Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content +++ ECG Findings ++ Narrow complex, regular tachycardia, rate usually > 140 bpm. Absent, retrograde, or unusual P waves. P waves may be buried in the QRS complex. +++ Pearls ++ SVT occurs when the SA node rhythm is superseded by a faster rhythm, usually originating in the AV node. Three common types are: Atrial tachycardia—originates from an ectopic focus in the atrium. P waves may have an unusual morphology or may be hidden by the preceding T wave. AV nodal reentrant tachycardia (AVNRT) occurs when an electrical impulse reenters the AV node in a circular pattern causing rapid depolarizations of the ventricles. Since the AV node is the origin of the atrial depolarization, the P-wave deflection should be inverted if seen (eg, downgoing in II, III, aVF). AV reentrant tachycardia (AVRT) as seen with bypass tracts outside of the AV node (WPW). Instead of intranodal reentrant activity as seen with AVNRT, an accessory tract provides the reentrant pathway to propagate the tachycardia. ++ FIGURE 23.31A Supraventricular Tachycardia (AVNRT). (ECG contributor: R. Jason Thurman, MD.) Graphic Jump LocationView Full Size||Download Slide (.ppt) ++ FIGURE 23.31B A narrow-complex tachycardia, with no clear P waves preceding the QRS. R-R intervals are regular (double arrows), differentiating this from fine atrial fibrillation. This rhythm converted to a normal sinus rhythm after the administration of intravenous adenosine. 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