Ventricular Arrhythmias In Children Research Articles

A physiologically-based pharmacokinetic modeling approach for dosing amiodarone in children on ECMO.

Extracorporeal membrane oxygenation (ECMO) is a cardiopulmonary bypass device commonly used to treat cardiac arrest in children. The American Heart Association guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiovascular care recommend using amiodarone as a first-line agent to treat ventricular arrhythmias in children with cardiac arrest. However, there are no dosing recommendations for amiodarone to treat ventricular arrhythmias in pediatric patients on ECMO. Amiodarone has a high propensity for adsorption to the ECMO components due to its physicochemical properties leading to altered pharmacokinetics (PK) in ECMO patients. The change in amiodarone PK due to interaction with ECMO components may result in a difference in optimal dosing in patients on ECMO when compared with non-ECMO patients. To address this clinical knowledge gap, a physiologically-based pharmacokinetic model of amiodarone was developed in adults and scaled to children, followed by the addition of an ECMO compartment. The pediatric model included ontogeny functions of cytochrome P450 (CYP450) enzyme maturation across various age groups. The ECMO compartment was parameterized using the adsorption data of amiodarone obtained from exvivo studies. Model predictions captured observed concentrations of amiodarone in pediatric patients with ECMO well with an average fold error between 0.5 and 2. Model simulations support an amiodarone intravenous (i.v) bolus dose of 22 mg/kg (neonates), 13 mg/kg (infants), 8 mg/kg (children), and 6 mg/kg (adolescents). This PBPK modeling approach can be applied to explore the dosing of other drugs used in children on ECMO.

Evaluation of ventricular arrhythmia in children with Wilson's disease; cardiac electrophysiological balance index (iCEB)

Evaluation of ventricular arrhythmia in children with Wilson's disease; cardiac electrophysiological balance index (iCEB)

Predictors of unsuccessful radiofrequency catheter ablation of idiopathic ventricular arrhythmias in children

Ventricular arrhythmias (VAs) in children are generally idiopathic and have a benign course. Catheter ablation (CA) is increasingly becoming a first-line treatment option in children with idiopathic VAs. Acute ablation success reaches 100% procedures and long-term – 87%. Predictors of outcomes of CA in pediatric patients with idiopathic VAs have not been fully investigated.Aim: To identify predictors of long-term unsuccessful outcomes of CA in pediatric idiopathic VAs.Material and Methods. This retrospective study included 164 children aged 7 to 17 years with idiopathic VAs, who underwent CA from 2011 until 2023 in Almazov National Medical Research Centre. Efficiency was assessed in acute period and 6 months after CA.Results. In this study the acute success was 92% and long-term success was 88,4%. In multivariable models, multifocal VAs (odds ratio: 8,814; 95% CI: 1,943–39,981; p = 0,005), effectiveness of antiarrhythmic therapy (odds ratio: 16,522; 95%CI: 1,959–139,374; p = 0,010) and noninducibility of VAs during procedure (odds ratio: 9,369; 95% CI: 1,400–62,684; 0,021), become predictors of long-term unsuccessful outcomes of CA in pediatric idiopathic VAs.Conclusion. In our study there were identified independent predictors of long-term noneffective CA in children with idiopathic VAs, such as multifocal VAs, effectiveness of antiarrhythmic therapy, and noninducibility of VAs CA. In patients with presence of two or more ventricular foci and the effectivness of antiarrhythmic therapy, prolongate drug therapy may be more preferable.

Синдром недостаточности высвобождения кальция - редкий вариант катехоламинергической полиморфной желудочковой тахикардии

Authors present a difficult-to-diagnose clinical case of cotecholaminergic polymorphic ventricular tachycardia (CPVT), a rare hereditary disease, which is characterized by mutations most often in the RYR2 gene with increased function of the ryanodine receptor, which in its turn is the main protein of calcium channels in the sarcoplasmic reticulum of cardiomyocytes. The mechanism of development of the pathology is based on late post-depolarization, which is a trigger for the occurrence of severe ventricular arrhythmias associated with a high risk of sudden cardiac death. Ventricular arrhythmias in children with CPVT can causally be reproduced using an exercise test at a low heart rate threshold. However, there have been reports of sudden cardiac death in individuals who had the loss-of-function RyR2 mutations and who have nevertheless had negative stress test results. The main clinical manifestation is syncope, the genesis of which may remain unknown for a long time. The described clinical case demonstrates the complexity of diagnosis, for which the routine cardiological examination isn’t enough. Specialists therefore have difficulties in making the correct diagnosis and determining the patient management tactics.

