Intravenous intravascular ultrasound for arterial visualization: a feasibility study

PURPOSE

The advent of endovascular grafting has created detailed imaging requirements for which intravascular ultrasound (IVUS) may be useful. Since intra-arterial IVUS imaging uses space within endovascular graft delivery systems and risks embolism, we investigated the use of intravenous IVUS imaging of arterial vasculature and endovascular grafts, a technique that appears not to have been previously described.

METHODS

IVUS catheters with 12.5- and 20-MHz transducers were inserted through the common femoral artery and vein of mature sheep. Transcutaneous images were also obtained with a 5-MHz linear transducer. B-mode images of the aortoiliac arterial segments and diameter measurements were recorded from both access vessels using anatomic landmarks for site localization. To assess device visualization from the intravenous image source, studies were done in vessels containing previously placed endovascular stent-grafts.

RESULTS

In this feasibility study, comparison among intravenous IVUS, arterial IVUS, and external ultrasound indicated equal diameter precision and ability to recognize arterial structures. Comparison of arterial diameter, whether obtained from an arterial, venous, or transcutaneous source, showed similar values.

CONCLUSIONS

We conclude that it is probable for such techniques to be usefully applied to human aortoiliac arterial segments and that further investigation of arterial visualization from adjacent venous structures is warranted.

Gender bias in use of venous ultrasonography for diagnosis of deep venous thrombosis

PURPOSE

We observed that ultrasound examinations for deep venous thrombosis (DVT) were more frequently requested for women than for men in our vascular laboratory serving a general outpatient population and referral 774-bed hospital. Because existing literature presents conflicting information about sex differences in occurrence of DVT, we investigated correlation in our population with positive ultrasound study results and risk factors for DVT.

METHODS

In 13 months, 2055 ultrasound examinations for DVT were requested. Of these, 300 patients (15%) were categorized in four subgroups: 75 ultrasonography-negative men, 75 ultrasonography-negative women, 75 ultrasonography (DVT)-positive men, and 75 ultrasonography (DVT)-positive women for risk factor analysis.

RESULTS

Women comprised 64% (1311 of 2055) and men 36% (744 of 2055) of ultrasound examinations requested, but men had significantly higher incidence of DVT-positive ultrasonography results (101 of 744 [14%]) compared with women (118 of 1311 [9%]) (p = 0.002 by chi-square testing). There were no significant sex differences in conventional DVT risk factors and no difference in aggregate number of risk factors. The anatomic distribution of DVT was the same in men as in women. Among those having negative ultrasonography results, significantly more outpatient examinations were performed in women (p = 0.018 by t testing).

CONCLUSIONS

Gender bias exists in use of ultrasonography for diagnosis of DVT. The greater incidence of women undergoing venous ultrasonography is not explained by higher prevalence of DVT risk factors or of higher occurrence of positive ultrasound examination results. Further investigation is needed to determine whether these differences indicate underuse of ultrasonography in men or overuse in women.

Preoperative assessment of alternative veins

Duplex ultrasonography, with or without color flow, has replaced phlebography as the technique of choice to select veins for autogenous bypass grafts. Although anatomic location and length are well-defined by ultrasound, evaluation of the venous wall itself is still imperfect. In situ diameters are less than those of arterialized veins. Ultrasonic search is most valuable in the examination of patients with good veins obscured by a layer of fat. Preoperative knowledge of variant anatomy and location of major veins and their branches facilitates bypass surgery. The preoperative vein mapping should be available in the operating room to guide the placement of incisions for unroofing and exploration directly over veins and vein segments that have a high likelihood of being usable. The finding of a useful vein when none is apparent on physical examination may enable the construction of an autogenous bypass in lieu of a less desirable prosthetic graft or leg amputation.

Inhibition of aortic aneurysm development in blotchy mice by beta adrenergic blockade independent of altered lysyl oxidase activity

PURPOSE

This study was designed to define the effects of beta-adrenergic blockade on aortic lysyl oxidase (LO), an enzyme responsible for elastin and collagen cross-linking, and aneurysm formation in the blotchy mouse. It was hypothesized that beta-blockade would inhibit the development of aneurysms because of its hemodynamic effect rather than a direct effect on LO activity.

