Biomedical subjects
Publications and source records attributed to M Horrocks.
A simple technique is described using a Doppler flowmeter to prevent malalignment of a vein graft during femorodistal reconstruction. In 63 non-reversed vein bypass grafts, this technique has been used and no evidence of malalignment has been found on subsequent completion arteriography.
Abdominal aneurysm repair in octogenarians is controversial. To justify surgery, survival with a reasonable quality of life is required. Between 1980 and 1988, 34 octogenarians underwent aortic aneurysm surgery (14 elective, 20 emergency). Of the 21 survivors, 20 were interviewed to determine their quality of life. At the time of interview the patients had a median survival of 19 months (range 4-67 months). Twenty age/sex matched normal patients, from the same GP population, were interviewed for comparison. A structured questionnaire was used to assess: physical mobility, activities of daily living, sleep and emotional problems. A symptom survey was also performed. The survival trend of elective patients was similar to that of a demographically similar 'normal' population. The survival trend of emergency patients returned to 'normal' after the first postoperative month. Quality of life of the 20 patients was comparable to the lifestyle enjoyed by normal subjects. Of the 20 patients interviewed, 18 had returned home after surgery. Elective and emergency aortic aneurysm surgery can be performed with reasonable survival and a good quality of life, and therefore cannot be denied to octogenarians on the basis of age alone.
BIPAS, a computerised vascular audit has been used to analyse the results of 203 carotid endarterectomies performed over a 5-year period in a vascular unit. In addition, all but two patients have been followed up with regular duplex scans. The indications and surgical techniques have remained similar over the study period though preoperative carotid arteriography is no longer considered essential and intraoperative monitoring with transcranial Doppler insonation is becoming routine. There were six perioperative deaths and 20 postoperative neurological defects. However, only three survivors had any long-term disability. It was not possible to identify any particular patients at high risk of perioperative stroke, although simultaneous major surgery and significant bilateral carotid endarterectomy seemed to be more hazardous. Routine follow-up using duplex scanning identified patients with late occlusion (5%) and restenosis (8%), but only three patients (1.5%) suffered a late stroke. Once the perioperative hazards of death and permanent stroke (4.4% in this series) have been overcome, carotid endarterectomy provides good protection against subsequent stroke.
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Fifty-six patients, 30 with superficial and 19 with deep groin wound infections, and seven with lymph fistulae with positive cultures within 30 days of arterial surgery, were identified after 661 operations (873 groins at risk) between September 1984 and August 1988. The commonest infecting organisms were Staphylococcus aureus, Pseudomonas aeruginosa and Proteus spp. In 33 patients the infection settled completely after treatment with culture specific antibiotics. These were given intravenously then orally for up to 6 weeks. Sixteen patients required debridement and excision of necrotic wound edges, including one who had an antibiotic infusion into the wound. Graft excision was performed in seven patients of whom five received an extra anatomic bypass. The need for graft excision was much greater (six versus one) for Dacron and/or polytetrafluoroethylene than for vein. In two lymph fistulae sartorius transposition and wound resuture were used. All groins healed, though three extremities were ischaemic following occlusion of the bypass. There were two deaths, one from myocardial infarction and one from pulmonary embolism and no major amputations. These results suggest that most infective groin problems may be successfully managed conservatively and that radical graft excision is only necessary for a few intractable cases.
