Functional repair of the great saphenous vein by external valvuloplasty reduces the vein's diameter: 6-month results of a multicentre study.

OBJECTIVES: External valvuloplasty (eVP) is a reconstructive surgical method to repair the function of the terminal and preterminal valves. We evaluated the 6-month outcomes of eVP regarding the diameter of the great saphenous vein (GSV). METHODS: Patients from five vein centres were included in this observational study. Follow-up involved detailed duplex sonography of the GSV. The venous clinical severity score (VCSS) and the C class of the clinical, aetiologic, anatomic and pathophysiologic (CEAP) classification were recorded. RESULTS: We enrolled 210 patients, with a follow-up rate of 58%; eVP was sufficient in 95.24% of the patients. The GSV diameters decreased significantly from 4.4 mm (standard deviation (SD): 1.39) to 3.9 (SD: 1.12), 4 cm distal to the saphenofemoral junction (SFJ); from 3.7 mm (SD: 1.10) to 3.5 mm (SD: 1.02) at the mid-thigh; from 3.6 mm (SD: 1.14) to 3.3 mm (SD: 0.94) at the knee and from 3.1 mm (SD: 0.99) to 2.9 mm (SD: 0.78) at the mid-calf. VCSS decreased significantly from 4.76 (SD: 2.13) preoperatively to 1.77 (SD: 1.57) 6 months postoperatively. CONCLUSIONS: GSV function can be restored by eVP; diameters over the total length of the GSV decreased significantly.

External valvuloplasty of the saphenofemoral junction in insufficient great saphenous veins - six weeks results of a prospective multicentre trial.

Background: Varicosis of the great saphenous vein (GSV) is a common disease. Most of the therapeutic concepts attempt to remove or destroy the truncal vein. However, the absence of the GSV could be harmful for further treatments of artherosclerotic disease as the GSV is often used as bypass graft in lower extremity or coronary artery revascularisations. External valvuloplasty (EV) is one of the vein-sparing treatment options. The aim of this clinical study was to describe the outcome, safety and complications of this procedure in a prospective multicentre trial. Patients and methods: The function of the terminal and preterminal valve was restored by external valvuloplasty. Furthermore, multiple phlebectomies of tributaries were performed. Patients were reinvestigated six weeks after surgery. Primary endpoint was the function of the external valvuloplasty measured by diameter of the GSV and the prevalence of reflux in the GSV. The eligibility of the vein as a potential bypass graft was noticed. CEAP class and VCSS scores were analysed. Results: A total of 359 patients were included in the study. After six weeks 297 patients could be reinvestigated. The function of the external valvuloplasty was sufficient in 284 patients (95.6%). Treatment failed in 8 patients (2.6%) due to an occlusion or junctional reflux despite valvuloplasty. The GSV was estimated as suitable as a bypass graft in 261 patients (87.8%). Reflux at the saphenofemoral junction was significantly reduced after treatment and the diameter of the GSV near the saphenofemoral junction significantly decreased from 4.4 mm to 3.8 mm (p < 0.05). The VCSS was significantly reduced from 4.6 preoperatively to 2.6 postoperatively. Conclusions: External repair of the great saphenous vein can reduce venous symptoms and may preserve the great saphenous vein as a bypass graft. Nevertheless, this treatment option is only suitable for a limited number of patients.

Barrier Patch Implantation during Redo Surgery for Varicose Vein Recurrences in the Groin: 1-Year Results.

BACKGROUND: Rerecurrences after redo surgery for recurrent varicose veins in the groin are a common problem. The present report looks at the efficacy of an additional barrier patch implantation in reducing these rerecurrences. METHODS: A retrospective review of a prospectively collected database was conducted. This included 67 patients with 86 legs who underwent redo-groin surgery for symptomatic recurrences. In addition, a polytetrafluoroethylene-barrier patch was placed at the former saphenofemoral junction. All patients had undergone ligation and stripping of the great saphenous vein a mean of 13.9 years earlier. All patients were examined by duplex ultrasound before and 1 year after the procedure. RESULTS: Perioperatively, minor complications occurred in 5.8% of cases, the groin infection rate was 2.4%. In 85 of 86 legs, the duplex follow-up examination was performed after 1 year. This revealed an overall rerecurrence rate of 12%, of which only 2.4% were caused by recurrent neovascularization in the groin bypassing the barrier patch. The remaining 9.6% were caused by different sites of reflux (pelvic veins and perforators). CONCLUSIONS: Redo-groin surgery with additional barrier patch implantation seems to be a safe and effective way to prevent rerecurrences in the groin. In our experience, it provided very promising 1-year results with a very low rate of recurrent neovascularization.

Transcranial ultrasound perfusion imaging and perfusion-MRI--a pilot study on the evaluation of cerebral perfusion in severe carotid artery stenosis.

Severe internal carotid artery stenosis can cause constriction of cerebral perfusion. Different techniques of measuring brain perfusion are currently available. Ultrasound perfusion imaging (UPI) can differentiate hypoperfused and nonperfused cerebral tissue. Aim of this study was to compare the value of UPI and perfusion-weighted magnetic resonance imaging (pw-MRI) in the evaluation of cerebral perfusion in patients with severe internal carotid artery stenosis. Ten patients with severe internal carotid artery stenosis were included. UPI was performed with phase-inversion-harmonic-imaging and bolus application of contrast media for semiquantitative analysis of time-intensity curves. Time-to-peak intensity (TPI) values were compared with time-to-peak maps of pw-MRI examinations in predefined regions-of-interest (ROI). Further, a comparison of pre- and postoperative UPI data was performed in selected cases. Seven of 10 patients could be evaluated. Eighty ROIs were used for the comparison of UPI and pw-MRI, 37 ROIs were used for pre- and 36 ROIs for postoperative comparison of UPI data. There was no delay in any MRI ROI. In UPI, there were relevant delays in seven of 37 ROIs (18.9%) before and in nine of 36 ROIs (25.0%) after surgery. Eleven of these 16 ROIs (68.8%) were in the inner border zone. Compared with the established pw-MRI technique, UPI described possible subtle perfusion delays mainly of the inner border zone. These preliminary results suggest a possible diagnostic power of UPI as a noninvasive tool for the detection of hemodynamic relevance in severe internal carotid artery disease.

Validity of duplex-ultrasound in identifying the cause of groin recurrence after varicose vein surgery.

INTRODUCTION: Often groin recurrences after varicose vein surgery are diagnosed and classified with the help of a duplex ultrasound scan. There are, however, no studies indicating if duplex ultrasound scans can reliably distinguish between the different forms of recurrent vessels, ie, neovascularization or a residual stump. To address this issue, we have conducted a prospective study in which ultrasound scan assessment of groin recurrences was compared to the histological classification of the recurrent groin veins. MATERIALS AND METHODS: All patients undergoing redo-surgery for symptomatic groin recurrences after previous stripping of the greater saphenous vein (GSV) during a 1-year period (May 2006-May 2007) were included in the study. Preoperatively, all patients had a duplex-ultrasound scan examination of the groin vessels. Based on the duplex scan findings, the recurrent veins in the groin were classified as either a residual stump or neovascularization. During the redo-surgery, a specimen of the recurrent groin veins was obtained and underwent histologic evaluation. Based on histologic criteria, the recurrence was also classified as a residual stump or neovascularization. RESULTS: During the 1-year study period, 125 groin recurrences in 95 consecutive patients (74 female, 21 male, mean age 58.7 years, standard deviation [SD] 10.3 years) were included. In the 119 cases where both duplex-ultrasound scan and histological evaluation were available, a residual stump was seen at the histological examination in 80.7% of cases, a neovascularization in 10.9% of cases, and a combination of both entities in 8.4% of cases. Duplex-ultrasound scan classified the recurrent groin veins as a residual stump in 68.1% of cases, as neovascularization in 26.1%, and as a combination of both in 5.8% of cases. With histological classification as the gold-standard, duplex ultrasound scans reached a sensitivity of 77.1% and a positive predictive value of 91.4% in correctly identifying a residual stump as the cause of recurrence. For the correct classification of neovascularization, sensitivity was 61.5% and the positive predictive value 25.8%, while a combination of both was recognized with a sensitivity of 10% and a positive predictive value of 14.3%. CONCLUSION: While duplex-ultrasound scan is a reliable tool to diagnose groin recurrences after varicose vein surgery, its validity in classifying the different types of recurrent groin vessels is limited. Especially the correct identification of neovascularization which is poor with a sensitivity of 62% and a positive predictive value of 26%. Histological examination should still be regarded as the gold-standard when trying to differentiate between different types of groin recurrences.

