Long term angiographic monitoring reveals safety and efficacy of the Converge end-to-side anastomotic coupler
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《血管的通路杂志》
a Division of Thoracic and Cardiovascular Surgery, Hannover Medical School, Carl Neuberg Str. 1, 30625 Hannover, Germany
b Division of Cardiovascular Surgery, University Hospital Schleswig-Holstein, Kiel, Germany
Abstract
Sutureless anastomotic systems promise to minimize surgical trauma during revascularization procedures. We evaluate graft patency following end-to-side coupling with the Converge device. Fifteen of 35 enrolled patients of a two-center, non-randomized clinical study underwent 2-year angiography and clinical follow up, after sutureless anastomotic coupling of one of the grafts, using the Converge system. Fifteen anastomoses with the Converge system and 38 ‘manual’ anastomoses were performed. Mean patient age was 65.9±8.6 years (13 male, 1 female). Mean ejection fraction (EF) was 60.6±10.2%. Mean follow-up period was 1.8±0.4 years. Device-related adverse events, such as excessive hemorrhage, thromboembolic complications, perianastomotic leak, infarction and device failure, leading to explantation or death were followed clinically. One patient (1/15) displayed an occluded venous graft to an obtuse marginal branch. All other Converge anastomoses were patent. The challenging or laborious anastomoses and low anastomotic flow (at operation) did not correlate with morphological obstruction at angiography. No other adverse effects were noted. The Converge sutureless anastomotic coupler fashions safe graft-to-coronary anastomoses which exhibit adequate patency at the 2-year follow-up time point. This system might offer a favorable anastomotic option in the expanding fields of minimal invasive, off-pump and endoscopic surgery.
Key Words: Coronary disease; Anastomosis; Revascularization
1. Introduction
The long-term outcome of coronary revascularization procedures stands and falls with the patency of the grafts. The functionality of hand-sewn grafts, still state of the art at the present time, is largely dependent on the surgeons' individual skills, tremor, vision, and state of fitness or exhaustion. Failure at the aortic anastomosis site, for instance, can be caused by deep bites into the vein which might result in an obstruction at the neck of the proximal anastomosis. Inadequate bites in the proximity of the heel or toe of the distal anastomosis may obstruct blood flow and cause occlusive thrombosis of the lumen. A visually adequate hand-sewn anastomosis may conceal irregularities at the heel and toe sites and occlude in the further postoperative course [1].
A series of devices capable of fashioning venous-to-coronary anastomoses have been introduced to achieve this goal [2–8]. All of them exhibit benefits and limitations pertaining to handling, physical properties, and functional merit compared to the surgeons' manual dexterity. Ultimately, the decisive endpoint of utilizing such coupling devices is graft patency in the long term, which can be best assessed by angiography or MRI [9–14]. However, in most of the cases, angiographic outcome of the automatically tailored anastomoses has not been evaluated systematically and has not been presented other than in brief communications. Heterogenic reports derived from anecdotal case presentations render carefully designed studies inexorable for the further evolution of these novel techniques.
Converge Medical (Sunnyvale, CA) has developed a proprietary system to produce a rapid, precise sutureless anastomosis. The device relies on a series of concentric mating anastomotic frames which tie the anastomotic halves together by clamping them. Fig. 1A shows a schematic intraoperative view of the mating system for the generation of the anastomosis. The Converge Medical, Inc. Sutureless anastomotic system produces a unique lumen geometry with high precision and eliminates suture constriction or other irregularities which are not unusual following hand-fashioned anastomosis. Because of its design, the Coverge SAS results in a consistent flow-line pattern which cannot be reproduced consistently with standard suturing techniques. Sutures create discrete points of stress in tissue and can be the prime determinate of anastomotic biomechanics. A more homogenous distribution of anastomotic stress can be achieved by the Converge clamping-coupler. By fixing the frames in place, anastomotic healing can occur. In the present angiographic study we examine the 2-year patency of suturelessly produced anastomoses and discuss the capacity of the Converge-system to eliminate the need for manually sutured anastomoses.
