Evaluation of sex differences in relative dilatation of thoracic aortic aneurysms.

OBJECTIVES: Treatment recommendations based on thoracic aortic aneurysm (TAA) diameter (D) ignore differences in proportional dilatation between patients of different body habitus and sex. This study's goal is to compare TAA diameters between sexes as a function of relative aortic size as determined by aortic size index (ASI). METHODS: This is a retrospective review of all TAA's treated between 2003 and 2008. ASI was calculated for each patient, which considers aneurysm diameter, patient's height and weight. Values for males and females were plotted separately (TAA diameter vs ASI) and the resulting linear regression equations permitted comparison of proportional dilatation between sexes. RESULTS: In 40 patients (25 males, 15 females) mean TAA diameter did not differ between sexes (6.56 +/- 0.99 vs 7.03 +/- 1.14, P = 0.18), while ASI was larger in females than males (4.21 +/- 0.85 vs 3.24 +/- 0.63, P = 0.0003). Values for ruptured and intact aneurysms did not differ. Linear regression analysis permitted comparison of TAA diameter with ASI between sexes resulting in the following equation: D(Female) = 0.91D(Male) - 0.49. This correlates a 6 cm TAA in a male with a 4.97 cm TAA in a female. CONCLUSIONS: TAA of equal diameter represent a larger proportional dilatation in females compared to males. This could influence repair thresholds that are historically diameter based.

Primary aorto/iliac-enteric fistula-report of 6 new cases.

The management of patients with vascular-enteric fistulas remains a challenging diagnostic and therapeutic problem for the vascular surgeon. Although fortunately quite a rare cause of gastrointestinal bleeding, reported mortality and amputation rates are very high. Fistulas between major vascular structures and the gastrointestinal tract are classified as either primary or secondary. Primary fistulas occur most commonly between an aortic aneurysm and the distal duodenum, while secondary fistulas occur following erosion of prosthetic material into the bowel following aortic reconstruction. The authors report 6 new cases of primary aortoenteric fistula: A malignant aortoenteric fistula in a patient with advanced metastatic squamous cell carcinoma involving the infrarenal aorta and duodenum, 4 cases of primary aortoenteric fistulas in patients with abdominal aortic aneurysms, and 1 iliac-enteric fistula secondary to a common iliac aneurysm. The diagnosis is often difficult to make, and although it was considered in 4 patients preoperatively, the diagnosis was not made until the time of laparotomy in all of these patients. Three patients were treated with an in-situ vascular graft, 2 others had the distal abdominal aorta oversewn and axillobilateral femoral bypass performed, and in the case involving the malignancy, the patient underwent primary aortic repair owing to the extent of the tumor process prohibiting aortic reconstruction. Three patients had primary closure of the intestine performed, and 3 required bowel resection and primary anastomosis. The overall 30-day mortality rate was 50% as 3 patients died in the early postoperative period and the remaining 3 patients survived to be discharged from hospital. One patient (17%) required bilateral above-knee amputations. Treatment of patients with vascular-enteric fistulas is a difficult problem, often associated with delayed diagnosis and high morbidity and mortality rates. Successful surgical management can be achieved with primary closure of the intestinal tract and an in-situ vascular graft or extraanatomic bypass.

Endovascular repair of abdominal aortic aneurysm with coexisting renal allograft: case report and literature review.

The coexistence of an abdominal aortic aneurysm (AAA) and a pelvic renal allograft is a unique clinical situation. Because of the increased susceptibility of the transplant kidney to ischemic injury, various approaches have been developed to minimize allograft ischemia during open aneurysm repair. Endovascular techniques have the potential advantage in this situation of greatly diminishing renal ischemia time. To our knowledge, this approach has not been reported in this situation. We report a case of a 61-year-old male with a 7.0-cm AAA and a functioning right pelvic transplant kidney. There was an adequate aneurysm neck below the level of the superior mesenteric artery with occluded renal arteries. Successful endovascular repair of the aneurysm was achieved using a bifurcated graft and bilateral iliac extensions. Perfusion to the renal allograft was maintained throughout the procedure except for short periods when the graft was expanded with a balloon. Short-term follow-up reveals successful aneurysm exclusion and no deterioration in renal function. This exciting new approach to this challenging clinical problem is reviewed along with other methods of minimizing renal allograft ischemia.

Establishing an endovascular abdominal aortic program--decisions, decisions, decisions: The London Health Sciences Centre experience.

