Influence of improved antenatal detection on the outcomes of complete atrioventricular block diagnosed in fetal-neonatal life and childhood periods - a single-centre experience in South Wales for 55 years.

OBJECTIVE: This study aimed to analyse the influence of improved antenatal detection on the course, contemporary outcomes, and mortality risk factors of the complete atrioventricular block during fetal-neonatal and childhood periods in South Wales. METHODS: The clinical characteristics and outcomes of complete atrioventricular block in patients without structural heart disease at the University Hospital of Wales from January 1966 to April 2021 were studied. Patients were divided into two groups according to their age at diagnosis: I-fetal-neonatal and II-childhood. Contemporary outcomes during the post-2001 era were compared with historical data preceding fetal service development and hence earlier detection. RESULTS: There were 64 patients: 26 were identified in the fetal-neonatal period and the remaining 38 in the childhood period. Maternal antibodies/systemic lupus erythematosus disease (anti-Ro/Sjögren's-syndrome-related Antigen A and/or anti-La/Sjögren's-syndrome-related Antigen B) were present in 15 (57.7%) of the fetal-neonatal. Fetal/neonatal and early diagnosis increased after 2001 with an incidence of 1:25000 pregnancies. Pacemaker implantation was required in 34 patients, of whom 13 were diagnosed in the fetal-neonatal group. Survival rates in cases identified before 2001 were at 96.3% (26/27), whereas it was 83.8% (31/37) in patients diagnosed after 2001 (P > 0.05). Other mortality risk factors comprised a lower gestational week at birth, maternal antibodies, and an average ventricular heart rate of < 55 bpm. CONCLUSIONS: Fetal diagnosis of complete atrioventricular block is still portends high fetal and neonatal mortality and morbidity despite significantly improved antenatal detection after 2001. Pacemaker intervention is needed earlier in the fetal-neonatal group. Whether routine antenatal medical treatment might alter this outcome calls for further prospective multicentre studies.

Favourable outcome for hydrops or cardiac failure associated with fetal tachyarrhythmia: a 20-year review.

BACKGROUND: Prognosis of fetuses with hydrops and tachyarrhythmia has been portrayed as poor in most published reports. This might lead to biased counselling, unnecessary caesarean section, preterm delivery, and even termination of pregnancy. AIMS: To evaluate contemporary fetal and postnatal outcomes of hydropic fetuses with fetal tachyarrhythmia when it is treated effectively and monitored systematically. METHODS: This is a retrospective review of a single centre experience at the University Hospital of Wales over a 20-year period. All fetuses received high doses of flecainide and digoxin combination treatment. Tachycardia response rate, time to arrhythmia and hydrops resolution, fetal and postnatal morbidity, and mortality rates were analysed. RESULTS: Twenty fetuses were diagnosed with hydrops fetalis and received treatment. The mechanism of fetal tachyarrhythmia was supraventricular tachycardia in thirteen and atrial flutter in eight cases. Among the 20 fetuses treated, the overall tachycardia response rate was 90% (18/20) with the restoration of sinus rhythm in 85% (17/20) of the cases. The median time to restore sinus rhythm or to rate control of the arrhythmia was 1.5 days (range 12 hours to 13 days). Hydrops resolved in 17 of the 20 fetuses, with a median time of 12 days (range 3-21 days). Four fetuses went into spontaneous preterm birth and one fetus was delivered early due to worsening hydrops. No significant neurological morbidity was observed in surviving neonates and infants on clinical examination. There was one postnatal death due to respiratory complications of prematurity in the non-responsive supraventricular tachycardia case. CONCLUSIONS: High-dose flecainide and digoxin combination offers effective treatment strategy in fetuses with hydrops and tachyarrhythmia with favourable outcomes. This study may guide more realistic counselling for pregnancies complicated by tachyarrhythmia and hydrops.

Clinical and genetic characteristics and course of congenital long QT syndrome in children: A nine-year single-center experience.

