Extrinsic sinus nodal dysfunction

Extrinsic sinus nodal dysfunction

Extrinsic mechanisms of sinus node dysfunction could be drug effects or due to autonomic influences. The important drugs which could suppress sinus node function are beta blockers, non-dihydropyridine calcium channel blockers like verapamil and diltiazem, digoxin, clonidine, methyldopa, class IA, IC and III antiarrhythmic agents and lithium.

Autonomic influences causing sinus node dysfunction are excessive vagal tone which can result in sudden cardiac arrest, carotid sinus hypersensitivity, vasovagal syncope and athlete’s bradycardia or bradycardia in well trained athletes.