The operation to repair ALCAPA by coronary reimplantation to the ascending aorta is commenced through a median sternotomy. Cardiopulmonary bypass (CPB) techniques and aortic cross-clamping require important considerations to avoid unsuspected myocardial ischemia. Before CPB is performed, the right and left main pulmonary arteries are controlled with snuggers in anticipation of engagement shortly after the initiation of CPB. The cardioplegic catheter is placed in the ascending aorta, also before the commencement of CPB. The cardioplegia administration must be coordinated with the perfusion team, as blood cardioplegia is prepared shortly after the commencement ofCPB. The intent in ALCAPA repair is to commence antegrade cardioplegia immediately after the start of CPB, to prevent coronary runoff and ischemia. The surgeon may elect to use crystalline cardioplegia or to employ other special measures to establish blood cardioplegia. We use the following stages in short order to administer antegrade cardioplegia before any period of ischemia can occur:
Cardiopulmonary bypass is initiated with cooling to 32°Celsius and proper venous drainage.
The aorta is immediately cross-clamped and antegrade cardioplegia is started.
The right and left pulmonary arteries are completely snugged, thereby preventing cardioplegia runoff through the intercoronary collaterals from the right coronary artery.
A vent is then placed in the right superior pulmonary vein into the left ventricle.
The administration of cardioplegia is completed with epicardial iced saline.
If there are any problems with cardiac arrest, the team can infuse retrograde cardioplegia, which should be available.
The pulmonary artery is then transected (Fig. 20.2), and the ALCAPA is noted. Careful excision of the coronary artery button is then performed, making sure to avoid any injury to the pulmonary valve leaflets, as noted in Fig. 20.3. The dotted line in the ascending aorta identifies the location of the aortotomy for the eventual reimplantation. Figure 20.4 shows the performance of the anastomosis from the coronary artery to the ascending aorta. Also noted is the pericardial patch in the pulmonary artery moiety, the result of the coronary artery mobilization. Once the coronary artery implantation is completed, the air maneuvers can be instituted and followed by cross-clamp removal. The end-to-end pulmonary artery reconstruction is then completed and followed by separation from CPB (Fig. 20.5).
Often, the surgeon finds extensive venous and arterial collateral vessels surrounding the anomalous coronary artery. In addition, mobilization may prove to be too hazardous for safe primary reimplantation. Under these circumstances, careful and individual ligation of the collaterals is required. Coagulating these vessels rarely stops the bleeding. When the distance is too long for primary reimplantation, a PTFE interposition graft is used for a safe and untethered anastomosis. Figure 20.6 shows the PTFE interposition graft being anastomosed to both the coronary artery and the ascending aorta. Sound judgment determines the caliber and length of the graft. (A 4- to 8-mm graft can be used.) Figure 20.7 depicts the completed graft after separation from CPB.
Anomalous right coronary artery arising from the pulmonary artery in the adult is quite rare, but the same principles and techniques apply. In this case, the rich collaterals arise from the left coronary artery and perfuse the right coronary artery distribution. All the same protective techniques of CPB and myocardial preservation should be employed. Figure 20.8 shows aortobicaval CPB, right and left pulmonary artery snuggers, aortic cross-clamping, antegrade cardioplegia, coronary artery button harvesting, and the location (dotted lines) where the right coronary artery button is to be implanted. Figure 20.9 shows the right coronary button being anastomosed to the ascending aorta; the completed pulmonary artery pericardial patch augments the proximal pulmonary artery trunk. Figure 20.10 shows the completed procedure.