Indications and management of implantable cardioverter-defibrillator therapy in childhood hypertrophic cardiomyopathy.

Sudden cardiac death is the most common mode of death during childhood and adolescence in hypertrophic cardiomyopathy, and identifying those individuals at highest risk is a major aspect of clinical care. The mainstay of preventative therapy is the implantable cardioverter-defibrillator, which has been shown to be effective at terminating malignant ventricular arrhythmias in children with hypertrophic cardiomyopathy but can be associated with substantial morbidity. Accurate identification of those children at highest risk who would benefit most from implantable cardioverter-defibrillator implantation while minimising the risk of complications is, therefore, essential. This position statement, on behalf of the Association for European Paediatric and Congenital Cardiology (AEPC), reviews the currently available data on established and proposed risk factors for sudden cardiac death in childhood-onset hypertrophic cardiomyopathy and current approaches for risk stratification in this population. It also provides guidance on identification of individuals at risk of sudden cardiac death and optimal management of implantable cardioverter-defibrillators in children and adolescents with hypertrophic cardiomyopathy.

Electrocardiographic Findings in Children With Growth Hormone Deficiency.

Introduction It has been shown that cardiac functions begin to deteriorate in growth hormone (GH) deficiency even in childhood. However, little is known about how GH deficiency affects arrhythmogenesis. The aim of this study was to evaluate the parameters of P wave dispersion (Pd), QT dispersion (QTd), corrected QT (QTc) dispersion (QTcd), T wave peak-to-end (Tp-e) interval, Tp-e/QT ratio, and Tp-e/QTc ratio in children with GH deficiency. This study alsoaimed to evaluate the relationship of these parameters with insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 (IGFBP-3). Method In the study, records of children diagnosed with GH deficiency in Adana City Training and Research Hospital Pediatric Endocrine Outpatient Clinic between September 2021 and December 2022 were retrospectively reviewed. The control group consisted of children in the same age group who applied to the Emergency Outpatient Clinic with a complaint of chest pain and no pathological finding was detected. The electrocardiograms (ECGs) of all patients were retrospectively evaluated. Results There were a total of 82 children in the study, 41 of whom were diagnosed with GH deficiency and 41 in the healthy control group. The age and male/female ratio of children with GH deficiency were similar to those in the control group (p>0.05). There were 27 (66%) children with complete GH deficiency and 14 (34%) children with partial GH deficiency. P wave dispersion was similar in both GH-deficient children and control group children. It was also similar in children with complete and partial GH deficiency (p>0.05). QT and QTc dispersions were found to be increased in children with GH deficiency, although not statistically significant, compared to the control group (p>0.05). Tp-e interval, Tp-e/QTmax (longest QT interval), and Tp-e/QTcmax (longest QTc interval) ratios were increased in children with GH deficiency compared to the control group (p=0.001, p=0.003, and p=0.001, respectively). QT and QTc dispersion, Tp-e interval, Tp-e/QTmax, and Tp-e/QTcmax ratios were found to be increased in children with complete GH deficiency compared to children with partial GH deficiency, but the difference was not significant (p>0.05). No correlation was found between these ECG parameters and IGF-1, IGFBP-3, and peak GH levels after stimulation tests (p>0.05). Conclusion We found in our study that the Tp-e interval was longer and Tp-e/QT and Tp-e/QTc ratios were increased in children with GH deficiency. These results suggest that the risk of ventricular arrhythmias in children with GH deficiency may start to increase from childhood. However, further prospective studies are needed to confirm our results.

