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Biomedical subjects

R J Lusby

Publications and source records attributed to R J Lusby.

At least 19 recordsLinked to original sources
PubMed2000

Clinical governance and the vascular surgeon.

BACKGROUND: Audit of adverse outcome might allow identification of substandard surgical results. To test this hypothesis statistical modelling was applied to two indicator vascular procedures (elective abdominal aortic aneurysm repair and carotid endarterectomy) with accepted adverse event rates. METHODS: Binomial statistical models for varying adverse event rates were constructed. A power calculation was used in an attempt to predict the case numbers required to determine substandard results for individual surgeons and vascular units. Two scenarios were considered: first a base adverse event rate of 6 per cent and surgical practice with 9, 12 and 24 per cent morbidity rates, and second a base adverse event rate of 3 per cent and surgical practice with 6, 9 and 12 per cent morbidity rates. RESULTS: A mean of 57 elective abdominal aortic aneurysm repairs and 70 carotid endarterectomies were performed per annum. The adverse event rate for both operations was 4 per cent. Power calculations revealed that 130 patients would need to be studied to detect a surgeon with an adverse event rate twice 6 per cent and over 280 patients would be required with an adverse event rate twice 3 per cent. To gather this number of patients 2 years of unit data and between 3 and 22 years of individual data would need to be studied for a base adverse event rate of 6 per cent. A base rate of 3 per cent requires 7-47 years for an individual and 4-65 years for the unit. With a base adverse event rate of 6 per cent, detection of widely variant surgical practice (four times the morbidity rate as base) requires only 21 procedures. CONCLUSION: Statistical modelling demands assumptions about accepted adverse event rates, confidence criteria and what constitutes substandard results. Data from large numbers of patients are required even for common operations with accepted adverse event rates. These data raise serious questions as to the feasibility of performing clinical governance on the basis of morbidity and mortality event rates alone.

Aortic Aneurysm, Abdominal↗
PubMed2000

Stent-graft treatment for bleeding from a presumed aortoenteric fistula.

PURPOSE: To describe a technique for the endovascular treatment of aortoenteric fistula. METHODS AND RESULTS: A 67-year-old man who had undergone aortobi-iliac grafting for aneurysmal disease 8 years previously presented with life-threatening upper gastrointestinal hemorrhage. Endoscopy after resuscitation did not identify the source of the bleeding. Computed tomographic (CT) scanning and angiography revealed pseudoaneurysm formation at the upper anastomosis 1 cm below the renal arteries. Measurements were taken for endovascular repair. Uncomplicated emergency aortic endografting for exclusion of the pseudoaneurysm was performed using a 28-mm x 3.75-cm AneuRx device. Gastrointestinal hemorrhage ceased. CT scanning at 6 months confirmed the absence of a pseudoaneurysm, and the patient remains symptom free at 18 months. CONCLUSIONS: Endovascular treatment of aortoenteric fistula may represent a technique for treating gastrointestinal hemorrhage and for lessening the morbidity and mortality of open repair.

Aged↗
PubMed1993

The natural history of asymptomatic carotid artery disease.

