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    Jan Janousek

    Background: To assess the impact of different clinical questions on radiation doses acquired during cardiac computed tomography in children. Methods: A total of 116 children who underwent cardiac CT on a third-generation dual-source CT... more
    Background: To assess the impact of different clinical questions on radiation doses acquired during cardiac computed tomography in children. Methods: A total of 116 children who underwent cardiac CT on a third-generation dual-source CT scanner were included. The clinical questions were divided into three main categories: the extent of scanning in the z-axis, coronary artery assessment and cardiac function assessment. Radiation dose values represented as a dose-length product (DLP) in mGy*cm were recorded from the CT scanner protocols. Results: There were significantly higher doses in cases with cardiac function assessment (median DLP 348 versus 59 mGy*cm, p < 0.01) and in cases with coronary artery assessment (median DLP 133 versus 71 mGy*cm, p < 0.01). Conclusion: The most important factor was the assessment of cardiac function, where the median radiation dose was 4.3× higher in patients with a request for cardiac function assessment. We strongly recommend that clinical reque...
    Introduction Hereditary cardiomyopathy is associated with an increased risk of ventricular arrhythmia and sudden cardiac death (SCD). Genetic stratification substantiates risk assessment and enables the primary prevention of SCD in... more
    Introduction Hereditary cardiomyopathy is associated with an increased risk of ventricular arrhythmia and sudden cardiac death (SCD). Genetic stratification substantiates risk assessment and enables the primary prevention of SCD in relatives at risk. We have analyzed the genetic aetiology of SCD in a representative Czech cohort with post mortem diagnosis of various forms of cardiomyopathy and compared it to living cases with these cardiac disorders. Patients and methods Between 2018 and 2019, altogether 47 victims of SCD with post mortem diagnosis of hypertrophic- (HCM; 18/47), arrhythmogenic- (ACM; 19/47) and dilated cardiomyopathy (DCM; 10/47) were identified. Concurrently, genetic testing was performed in 114 living patients (HCM 54/114, ACM 22/114, DCM 38/114). Genetic counselling and cardiologic examination had been carried out in first-degree relatives in all patients/SCD victims. Massively parallel sequencing (MiSeq platform; Illumina.com) was utilized for a custom-made panel...
    Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Supported by Ministry of Health of the Czech Republic Introduction Post mortem genetic analysis in sudden cardiac death... more
    Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Supported by Ministry of Health of the Czech Republic Introduction Post mortem genetic analysis in sudden cardiac death (SCD) represents an important diagnostic tool for the primary prevention of cardiac arrest in victim´s relatives.  Purpose To assess the underlying molecular pathogenesis of SCD in a representative Czech cohort and to evaluate the effects of primary prevention of SCD in genetic relatives.  Patients and Methods Between 2016 and 2020 we have ascertained 100 SCD cases (29 females/71 males; age range 0-52 years). According to autopsy protocols, cases with SCD were divided into categories of sudden arrhythmic death (SADS), sudden unexplained death (in infants; SUD/SUDI), thoracic aortic aneurysm/dissection and cardiomyopathy hypertrophic, arrhythmic, dilated (HCM, ACM, DCM) and sudden infant death syndrome (SIDS). DNA was isolated from post mortem biopsies /...
    This article is to commemorate and celebrate achievements of Professor Milan Šamánek who passed away on 29 April, 2020. Milan was an excellent and visionary paediatric cardiologist who helped to establish paediatric cardiology as a... more
    This article is to commemorate and celebrate achievements of Professor Milan Šamánek who passed away on 29 April, 2020. Milan was an excellent and visionary paediatric cardiologist who helped to establish paediatric cardiology as a speciality in Czechoslovakia and several other east European countries in the late 1970s. Milan was also paramount for connecting the East and West, helping in no small way to establish the Association for European Paediatric Cardiology (AEPC) as the leading learned society in Europe.
