▶️Adenosine alters electrical conduction at the atrioventricular (AV) node and has a negative chronotropic effect on the sinoatrial node.
▶️Adenosine acts on cardiac A1 receptors to reduce cAMP activity, which decreases inward calcium conductance and diminishes pacemaker current, resulting in bradycardia, AV nodal blockade, and sinus pauses.
▶️It has a very short half-life time (less than 10 seconds) and is rapidly taken up by the vascular endothelium and erythrocytes.
▶️The effect on heart rate is seen within 10 to 20 seconds after administration
▶️ There is a relative hypotension period, 1 minute after asystole
▶️Multiple doses are usually required for very large and complex aneurysms to obtain repeated episodes of asystole
▶️ Bebawy et al. recommended an initial dose of between 0.3 and 0.4 mg/kg ideal body weight (IBW)
▶️ Powers et al. gave a standard 6 mg dose initially escalated to 6 mg more than the previous dose (e.g. 6 mg, 12 mg, 18 mg, 24 mg ; repeating the dose as often as every 1 to 2 minutes) until 30 to 40 seconds of asystole was reached.
▶️ Guinn NR et al reported the median dose of intravenous adenosine resulting in bradycardia greater than 30 seconds was 30 mg. The median dose of adenosine resulting in hypotension greater than 30 seconds was 15 mg, and greater than 60 seconds was 30 mg
▶️Luostarien et al. reported that the median dose for a single bolus was 12 (6–18) mg, whereas the median total dose for multiple boluses was 27 (18–89) mg
▶️ Hypotension ( most often transient , sometimes requiring vasopressors), atrial fibrillation etc were reported as side effects
▶️ Adenosine-induced flow arrest briefly reduces cerebral perfusion pressure and reduces the turgor of the aneurysm, thereby facilitating the clip ligation
▶️ The adenosine dose will achieve approximately 45 seconds of controlled systemic hypotension and a bloodless surgical field.
▶️ Periods of flow arrest have to be carefully coordinated with the surgeon such that necessary working time is available for aneurysm dissection and clip placement
Reference: Adenosine-Induced Transient Asystole
Gavin W. Britz, Methodist Debakey Cardiovasc J. 2014
Oct-Dec; 10(4): 220–223.
Adenosine-induced transient asystole for intracranial aneurysm surgery: a retrospective review. Guinn NR, et al. J Neurosurg Anesthesiol. 2011.
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