R. N. Baird

Percutaneous transluminal angioplasty for lower limb ischaemia

Percutaneous transluminal angioplasty (PTA) is increasingly performed for lower limb ischaemia of all severities, despite the absence of controlled data demonstrating its efficacy. The aim of this study was to examine the indications and outcome for lower limb ischaemia over a 16‐year period.Forty successful percutaneous transluminal angioplasties (PTA) were performed in the iliac and femoropopliteal segments of 33 patients with lower limb ischaemia. There was immediate symptomatic relief in 37 limbs (92 per cent) although 7 relapsed and 5 patients required reconstructive arterial surgery within a month of PTA. Objective testing showed that the longer term relapse rate (median follow-up 12 months) was low (10 per cent). Despite a significant incidence of early complications and relapse, PTA provided a good long term result in the majority of patients treated.

Carotid artery disease: A prospective evaluation of pulsed doppler imaging

Abstract Ultrasonic imaging of the carotid artery bifurcation using a 30 channel pulsed Doppler system has been studied in a prospective trial. The results were compared to X-ray contrast angiography. Ninety per cent of the lesions of less than 50% were detected, as were all total occlusions of the internal carotid artery. The overall sensitivity was 93% and specificity 100%. Lateral ultrasonic scans were important in detecting lesions of less than 50% stenosis providing the diagnostic information in 48% of these vessels. The ability to identify both low and high grade stenoses with this system provides a basis for routine screening of patients with suspected carotid disease.

Physiological interpretation of Doppler shift waveforms: the femorodistal segment in combined disease

A new method is presented for assessing the femorodistal segment in multisegmental arterial disease, using the Laplace transform technique of Doppler waveform analysis. Blood velocity/time waveforms were obtained at femoral and ankle levels in three groups of limbs--50 without arterial disease, 12 with isolated aortoiliac stenoses, and 32 with femoropopliteal occlusions, with and without proximal disease. The waveforms were analysed for Laplace transform and pulsatility index values. The omega 0 coefficients of the Laplace transform analysis at femoral and ankle levels were compared in each subject, as the omega 0 gradient (femoral/ankle omega 0): and pulsatility index damping factor (femoral/ankle P1) was also calculated. The omega 0 gradient was shown to detect femoropopliteal occlusion in the presence of multisegmental arterial disease and to give some indication of its haemodynamic significance. The diagnostic accuracy of the omega 0 gradient was superior to that of pulsatility index damping factor. When combined with its existing ability to detect aortoiliac stenosis, this new application of the Laplace transform method offers the possibility both of a system for complete localisation of significant arterial lesions, and potential for follow-up of vascular surgical procedures in the lower limb, from two simple Doppler recordings.

Variability and reproducibility of arterial Doppler waveforms

The variability and reproducibility of arterial Doppler waveforms are influenced by factors such as operator experience, physiological changes in the patient, and the type of Doppler processing system. Some aspects of these were studied using Laplace transform analysis of waveforms from the femoral and posterior tibial arteries of normal subjects and arteriopaths. Five consecutive waveforms were obtained from the femoral and posterior tibial arteries of normal subjects during about 1 hr of supine rest. Group 1 (n = 20) was studied 9 months before Group 2 (n = 11), early in the operators experience of waveform recording. Variability (root mean square) of femoral and posterior Laplace delta decreased from 16.9 to 12.5%, and 23.3 to 17.9% respectively (P less than 0.05 in each case). In arteriopaths (n = 8) there was a trend to more variable results at femoral level (only significant in the case of Laplace omega 0 - P less than 0.05), while posterior tibial results tended to be less variable. Normal subjects examined in the longer term (n = 4), with a mean interval of 28 days between recordings, did not show significantly greater variability than those examined over 1 hr. There was no significant difference in variability of results in normal subjects (n = 30) using instantaneous average Doppler processing compared with maximum frequency processing, except in the case of posterior tibial Laplace omega 0 (maximum frequency more variable - P less than 0.05).

Femoral Artery Doppler Waveform Analysis in the Assessment of Combined Iliac and Femoral Artery Disease

The functional assessment of incomplete stenosis of the iliac arteries using Doppler ultrasound has developed because routine arteriography may not identify the severity and extent of the occlusive atherosclerosis. The results of both proximal (1, 2) and distal (3) reconstruction can be poor and this has led to the search for better methods of preoperative assessment.

Ultrasonic Doppler Scanning and B Mode Imaging of the Carotic Artery

Cerebral ischaemic attacks may be due to carotid bifurcation disease (3, 4, 6, 10) from emboli arising from atheromatous ulcers or haemodynamically significant stenosis or occlusion of the internal carotid artery (ICA). The need to determine the presence and nature of carotid lesions has been increased with the success of carotid endarterectomy in preventing stroke (8). While preoperative evaluation requires angiography for full assessment of extra- and intracranial vessels, it is not suitable to screen all patients with suspected cervical carotid vessel disease, due to the associated risks (7).