2. Patients and methods
Thirty-three patients with advanced coronary artery disease enrolled in a two-center, non-randomized study and underwent sutureless anastomotic coupling with the Converge device. The enrollment and patient informed consent were realized in compliance with our institution's Ethics Committee regulations and following approval. At the time of presentation for follow-up coronary angiography, history for postoperative symptomatology was obtained, including chest pain, shortness of breath, physical load until symptoms begin, and bleeding from various sources. The sutureless anastomoses were only venoarterial. The device is not yet refined to perform a delicate arterioarterial anastomosis. Exclusion criteria were severely sclerotic and calcified coronaries, tandem stenoses, too small or fragile-appearing vessels, or vessels with an inadequate flow distribution area. Also, intramuscular segments were excluded as a potential anastomotic target. Patients with multiple-stented target coronaries were also excluded. Patients with multiple-stented target coronaries were also excluded. From these patients a total of 15 consented to angiographic monitoring and underwent follow-up catheterization for the evaluation of patency of the coupled grafts, between 19 and 27 months after operation.
Patient mean age was 65.9±8.6 years at follow up. Thirteen male and two female patients underwent long term angiography. Mean left ventricular ejection fraction (EF) was 60.6±10.3%. Preoperative myocardial infarction was known in 38.4% of the subjects involved. None of the patients suffered of heart failure at the time of operation. As many as 77% of the patients had hyperlipidemia, 69.2% had hypertension and 15.4% had diabetes. The mean follow-up time was 1.8±0.4 years (Table 1).
The coupler system consists of a set of concentric mating anastomotic frames that clamp vessel ends together to promote anastomotic healing. The basic mechanism of the Converge device utilizes two nickel-titanium alloy (Nitinol) frames which capture and stabilize the vein and coronary vessel margins in a predefined position (Fig. 1B), [www.convergemed.com/technology.html]. Every CABG procedure involved one singular sutureless Converge anastomosis. The mean size of the target vessel destined for sutureless anastomosis was 3–4 mm in 69%, and between 2–2.5 mm in 31% of the cases. The first diagonal branch of the left coronary artery was the target in 6 of 15 cases. The right coronary artery was anastomosed in 5 of 15 patients, the circumflex artery in 1 of 15 patients and obtuse marginal branches in 3 of 15 patients. The cumulative number of anastomoses (including the hand-sewn ones) per patient was 3.7±0.6. Blood flow over the mechanical anastomosis was measured after Converge coupling using a transit time method with a 3-mm ultrasonic flow probe (HT-313 Flow meter, Transonic Systems Inc). Coupled anastomosis flow ranged from 23 to 92 ml/min and averaged at 57.8±10.2 ml/min. Duration of operation was 218±27.6 min. Mean cross clamp time was 39.4±9.2 min. Loading time of the coupler was 435±105 s. The anastomotic time for the sutureless anastomosis using the Converge system was 118.3±48.9 s. The cumulative postoperative blood loss was 680.8±270.4 ml. The maximal values for serum Creatine Kinase (CK) was 784±186 IU/ml, those for the isoenzyme CK-MB averaged at 26.4±9.1 IU/ml (Table 2). In 58% of the cases the anastomotic coupling was carried out without any difficulty. In 16% of the cases coupled anastomosis was laborious, in particular with problematic visualization of the heel or toe of the anastomosis following its accomplishment. Three of the anastomoses required modification, two with a suture and one with glue.
3. Results
Postoperative follow-up coronary angiographies were uneventful and successful in identifying the coupled vein-to-graft anastomosis (Fig. 2). In the hand-sewn anastomoses the angiographic morphology was as follows: in one patient, a sequential vein graft supplying a marginal branch of the left coronary artery and the RIVP was occluded. In another patient, a hand-sewn LIMA-on-LAD anastomosis was significantly obstructed (75%). No postoperative infarction or severe angina was reported by these patients. The coupled anastomosis was patent in both patients.
One single Converge-fashioned anastomosis to an obtuse marginal branch of the circumflex artery was occluded. There was no correlation of this finding to postoperative enzyme elevation or postoperative symptomatology. In addition, the occurrence of the occlusion did not correlate with low anastomotic flow, as measured intraoperatively, in this patient. All other grafts (14/15 captured with angiographic follow-up) were patent. The patient who required additional hand-made sutures for hemostasis did not exhibit unfavorable anastomotic morphology. Also, anastomotic and loading times did not correlate with angiographic outcome. Of the 38 cumulative hand-sewn venous graft anastomoses, four exhibited occlusion (10.5%).
