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Biomedical subjects

M R Nehler

Publications and source records attributed to M R Nehler.

27 records · Page 2Linked to original sources
PubMed1996

Improving selection of patients with less than 60% asymptomatic internal carotid artery stenosis for follow-up carotid artery duplex scanning.

PURPOSE: The Asymptomatic Carotid Atherosclerosis Study (ACAS) indicated significant benefit from endarterectomy compared with medical therapy for patients with 60% to 99% asymptomatic internal carotid artery (ICA) stenoses. To date, optimal selection of patients for vascular laboratory follow-up to determine progression from < 60% to > or = 60% asymptomatic ICA stenosis is unknown. To determine which patients with < 60% asymptomatic ICA stenoses are at greatest risk for short-term progression to > or = 60% without symptoms, we reviewed vascular laboratory results and clinical risk factors of consecutive patients who were prospectively observed in a study of atherosclerosis progression. METHODS: Carotid duplex studies were obtained every 6 months and were reviewed for progression from < 60% to > or = 60% asymptomatic ICA stenosis by using criteria that were developed and reported by our laboratory. Clinical risk factors and velocities from initial duplex scans were analyzed for association with progression from < 60% to > or = 60% ICA stenoses without symptoms. RESULTS: Two hundred sixty-three patients (mean age, 66 years) with 434 asymptomatic < 60% ICA stenoses were prospectively observed for a mean of 20 months, with a mean of four examinations per patient. Seventeen patients (6.5%) and 18 ICAs (4%) progressed without symptoms to > or = 60% ICA stenoses at a mean of 18 months. Clinical risk factors associated with progression to > or = 60% asymptomatic ICA stenosis included elevated systolic blood pressure and decreased ankle-brachial index (p = 0.05). The mean initial ICA peak systolic velocity (PSV) in ICAs that progressed to > or = 60% asymptomatic stenoses was 180 cm/sec, compared with 104 cm/sec in asymptomatic ICAs that did not progress to > or = 60% (p = 0.0003). Thirty-one percent of asymptomatic ICAs that had initial PSVs of 175 cm/sec or greater progressed to > or = 60% stenosis, whereas only 1.8% that had initial PSVs less than 175 cm/sec progressed to > or = 60% asymptomatic stenoses (p < 0.001). The life-table-determined rate of freedom from progression to > or = 60% stenosis was 94% at 4 years for asymptomatic ICA lesions that had initial PSVs less than 175 cm/sec, compared with 14% at 3 years for lesions that had initial PSVs > or = 175 cm/sec. CONCLUSIONS: Early progression from < 60% asymptomatic ICA stenoses to > or = 60% asymptomatic ICA stenoses occurs infrequently. Patients who are at the greatest risk of early progression without symptoms to an ACAS-positive lesion can be identified from the ICA PSV at their initial duplex examination. Early vascular laboratory follow-up of asymptomatic ICA stenoses may be limited to a relatively small group.

Aged↗
PubMed1995

Do normal early color-flow duplex surveillance examination results of infrainguinal vein grafts preclude the need for late graft revision?

PURPOSE: Optimal duration of postoperative duplex surveillance of infrainguinal vein grafts is not known. Previous reports have suggested nearly all vein graft stenoses are present within the first postoperative year, and normal duplex examination results during this time eliminate the need for ongoing graft surveillance. To determine whether surveillance may be safely discontinued in patients with normal early postoperative surveillance studies, we reviewed the color-flow surveillance examinations in our patients who underwent infrainguinal reverse vein graft revisions during a 4 1/2 year period. METHODS: Clinical and vascular laboratory records were reviewed of all patients who underwent infrainguinal reverse vein bypass grafting followed by subsequent graft revision for a duplex scanning-detected abnormality at our institution between January 1990 and July 1994. RESULTS: Of 447 infrainguinal reverse vein bypasses performed, 36 (8.1%) underwent surgical revision as a result of an abnormal finding during routine duplex surveillance. The initial postoperative duplex examination was obtained within 2 weeks of graft implantation in 23 (64%) patients, between 2 weeks and 3 months in 10 (28%) patients, and between 3 and 6 months in three (8%) patients. Duplex abnormalities prompting revision included 11 (31%) grafts with a mid-graft peak systolic velocity (PSV) < or = 45 cm/sec, 23 (64%) grafts with a focal PSV > or = 200 cm/sec, one graft with a PSV > or = 150 cm/sec but < 200 cm/sec, and one thought to be occluded by duplex but found to be patent by angiography. Abnormal duplex findings were initially detected within 2 weeks of graft implantation in five (14%) patients, between 2 weeks and 3 months in eight (22%) patients, from 3 to 6 months in 12 (33%) patients, from 6 to 12 months in six (17%) patients, and > 1 year in five (14%) patients. In only 25% of cases were mid-graft PSVs < or = 45 cm/sec or focal velocities > or = 200 cm/sec identified on the initial examination; 75% were found during subsequent surveillance. CONCLUSIONS: Although most reverse vein graft abnormalities detected by duplex surveillance and prompting graft revision appear within the first postoperative year, many are not detected on the initial examination. In our recent experience 31% of duplex abnormalities leading to vein graft revision were first detected more than 6 months after operation. Discontinuation of graft surveillance based on normal early findings will result in thrombosis of some vein grafts that may otherwise be salvaged.

