What is retrograde cardioplegia, and when is it used?

• A. Delivery of cardioplegic solution via the coronary sinus to perfuse the myocardium from the venous system; used when antegrade delivery is limited or in multivessel disease to protect posterior walls.
• B. Delivery via the aorta to the coronary arteries.
• C. Infusing cardioplegia into the left atrial appendage.
• D. Injecting through the pulmonary artery.

Answer: (A)

Retrograde cardioplegia delivers the protective solution through the coronary venous system, typically by cannulating the coronary sinus so the cardioplegia flows backward through the veins to reach the myocardium. This route is especially useful when forward, arterial delivery from the aorta cannot reliably perfuse all areas—such as in multivessel disease with proximal occlusions or when protecting regions like the posterior walls that may not get adequate arterial distribution. In practice, it provides supplemental myocardial protection and is often used in combination with antegrade cardioplegia to ensure more uniform cooling and arrest, delivered at a controlled venous pressure to avoid venous hypertension. The other routes described do not achieve retrograde delivery through the venous system and are not used for this purpose.