Polytetrafluoroethylene and bovine mesenterial vein grafts for hemodialysis access: a comparative study.

PURPOSE: This study aimed to evaluate the safety and patency rate of bovine mesenterial vein grafts (BMVG) for vascular access (VA) in hemodialysis patients (HDP), compared to expanded polytetrafluorethylene (ePTFE grafts) over a mid- to long-term period. METHODS: Patency and complication rate of 23 consecutive HDP with BMVG for VA were compared to a control group consisting of 23 similar HDP with ePTFE grafts. In both groups, the graft was placed preferably in a forearm loop configuration. The same surgeon performed all procedures. All patients were followed over a period of 4 yrs. RESULTS: Graft placement was successful in all patients. Patency rates did not differ significantly in both groups. However, there were less severe complications in the BMVG group. CONCLUSION: The BMVG is a viable alternative for HD access in patients where autologous construction is not possible, and should be given priority in patients with a failed ePTFE graft or high risk for infection.

Influence of naloxone on gastric emptying of solid meals, myoelectrical gastric activity and blood hormone levels in young healthy volunteers.

There is considerable evidence that opioid mechanisms are involved in the mediation of pyloric motor responses that in turn regulate gastric emptying. The purpose of this randomized, placebo-controlled crossover study was to investigate the effect of naloxone on gastric emptying of a solid meal, gastric myoelectrical activity and the postprandial release of gastrointestinal peptides and neuropeptides in 20 healthy volunteers. Naloxone was administered as an intravenous bolus, followed by continuous infusion according to an intravenous dosing nomogram. Gastric emptying time was evaluated by scintigraphy and gastric myoelectrical activity was evaluated by cutaneous electrogastrography. Naloxone did not significantly alter gastric half-emptying time and postprandial dominant gastric electrical frequency compared with placebo. It also did not significantly change the plasma levels of several peptide hormones with the exception of neuropeptide Y, which was significantly increased (P = 0.001). In conclusion, in doses that influence human intestinal motility, naloxone had no effect on gastric motility and release of several peptide hormones in healthy male volunteers. The importance of the isolated increased neuropeptide Y plasma level needs further investigation.

Risk assessment in patients with ruptured abdominal aortic aneurysms.

OBJECTIVES: Surgery of ruptured abdominal aortic aneurysms is associated with a high mortality rate, mostly related to multi-organ-failure after a prolonged intensive care therapy. In a retrospective study attempts are made to identify individual organ-dysfunction risk profiles influencing the outcome. METHODS: Fifty seven patients (53 men, 4 women, mean age 71.8 +/- 8.8 years) with ruptured abdominal aortic aneurysms underwent graft replacement in a three year period. Fourty eight preoperative, 13 intraoperative and 34 postoperative variables were analyzed. A multi-organ dysfunction (MOD) score was used. RESULTS: The perioperative mortality rate was 31%. Significance of pre-existing risk factors at admission was identified only for cardiovascular diseases. Multiple linear regression analysis indicated that hemoglobin < 90 g/l, systolic blood pressure < 80 mmHg and ECG signs of ischemia at admission are highly significant risk factors. Patients, who died later than 48 hours postoperatively, deceased mainly from MOD (93%) and required intensive care significantly longer than surviving patients (p < 0.0005). All patients with a MOD score > or = 4 died (n = 7). These patients required 26% of all ICU-days and 72% of the ICU-days of the nonsurvivors. CONCLUSION: Patients with ruptured aortic aneurysms should not be excluded from treatment. However, a physiological scoring system after 48 h appears justifiable in order to decide on the appropriateness of continued ICU support.

[Incidence, classification and therapy of isolated pelvic artery aneurysm]. / Häufigkeit, Klassifikation und Therapie der isolierten Beckenarterienaneurysmen.