Adult↗
PubMed1994

Surgical treatment of threatened reversed infrainguinal vein grafts.

PURPOSE: Current information concerning the results of surgical revision of threatened infrainguinal vein grafts is largely limited to in situ conduits. Infrainguinal grafts may be threatened by intrinsic graft lesions or significant stenosis in the adjacent inflow or outflow arteries. To assess the results of operative revision of infrainguinal reversed vein grafts, we reviewed our experience with surgical revision of threatened infrainguinal reversed vein grafts identified through a program of postoperative clinical and vascular laboratory graft surveillance. METHODS: All patients who underwent surgical revision of a threatened but patent infrainguinal reversed vein graft from January 1987 through April 1993 were identified through review of our vascular registry. Data were analyzed for type of vein used, date of original reversed vein graft, clinical and vascular laboratory findings leading to reversed vein graft revision, results of preoperative angiography, patient risk factors, operative techniques and complications, and long-term assisted primary graft patency and limb salvage. RESULTS: Ninety-six patients with 100 infrainguinal reversed vein grafts (69) femoral-popliteal, 31 femoral-tibial) underwent 117 surgical vein graft revisions or inflow procedures during the study period. Eighty-one percent of the original reversed vein grafts consisted of a single segment of greater saphenous vein. All revised grafts had at least a 50% stenosis in the graft itself or the proximal or distal artery. A single revision was performed in 85 grafts, two revisions in 13 grafts, and three revisions in two grafts. There were nine (8%) isolated inflow procedures, eight (7%) vein patch angioplasties, 62 (53%) interposition vein grafts, and 29 (25%) vein graft extensions to a new distal anastomotic site. The remaining nine (8%) procedures consisted of combinations of the above. Median time to primary graft revision after initial graft implantation was 15 months (range 2 days to 316 months). Mean time to secondary revision after primary revision was 21 months. Operative mortality was 0.9%. Cumulative assisted primary patency of the original grafts revised for stenotic lesions was 99%, 96%, and 92% at 1, 3, and 5 years, respectively. Limb salvage was 99%, 97%, and 97% at 1, 3, and 5 years, respectively. CONCLUSIONS: Although surgical revision of reversed vein graft requires much use of alternative vein sources, these procedures can be performed with minimum mortality and provide excellent assisted primary graft patency and limb salvage.

Adult↗
PubMed1993

Anticoagulation followed by elective carotid surgery in patients with repetitive transient ischemic attacks and high-grade carotid stenosis.

OBJECTIVE: To evaluate the results of preoperative heparin therapy followed by carotid surgery for patients with repetitive transient ischemic attacks (TIAs) and high-grade carotid stenoses. DESIGN: A 4-year prospective study. SETTING: Oregon Health Science University Hospital and Portland (Ore) Veterans Affairs Hospital. PATIENTS: Twenty-nine consecutive patients with repetitive TIAs referable to 30 high-grade (> or = 70%) ipsilateral carotid stenoses were treated with short-term heparin anticoagulation, followed by cerebral angiography, routine preoperative evaluation, and subsequent carotid reconstruction. INTERVENTIONS: Heparin sodium anticoagulation was maintained for a mean of 5 days. Surgical management consisted of 24 standard endarterectomies, five bypasses to the internal carotid artery, and one external carotid endarterectomy. MAIN OUTCOME MEASURES: Primary outcome variables included perioperative hemorrhage, thrombocytopenia, stroke, and death. Secondary outcome variables included carotid occlusion and recurrent TIAs with heparin therapy. RESULTS: One symptomatic common carotid occlusion and one asymptomatic internal carotid occlusion occurred during preoperative heparin therapy. Thirteen patients had additional sporadic TIAs while receiving heparin. There were no preoperative cerebral infarcts, thrombocytopenia, or clinical bleeding associated with heparin therapy. There was one postoperative stroke and one death due to myocardial infarction. CONCLUSION: When necessary, heparin anticoagulation and delayed carotid reconstruction would appear to be an acceptable alternative to emergency carotid surgery in patients with high-grade carotid stenosis and acute repetitive TIAs.

Aged↗
PubMed1993

Perimalleolar subcutaneous tissue pressure effects of elastic compression stockings.

