coronary arteries.
Results: Injection of contrast agent into a perfusing artery during simultaneous 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 arteries was lightened with contrast agent given into the coronary sinus during simultaneous antegrade-retrograde cardioplegia. Myocardium in the perfusing artery territory and right ventricular wall remained dark. Moreover, a significant amount of effluent was collected from the venting arteries during simultaneous antegrade-retrograde cardioplegia: 4.7 to 7.8 mL/min from the right coronary artery; 10.5 to 17.7 mL/min from the left anterior descending artery; and 9.7 to 15.2 mL/min from the left circumflex coronary artery.
Conclusions: Simultaneous antegrade-retrograde cardioplegia through a single coronary artery and the coronary sinus provides homogeneous perfusion to the entire heart. During simultaneous antegrade-retrograde cardioplegia, arterial flow supports its own designated myocardium, as well as adjacent myocardium normally served by the venting arteries; the arterial route also supports the right ventricular free wall when the right coronary artery is vented. Venous perfusion of simultaneous antegrade-retrograde cardioplegia mainly supports myocardium in the territories of the venting arteries and does not perfuse the right ventricular free wall. Blood flow delivered to myocardium normally supported by the venting arteries is believed to be sufficient to prevent ischemic injury.