INTRODUCTION: Isolated iliac artery aneurysms (IAA) are rare. The rupture risk, however, is high and the diagnosis can be difficult. The aim of this study was to report the frequency, morphology and outcome of these lesions. METHODS: Retrospective analysis of the medical data of all patients treated for IAA from 1990 to 1999. RESULTS: Fifty-nine consecutive patients, 55 (93%) male and 4 (7%) female, were included in the study. The median age was 68 (48-86) years. During the same time period, 741 consecutive patients with aortoiliac aneurysms were treated; thus the frequency of IAA was 8%. The median diameter of the IAA was 7 (3-12) cm. Most patients had at least one risk factor. IAA were unilateral in 40 (68%) or bilateral in 19 (32%) patients and affected the common iliac artery in 25 (19%), the internal iliac artery in 11 (19%) and simultaneously the common and internal iliac artery in 21 (36%) patients. Additional involvement of the external iliac artery was noted in 2 (3%) patients. Thirty-six (61%) patients with IAA underwent elective treatment while 23 (39%) patients had to be treated on an emergency basis. Endovascular stent grafts were inserted in 2 patients. Overall mortality was 10% (n = 6), 2.8% (n = 1) in asymptomatic and 22% (n = 5) in symptomatic or ruptured IAA. Overall morbidity in this study was 30%. The median follow-up of the patients was 36 (2-120) months. DISCUSSION: Surgical therapy in patients with asymptomatic IAA can be performed with a reasonable mortality. However, mortality and morbidity in patients with symptomatic or ruptured IAA remains high. Postoperative long-term results are excellent. The value of endovascular therapy for IAA has yet to be determined.

[Results of surgical therapy and classification of non-ruptured abdominal aortic aneurysms]. / Standortbestimmung der chirurgischen Therapie und Klassifikation nicht rupturierter Bauchaortenaneurysmen.

INTRODUCTION: Surgery for symptomatic aortic abdominal aneurysms (sAAA) is associated with an increased mortality and morbidity compared to asymptomatic aortic aneurysms (aAAA). With the advent of endovascular therapy, an alternative therapeutic modality has become available. Endovascular therapy, however, depends on certain morphologic criteria, whereas open surgery can be performed on any type of AAA. The purpose of this study was to analyse our data of surgical treatment of non ruptured AAA and to identify the amount of patients in whom endovascular therapy would have been possible. METHODS: Retrospective analysis of the medical data of all patients operated upon non ruptured AAA in our department by 3 responsible vascular surgeons from 1995-1999. RESULTS: 225 consecutive patients with a median age of 65 (42-95) years were included in the study. There were 184 (82%) male and 41 (18%) female patients with 143 (63.5%) aAAA and 82 (36.5%) sAAA. Patients with sAAA underwent emergency aneurysm repair and had a significantly increased aneurysm diameter compared to the aAAA, who underwent elective surgical aneurysm repair (6.9 +/- 1.6 cm vs. 6 +/- 1.2 cm; p = 0.002). A total of 11 (4.9%) patients had an inflammatory AAA. Smoking was found to be the only significant increased preoperative risk factor in the group of sAAA compared to aAAA (91 vs. 35 patients; p = 0.008). Morbidity was significantly increased in the patients with sAAA compared to the aAAA (55% vs. 31.5%; p = 0.041) The mortality however did not differ significantly in the two groups (2 vs. 3 patients; p = 0.691). Considering morphological criteria of the AAA, endovascular therapy would have been possible in 59 (26%) patients. However, in 24 (11%) of the 59 patients, endovascular therapy was not feasible because of aortic kinking, heavy calcification of the aneurysm neck, a patent inferior mesenteric artery or atherosclerotic diseased iliac arteries. Consequently, only 35 (15%) patients would have qualified for an endovascular therapy. DISCUSSION: Surgical therapy can be performed in patients with asymptomatic and symptomatic AAA with an equal low mortality. This finding underlines the fact, that surgical therapy still remains the standard therapy for AAA. In addition, in our study only a relative small amount of patients would have qualified for an endovascular therapy.

Ischaemia/reperfusion contributes to colonic injury following experimental aortic surgery.

OBJECTIVES: ischaemia of the colon is an important complication of abdominal aortic aneurysm (AAA) repair. The aim of this animal study was to investigate the effect of sequential ischaemia and reperfusion on sigmoid mucosal pO2 and its association with local ET-1 release. MATERIAL AND METHODS: twelve pigs underwent colonic ischaemia followed by complete reperfusion. Six other animals were sham controls. A Clark-type microcatheter was used for continuous mucosal pO2 measurements. Serial systemic and inferior mesenteric vein blood samples were obtained for determination of ET-1 concentration. Neutrophil extravasation was assessed by tissue myeloperoxidase (MPO) activity. RESULTS: arterial occlusion was associated with a gradual decrease of mucosal pO2 and local release of ET-1. After restoration of blood flow, mucosal pO2 returned to near baseline values, whereas ET-1 reached its maximum concentration during the reperfusion period. MPO activity was significantly increased. CONCLUSIONS: colonic ischaemia and reperfusion causes neutrophil extravasation and local ET-1.

