The findings of this multicenter study of 178 patients showed that Enclose II is a safe and useful assist device for hand-sewn proximal anastomoses during OPCAB. Neither aortic dissection nor new cerebral infarction was associated with this device in any of the patients. Enclose II enables proximal anastomosis without aortic partial clamping. Thus, the Enclose II–related procedure is characterized as gentle enough to prevent the detachment of atherosclerotic plaque or damage to the aorta. The early graft patency rates were similar to those of recent reports using partial aortic side-biting clamps.4,17
This study demonstrated that Enclose II was safe and useful for proximal anastomosis during OPCAB in 178 patients at six centers. More patients underwent OPCAB in the present study than in previous reports. The fact that this series proceeded at six centers is significant because several operators participated under different surgical policies.
The incidence of a loose fit for the ascending aorta in our experience is 1.6%. The reason for this remains obscure, but we speculate that some devices did not follow the curve of the vessel, especially when they were repositioned and pivoted for the second proximal anastomosis. We surmounted this problem using the partial clamp alternative to Enclose II during anastomosis.
Saphenous vein grafts were selected as conduits for relatively younger patients (Table 2). Our series included 61 patients who were older than 75 years and 41 critical or emergency patients for whom a saphenous vein would be preferable as a conduit because it is easier to harvest and 29 patients with more than three coronary branches that were each targeted for revascularization. Saphenous veins have a greater diameter than radial arteries and thus were a better match to form sequential bypasses for this group.
Enclose II has several advantages. Venous and arterial grafts can be used, and various anastomotic shapes can be easily designed, which cannot be achieved using an automated system for proximal anastomosis such as the St. Jude Symmetry device and Cardiac Passport device. Fit with the aorta can be easily assessed by monitoring blood leakage from the drainage tube. Repositioning Enclose II is easy, and it provides a clear bloodless area. Even if a bloodless area cannot be arranged despite correct use of Enclose II, it can be created by suctioning blood from the attached drainage tube. Enclose II offers a clearer bloodless view than the Heartstring system.
One disadvantage of Enclose II is the requirement for two nonatherosclerotic areas on the aorta. One is needed to insert the lower jaw of Enclose II, and the other is needed to create a hole for the anastomosis. On the other hand, Enclose II can be applied when two narrow points are free of atherosclerosis, even if the rest of the aorta is sclerotic. We performed proximal anastomoses using several techniques during OPCAB.
We intraoperatively applied epiaortic ultrasonography to investigate atherosclerotic diseases at the ascending aorta and prevent Enclose II from causing cerebral embolisms. Patients with IMTs of more than 4 mm at the ascending aorta were excluded from application of Enclose II in our series, which is supported by previous reports.19 Wareing and colleagues19 classified patients based on the presence of mild, moderate, or severe atherosclerotic diseases. Our patients with IMTs of 3 mm or less were equivalent to their mild group, which was considered appropriate to undergo standard cardiac surgical procedures to prevent cerebral embolisms. Classically, Mills and Everson1 classified ascending aortic atherosclerosis into three types. We excluded patients with ascending aortic atherosclerosis equivalent to their types I and II if preoperatively determined by CT. Patients with type III atherosclerotic aortae were also excluded based on the findings of intraoperative epiaortic ultrasonography. These protocols did not clinically detect any cerebral infarction caused by Enclose II. Of course, microembolisms might have occurred that were imperceptible on CT images but detectable by magnetic resonance imaging. However, magnetic resonance imaging is usually applied in our hospital only when clinical neurological impairment arises. As a result, the stroke rate in our series was 1.1%, which was equivalent to the 1.2% in the 2012 STS database.
To reduce movement of the ascending aorta, we usually cushion the side of it with layers of folded gauze and attach an Octopus to the basal side. Introducing these two strategies might reduce the rate of membrane rupture caused by sutures and blades. The incidence of membrane damage in the present study was 1.6% compared with reports of 2.5% to 3.0%.14–16 We recommend these simple techniques for all coronary surgeons. The simple attachment and bloodless view of anastomosis sites not only help less experienced surgeons to easily complete the technique but also might prevent cerebral infarctions.
A key limitation of this study is that it was not a randomized controlled trial. Basically, we intend to use Enclose II for all patients who undergo OPCAB and require proximal anastomosis. Therefore, a randomized controlled trial regarding Enclose II is impossible in our hospitals.
We are also unable to describe the sensitivity of the anastomotic stenoses because CT scanning and reconstruction protocols differed among institutions.
The overall safety and value of Enclose II could not be precisely determined in only 178 patients. A study of a larger patient cohort is required to produce concrete conclusions.
Enclose II was safe and useful for proximal anastomosis during OPCAB in 178 patients. However, long-term graft patency remains unknown, and further follow-up is required.
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This is an interesting report on 178 patients in which the Enclose II proximal coronary artery bypass anastomotic device was used for isolated off-pump coronary artery bypass grafting. A total of 222 proximal anastomoses were performed in these patients. Graft patency was evaluated by 64-multislice computed tomography (n = 151) or angiography (n = 23) in all patients who survived surgery between 30 and 1584 days after the procedure. The graft patency was 96.4% after 1 year.
Because this is a relatively small cohort of patients, the safety and efficacy of this device could not be precisely determined; however, the results are encouraging. A major weakness of this analysis was the small number of patients who underwent angiography. The use of computed tomographic scanning does not allow for a detailed look at the quality of the proximal anastomosis. Moreover, there were two neurological events in this series, and it is impossible to completely exclude the contribution of the Enclose II device to these complications. Long-term patency, safety, and efficacy will require a larger experience with a longer follow-up.
The authors are to be congratulated for the careful follow-up and evaluation of their results with the Enclose II proximal anastomotic device.