Antiarrhythmic therapy was first started with drug therapy. However, the CAST　（cardiac arrhythmia suppression trial）　study revealed that antiarrhythmic agents had a proarrhythmic effect on patients with asymptomatic ventricular premature beats, and increased the risk of death from arrhythmias. The use antiarrhythmic medications were modified from an empirical to scientific use after the Sicilian Gambit study. Radiofrequency catheter ablation was started in about the same era. It widely spread throughout the world, together with the progression of the technology of 3D mapping systems. Also, device therapies such as implantable cardioverter defibrillators, and cardiac resynchronization therapy have become available and contributed to the prevention of sudden cardiac death.Another issue to note is the advancement of genetic screening for inherited arrhythmias. Many gene anomalies have been found in long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, short QT syndrome, progressive cardiac conduction defects, familial sick sinus syndrome, and familial atrial fibrillation. From these gene analyses, the affected channels can be defined, and specific effective medications can be selected.

View full abstract

Purpose: There have been few reports of nifekalant (NIF) for the management of arrhythmias in children, and its efficacy and safety remains to be established. We studied children treated with NIF in our institution.
Methods: The subjects were 28 patients (6 days to 18 years old; 20 males and 8 females) who received NIF. NIF was used to manage postoperative arrhythmias in 25 patients with congenital heart disease and in 3 patients with cardiomyopathy. We retrospectively studied the antiarrhythmic effectiveness and characteristics of patients with torsades de pointes (Tdp).
Results: NIF effectively controlled arrhythmias in 25 patients (89%), but induced Tdp in 5 patients (18%). QT intervals corrected by Bazett's formula (QTc[B]) and Fridericia's formula (QTc[F]) were both significantly longer in patients with Tdp than in those without Tdp (median, 585 vs. 460 msec, p = 0.001 and median, 535 vs. 410 msec, p = 0.001, respectively). Receiver-operating-characteristic curve analysis showed that the cutoff point of QTc (B) values for Tdp was 531 msec and that of QTc (F) values for Tdp was 460 msec.
Conclusion: Our results suggest that NIF is effective for arrhythmias in children, but the development of Tdp should be carefully monitored, especially when QTc (B) values are 531 msec or longer or QTc (F) values are 460 msec or longer.

View full abstract

Background: The ductus arteriosus (DA), a fetal arterial connection between the main pulmonary artery and the descending aorta, normally closes immediately after birth. The oxygen concentration in the blood rises after birth; in the DA, this increase causes functional closure, which is induced by smooth muscle contraction. Previous studies have demonstrated that hypoxia and/or oxygenation affect vascular remodeling. Therefore, we hypothesized that the rise in oxygen concentration would affect the vascular structure of the DA by producing proteins secreted from DA smooth muscle cells (SMCs).
Method and Results: We performed LC-MS/MS analyses to comprehensively investigate the secreted proteins in the supernatants of rat DA SMCs that were harvested under a hypoxic condition (1% oxygen) or under a normoxic condition (21%oxygen). We found that the rise in oxygen concentration reduced the secretion of elastin from DA SMCs. Reverse transcriptionpolymerase chain reaction analyses also revealed that the expression levels of elastin mRNA were down-regulated in DA SMCs from a hypoxic to a normoxic condition.
Conclusion: Our in vitro study demonstrated that the rise in oxygen concentration reduced the secretion of elastin. Because elastin forms internal elastic lamina and elastic fibers in the vascular muscle layers, this study suggests that the rise in blood oxygen concentration after birth reduces the secretion of elastin, which may play a role in DA structural remodeling after birth.

