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Biomedical subjects

B R Hopkinson

Publications and source records attributed to B R Hopkinson.

At least 55 records · Page 3Linked to original sources
PubMed1997

The anatomy of abdominal aortic aneurysms: implications for sizing of endovascular grafts.

OBJECTIVE: To determine the full range of aorto-iliac anatomy of patients with abdominal aortic aneurysms (AAAs) and thence the range of endovascular graft sizes required to deal with the majority of AAAs. DESIGN: Analysis of preoperative spiral CT measurements. MATERIALS: One hundred and sixty-eight patients with AAAs. METHODS: Multiplanar reconstruction measurements were taken of proximal aortic neck diameter and length, lowermost renal artery to the aortic bifurcation distance and length and diameter of common iliac arteries. Based on these measurements a range of graft sizes that would fit the majority of AAAs was determined. RESULTS: Ranges of anatomical variables were as follows: proximal aortic neck diameter 18-30 mm, renal artery to aortic bifurcation distance 93-210 mm, common iliac artery length 13-108 mm, common iliac artery diameter 6-67 mm. Over 750 graft sizes would be required to cover all anatomical combinations using a one-piece aorto-uni-iliac graft. CONCLUSION: A wide variety of aorto-iliac anatomy exists in patients with AAAs. The large number of graft sizes required to deal with the majority of AAAs makes the production of one-piece endovascular grafts commercially impractical. A proposed two-piece modular graft would allow the majority of AAAs to be treated using only 16 graft sizes.

Aged↗
PubMed1997

European experience with a system for bifurcated stent-graft insertion.

PURPOSE: To test an endovascular aneurysm exclusion system in the presence of a wide range of challenging anatomic features. METHODS: Bifurcated endovascular stent-grafts were inserted in 52 patients and followed with serial computed tomography for up to 3 years. The device underwent several modifications during this time, the most significant of which represent the difference between the homemade (n = 42) and industry-made (n = 10) versions. RESULTS: The initial procedural success rate was 92% in the homemade group and 100% in the industry-made group. In the 3 years of follow-up, the long-term success rate was 64% in the homemade group and 90% in the industry-made group. The primary reasons for failure in the homemade group were graft thrombosis due to kinking early in the series and proximal stent migration later in our experience. All cases of migration occurred when the neck was < 15 mm in length, the neck was lined with thrombus, or the stent was implanted > 15 mm from the renal arteries. Kinking was subsequently overcome by implanting Wallstents throughout the graft limbs. The sole failure in the industry-made group was a case in which collateral perfusion reached the aneurysm through patent lumbar arteries. CONCLUSIONS: The fruits of this experience are a better technique, a better device, and, most importantly, a better understanding of the system's limits, as reflected in the current selection criteria.

Angiography↗
PubMed1997

Influence of abdominal aortic aneurysm size on the feasibility of endovascular repair.

PURPOSE: To assess the effect of abdominal aortic aneurysm (AAA) size on overall aneurysm morphology with special attention to possible relationships among various anatomic variables that determine the feasibility of endovascular repair. METHODS: One hundred sixty-eight patients were assessed with spiral computed tomographic angiography to measure the length and diameter of the AAA, the proximal neck, and the common iliac arteries. Anatomic variables were correlated with aneurysm size using Spearman's rank order correlation coefficients (rS); comparisons among small, intermediate, and large aneurysms were made using the Chi-square test. RESULTS: Correlations between aneurysm size and the anatomic variables above were weak. The strongest association was between aneurysm size and aortic length (rS = 0.41, p < 0.001). Subgroup analysis showed no difference in proximal neck length, neck diameter, or overall suitability for endovascular repair between aneurysms greater or smaller than 5.5-cm diameter. However, significantly more short (< 1.5 cm), wide (> 3 cm), and hence, unsuitable proximal necks were found in patients with aneurysms > 7 cm in diameter (chi 2 = 7.8, p < 0.01). CONCLUSIONS: Shortening and widening of the proximal neck seems to increase with aneurysm size but only after the aneurysm expands beyond 7 cm in diameter. Aneurysms with diameters in the 4.5- to 5.5-cm range are no more suitable for endovascular repair than those between 5.5 and 7 cm. The lack of any significant correlation between anatomic variables emphasizes the need for accurate preoperative assessment of the anatomy of each individual patient before endovascular repair.

