Misinterpretation of sleep-induced second-degree atrioventricular block

Figure 1 Mobitz type II atrioventricular block and vagally-induced type I atrioventricular block[14]. A: Mobitz type II atrioventricular block (AVB). There is regular sinus rhythm with a single non-conducted P wave. The PR intervals before and after the block are constant. The sinus rate is constant. The RR interval encompassing the blocked P wave is twice the RR interval prior to the blocked P wave; B: Vagally-induced type I AVB. There is sinus slowing shown by the long PP interval. The PR intervals before and after a single blocked P wave are constant simulating Mobitz type II block. However, type II AVB is ruled out because of sinus slowing consistent with vagally induced AVB. Citation: Barold DC, Barold SS. ECG Simplified. Facts You will Never Forget. San Marcos: Conductivity Press, 2022. Copyright ©The Author(s) 2019. Published by Conductivity Press.