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Biomedical subjects

A W Stanson

Publications and source records attributed to A W Stanson.

At least 37 records · Page 2Linked to original sources
PubMed1996

Primary aldosteronism: adrenal venous sampling.

BACKGROUND: In primary aldosteronism, high-resolution adrenal computed tomography (CT) increasingly identifies subtle anatomic abnormalities. To interpret the functional significance of adrenal micronodular changes on CT scan, we have reevaluated selective adrenal venous sampling. METHODS: Thirty-four patients with primary aldosteronism were selected prospectively for adrenal venous sampling on the basis of CT findings: normal findings or minimal thickening of an adrenal limb (n = 15), unilateral microadenoma (n = 6), bilateral adrenal nodules (n = 9), or atypical unilateral adrenal macroadenoma (n = 4). RESULTS: Both adrenal veins were catheterized in 33 of 34 patients. Six (40%) of 15 patients with normal or minimal adrenal limb thickening had a unilateral source of aldosterone. Six patients with apparent unilateral microadenoma had ipsilateral aldosterone-producing adenomas. Four (44%) of nine patients with bilateral adrenal masses had a unilateral source of aldosterone secretion. Three of four patients with unilateral atypical adrenal macroadenomas had ipsilateral aldosterone-producing adenomas. CONCLUSIONS: A unilateral source of aldosterone excess may be found in selected patients with adrenal glands that appear normal or show a minimally expanded adrenal limb on CT scan. Findings on adrenal venous sampling are crucial in determining the source of aldosterone excess in patients with bilateral adrenal masses or atypical-appearing macroadenomas.

Adenoma↗
PubMed1995

Preoperative highly selective catheter localization of occult small-intestinal hemorrhage with methylene blue dye.

In patients with occult lower gastrointestinal bleeding, locating of the source of the hemorrhage can be quite difficult. While multiple diagnostic tests may confirm a small bowel source of bleeding, precise localization allowing a directed, conservative surgical resection may be problematic. We describe three patients each of whom presented with hemorrhage from the small intestine. The preoperative use of highly selective angiographic catheter placement combined with intraoperative methylene blue dye injection allowed us to precisely locate the source of hemorrhage and to resect a conservative length of small intestine. This technique has been successful in the three patients herein, and we believe that it should be included in the options available to the surgeon.

Adult↗
PubMed1995

Renal artery anomalies in patients with horseshoe or ectopic kidneys: the challenge of aortic reconstruction.

Renal fusion or ectopia can present formidable challenges during aortic surgery. To evaluate morbidity and define optimal management, the clinical histories of 20 patients with renal fusion or ectopia who underwent 21 aortic procedures at the authors' institution over a 37-year period were reviewed. Indications for surgery included aortic aneurysm in 16 patients (infrarenal in 15 and thoracoabdominal in one) and aortoiliac occlusive disease in five (with renovascular hypertension in two). The abnormal kidney was detected before surgery in 13 patients (65%) by excretory urography, arteriography, computed tomography, or ultrasonography. Arteriography revealed multiple and/or anomalous renal arteries in nine of 12 patients studied. At surgery, 15 patients (75%) were found to have multiple or anomalous renal arteries. Six required renal revascularization (reimplantation four, endarterectomy one, aortorenal bypass one). The renal symphysis was divided in two patients. There were no operative deaths. Six major complications included bleeding requiring reoperation, renal failure requiring short-term dialysis, pancreatitis, gastrointestinal bleeding, pneumonia and thrombophlebitis. Preoperative aortography is recommended in patients with renal fusion or ectopia because of the high incidence of associated renal artery anomalies. The surgeon must be prepared to preserve or revascularize these anomalous renal arteries. Division of the renal symphysis is rarely required. Although perioperative morbidity is raised, aortic reconstruction in patients with renal fusion or ectopia can be safely performed without increased mortality.

Aged↗
PubMed1995

Outcome and expansion rate of 57 thoracoabdominal aortic aneurysms managed nonoperatively.

