Recurrent carotid stenosis : results of the asymptomatic carotid atherosclerosis study.

BACKGROUND AND PURPOSE: We sought to determine the incidence of recurrent carotid stenosis in patients in the Asymptomatic Carotid Atherosclerosis Study (ACAS) who had undergone carotid endarterectomy and were prospectively followed with Doppler ultrasound for up to 5 years. METHODS: The ACAS database was interrogated to determine the rate of recurrent carotid stenosis (>/=60%) based up angiogram-validated Doppler data, with a 90% and a 95% positive predictive value, as well as information concerning the technologists' interpretation of percent stenosis. These 3 parameters are reported for each of 3 time intervals: within 3 months of operation (residual disease), between 3 and 18 months (early restenoses), and between 18 and 60 months (late restenosis). RESULTS: Of the 825 patients randomized to the surgical arm of the study, 720 actually underwent carotid endarterectomy, and 645 had complete ultrasound data. The aggregate incidence of residual and recurrent carotid stenosis for all time intervals ranged from 12.7% to 20.4%, depending on the positive predictive value confidence level desired. Residual disease occurred in 4.1% to 6.5%; true, early restenosis was found in 7.6% to 11.4%; and late restenosis occurred in 1.9% to 4.9%. None of the traditional risk factors showed a statistically significant effect on recurrent stenosis. The use of patch angioplasty closure reduced overall risk of restenosis from 21.2% to 7.1%, from 16.7% to 4.6%, and from 27.4% to 8.2%, depending on the PPV confidence level desired (P<0.001). Of the 136 patients judged to have recurrent stenosis, only 8 (5.9%) underwent reoperation (only 1 for symptoms). There was no correlation between late stroke and recurrent stenosis. CONCLUSIONS: Carotid endarterectomy is a durable procedure with a low rate of true restenosis, particularly when patch angioplasty is used to close the arteriotomy.

Inappropriate use of venous duplex scans: an analysis of indications and results.

PURPOSE: The increasing demand for venous duplex scans despite the relative rarity of detecting acute deep venous thrombosis (DVT) prompted us to review our experience with this diagnostic method. METHODS: We retrospectively analyzed the results and indications of 2993 lower extremity venous duplex scans performed between July 1, 1992, and June 30, 1994, at our institution. The indication for the study and the results were prospectively recorded in a computerized data bank. The indications for these studies were leg pain (34%), leg swelling (24%), surveillance for DVT in a patient at high risk (23%), searching for a source of pulmonary embolism (14%), follow-up of previously diagnosed DVT (3%), and other indications (i.e., varicose veins, venous ulcer, 2%). RESULTS: Overall, 74.1% of all scans were completely normal, and only 13.1% detected acute proximal (popliteal vein or higher) DVT. Scans performed for surveillance (87.3% normal) or source of pulmonary embolism (79.6% normal) were significantly more likely to be normal than when performed for any other indication (p < 0.01). When leg edema or calf tenderness was present, the incidence of acute DVT was significantly greater for all indications (p < 0.0001). CONCLUSIONS: The high percentage of normal venous scans implies that this diagnostic method is being inappropriately used. In the current climate of cost containment our data suggest that indications for venous duplex scans must be better defined and that improved education for referring physicians is needed.

Surveillance venous scans for deep venous thrombosis in multiple trauma patients.

The high reported incidence of deep venous thrombosis (DVT) in trauma patients has prompted surveillance venous duplex scanning of the lower extremities. We report our retrospective experience with 183 multiple trauma patients who were admitted to the surgical intensive care unit and underwent 261 surveillance venous scans. There were 122 men and 61 women whose average age was 38 years. All patients were treated prophylactically with either extremity pneumatic compression or subcutaneous heparin to prevent DVT. Most (87%) patients suffered blunt trauma and had either head (3%), spinal (3%), intra-abdominal (9%), or lower extremity (17%) injuries or a combination of injuries (68%). Almost two thirds of the patients had no symptoms suggestive of possible DVT. Of the 261 venous scans performed, 239 (92%) were normal, 16 (6%) were positive for proximal lower extremity DVT, and six (2%) showed thrombus limited to the calf veins. Patients with symptoms of lower extremity DVT were significantly more likely to have proximal DVT compared to those without symptoms (15% vs. 5%, p < 0.05). Patients with spinal injuries also had a higher incidence of proximal DVT (18% vs. 6%, p < 0.05). At current hospital charges, the cost to identify each proximal DVT was $6688. If surveillance duplex scans were performed on all trauma patients in the surgical intensive care unit, the national annual expense would be $300,000,000. Routine DVT surveillance is expensive and should be reserved for symptomatic patients or those with spinal injuries.

