Tachyarrhythmias Antiarrhythmic drugs –Vaughan-Williams Classification –Drugs divided according to EP effects on cells –All are negatively inotropic –Can also be pro-arrhythmic
Tachyarrhythmias Class I –Impede Na transport across cell membrane –Ia increase AP duration eg quinidine, disopyramide, procainamide –Ib shorten AP duration eg lignocaine, mexilitene, propafenone –Ic little effect on AP eg flecainide
Tachyarrhythmias Class II –Interfere with effects of SNS on the heart eg beta blockers Class III –Prolong AP duration but do not effect initial Na dependent phase eg sotalol, amiodarone Class IV –Antagonise Ca transport across cell membrane –SA and AV node particularly susceptible eg verapamil, diltiazem
AV Nodal block [Class II –Interfere with effects of SNS on the heart eg beta blockers] Class III –Prolong AP duration but do not effect initial Na dependent phase eg sotalol, amiodarone Class IV –Antagonise Ca transport across cell membrane –SA and AV node particularly susceptible eg verapamil, diltiazem Adenosine –Specific AV nodal block
Atrial Flutter: RFA vs AA drugs JACC2000;35:1898 prospective, randomised – 61 pts SR at 21 months:36%AAD vs 80% RFA Rehospitalised:63% AAD vs 22% RFA AF:53% AAD vs 29% RFA QOL:no change AAD improvement RFA
AV node disease Complete (3rd degree) heart block
Bradyarrhythmias AV node disease –1st degree; prolonged PR interval –2nd degree; Mobitz type I (Wenckebach); increasing PR interval then non-conducted P wave –2nd degree; Mobitz type II; non-conducted P waves –2nd degree; 2:1 or 3:1 AV node block –3rd degree; complete heart block AV block usually caused by idiopathic fibrosis; other causes include MI, drugs and congenital block
Your consent to our cookies if you continue to use this website.