Critical Pressure for Arterial Wall Rupture in Major Human Cerebral Arteries

Background and Purpose Intracranial bleeding is linked to hemodynamic stress factors, such as hypertension. However, there are no studies that tested the breaking pressure of normal large cerebral arteries in humans. Methods The brains of 10 cadavers (age, 4714 years; 9 men) were harvested within 48 hours postmortem for 31 segments of the main intracranial arteries. After careful microsurgical preparation, the vessels were pressurized with saline and observed until they ruptured. Results Vessel diameters averaged 2.6 +/- 0.3 mm (range, 1.2-4.3 mm). The average rupture pressure was 2.21 +/- 0.59 atm (range, 1.13-4.3 atm) and decreased with age at -0.025 atm/y (R-2=40%; P<0.0002). The maximum diameter distention at rupture was 30 +/- 9% (13%-52%), which also decreased with age (-0.5%/y; R-2=78%; P<0.00001). Neither the rupture pressure nor the maximum distention showed significant dependence on the resting vessel diameter. No significant dependencies were found on the vessel origin, vascular configuration, direction of the rupture, or the presence of minor coexisting pathology. Conclusions Human cerebral arterial wall breaks only at extremely high intravascular pressures, exceeding several times the highest observed systolic blood pressure, even accounting for age trends. Systolic hypertension alone may not be sufficient to cause intracranial hemorrhage, and there may be additional contributing factors.