The Vascular Join: a new sutureless anastomotic device to perform end-to-end anastomosis. Preliminary results in an animal model
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《血管的通路杂志》
Department of Cardiovascular Surgery, Centre Hpitalier Universitaire Vaudois (CHUV), 46, rue du Bugnon, CH-1011 Lausanne, Switzerland
Presented at the 55th International Congress of the European Society for Cardiovascular Surgery, St Petersburg, Russian Federation, May 11–14, 2006.
Abstract
Standard vascular techniques don't meet new surgeons' needs for the more complex vascular reconstructions, minimal invasive approaches and robotic surgery. Therefore, alternative ways to perform vascular anastomosis are always welcome. We present a new sutureless vascular connector and the first animal study. The Vascular Join consists of two metallic rings fixed to the extremity of two conduits being joined together, connected with a snap-on system. The key element that makes this device different from all other sutureless devices is that there is no foreign material inside the vessel lumen. In 10 adult sheep, both carotid arteries were prepared and severed after heparinisation. Twenty end-to-end vascular anastomoses were performed and controlled with intravascular ultrasound and colour-Doppler. Animals were sacrificed and a histopathological analysis was carried out. All anastomoses were successfully completed without bleedings, stenosis or occlusions. The histological results confirmed the perfect vessel edges apposition and absence of foreign material in the vessel lumen. The intimal layer was intact. Vascular Join can easily perform sutureless end-to-end anastomoses and it can be used either with biological or prosthetic materials. Further animal studies are underway to assess the long-term results. Following the same technical criteria, we are developing an end-to-side anastomotic device.
Key Words: Vascular connector; Sutureless anastomosis; Suture technique
1. Introduction
The standard surgical technique to perform end-to-end vascular anastomosis is a hand-held suture based on the principles of the technique described by Alexis Carrel in 1902 [1]. Despite the fact that about 60 different anastomotic techniques have been already proposed over the last 100 years, we still use Carrel's technique because it is reliable and provides, up to now, the best long-term results. To be worldwide accepted, any new medical device or surgical technique should be reliable and should have as excellent long-term results as the Carrel technique.
During the last years the surgical environment has become more and more challenging for the cardiovascular surgeon. The introduction of minimally invasive approaches, for example, has demonstrated that there are technical problems to perform a standard vascular anastomosis through small incisions. Despite new technologies that have been developed for this purpose (robotic surgery systems) some problems are still unsolved [2,3]. Moreover, the ageing of the population coupled with the patients' comorbidities increase, are increasing the surgical difficulties and today's vascular surgeons have to deal with very complex vascular reconstructions.
Therefore, in order to reduce the technical demand and improve the quality of the surgical procedure, new alternative ways to construct vascular anastomosis are always welcome. During the past ten years, several sutureless connectors have been brought to the attention of cardiovascular surgeons, but most of them have been withdrawn from the market because of the poor mid- and long-term results [4,5].
The new vascular connector (Vascular Join, Idee & Sviluppo Srl, Bologna, Italy) represents a new anastomotic technology for end-to-end anastomosis that can reduce the impact of surgical dexterity on anastomosis outcomes and seems to fulfil the needs of today's surgeon.
In this article we present the Vascular Join and we report the first clinical experience in an animal model.
2. Materials and methods
The new Vascular Join has been designed to easily perform end-to-end vascular anastomosis. As you can see in Fig. 1, it consists of two metallic rings fixed to the extremity of the two conduits (either biological or synthetic materials) being joined together. The metallic rings (similar to a stainless steel crown) are surrounded by two polymeric rings which can be connected together with a snap-on system. This system can guarantee the continuity of the severed conduit and, more important, can guarantee a layer-by-layer vascular connection. Using the new vascular connector, indeed, the vessel edges are joined together layer by layer (edge-to-edge repair) and no foreign material is in contact with the intima or with blood. Since the rings stay outside the vessel, the connection between the rings and the vessel is made by pins (from 6 to 18 depending on the vessel diameter) that penetrate within the vessel without passing through it: in this way the metallic pins are not in contact with the endothelium and will never damage it.
