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Biomedical subjects

O W Brown

Publications and source records attributed to O W Brown.

At least 19 recordsLinked to original sources
PubMed2003

Transrenal fixation of endovascular stent-grafts for infrarenal aortic aneurysm repair: mid-term results.

PURPOSE: We evaluated mid-term results of a single-center consecutive series of endovascular stent-grafts implanted for aortic aneurysm repair with transrenal fixation, to determine clinical outcome, aneurysm anatomy, renal artery patency, and renal complications. METHODS: Modular stent-grafts were placed with transrenal fixation in 37 patients between November 1998 and July 2000. Follow-up evaluation included clinical examination, laboratory evaluation of serum creatine concentration, computed tomographic angiography, and renal duplex scanning. RESULTS: Thirty-seven patients underwent transrenal fixation of aortic stent-grafts as part of a Phase II US Food and Drug Administration study. Two patients subsequently underwent follow-up at institutions closer to their homes, and thus provided clinical information but no long-term renal or aneurysm morphologic data. There were no perioperative deaths. Five patients died during follow-up, at a mean of 9 months, because of myocardial infarction in 4 patients and respiratory failure in 1 patient. Thirty patients, ages 75 +/- 8 years, have been followed up for 28.5 +/- 7.2 months. Aneurysm diameter at follow-up was 5.0 +/- 0.8 cm, compared with 5.7 +/- 0.8 cm preoperatively. In 5 patients, endoleak developed during follow-up: 1 type I leak was treated with an aortic cuff, with temporary stabilization of the aneurysm and correction of the endoleak; 2 type II endoleaks were treated with translumbar coil embolization, and 1 resolved spontaneously; and 1 type III endoleak was treated with a combination of coil embolization and stent-graft extension to cover a graft defect. Preoperatively, serum creatinine concentration was normal in 23 patients, but increased persistently in 2 patients and was abnormal in 7 patients. Postoperatively, creatine concentration increased in 4 patients to greater than 20% of baseline level. Seventeen patients had no evidence of renal artery stenosis, compared with 13 patients with renal artery stenosis. Of 41 normal renal arteries, 90% remained unchanged, 1 became occluded, 3 demonstrated 60% stenosis. Nephrectomy was necessary in 1 patient because of cancer. Of 19 abnormal renal arteries, progression of disease was noted in 3 arteries. CONCLUSIONS: Transrenal fixation of aortic stent-grafts can be performed with acceptable mid-term outcome with respect to mortality, need for follow-up intervention, and aneurysm exclusion with protection from rupture. Postprocedural stenosis can develop in both normal and abnormal renal arteries. Rate of progression of disease was greater in patients with preprocedural renal dysfunction compared with patients with normal renal arteries. This is merely an observation, and may not be related to transrenal fixation. Long-term follow up is needed.

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PubMed1998

Three-dimensional vascular imaging using Doppler ultrasound.

BACKGROUND: We have evaluated the efficacy of using three-dimensional reconstruction of amplitude Doppler imaging data to quantitatively assess carotid artery bifurcation stenoses. METHODS: Sixty-four consecutive frames of amplitude (power) Doppler images are stored to be reassembled into a three-dimensional image representing the patent lumen. These images can then be rotated by any angle necessary to clearly view the vascular anatomy and to make quantitative ultrasound caliper measurements of the stenotic lumen and normal vessel caliber. RESULTS: Three-dimensional Doppler images accurately classified 53 of 61 vessels (87%) into categories of stenosis compared with angiography. All stenoses with >60% diameter reduction were detected and classified as such, for a sensitivity of 100%. CONCLUSIONS: Three-dimensional vascular imaging based on amplitude (power) Doppler data provides an accurate noninvasive technique for quantitative diagnosis of carotid bifurcation atherosclerotic disease, with selectable viewing projections that eliminate vessel overlap and other artifacts, and complements the hemodynamic data already available with two-dimensional duplex ultrasound.

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PubMed1996

Serial duplex ultrasound examinations for deep vein thrombosis in patients with suspected pulmonary embolism.