The endovascular repair of abdominal or thoracic aortic aneurysms is an alternative approach to conventional repair in the compromised patient. Although the long-term efficacy of these procedures has yet to be proved, there is growing interest among vascular surgeons and interventional radiologists throughout North America and Europe in the more frequent use of this technique. Starting an endovascular program necessitates extensive cooperation of the interdisciplinary vascular team. Decisions regarding patient selection, equipment, supplies, staff education, and the location of the procedure must be based on sound principles. This article demonstrates how a program can be planned, implemented, and evaluated by the use of a "decision tree." The experience of the London Health Sciences Centre will be used as a benchmark in the discussion of relative merits of branch points in program development. The article gives persons contemplating a program a structured process in decision making to avoid potential pitfalls.

Ischemic tolerance in skeletal muscle: role of nitric oxide.

We tested the hypothesis that ischemic preconditioning (PC) of skeletal muscle provided tolerance to a subsequent ischemic event 24 h later, and that such protection was due to nitric oxide (NO). Male Wistar rats, anesthetized with halothane, were randomly assigned to groups: ischemic (no PC; n = 11), PC (n = 11), PC + N-nitro-L-arginine methyl ester (L-NAME; 100 micromol/l; n = 5), PC + N-nitro-D-arginine methyl ester (100 micromol/l; n= 4), PC + aminoguanidine (AMG; 100 micromol/l; n = 4), ischemic + L-NAME (n= 4), or ischemic + AMG (n = 4). PC consisted of 5x 10 min of ischemia and reperfusion, and, 24 h later, 2 h of ischemia were induced by a tourniquet applied to the limb. With the use of intravital microscopy, the number of perfused capillaries (Npc) in the extensor digitorum longus (EDL) muscle was measured over a 90-min reperfusion period. The ratio of ethidium bromide- to bisbenzimide-labeled nuclei was used to estimate tissue injury. PC preserved Npc (23.6 +/- 2.5) following 2 h of ischemia compared with sham muscles (11.5 +/- 5.1), significantly elevating inducible NO synthase (iNOS) activity (81% increase), but did not afford protection to the parenchyma. L-NAME and AMG prevented ischemia-reperfusion-induced reduction in Npc in muscles without PC. However, after 90 min of reperfusion, L-NAME (Npc = 15.0 +/- 1.7), but not AMG (Npc = 22.8 +/- 3.1), significantly reduced the microvascular protection afforded by PC. We conclude that PC of the EDL muscle resulted, 24 h later, in protection to microvascular perfusion only, and that such protection was due to NO from sources other than iNOS.

The use of arm vein as an alternative conduit for lower-extremity bypass.

A 4-year retrospective review of all cases utilizing arm vein for lower-extremity bypass was undertaken. Thirty-six cases were reviewed. The patients had portions of the basilic or cephalic arm veins, or both, harvested and used as a bypass for limb salvage. Composite grafts using a portion of arm vein were excluded. Information on demographics, risk factors, vascular surgical history, presenting signs and symptoms, surgical complications, patient comfort (arm vs. leg pain), and patency rates was studied. We found that all patients were initially seen with claudication or rest pain, that 22% had gangrenous changes, that there was a male dominance (75%), and that all had previous coronary artery bypass grafts or lower-extremity bypass. Limb salvage rate was 85% at 4 years. Primary patency rate was 71% at 4 years. We conclude that arm vein is a useful and durable conduit for bypass. Patient acceptance and comfort is high.

Intestinal mucosal permeability to 51Cr-ethylenediaminetetraacetic acid is increased after bilateral lower extremity ischemia-reperfusion in the rat.