Different Vascular Join sizes ranging from 3 mm to 12 mm of diameter are available at the moment. To connect the connector to the vessel, a free vascular edge of 1 cm is needed and a holder has been developed to facilitate this procedure. First of all the metallic and the polymeric rings are positioned around the vessel. Then, the smooth holder's tip is inserted into the vessel lumen to keep it widely open and in contact with the ring. To move the metallic tips within the vascular wall, the holder has a mechanism that pushes the metallic ring into the polymeric ring for 2 mm. During this movement, the polymeric ring and the vessel remain still whereas the tips enter within the vessel wall (Fig. 2).
2.1. Experimental set-up
Ten adult sheep (45–55 kg) received general anaesthesia and were monitored by electrocardiogram (ECG) and oxygen blood saturation measurement. The femoral artery was isolated and a catheter for systemic arterial blood pressure monitoring was inserted. Both carotid arteries were isolated and the flow measured using a colour-Doppler. Once the heparin has been injected (100 U/kg, to keep the activating clotting time above 200 s), the carotid arteries were clamped, severed and anatomosed in end-to-end fashion using the new Vascular Join. After the procedure, the carotid blood flow was measured again distal to the anastomosis, using the colour-Doppler probe. In ten cases the intravascular ultrasound (IVUS with Sonicath UltraTM 3.2, 20 MHz-Imaging Catheter, Medi.tech Boston Scientific Corporation) was used to measure the anastomotic diameters in systole and diastole 1 mm proximal and distal to the anastomotic device. After two hours the animals were sacrificed and a histopathological analysis was carried out to evaluate the quality of the anastomosis.
All animals received humane care in compliance with the European Convention on Animal Care and our institutional Ethics Committee approved the study.
2.2. Aim of the study
This first Vascular Join clinical study in an animal model was designed to:
Evaluate the consistency and the reproducibility of the sutureless vascular anastomosis made with the Vascular Join;
Evaluate the restoring of the vessel continuity;
Confirm the absence of bleeding;
Analyse the presence/absence of flow turbulences into the connector (colour-Doppler);
Verify the s‘layer by layer’ vessel apposition;
Confirm the absence of foreign material into the vessel lumen.
3. Results
Twenty carotid anastomoses were performed using the new vascular connector (Fig. 3a). The mean carotid artery diameter was 5±0.5-mm. During the procedure the mean blood pressure was 80±12 mmHg. Twenty 5-mm sutureless vascular connectors were used and no technical failure was detected. The mean carotid blood flow was 312±53 ml/min before the anastomosis construction and 320±40 ml/min after the procedure. We did not observe any active bleeding coming from the sutureless anastomosis and the colour-Doppler coupled with the IVUS confirmed the good anastomotic results. The anastomoses were 100% patent and no intimal flaps or dissections were detected. The vascular Doppler confirmed also the presence of a laminar flow into the device and no blood turbulences were found (maximal flow velocity: 100 cm/s) (Fig. 3b). The histological work-up showed that the metallic pins were within the vessel wall and did not touch the intimal layer. Foreign material was not detected in the vessel lumen, confirming the perfect ‘edge-to-edge’ vessel apposition (Fig. 4). Signs of acute inflammatory response were not detected in any specimens.
4. Discussion
New technologies can potentially facilitate and help the cardiovascular surgeon during his daily practice. Benefits coming from brand new devices can help the vascular surgeon to execute more and more complex operations in patients with several comorbidities, using minimal invasive approaches. During the last years, indeed, more complex vascular reconstructions and technically demanding procedures in older patients have increased the surgical risk.
For several reasons, cardiovascular surgery can get big benefits from the new end-to-end and end-to-side (still in project) vascular connectors that have been developed in our hospital during the last few years. These devices can simplify and standardise the execution of vascular anastomosis and can reduce the impact of surgical dexterity on anastomosis outcomes.
In the reported acute animal study, the new end-to-end vascular connector has proven to be a reliable surgical instrument to perform consistent and reproducible vascular anastomosis. This surgical device is simple and intuitive. The deployment system is very easy to use, the anastomosis construction takes less than one minute and no major bleedings have been experienced. However, these characteristics are common to all anastomotic devices developed in the last 10 years [4–6], and can be considered as a standard requirement for any new anastomotic device.
