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Biomedical subjects

R N Baird

Publications and source records attributed to R N Baird.

At least 127 records · Page 7Linked to original sources
PubMed1987

The role of balloon angioplasty in the management of lower limb ischaemia.

Three hundred and twenty-three angioplasties (159 iliac; 164 femoro-popliteal) were performed for lower limb ischaemia on 253 consecutive patients from 1980-86. The mean resting ankle/brachial pressure index (ABPI) was increased at one month in open angioplasties as follows: Femoro-popliteal 0.56-0.82; iliac with open superficial femoral artery (SFA) 0.7-0.95; iliac with occluded SFA 0.52-0.63. Successful angioplasty virtually abolished the post-exercise fall in ABPI except for patients having iliac dilations when multisegment disease was present. At 5 years, cumulative patency was 72% for iliac angioplasty and 53% for femoro-popliteal angioplasty. The results of angioplasty were compared with operative arterial reconstructions during 1985. Eighty-eight (91%) of 96 surgical bypasses were alive and patent at hospital discharge and 44 (71%) of 62 angioplasties were patent at 1 month. There were many fewer complications with angioplasty which involved a much shorter hospital stay (2 days vs 16 days).

Angioplasty, Balloon↗
PubMed1987

Duplex scanning and plaque histology in cerebral ischaemia.

Twenty-seven patients undergoing carotid endarterectomy (21 M, 6 F), with a mean age of 62 years, were studied by carotid ultrasound imaging, angiography, and histological examination of endarterectomy specimens, including Perl's stain to detect haemorrhage more than a week old. Haemorrhage into a plaque was seen histologically in 21 patients (78%), compared with 19 (70%) diagnosed preoperatively as echolucent heterogeneous plaques on ultrasound imaging. The remainder were echogenic homogeneous, fibrous plaques. In only one case was the nature of the plaque diagnosed by contrast arteriography. Excised endarterectomy specimens were inspected independently of the ultrasound assessment to determine whether the site of haemorrhage communicated with the base of an atherosclerotic ulcer. Communicating haemorrhages were present in 9 of 11 with episodic symptoms and non-communicating haemorrhages in 7 of 10 patients with a single cerebrovascular event. Perl's stain showed recent haemorrhage in 7 of 11 patients with multiple symptoms, and old haemorrhage in 9 of 10 patients with a single event. These findings suggest that ultrasonically heterogeneous communicating carotid plaques are symptomatically more active than homogeneous non-communicating plaques.

Adult↗
PubMed1986

Haemodynamics of the interposition vein cuff.

It has been suggested that the use of an interposition vein cuff for anastomosing PTFE grafts to small calibre arteries confers a haemodynamic advantage. Pulsatile blood flow through a standard anastomosis was compared, in vitro, to that incorporating a vein cuff. 6 mm PTFE was anastomosed end-to-side to 10 pairs of cadaver internal mammary arteries matched for length and internal diameter (median 1.8 mm, range 1.6-2.4). Blood flow was significantly higher through the vein cuff anastomosis than the standard anastomosis (comparison of regression analysis, P less than 0.001) when the arterial diameter was less than 2.0 mm (five pairs). These results suggest that the vein cuff does confer a significant haemodynamic advantage when PTFE is anastomosed to arteries less than 2.0 mm diameter and this may be because the compliant vein cuff allows more distension of the anastomosis thus reducing anastomotic resistance.

Bioprosthesis↗
PubMed1986

Secondary aorto-enteric fistulae: towards a more conservative approach.

Eight cases of secondary aorto-enteric fistulae are presented occurring 9 months to 10 years after aortic Dacron grafting. In four patients there was a simple fistula between the anastomosis and the adherent duodenum, three patients had clinically infected grafts and one had a false aneurysm that had ruptured into the bowel. The four patients with a simple fistula had direct suture repair of the defect. One developed a recurrent fistula at 2 months and was successfully repaired again by direct suture. All four patients remain well at a follow-up of 1-5 years. The other four patients had the grafts excised, with local regrafting in two cases, both patients remaining well at follow-up. One patient had an axillo-bifemoral graft, but died at 30 days of overwhelming sepsis. The final patient, a girl with diffuse aneurysmal disease, had the aortic stump oversewn but no reconstruction. She died at 9 months of aortic stump disruption. These results suggest that a more conservative approach to the operative correction of secondary fistulae should be used wherever possible.

Adolescent↗
PubMed1986

Angiography in transient cerebral ischaemia using three views of the carotid bifurcation.

A prospective study was made of 135 patients having cerebral angiography for suspected carotid atheroma. The aim was to assess the value of a technique in which selective injections were used to show the origins of the vessels from the aortic arch and three views were taken of each of the carotid bifurcations. Disease was frequently asymmetrical and was shown in only one of the three views of the carotid bifurcation in 44% of 181 patent atheromatous internal carotid arteries. Atheroma was seen on a single view significantly more often (p less than 0.01) than was complicated atheroma, indicating that the technique was showing more early lesions than would be seen with fewer views of the region. Disease was not shown significantly more often in any one particular view, so that all three are essential to examine the bifurcation completely.