View full abstract

Background: Bidirectional cavopulmonary shunts (BCPS) in univentricular heart often cause elevated transpulmonary gradient (TPG) and oxygen desaturation in the acute postoperative period, presumably due to adaptive failure to the new pulmonary circulation. Sildenafil, a PDE5 inhibitor, is widely used as a promising selective pulmonary vasodilator in the treatment of postoperative severe pulmonary hypertension. We tested the hypothesis that sildenafil ameliorates impaired pulmonary circulation after BCPS.
Method: Sildenafil treatment was indicated when TPG was elevated more than 10 mmHg with oxygen desaturation occurred despite high FiO₂ upon completion of BCPS. Sildenafil was administered by enema at a starting dose of 0.5 mg/kg following admission to the ICU. The dose was carefully increased stepwise by 0.5 mg/kg every 4 hours up to a maximum of 2 mg/kg. We retrospectively reviewed eight patients of BCPS treated with sildenafil. Age: 7.5 months (5-50); BW: 6.5 kg (5.7-13.8); diagnosis: DILV-3; unbalanced AVSD/hypoplastic LV-3; PA/IVS-1; and ccTGA/hypoplastic LV-1.
Results: Mean pulmonary artery pressure and TPG significantly decreased with hemodynamic improvement after sildenafil administration from 18.1 ± 3.1 to 11.5 ± 2.6 mmHg (p < 0.05) and 12.6 ± 1.5 to 7.4 ± 2.4 mmHg (p < 0.05), respectively. Oxygenation indicated by PaO₂ / FiO₂ ratio improved significantly after sildenafil administration from 56.3 ± 18.8 to 149.2 ± 52.5 (p < 0.05). None of the patients required nitric oxide inhalation, and no significant adverse events occurred.
Conclusion: Sildenafil is a safe and effective treatment in the postoperative management of acute maladaptive pulmonary circulation after BCPS.

View full abstract

Background: Electrocardiographic findings of atrial septal defects (ASD) include right bundle branch blocks (RBBB), isolated negative T-waves, discontinuous T-waves in the chest leads, and a notch in the inferior limb leads (crochetage pattern). The aim of the present study was to determine the usefulness of a crochetage pattern for indicating the presence of ASD.
Method: We retrospectively reviewed the electrocardiograms of (1) 59 patients with ASD who underwent catheterization between 2002 and 2012 and (2) 60 subjects who showed RBBB in school heart examination from 2007 to 2012.
Results: (1) Electrocardiograms of the patients with ASD indicated a crochetage pattern in 41 cases. There was no significant difference in the pulmonary-to-systemic blood flow ratio (Qp/Qs) and the right ventricular end diastolic volume between the patients with the crochetage pattern and those without it. Preschool children had lower positive rates of the crochetage pattern than all other age groups.(2) ASD was detected in 10 of 60 subjects. A finding of a crochetage pattern with RBBB was highly sensitive for detection of ASD, while a finding of discontinuous T-waves with RBBB was highly specific.
Conclusion: A finding of a crochetage pattern and discontinuous T-waves in combination with RBBB may enable the highly accurate detection of ASD.

View full abstract

Background: There are no reports describing the outcome that exceed ten years of follow-up in children undergoing percutaneous radiofrequency catheter ablation (CA) of WPW syndrome. This study clarified the long-term follow-up results of the CA of WPW syndrome and the acute and mid-term results.
Methods: Between 1992 and 2001, 184 consecutive patients (104 males, 80 females, 6 months to 19 year-old [median: 13 years-old]) without any structural heart disease underwent CA of WPW syndrome were included, and underwent a total of 219 procedures. The acute and mid-term results were analyzed from the medical records and the long-term results were analyzed by questionnaires.
Result: Ninety-percent of the patients had atrioventricular reciprocating tachycardia before the CA. The accessory pathways （AP） were left-sided in 52% , septal in 16% , right-sided in 26% , and at multiple sites in 6% . The rates of an acute success, recurrence, and failure were 94% , 13% , and 6% , respectively. The rate of a success without a recurrence was significantly lower for right-sided APs than left-sided APs. The overall mid-term follow-up (median 44 months) success rate was 96% . The long-term results (median: 165 months) revealed no recurrences, and the patient satisfaction rate was 98%. None of the patients, except for one, had a recurrence within one year post-CA. Complications occurred in six patients including complete atrioventricular block (CAVB) in one, transient CAVB in one, complete right bundle branch block in three, and aortic insufficiency in one, who did not require any treatments, such as pacemaker implantation or medical treatment.
Conclusions: The long-term results of the CA of WPW syndrome in children were as good as the acute and mid-term follow up results. Rare, but severe complications, such as complete atrioventricular block or recurrences within one year after the CA, occurred. Our goal is to improve the safety and success rate.