More challenging techniques are employed to repair an ALCAPA from the posterior right pulmonary artery. Figure 20.11 shows the simulated retroaortic posterior right pulmonary artery anatomic origin (dashed lines) of the ALCAPA. The techniques governing CPB and cardioplegia administration are identical to those discussed previously. Figure 20.12 shows the inter-relational anatomy after aortic transection, pulmonary artery mobilization, and segmental resection of the right pulmonary artery containing the ALCAPA origin. Figure 20.13 shows the initial steps of the reconstruction, in which the coronary artery is rotated clockwise 90° and sutured to the posterior ascending aorta without tension. This aortic reconstruction facilitates an end-to-end anastomosis with the ascending aorta. First, however, the pulmonary artery is reconstructed to avoid any undue traction on the completed aortic reconstruction. Figure 20.14 shows the right pulmonary artery reconstruction by a combined end-to-end posterior anastomosis using interrupted suture technique, and anterior pericardial augmentation using running suture technique (Fig. 20.15). The repair is completed by aortic reconstruction by end-to-end anastomosis, air maneuvers, cross-clamp removal, rewarming, and separation from CPB. The final reconstruction after decannulation is shown in Fig. 20.16. The dashed lines represent the posterior coronary button anastomosis.
Unlike neonates and infants undergoing this operation, adults with ALCAPA have normal or near-normal ventricular function owing to their rich collaterals. Usually prompt separation from CPB can be anticipated, and only very rare cases require extracorporeal membrane oxygenation.
20.2 Anomalous Aortic Origin of the Coronary Arteries
Anomalous aortic origin of the coronary arteries (AAOCA) represents about one third of all congenital coronary artery malformations. Unlike ALCAPA, AAOCA involves anomalies of aortic origin rather than pulmonary artery origin. The ischemic problems relate to anatomic courses, stenoses, and compression leading to coronary syndromes and sudden death. These malformations are often found in young patients who collapse and die while participating in sports. They are also noted in older patients whose ischemic symptoms have been identified through echocardiographic evaluation. All the coronary arteries can be involved. Indeed, almost every combination has been reported.
In general, most AAOCAs are thought to be nonthreatening. Exception are anomalous origin of the left main coronary artery from the right aortic sinus of Valsalva (left-from-right) and anomalous origin of the right coronary artery from the left aortic sinus of Valsalva (right-from-left); these anomalies are correlated with ischemic symptoms and sudden death. The vexing problem is that the first symptom in some of these cases is sudden death, so some authors advocate for prophylactic coronary artery unroofing in all cases of left-from-right and in select cases of right-from-left AAOCA.
Diagnosis of AAOCA has improved because of heightened awareness and diagnostic imaging studies that have resulted in more patients coming to the attention of clinicians. Though recent retrospective studies have documented the danger of observing these patients, no consistent consensus has emerged, except perhaps for uniform acceptance of surgery for left-from-right AAOCA. An ongoing multi-institutional study has been organized to document the medical and surgical long-term outcomes of these patients.
20.2.1 Right Coronary Artery from Left Aortic Sinus of Valsalva
Anomalous right coronary artery arising from the left aortic sinus of Valsalva (right-from-left AAOCA) can be found in about 6–27% of all coronary congenital anomalies. Ischemic symptoms, myocardial infarction, syncope, and atrioventricular block are related to the abnormal anatomy, which is characterized by a slit-like and stenotic orifice within the left coronary sinus as well as an associated intramural course within the wall of the aorta of varying distances en route to the right coronary sinus, where it exits to the epicardial surface. Ischemic symptoms or sudden death owing to intermittent closure or stenosis of the anomalous ostium within the aortic wall occurs during exercise or hypertensive crises. Pulmonary stenosis with post-stenotic dilatation can also cause this pressure on the coronary artery course. These pathoanatomic conditions cause left ventricular dysfunction during exertion as enlargement of the aortic root and pulmonary artery contribute to coronarycompression.
The pathway of the anomalous right coronary artery generally traverses above or downstream of the commissure between the left and right coronary sinuses. In most cases, the intramural coronary pathway is 1–2 mm upstream of the commissure and therefore represents no threat to aortic leaflet function during the unroofing operation. Rarely, the intramural course passes from one sinus of Valsalva to the other below the commissure or upstream from it. Surgical management of this anatomic arrangement requires more challenging techniques to spare the aortic valve leaflets.
