Morphological changes of intracranial pressure quantifies vasodilatory effect of verapamil to treat cerebral vasospasm

Abstract

Introduction: After aneurysmal subarachnoid hemorrhage (SAH), both proximal and distal cerebral vasospasm can contribute to the development of delayed cerebral ischemia. Intra-arterial (IA) vasodilators are a mainstay of treatment for distal arterial vasospasm, but no methods of assessing the efficacy of interventions in real time have been established.

Objective: To introduce a new method for continuous intraprocedural assessment of endovascular treatment for cerebral vasospasm.

Methods: The premise of our approach was that distal cerebral arterial changes induce a consistent pattern in the morphological changes of intracranial pressure (ICP) pulse. This premise was demonstrated using a published algorithm in previous papers. In this study, we applied the algorithm to calculate the likelihood of cerebral vasodilation (VDI) and cerebral vasoconstriction (VCI) from intraprocedural ICP signals that are synchronized with injection of the IA vasodilator, verapamil. Cerebral blood flow velocities (CBFVs) on bilateral cerebral arteries were studied before and after IA therapy.

Results: 192 recordings of patients with SAH were reviewed, and 27 recordings had high-quality ICP waveforms. The VCI was significantly lower after the first verapamil injection (0.47±0.017) than VCI at baseline (0.49±0.020, p<0.001). A larger dose of injected verapamil resulted in a larger and longer VDI increase. CBFV of the middle cerebral artery increases across the days before the injection of verapamil and decreases after IA therapy.

Conclusion: This study provides preliminary validation of an algorithm for continuous assessment of distal cerebral arterial changes in response to IA vasodilator infusion in patients with vasospasm and aneurysmal SAH.

Keywords: cerebral vasospasm; endovascular treatment; intra-arterial treatment; subarachnoid hemorrhage; vasodilator.

Fig 1.

A) The percentage of verapamil injection in each artery. B) The anatomy of the arteries that has endovascular treatment in our study. ACA: anterior cerebral artery; MCA: middle cerebral artery; ICA: internal carotid; ECA: external carotid artery; BA: basilar artery; CCA: common carotid artery; VERT: vertebral artery.

Fig 2.

An example VDI, VCI changes after verapamil injection. The three vertical, dot lines represent three injections of verapamil medicine. The four small charts in the upper panel represent dominant ICP pulses at baseline (6 dominant pulses that were selected as baseline pulses to be compared to for VCI and VDI calculation), after the 1^st injection, after the 2^nd injection, and after the 3^rd injection. ICP: intracranial pressure, VCI: vasoconstriction index, VDI: vasodilation index.

Fig 3.

Mean values of VCI, VDI, ICP and ABP before and after injection of verapamil medicine. ICP: intracranial pressure, VCI: vasoconstriction index, VDI: vasodilation index. ABP: arterial blood pressure. P<0.05 was considered to be significant. * means p<0.05; ** means p<0.01.

Fig 4.

VDI changes along time with injection of different dosage. Time 0 refers to the time point when the verapamil was first injected. VDI: vasodilation index.