The element that makes this new Vascular Join unique is the complete absence of foreign material (metal or polymers) into the vessel lumen and as a consequence there is no foreign material in contact with blood. Histological analyses confirmed that metallic pins stay within the vessel wall (in the media layer) and, in the majority of the specimens, do not even reach the lamina basalis. Pins have a diameter of 100 microns and their traumatic action on the vessel wall can be compared to that of a 7–0 needle. Absence of foreign material into the vessel lumen reduces flow disturbances and may reduce the disposition toward the development of intimal hyperplasia or thrombosis [7–11]. In our series the three layers of the arterial wall are faced ‘layer by layer’ so that intima is in contact with intima, media with media and adventitia with adventitia. This is the first time that a surgical technique for end-to-end sutureless vascular anastomosis provides such a natural and physiological vascular reconstruction. Another advantage coming from this anastomotic device is that it can be easily used either with biological and prosthetic material.
One potential drawback of this technique is the compliance of the anastomosis because rigid metallic components can modify the elastic properties of the vessel wall [8,10]. More studies are necessary to assess this potential problem.
We have identified some limitations in this preliminary study: (1) the chosen animal model had normal vessels and even if the connector works better with rigid conduits, the assumption that it is the ideal device for calcified vessels has to be confirmed by further clinical studies. (2) We have learned from the recent past that even the most attractive and promising sutureless devices have failed in long-term clinical results. Therefore, to become widely accepted, a sutureless device must fulfil three essential characteristics: easiness, precision and, above all, evidence of long-term effectiveness. New animal studies are underway to assess the long-term results of this attractive brand new anastomotic device.
Another major concern is that the majority of complex vascular reconstructions need end-to-side anastomosis and could benefit from an end-to-side anastomotic device developed following the same criteria used to create the Vascular Join. Despite the project and the construction of this end-to-side anastomotic device being more complex, many efforts have already been done and a prototype is ready to be tested in our laboratories.
Acknowledgements
We thank Mr. Enzo Borghi from Idee&Sviluppo Sarl, for its precious financial and technical support in this study.
References
Carrel A. La technique operatoire des anastomoses vasculaires et la transplantation des visceres. Lyon Med 1902; 98:859–863.
Mack MJ, Acuff TE, Casimir-Ahn H, Lnn UJ, Jansen EWL. Video-assisted coronary bypass grafting on the beating heart. Ann Thorac Surg 1997; 63:S100–103.
Falk V, Diegeler A, Walther T, Banush J, Brucerius J, Raumans J, Autschbach R, Mohr FW. Total endoscopic computer enhanced coronary artery bypass grafting. Eur J Cardiothorac Surg 2000; 17:38–45.
Tozzi P, Corno AF, von Segesser LK. Sutureless coronary anastomoses: revival of old concepts. Eur J Cardiothorac Surg Oct 2002; 22:565–570.
Carrel T, Eckstein F, Englberger L, Berdat P, Schmidli J. Clinical experience with devices for facilitated anastomoses in coronary artery bypass surgery. Ann Thorac Surg 2004; 77:1110–1120.
Tozzi P, Solem JO, Boumzebra D, Mucciolo A, Genton CY, Chaubert P, von Segesser LK. Is the Graft Connector a valid alternative to running suture in end-to-side coronary arteries anastomoses Ann Thorac Surg Sep 2001; 72:S999–1003.
Scheltes JS, van Andel CJ, Pistecky PV, Borst C. Coronary anastomotic devices: blood-exposed non-intimal surface and coronary wall stress. J Thorac Cardiovasc Surg 2003; 126:191–196.
Klein SR, Goldberg L, Miranda RM. Effect of suture technique on arterial anastomotic compliance. Arch Surg Jan 1982; 117:45–47.
Dobrin PB. Mechanical factors associated with the development of intimal hyperplasia with respect to vascular grafts. ed. Intimal hyperplasia 1994;In: Dobrin PB. Austin: RG Landes85–109. In.
Baungartner N, Dobrin PB, Morasch M, Dong Q-s, Mrkvicka R. Influence of suture technique and suture material selection on the mechanics of end-to-end and end-to-side anastomoses. J Thor Cardiovasc Surg 1996; 111:1063–1072.