4. Discussion
The low incidence of anastomotic occlusion underlines the efficacy and consistency of the anastomoses carried out using the Converge coupler. The lack of adverse effects associated with the use of the Converge anastomotic coupler renders this novel method safe and efficient for coronary revascularization.
Of note, the target coronary arteries which were subjected to the Converge coupling device, had a larger average diameter compared to the hand-sewn ones and were selected intraoperatively. A minimum of 2 mm in diameter is suitable for the automated coupling device. Therefore, a direct comparison between conventional and coupled anastomoses is not feasible at this point. However, a 93% patency at 2 years constitutes a consistent anastomotic performance compared to reported patency rates between 91% [11] and 95% [12] at 3 months, 88.3% at 1 year [13], and 95% at 5 years [14] for vein grafts, respectively. We must state that with approximately 50% of the patients dropping out, this percentage represents a fraction of the maximally obtainable results. The longevity of an initially patent anastomosis presupposes delicate handling of the approximated tissues, protection of the endothelium, optimal alignment for luminal tissue contact, precise suture lines, appropriate placement of the distal anastomoses to achieve adequate flow conditions and minimization of surgical trauma. These precautionary techniques are decisive for the success of a CABG procedure but are largely dependent on individual parameters. By circumventing manual parameters, such as tremor and experience by using the coupler, a symmetric and homogenous adaptation can be achieved. Furthermore, the 30° end-to-side anastomosis angle achieved by the Converge coupler may prevent exaggerated shear stress at the site of anastomosis and facilitate smooth inflow with minimal flow turbulence. Nevertheless, anastomotic obstruction and thrombosis [15] cannot be excluded, due to rheological factors or strut misalignment and device dysfunction. The latter was not observed in our patient group, as far as anastomotic leakage is concerned.
A potential disadvantage of the device might be the clip mechanism which fixes the anastomotic ends in place which may cause endothelial trauma in the case of extensive manipulation and relocation attempts. Furthermore, the intramural stress within the coupled walls of the saphenous grafts, as well as the coronary artery, could eventually be excessive and inhibit healing processes. The optimal range of anastomotic strength which guarantees persistence of the anastomotic stability cannot be derived from angiographic examinations. In some, strongly magnified angiographic figures of the Converge-anastomosis to the right coronary artery, a vertical view of the coupler shape and alignment to the anastomosed vessels can be obtained. The device's shape appears distorted and obliquely projected on vein-to-left coronary grafts, so that neither morphological information about the quality of the anastomotic lumen can be safely obtained, nor can prognostic statements be made. Part of the challenge is the fact that the Coupler has an internal frame and an external frame which create an image artifact. Getting a flow path image is challenging and difficult, but since these devices are novel, an appropriate protocol for examining their performance with angiography has not been developed yet.
The mere presence of a metal frame or its geometry in the bloodstream may give rise to degenerative changes in the intima. More profound experience as to the progression stages of obstruction in the lumen of the sutureless anastomosis, eventually through intravascular ultrasound techniques, may provide impetus for corrective modifications. Cost-effectiveness is a further prominent issue pertaining to the use of the entire array of anastomotic devices at the present time and constitutes a decisive factor for the recruitment of larger patient populations. The latter aspect is of utmost importance for the better definition of the surgical application of the Converge (and also other anastomotic devices) coupler and the expansion of the spectrum of indications to smaller vessels or port access, and endoscopic cardiac surgery approaches. Of note, we have used veins only for the Converge anastomoses. The system has to prove itself for arterial anastomoses as well, in order to maintain the option of utilization in patients who are scheduled for total arterial revascularization. Furthermore, more accurate morphological or functional results may have been obtained with the use of angio-CT or cine-MRT, both eligible for scanning Nitinol stents. Even though a single-plane angiographic image may not be entirely conclusive, images from multiple orientations would solve the problem.
