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Eur J Cardiothorac Surg 2005;27:1070-1073
© 2005 Elsevier Science NL

Clinical experience with the Novare Enclose II manual proximal anastomotic device during off-pump coronary artery surgery

Belhhan Akpinar*, Mustafa Guden, Ertan Sagbas, Ilhan Sanisoglu, Mehmet U. Ergenoglu, Cavlan Turkoglu

Departments of Cardiac Surgery and Cardiology, Florence Nightingale Hospital, Abide'i Hürriyet Cad No. 290, 80220 Sisli-Istanbul, Turkey

Received 27 November 2004; received in revised form 14 February 2005; accepted 15 February 2005.

* Corresponding author. Fax: +90 212 239 8791. (E-mail: belh{at}tnn.net).


   Abstract
Top
 Abstract
1. Introduction
 2. Material and methods
 3. Results
 4. Discussion
 References
 
Objective: The aim of this study was to assess the feasibility and safety of a new proximal anastomotic device during off-pump coronary surgery. Methods: The Novare Enclose II is a manual proximal anastomotic device that enables the surgeon to perform proximal anastomoses without side-biting clamps in a fully pressurized aorta. The device was used in 30 off-pump coronary artery bypass graft (CABG) patients (Group A) for performing 25 vein, 10 free right internal thoracic artery and 14 radial artery anastomoses to the aorta.The number of proximal anastomoses varied between 1 and 3 per patient. Intraoperative transcranial Doppler measurements were performed to detect cerebral microemboli during the use of the device and were compared with transcranial Doppler measurements of 30 off-pump patients where a partial side clamp was used for proximal anastomoses (Group B).The aorta was evaluated using transesophageal echocardiography (TEE) and epiaortic echocardiography (EAE) in both groups before the procedure and patients with a calcified aorta were excluded. Results: In Group A, 49 proximal anostomoses were performed as planned with the device using conventional hand-sewn methods. Twenty-four of these were arterial conduits. In Group B, 32 proximal anastomoses were performed using 25 veins and 7 arterial grafts. There were no procedure related to adverse events or complications in both groups. The median number of microemboli was 15 (range 5–48) in Group A and 68 (range 35–290) in Group B (P<0.05). Conclusion: The Enclose II device can be a valuable tool to perform venous or arterial proximal anastomoses during off-pump CABG. Transcranial Doppler results suggest that the device seems to be less traumatizing than side clamping and may reduce clamp-associated complications during off-pump coronary artery surgery.

Key Words: Anastomosis • Device • Off-pump • Surgery


   1. Introduction
Top
 Abstract
 1. Introduction
2. Material and methods
 3. Results
 4. Discussion
 References
 
Manipulation of a diseased ascending aorta can cause a variety of serious complications. Cross-clamping or side-biting partial occlusion clamping of the aorta can lead to local particulate embolization which can result in neurological injury or other serious complications such as aortic wall trauma and even dissection [1–3].

The surgical treatment of coronary artery disease has entered a new era with the development of new techniques and technologies. Proximal anastomotic devices are one of these developments and the primary goal of these devices is to reduce neurological deficits by eliminating the side-biting clamp and to improve the ease of performing a proximal anastomosis [4]. The clinical value of such devices during conventional on-pump coronary artery bypass grafting (CABG) is limited at the moment and will probably remain so in the near future. However, a proximal anastomotic device which can eliminate side clamping in a fully pressurized aorta can be valuable during off-pump CABG. The Novare Enclose II is such a device which allows the surgeon to make an enclosed bloodless field in the fully pressurized aorta without the use of a side-biting clamp and the proximal anastomoses can be performed using conventional methods.

The aim of this paper is to share the clinical experience of the authors with this device during off-pump CABG surgery and discuss certain advantages and pitfalls of the technique.


   2. Material and methods
Top
 Abstract
 1. Introduction
 2. Material and methods
3. Results
 4. Discussion
 References
 
The Ethical Commission of the hospital approved the study protocol. All patients received information about the study and were asked to sign an informed consent. Indications for the use of the device were patients undergoing off-pump CABG who would receive at least one proximal anastomoses. Patients were then randomly assigned either to Group A where the new device would be used or to Group B where proximal anastomoses would be performed using a side-biting clamp. All cases were operated by the same surgeon. Evaluation of the aorta was done by perioperative transesophageal echo (TEE), epiaortic echo (EAE) and surgical palpation. Patients with a calcified aortic wall or with patchy areas of atherosclerosis were excluded.