Ballyk PD, Walsh C, Butany J, Ojha M. Compliance mismatch may promote graft-artery intimal hyperplasia by altering suture-line stresses. J Biomech 1998; 31:229–237.(Enrico Ferrari, Piergiorgio Tozzi and Lu)
Presented at the 55th International Congress of the European Society for Cardiovascular Surgery, St Petersburg, Russian Federation, May 11–14, 2006.
Abstract
Standard vascular techniques don't meet new surgeons' needs for the more complex vascular reconstructions, minimal invasive approaches and robotic surgery. Therefore, alternative ways to perform vascular anastomosis are always welcome. We present a new sutureless vascular connector and the first animal study. The Vascular Join consists of two metallic rings fixed to the extremity of two conduits being joined together, connected with a snap-on system. The key element that makes this device different from all other sutureless devices is that there is no foreign material inside the vessel lumen. In 10 adult sheep, both carotid arteries were prepared and severed after heparinisation. Twenty end-to-end vascular anastomoses were performed and controlled with intravascular ultrasound and colour-Doppler. Animals were sacrificed and a histopathological analysis was carried out. All anastomoses were successfully completed without bleedings, stenosis or occlusions. The histological results confirmed the perfect vessel edges apposition and absence of foreign material in the vessel lumen. The intimal layer was intact. Vascular Join can easily perform sutureless end-to-end anastomoses and it can be used either with biological or prosthetic materials. Further animal studies are underway to assess the long-term results. Following the same technical criteria, we are developing an end-to-side anastomotic device.
Key Words: Vascular connector; Sutureless anastomosis; Suture technique
1. Introduction
The standard surgical technique to perform end-to-end vascular anastomosis is a hand-held suture based on the principles of the technique described by Alexis Carrel in 1902 [1]. Despite the fact that about 60 different anastomotic techniques have been already proposed over the last 100 years, we still use Carrel's technique because it is reliable and provides, up to now, the best long-term results. To be worldwide accepted, any new medical device or surgical technique should be reliable and should have as excellent long-term results as the Carrel technique.
During the last years the surgical environment has become more and more challenging for the cardiovascular surgeon. The introduction of minimally invasive approaches, for example, has demonstrated that there are technical problems to perform a standard vascular anastomosis through small incisions. Despite new technologies that have been developed for this purpose (robotic surgery systems) some problems are still unsolved [2,3]. Moreover, the ageing of the population coupled with the patients' comorbidities increase, are increasing the surgical difficulties and today's vascular surgeons have to deal with very complex vascular reconstructions.
Therefore, in order to reduce the technical demand and improve the quality of the surgical procedure, new alternative ways to construct vascular anastomosis are always welcome. During the past ten years, several sutureless connectors have been brought to the attention of cardiovascular surgeons, but most of them have been withdrawn from the market because of the poor mid- and long-term results [4,5].
The new vascular connector (Vascular Join, Idee & Sviluppo Srl, Bologna, Italy) represents a new anastomotic technology for end-to-end anastomosis that can reduce the impact of surgical dexterity on anastomosis outcomes and seems to fulfil the needs of today's surgeon.
In this article we present the Vascular Join and we report the first clinical experience in an animal model.
2. Materials and methods
The new Vascular Join has been designed to easily perform end-to-end vascular anastomosis. As you can see in Fig. 1, it consists of two metallic rings fixed to the extremity of the two conduits (either biological or synthetic materials) being joined together. The metallic rings (similar to a stainless steel crown) are surrounded by two polymeric rings which can be connected together with a snap-on system. This system can guarantee the continuity of the severed conduit and, more important, can guarantee a layer-by-layer vascular connection. Using the new vascular connector, indeed, the vessel edges are joined together layer by layer (edge-to-edge repair) and no foreign material is in contact with the intima or with blood. Since the rings stay outside the vessel, the connection between the rings and the vessel is made by pins (from 6 to 18 depending on the vessel diameter) that penetrate within the vessel without passing through it: in this way the metallic pins are not in contact with the endothelium and will never damage it.
