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J M Porter

Publications and source records attributed to J M Porter.

At least 145 records · Page 8Linked to original sources
PubMed1994

Cooling augments human saphenous vein reactivity to electrical stimulation.

Human saphenous veins were obtained at operation and assayed immediately (n = 10). The veins were cut into rings, suspended in organ chambers, and connected to force transducers for recording of isometric tension. One ring served as control; others were treated with either the alpha 1-adrenoceptor antagonist prazosin (Pz, 3 x 10(-7) M) or the alpha 2-adrenoceptor antagonist rauwolscine (Rw1, 10(-7) M). Cooling from 37 degrees to 24 degrees C had no significant effect on the resting tone of quiescent rings. Electrical stimulation (0.2-16 Hz) caused frequency-dependent contractions in control vessels. The contractions were inhibited by Pz (p < 0.001) and by Rw (p < 0.001). In control rings, cooling potentiated contractions evoked at all frequencies. Similar augmentations were induced by cooling in rings treated with the alpha 1-antagonist Pz. In contrast, rings treated with Rw before being electrically stimulated showed no significant change in contractile force when cooled. The data indicate that in the human saphenous vein, both alpha 1- and alpha 2-adrenoceptors are innervated, contributing to contractile response evoked by neuronal excitation. Cold augments saphenous vein reactivity to endogenously released norepinephrine (NE) by an apparent increase in the responsiveness of alpha 2-adrenoceptors to agonists. This relationship between temperature and adrenoceptor responsiveness is consistent with the hypothesized role of alpha 2-adrenoceptors in cold-induced vasospasm.

Cold Temperature↗
PubMed1994

Hemodynamic assessment of combined aortoiliac/femoropopliteal occlusive disease and selection of single or multilevel revascularization.

Approximately 25% of patients with multilevel arterial occlusive disease will require both inflow and outflow revascularization in order to successfully resolve their symptoms of lower limb ischemia. The preoperative selection of patients for multilevel concurrent arterial reconstruction is guided by symptoms, information from the noninvasive vascular laboratory, the predicted postoperative ABI, and detailed multiview angiography including pull-back intra-arterial pressure measurements. Properly selected patients will benefit from a carefully planned and expeditiously performed simultaneous revascularization. Current results indicate no significant increase in operative morbidity or mortality rates and excellent graft patency rates with these combined procedures.

Aortic Diseases↗
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

Excision of benign pigmented skin tumours by deep shaving.

Benign pigmented skin tumours are frequently removed by shave excision. There is little information as to how often the method achieves a complete excision of the lesion and how often the full thickness of the dermis is removed. 43 benign pigmented skin tumours, on the trunk and proximal parts of the limbs, were removed by deep shaving and the shaved areas were then removed by elliptical excision. The shave excision achieved complete tumour removal in 72% of the lesions and did not divide the dermis to fat junction in 63%. Both objectives were achieved in 46%. Shave excision of these lesions may be preferable to elliptical excision in sites where the incidence of hypertrophic scarring is high, as preservation of some thickness of the dermis may result in a more acceptable scar.

Adolescent↗
PubMed1993

Noninvasive localization of arterial occlusive disease: a comparison of segmental Doppler pressures and arterial duplex mapping.

PURPOSE: The purpose of this study was to compare the abilities of arterial duplex mapping and segmental Doppler pressures to noninvasively localize hemodynamically significant lower extremity arterial occlusive disease. METHODS: After angiographic controls were instituted, arterial duplex mapping and segmental Doppler pressures were blindly compared for their ability to localize a high-grade (50% to 100%) stenosis to the iliac or common femoral arteries, the superficial femoral artery, or the popliteal artery in 151 lower extremities from 79 patients. RESULTS: Rates of sensitivity and specificity of arterial duplex mapping for identifying a high-grade stenosis at the three arterial levels were 88% and 97%, 95% and 100%, and 78% and 99%, respectively. Those for segmental Doppler pressures were 59% and 86%, 73% and 80%, and 48% and 53%, respectively. There was complete agreement between arterial duplex mapping and angiography in 82% of the limbs studied and between segmental pressures and angiography in 34% of the limbs (p < 0.0001). The presence of diabetes, kidney failure, or previous vascular surgery in the limb studied did not affect the accuracy of either test. CONCLUSION: Arterial duplex mapping is far superior to segmental Doppler pressures for localization of high-grade angiographic lesions from the iliac to the popliteal arteries.

Aged↗
PubMed1993

Mesenteric duplex scanning: a blinded prospective study.