Aorta, Abdominal↗
PubMed1997

Results of 100 cases of pulse-spray thrombolysis for acute and subacute leg ischaemia.

BACKGROUND: Pulse-spray thrombolysis is a rapid technique for the treatment of limb ischaemia of recent onset. Early results have been published but the longer term results are not known. METHODS: This study consisted of a series of 100 legs with acute and subacute ischaemia treated using this method with a follow-up interval of up to 3 years. Eighty-three limbs were classified as Fontaine grade III or IV and 42 had a sensory or motor deficit. Sixty-seven limbs were treated with pulse spray alone and 33 had an additional low-dose infusion. In 71 cases an additional catheter-directed intervention was required. RESULTS: Median duration of lysis was 135 (range 35-1540) min and median dose of recombinant tissue plasminogen activator used was 18 (range 4-61) mg. Complete radiological patency was achieved in 79 limbs and the ankle:brachial pressure index improved from a median of 0 (range 0-0.8) to 0.8 (range 0-1.5) (P < 0.0001). At 30 days ten patients had died, eight needed amputation and a further 11 had rethrombosed. Cumulative limb salvage rate at 30 months was 79 per cent (standard error 8) and the estimated cumulative patency rate for successful cases was 72 per cent (standard error 10). The incidence of major bleeding was 7 per cent and of minor bleeding 24 per cent. There were no haemorrhagic strokes but three thrombotic strokes occurred within 30 days of thrombolysis. CONCLUSION: Pulse-spray thrombolysis achieves rapid and safe revascularization of acute and subacute leg ischaemia.

Adult↗
PubMed1997

Anatomical suitability of abdominal aortic aneurysms for endovascular repair.

BACKGROUND: Aortic aneurysm anatomy is crucial when considering patients for endovascular repair. The aim of this study was to determine the proportion of patients with aortic aneurysm suitable for endovascular repair with three different graft-stent systems. METHODS: Spiral computed tomographic angiography was used to assess the anatomy of 154 abdominal aortic aneurysms. Measurements were made of aneurysm neck length and diameter, renal artery to aortic bifurcation length, common iliac artery diameter and length, and external iliac artery diameter. Aneurysms were assessed for anatomical suitability for currently available aortoaortic, aortobi-iliac and aortouni-iliac devices. RESULTS: Six patients (4 per cent) had a distal aortic neck suitable for implantation of a straight aortic graft. Fifteen patients (10 per cent) had arterial anatomy suitable for implantation of a bifurcated graft and 85 (55 per cent) patients were suitable for endovascular repair with an aortouni-iliac graft. The primary reasons for unsuitability were: proximal neck length less than 1.5 cm (44 patients), proximal neck diameter greater than 3.0 cm (12), and angulation of the proximal neck (three). A further ten patients were considered unsuitable for an aortouni-iliac graft because of bilateral common iliac artery aneurysms (four), tortuous iliac arteries (four) and narrow external iliac arteries (two). CONCLUSION: The aortouni-iliac device has the widest applicability of the currently available endovascular systems but open repair remains the only option for a large proportion of patients.

Aged↗
PubMed1997

Role of Gritti-Stokes amputation in peripheral vascular disease.

The perigenicula lower limb amputations performed for peripheral vascular disease in Nottingham between April 1987 and September 1992 were reviewed. Of the 434 amputations, 173 were below-knee amputations (BKA), 144 Gritti-Stokes amputations (GSA) and 117 above-knee amputations (AKA). The 30-day mortality was significantly greater for AKA patients than either GSA or BKA patients. There was no difference in mortality within 30 days of amputation between GSA and BKA. Re-amputation rate to a more proximal level was significantly higher in BKA compared with GSA. Mobility after prosthetic rehabilitation was assessed using the Stanmore grading. A greater number of patients achieved mobility grade III and above in the GSA and BKA groups when compared with the AKA group, but there was no significant difference between GSA and BKA groups. At follow-up, a median of 23 months after amputation, there was a tendency for more patients to have given up using their limb prosthesis in the GSA group than either the BKA or AKA groups. However, there remained no significant difference between the BKA and GSA groups in the numbers of patients who remained successfully rehabilitated to Stanmore grade III or above. When a BKA is not possible, GSA offers a better prospect for rehabilitation compared with AKA in patients with occlusive arterial disease.

