A novel secure transfixing blood vessel occluder: comparison with the hemoclip in the porcine model

Comparison of the incidence of intra-operative haemorrhage from ovarian vessels during ovariectomy and ovariohysterectomy of dogs and cats performed by inexperienced surgeons using surgeon's and constrictor knots

Aims: To compare the incidence of intra-operative haemorrhage from ovarian vessels during ovariectomy (OV) and ovariohysterectomy (OVH) in dogs and cats performed by inexperienced surgeons using surgeon's and constrictor knots to ligate the ovarian pedicles.Methods: All client-owned female dogs (n = 51) and cats (n = 102) that presented for OV or OVH at two referral clinics in Belgium and France from January to June 2019 were included. Surgeries were performed by inexperienced surgeons under the supervision of diplomates or residents of the European College of Veterinary Surgeons. During routine and emergency OV or OVH one pedicle of each animal was ligated using a constrictor knot and the other with a surgeon's knot, the side assigned randomly. Time taken to perform each knot and the number of ligatures that resulted in intraoperative haemorrhage from the ovarian vessels were recorded. Body condition score (BCS) was recorded for 33 dogs and 22 cats.Results: The median time taken to perform constrictor knots in dogs (81 seconds), was longer than for surgeon's knots (69 seconds; p = 0.005). In cats, the median time taken to perform constrictor knots (109 seconds) was also longer than for surgeon's knots (90.5 seconds; p = 0.02).The number of dogs that had intra-operative haemorrhages from pedicles ligated with constrictor knots (2/102; 3.9%) was less than those ligated with surgeon's knots (10/102; 19.6%; p = 0.027). The median BCS of dogs that experienced haemorrhage (n = 8; median 5/9, min 3/9, max 7/9) was higher (p = 0.019) than that of dogs that did not experience haemorrhage (n = 25; median 4/9, min 3/9, max 8/9).There was no evidence (p = 1.0) of a difference in the proportion of cats that experienced intra-operative haemorrhage from pedicles ligated with constrictor knots (3/44; 6.8%) and those ligated with surgeon's knots (2/44; 4.5%). Two-thirds of the haemorrhages with constrictor knots were caused by pedicle rupture during tightening.Conclusions: The rate of intraoperative haemorrhage from the ovarian pedicle was lower when a constrictor knot was used compared to a surgeon's knot in dogs but not in cats. While the constrictor knot was more time consuming to tie this is not likely to have a clinical impact. Use of this knot by inexperienced surgeons in dogs may help to reduce the risk of intraoperative haemorrhage during OVH/OV.

A preclinical animal study of a novel, simple, and secure duct and vessel occluder for laparoscopic surgery

BACKGROUND

Secure occlusion of large blood vessels and ductal structures is critical to all surgeries and remains a challenge in many minimally invasive procedures. This study compares in vivo use of the Amsel Occluder (AO) for secure laparoscopic blood vessel and duct closure, with one of the many commercially available hemoclips (Ligaclip®), in the porcine model.

METHODS

Laparoscopic closure of vessels and ducts was performed on 12 swine to compare the ease of use, safety and efficacy of the AO with a hemoclip, as well as the tissue response at > 30 days (10 swine). All vessels and ducts were occluded and then transected between the occluding clips. Any bleeding or leakage was noted. In the chronic study, confirmation of satisfactory vessel occlusion post nephrectomy was determined by laparotomy as well as by contrast angiography and venography. The tissue response and healing was evaluated by a histopathological study for the effects of any biological incompatibilities.

RESULTS

In the acute laparoscopic study, a total of 24 occlusions between 2 and 10 mm were performed with the AO (n = 19) and hemoclip (n = 5). In the chronic study, 5 nephrectomies (AO n = 3, hemoclip N = 2) and 5 cholecystectomies (AO n = 3, hemoclip n = 2) were performed with survival ranging from 42 to 72 days. One pig who sustained a splenic injury at trocar insertion and suffered a delayed ruptured spleen with massive hemorrhage on postoperative day 22. Unlike occlusion with the AO, multiple hemoclips were used for each vessel occlusion. Histopathological examination showed no difference in the tissue response and healing of the AO and hemoclip.

CONCLUSIONS

The Amsel Vessel occluder delivered laparoscopically provides an occlusion similar to a hand-sewn transfixion suture, is simple to use, and creates an occlusion which is not only more secure, but also as safe with respect to the health of the surrounding tissues, as that of the widely used hemoclip (Ligaclip®).

A preclinical animal study of a novel, simple, and secure percutaneous vessel occluder for the treatment of varicose veins

BACKGROUND

Secure, permanent occlusion of the great and small saphenous veins, their tributaries, and perforators is critical for the successful treatment of varicose veins. Current minimally invasive methods replacing surgery are all endoluminal and involve heat (radiofrequency or laser), chemicals (sclerosants and glues), or a combination of mechanical and chemical interventions. This study evaluated in a porcine model the performance of a percutaneous delivery of the Amsel Vessel Occluder (AVO; Amsel Medical Corp, Cambridge, Mass) using ultrasound guidance. The AVO has received United States Food and Drug Administration premarket 510(k) clearance for use in open surgical procedures for tubular structures with diameters of 2 to 7 mm.

METHODS

The AVO, a novel mechanical occlusion clip similar to a transfixion suture, is delivered through an 18-gauge hypodermic needle. The AVO is subsequently expanded on either side of the vessel wall, collapsed, and locked together to effect secure vascular occlusion, thus transfixing the targeted vessel. The targeted vessels in five swine (weight >60 kg) under general anesthesia were identified, and the vessel size was measured. Patency of the targeted vessels was confirmed on duplex ultrasound imaging. Each animal provided multiple vessels for percutaneous AVO occlusion. Occlusion was confirmed by duplex ultrasound imaging and by direct examination of the occluded vessel after open surgical exploration.

RESULTS

Thirty vessel occlusions were performed percutaneously, including the common and superficial femoral arteries and veins (n = 24), the carotid artery (n = 4), and the external jugular vein (n = 1) and external jugular vein tributary (n = 1). Measured vessel sizes ranged from 1.8 to 12.7 mm. After vessel transfixion, occlusion was achieved in <30 seconds. A second AVO, if necessary, was delivered to completely occlude the targeted vessel where the vessel was >7 mm diameter (n = 2; external jugular vein, 12.7 mm; carotid artery, 7 mm), or where the initial AVO did not occlude the vessel because of nontransfixion (n = 1). Surgical exposure after occlusion confirmed that all targeted vessels were successfully occluded and demonstrated no evidence of injury to any of the adjacent structures.

CONCLUSIONS

This study confirms that the AVO can be effectively delivered percutaneously under ultrasound guidance to occlude blood vessels in the porcine model and may be a useful, time-saving, and cost-effective adjunct to current primary methods of treating reflux in the saphenous veins, their tributaries, or perforators for the treatment of symptomatic varicose veins.