[Assessment of intraoperative duplex sonography during carotid endarterectomy]. / Wertigkeit der intraoperativen Duplexsonographie bei der Carotisendarterektomie.

INTRODUCTION: Carotid endarterectomy (CEA) for prevention of strokes mandates a high amount of experience and a meticulous surgical technique. Intraoperative morphologic as well as hemodynamic monitoring of the endarterectomized arteries is rarely performed. The purpose of this study was to determine the value of intraoperative colour-coded-duplex-sonography to recognize eventual intraoperative technical problems that might result in serious cerebral damage. METHODS: Prospective analysis of the medical data of all patients who underwent CEA for treatment of high-grade carotid stenosis between 1996 and 1999. Adequacy of the repair was assessed intraoperatively by duplexsonography. RESULTS: Of 142 consecutive patients with a median age of 68 (43-84) years, 104 (73 %) were men and 38 (27 %) were women. 9 patients (6 %) had bilateral CEAs. Intraoperative duplexsonography revealed abnormalities during 11 (7 %) of 151 CEAs. 4 (3 %) were considered major and underwent immediate revision. There was one (0.7 %) temporary neurologic deficit (hyperperfusion syndrome) and 2 (1.3 %) cases of fatal intracerebral hemorrhage. 6 (4 %) postoperative surgical complications occurred, i. e. 3 cases of major wound hematoma (with revision) and 3 cases of temporary cranial nerve palsy. Median length of follow-up was 11 (3-35) months. No late neurologic event occurred during follow-up. 5 (3 %) patients developed asymptomatic restenosis. DISCUSSION: Routine intraoperative duplexsonography is a valuable and reliable diagnostic tool to detect correctable technical problems during CEA that subsequently may lead to neurological deficits, fatal stroke or a high incidence of restenosis.

[Rare, but severe complication of varicose vein surgery. Compartment syndrome]. / Seltene, aber folgenschwere Komplikation der Varizenchirurgie. Das Kompartment-Syndrom.

The compartment syndrome is an extremely rare complication after varicose vein surgery. If the early symptoms are not recognized and a treatment is not performed immediately most patients lose sensomotory function. Three cases with compartment syndrome after varicose vein stripping were the reason to point out the anatomy and pathophysiology of this complication and to explain the surgical technique.

Treatment of ruptured abdominal aortic aneurysm, a permanent challenge or a waste of resources? Prediction of outcome using a multi-organ-dysfunction score.

OBJECTIVES: in a retrospective study, attempts have been made to identify individual organ-dysfunction risk profiles influencing the outcome after surgery for ruptured abdominal aortic aneurysms. METHODS: out of 235 patients undergoing graft replacement for abdominal aortic aneurysms, 57 (53 men, four women, mean age 72 years [s.d. 8.8]) were treated for ruptured aneurysms in a 3-year period. Forty-eight preoperative, 13 intraoperative and 34 postoperative variables were evaluated statistically. A simple multi-organ dysfunction (MOD) score was adopted. RESULTS: the perioperative mortality was 32%. Three patients died intraoperatively, four within 48 h and 11 died later. A significant influence for pre-existing risk factors was identified only for cardiovascular diseases. Multiple linear-regression analysis indicated that a haemoglobin <90 g/l, systolic blood pressure <80 mmHg and ECG signs of ischaemia at admission were highly significant risk factors. The cause of death for patients, who died more than 48 h postoperatively, was mainly MOD. All patients with a MOD score >/=4 died (n=7). These patients required 27% of the intensive-care unit (ICU) days of all patients and 72% of the ICU days of the non-survivors. CONCLUSION: patients with ruptured aortic aneurysms from treatment should not be excluded. However, a physiological scoring system after 48 h appears justifiable in order to decide on the appropriateness of continual ICU support.

Endoscopic measurement of pancreatic tissue perfusion in patients with chronic pancreatitis and control patients.