METHODS

Three groups of mice were studied: group I--normal littermates of blotchy mice; group II--untreated blotchy mice; group III--blotchy mice given either propranolol, atenolol, or nadolol. Data from the three different beta blocker-treated animals, group III, were statistically identical and were combined for analysis. The study was concluded when the mice were 4 months of age. At that time systolic blood pressure, heart rate, and aortic diameters were measured, and the entire aorta from each mouse was subjected to a bioassay for LO activity.

RESULTS

Group I normal mice had an aortic arch diameter of 0.10 +/- 0.02 cm. Group II blotchy mice developed aortic arch aneurysms with a diameter of 0.21 +/- 0.03 cm. In Group III, beta blockade reduced the aortic arch diameter in blotchy mice to 0.11 +/- 0.03 cm. Mean heart rate in group III beta-blocked mice was reduced 25% compared with group I normal mice, and 18% compared with group II untreated blotchy mice. Blood pressures were similar in all three groups. Group II blotchy mice exhibited approximately half of the aortic LO activity (2.43 +/- 0.57 cpm/micrograms protein) noted in group I normal mice (5.82 +/- 1.06 cpm/micrograms protein). Aortic LO activity in group III blotchy mice remained low (2.09 +/- 0.85 cpm/micrograms protein) despite administration of beta-blockers.

CONCLUSIONS

This is the first study to document an actual decrease in the level of aortic LO activity in blotchy mouse. beta-Blockade inhibits development of aortic aneurysms in blotchy mice. This is associated with a reduction in heart rate, but not by alterations in LO activity.

Aortic aneurysm morphology for planning endovascular aortic grafts: limitations of conventional imaging methods

PURPOSE

To test whether conventional computed tomography scanning (CT) and contrast aortography (CA) provide adequate data for planning endovascular aortic grafting by measuring 33 parameters in patients having both imaging examinations for evaluation of abdominal aortic aneurysms (AAA).

METHODS

Fifty consecutive patients with AAA (41 men, 9 women; average age 65 years) had CT and CA (mean 26 days between exams). The data collected and analyzed included: 8 sites of diameter, 4 lengths, 6 angles, and 15 other dimensional measurements.

RESULTS

Conflicts between CA and CT data were common. Eighteen patients appeared to have a distal cuff by CA but not by CT. Proximal neck length could not be assessed by CT in 5 and had a difference between CA and CT > 1 cm in 25 patients. CA overestimated neck length in 11 patients. Common iliac artery angulation > 60 degrees unilaterally in 27 patients and bilaterally in 5. Seven patients had both iliac aneurysm and > 60 degree iliac angulation. Thirteen patients had one or more iliac aneurysms (> 2 cm) shown by CT but not by CA.

CONCLUSIONS

For endovascular graft planning: (1) more detailed measurement is required than for traditional surgery; and (2) conventional CT and CA are complementary imaging studies, but each has important limitations.

Guidelines for carotid endarterectomy. A multidisciplinary consensus statement from the Ad Hoc Committee, American Heart Association

BACKGROUND AND PURPOSE

Indications for carotid endarterectomy have engendered considerable debate among experts and have resulted in publication of retrospective reviews, natural history studies, audits of community practice, position papers, expert opinion statements, and finally prospective randomized trials. The American Heart Association assembled a group of experts in a multidisciplinary consensus conference to develop this statement.

METHODS

A conference was held July 16-18, 1993, in Park City, Utah, that included recognized experts in neurology, neurosurgery, vascular surgery, and healthcare planning. A program of critical topics was developed, and each expert presented a talk and provided the chairman with a summary statement. From these summary statements a document was developed and edited onsite to achieve consensus before final revision.

RESULTS

The first section of this document reviews the natural history, methods of patient evaluation, options for medical management, results of surgical management, data from position statements, and results to date of prospective randomized trials for symptomatic and asymptomatic patients with carotid artery disease. The second section divides 96 potential indications for carotid endarterectomy, based on surgical risk, into four categories: (1) Proven: This is the strongest indication for carotid endarterectomy; data are supported by results of prospective contemporary randomized trials. (2) Acceptable but not proven: a good indication for operation; supported by promising but not scientifically certain data. (3) Uncertain: Data are insufficient to define the risk/benefit ratio. (4) Proven inappropriate: Current data are adequate to show that the risk of surgery outweighs any benefit.