BACKGROUND: The prognosis of thoracoabdominal aortic aneurysms (TAAAs) managed nonoperatively is unknown. PATIENTS AND METHODS: To determine the risk of rupture and survival, we retrospectively reviewed the clinical course and computed tomographic data of 57 patients who were evaluated for degenerative, nondissecting TAAAs. Nonoperative management was decided initially for all patients. Data of aneurysm expansion rate were available in 29 patients who underwent 2 or more scans. Follow-up was complete in 52 (91%) patients and averaged 37 months (range 1 to 82). RESULTS: Thirty-four of the 57 (60%) patients died during follow-up, including 3 of 15 patients who underwent subsequent repair of their aneurysm. Two- and 5-year survival rates for the entire group were 69% and 39%, with repair-free survival rates of 52% and 17%, respectively. Eight (14%) aneurysms ruptured, accounting for 24% (8/34) of the deaths. Two- and 4-year risks of rupture were 12% and 32%, respectively. The median expansion rate was 0.2 cm/y and was greater in patients with chronic obstructive pulmonary disease (P < 0.05). All ruptured aneurysms were > 5 cm in diameter. Aneurysms with a diameter > 5 cm at diagnosis had a higher rupture rate than those with a diameter < or = 5 cm (P < 0.05). Expansion rate did not predict rupture. CONCLUSIONS: Mortality of patients with TAAAs preselected for nonoperative management is high, with an overall survival rate of 39% and repair-free survival rate of only 17% at 5 years. Expansion rate of TAAAs (0.2 cm/y) is similar to that of abdominal aortic aneurysms. Our data that support nonoperative management for patients with TAAAs < 5 cm in diameter, but confirm the increase rate of rupture for aneurysms > 5 cm.

Aged↗
PubMed1995

Pulmonary embolism: diagnosis with contrast-enhanced electron-beam CT and comparison with pulmonary angiography.

PURPOSE: To determine the sensitivity and specificity of contrast material-enhanced electron-beam computed tomography (CT) in the diagnosis of pulmonary embolism (PE). MATERIALS AND METHODS: Sixty patients suspected of having PE were prospectively evaluated with pulmonary angiography and contrast-enhanced electron-beam CT. Thirty-eight patients underwent ventilation-perfusion (V-P [also known as V/Q]) scanning. The pulmonary vasculature was divided into 12 anatomic zones. CT and angiographic findings were correlated on a patient-by-patient basis and for each vascular zone. RESULTS: Both studies were negative for PE in 36 patients. Both studies were positive in 15 patients, with the site of the emboli correlating well. Prospective sensitivity of CT was 65%; specificity, 97%; positive predictive value, 94%; and negative predictive value, 82%. After review of the nine discordant cases, sensitivity and specificity approached 100% for clinically important acute PE. CT depicted central and peripheral emboli equally well. CT was more sensitive and specific than V-P scanning. CONCLUSION: Electron-beam CT is a sensitive and specific noninvasive method for the diagnosis of PE. It has the potential to replace V-P scanning as the primary screening examination for PE.

Humans↗
PubMed1995

Effects of body position on the upper airway of patients with obstructive sleep apnea.

Fast-CT scanning was used to study the effects of changes in body position on upper airway (UA) size and shape in 11 awake subjects with obstructive sleep apnea (OSA). Six patients with position (P)-dependent OSA were compared with five patients with nonposition (NP)-dependent OSA. Scans were repeated in the prone (PRN), right side (RS), and supine (SUP) body positions at both functional residual capacity and end-inspiratory tidal volume. Significant group, group by position, and borderline group by respiration effects were detected for minimum but not mean UA dimension data. Significant differences between groups were noted in minimum cross-sectional area and minimum lateral distance but not in minimum anteroposterior distance in the RS and SUP positions. Turning from the PRN to the RS or SUP position tended to decrease UA size in the NP group by decreasing the lateral distance, while the opposite effect was found in the P group. The results indicate that changes in body position during wakefulness affect the lateral but not the anteroposterior dimensions of the UA, and the UA behaves differently in patients with NP and P OSA in response to changes in body position.

Case-Control Studies↗
PubMed1995

Renal artery angioplasty: technical results and clinical outcome in 320 patients.

