Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ ECG Findings ++ Irregularly irregular narrow-complex tachycardia Absence of P-waves, but fibrillatory atrial activity may be seen +++ Pearls ++ Atrial fibrillation is typically a narrow-complex rhythm, but in presence of underlying bundle branch block, aberrant conduction, or accessory pathway, it may be wide complex. Most “irregularly irregular” rhythms are due to atrial fibrillation, but other rhythms may produce similar findings. These include multifocal atrial tachycardia, atrial flutter with variable AV block, and frequent premature ventricular contractions. Hemodynamically stable patients are treated with chemical rate or rhythm control with a goal heart rate of < 120 bpm. In hemodynamically unstable patients, synchronized cardioversion is the treatment of choice. Risks of cardioversion include subsequent stroke. When a very fast (>200 bpm) irregular tachycardia is seen with changing QRS shape and morphology, suspect atrial fibrillation with Wolff-Parkinson-White syndrome (WPW) and avoid AV nodal blocking agents as this can promote conduction over the accessory pathway and lead to ventricular tachycardias and death. ++ FIGURE 23.28A Atrial Fibrillation. (ECG contributor: R. Jason Thurman, MD.) Graphic Jump LocationView Full Size||Download Slide (.ppt) ++ FIGURE 23.28B R-to-R interval varies in an “irregularly irregular” pattern (double arrows). The baseline “rumble,” representing “F waves,” may be very fine or even indiscernible. Graphic Jump LocationView Full Size||Download Slide (.ppt) ++ FIGURE 23.28C The baseline “rumble” may be very coarse, resembling atrial flutter waves. Graphic Jump LocationView Full Size||Download Slide (.ppt) Your Access profile is currently affiliated with '[InstitutionA]' and is in the process of switching affiliations to '[InstitutionB]'. Please click ‘Continue’ to continue the affiliation switch, otherwise click ‘Cancel’ to cancel signing in. Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Password? Forgot Username? Sign in via OpenAthens Sign in via Shibboleth