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Biomedical subjects

J M Porter

Publications and source records attributed to J M Porter.

At least 217 records · Page 12Linked to original sources
PubMed1988

The clinical course of carotid bifurcation stenosis as determined by duplex scanning.

Two hundred three patients had at least two carotid artery duplex (DS) examinations separated by at least 6 months (mean follow-up 18 months) and their risk factors, clinical outcome, and degree of carotid artery stenosis were compared. The accuracy of DS was established at greater than 90% by blinded comparison with angiography. During the study period 138 patients (68%) had stable carotid artery stenosis and 65 patients (32%) had progression of stenosis in at least one artery. Thirty patients had new symptoms of cerebrovascular disease (19 with transient ischemic attacks and 11 with stroke) during the study. It was not possible to predict which patients would become symptomatic on the basis of risk factor analysis or analysis of severity of stable carotid stenosis. Patients with progression of carotid artery stenosis to greater than 50% diameter reduction were significantly more likely (p less than 0.0001) to have new transient ischemic attack and stroke than were those with stable carotid artery stenosis, regardless of severity.

Adult↗
PubMed1988

Blood flow in the upper limb during brachial plexus anaesthesia.

Changes in finger blood flow, arm blood flow and cardiac output were measured using electrical impedance plethysmography in 20 patients after brachial plexus anaesthesia. The anaesthetic solution used in all patients was 1% lignocaine with adrenaline 1:200,000. Significant increases in cardiac output and blood flow to the unanaesthetised arm were observed immediately after anaesthesia had become effective. A highly significant increase in the blood flow to fingers of the blocked hand was observed throughout the period of anaesthesia but there was no overall increase in the blood flow to the arm. It is suggested that the adrenaline contained in the local anaesthetic solution increased the cardiac output and caused arterial vasoconstriction at the site of injection.

Adult↗
PubMed1988

Late-onset Raynaud's syndrome: diagnostic and therapeutic considerations.

A mild form of Raynaud's syndrome probably affects a significant percentage of the general population, apparently without serious sequelae. However, the patient with episodic digital ischemia who seeks medical attention is likely to have an identifiable associated disorder and a thorough evaluation is warranted. Autoimmune connective tissue disorder and atherosclerosis are the clinical conditions most frequently associated with Raynaud's syndrome. Conservative measures should be the mainstay of therapy.

Aged↗
PubMed1988

Congenital venous valvular aplasia of the lower extremities.

A 10-year-old girl had bilateral, symmetrical swelling of the lower extremities, which had been present since the age of 1 year. Noninvasive vascular laboratory measurements of the ambulatory venous pressure, venous recovery time, and maximum venous outflow revealed profound bilateral lower extremity venous valvular incompetence. Duplex imaging of the veins of the lower extremities demonstrated no evidence of thrombosis, and no venous valves could be imaged. On phlebography, the patient was found to have no venous valves in the superficial and deep systems of the leg. We conclude that congenital absence of the venous valves of the lower extremities is almost certainly underdiagnosed and that the vascular laboratory can accurately and easily differentiate between lymphedema and venous valvular imcompetence. Such differentiation may have therapeutic implications.

Child↗
PubMed1987

Buerger's disease in the modern era.

In an effort to determine the current incidence and clinical course of Buerger's disease, we reviewed the records of over 700 patients with small artery disease who were evaluated at Oregon Health Sciences University during a 15 year period. We identified 26 patients who met rigid criteria for the diagnosis of Buerger's disease. An analysis of the management and extended follow-up of these patients has indicated that Buerger's disease, although rare, is a real clinical entity which can be diagnosed objectively. The relatively high rate of limb loss (31 percent of patients) documents the virulence of Buerger's disease involving the lower extremities. No major upper extremity amputations were required, and no patient lost further tissue after cessation of smoking. These findings and the low mortality rate in this study stand in contrast to many previous reports and may aid in establishing the current natural history of Buerger's disease in North America.

Adolescent↗
PubMed1987

Autogenous reversed vein bypass for lower extremity ischemia in patients with absent or inadequate greater saphenous vein.

This report has presented the results of 329 reversed vein bypasses performed for lower extremity ischemia over a 6 3/4 year period. One hundred eighty-nine bypasses were formed from intact ipsilateral greater saphenous veins of adequate size and length. One hundred forty bypasses were formed in patients in whom the ipsilateral greater saphenous vein was absent or of inadequate size or length to complete the bypass. The grafts in these patients were accomplished using a variety of techniques including distal graft origin, use of arm veins and lesser saphenous veins, and use of vein splicing. The patency rates of these grafts were equivalent to those achieved using adequate intact ipsilateral greater saphenous vein. In view of these results, we conclude that the absence of a greater saphenous vein does not preclude successful autogenous lower extremity vein bypass and that prosthetic bypass is rarely justified.

Femoral Artery↗
PubMed1987

Measurement of cardiac output by electrical impedance plethysmography.