Exocrine pancreas disfunction in severely traumatised patients and early enteral nutrition.

BACKGROUND: We investigated exocrine pancreatic insufficiency in severely traumatised patients with enteral nutrition using the fecal elastase-1 concentration. METHODS: The fecal elastase-1 levels of critically ill patients after major trauma (n=18) were determined in a prospective study. Early enteral nutrition was started with a high molecular diet via a naso-duodenal tube, starting 24-36 hours after admission to the intensive care unit. Enteral feeding was administered continuously starting with 20 mL/h (1 kcal/mL) and advanced gradually to 80 mL/h in the next days. Stool samples from the first and second stool after beginning of the enteral nutrition were taken for determination of the fecal elastase-1. For elastase-1 analysis in a sandwich-type enzyme immunoassay (ELISA), a sample of approximately 1 g stool was taken from the first and second stool after beginning of the enteral nutrition. Elastase-1 concentration of >200 microg/g was considered as normal, whereas <100 microg/g elastase-1 was significantly low indicating a severe exocrine pancreas dysfunction. RESULTS: All patients were fed enterally without relevant feeding-associated complications and no diarrhoea occurred in any patient. In the initial stool passage, 55.6% of the patients had moderately or severely decreased elastase-1 concentrations. In the second stool passage, only 38.9% of the patients showed a decrease in the elastase-1 concentration (p<0.01). The average elastase-concentration in the first stool sample was 268.4 microg/g (median: 162.1 microg/g) and in the second sample 333.8 microg/g (median: 520.2 microg/g). CONCLUSION: The data of this study suggests that initial exocrine pancreas insufficiency may occur in severely traumatised and critically ill patients, which improves under early enteral nutrition with polymeric enteral diets. The clinical consequences of exocrine pancreatic dysfunction in the early posttraumatic situation have to be defined.

A case of contained ruptured aortitis due to Clostridium septicum infection in a patient with a colon malignancy.

We discuss a case of contained ruptured aortitis due to Clostridium septicum infection in a 71-year-old man, who had undergone a right hemicolectomy and cholecystectomy to treat an ascending colon carcinoma. Computed tomography identified a juxtarenal abdominal aneurysm with gas formation in the right psoas muscle. Emergency abdominal exploration revealed a ruptured aortitis. After in situ graft replacement of the abdominal aorta, Clostridium septicum was identified in tissue culture. Antibiotic therapy with penicillin G was administered. The postoperative course was complicated by a retroperitoneal haematoma which necessitated surgical revision. The patient was discharged 2 months afterwards. At clinical monitoring at 6 months he is still doing well.

Reflux patterns in the ovarian and hypogastric veins in patients with varicose veins and signs of pelvic venous incompetence.