PURPOSE: We hypothesized that the clinical benefit of elastic compression stockings (ECS) is at least in part due to an increase in subcutaneous pressure that may promote resorption of extracellular fluids, providing more efficient diffusion of oxygen and nutrients from the microcirculation to the skin and subcutaneous tissues. METHODS: To test this hypothesis we designed and standardized a device for measuring subcutaneous pressure in patients. We then measured the supine perimalleolar subcutaneous pressure from a single limb in four groups: group 1 consisted of control subjects (n = 8); group 2 consisted of patients with varicose veins and superficial venous insufficiency without lipodermatosclerosis or edema (n = 5); group 3 consisted of patients with deep venous insufficiency and lipodermatosclerosis but without edema (n = 8); and group 4 consisted of patients with deep venous insufficiency, lipodermatosclerosis, and clinically evident edema (n = 8). Measurements were made at baseline and after application of 20 to 30 mm Hg and 30 to 40 mm Hg ECS. RESULTS: There was no significant difference in the baseline subcutaneous pressure between the three groups without clinical edema (p > 0.05). Baseline perimalleolar pressure was elevated, however, in group 4 patients compared with groups 1, 2, and 3 (p < 0.05). All three groups with chronic venous insufficiency (CVI) (groups 2, 3, 4) demonstrated increases in subcutaneous pressure with application of ECS, which was statistically significant in groups 3 and 4. There was no difference between the increase in perimalleolar subcutaneous pressure induced by 20 to 30 mm Hg or 30 to 40 mm Hg ECS in groups 3 and 4. CONCLUSIONS: Patients with CVI and edema have significant elevations in supine resting perimalleolar subcutaneous pressure compared with control subjects and patients with CVI without edema. Twenty to 30 mm Hg and 30 to 40 mm Hg ECS increased measured perimalleolar subcutaneous pressure in patients with CVI with and without clinical edema but not in control patients. These results suggest the mechanism of benefit of ECS in patients with CVI is due at least in part to an increase in subcutaneous pressure that may act to promote more efficient absorption of perimalleolar extracellular fluid.

Adult↗
PubMed1993

Arteritis.

Explore the source record for details and available documents.

Arteritis↗
PubMed1993

Surgery for chronic lower extremity ischemia in patients eighty or more years of age: operative results and assessment of postoperative independence.

PURPOSE: Revascularization for chronic lower extremity ischemia (CLEI) in patients 80 or more years of age is controversial. High operative mortality, short remaining life span, and nonambulatory nursing home existence are cited as frequent outcomes in this patient group. Despite these considerations we have maintained an aggressive policy of lower extremity revascularization in functional and potentially functional patients 80 or more years of age with limb-threatening ischemia or claudication sufficient to threaten their independence. METHODS: The records of all patients 80 or more years of age who underwent lower extremity revascularization for CLEI from 1981 through 1991 were reviewed. Patients were evaluated for surgical indication, perioperative mortality, late survival, graft patency, and limb salvage. In addition, the patient's preoperative and postoperative independence determined by living situation (home versus nursing home) and ambulatory status were examined. RESULTS: During the period reviewed 88 patients 80 or more years of age underwent 95 arterial reconstructions for CLEI; 95% for limb salvage and 5% for short-distance claudication. There were 81 (85%) infrainguinal bypasses and 14 (15%) extra-anatomic bypasses, 5 of which also included a simultaneously placed infrainguinal bypass. The perioperative mortality rate was 6%. Mean hospitalization was 18 days (range 6 to 62). The 1- and 3-year primary graft patency rates were 88% and 66%, limb salvage rates 94% and 91%, and patient survival rates 73% and 51%, respectively. One year after operation 88% of patients were ambulatory, 85% were living at home, and 80% were both living at home and ambulatory. At 3 years these results were 86%, 76%, and 71%, respectively. Of the patients living at home and ambulatory before operation, 100% and 84% of survivors were still living at home and ambulatory 1 and 3 years after operation. Of patients living at home who had late graft occlusions, 67% required amputation and subsequent nursing home placement. CONCLUSION: Although survival in this group is predictably lower than that of age-matched control subjects, octogenarians have satisfactory 1- and 3-year graft patency, limb salvage, and functional results. Revascularization for CLEI in patients 80 or more years of age is appropriate and results in maintenance of independent living in a large majority.

Activities of Daily Living↗
PubMed1992

Upper extremity arterial bypass distal to the wrist.

Seventeen arterial bypass procedures distal to the wrist have been performed in 13 men and two women at the Oregon Health Sciences University during the past 9 years. Ten patients had traumatic true or false aneurysms of the ulnar artery with digital embolization. Five patients with end-stage renal disease had severe hand and finger ischemia manifested by rest pain or digital ulceration resulting from widespread forearm and hand arterial occlusions. Patients with aneurysms of the ulnar artery underwent excision and reversed autogenous vein grafting (n = 11) from the distal ulnar artery in the forearm to the superficial palmar arch. All the patients with end-stage renal disease had severe occlusive disease of the forearm and hand arteries and underwent a variety of procedures including radial-radial bypass (n = 2), ulnar-ulnar bypass (n = 2), radial-radial bypass with takedown of a Brescia-Cimino fistula (n = 1), and brachial-radial bypass (n = 1). High-quality upper extremity and magnification hand arteriography was essential for operative planning and was available on all patients. Distal saphenous vein from the ankle or foot was the graft source in 16 procedures and basilic vein the source in one procedure. All operations were performed with headlight illumination, optical loupes, fine sutures, and microvascular instruments. There were no operative deaths or major complications. The mean follow-up period was 14 months. Of the 17 grafts, 16 remained patent by clinical and vascular lab criteria. The single occlusion occurred in an ulnar aneurysm bypass and was accompanied only by mild intolerance to cold.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