Adult↗
PubMed1986

A comparison of the costs of vascular surgery and balloon dilatation in lower limb ischaemic disease.

The length of stay in hospital was recorded for 24 patients admitted for investigation and treatment of vascular disease of the lower limb and a detailed analysis of the costs incurred was made for 10 patients. It was found that the mean cost of angiography and surgery was pounds 1577 and of angiography and dilatation, pounds 301. The major factor in the cost difference was the shorter hospital stay for dilatation, with lesser factors being the use of fewer staff and the avoidance of general anaesthesia.

Angiography↗
PubMed1986

The effects of introducing balloon dilatation into vascular surgical practice.

The numbers of angiograms, balloon dilatations, reconstructive operations and amputations carried out annually over a 5-year period following the introduction of balloon dilatation have been counted and the change in estimated costs calculated. Over the 5-year period the numbers of angiograms and reconstructive operations carried out have doubled and the number of amputations has fallen from 52 in the first year to 39 in the fifth year. The number of dilatations has increased from six in five patients in the first year to 97 in 75 patients in the fifth year. The cost of investigation and treatment has doubled but since more patients are being treated effectively, the mean cost per patient treated has fallen from pounds 1855 to pounds 1277. The introduction of balloon dilatation into vascular practice causes patients to be investigated earlier in the progress of their disease and enables more patients to be treated effectively with greater cost-efficiency, but does not reduce the overall cost of investigation and treatment of ischaemic disease of the lower limb.

Angiography↗
PubMed1986

Does the in situ technique for autologous vein femoropopliteal bypass offer any hemodynamic advantage?

The improved patency rates that have been claimed for in situ femoropopliteal vein bypass have been attributed to improved hemodynamics because of the natural taper of the vein and maintenance of wall compliance because of preservation of the nutrient vasa vasorum. Blood flow in 31 in situ and 21 reversed vein grafts was measured noninvasively with a duplex ultrasound scanner at a median of 6 months after operation. There was no significant difference in the resting or hyperemic flows between the two groups (p much greater than 0.1). The compliance of 15 undisturbed and 15 fully mobilized in situ vein grafts was measured noninvasively by Doppler ultrasonography immediately after operation and at 3 months. There was a significant fall in compliance in both groups (p less than 0.001) but no significant difference between them (p much greater than 0.1). We have been unable to demonstrate any significant hemodynamic advantage with the in situ technique but believe that its use is still justified because of technically easier anastomoses and an improved utilization rate. Preservation of the vasa vasorum does not maintain wall compliance and complete mobilization of the vein relieves any uneven tension and ensures that all venous tributaries are ligated, removing the risk of arteriovenous fistulas.

Compliance↗
PubMed1985

Detection of early arterial disease: a study using Doppler waveform analysis.

Laplace transform analysis of arterial Doppler waveforms was examined for its potential in identifying subjects with early, pre-symptomatic arterial disease. Ninety men, aged 45 to 62, and with no history of cardiovascular disease, were selected from a population of 2300 involved in a longitudinal study of risk factors for cardiovascular disease. Forty-nine were selected on the basis of high values of Laplace delta, omega o, or both, and 41 were selected with "normal" values. Three years after initial screening examination, each was examined clinically and by exercise testing for evidence of arterial disease, and the waveform recordings were repeated. In the group with high waveform analysis values initially, 11 of 49 (22%) were found to have signs of arterial disease 3 years later, while among those with lower values only 2 of 41 (5%) had evidence of disease (p less than 0.05). Although variability of results obviates their use in monitoring the progress of individual subjects, this study supports the potential of Doppler waveform analysis for identifying a group of subjects with a high incidence of early arterial disease.

Arteriosclerosis↗
PubMed1984

The clinician and the vascular laboratory in the diagnosis of aortoiliac stenosis.

Two hundred and twenty-one lower limbs in 116 arteriopaths were examined for evidence of aortoiliac stenosis, by analyses of common femoral artery Doppler waveforms for pulsatility index (PI) Laplace delta, and principal components, pulse volume recordings (PVR) and thigh pressure measurements. Clinical assessment of the aortoiliac segment was also recorded in 124 limbs. The accuracy of prediction of aortoiliac stenosis, measured on biprojectional arteriograms, was calculated for the different methods, using multiple regression analysis. Considering all grades of stenosis together, clinical judgement was the best predictor of severity (R2 - the correlation coefficient squared = 0.66): addition of non-invasive tests increased the accuracy of prediction to R2 = 0.70. For stenoses greater than 50 per cent PVR amplitude was the best non-invasive test (R2 = 0.39), but was no better than clinical assessment (R2 = 0.40). However, for stenoses less than 50 per cent clinical judgement was poor (R2 = 0.13), and derived most benefit from addition of Laplace delta (R2 = 0.20) or PVR upstroke time (R2 = 0.26). In addition, common femoral PI and Laplace delta were compared in the arteriopaths, and in 146 limbs of normal control subjects, by calculation of sensitivity and specificity. PI was superior to Laplace delta for detecting severe stenoses and occlusions, but Laplace delta was more accurate in the detection of lesser degrees of disease. These results suggest that conventional clinical assessment is the best method for detecting aortoiliac stenoses greater than 50 per cent, but for less severe disease addition of vascular laboratory tests is helpful - especially PVR and Laplace waveform analysis.