4.1. Limitations of the study
We are surprised by the reluctance of some patients to make themselves available and cannot explain the dropouts, other than the unnecessary appearing additional catheterization. Those who were co-operative underwent a short, basic angiography for morphological evaluation, and no core-lab or TIMI conditions were applied.
In summary, the Converge anastomotic device is a reliable tool for the accomplishment of consistently patent anastomoses, as evaluated by mid-term angiography. Multicenter, randomized studies are expected to expedite the process of eventual improvements and provide comparative conclusions over the traditional, manual anastomotic practice.
References
Klima U, Falk V, Maringka M, Bargenda S, Badack S, Moritz A, Mohr F, Haverich A, Wimmer-Greinecker G. Magnetic vascular coupling for distal anastomosis in coronary artery bypass grafting: a multicenter trial. J Thorac Cardiovasc Surg 2003;126:1568–1574.
Eckstein FS, Bonilla LF, Englberger L, Eberli F, Windecker S, Berg TA, Romanens M, Immer FF, Carrel TP. First clinical results with a new mechanical connector for distal coronary artery anastomoses in CABG. Circulation 2002;106:I-1–I-4.
Niinami H, Takeuchi Y, Ichikawa S, Ban T, Higashita R, Suda Y, Suzuki S. Coronary artery bypass-grafting using interrupted anastomosis with the U-clip. Kyobu Geka 2001;54:1003–1006.
Tozzi P, Stumpe F, Ruchat P, Marty B, Corno AF, von Segesser LK. Preliminary clinical experience with the Heartflo anastomosis device. Thorac Cardiovasc Surg 2001;49:279–82.
Gundry SR, Black K, Izutani H. Sutureless coronary artery bypass with biologic glued anastomoses: preliminary in vivo and in vitro results. J Thorac Cardiovasc Surg 2000;120:473–477.
Carrel T, Englberger L, Keller D, Windecker S, Meier B, Eckstein F. Clinical and angiographic results after mechanical connection for distal anastomosis in coronary surgery. J Thorac Cardiovasc Surg 2004;127:1632–1634.
Calafiore AM, Bar-El Y, Vitolla G, Di Giammarco G, Teodori G, Iaco AL, Dalessandro SD, Di Mauro M. Early clinical experience with a new suture-less anastomtic device for proximal anastomosis of the saphenous vein to the aorta. J Thorac Cardiovasc Surg 2001;121:854–858.
Eckstein FS, Bonilla LF, Englberger L, Immer FF, Berg TA, Schmidli J, Carrel TP. The St Jude Medical symmetry aortic connector system for proximal vein graft anastomoses in coronary artery bypass grafting. J Thorac Cardiovasc Surg 2002;123:777–782.
Carrel TP, Eckstein FS, Englberger L, Berdat PA, Schmidli J. Clinical experiences with devices for facilitated anastomoses in coronary artey bypass surgery. Ann Thorac Surg 2004;77:1110–1120.
Riess FC, Helmold H, Hilfer I, Bader R, Stripling J, Loewer C, Wesner F, Bleese N. Clinical experience with the cor link device for proximal anastomosis of the saphenous vein to the aorta: a clinical, prospective, and randomized study. Heart Surg Forum 2002;5:345–353.
Lingaas PS, Hol PK, Lundblad R, Rein KA, Tonnesen TI, Svennevig JL, Hauge SN, Vatne K, Fosse E. Clinical and angiographic outcome of coronary surgery with and without cardiopulmonary bypass: a prospective randomized trial. Heart Surg Forum 2003;7:115–122.
Khan NE, De Souza A, Mister R, Flather M, Clague J, Davies S, Collins P, Wang D, Sigwart U, Pepper J. A randomized comparison of off-pump and on-pump multivessel coronary-artery bypass surgery. N Engl J Med 2004;350:21–28.
Kim KB, Lim C, Chae IH, Oh BH, Lee MM, Park YB. Off-pump coronary artery bypass may decrease the patency of saphenous vein grafts. Ann Thorac Surg 2001;72:S1033–S1037.
Tatoulis J, Buxton BF, Fuller JA. Patencies of 2127 arterial to coronary conduits over 15 years. Ann Thorac Surg 2004;77:93–101.