Patients with varicose veins who also had clinical and/or duplex ultrasound findings suspicious of pelvic venous incompetence (PVI) underwent selective retrograde catheter phlebography of the pelvic veins. One hundred and one patients (all female, mean age 49.3 years) underwent selective phlebography of the pelvic veins. In 68 cases (67.3%) a varicose vein recurrence after previous stripping of the greater saphenous vein was present, and about half the patients (n=45, 44.6%) were multipara ( > or =2 episodes of childbirth). The presence and extent of any reflux was documented and the ovarian and pelvic veins affected by the reflux were recorded. Retrograde selective phlebography demonstrated a PVI in 75 patients (74.2%). The left ovarian vein and the right hypogastric vein were most frequently affected by reflux (n = 41, 54.6% each). The left hypogastric vein was incompetent in 35 patients (46.6%) and the right ovarian vein in 3 cases (4%). In about half the patients with pelvic venous incompetence, reflux was demonstrated in more than one of the main pelvic veins (n=38, 50.6%). Fifty-one (68%) of the 75 patients with pelvic venous incompetence had varicose vein recurrence after previous stripping of the greater saphenous vein. Extension of the reflux into varicose veins of the groin or lower leg was demonstrated in 44 patients (58.6%). Thirty-nine patients (52%) received treatment for their pelvic venous incompetence (coil embolisation, sclerotherapy or videoscopic ovarian vein ligation). Pelvic venous reflux was present in 75% of our study population. Combined reflux in more than one pelvic vein was common and in about 60% of cases the pelvic reflux was shown to feed varicose veins of the legs. Therefore, typical clinical and/or duplex findings should lead to a strong suspicion of pelvic venous incompetence and reduce the need for selective retrograde catheter phlebography in this selected group of patients.

Different approaches in the treatment of cystic adventitial disease of the popliteal artery.

Three cases of cystic adventitial disease (CDA) of the popliteal artery and the results of a literature review are described in order to identify the treatment of first choice of this rare clinical entity. Three male patients (mean age 56,3 years) presented at our Institution due to a sudden abrupt of disabling claudication of the lower limb. The eco-color-Doppler examination showed multiple hypoechoic and anechoic masses arising in the wall of the artery consistent with CAD. The magnetic resonance imaging (MRI) confirmed this finding. In 2 cases a venous interposition grafting was performed and in the remaining patient a duplex-directed punction. The 3 patients are asymptomatic at the clinical control at 9 months after treatment. As it results after a literature review, the MRI seems to be the best diagnostic tool and the vein interposition grafting the treatment of first choice. In cases of young male patients without cardiovascular risk factors and suffering of disabling claudication of recent onset the MRI guarantees a valuable diagnosis in case of ultrasonographic suspect of CAD of the popliteal artery. The surgical resection and the vein interposition grafting represent the treatment of first choice. In selected patients, a duplex-guided punction assures satisfactory clinical results. A strict ultrasonographic follow-up guarantees an early recognition of relapse.

Supplementation of omega-3 fatty acids in parenteral nutrition beneficially alters phospholipid fatty acid pattern.