OBJECTIVE: Long QT syndrome (LQTS) is an inherited primary arrhythmia syndrome associated with life-threatening ventricular arrhythmias and sudden death. This study aimed to report the clinical and genetic characteristics and outcomes of children diagnosed as having LQTS in a tertiary pediatric cardiology center in Turkey. METHODS: This was a retrospective review of pediatric patients diagnosed as having LQTS at our center from January 2011 to April 2020. RESULTS: A total of 145 patients (76 males) were included, with a mean age of 9.2±4.5 years and a mean weight of 35.7±18.5 kg; 38 (26.2%) were identified as having LQTS during family screening, whereas a significant proportion of patients were asymptomatic at presentation, 15 patients (10.3%) were diagnosed after previous cardiac arrest, and 26 patients (18%) had syncope. The mean Schwartz score was 4.5 points (range, 3-7.5 points). Furthermore, 107 patients (82%) were confirmed to have a pathogenic mutation for LQTS genes. All patients received beta-blockers. Implantable cardioverter-defibrillator insertion was performed in 34 patients (23.4%). Left or bilateral cardiac sympathetic denervation was performed in 9 patients (6.2%). Median follow-up time was 35.6±25.8 months. Five (3.4%) patients died during the follow-up. Statistical analyses of risk factors for major cardiac events revealed that the QTc was >500 ms and that T wave alternans, high Schwartz score, and Jervell and Lange-Nielsen syndrome were strong and significant predictors of cardiac events. CONCLUSION: LQTS has a variety of clinical manifestations. Patients' symptoms ranged between asymptomatic and sudden cardiac death (SCD). By raising the awareness of physicians regarding the disease, SCD might be prevented in the early period.

Early postoperative arrhythmias in patients undergoing congenital heart surgery.

BACKGROUND: This study aims to evaluate early postoperative arrhythmias in children undergoing congenital cardiac surgery. METHODS: A total of 670 pediatric patients (355 males, 315 females; median age: 4 months; range, 1 day to 18 years) who underwent cardiac surgery due to congenital heart defects between December 2018 and November 2019 were included. The rate of postoperative arrhythmias, diagnosis, potential risk factors, and management strategies were evaluated. Multivariate regression analysis was used to identify significant factors of development of postoperative arrhythmias. RESULTS: Tachyarrhythmia was detected in 54 patients (8.1%), and the most common tachyarrhythmia was junctional ectopic tachycardia. Medical treatment was required in 25/38 (66%) of junctional ectopic tachycardia patients. Amiodarone was initiated in 18, dexmedetomidine in five, and flecainide + amiodarone in two of the patients. Different degrees of atrioventricular block were observed in 30 patients (4.5%). In 12 patients, permanent pacemakers were implanted during hospitalization. Age at the time of surgery under one-year-old, high inotropic scores, prolonged operation time, and high Aristotele"s scores were independent risk factors associated with early postoperative arrhythmia (p<0.05). The most common operations associated with early postoperative arrhythmia were left ventricular outflow tract, (6/20, 30%), complete atrioventricular septal defect (13/53, 24%), and tetralogy of Fallot (20/134, 14%) surgeries. CONCLUSION: Cardiac arrhythmias are common in the early period after congenital heart surgery in children. The diagnosis and frequency of arrhythmias may vary according to different surgical procedures.

Association of Fetal Atrial Flutter with Neonatal Atrioventricular Re-entry Tachycardia Involving Accessory Pathway: A Link to be Remembered.

To investigate prenatal and postnatal outcomes of atrial flutter and its association with the development of a second tachycardia, following restoration of sinus rhythm, in the fetus or newborn. This study is a retrospective review of all fetuses that presented with atrial flutter from January 2001 to December 2019 at the University Hospital of Wales, Cardiff, UK. The specific type of arrhythmia, its time of appearance and clinical characteristics, echocardiographic findings, medical management, and postnatal outcomes were evaluated. Sixteen fetuses were diagnosed with atrial flutter (AFL). Thirteen fetuses had persistent AFL and three fetuses had intermittent AFL. Seven patients had hydrops, of which one had Ebstein's anomaly and the other six had normal hearts. Three of the fetuses that presented with AFL were diagnosed at 20, 21, and 23 weeks' gestation and the remainder were diagnosed in the third trimester. Thirteen patients with AFL received antiarrhythmic drugs and three were delivered without any treatment. Five fetuses with AFL developed atrioventricular reciprocating tachycardia following DC cardioversion after birth, and four of them exhibited pre-excitation on the ECG. These five patients (31.3%) required postnatal antiarrhythmic treatment for up to 2 years. Pre-excitation disappeared in two patients during follow-up and two asymptomatic patients with neonatal pre-excitation required accessory pathway ablation. Fetal atrial flutter has a strong association with atrioventricular reciprocating tachycardia and ventricular pre-excitation in the neonatal period. Therefore, electrocardiograms should be carefully reviewed in newborns following the initial resolution of atrial flutter.