Electrocardiographic Characteristics and Catheter Ablation of Ventricular Arrhythmias Originating From the Moderator Band in Children.

AimsTo investigate the electrocardiographic (ECG) characteristics and catheter ablation of ventricular arrhythmias (VAs) originating from the moderator band (MB) in children.MethodsA total of six children who had VAs originating from the MB—as confirmed by electrophysiological study—and who underwent catheter ablation between January 2016 and December 2020 were retrospectively reviewed. During the procedure, a three-dimensional electroanatomic mapping system was used to facilitate three-dimensional anatomical reconstruction, mapping and ablation. Patients' clinical characteristics, ECG features and procedural data were collected and analyzed.ResultsThe mean age was 8.4 ± 2.6 years (range: 5.3–11 years) and mean weight was 27.7 ± 11.4 kg (range: 17–47 kg). Four patients presented with frequent premature ventricular contraction (PVC), one patient presented with frequent PVC and non-sustained ventricular tachycardia, and one patient presented with sustained monomorphic ventricular tachycardia. The QRS duration averaged 126.3 ± 4.6 ms. In all patients, the VAs had left bundle branch block QRS with left superior frontal plane axes, rapid downstrokes of the QRS in the precordial leads, and late precordial transitions (>V4). During the same period, 10 cases of VAs originated from the posterior-lateral wall of the tricuspid annulus, with a mean QRS duration of 152.8 ± 6.4 ms. Compared to that, VAs of MB origin have narrower QRS widths, downstroke slopes in the inferior lead, sharper downstroke slopes in the precordial lead, and smaller R-wave amplitudes in the V6 lead. All patients experienced immediate ablation success with activations earlier than QRS by 26.0 ± 3.5 ms, and no procedural complications occurring. Only one case had recurrent PVC during a follow-up period ranging from 6 to 36 months.ConclusionMB VAs in children have distinctive ECG morphology and electrophysiological characteristics. Catheter ablation using a three-dimensional electroanatomic mapping system is safe and effective in these patients.

Magnetic resonance imaging diagnostic potential in “idiopathic” ventricular arrhythmias in children

The study aims to assess the role of magnetic resonance tomography (MRI) in identifying the substrate of “idiopathic” ventricular arrhythmias in pediatric patients.Methods. One hundred and seven children with “idiopathic” ventricular arrhythmias were enrolled. All patients underwent MRI on a high-field Magnetom Trio A Tim (Siemens) tomograph with a magnetic field induction of 3.0 T.Results. According to MRI data, dilated ventricles and/or a decreased ejection fraction were found in 55 (51%) patients. Based on structural abnormalities of the myocardium patients were divided into 2 groups: group 1 “normal”, without abnormalities, (69 (64.5%) children); group 2 - “fibrosis”, fibrotic changes were detected on late gadolinium enhancement (38 (35.5%) patients). Significant differences of indexed MR-indicators in these two groups were not found. However, in the “fibrosis” group, biventricular dysfunction occurred significantly more often than in the “normal” group, respectively (14 (37%) and 9 (13%) (p = 0.006)).Conclusion. MRI is important in assessing structural changes in pediatric patients with ventricular arrhythmias, and the combination of MRI results with clinical and electrophysiological data can significantly affect the change in management and treatment strategy in pediatric patients.

Clinical and functional characteristics of children with ventricular arrhythmias depending on the ectopic focus localization