PURPOSE: Based on retrospective comparisons of duplex scanning with arteriography of the celiac (CA) and superior mesenteric (SMA) arteries in 34 patients, we previously suggested that an SMA peak systolic velocity of 275 cm/sec or greater or no flow signal and a CA PSV of 200 cm/sec or greater or no flow signal were reliable indicators of a 70% or greater angiographic stenosis of the SMA and CA, respectively. We now report the results of a blinded, prospective study in a larger patient group designed to determine the ability of mesenteric duplex scanning to visualize the CA and SMA and to validate our proposed duplex criteria for splanchnic artery stenosis. METHODS: During an 18-month period 100 patients admitted to our vascular surgery service for aortography underwent routine mesenteric artery duplex scanning and lateral abdominal aortography regardless of abdominal symptoms. The lateral aortograms were evaluated to determine the presence or absence of a 70% or greater stenosis in the CA or SMA. Duplex-determined peak systolic velocities from the CA and SMA were recorded without knowledge of the angiographic results. RESULTS: Aortography satisfactorily visualized 100% of the CAs and 99% of the SMAs. Of these, 93% of the SMAs and 83% of the CAs were visualized by duplex. According to the above criteria, duplex sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy for detection of a 70% or greater SMA stenosis were 92%, 96%, 80%, 99%, and 96% and for a 70% or greater CA stenosis 87%, 80%, 63%, 94%, and 82%. CONCLUSIONS: Mesenteric duplex scanning is feasible in the majority of patients. Prospective evaluation of duplex diagnostic criteria for 70% or greater stenosis indicates that mesenteric duplex scanning is sufficiently accurate to be clinically useful as a screening examination to detect SMA and CA stenosis.

Adult↗
PubMed1993

Human saphenous vein grafts explanted from the arterial circulation demonstrate altered smooth-muscle and endothelial responses.

PURPOSE: Animal models have been used to assess the function of vascular smooth muscle and endothelium of veins grafted into arterial circulation. The primary model consists of grafting the external jugular vein into the carotid artery of the rabbit. These studies suggest a selective increase in the responsiveness of the grafted veins to serotonin. However, in both human cardiac and peripheral vascular operations, the saphenous, not the jugular, is the vein most frequently used. Thus the propriety of the rabbit model is unknown. METHODS: Human saphenous veins and vein grafts were obtained from patients undergoing leg vein bypass graft revisions (n = 8). The reversed vein grafts were placed into arterial circulation for periods ranging from 4 to 26 months before removal (mean 16 months). All vessels were immediately cut into rings and suspended in organ chambers for recording isometric contractions to norepinephrine and serotonin. RESULTS: The maximal contractions elicited by both norepinephrine and serotonin were reduced in human vein grafts in comparison to the results in human saphenous vein (maximal response to norepinephrine 1.42 +/- 0.34 gm [vein graft] vs 4.59 +/- 1.13 gm [saphenous vein], p = 0.031; maximal response to serotonin 2.68 +/- 0.58 gm [vein graft] vs 4.72 +/- 1.11 gm [saphenous vein], p = 0.042). Human vein grafts were less responsive to norepinephrine than was saphenous vein (negative log of concentration that caused 50% of the maximal response -5.91 +/- 0.10 and -6.84 +/- 0.22, respectively; p < 0.009). After precontraction with norepinephrine (to 30% of the maximal response), saphenous vein, but not vein grafts, demonstrated endothelium-dependent relaxation to acetylcholine (maximum relaxation 27.4% +/- 6.8%; p = 0.001). CONCLUSIONS: Human saphenous veins grafted into arterial circulation exhibit loss of endothelium-dependent relaxation to acetylcholine and diminished contractions to agonists (norepinephrine and serotonin). In contrast to rabbit data, serotonin elicits dose-dependent contractions in both human saphenous vein and human vein grafts. Since the vascular wall contractility varies widely across species, the relevance of rabbit vein graft data to human bypass grafts is uncertain.

Acetylcholine↗
PubMed1993

Correlation of North American Symptomatic Carotid Endarterectomy Trial (NASCET) angiographic definition of 70% to 99% internal carotid artery stenosis with duplex scanning.