Reuthebuch O, Kadner A, Lachat M, Kumzli A, Schurr UP, Turina MI. Early bypass occlusion after deployment of Nitinol connector devices. J Thorac Cardiovasc Surg 2004;127:1421–1426.(Uwe Klima, Theo Kofidis, )
b Division of Cardiovascular Surgery, University Hospital Schleswig-Holstein, Kiel, Germany
Abstract
Sutureless anastomotic systems promise to minimize surgical trauma during revascularization procedures. We evaluate graft patency following end-to-side coupling with the Converge device. Fifteen of 35 enrolled patients of a two-center, non-randomized clinical study underwent 2-year angiography and clinical follow up, after sutureless anastomotic coupling of one of the grafts, using the Converge system. Fifteen anastomoses with the Converge system and 38 ‘manual’ anastomoses were performed. Mean patient age was 65.9±8.6 years (13 male, 1 female). Mean ejection fraction (EF) was 60.6±10.2%. Mean follow-up period was 1.8±0.4 years. Device-related adverse events, such as excessive hemorrhage, thromboembolic complications, perianastomotic leak, infarction and device failure, leading to explantation or death were followed clinically. One patient (1/15) displayed an occluded venous graft to an obtuse marginal branch. All other Converge anastomoses were patent. The challenging or laborious anastomoses and low anastomotic flow (at operation) did not correlate with morphological obstruction at angiography. No other adverse effects were noted. The Converge sutureless anastomotic coupler fashions safe graft-to-coronary anastomoses which exhibit adequate patency at the 2-year follow-up time point. This system might offer a favorable anastomotic option in the expanding fields of minimal invasive, off-pump and endoscopic surgery.
Key Words: Coronary disease; Anastomosis; Revascularization
1. Introduction
The long-term outcome of coronary revascularization procedures stands and falls with the patency of the grafts. The functionality of hand-sewn grafts, still state of the art at the present time, is largely dependent on the surgeons' individual skills, tremor, vision, and state of fitness or exhaustion. Failure at the aortic anastomosis site, for instance, can be caused by deep bites into the vein which might result in an obstruction at the neck of the proximal anastomosis. Inadequate bites in the proximity of the heel or toe of the distal anastomosis may obstruct blood flow and cause occlusive thrombosis of the lumen. A visually adequate hand-sewn anastomosis may conceal irregularities at the heel and toe sites and occlude in the further postoperative course [1].
A series of devices capable of fashioning venous-to-coronary anastomoses have been introduced to achieve this goal [2–8]. All of them exhibit benefits and limitations pertaining to handling, physical properties, and functional merit compared to the surgeons' manual dexterity. Ultimately, the decisive endpoint of utilizing such coupling devices is graft patency in the long term, which can be best assessed by angiography or MRI [9–14]. However, in most of the cases, angiographic outcome of the automatically tailored anastomoses has not been evaluated systematically and has not been presented other than in brief communications. Heterogenic reports derived from anecdotal case presentations render carefully designed studies inexorable for the further evolution of these novel techniques.
Converge Medical (Sunnyvale, CA) has developed a proprietary system to produce a rapid, precise sutureless anastomosis. The device relies on a series of concentric mating anastomotic frames which tie the anastomotic halves together by clamping them. Fig. 1A shows a schematic intraoperative view of the mating system for the generation of the anastomosis. The Converge Medical, Inc. Sutureless anastomotic system produces a unique lumen geometry with high precision and eliminates suture constriction or other irregularities which are not unusual following hand-fashioned anastomosis. Because of its design, the Coverge SAS results in a consistent flow-line pattern which cannot be reproduced consistently with standard suturing techniques. Sutures create discrete points of stress in tissue and can be the prime determinate of anastomotic biomechanics. A more homogenous distribution of anastomotic stress can be achieved by the Converge clamping-coupler. By fixing the frames in place, anastomotic healing can occur. In the present angiographic study we examine the 2-year patency of suturelessly produced anastomoses and discuss the capacity of the Converge-system to eliminate the need for manually sutured anastomoses.