Data management in the vascular laboratory.

As the clinical workload in the vascular laboratory increases and as the demand for additional documentation by hospital oversight committees and outside agencies grow, the need for computerized data management will become obvious. Although there are no generic, broadly applicable software programs to automate the laboratory's operations, applications can easily be developed using any of the current database programs to meet the needs of most laboratories. Fortunately, the intense competition in the microcomputer industry has recently made very powerful systems that are capable of providing the necessary computing support increasingly affordable. Such systems can be very simple or incredibly complex depending on the available local expertise and each laboratory's specific needs. In addition to facilitating the laboratory's daily operations, such a system will inevitably expedite the implementation of the laboratory's quality assurance program and will maximize utilization of existing personnel. This type of cost-effective solution to the ever-increasing demand for service will become increasingly important in maintaining the laboratory's fiscal viability. Although the prospects of undertaking such a task might seem daunting, especially to the computer novice, it is important to begin. Keep the system simple, at first, and allow it to develop as local expertise and confidence develop. The only prospect more frightening that sitting down to develop a computerized system for managing the laboratory's data, is the prospect of trying to continue without one!

Preoperative duplex venous mapping: a comparison of positional techniques in patients with and without atherosclerosis.

PURPOSE: Preoperative duplex venous mapping is the preferred modality to measure the diameter of the greater saphenous vein and its suitability as an arterial conduit for infrainguinal bypass. We wanted to determine the optimal mapping technique and maximal venous diameter in patients with and without atherosclerosis. METHODS: Three groups of patients were prospectively studied: younger control subjects (n = 20), preoperative atherosclerotic patients (n = 10), and older control subjects (n = 10). All patients underwent greater saphenous vein duplex mapping in a standardized manner. Maximal internal vein diameters were measured with the subjects in the supine position in bed, in the 20 degree reversed Trendelenburg position, sitting on the edge of the bed, standing, and in the supine position with a high-thigh, low-pressure tourniquet. Measurements were taken just beyond the saphenofemoral junction, in the distal thigh, below the knee, at midcalf, and superior to the medial malleolus. RESULTS: In younger control subjects an increasingly more erect position resulted in progressively larger measured vein diameters at all levels along the length of the leg. Both patients with atherosclerosis and older control subjects had no such increase in venous diameter with any positional change from the supine position to standing. Patients with atherosclerosis also had significantly smaller measured veins than either younger or older control subjects. A high-thigh tourniquet significantly increased vein diameters in the atherosclerotic group to the size of vein diameters in the older control group, although the absolute size differences were not large. CONCLUSIONS: The optimal position for venous mapping is with the patient in a supine position. If the internal vein diameter is below an acceptable minimum size, a high-thigh tourniquet will maximally distend the vein in patients with atherosclerosis. Vein diameter decreases with age and is less distended in patients with atherosclerosis compared with older patients without atherosclerosis.

Spontaneous thrombolysis of native artery occlusions.

Acute arterial ischemia of the lower extremities is a major cause of mortality and limb loss in patients with peripheral vascular disease. Patients with acute limb ischemia secondary to embolus or in situ thrombosis usually require emergency revascularization, either surgically or with the use of thrombolytic agents. It is commonly assumed that heparin therapy alone, without disobliterative intervention, can produce clinical improvement through continued patency and enlargement of the collateral circulation. The occurrence of spontaneous thrombolysis of major limb vessels is not generally accepted. We describe three patients, all with confirmed occlusion of either the iliac or superficial femoral arteries, who had spontaneous thrombolysis of occluded vessels. These experiences document that spontaneous resolution of arterial occlusion does occur, although it may be infrequent.

Intestinal ischemia secondary to thromboangiitis obliterans.

A 38-year-old woman presented with a 10-month history of postprandial abdominal pain and weight loss. She smoked two packs of cigarettes a day, but her history did not indicate diabetes mellitus, hyperlipidemia, or hypercoagulability. A lateral aortogram documented complete occlusion of all three mesenteric arteries but showed no evidence of atherosclerosis, arteritis, or medial fibroplasia. Two retrograde aortomesenteric grafts, one to the superior mesenteric artery and another to the meandering mesenteric artery, utilizing the greater saphenous vein were placed. Pathologic examination of the inferior mesenteric artery demonstrated changes that were considered diagnostic of thromboangiitis obliterans. We found only 10 confirmed cases of thromboangiitis obliterans involving the mesenteric vessels in the English language literature. The present case appears to be the first involving a woman and the only one in which the main trunk of all three mesenteric vessels was involved.

The effect of carbon coating and porosity on early patency of expanded polytetrafluoroethylene grafts: an experimental study.