Between 1986 and 1988, 38 patients (29 men and nine women), median age 65 years (range 38-85 years), underwent local intra-arterial streptokinase therapy for acute lower limb ischaemia. Three patient groups were identified: 15 with acute on chronic ischaemia (group 1), 12 postangioplasty (group 2) and 11 postfemorodistal bypass (group 3). Distal arteriographic run-off was a significant discriminant between success and failure in group 1 (n = 15, chi 2 = 11.5, P = 0.001) and in the overall group (n = 38, chi 2 = 17.2, P less than 0.001). In group 2, four patients with good run-off had an unsuccessful outcome; this was due in all cases to technical problems (haemorrhage in two and intimal dissection in two). In group 3, two patients with good run-off had unsuccessful streptokinase infusions. In both cases the graft failed in the early postoperative period (less than 30 days). By contrast, the four patients whose grafts occluded after 30 days had successful streptokinase infusions and long-term graft patency was achieved by further surgery and balloon dilatation. In all groups, no patient with a poor run-off had a successful outcome following streptokinase administration. The role of local intra-arterial streptokinase therapy in the critically ischaemic limb remains controversial, but these results suggest that an adequate run-off is an important factor in the selection of patients for treatment.
Conservative measures to improve claudication distance include advice on smoking, exercise, diet and weight reduction. Although the effects of smoking, exercise and diet are established, the effect of weight is less clear. The aim of this study was to investigate the effect of carrying extra weight on the maximum walking distance in stable claudicants. Twenty stable claudicants were exercised on a treadmill (3.5 km/h, 0 degrees slope) carrying 0, 2.5, 5, 7.5 and 10 kg weights in randomized sequence. Maximum claudication distance and ankle: brachial pressure indices were recorded. Patients were categorized into mild or severe claudicants depending on their ability to walk 200 m. A response index (RI) was calculated as the reduction in claudication distance per kilogram load; RI = [CD0-CD10]/10 m/kg, where CD0 and CD10 represent claudication distance with 0 and 10 kg weights, respectively. Claudication distance was significantly reduced in subjects carrying 5 kg or more (P less than 0.01). A linear relationship was demonstrated between the mean claudication distance and the load carried (r = 0.98, P less than 0.01) with a mean response index of 10.2 m/kg. The mean(s.e.m.) RI in mild claudicants (25.9(9.5) m/kg) was greater than the value observed in the severe claudicants (3.3(0.8) m/kg; P less than 0.01, Mann-Whitney U test). This study demonstrates that weight adversely affects claudication distance and suggests that weight reduction may deserve greater emphasis in the management of some patients with intermittent claudication.
The pathophysiological response to peripheral percutaneous transluminal balloon angioplasty in 20 patients was investigated using 111-Indium labelled platelets. Platelet deposition was quantified by measuring the degree of radioactivity uptake at angioplasty and control sites using a computer linked system and expressing the uptake as a ratio of angioplasty/control. Following platelet labelling, scans were performed before angioplasty and at 1, 24 and 48 h after angioplasty. To assess patency of the angioplasty, ankle brachial Doppler pressure indices were performed and supported by repeat angiograms if doubt of patency existed. All patients were followed-up at 1 week, 1 month and 6 months to correlate the degree of early platelet uptake with failure. The mean +/- sem platelet radioactivity ratio at the angioplasty site increased from 1.1 +/- 0.1 prior to the procedure to a peak of 2.1 +/- 0.3 at 1 h (p less than 0.01), 1.6 +/- 0.2 at 24 h (p less than 0.05), and 1.7 +/- 0.3 at 48 h (p less than 0.05). Angioplasties that failed within 6 months tended to have a higher maximum early platelet uptake (3.1 +/- 0.6) compared to successful angioplasties (1.9 +/- 0.3) but the difference was not significant in the numbers studied. This study provides a suitable model to assess the role of platelet accumulation in angioplasty failure and the influence of various antiplatelet regimes.