CONCLUSIONS

Indications for carotid endarterectomy in symptomatic good-risk patients with a surgeon whose surgical morbidity and mortality rate is less than 6% are as follows. (1) Proven: one or more TIAs in the past 6 months and carotid stenosis > or = 70% or mild stroke within 6 months and a carotid stenosis > or = 70%; (2) acceptable but not proven: TIAs within the past 6 months and a stenosis 50% to 69%, progressive stroke and a stenosis > or = 70%, mild or moderate stroke in the past 6 months and a stenosis 50% to 69%, or carotid endarterectomy ipsilateral to TIAs and a stenosis > or = 70% combined with required coronary artery bypass grafting; (3) uncertain: TIAs with a stenosis < 50%, mild stroke and stenosis < 50%, TIAs with a stenosis < 70% combined with coronary artery bypass grafting, or symptomatic, acute carotid thrombosis; (4) proven inappropriate: moderate stroke with stenosis < 50%, not on aspirin; single TIA, < 50% stenosis, not on aspirin; high-risk patient with multiple TIAs, not on aspirin, stenosis < 50%; high-risk patient, mild or moderate stroke, stenosis < 50%, not on aspirin; global ischemic symptoms with stenosis < 50%; acute dissection, asymptomatic on heparin. Indications for carotid endarterectomy in asymptomatic good-risk patients performed by a surgeon whose surgical morbidity and mortality rate is less than 3% are as follows. (1) Proven: none. As this statement went to press, the National Institute of Neurological Disorders and Stroke issued a clinical advisory stating that the Institute has halted the Asymptomatic Carotid Atherosclerosis Study (ACAS) because of a clear benefit in favor of surgery for patients with carotid stenosis > or = 60% as measured by diameter reduction. When the ACAS report is published, this indication will be recategorized as proven. (2) acceptable but not proven: stenosis > 75% by linear diameter; (3) uncertain: stenosis > 75% in a high-risk patient/surgeon (surgical morbidity and mortality rate > 3%), combined carotid/coronary operations, or ulcerative lesions without hemodynamically significant stenosis; (4) proven inappropriate: operations with a combined stroke morbidity and mortality > 5%.

Guidelines for carotid endarterectomy. A multidisciplinary consensus statement from the ad hoc Committee, American Heart Association

BACKGROUND AND PURPOSE

Indications for carotid endarterectomy have engendered considerable debate among experts and have resulted in publication of retrospective reviews, natural history studies, audits of community practice, position papers, expert opinion statements, and finally prospective randomized trials. The American Heart Association assembled a group of experts in a multidisciplinary consensus conference to develop this statement.

METHODS

A conference was held July 16-18, 1993, in Park City, Utah, that included recognized experts in neurology, neurosurgery, vascular surgery, and healthcare planning. A program of critical topics was developed, and each expert presented a talk and provided the chairman with a summary statement. From these summary statements a document was developed and edited onsite to achieve consensus before final revision.

RESULTS

The first section of this document reviews the natural history, methods of patient evaluation, options for medical management, results of surgical management, data from position statements, and results to date of prospective randomized trials for symptomatic and asymptomatic patients with carotid artery disease. The second section divides 96 potential indications for carotid endarterectomy, based on surgical risk, into four categories: (1) Proven: This is the strongest indication for carotid endarterectomy; data are supported by results of prospective contemporary randomized trials. (2) Acceptable but not proven: a good indication for operation; supported by promising but not scientifically certain data. (3) Uncertain: Data are insufficient to define the risk/benefit ratio. (4) Proven inappropriate: Current data are adequate to show that the risk of surgery outweighs any benefit.