BACKGROUND: Despite successful revascularization of ischemic extremities, multiorgan dysfunction syndrome develops in some patients. Mechanisms responsible for this are not known; however, the gastrointestinal tract has been implicated as a possible mediator. Our objective was to demonstrate increased intestinal mucosal permeability after bilateral hindlimb ischemia-reperfusion (I-R) in a rodent model. METHODS: Sixteen male Wistar rats were randomized either to 4 hours of bilateral hindlimb tourniquet ischemia and 24 hours of reperfusion (n = 8) or control groups (n = 8). The animals received 10 MuCi 51Cr-ethylenediaminetetraacetic acid (EDTA) by gavage, and excretion was measured in urine collected every 8 hours in 16 animals and every 4 hours in 8 animals. Arterial blood pressure was monitored continuously. Intravenous normal saline solution (3 ml/hr) with fentanyl (2 microgram/100 gm/hr) was continuously administered. Immediately before death complete blood count and levels of arterial lactate, creatinine, and urea were obtained. Mesenteric lymph nodes were harvested from the ileocecal region and cultured. Distal small bowel and proximal colon were preserved for histologic analysis. An additional 11 rats, six experimental and five control, were evaluated for mesenteric lymph node cultures only. RESULTS: Urinary excretion of 51Cr-EDTA was significantly greater in the I-R group between 0 and 8 hours (p < 0.02) and 8 to 16 hours (p < 0.0002) of reperfusion. This increase occurred as early as 4 to 8 hours of reperfusion (p < 0.0001). Urine volume in the I-R group was significantly reduced during 0 to 4 hours of reperfusion (p < 0.002). Hemoglobin and lactate level were significantly different in the I-R group. Leukocyte and platelet counts, levels of creatinine and urea, and colony counts from mesenteric lymph nodes were similar in I-R and control groups. Blinded histologic analysis of bowel segments did not reveal morphologic differences. CONCLUSIONS: Bilateral hindlimb I-R produces remote intestinal mucosal injury shown by significantly increased permeability to 51Cr-EDTA. Such increased mucosal permeability may be important in the development of multiorgan dysfunction syndrome in patients who sustain lower extremity I-R injury.

Leukocyte activity and tissue injury following ischemia-reperfusion in skeletal muscle.

Few studies have correlated the occurrence of leukocytes with the time course of ischemia-reperfusion (I-R)-induced tissue injury in skeletal muscle. The goal of this study was to test the hypothesis that leukocytes were responsible for not only the onset, but progression of parenchymal cell injury within skeletal muscle following no-flow ischemia. Thirteen male Wistar rats (150-250 g) were randomly allocated to either a control (no I-R; n = 3), I-R (n = 5), or a leukopenic I-R group (n = 5). Under halothane anesthesia, the extensor digitorum longus muscle was prepared for intravital microscopy to allow video recording of microvascular perfusion and leukocyte flow behavior following 3 hr no-flow ischemia of the hindlimb. Tissue injury was assessed as the ratio of ethidium bromide (impermeant dye)-labeled nuclei to bisbenzimide (permeant dye)-labeled nuclei (E/B). During reperfusion, the I-R group showed a progressive decline in the number of perfused capillaries (N(C)) (from 19.37 +/- 0.04 to 3.34 +/- 1.18), while leukopenic and control rats were not significantly different. In the I-R group, the number of rolling leukocytes increased from 4.05 +/- 1.93 to 14.77 +/- 1.33 at the onset of reperfusion and remained stable throughout the reperfusion period. The number of stuck leukocytes, in the I-R group, progressively increased from 1.41 +/- 0.01 prior to ischemia to 4.66 +/- 0.01 at the onset of reperfusion to 11.96 +/- 0.01 after 90 min. The index of tissue injury (EIB) increased asymptotically from 0.60 +/- 0.02 to 0.95 +/- 0.01 after 90 min of reperfusion in the I-R group, while leukopenia significantly reduced both the magnitude of tissue injury (i.e., 35% reduction from untreated I-R group) and the onset of such injury. In spite of the benefit afforded by leukopenia, evidence of tissue injury persisted (20% above control baseline level). We conclude that although leukocytes were responsible for the onset of parenchymal injury in skeletal muscle following 3 hr no-flow ischemia they are not the sole mediators of such injury.

Dysphagia lusoria: extrathoracic surgical management.

OBJECTIVE: To report a case of dysphagia lusoria managed by an extrathoracic approach. DESIGN: Case report and literature review. SETTING: A university hospital. PATIENT: A 39-year-old man, who presented with weight loss and dysphagia. Aortography and computed tomography revealed an aberrant subclavian artery compressing the esophagus against the aortic arch. INTERVENTION: The right subclavian artery was divided at its origin and reimplanted onto the right carotid artery. The operation was performed through a right supraclavicular incision without opening the chest. RESULTS: There was no operative morbidity. Six months postoperatively the patient was asymptomatic and had gained weight. There was no radiologic evidence of esophageal compression. CONCLUSIONS: Based on the results of our case of dysphagia lusoria and the reports of others that have started to appear in the literature, consideration should be given to repairing a symptomatic, nonaneurysmal aberrant right subclavian artery through an extrathoracic approach.