The diameter of the long saphenous vein has been shown to affect the outcome of femoro-distal bypass. Many surgeons regard a vein with a diameter of less than 3 mm as being unsuitable. The long saphenous vein was studied in 35 patients undergoing femoro-distal bypass. Diameter measurements of the vein were performed using an ATL duplex scanner at the groin, mid-thigh and knee. Measurements were performed preoperatively both at rest and with a venous occlusion cuff to dilate the vein, and subsequently at 7 days and 2 months after implantation. The mean diameter of the vein at the mid-thigh was 4.1 mm non-dilated, 5.1 mm with occlusion, 5.0 mm 7 days postoperatively and 5.2 mm at 2 months (ANOVA, p less than 0.05). The mean diameter of the vein at the knee was 3.9 mm non-dilated, 4.8 mm with occlusion, 4.8 mm at 7 days and 4.9 mm at 2 months after operation (ANOVA, p less than 0.025). In all five patients whose preoperative resting vein diameter at the knee or mid-thigh was less than 3 mm, preoperative dilatation occurred, such that the diameter became greater than 3 mm. These results suggest that by using a technique of venous occlusion at the time of pre-operative vein mapping, the functional diameter of the vein can be predicted and vein utilisation may be increased.
Computer-assisted impedance analysis is a newly developed technique to identify femoropopliteal and distal vein graft stenoses before failure. Pulsatile flow is measured from the proximal and distal graft by use of an 8Mhz Doppler velocimeter. A pulse volume recorder measures pulsatile pressure within the thigh and calf. Fourier transfer analysis is performed on paired Doppler pulse volume recorder waveforms and an impedance score derived for the thigh and calf, respectively. In a retrospective review of 50 nonreversed femoropopliteal/distal grafts performed for limb salvage, postoperative biplanar intraarterial digital subtraction arteriography was compared with impedance analysis. Arteriography showed graft or runoff stenoses in 22 grafts (at risk) and 28 normal grafts (controls). Impedance scores were significantly higher in the at risk group (0.58 + [0.43 to 0.72]*), when compared with the controls (0.34 + [0.30 to 0.38], p less than 0.001*). A thigh or calf impedance score of greater than 0.45 was able to detect 20 of 22 stenoses, including 6 lesions in grafts with normal resting and postexercise ankle pressures. This score was then applied prospectively and compared with serial biplanar digital subtraction arteriography in a further 56 femoropopliteal/distal bypasses for limb salvage. Thirty-three of 34 lesions were successfully predicted and impedance scores were significantly higher in the at risk limbs (0.56 + [0.44 to 0.68]*) when compared with the controls (0.38 + [0.35 to 0.41], p less than 0.001*). In this series impedance analysis proved more sensitive than resting or stressed ankle pressures and, unlike Duplex scanning, was able to detect runoff as well as graft stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)
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A retrospective review of 63 patients undergoing duplex scanning and angiography for suspected carotid artery disease was performed to evaluate the need for routine angiography before carotid endarterectomy. A consultant surgeon (M.H.) made a simulated management decision on the basis of a clinical summary and a duplex scan report. Twenty-four patients were selected for surgery without angiography; duplex scanning had a sensitivity of 100 per cent and a specificity of 90 per cent in the detection of internal carotid artery stenosis. In two cases duplex scanning misdiagnosed a total occlusion as a critical stenosis. Eighteen patients failed to meet the criteria for surgery and were referred for angiography. Twenty-one patients were selected for conservative treatment on the basis of the duplex scan report. Combining the surgical and conservative groups (45 patients), duplex scanning had a sensitivity of 96 per cent and specificity of 95 per cent for the detection of stenosis greater than 50 per cent. In the identification of a total occlusion, duplex scanning had a poor sensitivity of 50 per cent. These results suggest that routine angiography before carotid endarterectomy is unnecessary in selected patients but that a suspected occlusion should be confirmed by angiography.
