CASE REPORT article
Front. Pediatr.
Sec. Pediatric Cardiology
Pseudo-Wide QRS Complex Tachycardia in an Infant with Complex Congenital Heart Disease
Provisionally accepted
- Maternal and Child Health Hospital of Hubei Province, Wuhan, China
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The initial electrocardiogram (ECG) of a 5-month-old infant with complex congenital heart disease (pulmonary valvular stenosis, ventricular septal defects, and patent ductus arteriosus) revealed a regular wide-QRS tachycardia (169 bpm), initially suggestive of ventricular tachycardia (VT) or supraventricular tachycardia (SVT) with aberrant conduction. However, a subsequent ECG, obtained during spontaneous heart rate deceleration to 143 bpm, showed narrow QRS complexes with discernible sinus P waves and a markedly prolonged PR interval (300ms), establishing the diagnosis of sinus rhythm with biatrial enlargement and first-degree atrioventricular (AV) block. Comparative analysis of these ECGs revealed that the initial tracing did not represent a wide-QRS complex but rather a "pseudo-wide QRS complex" tachycardia. This phenomenon occurs when profound PR prolongation poses concealed sinus P waves overlapping the terminal portion of the preceding QRS complex, mimicking a wide QRS complex. The significant PR interval prolongation, reflecting first-degree AV block, is attributable to underlying anatomical abnormalities causing atrial enlargement and consequent impairment of AV nodal conduction. This case highlights the critical importance of meticulously identifying concealed sinus P waves within wide-QRS rhythms to prevent misdiagnosis and inappropriate interventions.
Keywords: congenital heart disease, Prolonged PR interval, Pseudo-wide QRS tachycardia, R-P fusion, Sinus tachycardia
Received: 09 Jun 2025; Accepted: 18 Dec 2025.
Copyright: © 2025 Li, Jing, Yu, You, Wen and Li. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Heng Li
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