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Biomedical subjects

R G Gosling

Publications and source records attributed to R G Gosling.

At least 91 records · Page 5Linked to original sources
PubMed1979

Disease at the carotid bifurcation: diagnosis by Doppler ultrasound imaging.

A non-invasive method for visualising the carotid bifurcation using continuous-wave Doppler-shift ultrasound and spectral analysis is described. The system is directional so that arteries can be visualised without interference by signals from adjacent veins. The technique uses a transducer attached to a position-sensing arm so that the position of arterial flow-velocities can be translated onto a storage oscilloscope. A two dimensional image of the carotid bifurcation is formed by moving the transducer along the length of each vessel while repeatedly scanning across the vessel lumen. The clinical application of this technique is illustrated by some specific cases.

Adult↗
PubMed1977

Screening for carotid junction disease by spectral analysis of Doppler signals.

The established test for disease in the internal carotid artery using continuous wave Doppler is to listen for flow velocity changes over the supraorbital artery with ipsilateral temporal (or facial) artery compression. This is only reliable when there is a reduction in mean pressure (and flow) distal to disease in the internal carotid artery, ie reduction of lumen diameter by more than 85%. In this study, 101 vessel segments (48 with disease at the carotid junction, 53 normal) were compared with the results of angiography. Seven gave a positive temporal artery occlusion test, all of which showed severe disease. However, spectral analysis of the Doppler signals from supraorbital and common carotid arteries showed sonagram changes both with ageing and with disease. In particular, the ratio of primary peak (A) to secondary peak (B) in systole falls, the A/B ratio being lower in disease than in health. At A/B ratios less than 1.05 there was an 88% probability of disease at the carotid junction. 36/48 (75%) diseased junctions were detected, including almost all major lesions. The method did not so reliably detect small lesions (less than 2 mm plaques, less than 60% lumen diameter stenosis, and 'minimal atheroma'). In 5/53 normal junctions the A/B ratio was in the disease range. Scanning the carotid junction for turbulence yielded additional information in some cases.

Adolescent↗
PubMed1977

Effect of oral contraceptives on resting blood flow in the leg.

Resting blood flow in the leg was measured twice per week by venous occlusion plethysmography, for two or more menstrual cycles in 11 normal female volunteers, 5 of whom were taking an oral contraceptive. Both groups showed a wide range of resting flow, with lowest values doubling or occasionally nearly trebling in any one menstrual cycle. In 1 subject a repeatable cyclic variation was found. The mean resting flow of the group taking oral contraceptives was found to be lower (0.1 less than P less than 0.2) and the range of flow values over the menstrual cycle smaller, than those of the subjects not using the pill. The lower flow values found for subjects on the pill suggests a possible mechanism linking use of oral contraceptives with the occurrence of venous thrombosis. However venous distensibilities estimated from plethysmographic observations indicate that the thrombogenic effect of low flow values may be offset by decreased distensibility, and hence it may be possible to maintain normal blood velocities.

Adult↗
PubMed1976

Anomalous iliac compliance in children with a single umbilical artery.

Arterial compliance (C) has been measured in 18 children known to have had a single umbilical artery at birth. Non-invasive ultrasonic Doppler techniques were used to measure C for the aorta, iliac, and leg arteries. Anomalous compliance was found between the two iliac vessels, and it is suggested that this is the result of haemodynamic stress-induced changes during development. The demonstration that the form of large arteries may be changed by altered haemodynamic stress and that their physiological function is thus affected, may have important implications in the pathogenesis of degenerative disease.

Aorta, Abdominal↗
PubMed1975

The dynamic and static elastic response of the abdominal aorta of the dog.

The dynamic and static elastic response of the abdominal aorta was studied in beagle dogs of similar age and weight. The dynamic response was measured in situ by means of an optical transmission wedge resting on the exposed vessel to record the pulsatile changes in wall displacement and the pressure pulse recorded at the same site via a hypodermic needle. The static response was recorded (1) in situ by observing the change in radius which occurred with a change in the mean blood pressure, (2) post mortem using both transmission wedge and radiographic techniques. The change in radius (deltaR) for a change in pressure (deltaP=20 mm Hg[2.67kPa]) was calculated for both the dynamic and static cases. It was found that the aorta was stiffer for the dynamic case, the extent of the stiffening being dependent on the mean pressure. At pressures less than 80 mm Hg (10.64 kPa) the dynamic/static deltaR ratio was 1.8 decreasing to 1.1 at 160 mm Hg (21.28 kPa). This behaviour is interpreted in terms of smooth muscle relaxation and the subsequent transference of circumferential tension to collagen.

Animals↗