PURPOSE: The purpose of this article is to determine the natural history of carotid artery disease among asymptomatic patients with cervical bruits or other risk factors for stroke and to study the value of duplex ultrasonography in predicting future neurologic events. METHODS: Two hundred forty-two asymptomatic, unoperated patients, referred for evaluation of asymptomatic carotid artery disease, were followed prospectively with duplex ultrasonography. RESULTS: Fifteen ischemic strokes (6.2%) and 20 transient ischemic attacks (TIA) (8.3%) occurred in 34 patients during a mean follow-up of 27.4 months. Annual stroke, TIA, and combined event rates were 2.7%, 3.6%, and 6.2%, respectively. Although patients with 80% to 99% lesions had a 20.6% annual event rate, most events occurred contralateral to these lesions; the vessel-specific annual event rate for 80% to 99% disease was 5.1%. Only one of 15 strokes occurred ipsilateral to an 80% to 99% stenosis. Echolucent plaques were associated with TIA and stroke (5.7% annual vessel event rate vs 2.4% for echogenic plaques, p = 0.03). Disease progression was highly correlated with TIA and stroke (p < 0.0001), but it usually occurred in association with rather than before ischemic events, thus proving more useful in explaining pathogenesis than in predicting future events. There was no association between aspirin use and TIA, but patients taking aspirin had a threefold higher annual stroke rate (1.6% vs 4.8%, p = 0.027). CONCLUSIONS: This study, while confirming significant risk for asymptomatic patients with critical stenosis or echolucent plaque, demonstrates the importance of contralateral disease and the absence of orderly progression from minimal disease through high-grade stenosis to symptomatic cerebral ischemia. TIA and stroke commonly occur in association with abrupt, unpredictable, quantum changes in carotid artery disease.

Adult↗
PubMed1991

Concomitant renal artery revascularization and aortic reconstruction in the adult patient.

Concomitant renal artery revascularization and aortic reconstruction in the adult patient are thought to be associated with a high degree of morbidity and mortality. This has been attributed to the diffuse nature of atherosclerosis generally present in these patients and, as a consequence, a poor overall medical condition. Although this series confirms the fragile pre-operative nature of these patients it demonstrates that, with careful surgical management, they can be treated effectively.

Aged↗
PubMed1991

Effects of Furegrelate (Upjohn 63557A) on patency and platelet deposition after canine carotid endarterectomy.

Platelet deposition upon endarterectomy sites is a likely cause for early postoperative thrombosis, embolism and restenosis. Platelets aggregate by the thromboxane-prostacycline mechanism. Thromboxane synthetase inhibitors which have been safely administered to humans should reduce platelet deposition after surgical therapy and therefore reduce peri-operative mortality and the prevalence of stroke. A randomized prospective controlled trial was designed to determine vessel patency and platelet deposition associated with the use of 3 mg/kg and 30 mg/kg of Furegrelate (Upjohn U63557A) daily in dogs, who were to have carotid endarterectomy. The 46 treated and 46 control dogs had total carotid patency of 96% and 76% respectively (P less than 0.01). Fourteen dogs treated with 30 mg/kg Furegrelate had no occlusions, compared with a 19% prevalence in 13 controls (P less than 0.02). Furegrelate 10 mg/kg significantly lowered platelet aggregation. Platelet deposition was not significantly changed, however. The reason for this disparity was a probable persistence of vessel wall factors which promoted platelet deposition. This approach might therefore lower rates of peri-operative thrombosis but it would be very unlikely to alter the incidence of restenosis or embolism. Further research could be directed towards modifying the stimuli for platelet deposition upon the endarterectomy site.

Animals↗
PubMed1990

Microcomputer database and system of audit for the vascular surgeon.

We have set up a vascular database based upon an IBM personal computer in the vascular unit at Repatriation General Hospital, Concord, using 'Dataease'. This is commercially available software that allows the development of a database by users with little or no programming knowledge. The database is menu driven and designed to record details of admissions, indications for surgery, operations, complications and follow-up and has been set up as a prospective project from 1 January 1989 after a pilot study in 1988. Currently, interns, residents and registrars enter data directly onto the computer, providing an excellent teaching and review medium. Unit audit is easy as the program is completely menu driven and there are more than 100 customized reports written, ranging from providing simple complication details to complex reports deriving graft cumulative patency rates. This system also provides for 'instant' discharge letters which have markedly improved communication with the general practitioner.

Hospital Information Systems↗
PubMed1989

Internal carotid artery occlusion: effect of contralateral flow reduction in inducing symptoms.