Aim. To determine the prevalence of ventricular arrhythmias (VA) among children with cardiac arrhythmias and to assess the clinical, functional, and electrophysiological characteristics of VA, depending on the localization of the ectopic focus.Methods. The study included 260 children, 153 (58,8%) boys, the mean age of patients was 13.4±3.1years. Based on clinical and anamnestic data, ECG, Holter monitoring, echocardiography, dosed exercise test, invasive electrophysiological study (EPS), radiofrequency ablation (RFA) a comparative assessment of the clinical and functional features of the most frequently diagnosed localizations of the ectopic focus in children with VA was carried out according to the data of invasive EPS, RFA.Results. According to invasive EPI, the most frequent localization of VA in children is the right ventricle outflow tract (RVOT) - 144 (55%), less often - the Valsalva sinuses - 52 (20%) and the RV free wall - 47 (18%). In most cases (255 children, 98%) there was a focal arrhythmia (trigger activity). The localization of ectopia in the RV free wall is characterized by the predominance of single ventricular premature beats (VPB) or in combination with a paired VPB (78,7%) and polymorphism of ventricular complexes (30%). The peculiarity of ventricular tachycardia in this localization is its stable character (17,0%) and low heart rate in volleys (idioventricular rhythm) (12,8%). When the focus was localized in the RVOT, as well as when it was localized in the RV free wall, single VPB or in combination with paired VPB prevailed (84,7%), but polymorphism of ventricular complexes was less often observed (10,4%). Differences in myocardial contractility at the sinus rhythm in right ventricular arrhythmias were revealed. Thus, the ejection fraction at the localization of the lesion in the RV free wall was significantly lower than in the RVOT (63.4±5.5% and 65.8±5.9%, respectively; p<0.01). Hemodynamic significance is characteristic for RV arrhythmias (21.3% and 16.0% of patients) and was practically not observed at the left-sided localization of the arrhythmogenic focus (3.8%; p<0.01). VA in patients without structural heart disease, regardless of the localization of the arrhythmic focus in children, is asymptomatic and is detected, in most cases, within the framework of clinical examination 206 patients, 79.2%. The prevalence of syncope in children with idiopathic VA is 15.8% (41 patients), and in most cases, they are of vaso-vagal origin. In most children (178, 70%), idiopathic VA is dependent on the level of parasympathetic influences on the heart, disappearing or significantly decreasing during exercise, which is revealed during the stress test confirming the high role of autonomic influences on the regulation of heterotopic rhythm in children with VA.Conclusion. VA is a common arrhythmia in children. Depending on the localization of the arrhythmogenic focus, characteristic features of the structure and density of the heart, as well as differences in the contractile function of the myocardium on the sinus rhythm and on the ectopic complex were revealed.

The Role of Cardiac Magnetic Resonance in Evaluation of Idiopathic Ventricular Arrhythmia in Children.

The aim of the study was to assess the role of cardiovascular magnetic resonance (CMR) in the diagnosis of idiopathic VA in children. This retrospective single-centre study included a total of 80 patients with idiopathic ventricular arrhythmia that underwent routine CMR imaging between 2016 and 2020 at our institution. All patients underwent a 3.0 T scan involving balanced steady-state free precession cine images as well as dark-blood T2W images and assessment of late gadolinium enhancement (LGE). In 26% of patients (n = 21) CMR revealed cardiac abnormalities, in 20% (n = 16) not suspected on prior echocardiography. The main findings included: non-ischemic ventricular scars (n = 8), arrhythmogenic right ventricular cardiomyopathy (n = 6), left ventricular clefts (n = 4) and active myocarditis (n = 3). LGE was present in 57% of patients with abnormal findings. Univariate predictors of abnormal CMR result included abnormalities in echocardiography and severe VA (combination of >10% of 24 h VA burden and/or presence of ventricular tachycardia and/or polymorphic VA). CMR provides valuable clinical information in many cases of idiopathic ventricular arrhythmia in children, mainly due to its advanced tissue characterization capabilities and potential to assess the right ventricle.

P wave dispersion and ventricular repolarization changes in children with familial hypercholesterolemia.