2. Patients and methods
Thirty-three patients with advanced coronary artery disease enrolled in a two-center, non-randomized study and underwent sutureless anastomotic coupling with the Converge device. The enrollment and patient informed consent were realized in compliance with our institution's Ethics Committee regulations and following approval. At the time of presentation for follow-up coronary angiography, history for postoperative symptomatology was obtained, including chest pain, shortness of breath, physical load until symptoms begin, and bleeding from various sources. The sutureless anastomoses were only venoarterial. The device is not yet refined to perform a delicate arterioarterial anastomosis. Exclusion criteria were severely sclerotic and calcified coronaries, tandem stenoses, too small or fragile-appearing vessels, or vessels with an inadequate flow distribution area. Also, intramuscular segments were excluded as a potential anastomotic target. Patients with multiple-stented target coronaries were also excluded. Patients with multiple-stented target coronaries were also excluded. From these patients a total of 15 consented to angiographic monitoring and underwent follow-up catheterization for the evaluation of patency of the coupled grafts, between 19 and 27 months after operation.
Patient mean age was 65.9±8.6 years at follow up. Thirteen male and two female patients underwent long term angiography. Mean left ventricular ejection fraction (EF) was 60.6±10.3%. Preoperative myocardial infarction was known in 38.4% of the subjects involved. None of the patients suffered of heart failure at the time of operation. As many as 77% of the patients had hyperlipidemia, 69.2% had hypertension and 15.4% had diabetes. The mean follow-up time was 1.8±0.4 years (Table 1).
The coupler system consists of a set of concentric mating anastomotic frames that clamp vessel ends together to promote anastomotic healing. The basic mechanism of the Converge device utilizes two nickel-titanium alloy (Nitinol) frames which capture and stabilize the vein and coronary vessel margins in a predefined position (Fig. 1B), [www.convergemed.com/technology.html]. Every CABG procedure involved one singular sutureless Converge anastomosis. The mean size of the target vessel destined for sutureless anastomosis was 3–4 mm in 69%, and between 2–2.5 mm in 31% of the cases. The first diagonal branch of the left coronary artery was the target in 6 of 15 cases. The right coronary artery was anastomosed in 5 of 15 patients, the circumflex artery in 1 of 15 patients and obtuse marginal branches in 3 of 15 patients. The cumulative number of anastomoses (including the hand-sewn ones) per patient was 3.7±0.6. Blood flow over the mechanical anastomosis was measured after Converge coupling using a transit time method with a 3-mm ultrasonic flow probe (HT-313 Flow meter, Transonic Systems Inc). Coupled anastomosis flow ranged from 23 to 92 ml/min and averaged at 57.8±10.2 ml/min. Duration of operation was 218±27.6 min. Mean cross clamp time was 39.4±9.2 min. Loading time of the coupler was 435±105 s. The anastomotic time for the sutureless anastomosis using the Converge system was 118.3±48.9 s. The cumulative postoperative blood loss was 680.8±270.4 ml. The maximal values for serum Creatine Kinase (CK) was 784±186 IU/ml, those for the isoenzyme CK-MB averaged at 26.4±9.1 IU/ml (Table 2). In 58% of the cases the anastomotic coupling was carried out without any difficulty. In 16% of the cases coupled anastomosis was laborious, in particular with problematic visualization of the heel or toe of the anastomosis following its accomplishment. Three of the anastomoses required modification, two with a suture and one with glue.
3. Results
Postoperative follow-up coronary angiographies were uneventful and successful in identifying the coupled vein-to-graft anastomosis (Fig. 2). In the hand-sewn anastomoses the angiographic morphology was as follows: in one patient, a sequential vein graft supplying a marginal branch of the left coronary artery and the RIVP was occluded. In another patient, a hand-sewn LIMA-on-LAD anastomosis was significantly obstructed (75%). No postoperative infarction or severe angina was reported by these patients. The coupled anastomosis was patent in both patients.
One single Converge-fashioned anastomosis to an obtuse marginal branch of the circumflex artery was occluded. There was no correlation of this finding to postoperative enzyme elevation or postoperative symptomatology. In addition, the occurrence of the occlusion did not correlate with low anastomotic flow, as measured intraoperatively, in this patient. All other grafts (14/15 captured with angiographic follow-up) were patent. The patient who required additional hand-made sutures for hemostasis did not exhibit unfavorable anastomotic morphology. Also, anastomotic and loading times did not correlate with angiographic outcome. Of the 38 cumulative hand-sewn venous graft anastomoses, four exhibited occlusion (10.5%).