PURPOSE: We have prospectively evaluated the need for serial venous duplex ultrasound examinations in an inpatient population with an initially normal study result. METHODS: Patients were selected for study on the basis of clinical suspicion of pulmonary embolism and possible lower extremity deep vein thrombosis, a comorbid condition contributing to a nondiagnostic ventilation/perfusion lung scan, and an initially normal bilateral venous duplex ultrasound examination that included complete evaluation of the femoropopliteal system and the deep calf veins. Repeat duplex examinations were done during the same hospital admission between 5 and 14 days after the initial study. RESULTS: Ninety-four patients with an initially normal duplex ultrasound examination result had repeat studies done at an average of 7.9 +/- 2.6 days. Ninety-two examination results remained normal bilaterally. Two patients had isolated intramuscular calf vein deep vein thrombosis: one in the gastrocnemius system of both calves with associated calf tenderness at 11-day follow-up and one in a mid-calf soleal vein without associated symptoms at 10 days. No patients had any evidence of deep vein thrombosis in the femoropopliteal or tibioperoneal venous systems. CONCLUSIONS: Serial follow-up duplex ultrasound evaluation is unnecessary after an initially complete, normal study in patients with symptoms who have suspected pulmonary embolism and nondiagnostic ventilation-perfusion lung scans.

Adult↗
PubMed1996

Progression of superficial venous thrombosis to deep vein thrombosis.

PURPOSE: We have evaluated the progression of isolated superficial venous thrombosis to deep vein thrombosis in patients with no initial deep venous involvement. METHODS: Patients with thrombosis isolated to the superficial veins with no evidence of deep venous involvement by duplex ultrasound examination were evaluated by follow-up duplex ultrasonography to determine the incidence of disease progression into the deep veins of the lower extremities. Initial and follow-up duplex scans evaluated the femoropopliteal and deep calf veins in their entirety; follow-up studies were done at an average of 6.3 days, ranging from 2 to 10 days. RESULTS: From January 1992 to January 1996, 263 patients were identified with isolated superficial venous thrombosis. Thirty (11%) patients had documented progression to deep venous involvement. The most common site of deep vein involvement was progression of disease from the greater saphenous vein in the thigh into the common femoral vein (21 patients, 70%), with 18 of these extensions noted to be nonocclusive and 12 having a free-floating component. Three patients had extended above-knee saphenous vein thrombi through thigh perforators to occlude the femoral vein in the thigh, three patients had extended below-knee saphenous disease into the popliteal vein, and three patients had extended below-knee thrombi into the tibioperoneal veins with calf perforators. At the time of the follow-up examination all 30 patients were being treated without anticoagulation. CONCLUSIONS: Proximal saphenous vein thrombosis should be treated with anticoagulation or at least followed by serial duplex ultrasound evaluation so that definitive therapy may be initiated, if progression is noted. More distal superficial venous thrombosis should be carefully followed clinically and repeat duplex ultrasound scans performed, if progression is noted or patient symptoms worsen.

Adult↗
PubMed1994

Penetrating atherosclerotic ulcers of the aorta.

PURPOSE: This study investigates the natural history and optimal imaging modality of penetrating atherosclerotic ulcers of the aorta. METHODS: We reviewed our experience with 29 penetrating ulcers in 18 patients. Computed tomography (17 patients), magnetic resonance imaging (nine patients), and aortography (five patients) were used for diagnosis and follow-up. Patients were typically elderly (average age 74 years) and had hypertension and coronary artery disease. Ulcers were most common in the distal descending thoracic aorta (31%) and were characterized by a discrete ulcer crater (100%) and thickened aortic wall (89%). Modes of presentation included chest or back pain in four patients, distal embolization in two patients, and abnormal chest radiography results in one; the remaining were incidental findings. RESULTS: Follow-up was available in ten patients with 17 ulcers from 1 to 7 years. Recurrent pain occurred in two patients, recurrent embolization occurred in one patient, and seven patients remained symptom free. Progression to saccular pseudoaneurysm occurred in five ulcers, and fusiform aneurysm occurred in two ulcers. Two ulcers were associated with an increase in aortic diameter, and nine ulcers did not change. There were no cases of aortic dissection or rupture in the follow-up period. There were no deaths and only one patient underwent resection. CONCLUSION: The natural history of penetrating atherosclerotic ulcers is one of progressive aortic enlargement, with saccular and fusiform aneurysms the result if follow-up is sufficient. Aortic dissection, aortic rupture, and embolization can also occur but are less common. Contrast-enhanced computed tomography is the primary imaging modality.

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PubMed1993

Cell washing versus immediate reinfusion of intraoperatively shed blood during abdominal aortic aneurysm repair.