    Background— We evaluated the effects of the site of ventricular pacing on left ventricular (LV) synchrony and function in children requiring permanent pacing. Methods and Results— One hundred seventy-eight children (aged <18 years)... more
    Background— We evaluated the effects of the site of ventricular pacing on left ventricular (LV) synchrony and function in children requiring permanent pacing. Methods and Results— One hundred seventy-eight children (aged <18 years) from 21 centers with atrioventricular block and a structurally normal heart undergoing permanent pacing were studied cross-sectionally. Median age at evaluation was 11.2 (interquartile range, 6.3–15.0) years. Median pacing duration was 5.4 (interquartile range, 3.1–8.8) years. Pacing sites were the free wall of the right ventricular (RV) outflow tract (n=8), lateral RV (n=44), RV apex (n=61), RV septum (n=29), LV apex (n=12), LV midlateral wall (n=17), and LV base (n=7). LV synchrony, pump function, and contraction efficiency were significantly affected by pacing site and were superior in children paced at the LV apex/LV midlateral wall. LV dyssynchrony correlated inversely with LV ejection fraction ( R =0.80, P =0.031). Pacing from the RV outflow trac...
    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... more
    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 pop...
    Background— Electromechanical discoordination may contribute to long-term pulmonary right ventricular (RV) dysfunction in patients after surgery for congenital heart disease. We sought to evaluate changes in RV function after temporary RV... more
    Background— Electromechanical discoordination may contribute to long-term pulmonary right ventricular (RV) dysfunction in patients after surgery for congenital heart disease. We sought to evaluate changes in RV function after temporary RV cardiac resynchronization therapy. Methods and Results— Twenty-five patients aged median 12.0 years after repair of tetralogy of Fallot and similar lesions were studied echocardiographically (n=23) and by cardiac catheterization (n=5) after primary repair (n=4) or after surgical RV revalvulation for significant pulmonary regurgitation (n=21). Temporary RV cardiac resynchronization therapy was applied in the presence of complete right bundle branch block by atrial-synchronized RV free wall pacing in complete fusion with spontaneous ventricular depolarization using temporary electrodes. The q-RV interval at the RV free wall pacing site (mean 77.2% of baseline QRS duration) confirmed pacing from a late activated RV area. RV cardiac resynchronization t...
    The extracardiac conduit Fontan (ECF) operation is designed to improve postoperative outcome. Between 8/1998 and 8/2007 77 patients underwent an ECF. Eight patients underwent a Fontan to TCPC conversion. Median age at the time of ECF was... more
    The extracardiac conduit Fontan (ECF) operation is designed to improve postoperative outcome. Between 8/1998 and 8/2007 77 patients underwent an ECF. Eight patients underwent a Fontan to TCPC conversion. Median age at the time of ECF was 6 years (range 2 to 38). Preoperative median pulmonary artery pressure was 13mm Hg (range 4 to 18) and pulmonary vascular resistance was 2,8 (range 0,4 to 4,7). None of patients underwent a fenestration. Twenty two patients (28%) underwent a concomitant intracardiac procedure out of them 19 (24,6%) required cardioplegic arrest. Median cardiopulmonary bypass time was 111 minutes (range 60 to 236). On postoperative day one (POD1) the Fontan pressure was 14,2±3mm Hg (mean+-SD) and the transpulmonary gradient was 8,5±2,4. The POD1 Fontan pressure was found to be significantly higher in patients who had an intracardiac procedure performed. Median chest tube drainage was 14,5 days (range 5 to 210). Median ICU stay was 5 days (range 3 to 47) and hospital stay was 16 days (range 7 to 69). There was one early deaths (1,2%). Of 65 patients reviewed, only 5 patients (7,6%) had new persistent early postoperative arrhythmia or conduction block. Fontan failure occurred in one patient requiring take down of the ECF. In conclusion the ECF operation without a fenestration even in higher risk group of Fontan patients is associated with improved early postoperative outcome. Major factors influencing this outcome are shorter bypass times, avoidance of cardioplegic arrest and individual perioperative management.
