Background and aim When a cerebral embolism occurs, pressure gradients in the arteries between sites proximal and distal to the embolus exert hydromechanical forces that push the embolus distally, and potentially affect successful revascularization during clot removal. We investigated the relationships between blood pressures that occur immediately distal and proximal to the embolus, systemic blood pressure and clinical variables.

Methods 36 patients with embolism of the internal carotid artery (13 patients) or the proximal middle cerebral artery (23 patients) were treated using intra-arterial thrombolysis. The mean blood pressure (MBP) at the sites proximal (proximal MBP) and distal (distal MBP) to the embolus was measured with a microcatheter. Simultaneously, the systemic MBP was recorded by cuff measurement.

Results Proximal, distal and systemic MBPs (mean±SD) were 95.2±13.2 mm Hg, 35.9±13.5 mm Hg and 98.2±12.2 mm Hg, respectively. The proximal MBP was significantly higher in the patients with systemic MBP≥100 mm Hg than those with systemic MBP<100 mm Hg (p<0.05). The distal MBP showed no difference between the high and normal systemic MBP groups.

Conclusions Higher systemic blood pressure produced stronger hydromechanical forces on the clot, forming a proximal–distal blood pressure gradient across the clot. The stronger hydromechanical force could result in higher compaction of the clot, thus making it more difficult to remove.