Ecg contest Response to ECG, August 2020

The PR intervals shorten from beat to beat, until they are superimposed on the QRS complex. Negative T waves are normal until V₄ in children and the QTc interval is normal. Another blocked P wave can be seen in the T wave, thus ruling out isorhythmic atrioventricular dissociation (responses 1, 2, and 4 incorrect). An atrial frequency of 100 bpm is observed along with nodal escape rhythm or infra-Hisian rhythm of 48 bpm (response 3, correct). The rhythm strip confirms diagnosis of complete atrioventricular block (figure 1). Cardiac malformation and maternal anti-Ro/SSA and anti-La/SSB antibodies should be ruled out.¹ Studies (echocardiography, exercise testing, Holter study) are recommended to stratify the risk of sudden cardiac death and inform the need for permanent pacemaker placement.²

Figure 1