Balloon embolectomy catheters in small arteries: a technique to prevent excessive shear forces.

Balloon embolectomy catheters were studied in canine common carotid arteries (2 to 3 mm) in vitro to evaluate a technique of preventing excessive shear forces and to examine the effect of blood within the lumen. Each balloon was studied at 25, 75, 125, or 150 mm Hg lateral wall pressure. Shear forces were recorded in 16 vessels when the balloons were distended before catheter withdrawal, and these data were compared with forces recorded when the balloons were distended during catheter withdrawal. Results showed that distention of the balloon during withdrawal reduced shear forces 43.8% to 55.8% (p less than 0.05). In other experiments shear forces were recorded when the lumen was lubricated with heparinized saline solution, and these were compared with forces recorded when the lumen was lubricated with heparinized whole blood. The presence of blood in the lumen reduced shear forces 23.4% to 52.9% (p less than 0.05). From these studies it is recommended that during embolectomy in patients the balloons be distended during the first half centimeter or centimeter of catheter withdrawal to prevent excessive shear forces and that residual blood in the vessel lumen proximal to the point of embolic obstruction be accepted without concern, provided adequate heparinization has been achieved.