Cerebral ischemic attacks ipsilateral to an occluded internal carotid artery (ICA) continue in more than 16% of patients. With common carotid artery compression on the side of ICA occlusion in 53 patients, the mean (+/- SEM) ophthalmic systolic pressure/brachial systolic pressure (OSP/BSP) ratio fell from 0.58 +/- 0.013 to 0.42 +/- 0.020 (p less than 0.001), without any cerebral ischemic symptoms. Compression of the contralateral patent common carotid artery resulted in the ophthalmic systolic pressure/brachial systolic pressure ratio dropping from 0.67 +/- 0.012 to 0.29 +/- 0.017 (p less than 0.001) on the patient side and from 0.58 +/- 0.013 to 0.48 +/- 0.018 (p less than 0.001). Twenty-six of 53 patients (49%) developed ischemic symptoms in response to compression of the remaining patent ICA system. In contrast, only 8 of 122 patients (6.5%) without ICA occlusion developed any symptoms of cerebral dysfunction (p less than 0.001). This study suggests embolic events rather than flow reduction may be of greater importance in the production of new symptoms and that contralateral flow is critical to normal cerebral function in half the population with ICA occlusion.

Aged↗
PubMed1989

The role of plaque morphology and diameter reduction in the development of new symptoms in asymptomatic carotid arteries.

To determine the natural history of changes in plaque morphology and luminal diameter of atherosclerotic carotid arteries, we used duplex scanning to follow-up (1) the contralateral artery in 289 patients who had undergone carotid endarterectomy, with a mean follow-up 22 months and a range of 0 to 48 months and (2) the carotid arteries in 130 patients who had no surgical treatment and had been symptom free, with a mean follow-up period of 15 months and a range of 0 to 48 months. Plaques were graded as to the ratio of echolucency to echogenicity, with type 1 being most echolucent and type 4 being most echogenic. A normal-appearing artery was classified as type 5. Heterogeneous plaques (types 1 and 2) occurred significantly more (p less than 0.001) in symptomatic preoperative arteries than in asympatomatic arteries. Follow-up of the asymptomatic vessels showed that the majority of plaques either remained the same or became more echogenic (fibrous). Approximately one fourth of plaques in each group degenerated (more echolucent). Thirty-one patients (10.7%) developed new symptoms in the contralateral asymptomatic group, with 10 patients (3.5%) having strokes. Fourteen of 130 (10.8%) patients, or 5.4% of vessel territories at risk, in the primary asymptomatic group developed new symptoms, with only two strokes occurring. In the contralateral asymptomatic group those patients who initially had greater than 75% stenoses fared worse than those with primary asymptomatic disease with greater than 75% stenosis. Although the overall development of new symptoms is low in both populations, our data indicate that those patients with heterogeneous plaques or whose plaques have undergone change may be at risk for new symptoms. Longer follow-up studies are needed to define the role of plaque changes in the development of symptoms. For now we advocate a conservative "wait and see" approach to symptom-free patients with greater than 75% stenoses and calcified plaques. We suggest a more aggressive approach, recommending early surgical intervention, to those few patients with heterogeneous plaques.

Aged↗
PubMed1989

Carotid artery atheroma: ultrasound appearance in symptomatic and asymptomatic vessels.

The distribution of carotid plaque ultrasound appearance has been evaluated using duplex ultrasound in symptomatic and asymptomatic patients. There were 134 patients with unilateral carotid territory symptoms who subsequently underwent endarterectomy of the symptomatic carotid bifurcation, and 92 asymptomatic patients. Both carotid bifurcations in all patients were examined, thus providing three groups of vessels for study: (i) asymptomatic vessels in asymptomatic patients (n = 184); (ii) asymptomatic vessels in symptomatic patients (n = 134); and (iii) asymptomatic contralateral vessels in symptomatic patients (n = 134). Ultrasound appearances were classified as types 1-4. This classification has previously been compared prospectively with endarterectomy specimen pathology where the more echolucent type 1 and 2 lesions correlated well with the presence of intraplaque haemorrhage or ulceration. In the symptomatic arteries, type 1 and 2 lesions were predominant, whereas in the asymptomatic patients the most common lesions were types 3 and 4. This difference was statistically significant (P less than 0.01). Evaluation of the asymptomatic contralateral vessel in the symptomatic patients showed a pattern of plaque type distribution between the other two groups.

