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.

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.

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.

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.

Carotid endarterectomy. The timing of perioperative antiplatelet therapy by indium 111 labelled platelets study in canines.

Bilateral carotid endarterectomy (CEA) was performed in a series of 16 dogs, one of the arteriotomies being closed by direct suture and the other with an autologous vein patch. Platelets obtained at the induction of the anaesthetic were labelled with Indium 111 Oxine and subsequently re-infused prior to restoration of blood flow. Post-operative sequential platelet counts using a Selo CSZ counter were undertaken, which demonstrated a substantial rise at the sites of CEA. These counts rose to peak levels between 7-88 minutes after declamping with a median peak time of 20 minutes. Continued high levels of labelled platelet accumulation persisted for 48-96 hours following CEA and in some instances persisted for three weeks. These studies suggest that antiplatelet agents should therefore be active when carotid declamping occurs and administered for at least three weeks following CEA.

Carotid artery atheroma: comparison of preoperative B-mode ultrasound appearance with carotid endarterectomy specimen pathology.

This paper describes a prospective study comparing the preoperative Duplex ultrasound appearance of carotid bifurcation atheroma with the pathological characteristics found in the endarterectomy specimens of the same vessels. Initial studies of carotid atheroma using Duplex scanning classified plaques into heterogeneous and homogeneous and found a strong correlation between heterogeneous lesions and the presence of intraplaque haemorrhage or ulceration in the endarterectomy specimen. The B-mode classification of plaque appearance described in this paper is an expansion of the above classification. The study group comprised 220 patients who underwent 244 procedures. The indication for carotid endarterectomy was symptomatic disease in the great majority of cases. We found a high incidence of unstable plaque pathology in the operative specimens, and a predominance of the more echolucent ultrasound plaque appearances (types 1 and 2). There is a statistically significant relationship (p less than 0.001) between ultrasound appearance types 1 and 2 and the presence of either intraplaque haemorrhage or ulceration in the endarterectomy specimen.

Carotid artery disease: the influence of diabetes mellitus.

Patients with diabetes mellitus are more prone to stroke than non-diabetic patients. Using Duplex ultrasound imaging of the carotid bifurcation, we have found it possible to classify atherosclerotic plaques into four groups which appear to reflect the plaque pathology. Using this classification we have found that diabetics and non-diabetics have similar ultrasound plaque type distributions in symptomatic patients. Further subdivision of the diabetic patients on the basis of their mode of diabetic control has shown that insulin treated diabetics tend to show little evidence of intraplaque haemorrhage and ulceration. These features suggest that factors other than atherosclerosis at the carotid bifurcation may be responsible for the increased stroke risk in diabetic patients. Diabetic microangiopathy and reduced vessel compliance due to medial calcification have been suggested as possible factors. Insulin treatment of diabetics may protect against the development of occlusive atherosclerosis.

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.

Intravenous rupture of abdominal aneurysms: diagnostic and pathological considerations.

Seven cases of abdominal arteriovenous fistula secondary to aneurysm are reported. There were five aortocaval fistulae, one aortolumbar vein fistula, and one iliac artery to vein fistula. Three of five aortocaval fistulae were diagnosed pre-operatively. One in-hospital death occurred, and one post-hospital death. An analysis of the diagnostic patterns is made in an attempt to increase pre-operative diagnosis.

Ascending cinevenography in chronic venous insufficiency: a comparison with ambulatory venous pressure measurements.

Thirty-seven patients (49 limbs) with chronic venous insufficiency who were being considered for venous surgery were studied using a modified technique of ascending venography (Ascending cinevenography) and ambulatory venous pressure (AVP) measurements. AVP and ascending cinevenography results, in each patient, were assessed by a different investigator, each of whom was blind to the other result. The results of AVP measurements and ascending cinevenography were then compared. There is good correlation between AVP measurements and results of ascending cinevenography. Ascending cinevenography can be used instead of combined ascending and descending venography.