Reduced vascular trauma after temporary occlusion with modified Biemer and Yasargil clips

Characterizing the Impact of Compression Duration and Deformation-Related Loss of Closure Force on Clip-Induced Spinal Cord Injury in Rats

The clip-induced spinal cord injury (SCI) rat model is pivotal in preclinical SCI research. However, the literature exhibits variability in compression duration and limited attention to clip deformation-related loss of closure force. We aimed to investigate the impact of compression duration on SCI severity and the influence of clip deformation on closure force. Rats received T10-level clip-induced SCI with durations of 1, 5, 10, 20, and 30 s, and a separate group underwent T10 transection. Outcomes included functional, histological, electrophysiological assessments, and inflammatory cytokine analysis. A tactile pressure mapping system quantified clip closure force after open-close cycles. Our results showed a positive correlation between compression duration and the severity of functional, histological, and electrophysiological deficits. Remarkably, even a brief 1-s compression caused significant deficits comparable to moderate-to-severe SCI. SSEP waveforms were abolished with durations over 20 s. Decreased clip closure force appeared after five open-close cycles. This study offers critical insights into regulating SCI severity in rat models, aiding researchers. Understanding compression duration and clip fatigue is essential for experiment design and interpretation using the clip-induced SCI model.

Histological changes of vascular clipping in Wistar rats

Background

During aneurysm microsurgery, the aneurysmal sac is excluded from circulation by placing one or more clips at the base of the aneurysm. In some cases of complex aneurysms or subarachnoid hemorrhage history, transient clipping before definitive clipping is necessary. The closing force of the transient clip is less than the permanent clip; however, it is sufficient to stop circulation to the aneurysmal sac. The aim of the following work is to analyze and describe histological changes caused by transient and permanent clipping of the abdominal aorta in Wistar-type rats, to study the correlation between the closing force of the clip and the time, it remains on the vascular tissue structures.

Methods

Six groups were formed, with 10 rats each, whereby temporary clipping of the abdominal aorta was performed with subsequent sampling of the site where the vascular clip was placed. The groups were: control and temporary clipping with: 2, 5, 10, and 15 and permanent clipping with 5 min.

Results

Resection samples of the 3 μm thick aorta were obtained through the routine histological technique and special histochemical techniques (Masson's Trichrome and orcein) from the six groups. Transmural changes were found from Group II-VI.

Conclusion

There is a vascular histological effect after both transient and permanent clipping. The sum of time and strength of the clip induce vascular changes visible at 5 min.

Use of a microsurgical vascular clip system for temporary bilateral occlusion of the four main uterine vessels for laparoscopic enucleation of very large intramural uterine fibroids

Objectives

The goal of this study was to examine the safety, feasibility, and effectiveness of the use of a microsurgical temporary vascular clip system to facilitate the laparoscopic enucleation of very large intramural uterine fibroids.

Methods

In this retrospective study, the surgical outcomes of 26 patients who underwent laparoscopic myomectomy with temporary uterine vessel clipping for very large (the largest measured diameter ≥ 9 cm) symptomatic intramural uterine fibroids in two tertiary referral hospitals between September 2017 and March 2020 were examined. Titan-made vascular clips (YASARGIL^® Aneurysm Clip System) were used to temporarily occlude the bilateral uterine arteries and utero-ovarian vessels. Main outcomes included operating time, blood loss, number of leiomyomas and weight, conversion rate, intra- and postoperative complication rates, and length of hospital stay.

Results

Twenty six patients were included. Dominant intramural uterine fibroid diameters were 9–22 cm. The general characteristics of the patients were similar. The mean surgery duration and intraoperative blood loss were 175.3 ± 32.7 (range 120–250) min and 241.1 ± 103 (range 100–450) ml, respectively. The median postoperative drop in hemoglobin was 0.89 ± 0.75 g/dL. No patient required blood transfusion. No procedure was converted to laparotomy. No major intra- or postoperative complication occurred.

Conclusions

Laparoscopic myomectomy for very large intramural uterine fibroids can be performed safely and effectively, with less intraoperative blood loss, using vascular clips for temporary clamping of the bilateral uterine vessels.

Experimental animal studies of clip-induced microvascular trauma

This study was designed to evaluate microvascular clip potential for causing changes in vessel-wall tissue and the extent to which this potential is influenced by features of the clip. Light and scanning electron microscopy were used to examine vessel-wall changes after temporary clip occlusion. Vessel patency is shown to be influenced by anastomosis and clip site, changes in occlusion force due to material fatigue are described, and novel clip features to reduce vessel trauma are proposed. Evaluation of mechanical clip properties showed that material fatigue does not lead to relevant loss of precision in alpha-type clips. While the modified clip designed to reduce trauma cannot abolish trauma altogether, it significantly reduces the associated changes and hence the risk of thrombosis. Arteries were more sensitive than veins to clip-induced trauma, with increased occlusion force producing more severe damage than increased clipping time. Maximal changes were seen in the tunica media. These results indicate the paramount importance of applying modest clip pressure commensurate with the requirements of microvascular Surgery.

