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

BACKGROUND: Secure vessel occlusion is critical to the success of all surgical and interventional procedures. The purpose of this study was to compare in vivo the use of the Amsel Vessel Occluder (AVO), a novel occlusion clip device for secure blood vessel closure, with one of the many commercially available hemoclips, the Ligaclip, in the porcine model. METHODS: Vessel closure of arteries and veins was performed on 10 swine to compare the ease of use, safety, and efficacy of the AVO with the Ligaclip as well as the tissue response at 7 and 30 d. After heparinization, the targeted vessels (carotid/femoral/brachial arteries and jugular/femoral/brachial veins) were occluded with two clips, either two AVO's or two Ligaclip's, and the vessels transected between the two clips. Any bleeding was recorded. At sacrifice, gross and histopathologic findings were examined for evidence of bleeding or injury to adjacent structures. The tissue response and healing were evaluated by a prospective randomized histopathologic study for the effects of any biological incompatibilities. At time of sacrifice, occluded vessel segments were subjected to nonphysiological pressures ("holding" pressures) to compare efficacy of occlusion in fresh, nonoccluded vessels, and the ability to dislodge the clips once applied. RESULTS: Twenty veins and 20 arteries between 2-mm and 7-mm outer diameter were occluded in 10 pigs. Each vessel was occluded with either AVO or Ligaclip. Our study confirmed easy and safe AVO application with no dislodgment of any AVO clips once deployed. The AVO showed no intraoperative or postoperative bleeding (AVO = 0/40), while one Ligaclip dislodged resulting in a fatal hemorrhage 16 h after surgery (Ligaclip = 1/40), and on two occasions where, with obvious slippage of the Ligaclip, immediately after deployment, additional clips were placed. The holding pressures for the two clips were similar but unlike the AVO, the Ligaclip was easily dislodged. Histopathologic examination showed no difference in the tissue response and healing of the two clips. CONCLUSIONS: The AVO is simple to deploy and securely maintains occlusion by transfixing the targeted vessel, unlike the widely used, nontransfixing Ligaclip, that has a tendency to dislodge. As such, the Amsel secure vessel occluder opens up numerous treatment opportunities in both the venous and arterial systems to minimize open, laparoscopic, robotic surgical and interventional procedures, and reduce patient morbidity and its associated health care costs.

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.

The relationship between genus richness and geographic area in Late Cretaceous marine biotas: epicontinental sea versus open-ocean-facing settings.

For present-day biotas, close relationships have been documented between the number of species in a given region and the area of the region. To date, however, there have been only limited studies of these relationships in the geologic record, particularly for ancient marine biotas. The recent development of large-scale marine paleontological databases, in conjunction with enhanced geographical mapping tools, now allow for their investigation. At the same time, there has been renewed interest in comparing the environmental and paleobiological properties of two broad-scale marine settings: epicontinental seas, broad expanses of shallow water covering continental areas, and open-ocean-facing settings, shallow shelves and coastlines that rim ocean basins. Recent studies indicate that spatial distributions of taxa and the kinetics of taxon origination and extinction may have differed in these two settings. Against this backdrop, we analyze regional Genus-Area Relationships (GARs) of Late Cretaceous marine invertebrates in epicontinental sea and open-ocean settings using data from the Paleobiology Database. We present a new method for assessing GARs that is particularly appropriate for fossil data when the geographic distribution of these data is patchy and uneven. Results demonstrate clear relationships between genus richness and area for regions worldwide, but indicate that as area increases, genus richness increases more per unit area in epicontinental seas than in open-ocean settings. This difference implies a greater degree of compositional heterogeneity as a function of geographic area in epicontinental sea settings, a finding that is consistent with the emerging understanding of physical differences in the nature of water masses between the two marine settings.

Multimodal spectroscopy detects features of vulnerable atherosclerotic plaque.

Early detection and treatment of rupture-prone vulnerable atherosclerotic plaques is critical to reducing patient mortality associated with cardiovascular disease. The combination of reflectance, fluorescence, and Raman spectroscopy-termed multimodal spectroscopy (MMS)-provides detailed biochemical information about tissue and can detect vulnerable plaque features: thin fibrous cap (TFC), necrotic core (NC), superficial foam cells (SFC), and thrombus. Ex vivo MMS spectra are collected from 12 patients that underwent carotid endarterectomy or femoral bypass surgery. Data are collected by means of a unitary MMS optical fiber probe and a portable clinical instrument. Blinded histopathological analysis is used to assess the vulnerability of each spectrally evaluated artery lesion. Modeling of the ex vivo MMS spectra produce objective parameters that correlate with the presence of vulnerable plaque features: TFC with fluorescence parameters indicative of collagen presence; NC∕SFC with a combination of diffuse reflectance ß-carotene∕ceroid absorption and the Raman spectral signature of lipids; and thrombus with its Raman signature. Using these parameters, suspected vulnerable plaques can be detected with a sensitivity of 96% and specificity of 72%. These encouraging results warrant the continued development of MMS as a catheter-based clinical diagnostic technique for early detection of vulnerable plaques.

Epicontinental seas versus open-ocean settings: the kinetics of mass extinction and origination.

Environmental perturbations during mass extinctions were likely manifested differently in epicontinental seas than in open-ocean-facing habitats of comparable depth. Here, we present a dissection of origination and extinction in epicontinental seas versus open-ocean-facing coastal regions in the Permian through Cretaceous periods, an interval through which both settings are well represented in the fossil record. Results demonstrate that extinction rates were significantly higher in open-ocean settings than in epicontinental seas during major mass extinctions but not at other times and that origination rates were significantly higher in open-ocean settings for a protracted interval from the Late Jurassic through the Late Cretaceous. These patterns are manifested even when other paleogeographic and environmental variables are held fixed, indicating that epicontinental seas and open-ocean-facing coastlines carry distinct macroevolutionary signatures.

