Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ ECG Findings ++ Regular narrow-complex tachycardia. Flutter waves appear in a rapid sine wave or “sawtooth” pattern, usually in the inferior leads (II, III, aVF). Atrial activity in lead V1 often appears as rapid P waves at a rate approximating 300 bpm. +++ Pearls ++ The AV node’s refractory period usually prevents 1:1 conduction to the ventricles. Usually, conduction is blocked at a ratio of 1:2 to 1:4. The QRS complexes should appear with regular periodicity. However, AV conduction may be variable from beat to beat, creating irregular R-to-R intervals. A conduction ratio of 2:1 is usually difficult to discern, because the two flutter peaks between QRS complexes may look like normal P and T waves. A ventricular rate of 140 to 160 bpm should prompt consideration of the possibility of atrial flutter with 2:1 block. Atrial flutter tends to be more refractory to chemical cardioversion and more susceptible to electrical cardioversion when compared to atrial fibrillation. ++ FIGURE 23.29A Atrial Flutter. (ECG contributor: James V. Ritchie, MD.) Graphic Jump LocationView Full Size||Download Slide (.ppt) ++ FIGURE 23.29B Atrial flutter with 4:1 block. The flutter waves (arrows marking every other flutter wave) may be mistaken for P and T waves. Graphic Jump LocationView Full Size||Download Slide (.ppt) ++ FIGURE 23.29C The “sawtooth” pattern is most apparent in the inferior leads. 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 You already have access! Please proceed to your institution's subscription. Create a free a profile for additional features.