OBJECTIVE: To review the results of percutaneous transluminal renal artery angioplasty (PTRA), including technical success and clinical outcome, at Mayo Clinic Rochester. DESIGN: We retrospectively reviewed our experience with 320 patients who underwent PTRA for stenosis of 396 arteries during a 14-year period. MATERIAL AND METHODS: We reviewed medical records and angiograms of patients who underwent PTRA at Mayo Clinic Rochester between January 1980 and December 1993. The patients were divided into four groups, based on clinical history and angiographic appearance of the stenosing lesion: renal artery atherosclerosis (ASO group), fibromuscular dysplasia (FMD group), previous renal artery bypass or endarterectomy, and renal artery stenosis in a solitary kidney. Technical results of the PTRA were determined by evaluation of angiograms obtained before and after the procedure. Data on patient demographics, blood pressure, antihypertensive medications, and serum creatinine were recorded for the period preceding PTRA, after the procedure, and at last follow-up. RESULTS: All groups had statistically significant reductions in mean arterial pressure and antihypertensive medications after PTRA. The percentage of patients who benefited after renal artery angioplasty was 70% for patients with ASO (8.4% cured), 63% for patients with FMD (22% cured), 53.8% for patients with prior surgical revascularization (23.1% cured), and 91.7% for patients with a solitary kidney (0% cured). No significant overall change in serum creatinine level was noted after the procedure in any group. Complications were comparable to those reported in other studies. The 30-day all-cause mortality rate was 2.2% for the current study, all deaths occurring in the ASO group. CONCLUSION: PTRA rarely leads to a "cure" of renovascular hypertension but provides effective control of blood pressure and decreases the medication requirements in selected patients.

Adult↗
PubMed1995

Snare removal of a telectronics accufix atrial J retention wire.

A voluntary recall of the Telectronics Accufix models 330-801 and 329-701 "J"-shaped atrial pacemaker leads has been issued because of fracture and extrusion of the J-shaped retention wire. Such extrusion can result in laceration of the atrium or surrounding vascular structures. Herein we describe a patient with a fractured and extruded retention wire that was snared and removed percutaneously; the atrial lead was left intact, and pacing function was satisfactory. This unique procedure can be used to avoid the morbidity associated with percutaneous lead extraction or thoracotomy and to prevent potential dislodgment and embolization of the retention wire during lead extraction.

Child↗
PubMed1995

Rheumatoid vasculitis manifesting as intra-abdominal hemorrhage.

Rheumatoid vasculitis, an extra-articular component of rheumatoid arthritis, causes a wide spectrum of manifestations that range from clinically insignificant to life-threatening disease. As a systemic necrotizing arteritis, rheumatoid vasculitis is usually characterized by end-organ ischemia. Herein we describe a patient with abdominal pain and syncope due to intra-abdominal hemorrhage from a ruptured aneurysm of the inferior pancreaticoduodenal artery in the setting of rheumatoid vasculitis. Although the intra-abdominal hemorrhage was the unusual manifestation of rheumatoid vasculitis in this patient, he had a history of prior extra-articular rheumatoid disease, including pulmonary fibrosis and Sjögren's syndrome with associated parotid lymphoproliferative disease. In patients with rheumatoid arthritis who have abdominal pain and an unexplained rapidly decreasing hemoglobin concentration, the diagnosis of intra-abdominal hemorrhage from a ruptured visceral aneurysm due to rheumatoid vasculitis should be considered, even in the absence of other indications of systemic vasculitis.

Abdominal Pain↗
PubMed1995

Failure of hepatopulmonary syndrome to resolve after liver transplantation and successful treatment with embolotherapy.

The hepatopulmonary syndrome is an uncommon accompaniment of chronic liver disease. The outcome of this disorder after orthotopic liver transplantation is variable. We describe a patient with the hepatopulmonary syndrome who underwent orthotopic liver transplantation for autoimmune hepatitis. Her platypnea and orthodeoxia failed to improve postoperatively. Pulmonary angiography showed large pulmonary arteriovenous shunts that were successfully treated with coil embolotherapy.

Adult↗
PubMed1994

Symptomatic, nonruptured abdominal aortic aneurysms: are emergent operations necessary?

To evaluate current morbidity and mortality and to define the best strategy of management, we retrospectively reviewed the clinical histories of 36 patients (24 males and 12 females) who underwent repair of symptomatic, nonruptured abdominal aortic aneurysms (AAAs) between April 1, 1987, and April 30, 1992, at the Mayo Clinic (3.2% of 1111 patients with AAA repair). Ages ranged from 54 to 94 years (mean 75 years). All patients were hemodynamically stable and presented with abdominal and/or back pain of 1 to 60 days' duration (mean 11.6 days). The diagnosis of AAA was confirmed by CT scan in 26 patients, ultrasonogram in seven, and plain abdominal films in three. Fourteen patients (38.9%) were operated on emergently within 4 hours of admission, 11 (30.5%) between 4 and 24 hours, and 11 between 24 hours and 7 days following presentation (mean 28.9 hours). Eight (22.2%) had inflammatory aneurysm. AAAs were repaired with a straight graft in 17 patients and a bifurcated graft in 19. Complications occurred in 24 patients (66.7%). Mortality was 11.1% (4/36). The association between emergency repair (< 4 hours) and 60-day mortality was significant (p < 0.05). There were no deaths among those patients whose operation was delayed. Comparison to a matched control group of 72 patients who underwent elective AAA repair revealed an increased incidence of inflammatory aneurysm and female gender among our study group. The symptomatic patients had larger aneurysms (6.5 vs. 5.6 cm, p < 0.05) and required more intraoperative transfusions. Intensive care unit and hospital stay was longer in the symptomatic patients (p < 0.001); morbidity was markedly increased (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Microscope-aided pedal bypass is an effective and low-risk operation to salvage the ischemic foot.