Adult↗
PubMed1984

Prostaglandin E1 in severe lower limb ischaemia: a double-blind controlled trial.

Thirty patients with ischaemic ulceration or rest pain due to lower limb atherosclerosis were treated with intravenous prostaglandin E1 (PGE1) or placebo in a prospective double-blind controlled trial. There was no significant improvement of rest pain, nor was PGE1 effective in promoting ulcer healing. This study provides no support for the use of intravenous PGE1 in the treatment of end-stage lower limb atherosclerotic disease.

Adult↗
PubMed1984

Ventilatory effects of pre- and postoperative diamorphine. A comparison of extradural with intramuscular administration.

Twenty-two patients were studied before and after major abdominal vascular surgery to determine the effect on ventilation of 5 mg diamorphine given either extradurally or intramuscularly. Diamorphine depressed ventilation maximally at 30 minutes when given by either route. Before operation resting ventilation was reduced by 33% after extradural and 17% after intramuscular diamorphine; PaCO2 increased by an average of 0.5 kPa (either route); ventilation at 7.3 kPa PaCO2 was reduced 40% after extradural and 33% after intramuscular diamorphine. After operation the effect of diamorphine on ventilation was qualitatively similar but resting baseline ventilation was increased from 9.4 to 10.9 litres/minute. The highest individual PaCO2 values were found during the pre-operative study: 6.5 kPa after extradural diamorphine, 6.4 kPa after intramuscular diamorphine. Pain relief was unsatisfactory after intramuscular diamorphine. Four out of six patients requested further analgesia by 3 hours after administration. No patient who received extradural diamorphine required further analgesia for at least 6 hours.

Adult↗
PubMed1983

Carotid murmurs.

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Adult↗
PubMed1983

Percutaneous transluminal angioplasty for lower limb ischaemia.

Forty successful percutaneous transluminal angioplasties (PTA) were performed in the iliac and femoropopliteal segments of 33 patients with lower limb ischaemia. There was immediate symptomatic relief in 37 limbs (92 per cent) although 7 relapsed and 5 patients required reconstructive arterial surgery within a month of PTA. Objective testing showed that the longer term relapse rate (median follow-up 12 months) was low (10 per cent). Despite a significant incidence of early complications and relapse, PTA provided a good long term result in the majority of patients treated.

Adult↗
PubMed1983

Arterial injuries in two Bristol hospitals from 1974 to 1980.

Fifty-eight patients with 63 peripheral arterial injuries coming to the Bristol Royal Infirmary and Frenchay Hospital, Bristol over a six-year period from 1974-1980 were studied. The majority followed road traffic accidents, and over 70 per cent occurred in teenagers and young adults. Arterial reconstructions were undertaken in 51 cases (81 per cent) with concomitant fasciotomy in 3. Pulse volume recordings and on table arteriograms were used to detect and correct 2 reconstructions which were initially less than ideal. Forty-eight of 51 reconstructions were patent at follow up.

Accidents, Traffic↗
PubMed1983

Vasectomy and atherosclerosis: an association in man?

We have investigated the distensibility of the lower limb arteries by an ultrasonic technique following vasectomy. Vasectomy accelerates the development of atherosclerosis in animals and this has been attributed to an immunological mechanism. Immunological changes are common in men following this operation, but epidemiological surveys have failed to reveal evidence of an increase in arterial disease. We have studied distensibility at the posterior tibial arteries by Laplace transform analysis of Doppler waveforms in 49 vasectomised men and 33 controls. Statistical analysis of each subject's higher (less distensible) value showed reduced distensibility in the vasectomised group (P = 0.006). This result lends support to the possibility that vasectomy may accelerate the development of peripheral arterial disease in man.

Age Factors↗
PubMed1983

Differential diagnosis of arterial disease of the lower limb using Doppler ultrasound.

Doppler arterial waveforms from the femoral and ankle arteries of 55 normal control subjects and 76 arteriopaths were analysed for Laplace transform coefficients, delta and omega omicron, and pulsatility index (PI). At the femoral artery delta was superior to PI in accurately detecting mild and moderate aortoiliac stenosis, as assessed from arteriograms. In the femoropopliteal segment, the ratio of omega omicron from femoral to ankle level compared favourably with PI damping factor in the detection of occlusive disease. The Laplace transform system provides a helpful diagnostic method in lower limb arterial disease.

Aorta↗