    Disturbance of normal AV synchrony and dyssynchronous ventricular contraction may be deleterious in patients with otherwise compromised hemodynamics. This study evaluated the effect of hemodynamically optimized temporary dual chamber... more
    Disturbance of normal AV synchrony and dyssynchronous ventricular contraction may be deleterious in patients with otherwise compromised hemodynamics. This study evaluated the effect of hemodynamically optimized temporary dual chamber pacing in patients after surgery for congenital heart disease. Pacing was performed in 23 children aged 5 days to 7.7 years (median 7.3 months) with various postoperative dysrhythmias, low cardiac output, and/or high inotropic support and optimized to achieve the highest systolic and mean arterial pressures. The following four pacing modes were used: (1) AV synchronous or AV sequential pacing with individually optimized AV delay in 11 patients with first- to third-degree AV block; (2) AV sequential pacing using transesophageal atrial pacing in combination with a temporary DDD pacemaker for atrial tracking and ventricular pacing in three patients with third-degree AV block and junctional ectopic tachycardia, respectively, who had poor signal and exit block on atrial epicardial pacing wires; (3) R wave synchronized atrial pacing in eight patients with junctional ectopic tachycardia and impaired antegrade AV conduction precluding the use of atrial overdrive pacing; (4) Atrio-biventricular sequential pacing in two patients. Pressures measured during optimized pacing were compared to baseline values at underlying rhythm (13 patients with first-degree AV block or junctional ectopic tachycardia) or during pacing modes commonly used in the given clinical situation: AAI pacing (1 patient with slow junctional rhythm and first-degree AV block during atrial pacing), VVI pacing (2 patients with third-degree AV block and exit block and poor sensing on epicardial atrial pacing wires) and dual-chamber pacing with AV delays set to 100 ms (atrial tracking) or 150 ms (AV sequential pacing) in 7 patients with second- to third-degree AV block and functional atrial pacing wires. Optimized pacing led to a significant increase in arterial systolic (mean) pressure from 71.5 +/- 12.5 (52.3 +/- 9.0) to 80.5 +/- 12.2 (59.7 +/- 9.1) mmHg (P < 0.001 for both) and a decrease in central venous (left atrial) pressure from 12.3 +/- 3.4 (10.5 +/- 3.2) to 11.0 +/- 3.0 (9.2 +/- 2.7) mmHg (P < 0.001 and < 0.005, respectively). In conclusion, several techniques of individually optimized temporary dual chamber pacing leading to optimal AV synchrony and/or synchronous ventricular contraction were successfully used to improve hemodynamics in patients with heart failure and selected dysrhythmias after congenital heart surgery.
    Background/Aims: Since β-adrenoceptors have been shown to affect cardiac gap junction channels, we wanted to elucidate the possible effect of metoprolol on the gap junction protein connexin-43, using racemic RS-metoprolol or the isomer... more
    Background/Aims: Since β-adrenoceptors have been shown to affect cardiac gap junction channels, we wanted to elucidate the possible effect of metoprolol on the gap junction protein connexin-43, using racemic RS-metoprolol or the isomer R-metoprolol (no β-adrenoceptor blockade) or S-metoprolol (β1-adrenoceptor blocker). Methods: Cultured neonatal rat cardiomyocytes were exposed to either RS-metoprolol or R-metoprolol or S-metoprolol (0.1 µmol/l each) without or with additional isoprenaline (0.1 µmol/l) treatment for 24 h. Results: The β-blocker treatment did not alter the frequency of spontaneously beating cardiomyocytes, whereas sole isoprenaline administration significantly enhanced the beating frequency by about 40%. This rise could be blocked by concomitant treatment with S- or RS-metoprolol but not with R-metoprolol. Connexin-43 protein was significantly enhanced by isoprenaline and by R-, S- or RS-metoprolol treatment alone as well as with the combined administration of isopren...
    In a 7-year-old boy with normal hearing suffering from repeated syncope an extremely prolonged QTc interval (up to 700 ms) was found. The mother was completely asymptomatic and the father had an intermittently borderline QTc interval... more
    In a 7-year-old boy with normal hearing suffering from repeated syncope an extremely prolonged QTc interval (up to 700 ms) was found. The mother was completely asymptomatic and the father had an intermittently borderline QTc interval (maximum 470 ms) but no symptoms. In the proband a mutation analysis of KCNQ1 gene revealed a homozygous 1893insC mutation. The parents were heterozygous for this mutation. There was no consanguineous marriage in the family. The clinical relevance of these findings is that apparently normal individuals may have a latent reduction of repolarizing currents, a "reduced repolarization reserve," because they are carriers of latent ion channel genes mutations.
