Recent studies have shown potential benefit of UFH in preventing delayed neurologic deficit associated with aSAH.
UFH is the most negatively charged biological molecule known and can interfere with functioning of positively charged molecules. It has been documented to interact with over 100 proteins. IL, cytokines, receptors on endothelial cells are positively charged, and can be targeted by heparin.
Heparin has strong anti-inflammatory effects- binding to cell-surface glycosaminoglycans, preventing WBC migration, direct binding to chemokines and cytokines and inhibition of intracellular NF-κB. Heparin can also modulate endothelin-1 activity and scavenge free radicals and upregulate superoxide dismutase. Low-dose IV heparin provides anticoagulation effects, countering effects of SAH-induced microthrombi.
Recent study published in Journal of Neurosurgery used the following protocol for low-dose IV heparin:
Heparin 10-12 U/Kg/hr, start 12h after aneurysm treatment, until day 14 post-ictus, with routine PTT monitoring ensuring significant anticoagulation was not reached
Study was retrospective, non-randomized, with modest sample size, and suggests that the protocol is safe and has the potnetial to reduce cognitive outcomes in patients with aSAH. See table below for results of the study:
Bottom line: Not enough evidence to change practice, but promising. Await the results of ASTROH Trial (aSAH Trial Randomizing Heparin) (ongoing Phase 2) for further clarification.
James, R., Khattar, N., Aljuboori, Z., Page, P., Shao, E., Carter, L., Meyer, K., Daniels, M., Craycroft, J., Gaughen, J., Chaudry, M., Rai, S., Everhart, D. and Simard, J. (2018). Continuous infusion of low-dose unfractionated heparin after aneurysmal subarachnoid hemorrhage: a preliminary study of cognitive outcomes. Journal of Neurosurgery, pp.1-8.