Biomedical subjects

R J Lusby

Publications and source records attributed to R J Lusby.

41 records · Page 3Linked to original sources

PubMedDate not supplied

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.

Aged↗

PubMedDate not supplied

The spectrum of carotid artery disease in asymptomatic patients.

A spectrum of asymptomatic patients with carotid bifurcation disease exists, with varying degrees of risk for each sub-group. With Duplex scanning we studied the carotid arteries of several asymptomatic populations: volunteers at a health fair, patients referred to our vascular laboratory because of cervical bruits or associated vascular disease, and the contralateral asymptomatic vessels in those patients who had previously undergone endarterectomy. Volunteers had an extremely low incidence of carotid disease, possibly reflecting a bias of more healthy individuals attending a health fair. The contralateral asymptomatic vessels and vessels in the hospital asymptomatic group both had similar disease, with mainly fibrous or calcific plaques. Occurrence of new carotid territory symptoms was low in each hospital group. However, there were more strokes in the territory of the contralateral asymptomatic vessels, suggesting a greater risk for these patients. Symptomatic vessels tend to have plaques that are heterogeneous and echolucent. Change in plaque morphology may eventually become the best predictor of stroke risk, but longer follow-up studies of plaque progression are needed. In the meantime, the characteristics of asymptomatic populations in carotid artery studies must be carefully defined.

Adult↗

PubMedDate not supplied

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.

Aged↗

PubMedDate not supplied

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.

Animals↗

PubMedDate not supplied

Femoral artery doppler signal analysis in lower limb ischaemia.

The functional significance of the iliac artery stenosis was assessed non invasively using femoral artery Doppler signals and a new method of blood velocity waveform quantification. This mathematical analysis provided an index, the Laplace Transform Damping (LTD), which was compared with Pulsatility Index (PI) of 263 limbs, in patients with iliac occlusive atherosclerosis was demonstrated by arteriogram and in normal volunteers. Normal LTD results ranged from 0.26 to 0.43 with detection of minor iliac stenosis (less than 50%) at 0.51 (0.38 to 0.63) and major stenosis (greater than 50%) at 0.83 (0.55 to 0.99). LTD was not affected by raised distal impedance associated with superficial femoral artery (SFA) occlusion. PI however was poor at predicting the severity of iliac lesions in the presence of SFA occlusion. LTD and PI specificities and sensitivities were examined using receiver operator curves. At a value of 0.6 LTD was more sensitive than PI in separating major from minor iliac stenoses and at 0.4 LTD separated normals from the early disease group with a sensitivity of 81% and specificity of 88%. This preliminary experience with Laplace Transform Damping analysis suggests that it will improve the assessment of iliac stenosis especially in the presence of femoro-popliteal disease.

Adult↗