Common Supraventricular and Ventricular Arrhythmias in Children

Abstract

The most common pediatric arrhythmias are tachycardias, and the most common type is supraventricular tachycardia, originating from or above the atrioventricular node and HIS bundle. Ventricular tachycardias are less common but more dangerous. Supraventricular tachycardias usually cause a narrow complex tachycardia unless there is a basal bundle branch block or rate-dependent aberration. A wide QRS tachycardia should be treated as ventricular tachycardias unless proven to be an supraventricular tachycardia with aberration. Diagnosis of both tachyarrhythmia types depends mainly on 12-lead electrocardiography. The most common supraventricular tachycardia type in newborns and infants is atrioventricular reentry tachycardia, related to manifest or concealed accessory pathways and in adolescent atrioventricular nodal reentry tachycardia, whereas focal atrial tachycardias consist of 10%-15% of supraventricular tachycardias during all ages. Supraventricular tachycardias have a low risk of morbidity, and ablation therapy is successful in most types with success rates over 90%. Ventricular tachycardias can be monomorphic or polymorphic, nonsustained or sustained, and can cause more hemodynamic instability than supraventricular tachycardias, requiring more close monitoring and urgent therapies. If hemodynamically unstable, synchronized cardioversion must be performed. Polymorphic ventricular tachycardias are very dangerous and often associated with primary ion channel defects (channelopathies), which can cause sudden cardiac death.

Figure 1.

Normal rhythm variants that can be seen in healthy children. (A) Sinus arrhythmia (“respiratory arrhythmia”) in a 14-year-old boy athlete (normal sinus p waves with regular fixed P-R interval and cyclic and gradually lengthening and shortening of P-P intervals causing the heart rate to increase with inspiration, and decrease with expiration, but always within normal limits) with unchanged morphology are seen. (B) Wandering atrial pacemaker activity seen intermittently during daytime in a 4-year-old female patient (R-R distances are generally equal, as in normal sinus rhythm, with gradually changing p-wave morphology). (C) Ectopic atrial rhythm in a 9-year-old female patient at a rate similar to the sinus rate, mainly occurring at night (originates from a different atrial focus than sinus node, with a rate close to the average sinus rate). (D) Intermittent nodal rhythm seen in a 12- year-old male patient at night (the same narrow QRS as sinus rhythm, without any P waves in front of it).

Figure 2.(

A) Premature atrial contractions (PACs) with aberrant and normal conduction to ventricle shown with red arrows. (B) Electrocardiography at the border of bradycardia (100 bpm) in a newborn with non-conducted bigeminy PACs.

Figure 3.(

A) Sinus tachycardia at a rate of 150/min in a 14-year-old male patient; p waves are the same as sinus p waves. (B) A 12-year-old female patient with narrow QRS tachycardia, where p waves can not be discriminated, and at a rate of 210 bpm.

Figure 4.

Differential diagnosis of narrow QRS-complex tachycardias (6).

Figure 5.(

A) Manifest pre-excitation pattern consisting of short PR interval, delta wave, and wide QRS tirade on 12-channel electrocardiography (ECG); Wolff-Parkinson-White (WPW) pre-excitation. (B) Fast conduction to ventricles of atrial fibrillation in WPW, which can degenerate to ventricular fibrillation. (C) Permanent junctional reciprocal tachycardia (PJRT) recording with long RP interval and negative P waves in the inferior leads (DII-III and aVF) are seen. (D) Very short RP interval in ECG (retrograde p waves seen immediately after the QRS as “pseudo-r” in lead V-1 and a “pseudo-s” in lead D-III) seen in typical AVNRT. (E) Atypical AVNRT ECG with long R-P interval is seen (differential diagnosis includes other long R-P interval SVTs such as focal atrial tachycardia and PJRT). (F) Focal atrial tachycardia ECG; p waves seen on the ground after adenosine administration, returning to the isoelectric line. (G) Atrial flutter ECG with typical saw-tooth-like p waves.

Figure 6.(

A) Premature ventricular contractions (PVCs) uniform in morphology and “bigeminy” in frequency, without any other poor prognostic features in the examination, considered “benign.” (B) Triplet monomorphic PVCs (also called ventricular tachycardia (VT)) at a slow rate. (C) Four to six PVCs in polymorphic “Salvo” form, requring careful evaluation. (D) Multiform (polymorphic) PVCs in 2 different morphologies. They became more frequent and finally evolved into polymorphic VT in the exercise test and are considered “malignant.” (E) An interpolated PVC requires more attention, as the probability of coinciding with the T wave in front of it increases (“R on T” phenomenon). (F) Another PVC with a malignant feature; a very short coupling interval causes the “R on T” phenomenon, initiating polymorphic VT.

Figure 7.(

A) Atrioventricular dissociation in the form of p waves (thick red arrows) that can be distinguished from time to time between the QRS and T waves, and 2 fusion beats (thin black arrows) in the middle and near the end of the ECG, characterized by a narrower QRS than the VT but wider than the normal QRS. (B) Atrioventricular dissociation and a “capture” beat at the sixth beat from the beginning (in normal sinus QRS morphology).

Figure 8.

Differential diagnosis of wide QRS-complex tachycardia (6).

Figure 9.(

A) Idiopathic right ventricle outflow tract ventricular tachycardia (VT) electrocardiography (ECG) shows typical left bundle branch block pattern and inferior axis (positive QRS in leads D-II, D-III, and aVF). (B) In idiopathic LV posterior fascicular VT ECG, typically right bundle branch block pattern and superior axis (negative QRS in leads D-II, D-III, and avF) are seen, and the QRS is relatively narrow. (C) Superior-inferior alternating QRS is seen in “bidirectional” (polymorphic) VT (typically seen in CPVT). (D1) Long QT type-1 ECG sample with broad-based T waves are typical. (D2) Example of a long QT type-2 ECG with typical biphasic and low amplitude T waves. (D3) Example of long QT type-3 with normal-width T wave but prolonged “ST interval.” (E) T wave alternans, which is considered as a high-risk factor in Holter recording (major changes from beat to beat). (F) “Torsades de Pointes” (polymorphic VT), mostly initiated by a premature ventricular contraction that creates an “R on T” phenomenon by overlapping the T wave of the previous QRS due to prolonged QT.