Association of WPW syndrome and first-degree atrioventricular block

Excerpt

A 28-year-old woman was referred to our hospital because of frequent attacks of paroxysmal tachycardia over a period of 15 years. Her electrocardiogram (ECG) showed sinus rhythm, a PR interval of 100 ms, QRS duration of 200 ms, rS pattern in lead V₁, and an R pattern with slurring in lead V₅, suggestive of Wolff–Parkinson–White (WPW) syndrome type B (Fig. 1 a). However, the PJ interval was 300 ms, indicating the WPW syndrome may be associated with left bundle branch block (BBB). Subsequently, transesophageal atrial pacing was performed (Fig. 1 b). S₂ kickback was performed at a cycle length of 650 ms. When S₁S₂ was between 600 and 340 ms, the S₂R₂ was permanently 150 ms; when S₁S₂ was 330 ms, S₂R₂ was abruptly prolonged to 480 ms, R₂ immediately reverted to normal (the duration was 80 ms), and atrioventricular reentrant tachycardia (AVRT) was induced simultaneously. The inducibility of AVRT ruled out third-degree atrioventricular block (AVB) in the normal pathway (His Purkinje system); the narrow QRS morphology during AVRT excluded BBB; thus, the prolonged PJ interval was suggestive of first-degree AVB in WPW syndrome. Radiofrequency catheter ablation was performed after the clinical features were described to the patient. Postablation ECG revealed sinus rhythm with a narrow QRS complex and a PR interval of 280 ms (Fig. 1 c). The diagnosis of first-degree AVB in the normal pathway was further confirmed. …