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Ann Thorac Surg 2006;81:90-96
© 2006 The Society of Thoracic Surgeons
a Department of Cardiac Surgery, Heartcenter, University of Leipzig, Leipzig, Germany
b Department of Cardiac Surgery, Cardiocentro Ticino, Lugano, Switzerland
c Department of Cardiac Surgery, Heart Center Dresden, Dresden, Germany
d Department of Cardiovascular and Thoracic Surgery, Klinikum Braunschweig, Braunschweig, Germany
e Department of Cardiovascular Medicine, Stanford University, Palo Alto, California
Accepted for publication June 8, 2005.
* Address correspondence to Dr Gummert, University of Leipzig, Heartcenter, Department of Cardiac Surgery, Strümpellstr 39, D-04289 Leipzig, Germany (Email: gumj{at}medizin.uni-leipzig.de).
Presented at the Poster Session of the Forty-first Annual Meeting of The Society of Thoracic Surgeons, Tampa, FL, Jan 24–26, 2005.
| Drs Demertzis and Harringer disclose that they have a financial relationship with Cardica.
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Abstract |
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METHODS: Fifty-four patients awaiting elective coronary artery bypass graft surgery were enrolled. Outcome variables were intraoperative device performance, early and 6- month angiographic graft patency, and 12-month clinical follow-up.
RESULTS: Sixty-three PAS-Port devices were deployed in 54 patients. Two deployments were unsuccessful. There were no reoperations for bleeding. Two patients died of causes unrelated to the device. Patency evaluation at discharge was performed by angiogram on 49 implants and computed tomography in 2 implants (86% follow-up). At discharge, all evaluated grafts were patent (100%) and rated Fitzgibbon A. At 6-month follow-up, there was no additional mortality; 47 implants (88% follow-up) were evaluated by angiography (Fitzgibbon O [n = 1], Fitzgibbon B [n = 1], and Fitzgibbon A [n = 45]) and 5 by computed tomography. All grafts but 1 were patent (98.1%). At 12 months, 2 additional patients died of causes unrelated to the PAS-Port implant. Forty-six of 50 alive patients (95.8%) were followed up without any reports of device-related major adverse cardiac events.
CONCLUSIONS: Discharge (100%) and 6-month patency (98%) are excellent; patency and 12 months' clinical follow-up compares favorably with data from historical hand-sewn controls. The PAS-Port system safely allows the clampless creation of a proximal anastomosis.
The concept of proximal anastomotic devices was first investigated in a canine model in 1979 [1]. The renewed interest in developing proximal anastomotic devices was triggered by the advent of off-pump coronary artery bypass grafting. Since clamping the aorta is no longer required to induce cardioplegic arrest, the next logical step was to avoid manipulating the aorta altogether by anastomosing vein grafts to the ascending aorta. Partial clamping is known for its potential for atherosclerotic embolization and aortic dissection. Other potential advantages of a proximal anastomotic connector are time savings, facilitated limited access surgery and creation of a standardized anastomosis with a predefined orifice area and consistent quality independent of between-surgeons and within-surgeon variability. Most proximal connector designs are based on expandable stentlike couplers that complete the anastomosis without the need for aortic clamping.
Recently, the Cardica PAS-Port anastomosis system (Cardica, Redwood City, CA) has been introduced to facilitate the creation of a proximal vein graft anastomoses to the aorta in coronary artery bypass graft (CABG) surgery. The PAS-Port device allows the deployment of a clampless proximal anastomosis between a vein graft and the aorta (Fig 1). The proximal anastomosis must be performed first. The specific design of the PAS-Port device avoids exposure of foreign material inside the graft and minimizes the total amount of blood exposed nonintimal surface inside the aortic lumen (Fig 2). This is illustrated by an intraluminal view of a deployed implant in cadaveric human tissue (Fig 3).
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To further demonstrate safety and functionality of the PAS-Port System, the pivotal C-Port trial was designed to allow for parallel deployments of the PAS-Port system in vein grafts not used in conjunction with the C-Port distal anastomosis system. This subset of patients comprises the PAS-Port II trial. The 6-month angiographic and 12 months clinical follow-up data are presented in this paper.
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Material and Methods |
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Patency of index grafts was evaluated by either angiography or computed tomography (CT). All angiograms and CTs were analyzed by a core laboratory not associated with the investigative sites. At 6 months postoperatively, patency of index grafts was evaluated by either angiography or CT. All these angiograms and CTs were also analyzed by a core laboratory not associated with the investigative sites.
Twelve-month clinical follow-up consisted of a clinical evaluation with resting, stress electrocardiogram, and assessment of major adverse cardiac events. A major adverse cardiac event was defined as a death, myocardial infarction, or need for target vessel revascularization.
