Arterial Coronary Bypass Grafting

Targeting the Interventricular Septum

We read with great interest the article by Gaudino et al. (1) on the choice of conduits in coronary artery surgery. They propose an algorithm for graft selection for the second target vessel considering technical, anatomic, and conduit patency characteristics. They focus on the lateral wall, as the second target vessel, and they consider the radial artery and the right internal thoracic artery as similar alternatives. The inferior wall is considered as the third target and revascularization with a great saphenous vein is advocated, unless distal branches of the right coronary artery are critically stenosed (>90%); in such cases, in situ gastroepiploic or radial artery is preferred.

Based on physiological data, the inferior wall should be regarded as a functionally important myocardial territory because it consists of parts of the right and left ventricles and a significant portion of the interventricular septum (2). The interventricular septum plays a key role in the functioning of both ventricles through ventricular interdependence. Moreover, inferior infarcts are associated with a high rate of complications and a dismal prognosis as compared with lateral infarcts. Thus, we raise the concept that the dominant posterior descending artery, which supplies the inferior wall, should be equally considered as the second target vessel and receive an arterial graft. By implementing this strategy, the anterior and posterior aspects of the septum are revascularized with the best conduits in terms of long-term patency, namely the left internal thoracic artery and the right internal thoracic artery, respectively. Grafting the posterior descending artery overcomes concerns regarding reduced patency of arterial grafts to a dominant right coronary artery (3), which is attributed mainly to competitive flow and to progression of disease to the crux. Furthermore, this pattern has been associated with excellent long-term patency rates in large series and is advocated in terms of a potential prognostic benefit (3,4).

In principle, the quest for an optimal surgical revascularization strategy should not focus exclusively on the severity of target vessel stenosis, but should also take into account the dominance of coronary circulation.

• American College of Cardiology Foundation