The PO2 in the lumen and valve pockets of veins in 2 patients and 8 dogs was measured during streamline blood flow and in conditions of intermittent pulsatile flow. The blood within the valve pockets became rapidly hypoxic when undisturbed during streamline flow (i.e. when "static"), but the PO2 in the pockets rose to that of the lumenal blood when the column of venous blood was made to pulsate and so empty the valve pockets at short intervals. The observations suggest that the endothelium covering the valve cusps is entirely dependent on pocket or lumenal blood for its oxygen supply. The endothelium facing the pocket can therefore become hypoxic during non-pulsatile blood flow when that facing the lumen is adequately to oxygenated. Early thrombus formation was seen to develop on a valve cusp after only 2 h non-pulsatile flow. The demonstration that localized hypoxaemia occurs readily and can produce endothelial damage, in circumstances and situations where thrombi are commonly found to originate, is additional circumstantial evidence that hypoxia may trigger thrombogenesis.

As part of the Birmingham Community Aneurysm Screening Project, 3500 men aged 65-75 years from 20 urban general practices were invited for aortic ultrasonographic screening at their own general practitioner's surgery; 2669 (76.3 per cent) attended. Compliance rates varied between catchment areas, from 52.1 per cent for inner-city areas to 89.6 per cent for suburbs. Successful aortic imaging was achieved in 97.3 per cent of scans. Aortic diameter > 29 mm occurred in 219 patients (8.4 per cent) and 79 (3.0 per cent) with a diameter > 40 mm were referred for vascular surgical assessment; 140 patients with an aortic diameter of 29-40 mm are currently undergoing follow-up by serial ultrasonographic examinations at intervals of 3 months at their doctor's surgery. Risk factor analysis revealed ischaemic heart disease in 21.9 per cent of men with aneurysm, compared with 11.6 per cent in those without (P < 0.001); 18.3 per cent of men with aneurysm had had a previous myocardial infarction and 13.2 per cent had peripheral vascular disease, compared with 7.4 per cent (P < 0.001) and 8.0 per cent (P < 0.01) respectively of those without. No association was found between aneurysm and hypertension or diabetes. Community-based aortic screening is an inexpensive, effective method of diagnosis of aneurysm, with high compliance from the at-risk cohort of an urban population. Such screening programmes may help to reduce the mortality rate from aortic aneurysm rupture.

Of 21 limbs having successful femoropopliteal vein by‐pass grafts, 20 showed peripheral oedema 7 days after operation. Circumferential enlargement of more than 4.5 cm. was associated with thrombosis of the popliteal or tibial veins, whereas legs enlarging less than 1.5 cm. did not show radiological evidence of venous thrombosis. Venous thrombosis is less likely after surgery for intermittent claudication than for rest pain or gangrene of the toes. Distal anastomosis of the vein‐graft to the popliteal artery is more often accompanied by venous thrombosis than anastomosis above the knee‐joint.