Adult↗
PubMed1996

Clinical experience with a bifurcated endovascular graft for abdominal aortic aneurysm repair.

PURPOSE: The purpose of this study was to test a transfemoral system of bifurcated endovascular graft insertion for aortic aneurysm repair. METHODS: Bifurcated endovascular grafts were inserted through bilateral femoral artery cutdowns in 41 patients. The results were assessed by completion angiography and follow-up computed tomography. RESULTS: The second half of the study included more aneurysms 6 cm or larger (p < 0.05) and more instances of short proximal neck (p < 0.05), proximal neck angulation (p < 0.05), and iliac angulation (p < 0.05). Despite the increasingly challenging anatomy, the results were better in the second half of the study as illustrated by the lower overall combined morbidity/mortality rate (15% vs 50%) and higher overall success rate (85% versus 65%). The mortality rate for the series as a whole was 7.5%. Mean follow-up was 18.8 months for the first 20 patients and 10.9 months for the second 20. The commonest complication in the first half of the study was graft thrombosis (n = 5). This complication was absent from the second half of the study because of routine adjunctive stenting. Two patients died of complications of endovascular repair. In both cases aneurysm rupture on the third postoperative day was associated with coagulopathy and angiographic signs of perigraft leak. CONCLUSION: Aneurysm exclusion with a bifurcated endovascular graft was feasible in a wide range of patients, but when the aneurysm was not entirely excluded from the circulation, the risk of rupture persisted.

Aorta, Abdominal↗
PubMed1996

Haemodynamic and metabolic response to endovascular repair of infra-renal aortic aneurysms.

We have examined whether or not endovascular insertion of a bifurcated aorto-iliac graft resulted in greater intraoperative haemodynamic and metabolic stability than that achieved during conventional open graft placement. We studied 20 patients prospectively during surgery for asymptomatic infra-renal aortic aneurysm. All patients received the same anaesthetic technique. Haemodynamic data were collected continuously using indwelling radial artery and pulmonary artery catheters, allowing calculation of mean arterial pressure (MAP), cardiac output (CO) and systemic vascular resistance (SVR). Blood samples were obtained for measurement of serum lactate concentrations. Variables were compared within each group before and after specific critical events, namely occlusion of femoral or aortic blood flow, or both, and sequential reperfusion of each lower limb. Patients undergoing open repair showed significant changes in CO, MAP and SVR related to aortic cross-clamping and lower limb reperfusion, and a significant increase in blood lactate concentration after distal tissue reperfusion. The only significant changes during endovascular repair were a transient increase in SVR secondary to application of the femoral artery clamps, and sequential decreases when each limb was reperfused. Endovascular aneurysm repair imposed significantly less intraoperative haemodynamic and metabolic stress on the patient compared with conventional open surgery.

Aged↗
PubMed1996

ADP-induced P-selectin expression on platelets as a predictor of successful thrombolysis.

Unlike coronary thrombolysis, the role of platelet activity in the outcome of local thrombolytic therapy for peripheral ischaemia is not well understood. In the present study ten patients undergoing local pulse spray thrombolysis (PST) with recombinant tissue-type plasminogen activator (rt-PA), six patients undergoing conventional infusion thrombolysis (CT) with rt-PA and another six patients undergoing arteriography with iopamidol were studied. Venous blood samples obtained before and after the procedure were analysed using a flow cytometric technique for detection of platelet activation after labelling platelets with VH10, a monoclonal antibody against P-selectin. In the present study no significant differences were observed in P-selectin expression before and after any of the procedures, except that P-selectin expression following ADP stimulation was reduced in patients who had received conventional thrombolysis. Unexpectedly, we observed relatively greater P-selectin expression, particularly after ADP stimulation, both before and following thrombolysis in ten patients in whom thrombolysis was successful compared with six patients in whom thrombolysis was unsuccessful. ADP-induced P-selectin expression on platelets may therefore be a useful predictor of outcome of peripheral intra-arterial thrombolysis.