CONCLUSIONS

Indications for carotid endarterectomy in symptomatic good-risk patients with a surgeon whose surgical morbidity and mortality rate is less than 6% are as follows. (1) Proven: one or more TIAs in the past 6 months and carotid stenosis > or = 70% or mild stroke within 6 months and a carotid stenosis > or = 70%; (2) acceptable but not proven: TIAs within the past 6 months and a stenosis 50% to 69%, progressive stroke and a stenosis > or = 70%, mild or moderate stroke in the past 6 months and a stenosis 50% to 69%, or carotid endarterectomy ipsilateral to TIAs and a stenosis > or = 70% combined with required coronary artery bypass grafting; (3) uncertain: TIAs with a stenosis < 50%, mild stroke and stenosis < 50%, TIAs with a stenosis < 70% combined with coronary artery bypass grafting, or symptomatic, acute carotid thrombosis; (4) proven inappropriate: moderate stroke with stenosis < 50%, not on aspirin; single TIA, < 50% stenosis, not on aspirin; high-risk patient with multiple TIAs, not on aspirin, stenosis < 50%; high-risk patient, mild or moderate stroke, stenosis < 50%, not on aspirin; global ischemic symptoms with stenosis < 50%; acute dissection, asymptomatic on heparin. Indications for carotid endarterectomy in asymptomatic good-risk patients performed by a surgeon whose surgical morbidity and mortality rate is less than 3% are as follows. (1) Proven: none. (As this statement went to press, the National Institute of Neurological Disorders and Stroke issued a clinical advisory stating that the Institute has halted the Asymptomatic Carotid Atherosclerosis Study (ACAS) because of a clear benefit in favor of surgery for patients with carotid stenosis > or = 60% as measured by diameter reduction. When the ACAS report is published, this indication will be recategorized as proven. (2) acceptable but not proven: stenosis > 75% by linear diameter; (3) uncertain; stenosis > 75% in a high-risk patient/surgeon (surgical morbidity and mortality rate > 3%), combined carotid/coronary operations, or ulcerative lesions without hemodynamically significant stenosis; (4) proven inappropriate: operations with a combined stroke morbidity and mortality > 5%.

Popliteal vein entrapment presenting as deep venous thrombosis and chronic venous insufficiency

PURPOSE

This report describes popliteal vein entrapment in three patients and demonstrates that it may present with manifestations of typical venous disease.

METHODS

This report was compiled from a review of inpatient and outpatient records.

RESULTS

In the first case, a 28-year-old woman was seen with left leg popliteal and calf deep vein thrombosis without obvious cause. She described long-standing calf discomfort, and passive dorsiflexion of the left foot caused disappearance of arterial pulsations at the pedal level. She was given the anticoagulants heparin and sodium warfarin (Coumadin) followed by surgical exploration. The popliteal vein and artery were entrapped by a fibrous extension of the medial head of the gastrocnemius muscle attaching to the lateral femoral condyle. After band lysis, the patient has been symptom free for 6 years. The second patient, a 37-year-old man, was seen with bilateral chronic venous insufficiency (CVI). Passive dorsiflexion and active plantar flexion of the feet did not diminish the pedal pulses; impedance plethysmography suggested mild outflow obstruction. Ascending venography demonstrated entrapment at the midportion of duplicated popliteal veins with no postthrombotic changes. He was treated with compression stockings and has done well during an 18-month follow-up. The third patient, a 17-year-old male, was seen with severe symptoms of right leg CVI and venous obstruction since 3 years of age. Air plethysmography revealed ambulatory venous hypertension, whereas venography demonstrated reflux down to the knee with an extrinsic narrowing at the midpopliteal vein. During operation, an abnormal origin of the lesser saphenous vein (LSV) from the popliteal vein was found; the LSV took a medial route, compressed the tibial nerve, and caused severe distortion and narrowing of the popliteal vein. Division of the LSV resulted in release of popliteal venous compression and immediate relief of symptoms.

CONCLUSIONS

The three cases presented demonstrate that popliteal venous entrapment may begin with symptoms of deep vein thrombosis and CVI. Popliteal venous entrapment must be considered in the differential diagnosis of venous disease in younger patients in whom common predisposing factors are absent.