2.1. EAE
After sternotomy and opening the pericardium, the pericardial sac was filled with warm saline to optimize imaging. EAE was then performed using a 2.5–4mHz probe (Acuson 128 xp/5C Mountain View, CA) covered with a sterile custom made drape.

2.2. Transcranial Doppler (TCD) evaluation
TCD examination of the left and right middle cerebral arteries was performed using a Multi-Drop X4 device (DWL, Sipplingen, Germany) using 2MHz probes which were transtemporally positioned above both zygomatic arch. A special software (TCD-8 for Multi-Drop X4, version 8.00q) allowed to make differential analysis between emboli and artifacts. TCD measurements were performed during the period of performing the proximal anastomoses; that is insertion and removal of the device in Group A and during side clamping and removing the clamp in Group B. In Group B, all proximal anastomoses were performed using single side clamping.

The Novare Enclose II is a manual proximal anastomotic device that has both FDA and CE approval. It consists of a lower jaw with an expandable membrane and an upper jaw with a non-expandable wireform. Both jaws are manipulated by the surgeon through the lower and upper knobs.The vented plug ensures hemostasis during the procedure (Fig. 1).The device comes with a kit which also includes a large bore needle (14g) which serves as an introducer, an actuator tool to manipulate the upper and lower knobs and a 3.5mm aortic punch.



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  		Fig. 1. Figure of Novare Enclose II manual proximal anastomotic device with opened lower jaw.

 
The procedure begins with marking the point of proximal anastomosis on the aorta. The systolic blood pressure was maintained between 80 and 90mmHg during the procedure. Although patients with aortic wall disease were excluded in this study, it is vital to have two points in the aorta which are free of disease, one for the insertion of the expandable lower jaw, second for the site of the anastomosis. After anticoagulation with heparin, the 14g needle was introduced into the aorta through a 4-0 prolene purse string suture. The lower jaw of the device was then inserted through this hole and advanced towards the point of the proximal anastomosis. At this point the upper jaw was lowered until it touches the aortic wall and the membrane of the lower jaw was opened. The upper jaw was further tightened (Fig. 1). The vented plug can be used to remove extra blood remaining in the anastomosis area, but is usually not necessary. The system basically acts as a reversely positioned umbrella in the aorta which creates a 1cm2 bloodless area between the upper and lower jaws of the device. A small longitudinal incision was made in the middle of this 1cm2 area and excess aortic tissue was removed using the 3.5mm aortic punch. Care must be taken not to make a too deep incision and damage the lower membrane. The proximal anastomoses was then performed in the usual fashion, using 6 or 7-0 polypropelene sutures depending on whether a venous or arterial conduit was used (Fig. 2). The edges around the hole give the surgeon enough space to take adequate bites from the aorta, however, as mentioned earlier, these bites should not be too deep to prevent damage to the lower membrane. After the anastomosis was completed, a bulldog clamp was placed on the conduit. First, the lower membrane was closed followed by the lifting of the upper jaw. After the conduit was filled with blood and deairing was completed, the device was repositioned for a second anastomosis. After the proximal anastomoses were completed, the device was removed and the purse suture was tied down. The system allows up to three anastomoses from one insertion site. The sequence of proximal and distal anastomoses was left to the choice of the surgeon.



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  		Fig. 2. Figure of Novare Enclose II device during the anastomosis. (A) Saphenous vein. (B) Hole for the proximal anastomosis.

 
In Group B, the LITA to the LAD anastomosis was performed first in all cases, followed by RITA to the RCA anastomoses in five cases. Then, similar to Group A the systolic aortic pressure was regulated between 80 and 90mmHg and the side clamp was applied. All proximal anastomoses were performed under single side clamping, followed by the distal anastomoses.

2.3. Statistical analysis
The number of microemboli is presented as median. The Mann–Whitney U-test was used to compare the difference in microembolisation between two groups.