Anastomotic Device
The PAS-Port device has a single size coupler suitable for grafts with outside diameters ranging from 4 to 6 mm. The implant is made of 316L medical grade stainless steel and contains nine barbed inner flange tines, over which the vein graft is everted during loading. The inner flange tines penetrate and secure the vein graft after deployment. The implant is initially configured in a primarily tubular state (Fig 4A). During deployment it expands and forms an inner and outer flange that secure it to the aorta (Fig 4B to F). The delivery device integrates the hole making mechanism and the implant deployment system into a single device, where one rotation of the knob completes the creation of a proximal anastomosis. The cutter system is comprised of spring-loaded cylindrical cutter, a spike used to capture the cut section of the aortic wall, and an introducer that secures the aortotomy during insertion of the implant. Saphenous vein grafts are harvested using standard techniques, except for avoiding the use of clips to occlude side branches. The inflated outer diameter of the conduit should be in the range from 4 to 6 mm with a double wall thickness, that should not exceed 1.4 mm. When loading the graft, the vein is pulled through the stainless steel implant and everted over the end of the implant. During the loading process any contact of endothelium with foreign material is avoided. The mean arterial pressure during device deployment should be between 50 mm Hg and 80 mm Hg. Removal of the adventitia or connective tissue of the aortic wall is recommended only if it is excessively thick or diseased. The initial phase of rotation of the knob at the proximal end of the delivery device initiates and completes the aortotomy. Further rotation completes the implant deployment and separation from the delivery device.
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Results |
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Seventy-eight distal anastomoses were completed, with 61 successfully deployed implants, 46 single grafts, 13 single sequential grafts, and 2 double sequential grafts. The outer diameter of the vein grafts used in conjunction with the PAS-Port device was in 15 grafts (25%) between 4.0 and 4.4 mm, in 26 grafts (42%) between 4.5 and 4.9 mm, in 19 grafts (31%) between 5.0 and 5.4 mm, and in 1 graft (2%) greater 5.5 mm. The left anterior descending artery was grafted in 4% (1.6 ± 0.5 mm target vessel), the diagonal artery was grafted in 6% (1.4 ± 0.4 mm target vessel), circumflex artery branches were grafted in 37% (1.7 ± 0.3 mm target vessel), and the territory of the right coronary artery was grafted in 53% (1.6 ± 0.6 mm target vessel). A pursestring stitch was used to secure hemostasis in 6 deployments. There were no redo operations for bleeding. Two patients (each with one PAS-Port implant) died before discharge of causes unrelated to the device. The causes of death were pneumonia resulting in adult respiratory distress syndrome in 1 patient and intraoperative right ventricular failure as a result of a preoperative acute right ventricular infarct in 1 patient. Patency of the PAS-Port grafts of these 2 patients was confirmed by angiography (n = 1) or reexploration (n = 1). Fifty patients with 59 PAS-Port devices were discharged.
Discharge Patency
Patency evaluation at discharge was performed by angiogram in 49 implants and CT in 2 implants (86% [51 of 59] follow-up). At discharge, all grafts were patent resulting in a patency of 100% (95% confidence interval: 93% to 100%). The angiographically evaluated implants were all rated Fitzgibbon A [3]. All patients who did not consent for patency evaluation were free of signs or symptoms of myocardial ischemia. The flowchart (Fig 5) illustrates the follow-up in this series.
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Six-Month Graft Patency
Of the 46 patients who returned for follow-up at 6 months, 38 patients (47 implants) were evaluated by angiography. Five PAS-Port implants in 5 additional patients were evaluated by CT scan. The 3 remaining patients (each with one PAS-Port implant) refused to undergo either an angiogram or CT procedure at their 6-month follow-up visit. These patients were asymptomatic. Thus, of the 59 implants deployed in 50 patients discharged in this study, a total of 52 implants in 43 patients were evaluated for patency at 6 months postoperatively (88% [52 of 59] of PAS-Port grafts were studied). One PAS-Port index graft was occluded (Fitzgibbon 0), resulting in a patency rate in the patients followed up by angiography of 97.9% (46 of 47 implants). One additional PAS-Port index graft had a narrowing of the graft body greater than 50% at the proximal anastomosis (Fitzgibbon B). Thus, the overall freedom of stenosis greater than 50% or occlusion of the PAS-Port index grafts evaluated by angiography at 6 months postoperative was 95.7% (45 of 47). All PAS-Port grafts evaluated by CT were found to be patent. The overall 6 months patency rate including the patients followed upby CT scan was 98.1%. In the occluded graft, the stenosis grade of the distal vessel was 50% with a target vessel size of 2.5 mm; in the Fitzgibbon B graded graft, the stenosis grade of the distal vessel was 60% with a target vessel diameter of 3.0 mm. Overall, in 22 grafted vessels, a native stenosis grade of less than 70% was observed, the average native stenosis grade was 74%.