PURPOSE: Synthetic vascular grafts have never achieved long-term patency comparable to autologous saphenous vein. Changes in graft wall porosity and carbon coating of the luminal surface have both been suggested to improve patency. METHODS: Forty-two mongrel dogs, weighing 20 to 30 kg, underwent bilateral aortoiliac grafting with one of three randomly selected grafts: group I, 60 microns carbon-coated, thin-walled expanded polytetrafluoroethylene (ePTFE); group II, 60 microns thin-walled uncoated ePTFE; or group III, regular ePTFE. All grafts were 10 cm long and had an internal diameter of 5 mm. Twenty-one dogs were killed at 60 days and 21 dogs were killed at 120 days. Thus in each group there were 14 60 microns, thin-walled, carbon-coated ePTFE grafts; 14 60 microns, thin-walled, uncoated ePTFE grafts; and 14 regular ePTFE grafts. RESULTS: At 60 days, 12 (85.7%) of 14 group I, 13 (92.3%) of 14 group II, and 9 (64%) of 14 group III grafts were patent. At 120 days, 12 (85.7%) of 14 group I, 11 (78.6%) of 14 group II, and 6 (42.9%) of 14 group III grafts were patent. The patency of the 60 microns carbon-coated, thin-walled ePTFE at 120 days was significantly improved compared with that of the regular ePTFE (p < or = 0.05). The patency of the 60 microns thin-walled uncoated ePTFE was improved relative to conventional ePTFE at 120 days, although this difference was not statistically significant. There was no significant difference in patency between 60 microns carbon-coated, thin-walled ePTFE and 60 microns thin-walled uncoated ePTFE. When the results were analyzed simply on the basis of graft porosity, the 60 microns porosity grafts had a significantly improved patency compared to the regular ePTFE at 120 days (p < 0.05). Histologically, the 60 microns porosity grafts had significantly better tissue ingrowth along their entire length, regardless of the presence or absence of carbon coating. This ingrowth was present at both 60 days and 120 days. CONCLUSIONS: Our data suggest that increasing ePTFE graft porosity to 60 microns improves overall patency. However, the addition of carbon lining did not appear to further augment patency.

Prevalence of unsuspected abdominal aortic aneurysms in male veterans.

Abdominal aortic aneurysms (AAA) are potentially lethal arterial lesions that are best managed by elective surgical repair. However, asymptomatic AAAs may go undetected on routine physical examination or patients with such lesions may not consult a physician. To determine the prevalence of asymptomatic AAAs in a high-risk population, we retrospectively reviewed all abdominal CT scans on veterans > 50 years of age that had been ordered for indications other than aneurysmal disease during a recent 10-month period. Of the 111 patients studied, 15 (13.5%) had suprarenal and/or infrarenal AAAs (one patient had both). Patients with AAAs were significantly older (p = 0.0001) and were heavier tobacco users (p = 0.003). For patients > 60 years of age with peripheral vascular occlusive disease and a history of tobacco use, there was a 29.2% prevalence for AAA compared with 0% in those without any of these risk factors (p = 0.04). There was a very definite trend suggesting that patients with peripheral vascular disease (p = 0.06) were more likely to have an AAA. Because of the high prevalence of AAAs found in this population we then conducted a prospective study over a 24-month period during which patients > 60 years of age with known peripheral vascular disease and a history of smoking who presented to the vascular laboratory for evaluation of problems not related to AAA were asked to undergo an abdominal CT scan. Fifty-six volunteers agreed to participate in the study. Seven patients had AAAs and one patient had an isolated iliac aneurysm, for a 14.3% overall prevalence of aneurysms.2+ d

Mycotic aneurysm of the tibioperoneal trunk: case report and review of the literature.

Peripheral mycotic aneurysms can occur when septic emboli lodge in either the lumen or the vasa vasorum of a peripheral vessel. Such aneurysms have become rare after the widespread use of aggressive antibiotic treatment for bacterial endocarditis. We report the case of a large mycotic aneurysm of the tibioperoneal trunk 18 months after an episode of Streptococcus viridans bacterial endocarditis. Treatment included complete resection of the aneurysmal sac with restoration of circulation to the posterior tibial artery with a reversed saphenous vein graft. To our knowledge, this is the first case of a mycotic aneurysm of the tibioperoneal trunk reported in the English literature. It also represents the first case in which a mycotic aneurysm of an infrapopliteal vessel was managed successfully with restoration of circulation.

Neurovascular lower extremity complications of the lithotomy position.

