Inducing transient circulatory arrest for trans-arterial embolization of intracranial arteriovenous malformations using adenosine-estimated dose injection technique: An anesthetists’ perspective and experience with three cases

Dear Editor, Adenosine has been used for inducing temporary cardiac standstill to aid in endovascular embolization of certain technically challenging intracranial arteriovenous malformations (AVMs), specifically high-flow ones. This technique was first demonstrated in 1999[1]; thereafter, multiple case reports have been published, which have used a wide dose range, viz: 18–90 mg.[2,3] There is no single consensus on its safe and effective dose. We describe our experience of using a single, fixed dose of adenosine, in three patients with AVM [Table 1 and Figure 1]; the complications faced, and the precautions and anesthetic techniques employed.Table 1: Summary of the three casesFigure 1: Axial T1-weighted MRI with contrast showing dilated cerebral veins and superior sagittal sinus, with AVM nidus enhancement and irregular hyperintense subacute hemorrhage in the left frontoparietal region (preoperative CET1W MRI of case 1)During pre-anesthetic check-ups, patients with severe (>80%) left main coronary artery stenosis, severe multivessel coronary artery disease (three vessels or grafts with >80% stenosis), AV conduction defects, or pacemakers and severe reactive airway disease (i.e. requiring hospitalization in last six months and active wheezing) were excluded. Inside the angiography suite, all patients were subjected to standard American Society of Anaesthesiologists (ASA) monitoring, invasive arterial blood pressure (ABP) monitoring, and central venous access in the left subclavian vein. General anesthesia, with intravenous glycopyrrolate 10 μg/kg, fentanyl 2 μg/kg, and propofol (dose titrated to loss of verbal response) and rocuronium 0.6 mg/kg, was used. The trachea was intubated with appropriate-sized cuffed endotracheal tube. Anesthesia was maintained with propofol target-controlled infusion, rocuronium infusion at 10 μg/kg/min, and sevoflurane (MAC <0.5). The neurointerventionist accessed the right common femoral artery to reach the arterial feeder (angiography guided) and planned to deposit NBCA glue/coils into the AVM. At this step, when flow arrest was requested, a pre-calculated dose of adenosine – 0.6 mg/kg – was injected through a central venous catheter and flushed. This resulted in asystole for 30–35 seconds and another 12–18 seconds of MAP <30 mm Hg from baseline. The success of glue/coil deposition was confirmed angiographically [Figure 2]. Muscle relaxation was reversed with sugammadex 2 mg/kg. Patients were discharged after 72 hours of observation in the ICU, with advice to continue physiotherapy. Six months follow-up revealed significant improvement of motor power in all patients.Figure 2: (a and b): Pre [A] and Post [B] operative catheter angiography of case 1 showing dilated middle cerebral artery feeding AVM and dilated draining cortical vein to superior sagittal sinusOur experience led us to the following conclusions: Careful patient selection, keeping contraindications of adenosine in mind,[4] is mandatory. Utmost vigilance and appropriate precautions are necessary, to prevent and treat adverse events. We used standard ASA (ECG lead II and V5) and invasive monitors (ABP), central venous access, and all resuscitative measures – emergency drugs and defibrillator. There is no specified dose in literature, which is labeled safe and effective for this purpose. Existing reports show usage of doses ranging from 18–90 mg, divided into increasing boluses, starting at 0.3–0.4 mg/kg.[2,3] Adenosine causes approximately 1 mg/sec of asystole,[3] and the duration necessary for successful aneurysmal ligation is around 30 seconds. Using repeated boluses is not free of risks, as administering repeat doses before complete haemodynamic recovery may lead to prolonged asystole and bradycardia.[5] We used an optimally safe, fixed dose of adenosine; 0.6 mg/kg ideal body weight, which lasted long enough (30–35 seconds) for successful endovascular embolization, without the requirement of multiple boluses. However, the formation of standardized recommendations requires large-scale studies, which may help us better utilize this efficacious technique. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.