Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content +++ ECG Findings ++ High-voltage QRS suggesting LVH Deep, narrow, “dagger-like” Q waves, especially in the lateral (V5, V6, I, aVL) and inferior (I, III ,aVF) leads Deep S waves in anterior precordial leads Lateral T-wave inversions +++ Pearls ++ Hypertrophic obstructive cardiomyopathy (HOCM) causes hypertrophy of the interventricular septum, causing outflow obstruction, and predisposes the patient to ventricular arrhythmias. Always consider this condition in young athletes with syncope or severe dyspnea on exertion. The Q waves seen in HOCM can be mistaken for Q waves seen in myocardial ischemia; however, infarction Q waves are typically > 40 ms, whereas HOCM Q waves are < 40 ms. ++ FIGURE 23.42A Hypertrophic Cardiomyopathy with Underlying Atrial Flutter with 2:1 Block. (ECG contributor: James V. Ritchie, MD.) Graphic Jump LocationView Full Size||Download Slide (.ppt) ++ FIGURE 23.42B Deep S-wave voltage (28 mm S in V2, large arrow) and narrow Q waves in V5 and V6 (arrowheads). This patient also has atrial flutter with 2:1 block. The additional P waves appear in the ST segments (small arrows). Graphic Jump LocationView Full Size||Download Slide (.ppt) Your MyAccess 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 Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth