TY - CHAP M1 - Book, Section TI - Common Atrial Flutter, Macroreentrant, and Multifocal Atrial Tachycardias A1 - Michaud, Gregory F. A1 - Stevenson, William G. A2 - Jameson, J. Larry A2 - Fauci, Anthony S. A2 - Kasper, Dennis L. A2 - Hauser, Stephen L. A2 - Longo, Dan L. A2 - Loscalzo, Joseph PY - 2018 T2 - Harrison's Principles of Internal Medicine, 20e AB - Macroreentrant atrial tachycardia is due to a large reentry circuit, often associated with areas of scar in the atria. Common or typical right atrial flutter is due to a circuit that revolves around the tricuspid valve annulus, bounded anteriorly by the annulus and posteriorly by functional conduction block in the crista terminalis. The wavefront passes between the inferior vena cava and the tricuspid valve annulus, known as the sub-Eustachian or cavotricuspid isthmus, where it is susceptible to interruption by catheter ablation. Thus, common atrial flutter is also known as cavotricuspid isthmus-dependent atrial flutter. This circuit most commonly revolves in a counterclockwise direction (as viewed looking toward the tricuspid annulus from the ventricular apex), which produces the characteristic negative sawtooth flutter waves in leads II, III, and aVF and positive P waves in lead V1(Fig. 245-1). When the direction is reversed, clockwise rotation produces the opposite P-wave vector in those leads. The atrial rate is typically 240–300 beats/min but may be slower in the presence of atrial disease or antiarrhythmic drugs. It often conducts to the ventricles with 2:1 AV block, creating a regular tachycardia at 150 beats/min, with p waves that may be difficult to discern. Maneuvers that increase AV nodal block will typically expose flutter waves, allowing diagnosis. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accesspharmacy.mhmedical.com/content.aspx?aid=1155973579 ER -