Ann Thorac Surg 2005;80:1091-1095
© 2005 The Society of Thoracic Surgeons
New technology
Evaluation of the Enclose Proximal Anastomosis Device in Coronary Artery Bypass Grafting
Sary F. Aranki, MD
*
,
Prem S. Shekar, MD,
Afshin Ehsan, MD,
Margaretta Byrne-Taft, MPH,
Gregory S. Couper, MD
Division of Cardiac Surgery, Brigham and Women’s Hospital, Boston, Massachussetts
Accepted for publication October 22, 2004.
* Address reprint requests to Dr Aranki, Brigham and Women’s Hospital, 75 Francis St, Boston, MA 02115. (Email: saranki{at}partners.org).
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Abstract
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PURPOSE: Minimal manipulation of the ascending aorta during coronary artery bypass grafting may reduce the incidence of adverse perioperative events related to atheroembolic events. The objective of this study was to evaluate a new proximal anastomotic device (Novare Enclose device [Novare Surgical Systems, Cupertino, CA]).
DESCRIPTION: Over a 23-month period, a total of 76 proximal anastomoses were performed in 50 patients (40 males and 10 females; mean age, 74.36 years). In 45 patients, the proximal anastomosis was constructed before the distal (25 off-pump and 20 on-pump), and in 5 patients the proximal anastomosis was constructed on cardiopulmonary bypass because of diseased ascending aortas.
EVALUATION: The average time per anastomosis was <8 minutes. There were no device related complications. There were no atheroembolic complications in this cohort of patients. One patient underwent cardiac catheterization postoperatively, and the proximal vein anastomosis in this patient was widely patent.
CONCLUSIONS: The Novare Enclose proximal anastomotic device (Novare Surgical Systems) appears to be safe and effective as a tool for proximal anastomosis within a reasonable time period and is comparable with accepted techniques.
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Introduction
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Manipulation of the ascending aorta during construction of the proximal anastomosis in coronary artery bypass grafting (CABG) can lead to atheroembolism from obvious or occult atherosclerotic disease that may result in major morbidities [1].
The evolution of off-pump CABG in recent years has led to the development of various distal and proximal anastomotic devices. Thus far, proximal anastomotic devices have generated most interest because of reduced aortic manipulation as compared with a partial occluding side clamp. There are three commonly used proximal anastomotic devices. The first to be introduced was the sutureless St. Jude Symmetry device (St Jude Medical Inc, St. Paul, MN). The other two devices are the Novare Enclose proximal anastomotic device (Novare Surgical Systems, Cupertino, CA) and the Guidant Heart String proximal anastomotic device (Guidant Medical Inc, Indianapolis, IN), which are both designed to mimic a partial occluding side clamp but without tangential force being applied on the aorta. The Novare Enclose device (Novare Surgical Systems) can be used for multiple anastomoses, whereas all others are for single use.
We report on our preliminary experience with the Novare Enclose device (Novare Surgical Systems) with particular emphasis on safety and efficacy. In addition, technical details are discussed to help shorten the learning curve for first-time users.
Over a 23-month period ending February 2004, a total of 1,083 patients underwent CABG. In 50 patients (4.6%), the proximal anastomoses were constructed using the Novare Enclose device (Novare Surgical Systems). These included some off-pump CABG patients and the rest were on-pump CABG patients who were randomly chosen, including most who had severe unclampable posterior atherosclerotic disease of the ascending aorta who would have otherwise required hypothermic circulatory arrest. Epiaortic scanning was used to look for aortic atherosclerotic disease.
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Technology
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The Brigham and Women’s Hospital Institutional Review Board approved this study (Protocol No. 2003-P-01178/1, Brigham and Women’s Hospital).
The Novare Enclose device (Novare Surgical Systems) (Fig 1
center) consists of two parallel horizontal arms connected by a perpendicular, rectangular-shaped plastic housing. The lower arm is fixed in position, but its distal tip can open into a diamond shaped membrane by turning a lever attached to the side of the plastic housing. In the newer lower profile Novare Enclose II model (Novare Surgical Systems), a knob located on the superior aspect and operated by a special driver has replaced this lever and the membrane is set lower to preclude injury. The back end of this arm is connected to plastic tubing with a plastic stopper at its end. This plastic tubing is connected to a metal bar inside the lower arm, which lies on top of the membrane and acts as a scaffold. In addition, there are two tiny holes on the superior aspect of this metal bar that allows blood to flow back to the attached plastic tubing. The upper arm is mobile. Its distal end divides into two fork-like, diamond-shaped curved metal arms. The proximal end of the upper arm is attached to the plastic housing through a pivot and can be raised or lowered by means of a control knob at the superior aspect of the plastic housing. This allows the aortic wall at the site of the proximal anastomosis to be sandwiched between the two arms, thus achieving a bloodless field when a punch hole is made for the proximal anastomosis.
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Fig 1. (A–G) Step by step use of the Novare Enclose device (Novare Surgical Systems, Cupertino, CA) for construction of the proximal anastomosis with device description.