    Class IC antiarrhythmic drugs have recently been shown to be effective in some patients with atrial ectopic tachycardia. We therefore studied the efficacy of these drugs in patients with congenital junctional ectopic tachycardia.... more
    Class IC antiarrhythmic drugs have recently been shown to be effective in some patients with atrial ectopic tachycardia. We therefore studied the efficacy of these drugs in patients with congenital junctional ectopic tachycardia. Follow-up data on patients with junctional ectopic tachycardia suggest that this potentially lethal arrhythmia may cease spontaneously in a significant proportion of affected children. Therefore, temporary antiarrhythmic treatment appears to be the therapy of choice. The efficacy of propafenone was prospectively assessed in four infants with junctional ectopic tachycardia (ventricular rate 180, 185, 210 and 320 beats/min, respectively). The diagnosis of junctional ectopic tachycardia was established before the age of 2 months in all four infants. Propafenone was given orally in a mean dose of 350 (300 to 500) mg/m2 body surface area per day. Success of therapy was determined by serial electrocardiograms (ECGs) and Holter ambulatory ECG monitoring. In two patients, junctional ectopic tachycardia was completely suppressed. In the remaining two patients, the tachycardia rate decreased to less than 150 beats/min. Serum propafenone levels did not correlate with efficacy of treatment. The mean duration of therapy was 18 months (range 3 to 36). No chemical or clinical side effects were noted. Because of its effectiveness, safety and lack of side effects, propafenone appears to be a valuable drug in the treatment of junctional ectopic tachycardia in newborns and infants.
    The etiology of dilated cardiomyopathy associated with congenital complete AV block has not yet been clarified. Two infants with AV block of autoimmune and surgical etiology, respectively, had received a dual-chamber right... more
    The etiology of dilated cardiomyopathy associated with congenital complete AV block has not yet been clarified. Two infants with AV block of autoimmune and surgical etiology, respectively, had received a dual-chamber right ventricular-based pacemaker and developed dilated cardiomyopathy with severe septal to left ventricular free-wall dyssynchrony 3.4 (0.9) years later. After 4 weeks of biventricular pacing and spontaneous junctional narrow QRS rhythm, respectively, both children showed significant improvement in left ventricular function along with reverse remodeling. Thus, electromechanical dyssynchrony associated with conventional right-ventricular-based DDD pacing may play a significant role in the development of dilated cardiomyopathy in the young.
    Thirteen patients with d-transposition of the great arteries after the Mustard/Senning procedure underwent electrophysiological study for recurrent intraatrial reentrant tachycardia (IARTs). In 8 patients, a 20-pole electrode catheter and... more
    Thirteen patients with d-transposition of the great arteries after the Mustard/Senning procedure underwent electrophysiological study for recurrent intraatrial reentrant tachycardia (IARTs). In 8 patients, a 20-pole electrode catheter and a steerable 7F mapping and ablation catheter were placed in the systemic venous atrium, and via the retrograde route in the pulmonary venous atrium, if required. During IART pace mapping and entrainment mapping were performed in order to localize protected areas of atrial tissue between anatomical and/or surgical barriers of electrical isolation. The systemic venous atrium of 5 patients was studied using the non-contact mapping system (Ensite 3000(TM)). Linear radiofrequency current lesions were induced after mapping of electrical protected areas from the medial aspect of the superior caval vein to the systemic venous atrium and/or intraatrial baffle or the intraatrial suture line in 4 patients, from the medial aspect of mitral valve annulus to the inferior caval vein in 5 patients, from the intraatrial suture line to the posterior systemic venous atrium in 1 patient and in 2 patients from the posterior and inferior pulmonary venous atrium to the tricuspid valve annulus. Subsequently, 14 of the 15 identified IARTs were not inducible during repeated programmed stimulation. Mean duration of the electrophysiological study was 202 min, mean fluoroscopy time was 21.6 min. During follow-up (mean 20 months), 10 of 12 patients with successful procedures are free of tachycardia, 2 patients developed IARTs with a new morphology. In the majority of our patients, curative treatment was feasible by induction of linear radiofrequency current lesions by primarily targeting electrical protected areas of atrial tissue in the systemic venous atrium.
    Background: Limited data exist on training of European paediatric and adult congenital cardiologists. Methods: A structured and approved questionnaire was circulated to national delegates of Association for European Paediatric and... more
    Background: Limited data exist on training of European paediatric and adult congenital cardiologists. Methods: A structured and approved questionnaire was circulated to national delegates of Association for European Paediatric and Congenital Cardiology in 33 European countries. Results: Delegates from 30 countries (91%) responded. Paediatric cardiology was not recognised as a distinct speciality by the respective ministry of Health in seven countries (23%). Twenty countries (67%) have formally accredited paediatric cardiology training programmes, seven (23%) have substantial informal (not accredited or certified) training, and three (10%) have very limited or no programme. Twenty-two countries have a curriculum. Twelve countries have a national training director. There was one paediatric cardiology centre per 2.66 million population (range 0.87–9.64 million), one cardiac surgical centre per 4.73 million population (range 1.63–10.72 million), and one training centre per 4.29 million ...