Basilar artery dissection: an early postoperative complication of aneurysm clipping. Case report

Recurrent subarachnoid hemorrhage (SAH) in the early period following successful clipping of a cerebral aneurysm is unusual. The authors report a unique case of distal basilar artery dissection and fatal SAH on the 6th day postoperatively. It is concluded that this complication was related to vascular trauma inflicted by repositioning the aneurysm clips during a seemingly uneventful procedure for a basilar artery tip aneurysm.

Temporary clipping in aneurysm surgery: technique and results

The use of temporary clipping has become an established tool in the armamentarium of the aneurysm surgeon. Our experience with 62 consecutive patients is presented, detailing operative protocols and results. Twenty-two had unruptured aneurysms (35%), 15 were grade I (24%), 16 grade II (25%), five grade III (8%), and four grade IV (7%). The aneurysms were mainly located in the middle cerebral artery (29 patients) and the anterior communicating artery (13 patients). Eleven of our 62 patients (17%) developed a new, persistent postoperative deficit. However, in only one case (2%) was temporary clipping felt to be implicated in the development of the deficit. In three other patients (5%), the effect of temporary clipping, although unlikely, could not be excluded. Overall, 92% of our patients with temporary clipping had good to excellent outcome, with 3% mortality and 5% morbidity. We believe that temporary clipping is a safe procedure that contributes significantly to a better outcome.

Reduced intimal injury to canine arteries with controlled application of vessel loops

Arterial intimal damage caused by elastic vessel loops was quantitated to determine (1) if they produce intimal injury, (2) if the injury is proportional to the force applied, and (3) if the injury is less than that produced by vascular clamps. Vessel loops were wrapped around 30 canine artery segments (5 mm in diameter) and a gram scale was connected to each to measure the force applied. The minimal occlusive force (MOF) and 150, 200, and 250 g force were applied for 30 min. For comparison, a Fogarty vascular clamp was applied at MOF for 30 min. Arteries were then reperfused for 30 min. Half was immediately harvested (group I); the remaining half was harvested at 2 weeks (group II). Scanning electron micrographs were made of each artery's intimal surface and graded from 0 (no injury) to 5 (severe intimal fracture). Mean injury grades were calculated. The MOF for vessel loops was 99 g. In group I, arteries subjected to less than 200 g force had a mean injury grade of 1.0 +/- 0.4; while those exposed to 200-250 g force had an injury grade of 3.5 +/- 0.7. The severity of injury was linearly correlated with the force applied (r = 0.72, P less than 0.009). In group II, the injury grade of 0.4 +/- 0.5 in arteries at MOF was significantly less than the injury grade of 2.8 +/- 0.5 in those at 200-250 g force, (P less than 0.0005). Injury grades of 3.7 and 3 were seen in groups I and II, respectively, when Fogarty clamps were applied. We conclude that vessel loops applied at MOF produce minimal injury. At greater occlusive forces, the injury is proportional to the force applied approaching that of a Fogarty clamp. Intimal injuries may be minimized when vessel loops are applied at MOF.

Current management of cerebral aneurysms: is it based on facts or myths?

The overall morbidity and mortality from aneurysmal subarachnoid hemorrhage have not changed significantly over the past 30 years in spite of great progress in surgical technology and diagnostic capabilities. Most series report major morbidity and mortality figures of approximately 60%. The reason for the currently poor prognosis is due, in part, to the sometimes devastating effect of the initial hemorrhage over which we have no control. Another reason for our inability to improve these dismal statistics may be that the currently accepted treatment regimens have proven to be ineffective. Eighteen misconceptions or "myths" surrounding the treatment of aneurysmal subarachnoid hemorrhage have been identified as factors that have largely determined the currently accepted, ineffective treatment protocols, and these are discussed.

New disposable microvascular clamp

A new design for a plastic microvascular clamp is described. The clamp consists of two flat blades, with eyes permitting application and removal of the clamp with cross-forceps. Closure is effected by the elasticity of a rubber ring placed around the blades, obviating the need for an articular joint or a spring mechanism. The new design simplifies production of the clamp, which is intended to be disposable, i.e., for once-only use.

Mechanical and metallurgical properties of vascular clips designed for temporary use

Six commonly used surgical clips (Kleinert-Kutz, Pivot, Vari-Angle, Yasargil, Biemer, and Acland) that have been designated by their manufacturer as being suitable for temporary occlusion were studied in terms of their mechanical and metallurgical properties. Opening and closing forces were determined for all of the clips. Significant variations in clip force with respect to blade gap were found in all of the pivot-type clips. Metallurgical testing showed that all six clips exhibited properties that contraindicate long-term implantation.