Current Pediatric Research

- Current Pediatric Research (2009) Volume 13, Issue 1

Supraventricular tachycardia from a left bundle branch block-An unusual presentation of Wolff-Parkinson-White syndrome

Wolff-Parkinson-White syndrome (WPW) is an electrocardiographic diagnosis based on a short PR interval with the presence of a delta wave, but it can mimic a variety of electrocardiographic conditions. We present a 6 year old Saudi female whose WPW was easily mistaken as a left bundle branch block. Wolff-Parkinson-White syndrome, or as frequently abbreviated as WPW, accounts for about 20% of all supraventricular tachycardias (SVTs).[1] With an estimated incidence of 0.3%, it is the commonest of the atrioventricular re-entry tachycardias (AVRTs).[2] In the majority of cases, WPW presents as orthodromic AVRTs (i.e. The conduction of impulses travels through the AV node to the ventricles before being redirected back to the atria through the accessory pathway thus completing a loop, inverse of antidromic AVRT). In about 20% of all cases of WPW, delta waves and PR shortening are not evident on the usual electrocardiogram (EKG), and are referred to as concealed pathways, as they allow SVTs to occur but are not evident outside of those times. Accessory pathways may also present intermittently or in cyclic fashion (concertina) on the EKG i.e. delta waves and short PR intervals may be seen after every few beats and then this cycle is repeated. Classically, WPW are easily recognized because the accessory pathway conducts first and through slowly conducting myocardium before the conducted pulse through the atrioventricular (AV) node and bundle of His overtakes the impulse and depolarizes the rest of the myocardium producing a delta wave prior to the narrow QRS complex. Depending on the size of the accessory pathway and the number of these tracts and their sites, the EKGhas been described as representing right ventricular hypertrophy, posterior myocardial infarction, right bundle branch block (type A), or left ventricular hypertrophy, anterior myocardial infarction, or Left bundle branch block (type B).[3] If the size of the accessory tract depolarizes a large portion of the ventricle at its location, then there will be a short PR interval (<120 ms) followed by a wide QRS complex, and can mimic a bundle branch block. Preexcitation syndromes in children are less common compared to adults,[4] as are EKG patterns that fulfil the criteria of a left bundle branch block. We present a case report of a 5-year-old Saudi girl who suffered from intermittent episodic asthma, recurrent chest tightness, shortness of breath, and palpitations.

Author(s): Abdul Rahim Wong, Nabil AbdurRazak, Saad Mohammad, Al-Hadlaq, Aida Hanum Ghulam Rasool, Abdullah Al-Jarallah

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