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Technique
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In all patients except 5, the proximal anastomoses were constructed first before the distals. The mean arterial pressure was maintained around 60 mm Hg. The proposed sites of the proximal anastomoses are identified and marked on the ascending aorta and the site of entry of the device is marked equidistant from these spots to allow for easy manipulation of the device. A pursestring suture is applied at this point with 4-0 Prolene (Ethicon, Somerville, NJ), and a needle puncture made with a 14-guage needle is provided (Fig 1A). The lower arm is inserted into the aorta through this needle hole and the device is maneuvered into position over the proposed site of anastomosis (Fig 1B). The device is deployed by opening the diamond-shaped membrane at the tip of the lower arm (Fig 1C). The upper arm on the outside of the ascending aorta is lowered into place until a watertight seal is achieved (Fig 1D). This is indicated by no blood returning through the small plastic tubing.
A punch hole is then made by using a size 15 blade making a small cut perpendicular to the small metal bar overlying the membrane (Fig 1E). It is important that the incision in the aortic wall encompasses the full thickness of the aorta. This is indicated by seeing the metal bar through the incision. Because the two arms of the device stretch the aortic wall, a size 3.6-mm punch is adequate to create an optimal punch hole. It is imperative that the punch is inserted through the aortic incision against the metal bar and maneuvered into place to make a clean cut encompassing all layers of the aortic wall (Fig 1F). The anastomosis is then performed using the parachute technique with 6-0 Prolene (Ethicon) (Fig 1G).
In cases requiring multiple proximal anastomoses, the device is then released by elevating the upper arm and maneuvering it into the second position. Otherwise the device is taken out after reversing the deployment process and extracted from the aorta. The 4-0 Prolene suture (Ethicon) is tied down around the entry site in the aorta.
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Clinical Experience
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Baseline Characteristics
A total of 76 proximal anastomoses were constructed in 50 patients (1.52 ± 0.5 anastomosis per patient). There were 40 males and 10 females with a mean age of 74.36 years. In 25 patients, the CABG was done on-pump. The proximal anastomosis was constructed after full heparinization and cannulation, but before the initiation of CPB. In 5 patients with severe and unclampable posterior atherosclerotic disease of the ascending aorta, the distal anastomoses were performed first on hypothermic fibrillatory arrest and the proximals were constructed thereafter. Our alternative practice would have been total circulatory arrest during which the proximal anastomosis was constructed. In the remaining 25 patients, the CABG was done off-pump. The proximal anastomosis was constructed before the distal. Table 1
summarizes our experience with the Novare Enclose device (Novare Surgical Systems).
Operative Variables
Figure 2
summarizes our learning experience of using the Novare Enclose device (Novare Surgical Systems). Overall, the setup time for the device was 4.20 ± 1.40 minutes. The mean time for the first proximal anastomosis was 8.32 ± 2.75 minutes and the second proximal anastomosis was 7.12 ± 1.54 minutes.
Device-Related Complications
Anticipated device-related complications could have arisen from trauma to the aorta during insertion and deployment of the device, resulting in aortic rupture, aortic dissection, and atheroembolism. None of the patients in this study had any of these complications. Atheroembolism, which is most important, can manifest with cerebral, gastrointestinal, renal, or limb ischemia. None of the patients had any ischemic complications.
Nondevice-Related Complications
One patient in the off-pump group died from undiagnosed preoperative metastatic hepatic malignancy. There were no strokes in this cohort of patients. Other complications such as sternal wound breakdown that needed rewiring occurred in 1 patient, 2 patients had nonischemic gastrointestinal complications develop that required exploratory laparotomy, 2 patients had respiratory insufficiency develop that required a tracheostomy, 1 patient had oliguric renal failure that recovered with time, and 2 patients had nonischemic heart failure.
Technical Failures
There were three technical failures early in our experience (ie, the first 10 patients) due to membrane rupture caused by the needle in 2 patients and a size 11 blade in 1 patient. In all of these patients, a new device was used. As a result, we altered our anastomotic technique to the parachute technique and began using a size 15 blade for aortotomy, which cannot reach the membrane due to the presence of the metal bar.
In 1 patient there was bleeding from the heel of the anastomosis due to a loose suture. Attempts to repair this failed and it had to be reconstructed using a partial occluding clamp.
Angiographic Follow-Up
The vein graft was widely patent in 1 off-pump CABG patient who required an angiogram for possible graft failure (Fig 3). None of the other patients were followed up by angiography.
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Comment
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The last 50 years has seen many advances in device technology in cardiac surgery. In CABG, the evolution of distal anastomotic stabilizers has allowed off-pump CABG to become a reproducible reality. The introduction of proximal anastomotic devices happened later [2], and the various models on the market are being currently tested for safety and efficacy.
The partial occluding clamps used for proximal anastomoses has been the gold standard. The potential danger of these clamps has been recognized as being related to mechanical trauma, especially in diseased aortas with atheroembolic potential with devastating neurologic and systemic outcomes [1, 3]. One emerging trend has been toward the single-clamp technique to avoid the partial occluding clamps [4]. As the off-pump CABG became increasingly popular, alternative devices to the partial occluding clamps were introduced.