Measurement of tissue viability using intravital microscopy and fluorescent nuclear dyes.

Intravital microscopy used with fluorescent vital stains provides the opportunity to measure the temporal and spatial extent of tissue injury following disease processes. However, this assumes that prolonged exposure to such dyes does not alter microvascular perfusion or cellular viability. To test this hypothesis, the extensor digitorum longus (EDL) muscle in 24 male Wistar rats, anesthetized with sodium pentobarbital (Somnotal, 65 mg/kg, ip), were prepared for microscopy. The EDL was either bathed continuously (n = 6) in Krebs solution containing bisbenzimide (5 micrograms/ml; labels nuclei of all cells) and ethidium bromide (5 micrograms/ml; labels nuclei of injured cells) or had dyes topically applied 1 hr (n = 4) and 4 hr (n = 4) following dissection of the muscle. Noxious stimuli (i.e., hypoxia:FiO2 of 8-10% (n = 3), 95% ethanol (n = 3), and 2 hr ischemia followed by 90 min reperfusion (n = 4) were used to test the ability of ethidium bromide, when used in conjunction with intravital microscopy, to differentiate injured tissue. Video recordings at the surface of the EDL muscle were made every 30 min for 5 hr from which the number of perfused capillaries was counted (NCper). The numbers of bisbenzimide- and ethidium bromide-labeled nuclei were counted at the surface of the muscle and at two to three additional locations within the muscle (to a maximum depth of approximately 120-160 microns). The average NCper (19.05 +/- 1.7) remained constant over 5 hr, while the number of nuclei stained by bisbenzimide increased linearly with time from an initial value of 1218 +/- 125.(ABSTRACT TRUNCATED AT 250 WORDS)

Skeletal muscle injury induced by ischemia-reperfusion.

OBJECTIVE: To study the temporal progression of injury in skeletal muscle after ischemia-reperfusion insult by means of intravital videomicroscopy and nuclear fluorescent dyes. DESIGN: A controlled study in an animal model. SETTING: A vascular research laboratory at a university-affiliated hospital. SUBJECTS: Eight male Wistar rats, for each of which the extensor digitorum longus muscle of the hind limb was exposed and prepared. INTERVENTIONS: Two hours of complete no-flow ischemia followed by 90 minutes of reperfusion in five of the rats; the other three rats acted as controls and underwent the same surgical procedure but not ischemia. During the reperfusion period the fluorescent vital dyes bisbenzimide, which permeates all cells, and ethidium bromide, which permeates cells with damaged membranes, were applied. Recordings to videotape were made with the intravital microscope very 15 minutes during the reperfusion period. MAIN OUTCOME MEASURES: The number of perfused capillaries crossing three straight lines on the video monitor were counted as a measure of microvascular dysfunction. An index of tissue injury was calculated as the ratio of the number of nuclei stained by ethidium bromide to the number stained by bisbenzimide (E/B). The number of stuck and rolling leukocytes and the velocity of the rolling leukocytes were determined in postcapillary venules. RESULTS: The mean number of perfused capillaries (and standard error of the mean) fell from 20.71 (1.64)/mm before ischemia to 11.69 (1.18)/mm during reperfusion in the experimental group but remained constant in the control group. In the experimental group E/B progressed from 0.43 (0.05) at the onset of reperfusion to 0.87 (0.03) at the end of reperfusion, the number of rolling leukocytes increased from a preischemia mean of 4.00 (1.90) to 14.80 (1.30)/1000 microns2, and the number of stuck leukocytes increased from 1.42 (0.20) to 9.20 (0.70)/1000 microns2. The velocity of the rolling leukocytes did not differ between the control and the experimental groups. CONCLUSIONS: Although microvascular perfusion decreased quickly to a constant level after 2 hours of noflow ischemia plus reperfusion, a progressive increase in tissue injury occurred, which may correlate with the number of stuck leukocytes.

Intraoperative thrombolytic therapy as a treatment of small vessel thrombosis: an experimental study.