BACKGROUND: The aim of this study was to determine the current operative risks of the pedal bypass procedure, its durability, and the factors affecting long-term outcome. METHODS: We prospectively observed 96 patients who consecutively underwent 100 pedal bypasses using autogenous vein grafts for chronic critical ischemia. Of the 100 limbs, 91 had ischemic ulcers or gangrene, and 9 produced rest pain only. Sixty-four patients were diabetic, 21 had renal failure, and 36 had coronary artery disease. Nonreversed saphenous vein grafts were used most frequently (68 translocated, 13 in situ), followed by composite (13) and reversed vein grafts (6). Fifty-two long grafts originated from the iliac or femoral arteries, and 48 short grafts originated from the popliteal or tibial arteries. For the 100 procedures, 102 distal anastomoses were performed--68 to the dorsalis pedis, 8 to the distal posterior tibial, 10 to the common plantar, 2 to the medial plantar, 9 to the lateral plantar, 4 to the lateral tarsal, and 1 to the first dorsal metatarsal arteries--with the aid of an operating microscope. RESULTS: No patient died during the perioperative period. Two had hemodynamically insignificant myocardial infarctions. Wound complications developed in 12 patients--infection in 7 and hematoma in 5. There were 10 early graft failures, 6 of which could be salvaged, and 96 grafts were patent at dismissal. Mean follow-up was 2.1 years (range 1 month to 6.4 years). Postoperative surveillance identified 33 failed or failing grafts, 16 of which were successfully revised. At 3 years, cumulative primary and secondary patency rates were 60% and 69%, respectively. Factors correlating with increased secondary patency were intraoperative flow rate > or = 50 mL/min (P = 0.004) and diabetes (P < 0.05). Major amputations were performed on 17 limbs. The cumulative foot salvage rate at 3 years was 79%. CONCLUSION: Pedal bypass is a safe, effective, and durable procedure. It should be considered even for high-risk patients with critical limb ischemia before major amputation is contemplated.

Adult↗
PubMed1994

Iliocaval complications of retroperitoneal fibrosis.

BACKGROUND: Retroperitoneal fibrosis can compress ureters, nerves, and blood vessels in the abdomen. However, clinically significant large-vein obstruction secondary to this process is rare. METHODS: Three hundred forty patients with retroperitoneal fibrosis were treated at our institution between 1976 and 1993. The clinical data from seven of these patients, who were treated for iliocaval complications of retroperitoneal fibrosis, were reviewed. RESULTS: Six patients had signs and symptoms of chronic obstruction, and one patient presented with acute iliocaval thrombosis and underwent attempt at venous thrombectomy in the referring hospital. All patients exhibited extremity edema and three had venous claudication. Iliocaval occlusion was confirmed in all patients by venography, computed tomography, or magnetic resonance imaging. The obstructive process involved the iliocaval tree (four patients), the inferior vena cava alone (two patients), and the iliac vein alone (one patient). Five patients were managed conservatively with leg elevation, compression stockings, and anticoagulation. Two patients received prednisone. One patient underwent an iliocaval bypass from the external iliac vein to the juxtarenal cava using a ringed polytetrafluoroethylene graft with a femoral arteriovenous fistula. A second patient with an isolated left common iliac vein obstruction underwent a left-to-right femorofemoral saphenous vein bypass. Four patients treated conservatively continued to have extremity edema. The two patients managed surgically remain asymptomatic from venous insufficiency, with patent grafts at 25 and 12 months after surgery, respectively. CONCLUSION: Iliocaval obstruction is an unusual complication of retroperitoneal fibrosis. Although most cases can be managed conservatively, reconstruction is an option for patients who have failed medical treatment and are symptomatic secondary to chronic venous obstruction. Lifelong anticoagulation should be considered for all patients with progressive iliocaval obstruction secondary to retroperitoneal fibrosis.