View full abstract

A 3-year-old girl with Ebstein's anomaly lapsed into sinus node dysfunction and junctional rhythm after the Fontan-type procedure. Following temporary atrial pacing for 4 weeks then cilostazol and theophylline to promote improvement of sinus node function, her cardiac rhythm showed sinus while awake and junctional during sleep and she had edema and coldness of extremities early in the morning. Pulsed-Doppler echocardiography revealed the absence of A-wave on transmitral flow, decreased systolic fraction in area and increased PVA-wave peak velocity on pulmonary venous flow. Loss of atrioventricular (AV) synchrony seemed to deteriorate both booster pump function and reservoir function of the atrium. Cardiac catheterization was performed to compare hemodynamic measurements during junctional rhythm with during transesophageal atrial pacing which mimics sinus rhythm. Mean central venous pressure was similar in both, however, spike pressure waveforms were present in the superior vena cava and the inferior vena cava during junctional rhythm. Cardiac index and arterial pressure were decreased during junctional rhythm, compared to transesophageal atrial pacing. After undergoing permanent pacemaker implantation, she was relieved from congestive heart failure. This case shows the importance of AV synchrony, that is, the maintenance of appropriate cardiac rhythm for a higher quality Fontan physiology.

View full abstract

The use of cardiac resynchronization therapy (CRT) is increasing for adult patients with heart failure refractory to pharmacological therapy. However, the use of CRT in pediatric patients has been limited, hence its benefits are largely unknown. A five-month-old boy presented with failure to thrive over a period of 2 months and was subsequently diagnosed with idiopathic dilated cardiomyopathy (IDCM) on echocardiogram, showing severe left ventricular dysfunction and dilatation. Pharmacological therapy, including diuretics, ACE inhibitor, and beta-blocker, was initiated, but resulted in only a moderate decrease in plasma brain natriuretic peptide (BNP) from 3,550 pg/ml to 1,050 pg/ml, without improvement in weight gain. Since the heart failure was resistant to medical therapy and ventricular dyssynchrony was evident on echocardiogram, biventricular DDD pacemaker was implanted at the age of 16 months. The CRT clearly improved his clinical symptoms, with normal weight gain and normalized plasma BNP over the following 10 months. The size and function of the left ventricle also normalized with reduced dyssynchrony.In summary, we present the impressive effects of CRT in a one-year-old boy with IDCM induced refractory heart failure. This case suggests that early identification of ventricular dyssynchrony and instigation of CRT may be a promising therapeutic strategy for pediatric patients with severe heart failure, including IDCM.

View full abstract

Beriberi-heart disease is rare in advanced countries, so accurate diagnosis may be elusive. We present the case of a 2 year-old girl with mild mental developmental disability who developed beriberi-heart disease, presenting with dyspnea, right-sided heart failure, and pulmonary hypertension after she caught a cold. This patient was abnormally fastidious about her food and fluid intake： she would not eat almost exclusively. When admitted to our hospital, her serum thiamine level was remarkably depressed. We were certain she was free from other diseases that can cause pulmonary hypertension. After receiving a thiamine supplement, cardiac function was improved and pulmonary pressure became normal. Neurological symptoms (e.g. hypotonia, lack of deep tendon reflex) also improved. This patient appeared to have secondary pulmonary hypertension induced by thiamine deficiency, based on a complete cure after nutritional status improved.

View full abstract

Case: Six-month-old infant with large ventricular septal defect (VSD) who underwent pulmonary artery banding as a part of initial surgery. He had a dying spell due to tracheal compression by dilated right pulmonary artery. Therefore, an emergency VSD repair and aortopexy were performed. Thereafter, peripheral vascular catheter-related blood stream infection due to Methicillin-resistant Staphylococcus aureus (MRSA) occurred andLed to infective endocarditis with vegetation on tricuspid valve. Antimicrobial therapy centering on vancomycin (VCM) was initiated. However, VCM minimum inhibitory concentration of isolates changed from 1 to 2 μg/mL and bacteremia did not improve even though the trough level of VCM was within recommended therapeutic concentrations. We suspected the presence of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA), and teicoplanin (TEIC) was started instead of VCM. In addition, albekacin (ABK) and (linezolid) LZD were added on. Thereafter, bacteremia improved and only transient reticulocytopenia and anemia were confirmed as an adverse effect of the therapeutic drug. The multidrug therapy can be an alternative for refractory infective endocarditis due to drug resistant Staphylococcus aureus under adequate therapeutic drug monitoring (TDM).

View full abstract