There are many potential applications for cardiac output measurement in clinical and experimental medicine. The most commonly used techniques are invasive procedures, requiring cardiac or arterial catheterization, a disadvantage that has restricted their wider application. Impedance plethysmography has been developed as a non-invasive, beat-by-beat method of cardiac output measurement, which provides an estimate of stroke volume from changes in the electrical impedance of the thorax during cardiac systole. The values for cardiac output obtained by this technique have been extensively compared with values obtained by other methods, both in experimental animals and in the human subject. In the majority of studies high correlation coefficients have been obtained, although impedance plethysmography has tended to give higher absolute values than most other methods. Values for cardiac output obtained by impedance plethysmography are best assessed by comparison with a series of normal values obtained by this technique, rather than with values obtained by other methods. We discuss the results of an investigation of normal cardiac output by impedance plethysmography; theoretical objections to impedance cardiography are considered, and various methods of determining the specific resistivity of blood are reviewed.

Adolescent↗
PubMed1987

Measurement of pulsatile limb and finger blood flow by electrical impedance plethysmography: criteria for the diagnosis of abnormal flow.

The range of pulsatile arm and finger blood flow, measured by electrical impedance plethysmography, has been investigated in a hospital ward. The range of absolute blood flows, in ml min-1, was found to be too wide to be used as a standard for identifying single blood flow readings as being abnormal. A blood flow ratio was calculated by dividing the blood flow in the right forearm or middle finger by the blood flow in the left forearm or middle finger. This ratio was found to have a clearly defined range. A blood flow in a unilaterally injured or otherwise abnormal arm or finger was considered to be significantly altered if the blood flow ratio fell outside the previously defined normal range. The diagnosis of significantly altered arm and finger blood flow from abnormalities in the blood flow ratio was tested in a series of experiments, in which artificial changes in upper limb flow were created by high elevation of the right hand. The ratio was measured in 11 patients with unilateral upper limb injuries and in 3 patients who required an urgent assessment of the upper limb circulation. Abnormalities in the ratio were identified in 12 out of 18 subjects after high elevation of the hand and in 8 out of the 14 patients.

Arm↗
PubMed1987

Reversed vein bypass to infrapopliteal arteries. Modern results are superior to or equivalent to in-situ bypass for patency and for vein utilization.

In recent years many reports have attributed improved patency and improved vein utilization with lower extremity arterial bypass to infrapopliteal arteries to the use of the in-situ vein graft technique (ISVB). This report describes 110 reversed vein bypasses (RVB) to infrapopliteal arteries performed from 1980-1986. Thirty-three per cent of these patients did not have an intact ipsilateral greater saphenous vein. One hundred per cent of patients had autogenous RVB performed using a variety of techniques, including vein splicing, use of arm veins, lesser saphenous veins, branch veins, and use of graft origins distal to the common femoral artery. The life table patency figures for these grafts are 90%, 85%, and 85% at 1 year, 3 years, and 5 years, respectively. The life table limb salvage at 5 years is 93%. These figures for patency, vein utilization, and limb salvage for modern RVB to infrapopliteal arteries are clearly equal to or superior to any reported figures for ISVB. Results for RVB are greatly improved when compared with historic controls, as are results for ISVB. There is no evidence to date demonstrating superiority of one technique versus another.

Adult↗
PubMed1987

Digital ischemia as a manifestation of malignancy.

The association of malignancy with thrombotic disorders of the arterial and venous systems is well described. To date, however, there are only 23 published case reports of digital gangrene associated with malignancy. During a prospective evaluation of over 700 patients with finger ischemia, there were five patients with finger gangrene associated with malignancy. Detailed clinical and laboratory evaluation, including detailed immunologic survey and hand angiography, allowed establishment of the precise mechanisms responsible for vascular occlusions in each patient. Three mechanisms were identified: arteritis, hyperviscosity, and hypercoagulability. Digital gangrene associated with malignancy is a rare condition, the mechanism for which can be deduced by careful diagnostic evaluation.

Adult↗
PubMed1987

Upper extremity ischemia caused by small artery disease.

One hundred patients with ischemic finger ulceration had detailed prospective evaluation to determine the incidence of associated diseases, response to treatment, and natural history of the condition. A potentially serious associated disease was detected in each patient including autoimmune disease in 54%, Buerger's disease in 9%, arteriosclerosis obliterans in 9%, hypersensitivity angiitis in 22%, and miscellaneous diseases in 6%. Conservative treatment with soap and water scrubs, antibiotics, and local resection/debridement resulted in long-term healing without recurrence in 88% of patients. Most recurrences occurred in patients with autoimmune disease, usually scleroderma or CRST.

Angiography↗
PubMed1987

Alpha 2-adrenergic receptor levels in obstructive and spastic Raynaud's syndrome.