Acute Disease↗
PubMed1994

Budd-Chiari syndrome: early intervention with angioplasty and thrombolytic therapy.

We present a complex case of the Budd-Chiari syndrome due to thrombosis of the hepatic veins in the presence of stenosis of the left hepatic vein and membranous obstruction of the inferior vena cava. The acute thrombosis occurred after laparoscopic surgical removal of the gallbladder. Because we strongly suspected the Budd-Chiari syndrome, hepatic venography was performed. The hepatic venous outflow obstruction was relieved by angioplasty and thrombolytic therapy with use of local infusions of urokinase into the clot. We propose that angiography be performed in patients in whom the Budd-Chiari syndrome is suspected and that angioplasty and thrombolytic therapy be initiated early.

Adult↗
PubMed1994

Hepatic venous outflow obstruction in autosomal dominant polycystic kidney disease.

To discuss the clinical presentation, diagnosis, and treatment of hepatic venous outflow obstruction as a complication of polycystic liver disease, four cases diagnosed and treated at our institution have been reviewed and the information from six previously published case reports has been summarized. Eight of the 10 patients were women. All presented with severe ascites. Nine had polycystic kidneys. Three had moderate-to-advanced renal insufficiency, four were on hemodialysis, and one had a renal allograft. Possible predisposing factors were identified in seven patients; the most common was recent abdominal surgery, which, in three cases, was a bilateral nephrectomy. All patients had extrinsic compression of the hepatic veins and the inferior vena cava by hepatic cysts, and four had proven superimposed thrombosis of the inferior vena cava and/or hepatic veins. In the patients seen in this institution, magnetic resonance imaging was helpful in determining the level of obstruction in the inferior vena cava and the patency of the hepatic and portal veins. The outcome was worse in the patients with thrombosis; one recovered after a portocaval shunt, and the remaining three patients died. On the other hand, five of the six patients without thrombosis recovered after alcohol sclerosis of a large dominant cyst (one patient) or after hepatic resection and cyst fenestration (four patients). Hepatic venous outflow obstruction probably has been underrecognized as a cause of portal hypertension, ascites, and liver dysfunction in polycystic liver disease. The diagnosis can be reliably established with current imaging techniques, especially magnetic resonance imaging.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Clinical features and differential diagnosis of aortic dissection: experience with 236 cases (1980 through 1990).

Acute aortic dissection is the most common fatal condition that involves the aorta; nevertheless, despite major advances in noninvasive diagnosis, the correct antemortem diagnosis is made in less than half the cases. To promote continued improvement in the prompt recognition of aortic dissection, we present a review of the Mayo Clinic experience with 235 patients who had 236 substantiated aortic dissections. At the time of initial assessment, 158 patients (67%) had acute and 78 patients (33%) had chronic aortic dissection. Hypertension was the most common predisposing factor (78% of patients overall). The acute onset of severe chest pain was the most common initial complaint (74%), but 33 patients (15%) had painless aortic dissection and abnormal chest roentgenographic findings. Less common manifestations included congestive heart failure, syncope, cerebrovascular accident, shock, paraplegia, and lower extremity ischemia. The initial clinical impression was aortic dissection in 62% of patients overall. In 17 patients (28%), the correct diagnosis was not made before postmortem examination. Although the clinical features of aortic dissection have gained wider appreciation, the diagnosis still remains unsuspected in a substantial number of patients. In a patient who has a catastrophic illness and unexplained symptoms that could be of vascular origin, especially in the presence of chest pain, aortic dissection should always be included in the differential diagnosis.

Acute Disease↗
PubMed1993

Imaging spectrum of thrombo-occlusive vascular disease associated with antiphospholipid antibodies.

The association of antiphospholipid antibodies with unexplained thrombo-occlusive vascular disease is well known but often remains unrecognized. The most well-studied clinical manifestation is venous thrombosis, but arterial occlusive disease involving multiple sites is also well documented. Twenty-six cases of thrombo-occlusive disease were observed in 22 patients over a 3-year period. Magnetic resonance imaging and angiography were used to make the diagnoses. None of the patients who underwent angiography or venography developed thrombolytic disease related to the puncture site. This group of patients with antiphospholipid antibody syndrome had a wide distribution of arterial and venous thrombotic disease. Radiologists should consider antiphospholipid antibody syndrome in the differential diagnosis when evaluating thrombo-occlusive vascular disease that is unexpected or occurs without risk factors. Knowledge of antiphospholipid antibody status has important implications for prognosis and therapy.

Adult↗