The operative techniques for repair of AAOCA are straightforward and involve aortobicaval CPB, left ventricular venting, antegrade/retrograde cardioplegia, and aortic transection or near transection (Fig. 20.17). In the case of aortic transection, corresponding marking sutures (not shown in the drawing) are placed at the respective ascending and proximal aorta sites to facilitate accurate reanastomosis. The anomalous right coronary orifice and the left coronary orifice are measured by graduated dilators and recorded. A dilator is then advanced into the tunnel to confirm the intramural course to the right coronary cusp. The length of the intramural tunnel is also measured by a ruler. The dashed lines in Fig. 20.17 depict the intramural course of the anomalous right coronary artery. The unroofing procedure is shown in Fig. 20.18 and demonstrates the unroofed segment as it courses from the left coronary cusp to the right coronary cusp, whereupon it exits onto the epicardial surface. The incision into the slit-like orifice commences with a scalpel or scissors (as in the drawing) and progresses upstream to the aortic commissure and subsequently to thecoronary artery exit site.
A carpenter would exclaim, “Measure ten times; cut once.” This is sound advice. The unroofing maneuver as it extends into the exiting portion of the anomalous artery requires careful attention to opening the orifice adequately for a nonobstructive neo-orifice, while not extending the incision too much so that it passes through the aorta/coronary junction to the epicardial surface the heart. Extending the incision to form the neo-ostium should be performed gradually and stopped when the orifice is identified, to allow inspection and advancement of an appropriately sized dilator without difficulty. If an unintended and unwanted incision outside of the heart is made, the intimal surfaces must be reattached using interrupted monofilament sutures before the operation continues. Failure to perform this reparative part of the procedure effectively will result in dissection, bleeding, and coronary occlusion during attempts to separate from CPB. Prompt resumption of CPB, aortic cross-clamping, and effective repair of the coronary/aortic tear with a biological patch will be necessary, as reviewed later in this chapter (Figs. 20.35, 20.36, 20.37, 20.38, 20.39, 20.40, 20.41, and 20.42).
Once the intramural segment is safely and effectively unroofed, the distance is measured and recorded. Occasionally, the common wall (tunica media) is very thick, and leaving it simply unroofed could threaten the neo-orifice by obstruction, as the sides of the tunica media could just flap back and recreate the original stenosis. It is therefore wise and prudent to consider resection of a large portion of the common wall using endarterectomy techniques. The unroofed segment may result in an intimal gap between the coronary artery wall and the aortic wall. This gap requires tacking sutures, which are placed to reapproximate the intimal edges to avoid dissection and bleeding after separation from CPB. Figure 20.19 shows the interrupted tacking sutures placed at the neo-orifice of the right coronary artery in the right coronary cusp. The rest of the unroofed segment also requires tacking sutures to complete this part of the operation. Some surgeons prefer a running suture technique for this part of the operation, but we prefer fine monofilament interrupted sutures.
In very rare circumstances, the right-from-left AAOCA courses from the left coronary cusp to the right coronary cusp upstream from or below the commissure. Repair of this configuration is more challenging because the aortic commissure and associated leaflets are subject to injury during the unroofing procedure. More thoughtful reparative techniques are required. Figure 20.20 demonstrates the aortic root exposure after all of the preparatory maneuvers (CPB, cardioplegia, etc.) have been employed.
A calipered probe measures the orifice diameter, and when advanced past the commissure, an incision can be made in the tunica media (the shared wall between the coronary artery and the aorta), which can expose the course of the intramural coronary artery. Figure 20.21 demonstrates incision and unroofing of the proximal tunnel within the left coronary sinus and complete unroofing within the right coronary sinus. A probe is placed into the unroofed coronary artery to demonstrate the arterial course. Following the same recommendations as noted previously, careful incisions are important during the procedure to avoid injury to the aortic valve leaflets and prevent any transmural incisions to the epicardial surface of the heart. Figure 20.22 shows the completed unroofing procedure and features tacking sutures to approximate the intimal flaps of the coronary artery and the aorta. As previously noted, these interrupted sutures along the entire length of theunroofing prevent dissection, hemorrhage, and coronary artery occlusion.