OBJECTIVE: This paper studies the effect of three doses of Streptokinase infused intra-operatively into an animal model of small vessel thrombosis. EXPERIMENTAL DESIGN: This is a controlled trial of intraoperative infusion of thrombolytic agent into a thrombosed arterial segment compared to no infusion into the contralateral limb. EXPERIMENTAL SUBJECTS: 19 New Zealand White rabbits were stratified into 3 groups. INTERVENTIONS: Thrombosis was achieved by infusing a mixture of topical thrombin and autologous blood into individual iliac arteries of the New Zealand white rabbit. A randomly selected hind limb had an infusion of one of three doses of streptokinase (A = 2,500u; B = 5,000u; C = 10,000u) in saline over 20 minute period. Preinfusion and post infusion angiography was performed. MEASUREMENTS: Angiograms were ranked by a radiologist blinded to the side of infusion and clotting parameters were assessed. RESULTS: All limbs at all doses of streptokinase infusion (SK) showed significant clot lysis when compared to the non-infused limb(C). The percentage of improved segments is as follows: iliac: SK = 100%, C = 79%; femoral SK = 79%, C = 32%; tibial SK = 52%, C = 5%. Although there was an elevation in clotting time and a reduction in fibrinogen, levels remained within normal limits. CONCLUSIONS: Streptokinase infused directly into thrombus in arteries even in low doses significantly enhances thrombolysis of vessels which are too small to be cleared by mechanical means. No significant systemic complications were encountered.

Peripheral aneurysms.

Aneurysms of the peripheral arteries usually involve the femoral or popliteal regions. Although not as common as abdominal aortic aneurysms, they carry a significant morbidity if left untreated. Rupture is a rare complication, but embolization or thrombosis may frequently threaten the viability of the limb. Elective repair of peripheral aneurysms will prevent complications of these lesions. This paper outlines the history, diagnosis, and treatment of peripheral aneurysms with emphasis on nursing care.

Myocardial and circulatory performance during the ischemic phase of superior mesenteric artery occlusion.

OBJECTIVE: To investigate myocardial and circulatory parameters during the acute ischemic phase of mesenteric artery occlusion. DESIGN: A prospective, randomized, control trial. SUBJECTS: Twelve, adult, mongrel dogs. INTERVENTIONS: In seven dogs the superior mesenteric artery was occluded with two silk ligatures (experimental group). In five dogs the ligatures were not tied (control group). Measurements were made during 7 hours of occlusion. MAIN OUTCOME MEASURES: Myocardial performance and circulatory performance. RESULTS: There were significant (p < 0.05) reductions in arterial blood pressure, mean pulmonary artery pressure, diastolic pulmonary artery pressure and cardiac index in dogs exposed to intestinal ischemia compared with the control dogs. No differences were identified in ventricular performance, stroke volume index or peripheral vascular resistance index. CONCLUSIONS: Early cardiac and central circulatory changes in massive intestinal ischemia are due to intravascular hypovolemia. Sepsis and myocardial depressant factors were not found to be a cause of death.

Arteritis due to Salmonella with aneurysm formation: two cases.

Although arterial infection due to Salmonella is rare, it remains one of the most common causes of primary mycotic aneurysms. The presentation is one of sepsis, cultures positive for Salmonella and rapid expansion or rupture of the aneurysm. The authors' experience at Victoria Hospital, London, Ont., includes two cases of aneurysms infected with Salmonella--one aneurysm of the aorta and the other of the common femoral artery. Both patients were treated by excision of the aneurysm, extra-anatomic reconstruction in an area remote from the infected field and long-term administration of appropriate antibiotics. One patient was alive and well 36 months after resection. The other died of multiple organ failure 10 days after resection. From a review of the English and French literature since 1948, 64 cases of abdominal aortic aneurysms infected with Salmonella were found; half of the patients survived the perioperative period. The diagnosis of mycotic aneurysm must be considered in any patient with an aneurysm and culture specimens positive for Salmonella. The authors favour wide débridement of the infected aneurysm with extra-anatomic reconstruction. This view is supported by a review of the literature. The appropriate antibiotic therapy is bactericidal rather than bacteriostatic.

The role of descending venography in the management of patients with chronic venous disease of the lower extremity.

The purpose of this paper is to evaluate the efficacy and clinical information obtained from the authors' first 17 consecutive descending venograms. All 17 patients had chronic venous disease refractory to standard conservative and surgical measures. The standard classification of valvular insufficiency was used in evaluating these venograms. There were no deaths, slight morbidity and minimal patient discomfort. In 16 patients meaningful clinical information was derived from the venograms, with 7 patients having deep venous valvular surgery. Descending venography will demonstrate the site of incompetent valves and estimate the degree of reflux. This test is necessary before anticipated reconstruction of deep vein valves.