Familial hypercholesterolemia is a genetic disease with plasma total cholesterol especially low-density lipoprotein-cholesterol elevation. In this study, we aimed to examine the changes in the electrocardiographies of children with familial hypercholesterolemia. Electrocardiography of 85 patients with a diagnosis of familial hypercholesterolemia, followed up from the Pediatric Metabolism and Pediatric Cardiology outpatient clinic was examined. Electrocardiography of 83 children from the control group who did not have hypercholesterolemia in a similar gender and age range were examined. Heart rate, P wave, PR interval, P wave dispersion, QRS wave, QT interval, corrected QT (calculated with Bazett formula), Tpeak-end interval, QT dispersion, corrected QT dispersion, JT interval, corrected JT (calculated with Bazett formula) were statistically compared. P wave, PR interval, and P wave dispersion values were significantly higher (p < 0.05) in the children with familial hypercholesterolemia. Corrected QT, QT dispersion, corrected QT dispersion, JT interval, corrected JT, Tpeak-end interval were significantly higher than the control group (p < 0.05) in children with familial hypercholesterolemia. These statistical differences in electrocardiography parameters support the risk of atrial and/or ventricular arrhythmia in children with familial hypercholesterolemia. We found that high total cholesterol and low-density lipoprotein-cholesterol variables are associated with an increased risk of cardiac atrial and/or ventricular arrhythmia. The findings suggest that total cholesterol and low-density lipoprotein-cholesterol variability can be used as a new marker for the risk of cardiac arrhythmia. In this case, decreasing total cholesterol and low-density lipoprotein-cholesterol variability below certain thresholds may decrease the risk of cardiac arrhythmia.

Impact of ventricular arrhythmias on outcomes in children with myocarditis.

Children affected with acute myocarditis may progress rapidly into profound ventricular dysfunction and ventricular arrhythmias. The objective of this study is to assess the impact of ventricular arrhythmias on in-hospital mortality and the use of mechanical circulatory support in patients with myocarditis. Pediatric patients (age 0-18years) admitted with myocarditis were identified from the National Inpatient Sample dataset for the years 2002-2015. A total of 12,489 patients with myocarditis were identified. Of them, 1627 patients were with ventricular arrhythmias and 10,862 patients without ventricular arrhythmias. Mortality was higher in those with ventricular arrhythmias (19.5% vs. 2.8%, OR = 8.47; 95% CI 7.16-10.04; p < 0.001). The median length of stay and the median cost of hospitalization were higher in the ventricular arrhythmias group (9days vs. 4days, p < 0.001 and $121,826 vs. $37,658, p < 0.001, respectively). There was a substantial increase in the utilization of extracorporeal membrane oxygenation (ECMO) in patients with ventricular arrhythmias (25.4% vs. 2.7%, OR = 12.40; 95% CI 10.55-14.57; p < 0.001). The use of ventricular assist devices (VADs) was higher in patients with ventricular arrhythmias (4.5% vs. 1.3%, OR = 3.76; 95% CI 2.82-5.01; p < 0.001). An improvement in discharge survival was observed over the years of study in both VA and non-VA groups; associated with this decline in mortality, there was a rising trend of ECMO utilization.Conclusion: Development of ventricular arrhythmia in children with myocarditis is a strong predictor for mortality and ECMO utilization. What is Known: • The clinical presentation of pediatric myocarditis varies from no symptoms of myocardial dysfunction to a rapidly progressing severe congestive heart failure. • Little is known about the predictors of mortality in children with suspected myocarditis. What is New: • Development of ventricular arrhythmia in children with myocarditis is a strong predictor for mortality and ECMO utilization. • Improvement in discharge survival was observed over the years of study; associated with this decline in mortality, there was a rising trend of ECMO utilization.

The Repolarization Period during the Head-Up Tilt Test in Children with Vasovagal Syncope.

Background: Electrocardiography (ECG) and the head-up tilt test (HUTT) are vital in clinical work-up in children with vasovagal syncope (VVS). Ventricular repolarization parameters (QT) measured during the HUTT can be indicative of electrical instability; however, these parameters are not frequently assessed. This study aimed to investigate if ventricular repolarization parameters measured during the HUTT could be indicative of future ventricular arrhythmias in children with syncope. Methods: The shape and amplitude of the T-wave and parameters of the repolarization period (QT, QTpeak, Tpeak-Tend) were evaluated in a resting ECG performed on the first day of hospitalization and in ECGs performed during three phases of the HUTT. Results: In the after-tilt phase of the HUTT, 19/30 children displayed a change in T-wave morphology. QTc was significantly longer in VVS I compared to that in VVS II patients, but not in the controls (p = 0.092). Conclusions: We need further follow-up studies to establish the clinical importance of abnormal dynamics of the repolarization period in children with VVS and negative HUTT. Therefore, children with abnormal T-wave refraction and prolonged duration of the TpTe should remain under the care of a cardiological outpatient.