Clinical characteristics of hypertrophic cardiomyopathy in children: An 8-year single center experience.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is the second most common pediatric cardiomyopathy. Although there is a large body of literature about HCM in adults, there is limited information on HCM in childhood. We evaluated various aspects of pediatric HCM patients treated at our center. METHODS: We identified 152 pediatric patients with HCM between October 2011 and October 2019. Clinical history, invasive (ICD, pacemaker, electrophysiologic study, catheter ablation therapy) and non-invasive (ECG, holter moniterization, echocardiography, cardiac MR, genetic study, medicam treatment) data were collected and evaluated. RESULTS: The mean ± standard deviation age of patients was 8.9 ± 5.7 years (1 month-18 years) and 67.8% were male. The most frequent clinical symptoms were murmur and palpitations. Three cases (2%) had aborted sudden death as the first manifestation of HCM. Of these patients, 120 (78.9%) had non-syndromic HCM and 32 (27.2%) had syndromic HCM. Asymmetric septal hypertrophy was common (48.3%) in the non-syndromic group, whereas concentric hypertrophy was common (56.2%) in syndromic group. Left ventricular outflow tract obstruction (LVOTO) occurred in 39 (25.6%) patients. Nine (5.9%) patients underwent electrophysiologic study and/or ablation and 16 patients underwent surgical intervention. Implantable cardioverter defibrillator (ICD) insertion was performed in 38 patients (26 transvenous, 12 epicardial). ICDs were inserted in three (7.9%) patients for secondary prevention; in the remaining patients (92.1%) the devices were placed for primary prevention. Mean SD follow-up time was 27.1 ± 22 months. Five (3.3%) patients died during the follow-up. No patient had heart transplantation or a long-term assistive device. CONCLUSION: The etiology of HCM is heterogeneous and present at any age. It is important to determine the timing of surgery and potential risks for sudden cardiac arrest. As most cases of HCM are familial, evaluation of family members at risk should be a routine component of clinical management.

Electrophysiologic characteristics and catheter ablation results of tachycardia-induced cardiomyopathy in children with structurally normal heart.

OBJECTIVE: The aim of this study is to present electrophysiologic characteristics and catheter ablation results of tachycardia-induced cardiomyopathy (TIC) in children with structurally normal heart. METHODS: We performed a single-center retrospective review of all pediatric patients with TIC, who underwent an electrophysiology study and ablation procedure in our clinic between November 2013 and January 2019. RESULTS: A total of 26 patients, 24 patients with single tachyarrhythmia substrates and two patients each with two tachyarrhythmia substrates, resulting with a total of 28 tachyarrhythmia substrates, underwent ablation for TIC. The median age was 60 months (2-214 months). Final diagnoses were supraventricular tachycardia (SVT) in 24 patients and ventricular tachycardia (VT) in two patients. The most common SVT mechanisms were focal atrial tachycardia (31%), atrioventricular reentrant tachycardia (27%), and permanent junctional reciprocating tachycardia (15%). Radiofrequency ablation (RFA) was performed in 15 tachyarrhythmia substrates, and cryoablation was performed in 13 tachyarrhythmia substrates, as the initial ablation method. Acute success in ablation was achieved in 24 out of 26 patients (92%). Tachycardia recurrence was observed in two patients (8%) on follow-up, who were treated successfully with repeated RFA later on. Overall success rates were 92% (24 out of 26) in patients and 93% (26 out of 28) in substrates. On echocardiography controls, the median left ventricular recovery time was 3 months (1-24 months), and median reversible remodeling time was 6 months (3-36 months). CONCLUSION: TIC should be kept in mind during differential diagnosis of dilated cardiomyopathy. Pediatric TIC patients can be treated successfully and safely with RFA or cryoablation. With an early diagnosis of TIC and quick restoration of the normal sinus rythm, left ventricular recovery, and remodeling may be facilitated.

Clinical features and arrhythmic complications of patients with pediatric-onset arrhythmogenic right ventricular dysplasia.