BACKGROUND: Pancreatic blood flow is diminished in experimental models of acute and chronic pancreatitis. We attempted to develop a safe and reliable technique for its measurement in patients and to examine blood flow in patients with chronic pancreatitis and in control subjects. METHOD: Pancreatic blood flow was measured using the hydrogen gas clearance technique and an endoscopically placed platinum ductal electrode. Pancreatic blood flow was measured in 12 patients with chronic pancreatitis diagnosed clinically and radiographically, and in 11 control patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) for non-pancreatic pathology. RESULTS: Patients with chronic pancreatitis had a significantly lower pancreatic blood flow compared with control patients (51.5 versus 91.7 mL/min/100 gm, p < 0.01). With secretin stimulation pancreatic blood flow increased in two control patients, whereas this notable rise was not seen in three patients with chronic pancreatitis. CONCLUSIONS: Measurement of pancreatic blood flow with an endoscopically placed electrode is relatively safe and simple to perform. The scarring and vascular fibrosis associated histologically with chronic pancreatitis is reflected in lower pancreatic blood flow.

Surgery for aortoiliac aneurysms in kidney transplant recipients.

With the increase of long-term survivors following renal transplantation, aorto-iliac aneurysms requiring surgical management may be encountered more often. Our experience with temporary shunts for renal transplant protection during aorto-iliac aneurysm repair is presented along with a literature review of all cases on the subject. Three male patients with a median age of 56 (range 50-61) years were operated on for a dissecting aneurysm of the common iliac artery in one, respectively abdominal aortic aneurysm in the two remaining patients. All patients had impaired transplant function preoperatively with a median serum creatinine level of 167 (range 134-202) micromol/L and a median blood urea nitrogen concentration of 15 (range 9-23) pmol/L. The intra- and postoperative course was uneventful in all patients. Median postoperative serum creatinine level and blood urea nitrogen concentration were 135 (range 123-151) micromol/L and 10 (range 9-11) pmol/L, respectively. Aorto-iliac surgery in renal transplant recipients can be performed without transplant protection. However, in patients with a deteriorated transplant function or if a prolonged aortic cross-clamp time is anticipated, renal allograft protection measures may be beneficial to prevent possible ischemic damage.

Mural aortic thrombi: An important cause of peripheral embolization.

PURPOSE: Arterial thromboembolism in patients with an unknown source of embolization is still associated with significant morbidity and mortality. The advent of transesophageal echocardiography (TEE) and magnetic resonance imaging (MRI) and the more frequent use of computed tomography (CT) have led to the identification of mural aortic thrombi (MAT) as a source of distal embolization in a much higher proportion of patients than previously appreciated. The incidence, diagnosis, and treatment of patients with MAT is reported. METHODS: In a prospective study, from January 1996 to December 1998, 89 patients with acute embolic events underwent an extensive diagnostic workup, consisting of TEE, CT, or MRI, to detect the source of embolization. Patients in whom the heart (n = 51), occlusive aortoiliac disease (n = 16), or aortic aneurysms (n = 12) was identified as the source of embolization were excluded. RESULTS: Five female and three male patients, with a median age of 63 years (range, 35 to 76 years), with bilateral or repetitive embolic events resulting from MAT were identified, representing 9% of all patients with arterial thrombembolism. All patients had several risk factors for atherosclerosis, but only one young patient had a single risk factor that promoted thrombosis. Successful percutaneous catheter aspiration embolectomy was performed in six patients. The remaining two patients underwent surgical thromboembolectomy. A below-knee amputation had to be performed in two patients, thus representing a morbidity of the primary treatment of 25%. MAT of equal value were detected in the ascending (n = 1) and thoracic aorta (n = 3) by means of TEE, CT, or MRI. MAT in the abdominal aorta (n = 4) were identified by means of CT and MRI. Surgical removal of MAT was performed in seven patients by means of graft replacement of the ascending aorta (n = 1), open thrombectomy of the descending aorta (n = 2), and thrombendarterectomy of the abdominal aorta (n = 4), without intraoperative or postoperative complications. No recurrence of MAT occurred during a median follow-up period of 13 months (range, 4 to 24 months). CONCLUSION: MAT represent an important source of arterial thrombembolism. A diagnostic workup of the aorta, preferably by means of CT or MRI, should be performed in all patients in whom other sources of embolization have been ruled out. The ideal therapeutic approach to these patients still awaits prospective evaluation. However, based on our experience, MAT can be successfully treated with a definitive surgical procedure in selected patients, with low mortality and morbidity.

