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An ECG-triggered venous occlusion Plethysmographic method to provide an index of arterial inflow, has been used in 10 patients with angiographic confirmed intermittent claudication. The differential quotient of the Plethysmographic arterial pulse has been used to provide an index of pulse wave velocity. The effect of cinnarizine, a drug which acts probably by inhibiting the calcium influx into vascular smooth muscle cells, was measured after three and seven days of administration. In this trial cinnarizine increased blood flow to the lower limb following exercise.

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.

The term ‘cerebral activating drugs’ is used for the title of this chapter as a convenient way to embrace a wide variety of drugs which have been used in attempts to improve cerebral function in old age. Such drugs include vasodilators, drugs influencing cerebral metabolism, stimulants and drugs which are claimed to improve the flow of blood in the cerebral microcirculation by virtue of actions on blood viscosity, red cell deformability, or one or more biochemical effects at the cellular level.

The liver loses weight from 50 years onwards (Bean 1926; Rossle and Roulet 1932; Boyd 1933; Meyer et al. 1964; Thompson and Williams 1965). Racial and environmental differences occur in this age-related loss of liver weight (Tauchi and Sato 1975). Liver weight correlates with total body weight (Thompson and Williams 1965).