    The population of patients with congenital heart disease (CHD) is continuously increasing with more and more patients reaching adulthood. A significant portion of these young adults will suffer from arrhythmias due to the underlying... more
    The population of patients with congenital heart disease (CHD) is continuously increasing with more and more patients reaching adulthood. A significant portion of these young adults will suffer from arrhythmias due to the underlying congenital heart defect itself or as a sequela of interventional or surgical treatment. The medical community will encounter an increasing challenge as even most of the individuals with complex congenital heart defects nowadays become young adults. Within the past 20 years, management of patients with arrhythmias has gained remarkable progress including pharmacological treatment, catheter ablation, and device therapy. Catheter ablation in patients with CHD has paralleled the advances of this technology in pediatric and adult patients with structurally normal hearts. Growing experience and introduction of new techniques like the 3D mapping systems into clinical practice have been particularly beneficial for this growing population of patients with abnorma...
    Right bundle branch block is associated with right ventricular (RV) electromechanical dyssynchrony, which may contribute to acute haemodynamic impairment after repair of tetralogy of Fallot (ToF). We sought to evaluate the effects of RV... more
    Right bundle branch block is associated with right ventricular (RV) electromechanical dyssynchrony, which may contribute to acute haemodynamic impairment after repair of tetralogy of Fallot (ToF). We sought to evaluate the effects of RV resynchronization on haemodynamics and tissue oxygenation during the first 24 h after surgery. Arterial pressures, cardiac output, and tissue oxygenation were measured in 28 consecutive patients (median age 10.1 months) during baseline sinus rhythm with right bundle branch block and after RV resynchronization by atrial-triggered RV free wall pacing in complete fusion with spontaneous activation. Studied variables were compared in a crossover design in four 5-min intervals (baseline rhythm and stimulation, 2x each). Resynchronization reduced the QRS complex duration from median 110 to 70 ms (P < 0.001), increased significantly median arterial systolic, mean and pulse pressure, cardiac index, left ventricular maximum +dP/dT and decreased central ven...
    The Pediatric and Congenital Electrophysiology Society (PACES) is a non-profit organisation comprised of individuals dedicated to improving the care of children and young adults with cardiac rhythm disturbances. Although PACES is a... more
    The Pediatric and Congenital Electrophysiology Society (PACES) is a non-profit organisation comprised of individuals dedicated to improving the care of children and young adults with cardiac rhythm disturbances. Although PACES is a predominantly North American-centric organisation, international members have been a part of PACES for the last two decades. This year, PACES expanded its North American framework into a broadly expansive international role. On 12 May, 2015, paediatric electrophysiology leaders from within the United States of America and Canada met with over 30 international paediatric electrophysiologists from 17 countries and five continents discussing measures to (1) expand PACES’ global vision, (2) address ongoing challenges such as limited resource allocation that may be present in developing countries, (3) expand PACES’ governance to include international representation, (4) promote joint international sessions at future paediatric EP meetings, and (5) facilitate a...
    Data on the results and clinical effect of an invasive risk stratification strategy in asymptomatic young patients with the Wolff-Parkinson-White electrocardiographic pattern are scarce. Eighty-five consecutive patients aged<18 years... more
    Data on the results and clinical effect of an invasive risk stratification strategy in asymptomatic young patients with the Wolff-Parkinson-White electrocardiographic pattern are scarce. Eighty-five consecutive patients aged<18 years with a Wolff-Parkinson-White pattern and persistent preexcitation at maximum exercise undergoing invasive risk stratification were retrospectively studied. Adverse accessory pathway (AP) properties were defined according to currently consented criteria as any of the following: shortest preexcited RR interval during atrial fibrillation/rapid atrial pacing≤250 ms (or antegrade effective refractory period≤250 ms if shortest preexcited RR interval was not available) or inducible atrioventricular re-entrant tachycardia. Age at evaluation was median 14.9 years. Eighty-two patients had a structurally normal heart and 3 had hypertrophic cardiomyopathy. A single manifest AP was present in 80, 1 manifest and 1 concealed AP in 4, and 2 manifest APs in 1 patient...

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