BACKGROUND: The clinical safety and the uptake of omega-3 polyunsaturated fatty acids (PUFA) into the serum phospholipids and erythrocyte membranes after administration of fish-oil-supplemented parenteral nutrition (PN) was investigated in colorectal surgical patients. METHODS: Forty patients undergoing colorectal surgery (n = 40) and with an indication for PN were enrolled in a prospective, double-blind, randomized study to receive an omega-3 PUFA-supplemented 20% lipid emulsion (Lipoplus; B. Braun Melsungen, Melsungen, Germany; test group, n = 19) for 5 days postoperatively. The control group received a standard 20% fat emulsion (Lipofundin MCT/LCT, B. Braun Melsungen, Melsungen, Germany, control group, n = 21). Clinical outcome parameters and safety were assessed by means of adverse events recording clinical parameters and hematologic analyses. The contents of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), as well as arachidonic acid (AA), in phospholipid fractions in plasma and in erythrocytes were analyzed preoperatively, on postoperative days 1, 6, and 10 using liquid gas chromatography. RESULTS: Both fat emulsions were well tolerated, and none of the adverse events was considered to be related to treatment. Postoperative infectious complications occurred in 4 patients of the omega-3 PUFA group vs 7 patients in the control group. As compared with the control group, the omega-3 PUFA group had significantly increased levels of EPA in the membranes of the erythrocytes in postoperative day 6 (2.0% +/- 0.9% vs 0.8% +/- 0.5% fatty acid methyl esters, [FAME]) and postoperative day 10 (2.1% +/- 0.8% vs 0.9% +/- 0.7% FAME, p < .05). Also, the EPA levels in the serum phospholipids were significantly higher than in the control group on the same postoperative days (7.0% +/- 2.6% vs 1.3% +/- 0.8% and 3.6% +/- 1.0% vs 1.0% +/- 0.4% FAME, p < .05). The DHA levels in the serum phospholipids were significantly higher in the omega-3 PUFA group compared with the control on postoperative days 6 and 10 (11.8% +/- 1.9% vs 8.4% +/- 1.5% and 11.2% +/- 1.6% vs 8.5% +/- 1.4% FAME, p < .05). AA levels were not significantly different in the both groups. CONCLUSIONS: Omega-3-fatty-acids-supplemented fat emulsions for parenteral administration are safe and very well tolerated. This study demonstrates that parenteral administration of omega-3-PUFA-enriched fat emulsions leads to increased incorporation of EPA and DHA into phospholipids in serum and erythrocytes, whereas AA levels remain unchanged. Thus, postoperative parenteral administration of omega-3-PUFA-enriched lipid emulsions could have an impact on the postoperative inflammatory response after abdominal surgery and could be used in standard postoperative care when PN is indicated.

Factors influencing early results and complication rates of the thrombolytic treatment of lower limb ischemia with recombinant tissue-type plasminogen activator.

The aim of the study was to determine the effect of comorbidity conditions on the early outcome and complication rates of thrombolytic treatment of lower limb ischaemia with recombinant tissue plasminogen activator (rt-PA). Clinical and procedural data of 82 patients treated for acute/subacute arterial/graft occlusion were analysed retrospectively. Early results and adverse events were recorded and evaluated statistically. Early resolution of ischemic symptoms was achieved in 67 (82%) patients with a median dose of 25.4 mg of rt-PA. Major bleeding was reported in 9 and minor bleeding in 6 cases (intracranial hemorrhage rate 1%, mortality rate 1%, major amputation rate 1%). Comorbidity conditions and patient characteristics did not statistically influence success and complication rates. Bleeding was observed in patients who received a higher dose of the thrombolytic agent (30.0 mg vs 24.3 mg). Comorbidity conditions have no effect on early outcome and adverse events after thrombolytic management of lower limb ischemia. Higher doses of rt-PA with prolonged infusion times increase the risk of occurrence of treatment-related bleeding.

[Management of infected vascular grafts. Are there any factors predictive of early clinical success?]. / Management delle infezioni protesiche vascolari. Esistono variabili predittive di successo precoce?

The aim of the study was to define mortality and limb loss rates and to identify factors predictive of early clinical success in the management of infected vascular grafts. Clinical data of 40 patients were reviewed, evaluating comorbidity factors, laboratory findings, ischaemic symptoms, graft material and time of onset of infections. Diabetes and chronic renal insufficiency were reported in 15% of cases, malignancy in 10%, pathological C-reactive protein in 77.5% and leukocytosis in 60%. 52.5% of the patients presented with a disabling claudication, and 77.5% with an infected alloplastic graft. Early infection had developed in 57.5%. A total graft excision was performed in 72.5% of cases. Early complications were recorded in 32.5% of the patients, with a limb loss rate of 22.5% and a mortality rate of 10%. Total graft excision is the treatment of first choice in patients with an infected vascular graft. Patients presenting with critical ischaemia and early septic complications will experience poor clinical results in terms of limb loss and mortality. Pathological blood levels of C-reactive protein could help in the choice of treatment in unclear cases.

Central perineal hernia mimicking rectocele: a case report.