   3. Results
Top
 Abstract
 1. Introduction
 2. Material and methods
 3. Results
4. Discussion
 References
 
In Group A, the device was used in 30 off-pump CABG cases to perform 49 proximal anastomoses. There were 25 vein, 10 free Right Internal Thoracic Artery (RITA) and 14 radial artery (RA) connections to the aorta. The number of anastomoses varied between 1 and 3 per patient and all anastomoses could be performed as planned. There were no complications related to the use of the device.

In Group B, 32 proximal anastomoses were performed. These consisted of 25 veins, 5 radial arteries and 2 free RITA grafts. There were no side clamp-related complications.

None of the patients in both groups experienced a major or minor neurological deficit postoperatively.

Transcranial Doppler evaluation during aortic manipulation could be performed in 26 patients in Group A and 23 patients in Group B due to anatomical reasons and difficulties in signal detection.TCD revealed a significantly higher number of microembolic hits in Group B (68) when compared to Group A (15) P<0.05. The number of microembolic signals reached the highest level during removal of the side clamp in Group B while a significant pattern was not observed in Group A.


   4. Discussion
Top
 Abstract
 1. Introduction
 2. Material and methods
 3. Results
 4. Discussion
References
 
Most patients who undergo a coronary revascularisation procedure today are older and have many illnesses that can lead to increased morbidity and mortality [4]. The aim during treating these patients should be reducing surgical trauma without compromising the quality of surgery. In addition to elimination of cardiopulmonary bypass a number of other technologies have been developed to reduce these risks [4,5]. Among many other complications, neurological injury is a major concern after CABG, especially in high-risk patients. Although off-pump CABG has been associated with lower neurological complications, many studies have suggested that aortic manipulation is a major cause for such injury and the combination of off-pump CABG and a ‘no touch technique to the aorta’ is the key to minimizing these complications [5,6]. Besides the release of plaque from the aortic wall, partial occlusion clamps have also been associated with aortic trauma that may lead to aortic dissection [3]. Total arterial revascularization and the use of T and Y grafts have largely reduced the use of side-biting clamps during OPCAB surgery but these techniques may not be feasible for all patients [7,8]. Another issue in high-risk patients undergoing off-pump CABG is the higher rate of incomplete revascularization [4]. In that context, proximal anastomotic devices have been introduced to reduce aortic manipulation and therefore associated complications. Proximal anastomotic devices have been classified as either automatic or manual [9]. The automatic devices allow anastomoses between the conduit and aorta through automated connectors and deployment systems. Automatic anastomotic devices using the connector technology are technically more complex and problems regarding cost and early patency rates have been reported [4,9,10]. Lower patency rates have been attributed to the 90° angulation of the venous graft with the aorta leading to kinking and contact of blood with foreign material [9,10]. Another drawback is that the current devices only allow veins to be used as conduits.

Manual systems create a limited bloodless area in the aorta for proximal anastomoses when cross clamping is deemed hazardous and this enables the surgeon to create a conventional hand-sewn proximal anastomosis [4,9]. The Enclose II is a low profile manual anastomotic device that acts as a reverse umbrella inside an aortotomy. The space between the lower membrane and upper jaw provides adequate space for conventional suturing. With the Enclose II device, the surgeon makes the proximal anastomosis of a vein or arterial graft on the aorta using standard suturing techniques. Unlike the connector technology that eliminates both the side-biting clamp and the traditional anastomosis technique, this device preserves the well-documented high patency rates and hemodynamics of hand sutured proximal anastomosis [9]. Another major advantage is that the system allows arterial conduits to be used for proximal anastomoses.