The present study examines the hypothesis that alterations in the activity of alpha 2-adrenergic receptors (A2R) may underlie the clinical vasospasm seen in patients with Raynaud's syndrome. Platelets were isolated from 13 normal subjects, from 50 patients with vasospastic Raynaud's syndrome, and from 20 patients with obstructive Raynaud's syndrome and A2R levels measured. Binding capacity as determined in femtomoles per milligram of protein (fmol/mg of protein) and affinity were measured by Scatchard plot analysis. In a separate experiment normal human platelets were incubated with either buffer, normal serum, or serum from patients with spastic Raynaud's syndrome and A2R levels were measured. A2R levels in normal subjects averaged 112 +/- 18 fmol/mg; in the patients with spastic Raynaud's syndrome, 191 +/- 14 fmol/mg, p less than 0.01; and in the patients with obstructive Raynaud's syndrome, 164 +/- 31 fmol/mg, p greater than 0.05 (ns). Of the patients with spastic Raynaud's syndrome, 26% had values that were less than the mean value of the normal subjects (69 +/- 7 fmol/mg, p less than 0.05). The A2R levels decreased after incubation with serum from patients who had spastic Raynaud's syndrome by 17.4 +/- 3.1 fmol/mg (p less than 0.05). These results indicate that most patients with vasospastic Raynaud's syndrome have increased platelet A2R levels, which may constitute a primary pathophysiologic abnormality underlying this condition. The presence of subnormal A2R levels in a portion of the patients and the finding of a decrease in measurable A2R levels after incubation in serum from patients with spastic Raynaud's syndrome suggests the possibility of receptor modulation as a mechanism for increased cellular receptor synthesis.

Blood Platelets↗
PubMed1987

The clinical course of diabetics who require emergent foot surgery because of infection or ischemia.

For the past 15 years at our institution, all acute diabetic foot problems have been treated on the vascular surgery service. The treatment approach has emphasized aggressive local foot surgery and frequent use of revascularization to avoid amputation. A total of 212 urgent or emergent foot operations were performed on 138 limbs in 114 diabetic patients for indications of infection, gangrene, or infected neurotrophic ulcers. The average number of operations per limb was 1.5 (range one to six) and per patients was 1.9 (range one to nine). Ischemia was sufficiently severe to require concurrent lower extremity revascularization in 48 limbs in 43 patients. Follow-up ranged from 1 month to 11 years (mean 3 years). Ultimately 36 major lower extremity amputations were required in 33 patients at time intervals ranging from zero to 86 months (mean 7 months) after the initial operation on the affected limb. These data indicate that an aggressive program of surgical treatment of diabetic foot problems combined with liberal use of lower extremity revascularization resulted in long-term salvage of 73% of threatened limbs in these high-risk patients. These results form the basis for our recommendation that major lower extremity amputations be considered only as a last resort in diabetic patients with limbs threatened by foot infection or localized gangrene.

Adult↗
PubMed1987

Supraceliac aortofemoral bypass.

Increasing numbers of patients with aortoiliac disease are seen with contraindications to standard infrarenal aortofemoral reconstruction. Although axillofemoral bypass is possible in these patients, the decreased patency rate associated with this operation makes alternate procedures desirable. This report details our experience with prosthetic bypass from the supraceliac aorta to the femoral arteries in seven patients with limb-threatening ischemia of the lower extremity, all of whom had undergone multiple previous aortic operations. The operations were performed through thoracoabdominal or flank incision, and the preferred graft configuration consisted of a single Dacron tube from the aorta to the left groin with a standard subcutaneous femorofemoral graft to the right groin. No surgical deaths occurred. At 3 1/2 years' mean follow-up, there has been one graft limb occlusion that resulted in amputation for an overall life table patency and limb salvage rate of 93%. We conclude that supraceliac to femoral artery bypass is a useful procedure for the treatment of patients who have had multiple previous aortic reconstructions fail.

Adult↗
PubMed1986

Extraperitoneal iliac endarterectomy in the treatment of multilevel lower extremity arterial occlusive disease.

The traditional approach to the surgical correction of lower extremity ischemia resulting from combined aortoiliac and femoropopliteal disease has consisted of aortofemoral bypass as the initial step. This operation is of considerable magnitude, mandates the use of prosthetic material, and may not adequately relieve distal ischemia. Extraperitoneal iliac endarterectomy is an operation of lesser magnitude and does not require the use of prosthetic material. When applied to selected patients with multilevel disease, it can be conveniently and expeditiously combined with distal bypass and deep femoral repair, femorofemoral bypass, or both for the simultaneous and complete correction of multilevel disease. In the past 10 years, 65 patients underwent simultaneous extraperitoneal iliac endarterectomy in combination with an outflow procedure for the correction of multilevel lower extremity arterial occlusive disease. Using a two-team approach, operative time averaged 3 hours. Operative mortality was 5 percent. The procedure was combined with femoral endarterectomy in 60 patients, with femoropopliteal-to-tibial bypass in 30 patients, and with femorofemoral bypass in 10 patients. The life table patency for iliac endarterectomy was 100 percent at 6 years, whereas patency for the associated outflow procedures was 87 percent at 6 years. These results indicate that extraperitoneal iliac endarterectomy is uniquely suited for combination with distal procedures to permit the simultaneous repair of combined aortoiliac and femoropopliteal disease in a single operation of reasonable magnitude.

Adult↗