Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content +++ ECG Findings ++ PR interval greater than 200 ms (normal 120-200 ms) with no significant variation in PR intervals between beats. Each P wave is followed by a QRS complex. +++ Pearls ++ This type of heart block usually does not affect heart function and can be considered nonpathologic (especially in athletes or patients with higher vagal tone). First-degree block may also occur due to heart disease (myocarditis, rheumatic fever), drugs (digoxin, amiodarone, β-blockers, calcium channel blockers), or as a normal part of aging. ++ FIGURE 23.14A First-Degree AV Block. (ECG contributor: James V. Ritchie, MD.) Graphic Jump LocationView Full Size|Favorite Figure|Download Slide (.ppt) ++ FIGURE 23.14B The PR interval is fixed (double arrows) and is longer than 0.2 seconds, or five small blocks. Graphic Jump LocationView Full Size|Favorite Figure|Download Slide (.ppt) GET ACCESS TO THIS RESOURCE 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 Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. Access My Subscription GET ACCESS TO THIS RESOURCE Subscription Options Pay Per View Timed Access to all of AccessMedicine 24 Hour $34.95 (USD) Buy Now 48 Hour $54.95 (USD) Buy Now Best Value AccessMedicine Full Site: One-Year Individual Subscription $995 USD Buy Now View All Subscription Options