Cardioplegia Solution

• arrest of the heart during cardiac surgery

• provides a bloodless field

• protects the myocardium from cell death

• given after cardiopulmonary bypass has been instituted and aortic cross clamp applied 

• when solution is introduced into the aortic root (with an aortic cross-clamp on the distal aorta to limit systemic circulation), this is called antegrade cardioplegia. When the solution is introduced into the coronary sinus it is called retrograde cardioplegia

  • chemically (high potassium solution)

  • hypothermia (usually at 4 °C)

    • oxygen consumption will drop by 50% for every 10 °C reduction in temperature

 

Antegrade

• catheter placed into aortic root (at the site of a planned proximal coronary anastomosis)

• its administration depends on a competent aortic valve and hence it should not be used in patients with aortic regurgitation

• if aortic regurgitation present, antegrade cardioplegia can be administered directly into the coronary ostia (direct administration of cardioplegia carries the potential danger of coronary artery dissection, selective introduction and perfusion only into the LAD or circumflex artery in patients with a short left main coronary artery, and also carries the possiblity of late ostial coronary artery stenosis

• leads to better cooling of the right ventricle compared to retrograde cardioplegia administration alone

 

Retrograde

• catheter is placed into the coronary sinus

 

Coronary Artery Disease

• patients with coronary artery disease, cardioplegia maldistribution can occur with the use of antegrade cardioplegia alone, which is avoided when combined with retrograde cardioplegia administration

• in the absence of coronary artery disease, antegrade cardioplegia leads to an even distribution of cardioplegia

• even though there is no evidence of an additional benefit of retrograde cardioplegia in the absence of coronary stenosis, we find a combination with retrograde cardioplegia administration useful for complex procedures requiring a prolonged clamp time, as intermittent retrograde cardioplegia can be administered without interruption of the surgical procedure

 

Venting the aortic root after the administration of cardioplegia

 

Controversies

• it is controversial if antegrade cardioplegia protects the right ventricle better than retrograde cardioplegia

  • In a dog model with temporary ligation of the left anterior descending coronary artery, antegrade cardioplegia administration led to a better cooling and preservation of right ventricular function than retrograde cardioplegia [4].

  • In clinical studies, a better protection of the right ventricle with antegrade cardioplegia is more difficult to demonstrate.

  • One randomized study demonstrated a preserved postoperative right ventricular function with antegrade cardioplegia in coronary artery bypass patients without right coronary artery (RCA) stenosis as opposed to a decreased right ventricular function in the early postoperative phase with the use of retrograde cardioplegia alone [5]. In the same study, inadequate protection of the right ventricle was found in all patients with RCA stenosis, irregardless if only antegrade or retrograde cardioplegia was administered.

  • Therefore, it appears advisable to use antegrade as well as retrograde cardioplegia to protect the right ventricle in the presence of RCA stenosis

  • another study demonstrated that right ventricular cooling appears to be more effective if both antegrade and retrograde cardioplegia are employed compared to antegrade cardioplegia administration alone

• The problem of maldistribution of the cardioplegia solution in patients with coronary artery disease with antegrade cardioplegia alone has been well documented, as antegrade cardioplegia administration appears to provide inferior cooling distal to severe coronary stenosis than retrograde administration

• In high-risk coronary patients, outcomes with antegrade cardioplegia alone appear to be inferior than a combination of ante- and retrograde cardioplegia administration. However, in patients with preserved LV function, cardioplegia maldistribution appears to have less of a negative clinical impact, and some studies show little to no advantage of combining ante- and retrograde cardioplegia

• Even if in certain patient populations no difference in major clinical events result from the use of antegrade cardioplegia alone, the analysis of more subtle markers of myocardial damage, such as troponin I, demonstrates a better myocardial protection with the combination of antegrade and retrograde cardioplegia than with antegrade cardioplegia alone