[Electric thrombosis of the experimental aneurysm--effect of alteration in intraaneurysmal hemodynamics on thrombus formation and progress of thrombosis (author's transl)].

Electric thrombosis may be one of useful method to provide protection against re-bleeding from the intracranial aneurysm which cannot be obliterated by clipping or ligation of its neck without disturbing arterial circulation. However, a better method is required to make the aneurysm to be almost completely thrombosed within one or two hours and to avoide marked damage of its wall, dislodging of the formed thrombus and excessive thrombosis. In this report a method of electric thrombosis of the experimental aneurysm was studied, and effects of hematocrit value and alteration in intraaneurysmal hemodynamics on thrombus formation and progression of thrombosis were investigated. An aneurysm-like vein pouch of 6 to 9 mm in diameter and of 5 to 8 mm in height was made on the common carotid artery of the dog. One week later, patency of the "aneurysm" was confirmed on angiogram. An anodal electrode of a platinum needle of 0.2 mm in diameter was inserted into the "aneurysm" to place the tip of the needle approximately at the center of the sack. Two platinum plates of 3 mm in diameter and of 0.1 mm in thickness were used as the cathodes and were placed externnally on the aneurysm wall. Direct current of 3 mA was applied for 5 or 10 minutes, or current of 5 mA for 5 minutes. Intraaneurysmal pulsating jet and turbulent flows were reduced by occlusion or stenosis of the common carotid. Size of the thrombus immediately after passing current and further progress of thrombosis were evaluated on angiogram and also on plethysmogram of the "aneurysm". Hematocrit value of 45% or more was favorable in producing a thrombus. Although direct current of 3 or 5 mA was desirable to avoid injury of the "aneurysm" wall and to inhibit dislodging of the formed thrombus, only a small thrombus was produced around the anode. Simultaneous occlusion or stenosis of the carotid artery proximally to the "aneurysm" during application of the current markedly promoted thrombus formation. With current application for 5 minutes, 30 to 40% or more of "aneurysm" lumen was occupied by the thrombus in a half of the cases. When the thrombus had reached to approximately 40% of aneurysm "sack" 5 minutes after passing DC current, it progressed to 80% within the following one hour. The most favorable site of the anode for progression of thrombosis was the proximal wall (cardiac side) of "aneurysm". Proximal occlusion or stenosis of the carotid artery promoted remarkably also progress of thrombosis. Excessive thrombosis, dislodging or spontaneous resolution of the formed thrombus was not found throughout one month follow-up. Histologically, the thrombus was organized within one month and covered with the endothel extending from the parent artery.