Endoscopic variceal sclerotherapy as primary treatment for bleeding esophageal varices

In this study of 75 patients with bleeding esophageal varices we confirm not only the ability of endoscopic variceal sclerotherapy (EVS) to control acute bleeding episodes but to effect variceal obliteration that confers a significant survival advantage, regardless of initial Child's classification. Survival correlates directly with the degree of hepatic dysfunction, although all patients regardless of Child's status have a statistically significant survival advantage when treated until esophageal variceal obliteration is achieved. All patients treated with EVS should be followed for life, but virtually all follow-up can be done on an outpatient basis. Shunt surgery should be reserved for: (a) patients whose acute bleeding cannot be controlled with EVS at the time of index bleed; and (b) patients who rebleed repeatedly or uncontrollably from gastric or duodenal varices. EVS is more cost-effective than other available treatments. It also effectively stabilizes potential candidates for orthotopic liver transplantation. Despite a progressive increase in the admissions for bleeding varices at our institution, the introduction of EVS has been associated with a significant decline in portosystemic shunt therapy. We believe that EVS is now the first-line treatment for all patients with bleeding esophageal varices.

Carotid artery stump pressure: its variability when measured serially

At 189 operations in 174 patients, carotid artery stump pressure (CSP) was measured serially to determine variability during carotid endarterectomy with eucarbic general anesthesia. Overall, 34 of 174 (19.5%) had significant variation in CSP which would have affected selective use of a bypass shunt based on CSP criteria. In those with CSP initially below 50 torr, 26 of 76 (34%) rose above 50 torr even, though systemic pressure was constant or declined. Eight of 113 pts (7%) with initial CSP equal to or above 50 torr subsequent had CSP below 50 torr. CSP did not vary as a function of age, sex, intracranial disease judged by biplanar arteriography, or contralateral carotid stenosis but did vary with preoperative status. Asymptomatic patients had CSP above 50 torr in a high proportion of cases, 24 of 27 (89%) unlike those with TIA, 72 of 116 (62%) or prior stroke, 17 of 31 (54%) (P = 0.003). We conclude that carotid stump pressure is variable in many patients which may account for some of the conflicting observations on the need for shunts in carotid surgery.

Progress in chronic mesenteric arterial ischemia

Analysis of surgical treatment for chronic mesenteric arterial occlusive lesions in 45 patients between 1964 and 1986 has shown an evolution in diagnostic criteria, indications for operation, and surgical technique. Prior to 1976, a variety of surgical procedures (diaphragmatic crus release, arterial dilation, patch angioplasty, reimplantation, endarterectomy) were employed in treatment of patients with a wide range of symptoms and variation in number of mesenteric vessels involved. Since 1976, we have selected patients with "typical" symptoms (postprandial epigastric pain, fear of eating, weight loss) and 2 or 3 vessel disease, and have avoided surgery for celiac crus lesions. Typical symptoms were seldom present in isolated celiac artery crus compression, 4 of 15 pts (23%), but were often present with 2 or 3 vessel disease, 17 of 28 pts (61%, p = 0.03). Satisfactory resolution of pain was achieved in 18 of 24 pts with 2 or 3 vessel disease. We conclude that presence of "typical" symptoms and angiographic findings of 2 or 3 vessel disease are prerequisites for effective surgical treatment. Bypass graft is our surgical technique of choice, but the extent of arterial reconstruction required to relieve symptoms remains undefined.

Assessing risk associated with carotid endarterectomy. A statement for health professionals by an Ad Hoc Committee on Carotid Surgery Standards of the Stroke Council, American Heart Association

This position statement provides guidelines for assessing risk associated with carotid endarterectomy and defines the point at which risk is too high to perform surgery for specific indications described below. Morbidity and mortality levels are discussed. This statement does not address indications for surgery or merits of specific medical or surgical treatments. Results of current studies that compare relative risk of various treatments for carotid artery disease are not yet available.

Results of renal artery balloon angioplasty limit its indications

Percutaneous transluminal balloon angioplasty (PTA) of 83 renal artery lesions in 55 patients was done because of renal failure in eight patients, hypertension in 35, renal failure and hypertension in 11, and polycythemia in one patient. Early results in 38 patients with arteriosclerosis showed five (13%) were worse and 13 (34%) were unchanged. Twenty patients (53%) with arteriosclerosis were initially cured or improved; however, seven of these patients had recurrence in 4 to 48 months. Ultimately, only 13 of 38 patients with arteriosclerosis (34%) were cured or improved (mean follow-up 22 months). Nine patients with fibromuscular dysplasia required 17 dilatations of arteries (three bilateral and five repeat), resulting in eight patients (89%) who were cured or improved. Selection of patients with hypertension by medical failure while receiving three or more hypertension medications or by lateralizing renal vein renin values yielded benefit in 17 of 26 patients (65%). Five of six patients with transplant stenosis of the renal artery and hypertension were cured or improved at mean follow-up of 18 months. Overall technical results of 83 artery dilatations were as follows: good, 58 (69%); fair, 10 (12%); poor or unsatisfactory, 16 (19%); these were judged with a blinded radiologic review. No patient suffered main renal artery thrombosis. There were 16 patients with complications of dilatation (morbidity rate of 29%). Nine patients subsequently had renal artery surgery from the same day to 64 days later with good results in all patients except one.(ABSTRACT TRUNCATED AT 250 WORDS)