OBJECTIVE: Arrhythmogenic right ventricular dysplasia (ARVD) is a myocardial genetic disease that occurs primarily in the right ventricle. Patients with ARVD may present with severe ventricular arrhythmias, syncope, and cardiac arrest. The purpose of this study is to evaluate the clinical features and arrhythmic complications of patients with pediatric-onset ARVD. METHODS: Patients diagnosed with ARVD between January 2010 and January 2019 were included in this study. RESULTS: A total of 19 patients with ARVD were evaluated. Of them, 15 patients were male, and their mean age was 12±4 years. The most common symptoms were palpitations (n=6), syncope (n=4), and heart failure symptoms (n=2). Five patients were asymptomatic. Thirteen patients had an epsilon wave; all patients ≥14 years had a T wave inversion in V1-3. Premature ventricular contractions (PVCs) were observed in 15 patients, and ventricular tachycardia (VT) was observed in 9 patients. All patients underwent cardiac magnetic resonance imaging (MRI). Echocardiography and cardiac MRI of two patients were normal at the time of admission; patients were in the concealed phase, and the diagnosis was made by ECG, Holter monitoring, and genetic findings. We administered a beta-blocker in all patients. Two patients underwent an electrophysiological study and ablation because of PVC/VT. An implantable cardiac defibrillator was implanted in 8 patients. The mean follow-up period was 21.5±11 months. Two patients were deceased with incessant VT and heart failure, and one patient was deceased with multiorgan dysfunction after biventricular assist device implantation (n=3). CONCLUSION: Diagnosis of pediatric-onset ARVD might be much more difficult in children. Sudden cardiac death might be prevented in the early period by raising the awareness of physicians about the disorder. Prevention of sudden death with implantable cardiac defibrillators is crucial in the management of these patients. It should be kept in mind that children with structurally normal hearts may present with an earlier concealed phase and can be diagnosed with ARVD.

Transcatheter occlusion of antegrade pulmonary blood flow in children with univentricular heart.

BACKGROUND: This study aims to evaluate the results of transcatheter occlusion of antegrade pulmonary blood flow in children with univentricular heart. METHODS: Medical data of a total of seven patients (4 females, 3 males; median age 11.7 years; range, 1 to 24 years) who underwent transcatheter occlusion of the antegrade pulmonary blood flow following Glenn shunt or Fontan operation between September 2014 and January 2017 were retrospectively analyzed. Data including demographic and clinical characteristics of the patients, type of surgery, echocardiographic and cardiac catheterization findings were recorded. RESULTS: Four patients had a previous pulmonary artery banding operation, while three had pulmonary stenosis. Two patients had facial and upper extremity edema after Glenn operation, one had prolonged pleural effusion, one had prolonged pleural effusion after Fontan operation, and one developed dyspnea and effort intolerance several years after Fontan operation. In two patients, antegrade pulmonary blood flow was occluded to decrease systemic ventricular load before surgery. The Amplatzer Septal Occluder was used in five patients and the Amplatzer Vascular Plug-2 was used in two patients. Two patients developed transient, complete atrioventricular block during the procedure and the procedure was terminated early in one of these patients. Transient hemolysis was observed in one patient following the operation. CONCLUSION: Transcatheter occlusion of antegrade pulmonary blood flow is an effective alternative to surgery in patients with hemodynamic compromise after Glenn shunt or Fontan operation.

Arrhythmia during diagnostic cardiac catheterization in pediatric patients with congenital heart disease.

OBJECTIVE: Diagnostic and interventional cardiac catheterization procedures for congenital heart diseases (CHD) are becoming increasingly more popular, and arrhythmia is a well-known complication. This study was an evaluation of the incidence and causative agents of arrhythmia and the subsequent treatment strategies applied during cardiac catheterization. METHODS: The catheterization data of all of the patients who underwent diagnostic cardiac catheterization for CHD between January 2012 and 2018 at a single center were examined retrospectively. RESULTS: A total of 1316 children underwent diagnostic cardiac catheterization due to CHD. The median age and body weight was 18 months (6 days-21 years) and 9.9 kg (2.2-135 kg), respectively. Patients with ventricular septal defect (281 patients) and those with tetralogy of Fallot (257 patients) represented 2 major groups of the study population. In 93 (7%) patients, arrhythmia developed during cardiac catheterization. Among them, there were 58 (62%) cases of bradyarrhythmia and 35 (38%) cases of tachyarrhythmia. Arrhythmia was classified as low, high, or major, according to the adverse event severity score; the rates were 2.7%, 4.3%, and 1.2%, respectively. In 36 (39%) patients, there was no need for therapy, whereas 57 (61%) required treatment to eliminate the arrhythmia. Treatment modalities included catheter manipulation in 15, pharmacological therapy in 24, and cardioversion in 3 patients. Eleven patients required cardiopulmonary resuscitation. Temporary pacemaker implantation was required in 2 patients, while 2 others underwent permanent pacemaker implantation secondary to catheterization-related arrhythmia. There were no cases of mortality secondary to catheterization-related arrhythmia. CONCLUSION: Diagnostic cardiac catheterization in CHD may result in various types of cardiac arrhythmias. The proper management of arrhythmias may reduce morbidity and mortality related to cardiac catheterization.