P3750Efficiency of electrocardiographic algorithms in management of idiopathic outflow tract ventricular arrhythmias in children

Abstract Introduction Ablation of idiopathic ventricular arrhythmias (IVA) originating in left ventricle outflow tract (LVOT) are more challenging as compared to right ventricle outflow tract (RVOT). In recent years, several ECG algorithms predicting the site of origin (SOO) of arrhythmia for adult population have been published. There is a sparse information on their diagnostic performance in children. Purpose The aim of this study was to validate two algorithms: 1) Novel TZ index, 2) V2S/V3R and their combined application in children for predicting the appropriate SOO of IVA. Methods Two groups of children without structural heart disease, thorax anomalies and normal QRS complexes during sinus rhythm were included in the study: 1) patients with IVA with inferior axis who underwent successful RFCA using the 3D-electroanatomical system, 2) patients with paced or mechanically-induced QRS complexes from LVOT or RVOT during other procedures. ECGs were analyzed in a specially developed software for analyzing the amplitude of the QRS complex waves. Semi-automated measurements of amplitudes of QRS complexes and calculations were carried out for 2 published algorithms: 1) Novel TZ index, 2) V2S/V3R. The results of their separate and combined use were compared with SOO of acute successful RFCA and mapping or spot of pacing. Results 108 PVC morphologies (68 from the RVOT and 40 from LVOT) from 74 pediatric patients (age: 14.0±2.9, 39 female) were included into the study. The algorithm V2S/V3R predicted left-sided SOO with a sensitivity and specificity of 94%. Novel TZ-index showed sensitivity of 89% and specificity of 84%. Combined use of Novel TZ-index+V2S/V3R showed high sensitivity (92%) and very height specificity (97%) of the LVOT SOO prediction Conclusion Both algorithms allowed accurate, simple and precise identification of SOO of RVOT/LVOT IVA in children. The combined use of those algorithms may facilitate additional pharmacologic treatment, omitting RVOT mapping with direct mapping LVOT, performance of the procedure by experienced operator.

P3688Familial recurrent autoimmune myocarditis associated with a truncating nonsense mutation of the desmoplakin gene

Abstract Background Arrhythmogenic cardiomyopathy (AC) is an important cause of ventricular arrhythmias in children and young adults. AC is associated with mutation of desmosomal proteins, however, cardiac disease penetrance is incomplete and the clinical course varies widely without recognizable exogenous or epi/genetic co-factors. Importantly, DSP mutation carriers may also display entirely non-cardiac e.g. dermatological phenotypes. Methods and results In two brothers with recurrent fulminant myocarditis, mutation screening of 218 cardiomyopathy-related genes identified a truncating mutation Arg1458* of desmoplakin (DSP). DSP immunhistology unexpectedly revealed complete loss (“knockout”) of DSP protein in endomyocardial biopsies (EMBs), but none of the histological anomalies of AC. Criteria for histological diagnosis of myocarditis were not either fulfilled, and cardiac MRI revealed no features associated with AC. Screening for infections was negative, there was no substance abuse, medication or vaccination. Possible disease triggers were competitive sport events. Myosin and troponin I autoantibodies were detected at titers up to 1:320. We used allele-specific RT-PCR to distinguish if the patients' allele classified as “normal” was actually defective due to promotor mutation or epigenetic silencing. RT-PCRs were done on EMBs and peripheral blood mononuclear cells (PBMCs). In a cohort of dilated cardiomyopathy (DCM) patients we were able to detect DSP transcripts in both, PBMC and left-ventricular heart tissue. RNA sequencing of human PBMC subpopulations suggested that DSP transcription may be restricted to certain immune cell subtypes. RT-PCRs revealed that both Arg1458* carriers have a functional second DSP allele, indicating that their “DSP knockout” occurs at the protein level and may be due to protein instability and degradation within desmosomes. We screened additional existing cohorts for such variants and identified stopgain variant Gln307Ter in a 37-yrs-old woman with ARVC. This patient's sister died from heart failure at the age of 39. In a 59-yrs-old female LVNC patient, stopgain variant Y1391X was identified. Here, family history was unclear, her brother probably died from coronary artery disease. In a 71-yrs-old female DCM patient with no family history, stopgain variant Tyr1512Ter was identified. Conclusions The described patients with DSP truncations strongly suggest the existence of additional genetic or exogenous modifiers driving pathogenesis either way. DSP defects may cause recurrent myocarditis, and mutation screening is advisable to enable early detection of high-risk patients with similar phenotypes. Our finding of complete myocardial DSP protein loss emphasizes that DNA sequencing may miss critical molecular disturbances. It is indispensable to also analyze transcriptome and protein level in the tissue actually affected in a patient in order to recognize his/her individual pathogenesis.

