Retrograde coronary venous contrast echocardiography: assessment of shunting and delineation of regional myocardium in the normal and ischemic canine heart

Coronary venous injections of sonicated Renografin-76 were performed in seven closed chest dogs during two-dimensional echocardiography to study the ability of this new technique to opacify regional myocardium before and after occlusion of the left anterior descending coronary artery. The balloon of a 4F double lumen catheter was inflated in the great cardiac vein for each contrast injection to prevent backflow through the coronary sinus into the right atrium. Retrograde injections before coronary artery occlusion generally resulted in patchy myocardial contrast uptake. Injections after coronary occlusion always resulted in confluent and transmural myocardial opacification which occupied 42.8 +/- 8.6% (range 26 to 54) (mean +/- standard deviation) of the myocardial circumference. Retrograde opacification always extended into adjacent myocardium beyond the ischemic zone, which was assessed in echocardiograms with antegrade contrast injections into the left main coronary artery and which measured 30 +/- 6.3% of the ventricular circumference. Shunting from the coronary venous system to cardiac chambers was evaluated in a parasternal four chamber view and was graded on a scale of 0 to 4+. Contrast appearance was equally intense in the right atrium and right ventricle (3.5 +/- 0.6+, range 2+ to 4+), less intense in the left ventricular cavity (1.5 +/- 0.6+, range 1+ to 3+) and absent in the left atrium. Postmortem anatomic validation with retrograde great cardiac vein injections of indocyanine green corroborated and in vivo contrast appearance in chambers. Retrograde coronary venous contrast echocardiography appears capable of providing in vivo information about the extent and location of myocardial zones that can be reached by retrograde infusions of therapeutic agents and about the ability of these agents to reach ischemic myocardium. In addition, this new method allows for in vivo evaluation of shunts between coronary veins and cardiac chambers, which may influence the efficacy of retrograde interventions.