AN EXPERIMENTAL STUDY OF MICROVASCULAR PATENCY USING A CONTINUOUS SUTURE TECHNIQUE By R. B. HAMILTON,F.R.A.C.S. F.R.C.S.,
B. McC. O’BRIEN, B.Sc., M.D.,M.S.,
and F.R.A.C.S.,
F.A.C.S.
Microsurgery Research Unit, St Vincent’s Hospital, Melbourne, Australia THE ability to anastomose successfully and reliably small vessels of I mm diameter has been established experimentally and clinically. Experimentally a follow-up patency rate of 98 per cent has been achieved in arteries and g2 per cent in veins using an interrupted suture technique (Hayhurst et al., 1974). Chase and Schwartz (1962) reported better results with simple interrupted sutures than with a continuous suture. This early study was performed with techniques, instruments and sutures less refined than available today. No reports in the recent literature on continuous microvascular suturing have been published and it was decided to reinvestigate this technique. MATERIAL AND METHODS
Anastomoses were carried out on New Zealand white rabbits anaesthetised with Nembutal intravenously and maintained on oxygen, nitrous oxide and halo&me by mask. End-to-end anastomoses were done on the femoral artery and vein, approximately I mm in diameter. A single stay IO/O nylon on a BV2 needle (Ethicon) was used for the anastomoses. suture was inserted on one side of the vessel. Then, commencing at 180” from the stay suture, a continuous suture was inserted moving circumferentially around the vessel and tied to itself at the point of commencement (Fig. I). No topical anticoagulants or antispasmodic agents were used.
FIG. I. A. FIG. I. B.
Completed
A continuous anastomosis
suture in progress with two guide sutures.
of the same vessel.
Address for reprints: B. McC. O’Brien, Melbourne, Victoria 3065, Australia.
Director, IS3
Note the dilatation
Microsurgery
Research
at the site of repair.
Unit, St Vincent’s
Hospital,
154
BRITISH JOURNAL OF PLASTIC SURGERY
Twenty-seven arterial anastomoses and 25 venous anastomoses were performed using this method. Patency was tested from 5 to 14 days, average 7.5 days. One rabbit was re-explored at 3 weeks and another at 6 months. RESULTS
Twenty-five of the 27 arterial anastomoses were found to be patent. This represents a patency of 92.5 per cent (Table). Twenty-one of the 25 venous anastomoses were patent at exploration. This represents a patency of 84 per cent (Table). Two arteries and 2 veins re-explored at 3 weeks were still patent, as was the I artery and I vein re-explored at 6 months. The failures, 2 arteries and 4 veins, were thought to be due to technical errors. TABLE
Patency in vessels-continuous
Arteries Veins
suture
Number of vessels anastomosed
Number patent (Av. 7.5 days)
27 25
2.5
21
O/ePatency 92.6 84.0
DISCUSSION
The continuous suture technique is more rapid than an interrupted suture method but is not without its problems. Difficulties were constantly experienced with the suture becoming tangled in instruments, particularly the clamp. Great care was needed because if the suture material ruptured leaving only a short thread, the anastomosis was abandoned and repeated after excision of the vessel edges. If a long thread remained after breakage, the suture could be tied to a fresh suture and the continuous suture recommenced from that site. Bleeding from the anastomosis after release of the clamps was not a significant problem. Occasionally an additional suture had to be inserted to secure haemostasis. In the arterial anastomosis, vessel narrowing was not encountered. On the contrary, when the clamps were released the vessel dilated and at the anastomotic site the vessel diameter was slightly larger.
Continuous suture technique gives acceptable patency rates in the anastomosis of small arteries and veins, comparable to those obtained with interrupted sutures. Whilst it has the advantage of time saving, the problems associated with entrapment of the suture material in the vessel clamp and breakage of the suture, requiring repetition of the anastomosis, make it a less favourable method for use in the clinical situation where the operating conditions are not as ideal as in the laboratory. This project is supported by a grant from the National Health and Medical Research Council of Australia. REFERENCES CHASE,M. D. and SCHWARTZ, S. L. (1962). Consistent patency of 1-5 mm arterial anastomoses. Surgical Forum, 13, 220. HAYHURST? J. W. and O’BRIEN,B. McC. (1975). An experimental study of microvascular tecbmque, patency rates and related factors. British Journal of Surgery, 28, 128.