PURPOSE: The North American Symptomatic Carotid Endarterectomy Trial (NASCET) has thus far demonstrated conclusive benefit for carotid endarterectomy for patients with symptomatic 70% to 99% internal carotid artery (ICA) stenosis. In the NASCET, ICA stenosis was classified angiographically: % ICA stenosis = (1 - [narrowest ICA diameter/diameter normal distal cervical ICA]) x 100%. However, widely used duplex scan criteria for ICA stenosis correlate with different angiographic categories of high-grade stenosis (50% to 79%, > 80%) and were developed on the basis of estimated bulb diameter. We therefore blindly evaluated with separate observers carotid angiograms from 100 patients who also underwent carotid duplex scanning in our vascular laboratory. METHODS: "Angiographic stenosis" was calculated as in NASCET. Duplex scan measurements of ICA peak systolic velocity (PSV), ICA end-diastolic velocity, and the ratio of ICA PSV to common carotid artery (CCA) PSV were analyzed for sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy to identify a 70% to 99% ICA stenosis. RESULTS: Analysis of the data revealed that an ICA PSV/CCA PSV ratio of 4.0 provided the best combination of sensitivity (91%), specificity (87%), positive predictive value (76%), negative predictive value (96%), and overall accuracy (88%) for detection of a 70% to 99% stenosis. CONCLUSION: We conclude duplex scan determination of 70% to 99% stenosis as defined in the NASCET requires the adoption of duplex criteria modified from those in current use in most vascular laboratories.

Angiography, Digital Subtraction↗
PubMed1993

Outcome of infrainguinal arterial reconstruction in women.

PURPOSE: The outcome of leg bypass in women is unknown. To date, most series of lower extremity bypass have included few women, and the results in women compared with those in men have not been reported. The experience with infrainguinal arterial reconstruction in women treated at the Oregon Health Sciences University has been greater than previously reported. We have reviewed our recent experience with lower extremity bypass to determine whether results in women differ significantly from those in men. METHODS: In the past 11 years we have performed 823 infrainguinal arterial reconstructions for lower extremity ischemia in 585 patients, of which 357 procedures were performed in women and 466 procedures were performed in men. The mean ages were 65 years for men and 68 years for women. Diabetes was present in 59% of the men and 48% of the women. Among men, 84% had a history of tobacco use compared with 66% of the women. Bypasses in men were performed for limb salvage in 73%, claudication in 22%, and a failing bypass graft in 5% of cases. Bypasses in women were performed for limb salvage in 79%, claudication in 15%, and a failing graft in 6% of cases. Previous revascularizations had been performed in 63% of the men and 71% of the women. Autogenous vein was used in 97% of the bypasses in men and 96% of bypasses in women. Graft distribution among infrainguinal arterial target sites was similar between the groups. Bypasses in men were femoral to above-knee popliteal in 11%, femoral to below-knee popliteal in 40%, femoral to tibial in 38%, popliteal to tibial in 10%, and tibial to tibial in 1% of cases. Bypasses in women were femoral to above-knee popliteal in 14%, femoral to below-knee popliteal in 43%, femoral to tibial in 33%, popliteal to tibial in 9%, and tibial to tibial in 1% of cases. RESULTS: Perioperative 30-day mortality rates were 3.7% overall, 4.3% in men, and 2.9% in women. Long-term survival at 1, 3, and 5 years in men was 80%, 59%, and 44%, respectively. Long-term survival at 1, 3, and 5 years in women was 83%, 69%, and 44%, respectively. Life-table primary patency rates at 1, 3, and 5 years were 86%, 77%, and 71% for men and 87%, 74%, and 67% for women. Limb-salvage results at 1 and 5 years were 93% and 91% for men and 96% and 96% for women. CONCLUSIONS: These results indicate that long-term graft patency and limb salvage results in women are identical to those obtained in men in this experience with autogenous vein. Infrainguinal arterial reconstruction can be performed in women with mortality rates similar to those of men. In this series long-term survival was similar for both men and women.

Adolescent↗
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

Visceral injury.

Trauma is a major health and social problem. It is the leading cause of death for those under age 45, and is a major expense to society, in terms of direct medical expense and lost wages. Visceral injury continues to be a major cause of morbidity and mortality in the overall trauma picture. This article reviews the significant developments in the diagnosis and management in specific areas of visceral injury.

Abdominal Injuries↗
PubMed1993

Arteritis.

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Arteritis↗
PubMed1993

An audit of peripheral nerve blocks for hand surgery.

A prospective audit of 140 median, radial and ulnar blocks, given for 70 hand operations is described. The surgery was completed successfully in every patient. A further injection of local anaesthetic was required in 13 operations. Four patients experienced severe tourniquet pain. The results of the audit have shown that if a careful technique is used, a wide range of minor hand operations can be performed under regional nerve block.

Adolescent↗