Patency evaluation of the proximal hand-sewn vein graft anastomosis in these patients was performed in 42 anastomosis (79% follow-up) with 38 anastomoses (90.5%) rated Fitzgibbon A, 1 (2.4.%) rated Fitzgibbon B, and 3 (7.1%) rated Fitzgibbon 0.
Twelve-Month Follow-Up
At 12 months postoperatively, 2 additional patients had died of causes unrelated to the PAS-Port anastomosis (renal failure, recurrent strokes). Forty-six implanted patients returned for a compliance rate of 95.8% (46 of 50). Of these patients 89% were in Canadian Cardiovascular Society class 0 or I, 100% in New York Heart Association class I or II. None of the patients had a recent myocardial infarction or target vessel revascularization associated with an index graft (major adverse cardiac events = 0). At the time of follow-up, 76% of the patients were treated with aspirin only. In 42 implanted patients, a stress electrocardiogram was performed and 90.5% (n = 38) were negative for evidence of myocardial ischemia. This test was positive in 4 patients. In 2 patients, the leads with ischemia did not coincide with the region where the C-Port anastomosis was placed. In 1 patient, a conduction abnormality impaired the sensitivity of the electrocardiogram changes; in the remaining patient, the same pattern of ischemia had been detected in a 3-month stress electrocardiogram, and the index graft was found to be patent at 6 months. The 2 patients with unsuccessful deployments in which the PAS-Port anastomoses had been converted to hand-sewn (Fig 5) were also followed up at 12 months postoperatively. These 2 patients were well and without major adverse cardiac events at 12 months.
Take-Off Angle
The aortic take off angle of the proximal anastomosis was angiographically determined (discharge and 6-month angiogram) using the implant as the plane of reference (assessable in 52 of 59 implants and 42 of 53 hand-sewn anastomosis). The mean take-off angle of a device anastomosis was 54 ± 33 degrees; in 27% of the implants, a 90-degree take off was evident. In the hand-sewn anastomosis performed on the same patients, the mean take-off angle was 62 ± 31 degrees; and in 35%, a 90-degree takeoff angle was measured. The correlation between take off angle and anastomosis technique is negative and small: r = –0.14 and is not significant (p = 0.186).
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Comment |
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The 12-month evaluation including assessment by stress electrocardiogram and determination of major adverse cardiac events demonstrated a favorable outcome in patients after implantation of the PAS-Port system. None of the patients suffered a myocardial infarct or required a target vessel revascularization since discharge. Cheng and colleagues [4] and Unger and coworkers [5] have published data indicating the 1-year mortality was between 2.6% and 3.6%. The mortality since discharge in this study was 3.8%. The Unger group reported a myocardial infarct rate of 4.1% in more than 600 patients studied 1 year postoperatively.
Graft patency in anastomotic devices must be compared with patency in hand-sewn anastomosis. The largest meta-analysis, by Mack and colleagues, was presented at the Techno-College of the European Society of Cardiothoracic Surgery in 2004 (personal communication). This analysis, comprising more than 28,000 grafts, revealed a patency of 87.9% after less than 30 days, 84.1% at 6 months, 82.7% after 12 months, and 74.3% between 2 and 5 years. Our study results compare favorably to these data.
In the initial PAS-Port trial, 6-month patency was 87.2%, the common denominator for the occluded grafts is a less than 60% stenosis in the native coronary artery. In this study again, both the occluded graft and the stenosed graft were anastomosed to large target vessels with less than a 60% stenosis . Previously, Manninen and colleagues [6] had demonstrated the negative impact of native artery stenosis on vein graft patency. That underlines the difficulties in evaluating anastomotic devices because the reasons for graft stenosis or occlusion are multifactorial, and after the graft is found to be occluded, the probable cause can only be derived by inference. Factors that impact graft patency are the inner diameter and disease state of the target vessel, the use of single versus sequential grafts and their disease state, the amount of myocardium supplied with blood (run off), certain patient demographics such as presence of obesity and sex, and postoperative medical treatments (use of statins and antiplatelet medication). These factors must be considered when judging patency rates. Certainly, a common standard should be established to allow a more standardized comparison between different anastomotic devices.
One of the hypothetical disadvantages of anastomotic devices described in the literature is the 90-degree take-off angle [2]. It is very important to place the anastomosis on the anterior portion of the aortic wall when grafting the territory of the right coronary and to place the anastomosis as lateral as possible when grafting the left territory using anastomotic devices.
