Anticoagulants are a class of drugs that work to prevent the coagulation (clotting) of blood.

Such substances occur naturally in leeches and blood-sucking insects. A group of pharmaceuticals called anticoagulants can be used as an injection into human beings as a medication for thrombotic disorders.

Oral anticoagulants are also available. Some anticoagulants are used in medical equipment, such as test tubes, blood transfusion bags, and renal dialysis equipment.

A comprehensive knowledge of novel anticoagulants is an important part of current neurosurgical practice. While warfarin, heparin and its low molecular weight derivative, enoxaparin, have formed the mainstay of treatment for atrial fibrillation, valvular heart disease and the prevention of venous thromboembolism for over 30 years 1) , new agents have recently been approved that promise to revolutionize the treatment of these conditions. There are compelling medical reasons driving the adoption of these agents and they will have an important impact on neurosurgical practice 2).

see Heparin.

Perioperative anticoagulant prophylaxis for postoperative venous thromboembolism (VTE) in neurosurgical patients has not gained wide acceptance due to the fear of intracranial bleeding. Physical methods give a worthwhile reduction of postoperative VTE but there still remains a substantial residual incidence. In other clinical indications, low molecular weight heparins have proven to be effective for prophylaxis of VTE when administered postoperatively, with the advantage of no bleeding enhancement during surgery.

Anticoagulation after ischemic stroke was a topic of major controversy for decades until a series of Randomized controlled trials consistently showed no net benefit of heparin or warfarin compared with aspirin 3) 4).

see Anticoagulation in glioblastoma.

While oral anticoagulation (OAC) is universally indicated for patients with mechanical heart valves (MHVs), OAC resumption following anticoagulant-associated intracerebral hemorrhage (ICH) is an area of uncertainty.

A cross-sectional survey was disseminated to North American members of the American Association of Neurological Surgeons and the International Society for Thrombosis and Haemostasis. Demographic factors, as well as a clinical scenario with 14 modifiable clinical risk factors were included in the survey.

504 physicians completed the survey (response rate 34.3%). Majority of participants were affiliated with academic centres, and managed ≤10 ICH patients with MHV per year. There was wide distribution in response in optimal timing for OAC resumption following an ICH: 59% and 60% preferred to re-start OAC between 3 and 14 days following the hemorrhagic event (median of 6-7 days). Smaller hemorrhages (<30cm2). CHADS2 score ≥2, concomitant venous thromboembolism, mitral valve prosthesis, caged-ball valves and multiple valves prompted earlier OAC resumption.

Wide variation in the current practice of neurosurgeons and thrombosis specialists exist when they encounter patients with ICH and MHV, though decisions were influenced by patient- and valve-related factors. As our observed variation likely reflects the immense gap in current evidence, prospective randomized trials in this population are therefore urgently needed 5).

Verma AK. Dabigatran etexilate: A new thrombin inhibitor. Med J Aust. 2010;192:407–12.
Dwyer CM, Damodaran O, Heckelmann M, Sheridan MM. What neurosurgeons need to know about dabigatran etexilate (pradax(®)/pradaxa(®)/prazaxa(®). Asian J Neurosurg. 2015 Apr-Jun;10(2):66-8. doi: 10.4103/1793-5482.144156. PubMed PMID: 25972932; PubMed Central PMCID: PMC4421970.
PA Sandercock, C Counsell, AK Kamal Anticoagulants for acute ischaemic stroke Cochrane Database Syst Rev (2008) CD000024.
PA Sandercock, LM Gibson, M Liu Anticoagulants for preventing recurrence following presumed non-cardioembolic ischaemic stroke or transient ischaemic attack Cochrane Database Syst Rev (2009) CD000248.
AlKherayf F, Xu Y, Westwick H, Moldovan ID, Wells PS. Timing of anticoagulant re-initiation following intracerebral hemorrhage in mechanical heart valves: Survey of neurosurgeons and thrombosis experts. Clin Neurol Neurosurg. 2017 Jan 16;154:23-27. doi: 10.1016/j.clineuro.2017.01.006. [Epub ahead of print] PubMed PMID: 28103532.
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