The major drawback of the Enclose device is that it involves an alternative access site, and some degree of aortic trauma during insertion and manipulation can occur. There must be at least two areas free of disease on the aorta to use the device; one for the introduction of the lower jaw, and the second for the target proximal anastomosis spot. The device cannot be used in a totally calcified aorta. However, in cases with patchy areas of a diseased aorta, epiaortic or transesophageal echocardiography can be used to guide the device during the procedure. Such a study is under way in the author's institution. Another shortcoming is that it is a single use device and this will inevitably increase surgical cost. On the other hand, being able to perform more than one proximal anastomoses through a single insertion point is an advantage over other anastomotic devices. As mentioned earlier, the introduction of the device through the aorta or opening of the membrane can cause trauma but the device exerts substantially less pressure on the aortic wall and potentially decreases vessel trauma that may lead to intimal damage and embolization.Transcranial Doppler (TCD) studies have suggested that combining off-pump CABG and a no-touch technique to the aorta should be the method of choice to reduce the number of microembolic hits (MES) to a minimum number [3,5]. A recent paper advocating this method has reported MES's ranging between 13 and 100 during the entire operation using TCD monitoring which is a rather low number when compared to other techniques [5]. Our findings with TCD monitoring during proximal anastomoses have shown that the number of MES's using the Enclose II device is less than side-biting clamps, which suggests that using this device may be less traumatic.

Requirements for a new proximal anastomotic device should be reproducibility, ease of use and a short anastomotic time. The device should work with either vein or artery and the proximal or distal order of anastomoses should be interchangable. It should also offer patency comparable to hand-sewn techniques [4,9]. The Enclose II device fulfills some of these requirements and can be a useful tool during off-pump CABG surgery, especially in high-risk patients where the surgeon is not willing to put a side clamp on the aorta. In such cases performing a proximal anastomoses with minimal aortic manipulation may not only result in a lower rate of embolism or dissection but can also reduce the rate of incomplete revascularisation. The authors' experience with the device is limited to 49 anastomoses. Only multi-center studies with higher volume of patients will show the benefits and possible pitfalls of this device. Nevertheless, our clinical experience was encouraging.


   References
Top
 Abstract
 1. Introduction
 2. Material and methods
 3. Results
 4. Discussion
 References
 

  1. Blauth CI, Cosgrove DM, Webb BW, Ratliff NB, Boylan M, Piedmonte MR, Lytle BW, Loop FD. Atheroembolism from the ascending aorta: an emerging problem in cardiac surgery. J Thorac Cardiovasc Surg 1992;103:1104-1112.[Abstract]
  2. Barzilai BB, Marshell WG, Saffitz JE, Kouchoukos N. Avoidance of embolic complications by ultrasound characterization of the ascending aorta. Circulation 1989;80:1275-1279.
  3. Chavanon O, Carrier M, Cartier R, Hebert Y, Pellerin M, Page P, Perrault LP. Increased incidence of acute ascending aortic dissection with off-pump aorta-coronary bypass surgery?. Ann Thorac Surg 2001;71:117-121.[Abstract/Free Full Text]
  4. Carrel TP, Eckstein FS, Englberger L, Berdat PA, Schmidcal J. Clinical experience with devices for facilitated anastomoses in coronary artery bypass surgery. Ann Thorac Surg 2004;77:1110-1120.[Abstract/Free Full Text]
  5. Abu-Omar Y, Cifelli A, Matthews PM, Taggart T. The role of microembolism in cerebral injury as defined by functional magnetic resonance imaging. Eur J Cardiothorac Surg 2004;26:586-591.[Abstract/Free Full Text]
  6. Eckstein FS, Bonilla LF, Englberger L, Stauffer E, Berg TA, Schmidli J, Carrel TP. Minimizing aortic manipulation during OPCAB using the symmetry aortic connector system for proximal vein graft anastomoses. Ann Thorac Surg 2001;72:995-998.
  7. Endo M, Nishida H, Tomizawa Y, Kasanuki H. Benefit of bilateral over single internal mammary artery grafts for multiple coronary artery bypass grafting. Circulation 2001;104:2164-2170.[Abstract/Free Full Text]
  8. Lytle BW, Loop FD. Superiority of bilateral internal thoracic artery grafting: it's been a long time comin. Circulation 2001;104:2152-2154.[Free Full Text]
  9. Wolf RK. Anastomotic devices for coronary surgery. Minim Invasive Ther Allied Technol 2004;13(1):4-10.
  10. Carrel TP, Eckstein FS, Englberger L, Windecker S, Meier B. Pitfalls and key lessons with the symmetry proximal anastomotic device in coronary artery bypass surgery. Ann Thorac Surg 2003;75:1318-1321.[Abstract/Free Full Text]



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