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. 2023 Dec 7;18(12):e0295431.
doi: 10.1371/journal.pone.0295431. eCollection 2023.

Cardiac response to water activities in children with Long QT syndrome type 1

Anna Lundström  1 , Urban Wiklund  2 , Annika Winbo  1   3 , Håkan Eliasson  4 , Marcus Karlsson  2 , Annika Rydberg  1
Affiliations

Cardiac response to water activities in children with Long QT syndrome type 1

Anna Lundström et al. PLoS One. .

Abstract

Background: Swimming is a genotype-specific trigger in long QT syndrome type 1 (LQT1).

Objective: To examine the autonomic response to water activities in children and adolescents with LQT1.

Methods: In this cross-sectional study, LQT1 patients were age and sex matched to one healthy control subject. Electrocardiograms (ECGs) were recorded during face immersion (FI), swimming, diving, and whole-body submersion (WBS). Heart rate (HR) and heart rate variability (HRV) was measured. The high frequency (HF) component of HRV was interpreted to reflect parasympathetic activity, while the low frequency (LF) component was interpreted as reflecting the combined influence of sympathetic and parasympathetic activity on autonomic nervous modulation of the heart.

Results: Fifteen LQT1 patients (aged 7-19 years, all on beta-blocker therapy) and fifteen age and sex matched non-medicated controls were included. No significant ventricular arrhythmias were observed in the LQT1 population during the water activities. Out of these 15 matched pairs, 12 pairs managed to complete FI and WBS for more than 10 seconds and were subsequently included in HR and HRV analyses. In response to FI, the LQT1 group experienced a drop in HR of 48 bpm, compared to 67 bpm in the control group (p = 0.006). In response to WBS, HR decreased by 48 bpm in the LQT1 group and 70 bpm in the control group (p = 0.007). A significantly lower PTOT (p < 0.001) and HF (p = 0.011) component was observed before, during and after FI in LQT1 patients compared with the controls. Before, during and after WBS, a significantly lower total power (p < 0.001), LF (p = 0.002) and HF (p = 0.006) component was observed in the LQT1 patients.

Conclusion: A significantly lower HR decrease in response to water activities was observed in LQT1 subjects on beta-blocker therapy, compared to matched non-medicated controls. The data suggests an impaired parasympathetic response in LQT1 children and adolescents. An aberrant autonomic nervous system (ANS) response may cause an autonomic imbalance in this patient group.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Flow chart of participant inclusion.
LQT1 = long QT syndrome type 1, N = number, FI = face immersion, WBS = whole-body submersion.
Fig 2
Fig 2. Heart rate changes during face immersion and whole-body submersion.
Data is presented as means and standard error of the mean (SEM). N = 12 for both LQTS patients and controls. LQTS = long QT syndrome.
Fig 3
Fig 3. Maximal and minimal heart rate during each event compared to the heart rate at the start of each event (baseline).
Data is presented as mean and SEM. Decrease = difference between Max and Min HR. LQTS = long QT syndrome, HR = heart rate.
See this image and copyright information in PMC

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