The complex sutureless St Jude Symmetry device (St Jude Medical Inc) has been well tested. It can only be used once per anastomosis and before the construction of the distal anastomosis [5]. The results of using this device have been mixed [6–9].
The Guidant Heart String system (Guidant Medical Inc) has been recently introduced. Its design allow for a proximal suture anastomosis, whereas a specially designed string (shaped like an inverted umbrella) is deployed inside the aorta allowing for a bloodless field during anastomosis [10].
When we first considered using the Novare device (Novare Surgical Systems), we had concerns about introducing the stiff lower jaw into the ascending aorta and moving it around to perform multiple anastomoses. We were also concerned about the separate puncture hole to introduce the device and the potential for bleeding or dissection, or both. We elected to use this device in on-pump CABG cases after heparinization and cannulation, but before CPB in order to deal immediately with any complications. Apart from the three ruptured membranes, we had no serious complications such as aortic rupture, dissection, or anastomotic dehiscence. Once we felt comfortable with the use of this device, we started using it more for off-pump CABG. We also used it on 5 patients with severe atherosclerotic disease of the posterior ascending aorta where a cross clamp could not be applied. We believe that avoiding circulatory arrest otherwise required in these patients may contribute to reducing perioperative morbidity.
The learning curve for the proper use of this device is not steep. Making the appropriate punch hole is the most challenging aspect because the device stretches the aorta. We learned that using a smaller punch will create an optimal hole. It is important to cut down until the metal bar in the lower jaw is seen. Once these challenges were understood, performance of the anastomosis using the parachute technique is simple. Consequently, training the residents and fellows on the use of this device is more efficient than with other devices.
In conclusion, the Novare Enclose proximal anastomotic device (Novare Surgical Systems) is a safe and efficacious for use during CABG, especially in special situations in which the aorta is unclampable because of posterior wall disease. The anastomoses are easily reproducible, the learning curve is acceptable and the procedure can be taught to residents in training.
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Disclosures and Freedom of Investigation
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This study was funded by the Division of Cardiac Surgery at Brigham and Women’s Hospital. The devices used were purchased by the hospital as this is an approved Food and Drug Administration device. The authors had full control of the design of this study, methods used, outcome measurements, analysis of data, and production of the written report.
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Disclaimer
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The Society of Thoracic Surgeons, the Southern Thoracic Surgical Association, and The Annals of Thoracic Surgery neither endorse nor discourage use of the new technology described in this article.
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References
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- Barbut D, Hinton RB, Szatrowski TP, et al. Cerebral emboli detected during bypass surgery are associated with clamp removal Stroke 1994;25(12):2398-2402.[Abstract]
- Calafiore AM, Bar-El Y, Vitolla G, et al. Early clinical experience with a new sutureless anastomotic device for proximal anastomosis of the saphenous vein to the aorta J Thorac Cardiovasc Surg 2001;121:854-858.[Abstract/Free Full Text]
- Sylivris S, Levi C, Matalanis G, et al. Pattern and significance of cerebral microemboli during coronary artery bypass grafting Ann Thorac Surg 1998;66:1674-1678.[Abstract/Free Full Text]
- Aranki SF, Sullivan TE, Cohn LH. The effect of the single aortic cross-clamp technique on cardiac and cerebral complications during coronary bypass surgery J Card Surg 1995;10(Suppl 4):498-502.[Medline]
- Scarborough JE, White W, Derilus FE, et al. Combined use of off-pump techniques and a sutureless proximal aortic anastomotic device reduces cerebral microemboli generation during coronary artery bypass grafting J Thorac Cardiovasc Surg 2003;126:1561-1567.[Abstract/Free Full Text]
- Katariya K, Yassin S, Hassan Y, et al. Initial experience with sutureless proximal anastomoses performed with a mechanical connector leading to clampless off-pump coronary artery bypass grafting Ann Thorac Surg 2004;77:563-568.[Abstract/Free Full Text]
- Reuthebuch O, Kadner A, Lachat M, et al. Early bypass occlusion after deployment of nitinol connector devices J Thorac Cardiovasc Surg 2004;127:1421-1426.[Abstract/Free Full Text]
- Dewey TM, Crumrine K, Herbert MA, et al. First year outcomes of beating heart coronary artery bypass grafting using a proximal mechanical connector Ann Thorac Surg 2004;77:1542-1549.[Abstract/Free Full Text]
- Okada K, Sueda T, Orihashi K, et al. Early type A dissection with the aortic connector device Eur J Cardiothorac Surg 2004;25(5):902-904.[Abstract/Free Full Text]
- Medalion B, Meirson D, Hauptman E, et al. Initial experience with the Heartstring proximal anastomotic system J Thorac Cardiovasc Surg 2004;128:273-277.[Abstract/Free Full Text]
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Abstract
Introduction
= first proximal time; pink 
= second proximal time; yellow 
= set-up time.)