Microvolt T-wave alternans during Holter monitoring in children and adolescents

Abstract

Background: Time-domain microvolt T-wave alternans (TWA) has been described as a noninvasive marker of sudden cardiac death in adults. The incidence of TWA in pediatric populations has not been defined well. The aim of the study was to determine peculiarities of TWA in children.

Methods: We examined 68 healthy patients-newborns (20) and children in age group of 7-17 years (48)-and 85 pediatric patients: ventricular premature beats-65; dilated cardiomyopathy (DCMP)-2; long QT syndrome (LQTS)-10; Brugada syndrome (BrS)-5, catecholaminergic ventricular tachycardia (CVT)-3. All underwent Holter monitoring (HM) with definition of the peak value of TWA by modified moving average method.

Results: In healthy newborns, TWA was 32 +/- 8 (12-55) microV (HR 123-156 bmp). In healthy children (7-17 years) it was 30 +/- 11 (10-l 55) microV, (HR 64-132 bmp) without any differences between boys and girls. In all group of patients, TWA were significantly higher (P < 0.05) than in healthy. Circadian peak of TWA was found (90%) in a second part of day and at sleep (8%). Among them 60% (LQTS, BrS, and DCPM) had TWA > 55 microV.

Conclusion: Time-domain TWA during HM in children was independent of age, gender, and heart rate. In 94% healthy children, values of TWA do not exceed 55 microV but 20-50% children with cardiac pathology had TWA more than 55 microV. Night circadian type of TWA in diseases with risk of life-threatening arrhythmias associated with TWA was more than 55 microV.

Figure 1

Relationship between the peak value of TWA and the longest QT interval during Holter monitoring in 48 healthy children in 7–17 years of age. Correlation 0.46, P < 0.05.

Figure 2

(A) Circadian rhythm of the peak value of time domain TWA in 48 healthy children in 7–17 years of age (circadian peak of TWA at 6 PM). (B) Circadian rhythm of the peak value of TWA in 85 children with cardiovascular diseases (circadian peak of TWA at 2–4 PM).

Figure 3

Night circadian peak of TWA in Brugada syndrome (17‐year‐old patient). (A) ECG pattern of Brugada syndrome; (B) maximal peak value of TWA 86 μV at 5:28 AM in modified lead V₁.

Figure 4

The types of pattern location of point of maximal voltage of TWA on JT segment in children in modified lead V₅. (A) segment ST + ascending part of T wave (92%); (B) the peak of the T wave (4%); (C) segment ST (3%); (D) descending part of T wave (1%).