Aged↗
PubMed1989

Abnormal pre-operative creatinine levels and renal failure following abdominal aortic aneurysm repair.

Renal failure is a well-documented complication of abdominal aortic aneurysm surgery. This study examined the use of pre-operative creatinine levels as a predictor of the development of acute postoperative renal failure. There was a statistically significant association between raised pre-operative creatinine levels and the subsequent development of acute renal failure (P less than 0.05). The results of this study demonstrate the need for particular attention to be diverted to the protection of renal function in patients with pre-operative raised creatinine levels.

Acute Kidney Injury↗
PubMed1989

Infrarenal aortic aneurysm: unusual cause of paraparesis.

A male patient recently presented to our Unit with anterior spinal artery syndrome involving his lower limbs. This neurological condition was an unusual manifestation of an infrarenal abdominal aortic aneurysm with local dissection occluding the infrarenal lumbar arteries. The incidence, anatomy, aetiology, and management of the condition associated with aortic aneurysms are described.

Aged↗
PubMed1988

Amaurosis fugax: the importance of carotid plaque morphology.

Amaurosis fugax, or transient monocular blindness, was first associated with carotid bifurcation disease in 1951. Although amaurosis fugax is often considered by vascular surgeons to be premonitory for cerebral stroke, recent studies indicate that this disease process may be more benign than previously thought. A total of 97 patients presented with amaurosis fugax to our vascular laboratory from November 1983 to January 1988. There were 81 males and 16 females, mean age 67.2 years. The common, internal and external carotid arteries were imaged in standard longitudinal and cross-sectional views. Repeat scans were performed at six months and 12 months after the first visit, then yearly thereafter. Out study confirms the correlation between heterogeneous, complex carotid plaques and the development of amaurosis fugax. Endarterectomy can safely be performed in this group of patients, preventing further symptoms or development of stroke. We advocate duplex scanning to assess the carotid bifurcation and allow non-invasive follow-up of disease progression.

Adult↗
PubMed1988

Selective use of heparin in aortic surgery.

The incidence of distal ischaemia following aortic reconstruction may be as high as 25%, despite the use of systemic heparin. As anticoagulation may be associated with excessive operative blood loss, a retrospective study was performed to assess the prevalence of these problems, in a consecutive series, during a 30-month period. Evaluation of reconstruction was possible in 161 patients with aneurysm and 38 patients with occlusive disease. The incidence of vessel occlusion was 21% in the occlusive and 4% in the aneurysm group (P less than 0.05). Four of seven patients who had major vessel occlusion had serious complications, and there were two resultant deaths. These problems occurred despite the administration of heparin. Blood loss and operating time were quantitated in the patients who had resection for aortic aneurysm. Both were significantly longer in patients who received heparin (P less than 0.05) and the differences were maintained when patients were stratified according to increments in dose or operating time, and according to whether woven tube or bifurcation grafts were performed. It was concluded that aneurysm surgery, in the absence of distal occlusive disease, could be safely performed without the use of systemic heparin, but surgery for occlusive disease still requires heparinization.

Aged↗
PubMed1988

Is there still a place for carotid endarterectomy?