Phanerozoic trends in the global diversity of marine invertebrates.

It has previously been thought that there was a steep Cretaceous and Cenozoic radiation of marine invertebrates. This pattern can be replicated with a new data set of fossil occurrences representing 3.5 million specimens, but only when older analytical protocols are used. Moreover, analyses that employ sampling standardization and more robust counting methods show a modest rise in diversity with no clear trend after the mid-Cretaceous. Globally, locally, and at both high and low latitudes, diversity was less than twice as high in the Neogene as in the mid-Paleozoic. The ratio of global to local richness has changed little, and a latitudinal diversity gradient was present in the early Paleozoic.

In vivo Raman spectral pathology of human atherosclerosis and vulnerable plaque.

The rupture of vulnerable atherosclerotic plaque accounts for the majority of clinically significant acute cardiovascular events. Because stability of these culprit lesions is directly related to chemical and morphological composition, Raman spectroscopy may be a useful technique for their study. Recent developments in optical fiber probe technology have allowed for the real-time in vivo Raman spectroscopic characterization of human atherosclerotic plaque demonstrated in this work. We spectroscopically examine 74 sites during carotid endarterectomy and femoral artery bypass surgeries. Of these, 34 are surgically biopsied and examined histologically. Excellent signal-to-noise ratio spectra are obtained in only 1 s and fit with an established model, demonstrating accurate tissue characterization. We also report the first evidence that Raman spectroscopy has the potential to identify vulnerable plaque, achieving a sensitivity and specificity of 79 and 85%, respectively. These initial findings indicate that Raman spectroscopy has the potential to be a clinically relevant diagnostic tool for studying cardiovascular disease.

Increased longevities of post-Paleozoic marine genera after mass extinctions.

Cohorts of marine taxa that originated during recoveries from mass extinctions were commonly more widespread spatially than those originating at other times. Coupled with the recognition of a correlation between the geographic ranges and temporal longevities of marine taxa, this observation predicts that recovery taxa were unusually long-lived geologically. We analyzed this possibility by assessing the longevities of marine genus cohorts that originated in successive substages throughout the Phanerozoic. Results confirm that several mass extinction recovery cohorts were significantly longer lived than other cohorts, but this effect was limited to the post-Paleozoic, suggesting differences in the dynamics of Paleozoic versus post-Paleozoic diversification.

A multicenter study of permanent hemodialysis access patency: beneficial effect of clipped vascular anastomotic technique.

OBJECTIVE: There is an urgent and compelling need to reduce the morbidity and expense of maintaining hemodialysis vascular access patency. This large, long-term, retrospective, multicenter study, which compared access patency of autogenous arteriovenous fistulas (AVF) and synthetic bridge grafts (AVG) created with conventional sutures or nonpenetrating clips, was undertaken to resolve conflicting results from previous smaller studies. DESIGN: Patency data for 1385 vascular access anastomoses (clipped or sutured) was obtained from 17 hospitals and dialysis centers (Appendix). Five hundred eighteen AVF (242 clip, 276 suture) and 827 AVG (440 clip, 384 suture) were analyzed. Statistical comparisons were made with Kaplan-Meier survival analysis, log-rank test, two-sample t test, and X(2) test. The Cox proportional hazards model was used to confirm Kaplan-Meier analysis. RESULTS: Access patency (primary, secondary, overall, and intention to treat) was significantly improved in access anastomoses constructed with clips. In the intention-to-treat group, primary patency at 24 months was 0.54 for clipped AVF and 0.34 for sutured AVF, and was 0.36 for clipped AVG and 0.17 for sutured AVG. At 24 months, primary patency rate for AVF successfully used for dialysis was 0.67 for clips and 0.48 for sutures, and for AVG was 0.39 for clips and 0.19 for sutured constructs. Interventions necessary to maintain patency were significantly fewer in clipped anastomoses. CONCLUSION: Replacing conventional suture with clips significantly reduces morbidity associated with maintaining permanent hemodialysis vascular access. This beneficial effect may be due to the biologic superiority of interrupted, nonpenetrating vascular anastomoses.

Recommended standards for reports dealing with arteriovenous hemodialysis accesses.

The incidence rate of treated end-stage renal disease in the united states is 180 per million and continues to rise at a rate of 7.8% per year. Arteriovenous hemodialysis access (AV access) creation and maintenance are two of the most difficult issues associated with the management of patients on hemodialysis. The 1-year complication rate of a primary prosthetic AV access for hemodialysis ranges from 33% to 99%. Various investigators report on patency and complications of AV access. However, it is rather difficult to compare outcomes because of the wide variety of access materials, configurations, locations, risk factors, and quality of inflow and outflow vessels. Although there have been reporting standards for dialysis access endovascular interventions and for central venous access placement, standards regarding surgical access placement and its revision are lacking. The "Dialysis Outcome Quality Initiative," published by the National Kidney Foundation, provides recommendations for optimal clinical practices aimed at improving dialysis outcome and patient survival. This reporting standards document is not meant to be a "practice guidelines" or "best practices" document. Rather, the purpose of this document is to provide standardized definitions related to AV access procedures and to recommend reporting standards for patency and complications, to be used by surgeons, nephrologists, and interventional radiologists, that will permit meaningful comparisons among AV access procedures. The terms, definitions, and categories featured in this article have been approved by the Committee on Reporting Standards of the Society for Vascular Surgery and the American Association for Vascular Surgery and should be observed in preparing manuscripts on AV accesses for submission to the Journal Of Vascular Surgery.