Management of type A aortic dissection complicated by coronary ischemia

We read with great interest the article by Doguet et al. concerning the successful use of extracorporeal membrane oxygenation (ECMO) in a patient operated for acute type A aortic dissection (AAAD) and suffering from myocardial ischemia due to the dissection of the right coronary cusp [1].

Myocardial ischemia secondary to AAAD is known to dramatically increase the mortality associated with surgical repair. However, there are two points regarding the surgical management the authors described that we would like to comment upon.

First, the authors noted that they used retrograde cardioplegia as a mean of myocardial protection. One of the main drawbacks of retrograde cardioplegia is precisely the fact that it does not protect correctly the territory of the right coronary artery (RCA) [2], and thus it is advisable to associate it with antegrade cardioplegia to the RCA, either via the right coronary ostium or through a saphenous graft. As the preoperative electrocardiogram showed signs of myocardial ischemia in the RCA territory prior to the operation, our attitude would have been to perform the saphenous graft to the RCA as soon as possible during the cooling phase of cardiopulmonary bypass. This graft would have served as a conduit for reperfusion of blood via a derivation from the arterial line, thus limiting the ischemic insult to the myocardial territory of the RCA, and then, after inducing hypothermic circulatory arrest, protect the heart by combining retrograde and right coronary antegrade cold cardioplegia.

Second, it is usually advisable, once the aortic repair has been performed, to perfuse the aorta for the rewarming period in an antegrade fashion either through the aortic Dacron graft or through the axillary artery in case the latter has been previously chosen as an arterial cannulation site. The goal of this is to avoid continuous retrograde perfusion of a dissected descending aorta. We agree with the authors about the fact that femoral cannulation is easier and faster to perform when the patient is suffering from an unstable hemodynamic condition; however, we think that while on cardiopulmonary bypass, a 2-cm Dacron side-graft to the right axillary artery would have better served as an arterial cannulation site for the ECMO arterial cannula. The wound closed over the Dacron side-graft minimizes the risk of bacterial contamination.

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