CARDIOVASCULAR ENGINEERING Journal for Extracorporeal Circulation, Assist Devices,Transplantation and Artificial Organs
	Volume 8, 2003, No 1-2

Myocardial Perfusion during Simultaneous Antegrade/Retrograde Cardioplegia
G. Tian, B. Xiang, G. Dai, J. Sun, J. Docherty, R. Mangat, T. A. Salerno, R. Deslauriers

Background: This study was to assess the effects of simultaneous antegrade/retrograde cardioplegia (SARC) on myocardial perfusion and energy metabolism in regions distal to a coronary occlusion.
Methods: Isolated pig hearts with an occluded left anterior descending artery (LAD) were used as an experimental model. Magnetic resonance (MR) imaging in conjunction with contrast agent was used to determine whether SARC delivers blood cardioplegia to the myocardium supported by an occluded LAD. Fluorescence imaging was used to determine how blood cardioplegia delivered through the arterial route of SARC flows to the jeopardized myocardium. Localized ³¹P MR spectroscopy was used to determine whether SARC was able to sustain normal energy metabolism in the occluded region of the myocardium.
Results: MR images showed that myocardium in the LAD region brightened during SARC with contrast agent given into either the aorta or coronary sinus. Fluorescence images showed illumination of the anterior ascending cardiac vein and its draining vessels in the LAD region during SARC when a fluorescent dye was given into the left circumflex coronary artery (LCX). ³¹P spectra showed that occlusion of the LAD during antegrade perfusion resulted in a significant decrease in phosphocreatine and an increase of inorganic phosphate. Use of SARC totally abolished the ischemic changes.
Conclusion: Our results suggest that SARC delivers blood cardioplegia through both arterial and venous perfusion routes. It is through veno-venous anastomoses that antegradely delivered blood cardioplegia flows into the occluded region of myocardium. Finally, SARC is able to sustain normal myocardial energy metabolism in arrested heart.

Key words: simultaneous cardioplegia, myocardial protection, myocardial perfusion, myocardial energy metabolism, magnetic resonance spectroscopy and imaging, fluorescence imaging

Ganghong Tian, MD., Ph.D.
Institute for Biodiagnostics
National Research Council of Canada
435 Ellice Ave, Winnipeg
Manitoba, R3B1Y6
Canada
E-mail: Hong.Tian@nrc.ca

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