BACKGROUND: A perineal hernia is a very rare clinical finding. Three forms are distinguished: anterior, posterior, and central. Diagnosis of the last one is difficult, and sometimes, it is falsely named a posterior rectocele. AIM: This work presents a successfully treated case of central perineal hernia and makes a brief summary of existent literature on the problem. PRESENTATION OF THE CASE: We report of a 67-year-old female patient with a symptomatic central pelvic floor hernia. After radiological confirmation of the diagnosis, a transperitoneal approach was chosen to reposition the protruded segment of the small bowel. The hernial orifice was closed by extraperitoneal implantation of a polypropylene mesh. DISCUSSION: In the present case, the use of a laparoscopic technique seemed unsuitable due to the extension of the findings. For the repair of perineal hernia, we followed the principles of the "tension-free" concept. If there are no signs of a pelvic floor infection and if the mesh can be implanted totally extraperitoneally, we recommend the use of nonabsorbable alloplastic material (polypropylene) for reinforcement of the pelvic floor as a suitable technique for the repair of large perineal hernias.

Ultrasound elastography for the age determination of venous thrombi. Evaluation in an animal model of venous thrombosis.

The exact age determination of venous thrombi is important if thrombolytic therapy or surgical thrombectomy is considered. Clinical symptoms as well as duplex-ultrasound and phlebography are unreliable in this respect and do not allow an exact age estimation. Ultrasound elastography can provide information about the elastic properties of thrombi. Since thrombus elasticity decreases with age due to the organisation process, it should be possible to use elastography to stage the degree of organisation and thereby determine the age of venous thrombi. Experimental venous thrombi aging 1, 3, 6, 9, 12 and 15 days were created in a porcine model by laparoscopic ligation of the infrarenal Vena cava in combination with transfemoral infusion of thrombin. The thrombosed iliac veins were explanted and embedded in gelatine, after that they underwent examination by ultrasound elastography. In addition, histological evaluation of the thrombi was performed. Elastography demonstrated a decline in thrombus elasticity between days 6 and 12 with the 12-day-old thrombi being about 3 times harder then the 6-day-old thrombi. This correlated with the histological findings, which demonstrated a marked increase in fibroblast and collagen production in the clots during this time, with the 12- and 15-day thrombi showing signs of advanced organisation. In conclusion, in an experimental setting, ultrasound elastography was helpful in determining the exact age of venous thrombi. The differences in elasticity were most pronounced between days 6 and 12, which is also the most relevant time frame when considering invasive therapies in human venous thrombosis.

Validity of the macroscopic identification of neovascularization at the saphenofemoral junction by the operating surgeon.

PURPOSE: The intraoperative classification of recurrent veins at the saphenofemoral junction as neovascularization is based on certain macroscopic criteria. The validity of this neovascularization identification by the surgeon was evaluated by histologic and immunohistochemical examinations of the resected veins as the gold standard. METHODS: One hundred-four patients (mean age 57 +/- 10.9 years) with 130 affected extremities underwent redo surgery of the saphenofemoral junction for recurrent varicose veins at a mean of 12.0 +/- 7.9 years after the initial stripping of the greater saphenous vein. The surgeon used intraoperative findings to classify the recurrent veins as neovascularization (group A), no neovascularization (group B), or unclear findings (group C). The resected veins then underwent histologic and immunohistochemical examinations and were again classified into the same three groups (a, neovascularization; b, no neovascularization; c, unclear) according to the histologic results. RESULTS: The operating surgeon correctly recognized 16 (41%) of 39 histologically proven neovascularizations, whereas 22 (56%) were not identified. In contrast, 66 (84%) of 79 cases with no neovascularization were correctly identified during the operation. A definite classification by macroscopic criteria was not possible in 4 cases (3%) and the histologic examinations revealed unclear findings in 12 cases (9%). The macroscopic neovascularization identification had a sensitivity of 42.1% and a specificity of 85.7%. The positive predictive value reached 59.3% and the negative predictive value, 75%. CONCLUSION: The validity of intraoperative neovascularization identification is poor, but the surgeon is able to recognize non-neovascularization recurrences with relatively high accuracy. The etiologic classification of recurrent veins at the saphenofemoral junction should not be solely based on macroscopic criteria.