Significant hematologic changes are known to occur following intraoperative autotransfusion of shed blood, but the clinical importance of cell washing prior to reinfusion has not been substantiated. To evaluate these changes and their relationship to the use of blood bank products and postoperative morbidity, 26 patients undergoing elective abdominal aortic aneurysm repair were prospectively randomized to reinfusion with washed shed blood or to the use of a collection system in which filtered, but unwashed, whole blood was reinfused intraoperatively. Each patient was evaluated with respect to standard metabolic and hematologic laboratory parameters preoperatively, immediately postoperatively, and 12 to 18 hours postoperatively. Patient demographic data were similar for both groups. Perioperative survival was 100% for both groups. Total blood loss and blood volume autotransfused were significantly greater in the unwashed cell group compared with the washed cell group (p = 0.00014 and p = 0.00011, respectively). Hemoglobin, fibrinogen, prothrombin time, and partial thromboplastin time levels were not significantly different between the two groups at any time perioperatively; fibrin split product and d-dimer levels were significantly higher in the unwashed cell group postoperatively (p = 0.016 and p < 0.001, respectively). Serum free hemoglobin levels were significantly higher in the immediate postoperative period in the unwashed cell group compared with the washed cell group (p = 0.0013); by 12 to 18 hours postoperatively, this difference was not significant. Haptoglobin levels were significantly lower in the unwashed cell group at both postoperative times (123 +/- 86 mg/dL versus 41 +/- 50 mg/dL, p = 0.0086; 102 +/- 66 mg/dL versus 24 +/- 36 mg/dL, p = 0.0001); however, there was no perioperative renal failure in either group. Furthermore, homologous blood product use was not significantly different between the two groups, with an average of 1.5 +/- 2.5 units of packed red blood cells given to patients in the unwashed cell group versus 0.8 +/- 1.7 units in the washed cell group (p = 0.419). Overall complications were higher and critical care and total hospital stays were longer in the unwashed cell group but did not result from autotransfusion of unwashed blood. We conclude that the intraoperative reinfusion of unwashed shed blood is safe and effective, causing transient hematologic abnormalities that normalize in the early postoperative period, and is not associated with increased mortality, or hematologic, cardiopulmonary, or renal complications.

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PubMed1992

Hemodynamic effects of primary closure versus patch angioplasty of the carotid artery.

This study evaluated the hemodynamic changes associated with patch angioplasty compared to primary closure of the canine carotid artery. A standard arteriotomy was closed either primarily, with a 5x28 mm expanded polytetrafluoroethylene (ePTFE) patch, or with a 10x28 mm ePTFE patch. Measurements for the primary closure group showed a systolic pressure gradient of 17 mmHg across the closure and a peak systolic velocity increase of 58% at mid-closure compared to proximal inflows. Flow turbulence increased at mid-closure in the 10 mm patch group, with the percent spectral window lowered from 0.50 to 0.36. These data show that primary vessel closure creates a mild local stenosis with flow acceleration but no flow turbulence. No significant hemodynamic disturbances are caused by a moderate sized patch; however, a large patch relative to native vessel dimensions creates marked flow disturbances throughout the cardiac cycle. As turbulence and flow separation are felt to contribute to restenosis, care should be taken in the selection of patch size when used following carotid endarterectomy.

Angioplasty↗
PubMed1986

Control of hypertension following carotid endarterectomy.

The role of carotid endarterectomy in the treatment of extracranial carotid artery disease has been well established. Postoperative hypertension is a significant prognostic factor and is associated with an increased incidence of both transient and permanent neurologic deficits. We studied 110 patients undergoing unilateral carotid endarterectomy to review the efficacy of the drug combination of hydralazine and propranolol to treat postoperative hypertension. All patients receiving hydralazine and propranolol had their blood pressure controlled postoperatively, and no patients developed hypotension, myocardial infarction, or postoperative neurologic deficits. There were no mortalities in the study group. We conclude that propranolol-hydralazine therapy is a safe and effective means to control hypertension associated with carotid endarterectomy.

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PubMed1986

Septic deep vein thrombosis.

Anticoagulation is the cornerstone in the treatment of deep vein thrombosis. However, the treatment of septic deep vein thrombosis is controversial. Unlike septic superficial vein thrombosis, venous excision is often associated with limb-threatening or even life-threatening complications. Some authors have suggested thrombectomy as the only means of resolving the sepsis. We reviewed our experience with seven patients who had septic deep vein thrombosis. Phlebography or noninvasive studies documented deep vein thrombosis and blood cultures were positive in all patients. The mean age was 31.5 years with a male/female ratio of 5:2. All patients were treated with anticoagulants and intravenous antibiotics. One patient required surgical exploration for associated abscess of the groin. The patients became afebrile with normal white blood cell counts from 3 to 18 days after therapy was begun. No cases of recurrent sepsis occurred. We conclude that antibiotic therapy and anticoagulation are adequate treatment and therefore consider venous thrombectomy unnecessary.