The lithotomy position is commonly used during the performance of a variety of abdominal and pelvic operations. Previous publications reporting complications with these operations have been largely anecdotal. We report our experience with eight patients over the past four years who have suffered serious lower extremity complications following operations in which the lithotomy position was used. The average time in the lithotomy position for our patients was 7.4 hours (range: 3.7-12 hours). The mean interval between the original operation and the secondary operation to treat the lower extremity complication was 18.9 hours (range: 2-51 hours). The average hospital length of stay for these patients, 38.4 days (range: 11-119 days), was often prolonged as a direct result of their limb complication. Serious lower extremity complications may result from operations in which the lithotomy position is used. To prevent such complications, strict attention should be paid to the positioning of the limbs in the operating room and the time in the lithotomy position should be minimized. Perioperative monitoring of the lower extremity circulation and compartment pressures are essential in these patients since early detection and treatment of these complications is the only way to prevent permanent limb injury.

Natural history of claudicants with critical hemodynamic indices.

We reviewed the records of approximately 1,500 patients seen in the Vascular Laboratory of the Cincinnati Veterans Affairs Medical Center from 1980 to 1987 and identified 23 patients (25 limbs) who met all of the following criteria: 1) an ankle/brachial index less than or equal to 0.35; 2) an ankle or transmetatarsal pulse volume recording less than or equal to 3 mm in amplitude; and 3) no history of ischemic rest pain or gangrene. These patients were followed in the Vascular Laboratory for periods ranging from 11 to 127 months (mean 45.2 months). The study was terminated in March 1991 or when revascularization or amputation was required for limb-threatening symptoms or if the patient expired. Thirteen extremities (52%) showed no progression to limb-threatening symptoms. Claudication actually improved in three, remained unchanged in eight, and progressed in two. Twelve (48%) extremities developed limb-threatening conditions, with rest pain occurring in three, ischemic ulceration in six and gangrene in three. Eight of these limbs underwent revascularization and only one ultimately required major amputation. Another extremity presented with extensive gangrene and underwent a primary above-knee amputation. Three other patients did not undergo revascularization because of death in one and refusal in two others. Patients with intermittent claudication who have critical hemodynamic indices are at much greater risk for developing symptomatic limb-threatening ischemia. Close follow-up is mandatory since nearly half of these patients will eventually require operation for limb salvage. Patients who are unlikely to comply with a regular follow-up program may be considered for early revascularization to prevent complications of limb-threatening ischemia.

Temporary closure of the abdominal wall by use of silicone rubber sheets after operative repair of ruptured abdominal aortic aneurysms.

Management of patients after operative repair of abdominal aortic aneurysms can be further complicated if primary closure of the abdominal wall cannot be technically accomplished or is associated with profound increases in intraabdominal and peak inspiratory pressures. We recently treated five patients with ruptured abdominal aortic aneurysms and one patient with a ruptured thoracoabdominal aneurysm whose abdominal incisions had to be closed with a Dacron reinforced, silicone sheet. All patients were hemodynamically unstable either at admission to the hospital or became so during operation. Four patients required the insertion of a silicone rubber sheet at the primary operation because of massive retroperitoneal hematoma or edema of the bowel wall or both. Incisions in two patients were closed primarily, but the patients required reexploration and secondary closure with silicone rubber sheets because of the development of marked increases in peak inspiratory pressures, intraabdominal pressures, and decreased urinary output. Four of the six patients subsequently underwent successful removal of the silicone rubber sheets with delayed primary closure of the abdominal wall, and two others died before removal. The patient with the ruptured thoracoabdominal aneurysm died on postoperative day 20 because of pulmonary sepsis but had a healed abdominal incision. The three surviving patients have been discharged. A silicone rubber sheet may be necessary for closure of the abdominal wall after repair of ruptured abdominal aortic aneurysm in patients where primary abdominal wall closure is impossible or where it results in compromise in respiratory or renal function.

Complications of anomalous origin of the right subclavian artery: case report and review of the literature.

A 35-year-old black woman presented with thrombosis of an anomalous right subclavian artery and distal arterial embolization. Initially, her right subclavian artery was reimplanted onto the common carotid artery, and a brachial artery embolectomy plus intraoperative thrombolytic therapy were used to reopen her distal arterial circulation. When her brachial artery repair thrombosed the following day, a distal ulnar artery bypass and repeat thrombolytic therapy were required to restore arterial patency. Six months later, she returned with severe, progressive, neointimal hyperplasia of her brachial artery and a second attempt at arterial reconstruction was unsuccessful. She eventually required a right below-elbow amputation. This patient demonstrated an anomalous right subclavian artery that presented with distal embolization without an antecedent history of severe atherosclerotic disease or the development of a right subclavian artery aneurysm. A review of the medical literature relating to complications of this anomaly is provided.