Different Vascular Join sizes ranging from 3 mm to 12 mm of diameter are available at the moment. To connect the connector to the vessel, a free vascular edge of 1 cm is needed and a holder has been developed to facilitate this procedure. First of all the metallic and the polymeric rings are positioned around the vessel. Then, the smooth holder's tip is inserted into the vessel lumen to keep it widely open and in contact with the ring. To move the metallic tips within the vascular wall, the holder has a mechanism that pushes the metallic ring into the polymeric ring for 2 mm. During this movement, the polymeric ring and the vessel remain still whereas the tips enter within the vessel wall (Fig. 2).
2.1. Experimental set-up
Ten adult sheep (45–55 kg) received general anaesthesia and were monitored by electrocardiogram (ECG) and oxygen blood saturation measurement. The femoral artery was isolated and a catheter for systemic arterial blood pressure monitoring was inserted. Both carotid arteries were isolated and the flow measured using a colour-Doppler. Once the heparin has been injected (100 U/kg, to keep the activating clotting time above 200 s), the carotid arteries were clamped, severed and anatomosed in end-to-end fashion using the new Vascular Join. After the procedure, the carotid blood flow was measured again distal to the anastomosis, using the colour-Doppler probe. In ten cases the intravascular ultrasound (IVUS with Sonicath UltraTM 3.2, 20 MHz-Imaging Catheter, Medi.tech Boston Scientific Corporation) was used to measure the anastomotic diameters in systole and diastole 1 mm proximal and distal to the anastomotic device. After two hours the animals were sacrificed and a histopathological analysis was carried out to evaluate the quality of the anastomosis.
All animals received humane care in compliance with the European Convention on Animal Care and our institutional Ethics Committee approved the study.
2.2. Aim of the study
This first Vascular Join clinical study in an animal model was designed to:
Evaluate the consistency and the reproducibility of the sutureless vascular anastomosis made with the Vascular Join;
Evaluate the restoring of the vessel continuity;
Confirm the absence of bleeding;
Analyse the presence/absence of flow turbulences into the connector (colour-Doppler);
Verify the s‘layer by layer’ vessel apposition;
Confirm the absence of foreign material into the vessel lumen.
3. Results
Twenty carotid anastomoses were performed using the new vascular connector (Fig. 3a). The mean carotid artery diameter was 5±0.5-mm. During the procedure the mean blood pressure was 80±12 mmHg. Twenty 5-mm sutureless vascular connectors were used and no technical failure was detected. The mean carotid blood flow was 312±53 ml/min before the anastomosis construction and 320±40 ml/min after the procedure. We did not observe any active bleeding coming from the sutureless anastomosis and the colour-Doppler coupled with the IVUS confirmed the good anastomotic results. The anastomoses were 100% patent and no intimal flaps or dissections were detected. The vascular Doppler confirmed also the presence of a laminar flow into the device and no blood turbulences were found (maximal flow velocity: 100 cm/s) (Fig. 3b). The histological work-up showed that the metallic pins were within the vessel wall and did not touch the intimal layer. Foreign material was not detected in the vessel lumen, confirming the perfect ‘edge-to-edge’ vessel apposition (Fig. 4). Signs of acute inflammatory response were not detected in any specimens.
4. Discussion
New technologies can potentially facilitate and help the cardiovascular surgeon during his daily practice. Benefits coming from brand new devices can help the vascular surgeon to execute more and more complex operations in patients with several comorbidities, using minimal invasive approaches. During the last years, indeed, more complex vascular reconstructions and technically demanding procedures in older patients have increased the surgical risk.
For several reasons, cardiovascular surgery can get big benefits from the new end-to-end and end-to-side (still in project) vascular connectors that have been developed in our hospital during the last few years. These devices can simplify and standardise the execution of vascular anastomosis and can reduce the impact of surgical dexterity on anastomosis outcomes.
In the reported acute animal study, the new end-to-end vascular connector has proven to be a reliable surgical instrument to perform consistent and reproducible vascular anastomosis. This surgical device is simple and intuitive. The deployment system is very easy to use, the anastomosis construction takes less than one minute and no major bleedings have been experienced. However, these characteristics are common to all anastomotic devices developed in the last 10 years [4–6], and can be considered as a standard requirement for any new anastomotic device.