Effect of pancreaticojejunostomy on fibrosis, pancreatic blood flow, and interstitial pH in chronic pancreatitis: a feline model.

OBJECTIVE: To study the relation between fibrosis, pancreatic blood flow (PMBF), interstitial pH (pHi), and the effects of pancreaticojejunostomy (PJ) in chronic pancreatitis. BACKGROUND: Chronic pancreatitis is associated with low PMBF and pHi, suggesting the existence of underlying ischemia. METHODS: In cats, the main pancreatic duct was partially obstructed and the animals were studied 2, 4, 6, and 8 weeks later. PJ was performed after 2 and 4 weeks of ductal obstruction and studied 4 weeks later. PMBF and pH were measured before and after stimulation with secretin and cholecystokinin. pHi was measured with microelectrodes, PMBF by hydrogen gas clearance. Histologic analysis of the pancreas with Sirius red (collagen stain) and fast green FCF (noncollagen protein) stains allowed semiquantitative analysis of the ratio between collagen and total protein (C/TP). RESULTS: With the evolution of chronic pancreatitis, there is a progressive increase in the collagen content and C/TP ratio, a reduction in basal PMBF and pHi, and loss of the normal response to stimulation. Early PJ restores collagen content, C/TP ratio, and basal and stimulated PMBF and pHi to normal. PJ performed in established CP returns the C/TP ratio to normal, improves basal PMBF, and restores the normal hyperemic response to secretion. Basal pHi is improved and the "acid tide" associated with secretin returns, but there is still no response to cholecystokinin. CONCLUSIONS: Pancreaticojejunostomy restores the elevated collagen and C/TP ratio to normal and reverses the ischemia present in CP. The authors speculate that restoration of PMBF and its normal response to stimulation allows "regeneration" and restoration of secretory function.

[Cryopreserved arterial homografts. A treatment alternative for infected vascular reconstructions]. / Kryopräservierte arterielle Homografts. Therapeutische Alternative bei tiefer Gefässinfektion.

Deep wound infection or prosthetic vascular graft infection is one of the most challenging complications in vascular surgery with a substantial early and late morbidity and mortality. Surgical treatment usually consists of complete removal of infected vessels or prosthetic vascular grafts followed by extraanatomic bypass procedures. However, this method is associated with significant mortality and amputation rates. Herein, we report two patients with deep wound and prosthetic vascular graft infection who underwent successful in situ reconstruction with cryopreserved arterial homografts. Although the long-term results are missing, this approach may offer a possible treatment alternative for this potentially life-threatening complication.

Microcirculation in chronic alcoholic pancreatitis: a laser Doppler flow study.

Experimental chronic pancreatitis is associated with microcirculatory disturbances but can also be induced or aggravated by perfusion changes. Microcirculatory alterations in human chronic pancreatitis are poorly defined. In this clinical study we investigated pancreatic microcirculation in the normal human pancreas and in chronic pancreatitis by laser Doppler flowmetry. Laparotomy was performed on 13 patients with nonpancreatic disease and on nine patients with chronic alcoholic pancreatitis for pancreatic head resection. Blood flow was measured over the pancreatic head, the uncinate process, over the mesenteric vein, the pancreatic corpus, and over the pancreatic tail by laser Doppler flowmetry. Blood flow was highest in the head of a normal pancreas with a mean of 436 +/- 34 perfusion units (PU), 399 +/- 43 PU in the uncinate process, 286 +/- 30 PU in the pancreatic corpus, and 351 +/- 46 PU in the tail of the pancreas. In the normal pancreas, lowest blood flow was measured over the mesenteric vein (228 +/- 23 PU). In chronic pancreatitis, blood flow in the pancreas was significantly decreased across the whole pancreas (p < 0.01). Furthermore flow-wave pattern was altered in chronic pancreatitis as compared with the normal pancreas. The normal human pancreas has a spatial variation in blood flow, correlating with the pancreatic arterial blood supply. In the chronically inflamed human pancreas, blood flow is significantly diminished, with a lower flow toward the pancreatic head.