Sufficient Collaterals Research Articles

Indications for extra-intracranial bypass surgery. New orientation after the Toronto Bypass Study based on angiographic and non-invasive ultrasound flow measurements.

Angiographic and flow measurement results in 18 cases, who underwent extra-intracranial bypass surgery, are presented. The method was the Mavis ultrasound technique. Patients with unilateral internal carotid artery (ICA) occlusion and additional contralateral ICA stenosis or occlusion had a permanent cerebral blood flow (CBF) increase as a consequence of the anastomosis. On the contrary, patients without contralateral flow impairment or with good spontaneous extra-intracranial anastomosis did not have a real CBF improvement but only a temporary flow increase on the anastomotic side with comparable flow decrease in the contralateral ICA. The so-called Toronto Bypass Study was designed to evaluate the effectiveness of extra-intracranial bypass surgery for stroke prevention but it did not prove its effectiveness in this regard. Intentionally it did not put or answer the question of possible haemodynamic benefit for special subgroups of patients with cerebrovascular occlusive disease. Our results suggest such a haemodynamic benefit, and in consequence an indication for bypass treatment may be given in cases with ICA occlusion and additional contralateral flow impairment and without sufficient spontaneous collateralization. The question of a stroke preventing effect in this special subgroup should be answered by another controlled study. But this will be almost impossible to realize because--as a consequence of the Toronto study--at least in our country almost no further patients are transferred to the neurosurgeon for possible bypass surgery.

Peripheral right coronary artery pressure distal to the ligation: effect of augmented left circumflex coronary artery pressure.

The ligature of right coronary artery near its origin produced low distal right coronary artery pressure, which showed gradual increase day by day, reaching maximum level (70% of the aortic pressure) in 8 postoperative days.The trial to produce rapid increase of the distal right coronary pressure by augmenting the left circumflex coronary pressure by means of roller pump was carried out in normal dogs. But the increase of the distal right coronary artery pressure was only several millimeters mercury. The pressure augmentation of 2 hours in the left side, therefore, could not produce sufficient collaterals from left to right.