Rhythm disturbances and treatment strategies in children with congenitally corrected transposition of the great arteries.

BACKGROUND: We aimed to evaluate rhythm abnormalities in cases of congenitally corrected transposition of the great arteries (ccTGA) and associated treatment strategies. PATIENTS AND METHODS: This retrospective cohort study included 65 pediatric patients with ccTGA who were admitted to the clinic between 2009 and 2017. The patients were divided into two groups, and surgical data, Holter electrocardiographic (ECG) recordings, ECG recordings, electrophysiological data, and device implantation data on the two groups were compared. RESULTS: Group I (n = 53, 82%) consisted of patients with significant associated lesions, and Group II (n = 12, 18%) consisted of those with minor or no associated lesions (isolated ccTGA). Rhythm abnormalities were diagnosed in 22 (34%) of the patients based on initial ECG findings and Holter ECG recordings. Eleven (17%) of these patients had atrioventricular (AV) block of different degrees, and the other 11 (17%) had supraventricular arrhythmia (SVA). The median follow-up was 49 months (range, 9-89 months), and the rhythm remained normal in 26 (42%) of the patients. Three patients died on follow-up. Of 40 patients with normal initial findings, nine required pacemaker implantation due to complete heart block, and SVA developed in seven patients on follow-up. No ventricular tachycardia was seen initially or on follow-up. Ablation was performed in four patients. During the follow-up period, pacemakers were implanted in 12 (23%) of patients in Group I and 4 (33%) of patients in Group II due to complete heart block. Cardiac resynchronization therapy (CRT) was performed in four patients due to systemic ventricular dysfunction. Notably, all four of these patients had a pacemaker implanted postoperatively.

Sustained tachyarrhythmia in children younger than 1 year of age: Six year single-center experience.

BACKGROUND: The aim of this study was to evaluate the results of non-operational sustained tachyarrhythmia in patients <1 year of age at the present center. METHODS: Between November 2010 and November 2016, the demographic characteristics, type and localization of the tachyarrhythmia, echocardiographic findings, and medical and/or ablation therapy for patients <1 year of age with sustained tachyarrhythmia were evaluated. RESULTS: Of 99 patients, 91 had sustained supraventricular tachycardia, and eight had sustained ventricular tachycardia. The median age was 30 days (range, 1-350 days), and the median weight was 4.2 kg (range, 2-13 kg). The common symptoms were palpitation and restlessness (n = 49, 49.5%), or the tachycardia was detected during routine inspection (n = 25, 25.3%) or fetal echocardiography (n = 11, 11.1%). Nineteen individuals (19%) had left ventricular (LV) dysfunction on first echocardiography. Twenty individuals had congenital heart disease. Common diagnoses were Wolff-Parkinson-White syndrome (n = 27), focal atrial tachycardia (n = 10), permanent junctional reciprocating tachycardia(n = 6), and atrial flutter (n = 6). Seventeen patients underwent medical therapy combined with cardioversion. The most commonly used abortive and acute therapy agents were adenosine, esmolol, and amiodarone. The most common combination therapy was propranolol and amiodarone, followed by a propranolol and propafenone combination. Nine individuals were treated with catheter ablation due to either resistance to medical therapy or LV dysfunction. CONCLUSIONS: Tachyarrhythmias in children <1 year of age are mostly caused by accessory pathways and require multidrug therapy. Catheter ablation is an effective alternative therapy in the case of resistance to medical therapy and/or LV dysfunction.

A case report: Is mexiletine usage effective in the shortening of QTC interval and improving the T-wave alternans in Timothy syndrome?

Timothy syndrome (TS) is a multisystemic disease that occurs because of a mutation in CACN1C gene and is characterized by prolonged QT interval. Mexiletine is a Class 1B antiarrhythmic drug that causes the disappearance of T-wave alternans by shortening QTc and peak-to-end of the T wave. It may block the development of torsades de pointes in a prolonged QT. This study presented the case of a patient diagnosed with TS and had a cardiac arrest history, prolonged QT, and T-wave alternans. After mexiletine treatment, the QTc interval shortened and T-wave alternans disappeared. Such a case has rarely been seen in the literature, and hence considered rare. This case presentation was of particular importance because it highlighted the use of mexiletine besides an initial beta-blocker treatment in the cases with TS.