Surprisingly, in this series we were able to demonstrate angiographically that the actual take-off angle of device anastomosis and hand-sewn anastomoses are evenly distributed with no significant differences in respect to the average take-off angle and percentage of grafts departing at a 90-degree angle relative to the aortic wall surface. Only 1 of 3 of the patients have a 90-degree take off angle in both groups and the average take-off angle in the PAS-Port group is actually less than the hand-sewn group; however, the difference is not significantly different and may be driven by other factors.
The unique design of the PAS-Port implant with a low implant profile height and the outer flange elements essentially flush with the surface of the aorta allows for certain flexibility in the aortic region.
The PAS-Port device requires that the proximal anastomosis be performed before the distal anastomosis. This sequence is not routinely used by many surgeons in on-pump surgery. It is believed that it is more demanding to assess the correct length of the graft when performing the proximal anastomosis first. However, by doing the proximal anastomosis first there is immediate perfusion of the grafted territory; an important advantage, especially in off-pump surgery.
For the first-generation Symmetry device, CE Mark and Food and Drug Administration clearance were issued in May 2001, and according to the manufacturer, more than 40,000 devices have been implanted worldwide [2]. As adoption of the product increased, some conflicting reports concerning patency were published that emphasized a reduction of patency both in short and late follow-up [7–11]. The differences in the outcome of the current study and these reports may be explained by a substantial reduction in blood exposed nonintimal surface [12] and by the fact that graft loading in the PAS-Port does not result in endothelial damage of the bypass graft.
The limitation of this study is that it is not a randomized trial, with a small number of patients included. The results are very encouraging, nonetheless, and a randomized trial is currently being performed to further evaluate the device.
In summary, the midterm patency rate of the PAS-Port device is promising. In the light of reports on late graft failure for other devices, we continue to monitor all patients in this study. At 1 year after surgery, no further device-related problems have occurred. The integrated design of this product allows rapid clampless deployment, and may prove to be a valuable asset in coronary artery surgery, especially in beating-heart procedures while using vein grafts.
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Requirements for Recertification/Maintenance of Certification in 2006 |
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The American Board of Thoracic Surgery will no longer publish the names of individuals who have not recertified in the American Board of Medical Specialties directories. The Diplomate's name will be published upon successful completion of the recertification/maintenance of certification process.
The CME requirements are 70 Category I credits in either cardiothoracic surgery or general surgery earned during the 2 years prior to application. SESATS and SESAPS are the only self-instructional materials allowed for credit. Category II credits are not allowed. The Physicians Recognition Award for recertifying in general surgery is not allowed in fulfillment of the CME requirements. Interested individuals should refer to the Booklet of Information for a complete description of acceptable CME credits.
Diplomates should maintain a documented list of their major cases performed during the year prior to application for recertification. This practice review should consist of 1 year's consecutive major operative experiences. If more than 100 cases occur in 1 year, only 100 should be listed.
Candidates for recertification/maintenance of certification will be required to complete all sections of the SESATS self-assessment examination. It is not necessary for candidates to purchase SESATS individually because it will be sent to candidates after their application has been approved.
Diplomates may recertify the year their certificate expires, or if they wish to do so, they may recertify up to two years before it expires. However, the new certificate will be dated 10 years from the date of expiration of their original certificate or most recent recertification certificate. In other words, recertifying early does not alter the 10-year validation.
Recertification/maintenance of certification is also open to Diplomates with an unlimited certificate and will in no way affect the validity of their original certificate.
The deadline for submission of applications for the recertification/maintenance of certification process is May 10 each year. A brochure outlining the rules and requirements for recertification/maintenance of certification in thoracic surgery is available upon request from the American Board of Thoracic Surgery, 633 N St. Clair St, Suite 2320, Chicago, IL 60611; telephone: (312) 202-5900; fax: (312) 202-5960; e-mail: mailto:info{at}abts.org. This booklet is also published on the website: www.abts.org.
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This article has been cited by other articles:
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  J. Kempfert, U. T. Opfermann, M. Richter, T. Bossert, F. W. Mohr, and J. F. Gummert Twelve-month patency with the PAS-port proximal connector device: a single center prospective randomized trial. Ann. Thorac. Surg., May 1, 2008; 85(5): 1579 - 1584. [Abstract] [Full Text] [PDF]
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W. J.L. Suyker and C. Borst Coronary connector devices: analysis of 1,469 anastomoses in 1,216 patients. Ann. Thorac. Surg., May 1, 2008; 85(5): 1828 - 1836. [Abstract] [Full Text] [PDF]
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 J. Wippermann, C. Konstas, M. Breuer, H. Kosmehl, T. Wahlers, and J. M. Albes Long-term effects in distal coronary anastomoses using different adhesives in a porcine off-pump model. J. Thorac. Cardiovasc. Surg., August 1, 2006; 132(2): 325 - 331. [Abstract] [Full Text] [PDF]
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