The element that makes this new Vascular Join unique is the complete absence of foreign material (metal or polymers) into the vessel lumen and as a consequence there is no foreign material in contact with blood. Histological analyses confirmed that metallic pins stay within the vessel wall (in the media layer) and, in the majority of the specimens, do not even reach the lamina basalis. Pins have a diameter of 100 microns and their traumatic action on the vessel wall can be compared to that of a 7–0 needle. Absence of foreign material into the vessel lumen reduces flow disturbances and may reduce the disposition toward the development of intimal hyperplasia or thrombosis [7–11]. In our series the three layers of the arterial wall are faced ‘layer by layer’ so that intima is in contact with intima, media with media and adventitia with adventitia. This is the first time that a surgical technique for end-to-end sutureless vascular anastomosis provides such a natural and physiological vascular reconstruction. Another advantage coming from this anastomotic device is that it can be easily used either with biological and prosthetic material.
One potential drawback of this technique is the compliance of the anastomosis because rigid metallic components can modify the elastic properties of the vessel wall [8,10]. More studies are necessary to assess this potential problem.
We have identified some limitations in this preliminary study: (1) the chosen animal model had normal vessels and even if the connector works better with rigid conduits, the assumption that it is the ideal device for calcified vessels has to be confirmed by further clinical studies. (2) We have learned from the recent past that even the most attractive and promising sutureless devices have failed in long-term clinical results. Therefore, to become widely accepted, a sutureless device must fulfil three essential characteristics: easiness, precision and, above all, evidence of long-term effectiveness. New animal studies are underway to assess the long-term results of this attractive brand new anastomotic device.
Another major concern is that the majority of complex vascular reconstructions need end-to-side anastomosis and could benefit from an end-to-side anastomotic device developed following the same criteria used to create the Vascular Join. Despite the project and the construction of this end-to-side anastomotic device being more complex, many efforts have already been done and a prototype is ready to be tested in our laboratories.
Acknowledgements
We thank Mr. Enzo Borghi from Idee&Sviluppo Sarl, for its precious financial and technical support in this study.
References
Carrel A. La technique operatoire des anastomoses vasculaires et la transplantation des visceres. Lyon Med 1902; 98:859–863.
Mack MJ, Acuff TE, Casimir-Ahn H, Lnn UJ, Jansen EWL. Video-assisted coronary bypass grafting on the beating heart. Ann Thorac Surg 1997; 63:S100–103.
Falk V, Diegeler A, Walther T, Banush J, Brucerius J, Raumans J, Autschbach R, Mohr FW. Total endoscopic computer enhanced coronary artery bypass grafting. Eur J Cardiothorac Surg 2000; 17:38–45.
Tozzi P, Corno AF, von Segesser LK. Sutureless coronary anastomoses: revival of old concepts. Eur J Cardiothorac Surg Oct 2002; 22:565–570.
Carrel T, Eckstein F, Englberger L, Berdat P, Schmidli J. Clinical experience with devices for facilitated anastomoses in coronary artery bypass surgery. Ann Thorac Surg 2004; 77:1110–1120.
Tozzi P, Solem JO, Boumzebra D, Mucciolo A, Genton CY, Chaubert P, von Segesser LK. Is the Graft Connector a valid alternative to running suture in end-to-side coronary arteries anastomoses Ann Thorac Surg Sep 2001; 72:S999–1003.
Scheltes JS, van Andel CJ, Pistecky PV, Borst C. Coronary anastomotic devices: blood-exposed non-intimal surface and coronary wall stress. J Thorac Cardiovasc Surg 2003; 126:191–196.
Klein SR, Goldberg L, Miranda RM. Effect of suture technique on arterial anastomotic compliance. Arch Surg Jan 1982; 117:45–47.
Dobrin PB. Mechanical factors associated with the development of intimal hyperplasia with respect to vascular grafts. ed. Intimal hyperplasia 1994;In: Dobrin PB. Austin: RG Landes85–109. In.
Baungartner N, Dobrin PB, Morasch M, Dong Q-s, Mrkvicka R. Influence of suture technique and suture material selection on the mechanics of end-to-end and end-to-side anastomoses. J Thor Cardiovasc Surg 1996; 111:1063–1072.
Ballyk PD, Walsh C, Butany J, Ojha M. Compliance mismatch may promote graft-artery intimal hyperplasia by altering suture-line stresses. J Biomech 1998; 31:229–237.(Enrico Ferrari, Piergiorgio Tozzi and Lu)