Atlas of Pediatric and Youth ECG by Gabriele Bronzetti

Author:Gabriele Bronzetti
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Fig. 11.2 Diagnostic algorithm for tachycardia. Modified with permission from [1]

11.1 ECG Diagnosis

The 12-lead ECG is crucial and normally helps in identifying the type of SVT. Things to be checked are heart rate, P waves (morphology, axis, the relationship between P waves and the QRS complex, PR and RP intervals), QRS complex, starting and finishing pattern of tachycardia, and the response to vagal maneuvers and to drugs (Figs. 11.2 and 11.3) [1]. If the baseline ECG with normal sinus rhythm presents a ventricular pre-excitation (short PR interval, delta wave, wide QRS, ST-T changes), the diagnosis of an atrioventricular reentry tachycardia is obvious, while the presence of a long PR interval should suggest a nodal reentry (dual AV nodal pathways and baseline conduction along the slow pathway), and in the case of Mahaim fibers, a normal PR interval, a pseudo-pre-excitation, and a pattern rS in DIII may be present [4].

When a newborn baby arrives in the emergency room in poor clinical conditions and the 12-lead ECG shows sinus rhythm with large P waves, keep in mind the possibility of a just ceased SVT or VT with AV dissociation. STVs are normally characterized by a narrow QRS complex; however, a wide QRS complex could be present in SVT conducted with aberrancy, Mahaim tachycardia, or antidromic AVRT or VT (AV dissociation, fusion beats, capture beats, concordance throughout the chest leads) (Figs. 11.4 and 11.5). Mahaim fibers connect the anterior wall of the right atria to the right bundle branch, to the fascicles, or to the right distal ventricle and possess decremental conduction capacity; they lead to antidromic arrhythmia with an LBBB morphology. Mahaim arrhythmia is very rare, and Mahaim fibers are frequently a bystander of other arrhythmic mechanisms [1].

Fig. 11.3SVT synopsis. Modified with permission from [1]

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