4. Discussion
The low incidence of anastomotic occlusion underlines the efficacy and consistency of the anastomoses carried out using the Converge coupler. The lack of adverse effects associated with the use of the Converge anastomotic coupler renders this novel method safe and efficient for coronary revascularization.
Of note, the target coronary arteries which were subjected to the Converge coupling device, had a larger average diameter compared to the hand-sewn ones and were selected intraoperatively. A minimum of 2 mm in diameter is suitable for the automated coupling device. Therefore, a direct comparison between conventional and coupled anastomoses is not feasible at this point. However, a 93% patency at 2 years constitutes a consistent anastomotic performance compared to reported patency rates between 91% [11] and 95% [12] at 3 months, 88.3% at 1 year [13], and 95% at 5 years [14] for vein grafts, respectively. We must state that with approximately 50% of the patients dropping out, this percentage represents a fraction of the maximally obtainable results. The longevity of an initially patent anastomosis presupposes delicate handling of the approximated tissues, protection of the endothelium, optimal alignment for luminal tissue contact, precise suture lines, appropriate placement of the distal anastomoses to achieve adequate flow conditions and minimization of surgical trauma. These precautionary techniques are decisive for the success of a CABG procedure but are largely dependent on individual parameters. By circumventing manual parameters, such as tremor and experience by using the coupler, a symmetric and homogenous adaptation can be achieved. Furthermore, the 30° end-to-side anastomosis angle achieved by the Converge coupler may prevent exaggerated shear stress at the site of anastomosis and facilitate smooth inflow with minimal flow turbulence. Nevertheless, anastomotic obstruction and thrombosis [15] cannot be excluded, due to rheological factors or strut misalignment and device dysfunction. The latter was not observed in our patient group, as far as anastomotic leakage is concerned.
A potential disadvantage of the device might be the clip mechanism which fixes the anastomotic ends in place which may cause endothelial trauma in the case of extensive manipulation and relocation attempts. Furthermore, the intramural stress within the coupled walls of the saphenous grafts, as well as the coronary artery, could eventually be excessive and inhibit healing processes. The optimal range of anastomotic strength which guarantees persistence of the anastomotic stability cannot be derived from angiographic examinations. In some, strongly magnified angiographic figures of the Converge-anastomosis to the right coronary artery, a vertical view of the coupler shape and alignment to the anastomosed vessels can be obtained. The device's shape appears distorted and obliquely projected on vein-to-left coronary grafts, so that neither morphological information about the quality of the anastomotic lumen can be safely obtained, nor can prognostic statements be made. Part of the challenge is the fact that the Coupler has an internal frame and an external frame which create an image artifact. Getting a flow path image is challenging and difficult, but since these devices are novel, an appropriate protocol for examining their performance with angiography has not been developed yet.
The mere presence of a metal frame or its geometry in the bloodstream may give rise to degenerative changes in the intima. More profound experience as to the progression stages of obstruction in the lumen of the sutureless anastomosis, eventually through intravascular ultrasound techniques, may provide impetus for corrective modifications. Cost-effectiveness is a further prominent issue pertaining to the use of the entire array of anastomotic devices at the present time and constitutes a decisive factor for the recruitment of larger patient populations. The latter aspect is of utmost importance for the better definition of the surgical application of the Converge (and also other anastomotic devices) coupler and the expansion of the spectrum of indications to smaller vessels or port access, and endoscopic cardiac surgery approaches. Of note, we have used veins only for the Converge anastomoses. The system has to prove itself for arterial anastomoses as well, in order to maintain the option of utilization in patients who are scheduled for total arterial revascularization. Furthermore, more accurate morphological or functional results may have been obtained with the use of angio-CT or cine-MRT, both eligible for scanning Nitinol stents. Even though a single-plane angiographic image may not be entirely conclusive, images from multiple orientations would solve the problem.