Antegrade aortorenal bypass graft: a new alternative

The search for a site of origin for renal artery bypass grafting other than the inclusion aorta has resulted in a variety of recommendations, including use of the splenic, hepatic, gastroduodenal, and superior mesenteric arteries and even retrograde bypass grafts originating from the iliac artery. The present study has described our early experience with a new procedure utilizing an antegrade aortorenal bypass graft originating in the mediastinal supraceliac aorta. Eight patients underwent operation; four for renovascular hypertension and four for renal salvage plus hypertension. There were no operative deaths. All grafts (three saphenous and five polytetrafluoroethylene) functioned well, as judged by clinical response and renal scan. One graft failed at 6 weeks. Hypertension was cured in three patients and improved in four at a mean follow-up of 27 months (range 3 to 58 months). Improved hemodynamic performance of antegrade flow, avoidance of liver and biliary complications, and applicability to the right or left kidney are the advantages of this technique. When renal artery reconstruction is required and the infrarenal aorta is to be avoided, we believe this operation is a useful alternative.

Supraceliac aortomesenteric bypass for intestinal ischemia

The supraceliac aorta has received little attention as an inflow site of bypass graft origin for mesenteric arterial reconstruction; this article describes our experience with its use in 10 patients. Ten patients underwent bypass grafts (three vein and seven prosthetic grafts) from the supraceliac aorta incorporating the celiac axis to the superior mesenteric artery. All patients had two- or three-vessel mesenteric arterial occlusion. No operative deaths occurred. Nine patients were studied with postoperative arteriography. Nine of ten patients have had satisfactory results on follow-up from 5 to 99 months (mean 43 months), although two patients required operative revision to achieve this. The operative technique is described, including approach to the aorta in the lower mediastinum via upper abdominal exposure and pancreatic displacement to expose the superior mesenteric artery. This method permits avoidance of the infrarenal aorta, if desired because of atherosclerotic disease or previous operation. Antegrade supraceliac aortomesenteric grafts avoid turbulence and compression of conventional "retrograde" bypass beneath the mesentery. We conclude that supraceliac aortic grafts provide a useful visceral artery reconstruction technique.

Choices of operation for subclavian-vertebral arterial disease

Subclavian-vertebral artery disease requires careful delineation of symptoms and offers a wide selection of operative procedures. The transition over a 10 year period from intra- to extrathoracic operations in a series of 35 patients is described.

Gracilis muscle flap for closure of rectourethral fistula

A gracilis muscle flap can be used to close a rectourethral fistula caused by operative trauma and radiation. The flap is rotated easily into the perineum, brings vascularized muscle to irradiated and/or traumatized tissue and is a mechanical barrier between the urethra and the rectum.

Case reports. Cavernous hemangioma of the liver presenting with fever. Successful treatment with prednisone

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An evaluation of the Mobin-Uddin umbrella in the prevention of pulmonary thromboembolism

A vena caval umbrella was implanted in twenty-eight patients for the prevention of recurrent pulmonary embolism. Eighteen of these patients were catastrophically ill at the time of reimplantation. Thirteen patients died after implantation, one from a recurrent pulmonary embolus originating in the vena cava. There have been two additional recurrent nonfatal emboli. Three of the thirteen long-term survivors had significant lower extremity edema. Our experience and that of others indicates that the inferior vena caval umbrella is comparable to other methods of incomplete interruption in terms of effectiveness, morbidity, and mortality. Its unique technical advantage is the simplicity of insertion in severely ill patients in whom abdominal surgery is undesirable.