Carotid endarterectomy is a controversial procedure. Despite the increasing incidence of its performance, there have been as yet no prospective randomised trials which have conclusively shown its benefits for patients with carotid artery atherosclerosis. Until the results of such studies become available, a rational approach to the estimation of stroke risk in these patients can be based on an understanding of their carotid plaque morphology. Over the past 4 years we have examined plaque morphology with a B-mode duplex scanner and have been able to categorise the degree of heterogeneity of plaques into 4 types depending on the degree of plaque echolucency. We have shown good correlation between the preoperative plaque type and the operation specimen. Furthermore, we have found that the risk of symptom development correlates with the development of a more echolucent plaque. Finally, while plaque heterogeneity may be a good predictor of the risk of embolism from the plaque, other deleterious factors such as hypertension may determine the severity of the ensuing neurological event. The approach in our unit has been to operate on symptomatic patients with demonstrated high grade or heterogeneous carotid artery atherosclerosis appropriate to the patient's symptoms. We have found that most asymptomatic patients have subcritical stenoses and dense homogeneous plaques, and we treat these conservatively. On the other hand, surgery is recommended for asymptomatic patients with high grade stenoses and heterogeneous plaques. We have been able to follow this policy with a morbidity and mortality of 2.6% and 1.0% respectively.

Arterial Occlusive Diseases↗
PubMed1985

Prostacyclin production in regions of arterial stenosis.

The effect of abnormal flow dynamics on prostacyclin (PGI2) production by intact endothelium is unknown. To investigate this we studied the effects of graded stenoses on vessel wall PGI2 production in dogs (n = 8) whose femoral and carotid arteries (n = 32) were narrowed by machine-milled clips, producing 1.0 cm segmental stenoses of 25%, 50%, 75%, and 90% diameter reduction. Three dogs were injected with Indium 111-labeled platelets and 12 vessels were scanned for platelet deposition. All stenotic vessels were excised at 6 weeks for histologic study (hematoxylin-eosin section and immunohistochemistry for factor VIII) and PGI2 radioimmunoassay (as the metabolite 6-keto PGF1 alpha). All vessels remained patent with no thrombus formation in any segment. Vessel imaging in platelet-labeled animals showed no significant deposition. Histologic analysis demonstrated an intact endothelial surface in the stenotic segments, confirmed by the demonstration of factor VIII production by these cells. PGI2 production (per unit surface area) by the arterial segments with greater than or equal to 50% stenosis markedly exceeded the PGI2 production by the normal proximal and distal segments (p less than 0.0002) and showed further significantly increased production with increasing degrees of stenosis (p less than 0.00001). The data indicate increased PGI2 production by normal endothelium in regions of arterial stenosis. The mechanism of this increase is unknown, but this endothelial "turn on" effect may serve to inhibit deposition of platelets and thrombus formation in the presence of disordered flow patterns.

Animals↗
PubMed1984

Late results following surgical management of vascular graft infection.

Ninety-two patients underwent surgical treatment for 59 prosthetic graft infections and 33 secondary aortoenteric fistulas. Definitive treatment was accomplished with a low perioperative mortality rate (14%). Long-term follow-up confirmed that most patients were cured of their infection or fistula, and 88% of the patients who survived the perioperative period (67 of 76) had no further evidence of infection when followed up from 10 months to 12 1/2 years postoperatively. The 12% late mortality rate (9 of 76) was secondary to persistent infection and aortic stump disruption. When perioperative and late deaths in both groups are combined, 67 of 92 patients (73%) were cured of their prosthetic graft infection. Factors associated with a favorable prognosis for survival and cure of infection were autogenous reconstruction and possibly staged operative repair. Poor prognosis for survival and cure of infection resulted from aortic stump disruption, persistent infection, and retained graft material. Significant morbidity (amputation and multiple operative procedures) was related to the severity of underlying vascular disease, the inadequacy of extra-anatomic reconstruction, and in some cases progression of vascular disease. The major challenges in the treatment of graft infection at present are the preoperative identification of limited graft infection and the successful management of the interrupted aorta. Complex and innovative reconstructive procedures continue to be necessary to ensure limb salvage and remain a considerable technical challenge. Nonetheless, the prospects for cure as reported in this series justify an aggressive operative approach. A successful outcome following definitive treatment of these devastating complications is possible for the majority of affected patients.

Aged↗