4.1. Limitations of the study
We are surprised by the reluctance of some patients to make themselves available and cannot explain the dropouts, other than the unnecessary appearing additional catheterization. Those who were co-operative underwent a short, basic angiography for morphological evaluation, and no core-lab or TIMI conditions were applied.
In summary, the Converge anastomotic device is a reliable tool for the accomplishment of consistently patent anastomoses, as evaluated by mid-term angiography. Multicenter, randomized studies are expected to expedite the process of eventual improvements and provide comparative conclusions over the traditional, manual anastomotic practice.
References
Klima U, Falk V, Maringka M, Bargenda S, Badack S, Moritz A, Mohr F, Haverich A, Wimmer-Greinecker G. Magnetic vascular coupling for distal anastomosis in coronary artery bypass grafting: a multicenter trial. J Thorac Cardiovasc Surg 2003;126:1568–1574.
Eckstein FS, Bonilla LF, Englberger L, Eberli F, Windecker S, Berg TA, Romanens M, Immer FF, Carrel TP. First clinical results with a new mechanical connector for distal coronary artery anastomoses in CABG. Circulation 2002;106:I-1–I-4.
Niinami H, Takeuchi Y, Ichikawa S, Ban T, Higashita R, Suda Y, Suzuki S. Coronary artery bypass-grafting using interrupted anastomosis with the U-clip. Kyobu Geka 2001;54:1003–1006.
Tozzi P, Stumpe F, Ruchat P, Marty B, Corno AF, von Segesser LK. Preliminary clinical experience with the Heartflo anastomosis device. Thorac Cardiovasc Surg 2001;49:279–82.
Gundry SR, Black K, Izutani H. Sutureless coronary artery bypass with biologic glued anastomoses: preliminary in vivo and in vitro results. J Thorac Cardiovasc Surg 2000;120:473–477.
Carrel T, Englberger L, Keller D, Windecker S, Meier B, Eckstein F. Clinical and angiographic results after mechanical connection for distal anastomosis in coronary surgery. J Thorac Cardiovasc Surg 2004;127:1632–1634.
Calafiore AM, Bar-El Y, Vitolla G, Di Giammarco G, Teodori G, Iaco AL, Dalessandro SD, Di Mauro M. Early clinical experience with a new suture-less anastomtic device for proximal anastomosis of the saphenous vein to the aorta. J Thorac Cardiovasc Surg 2001;121:854–858.
Eckstein FS, Bonilla LF, Englberger L, Immer FF, Berg TA, Schmidli J, Carrel TP. The St Jude Medical symmetry aortic connector system for proximal vein graft anastomoses in coronary artery bypass grafting. J Thorac Cardiovasc Surg 2002;123:777–782.
Carrel TP, Eckstein FS, Englberger L, Berdat PA, Schmidli J. Clinical experiences with devices for facilitated anastomoses in coronary artey bypass surgery. Ann Thorac Surg 2004;77:1110–1120.
Riess FC, Helmold H, Hilfer I, Bader R, Stripling J, Loewer C, Wesner F, Bleese N. Clinical experience with the cor link device for proximal anastomosis of the saphenous vein to the aorta: a clinical, prospective, and randomized study. Heart Surg Forum 2002;5:345–353.
Lingaas PS, Hol PK, Lundblad R, Rein KA, Tonnesen TI, Svennevig JL, Hauge SN, Vatne K, Fosse E. Clinical and angiographic outcome of coronary surgery with and without cardiopulmonary bypass: a prospective randomized trial. Heart Surg Forum 2003;7:115–122.
Khan NE, De Souza A, Mister R, Flather M, Clague J, Davies S, Collins P, Wang D, Sigwart U, Pepper J. A randomized comparison of off-pump and on-pump multivessel coronary-artery bypass surgery. N Engl J Med 2004;350:21–28.
Kim KB, Lim C, Chae IH, Oh BH, Lee MM, Park YB. Off-pump coronary artery bypass may decrease the patency of saphenous vein grafts. Ann Thorac Surg 2001;72:S1033–S1037.
Tatoulis J, Buxton BF, Fuller JA. Patencies of 2127 arterial to coronary conduits over 15 years. Ann Thorac Surg 2004;77:93–101.
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