Oxford screening programme for abdominal aortic aneurysm in men aged 65–74 years

ABSTRACTS James S. T. Yao, MD, Abstracts Section Editor

Correlation between the effects of aspirin damole on platelet f3nction and prevention hyperplasia in autologous vein grafts

and dipyriof intimal

Landymore RW, Karmazyn M, MacAulay MA, Sheridan B, Cameron CA. Can J Cardiol 1988;4:56-9. Researchers from the Departments of Surgery, Pathology, Hematology, and Pharmacology of Dalhousie University, Halifax, Nova Scotia, Canada, used a canine model to study the effects of aspirin and dipyridamole on intimal thickening in autogenous vein grafts. Fifty-four dogs were fed a 2% cholesterol diet for 1 week before and 6 weeks after bilateral femoral artery replacement grafting with autogenous jugular vein. The animals were stratified into three study groups. Twenty-one animals were controls receiving no aspirin or dipyridamole. Seventeen animals received daily doses of dipyridamole (2 mg/kg) and aspirin (30 mg/kg), whereas the remaining 16 animals received dipyridarnole (2 mg/kg) alone. Serum cholesterol, prothrombiu time, partial thromboplastin time, clotting time, plasma thromboxane B, (TxB,), and the metabolite of prostacyclin I, (6-keto PGF,,) were measured at various intervals in each group. Vein graft intimal hyperplasia was measured with a computerized microscope. Control explants showed marked intimal thickening (59 ? 6 pm) when compared with explants from either treatment group. The reduced amounts of intimal hyperplasia were comparable between the two treatment groups (dipyridamole group 26 * 2 pm) (aspirin and dipyridamole combination group 28 + 2 pm). Serum cholesterol rose significantly and similarly in all groups. Platelet counts were decreased in the group receiving both aspirin and dipyridamole, but other hematologic parameters remained unchanged. Measurements of the prostanoid metabolites TxB, and 6-keto PGF,, were unaffected by dipyridamole alone but were significantly decreasedin the group receiving combined drug therapy. The authors conclude that dipyridamole was as effective in reducing smooth muscle cell proliferation as the combination of aspirin and dipyridamole. Since the plasma prostanoid metabolites measured were unaffected by dipyridamole, it appears that the antiplatelet drug regimens studied reduce intimal thickening in autologous vein grafts by some other mechanism than by affecting the TxB,/6keto PGF,, ratio. Daniel Henry

Otiord eurysm

J. Reduy, MD Ford Hospital

screening programme for abdominal in men aged 65-74 years

aortic

an-

Collin J, Walton J, Araujo L, Lindsell D. Lancet 1988: 613-5. This prospective mass screening program attempted to identify men with an asymptomatic abdominal aortic an-

eurysm. All male patients (age 65 to 74 years) on the register of a large general group practice in the United Kingdom were invited to undergo physical examination of the aorta, abdominal ultrasonography, and ankle/arm blood pressure testing; 5 1.7% accepted the invitation and 426 total examinations were performed. Of the screened patients 5.9% had either an aortic or iliac aneurysm diagnosed by ultrasonography, although most were <4 cm in size. The clinical examination of the aorta was frequently inaccurate; only 10145 patients with suspected aortic aneurysms by physical examination had confirmation with ultrasonography. Patients with claudication or a reduced ankle/ brachial index had a greater prevalence (17.9% and 13.9%, respectively) of aneurysm than those with no symptoms or signs of occlusive disease (4.7%). There was a correlation between smoking and aneurysm detection, but no correlation was found between systemic hypertension and aneurysmal disease. The conclusion of the authors is that a simple screening program of older men identifies patients at high risk for asymptomatic aneurysms, which may occur initially with life-threatening rupture. However, the attempt to extrapolate these data to the entire population ignores the potential sampling error with this type of study. Presumably, patients who accepted the invitation for screening were a higher risk group than those who did not. Therefore the authors’ calculation that mass screening of all older men in the British Isles would result in identification of 52,500 men with aneurysms and would prevent 6000 unnecessary deaths may be overstated. However, this study does help clinicians determine which patients might benefit from screening aortic ultrasonography-older men who smoke and have evidence of arterial occlusivedisease.In addition, this study reemphasizesthat physical examination is inaccurate in assessingaortic size, particularly in obese men. Peter F. Lawrence, AiD Universityof Utah Medical

Epidural patients

Center

vs general anaesthesia and leg blood with occlusive atherosclerotic disease

flow in

Haljamaeh H, Frid I, Holm J, Akerstrom G. Eur J Vast Surg 1988;2:395-400. This study investigated differences in lower extremity blood flow when either epidural or general anesthetic was used during arterial reconstruction. Measurements were made in the leg contralateral to the vascular reconstructive procedure in 31 patients randomized to either epidural anesthesiawith mepivacaine or general anesthesiawith fentanyl and nitrous oxide. Calf blood flow was measured by venous occlusion plethysmography and skin blood flow was measured by laser Doppler. In addition, similar mea-’ surements were made in 24 nonvascular “control” patients in whom the type of anesthetic was also randomized. 601