The measurement of peripheral resistance (PR) is a useful technique for predicting the outcome of femorodistal bypass. In an attempt, noninvasively, to predict PR, Pulse Generated Runoff (PGR) was used to assess 35 consecutive patients undergoing femorodistal non-reversed vein bypass for critical ischaemia. The PGR subscores (anterior tibial, posterior tibial, peroneal, pedal arch status were correlated against the measured PR. Using multiple linear regression three resistance values were derived for runoff at different levels: (1) a single calf vessel (R1); (2) distal popliteal artery (R3); (3) irrespective of the level (R0). There was good agreement between the predicted resistances R0, R1 and R3 and the measured PR. In the single calf vessel group (R1) the limits of agreement (-0.41 to +0.39) and 95 per cent confidence interval (-0.16 to +0.14) with the measured PR were better than in the R0 and R3 groups. These levels of agreement are small enough to replace the measured PR with the predicted PR method. Using the appropriate resistance equation in a further prospective series of 14 cases, there was agreement between the predicted and measured PR (limits of agreement -0.67 to +0.41; 95 per cent confidence interval -0.26 to +0.15). These results confirm the value of PGR in the assessment of critically ischaemic limbs particularly with a single calf vessel. Calf vessel continuity with the pedal arch appears to be a major determinant of PR, particularly in the isolated calf vessel group. A non-invasive resistance value can be derived which will predict the intraoperative peripheral resistance and should help predict subsequent graft outcome.
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Up to 15% of abdominal aortic aneurysms are designated as inflammatory. They are characterized by marked fibrous thickening of the aneurysmal wall, with the fibrosis extending into the adjacent retroperitoneum. Thirty-five abdominal aortic aneurysms were studied, 15 inflammatory and 20 atherosclerotic. Of the inflammatory group, 10 were symptomatic and five asymptomatic. For each resection specimen, 59 microscopic features (variables) were scored semi-quantitatively. Discriminant function analysis showed that endarteritis obliterans, fibrosis around nerves or ganglia at the outer margin of mural fibrosis, and the thickness of the combined fibrotic media and adventitia gave a satisfactory high discrimination between atherosclerotic and inflammatory aneurysms. When these three variables are used together, a histological diagnosis of inflammatory aneurysm can be made with an expected accuracy in excess of 80%.
A prospective study of 370 patients who underwent 500 percutaneous transluminal angioplasties (PTAs) for lower-limb ischemia over a 7-year period was performed. A 97% follow-up rate was achieved. The first PTA was successful in 188 patients (51%). Of the failures, 31% were failed attempts at dilation and 73% occurred within 1 month of intervention. Of the patients with failed PTA, 39% underwent bypass surgery and 24% underwent amputation. The 30-day mortality rate was 3%, with 1% of the deaths attributed to PTA. The survival rate at 5 years for the successes was double that for the failures (P less than .0005). The best results were in femoropopliteal stenoses with two or three patent calf vessels (cumulative patency rate, 78% at 3 years) and the worst in femoropopliteal occlusions with one or no patent calf vessels (cumulative patency rate, 25% at 3 years). Log rank tests on the life-table data were used to show factors favoring a good outcome. It is concluded that PTA is the treatment of first choice in suitable patients and, although the failure of intervention in critical ischemia has a significant risk, it is a valuable addition to the therapeutic options in patients with little chance of surgical treatment.
A randomized trial was carried out in patients with occlusions of the femoro-popliteal artery to compare the passage of metal-tipped optical fibres with guide wires and catheters through the occlusions, prior to balloon angioplasty. The study was in a provincial English teaching hospital providing a vascular service for the area. Fifty patients were entered; 25 into the "laser" group and 25 into the "control" group. End points were (a) the success in passage through the occlusion and (b) the outcome 1 month after passage. Comparison of the groups showed no appreciable difference between the two methods with regard to age, sex, symptoms, incidence of diabetes, or previous myocardial infarctions. Successful passage through the occlusion followed by dilatation was achieved in 18 (72%) patients in the laser group and 20 (80%) in the control group. After 1 month, 13 (52%) arteries in the laser group were patent compared to 13 (57%) in the control group. Confidence limits for the difference in success of passage are -15% to +31%, and -24% to +33% for patency after 1 month. Since these limits include zero, it is unlikely that a longer trial would alter the difference between the two methods. The results suggest that the laser system currently in use is no better than conventional methods.