The impact of 21-hydroxylase deficiency on cardiac repolarization changes in children with 21-hydroxylasedeficient congenital adrenal hyperplasia.

Korkmaz HA, Özdemir R, Küçük M, Karadeniz C, Meşe T, Özkan B. The impact of 21-hydroxylase deficiency on cardiac repolarization changes in children with 21-hydroxylase-deficient congenital adrenal hyperplasia. Turk J Pediatr 2019; 61: 228-235. 21-hydroxylase-deficient congenital adrenal hyperplasia (CAH) is associated with cardiovascular risk factors such as, hypertension, obesity, dyslipidemia, and insulin resistance. It is not known whether 21-hydroxylase-deficient CAH is risk factor for atrial and ventricular arrhythmias. The purpose of this study was to compare the 12-lead electrocardiographic measures in patients of 21-hydroxylase-deficient congenital adrenal hyperplasia with those in healthy control subjects matched for age, sex, height, weight and body mass index (BMI). Twenty-five patients with 21-hydroxylase-deficient CAH and twenty-five heathy control subjects were enrolled into this observational, cross-sectional, controlled study. The evaluation consisted of anthropometric measurements, biochemical parameters, and electrocardiographic (ECG) measures. The standard 12-lead electrocardiography was performed in all patients and P-wave dispersion (PWd), QT interval, QTd, QTcd, Tp-e dispersion, Tp-e/QT and Tp-e/QTc ratios were calculated. There were no significant differences in the groups for age, sex, height, weight and BMI (median age 9.4 (1.5-16.75) years, mean weight 37.6±21.5 vs. 27.9±18.3 kg, mean height 125.4±28.9 vs. 114.7±31 cm, mean BMI 21.4±5.7 vs. 18.9±3.4 kg/m2, respectively). P dispersion and Tp-e dispersion were significantly higher in patients of 21-hydroxylase-deficient CAH compared to the healthy subjects (median P dispersion 50 (25) vs. 40 (40) ms, mean Tp-e dispersion 48±15.5 vs. 35.2±17.5 ms). Our study revealed that 21-hydroxylase deficient CAH is associated with high risk of atrial and ventricular arrhythmias in children.

Heart rate variability in children with myocarditis presenting with ventricular arrhythmias.

We aimed to investigate the heart rate variability in children with myocarditis presenting with ventricular arrhythmias. The study compared the characteristics of heart rate variability (HRV) among 67 children with viral myocarditis (VMC), presenting with (n=35) and without (n=32) ventricular arrhythmias and a control group of 30 healthy children. Compared with the control group, the HRV time-domain indicators of children with VMC were significantly lower (p<0.05); also, the indicators of children with ventricular arrhythmias were significantly lower than those of children without ventricular arrhythmias (p<0.05). Equally, during both the lucid and sleep periods, the time-domain indicators of HRV were significantly lower in patients with VMC and arrhythmias than in either the control group (p<0.05) or the group with VMC but no ventricular arrhythmias (p<0.05). We conclude that the HRV of children with VMC probably decreased because of impaired vagal nerve function, with ventricular arrhythmias developing only when the decrease was most significant. Thus, HRV can be a useful predictive indicator for ventricular arrhythmias in children with VMC.