Adult↗
PubMed1985

Intravascular monitoring via the axillary artery.

Axillary artery cannulation was performed in 31 patients in whom the radial arteries were unavailable or unsuitable for cannulation. The artery was first cannulated with an 18-gauge needle, after which a Seldinger guide wire (0.032-inch diameter) was passed, which was used to introduce a 6-inch, 18-gauge Teflon catheter. The mean duration of cannulation was 3.2 days (range 19 hours to 8 days). All patients were assessed for complications of the procedure up to 72 hours after decannulation. No serious complications were encountered. It is concluded that the axillary artery is a safe alternative in the absence of an available radial artery when arterial cannulation is indicated.

Axillary Artery↗
PubMed1985

Extensive revascularization in patients with "nonreconstructible" vascular disease.

Elderly patients with severely ischemic lower extremities should undergo thorough noninvasive and angiographic evaluation. Although the visualization of a small nongraftable vessels in the lower extremity is a contraindication to an extensive limb salvage procedure, the inability to visualize angiographically any distal vessels in the lower extremity is not a contraindication. Patients with a severely ischemic but viable lower extremity and angiographic nonvisualization of any distal vessels of the lower extremity should be considered potential candidates for surgical exploration and possible salvage by simultaneous inflow and outflow procedures.

Amputation, Surgical↗
PubMed1985

Carotid endarterectomy in the stroke patient: computerized axial tomography to determine timing.

Historically, patients with mild to moderate neurologic deficits lasting longer than 24 hours were believed to have sustained a completed stroke. They were followed up for 4 to 6 weeks and cerebral angiography was performed if indicated. CT scanning has identified a subset of these patients who have sustained a reversible ischemic neurologic deficit (RIND) rather than a completed stroke. The timing for angiography and surgery for this group has not been established. In an earlier study we found that 21% (4 of 19 patients) suffered a second stroke during the 4- to 6-week waiting period. To avoid this high rate of recurrence, we instituted an aggressive program of CT scan evaluation and surgical therapy for all "stroke patients" with negative CT scans. Two hundred forty-five patients were seen with a persistent neurologic deficit between July 1980 and December 1983. These patients underwent CT scans 1 and 5 days after the initial event. Of these 245 patients, 171 patients (70%) were found to have negative CT scans. Appropriate carotid lesions were found by arteriography in 110 (64%) of the negative CT scan group. There were 61 (55%) men and 49 (45%) women in this group. Eighty-five patients (77%) had previous neurologic symptoms or a cerebrovascular accident. Hypertension was present in 52% and diabetes mellitus in 30%. All 110 patients underwent carotid endarterectomy within 14 days (mean 10 days) of the initial onset of their neurologic deficit; these were all done with shunt protection. No patient suffered another neurologic deficit in the same territory within 30 days after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Carotid Arteries↗
PubMed1984

Alternative sites for continuous arterial monitoring.

During a 13-month period, we studied 148 patients who had percutaneous arterial cannulation for continuous intraoperative, postoperative, and intensive care monitoring. In all patients, alternative arteries were cannulated, which included the brachial (43%), axillary (19%), femoral (28%), dorsalis pedis (8%), and superficial temporal artery (1%). No patient sustained any functionally significant or serious complication requiring surgical intervention. Eighteen patients (12%) had minor, clinically insignificant complications. We conclude that in the absence of an available radial artery, there are at least five other reliable arterial sites that may be cannulated and safely used when direct arterial monitoring is required.

Adult↗
PubMed1983

Uncommon visceral artery aneurysms.

Aneurysms of the hepatic, celiac, and superior mesenteric arteries are uncommon visceral artery aneurysms. They are often difficult to diagnose, and symptoms of expansion or rupture may easily be misinterpreted as suggestive of primary gastrointestinal disease. These aneurysms appear to have a significant propensity toward rupture. Indications for surgery include an aneurysm three to four times the original size of the vessel, x-ray evidence of increasing size of the aneurysm, or a calcified aneurysm larger than 3 cm. We believe that in all patients who are acceptable surgical candidates, a diagnosed visceral artery aneurysm should be resected.

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