A preliminary report of experimental and clinical observations upon cervical carotid artery blood flow

Mechanism of enlargement of major cerebral collateral arteries in rabbits

Major cerebral collateral arteries enlarge following bilateral ligation of the common and internal carotid arteries. The purpose of this investigation was to determine the relative contribution of cellular hypertrophy versus cellular hyperplasia to this vessel change in a morphometric analysis as well as the functional properties of remodeled vessels in an in vitro study. We assessed cell number and vessel dimensions by morphometric analysis of 16 perfusion-fixed rabbit basilar arteries. Results demonstrated significant increases in luminal diameter from 761 to 946 microns (p less than 0.01), medial cross-sectional area from 5.1 x 10(4) to 7.6 x 10(4) micron2 (p less than 0.005), smooth muscle cell volume from 9.19 x 10(5) to 1.44 x 10(6) micron3 (p less than 0.0005), and overall arterial length from 17.41 to 20.36 mm (p less than 0.005) in basilar arteries from the eight ligated rabbits compared with the eight sham-operated controls. Smooth muscle cell volume fraction and cell numerical density were unchanged whereas the number of cells per unit length of artery was increased significantly from 21.5 to 31.0 cells/micron (p less than 0.05). These data indicate that smooth muscle cell hyperplasia rather than hypertrophy contributes to increases in vessel mass. Functional properties of the basilar arteries from 10 ligated and 10 normal control rabbits were analyzed in vitro. Results showed increased contraction to potassium chloride (approximately 74%) (p less than 0.01) and increased sensitivity of smooth muscle to acetylcholine (p less than 0.05) while maximal relaxation was the same as control in the ligated animals.(ABSTRACT TRUNCATED AT 250 WORDS)

The hemodynamic effect of bilateral carotid artery ligation and the morphometry of the main communicating circuit in normotensive and spontaneously hypertensive rats

After reducing the number of patent conduit arteries to the brain by bilateral ligation of the carotid artery, the percentage decrease in blood pressure from the aorta to the internal carotid artery distal to the ligation was larger in spontaneously hypertensive rats than in normotensive rats. The pressure drop corresponded to the degree of hypertension as well as to morphometrically determined structural arterial alteration in the main communicating circuit, i.e. larger media to internal radius ratio and smaller internal radius in the posterior communicating arteries, the proximal part of the posterior cerebral arteries, the basilar artery and the vertebral arteries. The discrepancy between the sum of the luminal cross sectional areas of the communicating circuit and the luminal areas of the ligated conduit arteries was larger in the hypertensive than in the normotensive rats. It is to be expected that occlusion of conduit arteries to the brain will have a larger impact on the cerebral arterial perfusion pressure head in the presence of such hypertensive structural alterations known to increase flow resistance.

A combined technique for treating certain aneurysms of the anterior communicating artery

✓ Thirty-one patients with aneurysms of the anterior communicating artery that filled from both sides during carotid arteriography were treated by a combined operative procedure consisting of clip-ligation of one proximal anterior cerebral artery followed by gradual occlusion of the opposite common carotid artery with a Crutchfield clamp. In 14 patients, intravascular pressure recordings in the carotid vessels in the neck were obtained both before and immediately after ligation of the anterior cerebral artery. Before ligation the average intravascular pressure reduction was 55%, while after ligation the average reduction was 71%. Of the 31 patients, 22 have had good results and no recurrent hemorrhage. Nine patients died, four from recurrent hemorrhage. Follow-up carotid arteriography in nine patients showed the aneurysm obliterated in six, smaller in one, and unchanged in two. The results of this study indicate that treatment of certain anterior communicating aneurysms by the combined operative approach described is useful.

Angiographic investigation of patients with transient ischaemic attacks

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