Natural history of idiopathic ventricular arrhythmias in children

Idiopathic ventricular arrhythmia in children is usually benign. Ventricular ectopy in children usually is an incidental finding. Prevalence varies with age: neonates nearly 20%, school age 10%, teenagers 20-30%. During natural history total or partial disappearance of idiopathic ventricular ectopy, spontaneously or after treatment was described in about 23% children with premature ventricular beats, 28% with pairs and 65% with ventricular tachycardia. Arrhythmia more often resolves in infants than in older children, more often in arrhythmia with right than left bundle branch block morphology. Idiopathic ventricular tachycardia or frequent ventricular ectopic beats may in small percentage of pediatric patients lead to ventricular dysfunction, but risk factors of this arrhythmic cardiomyopathy in children are not established. Catheter ablation is recommended in children with ventricular dysfunction or hemodynamic compromise presumed to be due to ventricular arrhythmia, as primary therapy or in patients with arrhythmia not controlled medically

An algorithm for topical electrocardiographic diagnosis of ventricular arrhythmias in children

To develop a topical diagnostic algorithm, the authors analyzed surface ECG in 243 children, including 139 boys, with ventricular arrhythmia. The children’s age was 5 to 17 years (mean 13.4±3.1 years). The found ECG features were compared with the results of endocardial mapping and radiofrequency ablation. Based on the most informative criteria, the authors developed an algorithm for the ECG diagnosis of ventricular arrhythmias in children, which could locate the arrhythmia focus prior to interventional treatment. The most informative electrocardiographic characteristics for the topical diagnosis of ventricular arrhythmias in children were the morphology of the QRS complex in lead V1 and its duration in lead V2. The morphology of the QRS complex in lead I, its duration in lead II, the amplitude of the R wave in lead III, and the ratio of R/S wave amplitudes in lead V3 were proposed to be used as additional characteristics. The algorithm for the ECG diagnosis of ventricular arrhythmias in children makes it possible to assume the localization of the arrhythmogenic focus with an accuracy of 90% and to carry out a directed endocardial mapping, which reduces the duration of radiofrequency ablation and the radiological burden sustained by the child and the staff.

QT dispersion and ventricular arrhythmias in children with primary mitral valve prolapse

To investigate ventricular arrhythmias in children with primary mitral valve prolapse and to evaluate its relation with QT length, QT dispersion, autonomic function tests and heart rate variability measurements. Fourty two children with mitral valve prolapse and 32 healthy children were enrolled into the study. Twelve-lead electrocardiograms, autonomic function tests, echocardiography and 24-hour rhythm Holter tests were performed. Electrocardiograms were magnified digitally. The QT length was corrected according to heart rate. The patients were grouped according to the number of premature ventricular contractions and presence of complex ventricular arhythmia in the 24-hour rhythm Holter monitor test. Heart rate variability measurements were calculated automatically from the 24-hour rhythm Holter monitor test. Orthostatic hypotension and resting heart rate were used as autonomic function tests. The mean age was 13.9±3.3 years in the patient group and 14.6±3.1 years in the control group (p>0.05). Thirty four of the patients (81%) were female and eight (19%) were male. Twenty five of the control subjects (78%) were female and seven (22%) were male. The QT dispersion and heart rate corrected QT interval were found to be significantly increased in the children with primary mitral valve prolapse when compared with the control group (56±16 ms vs. 43±11 ms, p=0.001; 426±25 ms vs. 407±26 ms, p=0.002, respectively). In 24-hour rhythm Holter monitor tests, ventricular arrhythmias were found in 21 out of 42 patients (50%) and 6 out of 32 control subjects (18.8%) (p=0.006). QT dispersion was found to be significantly increased in patients with premature ventricular contractions ≥ 10/day and/or complex ventricular arrhythmias compared to the control group without ventricular premature beats (p=0.002). There was no significant difference in autonomic function tests and heart rate variability measurements between the patient and control groups. The noted increase in QT dispersion may be a useful indicator for the clinician in the evaluation of impending ventricular arrhythmias in children with primary mitral valve prolapse.