B. McC. O’BRIEN, B.Sc., M.D.,M.S.,
and F.R.A.C.S.,
F.A.C.S.
Microsurgery Research Unit, St Vincent’s Hospital, Melbourne, Australia THE ability to anastomose successfully and reliably small vessels of I mm diameter has been established experimentally and clinically. Experimentally a follow-up patency rate of 98 per cent has been achieved in arteries and g2 per cent in veins using an interrupted suture technique (Hayhurst et al., 1974). Chase and Schwartz (1962) reported better results with simple interrupted sutures than with a continuous suture. This early study was performed with techniques, instruments and sutures less refined than available today. No reports in the recent literature on continuous microvascular suturing have been published and it was decided to reinvestigate this technique. MATERIAL AND METHODS
Anastomoses were carried out on New Zealand white rabbits anaesthetised with Nembutal intravenously and maintained on oxygen, nitrous oxide and halo&me by mask. End-to-end anastomoses were done on the femoral artery and vein, approximately I mm in diameter. A single stay IO/O nylon on a BV2 needle (Ethicon) was used for the anastomoses. suture was inserted on one side of the vessel. Then, commencing at 180” from the stay suture, a continuous suture was inserted moving circumferentially around the vessel and tied to itself at the point of commencement (Fig. I). No topical anticoagulants or antispasmodic agents were used.
FIG. I. A. FIG. I. B.
Completed
A continuous anastomosis
suture in progress with two guide sutures.
of the same vessel.
Address for reprints: B. McC. O’Brien, Melbourne, Victoria 3065, Australia.
Director, IS3
Note the dilatation
Microsurgery
Research
at the site of repair.
Unit, St Vincent’s
Hospital,
154
BRITISH JOURNAL OF PLASTIC SURGERY
Twenty-seven arterial anastomoses and 25 venous anastomoses were performed using this method. Patency was tested from 5 to 14 days, average 7.5 days. One rabbit was re-explored at 3 weeks and another at 6 months. RESULTS
Twenty-five of the 27 arterial anastomoses were found to be patent. This represents a patency of 92.5 per cent (Table). Twenty-one of the 25 venous anastomoses were patent at exploration. This represents a patency of 84 per cent (Table). Two arteries and 2 veins re-explored at 3 weeks were still patent, as was the I artery and I vein re-explored at 6 months. The failures, 2 arteries and 4 veins, were thought to be due to technical errors. TABLE
Patency in vessels-continuous
Arteries Veins
suture
Number of vessels anastomosed
Number patent (Av. 7.5 days)
27 25
2.5
21
O/ePatency 92.6 84.0
DISCUSSION
The continuous suture technique is more rapid than an interrupted suture method but is not without its problems. Difficulties were constantly experienced with the suture becoming tangled in instruments, particularly the clamp. Great care was needed because if the suture material ruptured leaving only a short thread, the anastomosis was abandoned and repeated after excision of the vessel edges. If a long thread remained after breakage, the suture could be tied to a fresh suture and the continuous suture recommenced from that site. Bleeding from the anastomosis after release of the clamps was not a significant problem. Occasionally an additional suture had to be inserted to secure haemostasis. In the arterial anastomosis, vessel narrowing was not encountered. On the contrary, when the clamps were released the vessel dilated and at the anastomotic site the vessel diameter was slightly larger.
Continuous suture technique gives acceptable patency rates in the anastomosis of small arteries and veins, comparable to those obtained with interrupted sutures. Whilst it has the advantage of time saving, the problems associated with entrapment of the suture material in the vessel clamp and breakage of the suture, requiring repetition of the anastomosis, make it a less favourable method for use in the clinical situation where the operating conditions are not as ideal as in the laboratory. This project is supported by a grant from the National Health and Medical Research Council of Australia. REFERENCES CHASE,M. D. and SCHWARTZ, S. L. (1962). Consistent patency of 1-5 mm arterial anastomoses. Surgical Forum, 13, 220. HAYHURST? J. W. and O’BRIEN,B. McC. (1975). An experimental study of microvascular tecbmque, patency rates and related factors. British Journal of Surgery, 28, 128.