Adenosine Diphosphate↗
PubMed1996

Lymphoscintigraphy and colour Doppler sonography in the assessment of leg oedema of unknown cause.

Oedema of the lower limbs may be associated with a number of factors, most commonly a lymphatic or venous abnormality. Generally effective treatment options are only available with venous disorders. The aim of this study is to show that a combination of duplex Doppler sonography and lymphoscintigraphy in patients with limb oedema will help to determine the aetiology and thus identify patients for whom treatment is appropriate. 32 patients presenting with unexplained oedema involving the lower limb have been studied. Each patient underwent Doppler sonography followed by lymphoscintigraphy. In 16 patients the lymphoscintigraphy was abnormal, showing absent or poorly visualized lymphatics. The Doppler study was abnormal in 17 patients, nine of whom went on to receive definitive surgical treatment. In five patients both studies were abnormal and there were six cases where both investigations were normal. It is concluded that in the great majority of referrals (82%), the combination of lymphoscintigraphy and Doppler ultrasound is a satisfactory means of assessment of patients with unexplained limb oedema.

Adolescent↗
PubMed1996

Randomized controlled trial of the effect of mannitol on renal reperfusion injury during aortic aneurysm surgery.

The effects of mannitol on renal impairment following infrarenal aortic aneurysm repair were studied. Patients received either mannitol 0.3 g/kg (n = 15) or saline (n = 13) as a rapid intravenous infusion before aortic cross-clamping. One patient in the control group developed fatal postoperative renal failure but there was no renal failure in the mannitol group. Two patients treated with mannitol died from perioperative myocardial infarction. There were no significant differences in postoperative blood urea level, serum creatinine concentration or creatinine clearance between mannitol and control groups. In patients who had mannitol there was a significant diuresis on the first day after operation (mean urine output 2250 ml) compared with before operation (1557 ml) (P = 0.007). Compared with controls, patients treated with mannitol had lower mean (s.e.m.) postoperative levels of urinary albumin (160(32) versus 500(140) mg per mmol creatinine; P = 0.036) and N-acetyl glucosaminidase (143(34) versus 271(70) mumol per mmol creatinine; P = 0.04) indicating a reduced level of subclinical glomerular and renal tubular damage. These data demonstrate that mannitol reduces subclinical renal injury following infrarenal aortic aneurysm repair.

Aged↗
PubMed1995

Immediate and early follow-up results of purse spray thrombolysis in patients with peripheral ischaemia.

Pulse spray thrombolysis is a technique of accelerated peripheral thrombolysis which has been evaluated in 38 patients, 29 with threatened limb viability and nine with a viable but critically ischaemic limb. The median length of occlusion was 26.5 (range 3-65) cm. The lytic agent used was recombinant tissue plasminogen activator (rtPA), injected manually via a pulse spray catheter at a concentration of 0.33 mg/ml and a bolus size of 0.2 ml. The median total dose of rtPA was 18 (range 5-35)mg. Patency and flow were completely restored in 34 of 38 patients and clinical success at 30 days was maintained in 27 of 38. The median lysis time was 120 (range 35-1125) min, compared with a median duration of 1545 (range 42-5760) min in 120 consecutive patients previously treated with conventional low-dose infusion thrombolysis using rtPA. This represents a 12-fold reduction in lysis time (P < 0.001). The overall estimated cumulative limb salvage rate for the 38 patients who entered the study was 84 per cent and the cumulative patency rate for the 34 patients in whom patency was restored was 74 per cent at 18 months follow-up. Pulse spray thrombolysis rapidly restores patency with good limb salvage at 30 days; the benefit is sustained even in patients with limbs at immediate risk of irreversible ischaemic injury who are not considered suitable for conventional thrombolysis.

Adult↗