Technique of Retrograde Infusion
In 1956, Lillehei and his colleagues proposed the technique of retrograde infusion of cardioplegic solutions directly into the coronary sinus. Many practitioners have found this method to be as effective as antegrade infusion, though it often results in less perfusion of the right ventricle (especially its midsection) and right atrium. To address this issue, retrograde infusion can be administered through the right atrium and right ventricle instead. Retrograde coronary sinus infusion is particularly beneficial in cases with acute high-grade coronary artery stenoses or obstructions.
Surgeons should plan to deliver cardioplegia either antegrade, retrograde, or both. This involves placing a purse-string suture in the right atrial wall and creating a small incision through which the retrograde infusion catheter is introduced and guided into the coronary sinus. The catheter is then connected to the cardioplegia infusion line and de-aired, with the pressure measurement arm attached to a manometer. It is crucial to ensure that the coronary sinus pressure does not exceed 50 mmHg during infusion.
The decision to use a combined antegrade-retrograde or solely retrograde approach varies among surgeons. No definitive advantage of retrograde over antegrade cardioplegia has been established for elective surgeries. However, retrograde infusion is often preferred for aortic valve replacement, mitral valve operations, and many procedures involving the right atrium for congenital heart disease.
Some institutions have adopted a routine combined approach, using both antegrade and retrograde cardioplegia either sequentially or simultaneously. This method helps achieve rapid electromechanical quiescence, prevents uneven cardioplegic distribution, and maximizes ischemic time while avoiding overdosing. This combined approach has also proven effective in pediatric patients. Thus, retrograde cardioplegia should be seen as a complementary method to antegrade cardioplegia rather than a standalone solution.
Retrograde cardioplegia is particularly advantageous in cases of severe obstructive coronary artery disease, such as left main lesions and acute coronary syndromes. It is also effective in procedures on the aortic valve and ascending aorta that require extended clamp times, such as acute aortic dissections and the Ross procedure.
However, retrograde cardioplegia does have some drawbacks. It can lead to uneven distribution to the right ventricle and occasionally encounter complications such as a left superior vena cava that goes unnoticed. There may be difficulties in placing or maintaining the retrograde cannula, and it may provide less protection in hearts with severe left ventricular hypertrophy. Application in children and neonates can be challenging or sometimes impossible. Additionally, coronary sinus rupture is a known complication, though it can be managed with fine suturing or oversewing. Lastly, retrograde cardioplegia often requires additional cannulae, which can clutter the surgical field and may not always justify its benefits.