Regional hyperthermic fibrinolytic perfusion after unsuccessful venous thrombectomy of extensive deep venous thrombosis.

OBJECTIVE: Because of the dose-dependent increase in bleeding complications, the intraoperative administration of fibrinolytic agents is limited. This limitation impairs the efficacy of fibrinolytic therapy because low-dose fibrinolysis often fails in the treatment of complex deep venous thrombosis (DVT). The aim of this study was to investigate the efficacy and safety of intraoperative high-dose fibrinolytic therapy for extended DVT, which was performed with the regional hyperthermic fibrinolytic perfusion (RHFP) technique. METHODS: From January 1993 to June 2001, in 53 patients with extended DVT, unsuccessful venous thrombectomy (recanalization, <50%) was followed by RHFP with 0.5 mg/kg of body weight of recombinant tissue plasminogen activator. The extent of thrombosis was documented before, during (after the surgical thrombectomy), and after (between postoperative days 2 and 5) surgery with phlebography and was quantified with the Marder score. Intraoperative and postoperative complications were recorded prospectively. RESULTS: After RHFP, a recanalization was achieved in 64 of 146 venous segments (43.8%) that were still occluded despite thrombectomy. Eighty-two segments (56.2%) remained occluded. Compared with the preoperative phlebography, 32 patients (60.3%) had a successful recanalization (>50%). Eleven patients (20.8%) showed minimal and 10 patients (18.9%) no recanalization. No lethal complications occurred. One patient (1.9%) had pulmonary embolism develop, and two patients (3.8%) had bleeding complications develop. CONCLUSION: With the intraoperative use of hyperthermia-assisted high-dose fibrinolysis, improvement of the results of mechanical thrombectomy of extended DVT was possible. The RHFP protected against systemic side effects of the fibrinolysis and show a high safety of application.

Comparison of laparoscopic aortic clamps in a pulsatile circulation model.

PURPOSE: This study was designed to evaluate the fatigue characteristics and the safety and effectiveness of laparoscopic aortic clamps in a pulsatile circulation model. METHODS: A heart-lung machine was used to create a pulsatile circulation model with bovine aortas resembling the vessels being cross-clamped. Four different models (A-D) of laparoscopic aortic clamps were investigated, and three identical probes of each model underwent testing. Preliminary examinations were conducted to define the size and thickness of the bovine aortas that would allow effective cross-clamping and to detect gross material or functional deficits of the clamps. Then, the instruments were placed in the circulation model, which was set at a frequency of 82/min and a pressure of 200/120 mm Hg. Each clamp was subjected to these conditions for 120 hours and was opened and closed 40 times to stimulate real-life conditions. Clamping failures and mechanical defects were recorded, and the clamp parts were afterward examined with an electron microscope. RESULTS: Two clamp models had to be eliminated from the study after the preliminary examinations. All three probes of model B displayed mechanical defects after a few applications. All probes of model D were excluded because none effectively occluded the aortas. All probes of model A and one probe of model C provided effective cross-clamping during the 120-hour test phase and showed no signs of mechanical failure. Two probes of model C broke after 51 and 57 hours of testing, respectively. Both times, the defect occurred during application of the clamps. The detailed analysis of all instruments after the testing, including electron microscope imaging, revealed that several construction deficits and weak points were responsible for the mechanical failures. CONCLUSION: A surprisingly high incidence of clamping failures and mechanical deficits were encountered during the testing. Of the four clamps tested, only one (model A) seemed to be safe and effective enough for routine clinical use. These disappointing results demonstrate the need for further cooperation between vascular surgeons and instrument manufacturers to develop safe and effective laparoscopic vascular clamps.