Accelerated idioventricular rhythm resulting in torsades de pointes and cardiac arrest in a child: successfully cryoablated in left'coronary cusp.

Known as a benign arrhythmia and normally requiring no specific treatment, accelerated idioventricular rhythm can rarely degenerate to a life-threatening arrhythmia. Here, we present a child with left coronary cusp-originating accelerated idioventricular rhythm, degenerating into torsades de pointes and resulting in cardiac arrest, which was ablated with a cryocatheter. An 11-year-old boy, followed due to asymptomatic accelerated idioventricular rhythm before, was referred to our department because he had experienced an aborted cardiac arrest during sleep. He had been resuscitated for 5 minutes. Twenty-four-hour Holter-ECG revealed incessant accelerated idioventricular rhythm, consisting up to 90% of the whole record and two torsades de pointes attacks, triggered by accelerated idioventricular rhythm-induced "R on T" phenomenon, and resulting in syncope and cardiac arrest. Transthoracic echocardiography revealed no structural cardiac defect but mild left ventricular systolic dysfunction with an ejection fraction of 45% and shortening fraction 23%. An electrophysiologic study was conducted, and accelerated idioventricular rhythm focus was mapped to left aortic coronary cusp. A cryocatheter with an 8-mm tip was preferred for successful ablation of the accelerated idioventricular rhythm focus, due to close neighbourhood to coronary ostium. The patient was discharged in 3 days without any premature ventricular contractions or accelerated idioventricular rhythm and with normalised cardiac functions. After 9 months on follow-up, he was still asymptomatic, without any premature ventricular contractions or accelerated idioventricular rhythm and with normal cardiac functions. Although the clinical course of accelerated idioventricular rhythm is known as benign, accelerated idioventricular rhythm can rarely degenerate to a life-threatening arrhythmia. In such cases, electrophysiologic study and catheter ablation are a good option in such cases with accelerated idioventricular rhythm for an ultimate cure.

Electrocardiographic and electrophysiologic effects of dexmedetomidine on children.

BACKGROUND: Dexmedetomidine (DEX) is a highly selective alpha-2-adrenergic agonist approved for short-term sedation and monitored anesthesia care in adults. Its effects on the electrocardiography and cardiac conduction tissue are not well described in the literature. Therefore, we aimed to characterize the electrocardiographic and electrophysiologic effects of DEX in children. METHODS: Twenty children (11 boys and nine girls) between the ages of eight and 17 undergoing electrophysiology study and ablation of the supraventricular tachycardia had hemodynamic and cardiac electrophysiologic variables measured before and during the administration of DEX (1 microgram/kg IV over 10 minutes followed by a 10-minute continuous infusion of 0.5 microgram/kg/h). RESULTS: A significant decrease in heart rate was seen after the administration of DEX, but the systolic-diastolic-mean arterial pressure, respiratory rate, and end-tidal carbon dioxide did not change. Corrected sinus node recovery times and baseline sinus cycle lengths, which are markers of sinus nodal function, were both lengthened with the administration of DEX. Atrioventricular (AV) nodal function, as evidenced by the Wenckebach cycle length, the ventriculoatrial block cycle length, and AV nodal effective refractory periods, was lengthened significantly. We also found that DEX increased the atrial refractory period and diminished atrial excitability. CONCLUSIONS: DEX significantly depressed sinus and AV nodal function in pediatric patients without significant electrocardiogram interval changes, other than a trend toward lower heart rates. Although no spontaneous AV nodal block and no clinically significant bradycardia were seen, we recommend that DEX be used with caution in patients at risk for bradycardia and/or AV nodal dysfunction due to its associated comorbidities.

Electroanatomic mapping guided cryoablation of Mahaim pathways in children with limited fluoroscopy exposure.

BACKGROUND: The presence of Mahaim accessory pathways (MAP) with anterograde decremental conduction is a disorder that leads to antidromic atrioventricular reentrant tachycardia. There are rare reports of cryoablation use in MAP. This study aims at sharing our experience with using cryoablation to treat MAP in children. METHODS: Electrophysiology study and catheter ablation were performed in 14 patients diagnosed with Mahaim tachycardia between January 2010 and December 2013. Cryoablation was used in nine of the cases. A three-dimensional navigation system with surface electrode patches (EnSite System, St. Jude Medical Inc., St. Paul, MN, USA) was used for all procedures. RESULTS: The patients (two girls and seven boys) had a median age of 11.5 years (8-18 years) and a median weight of 67 kg (31-80 kg). Mahaim conduction was localized in the right posterolateral (n = 4), right lateral region (n = 2), right posteroseptal (n = 1), right anterolateral (n = 1), and right anterior (n = 1). A pathway potential was noted in six of nine cases at the tricuspid annulus. Catheter choices and acute success rates were as follows: cryoablation in four (three of four successful), radiofrequency catheter ablation (RFA) and cryoablation in five (successful in four of five). No fluoroscopy was used in six of nine patients. The mean procedure duration was 249 ± 90 minutes. No major complications were observed. The final long-term success rate for cryoablation was seven of nine (78%). CONCLUSIONS: Cryoablation can be used as a reliable and effective alternative to RFA in the treatment of Mahaim accessory conduction pathways in children. Prospective comparative studies are necessary in order to further evaluate the long-term efficacy of this method.

Cryoablation of anteroseptal accessory pathways in children with limited fluoroscopy exposure.

Due to its safety profile, cryoablation is used increasingly in pediatric patients, especially for septal arrhythmia substrates. Recent advances in electroanatomical-mapping technologies have resulted in a decrease or complete elimination of fluoroscopy exposure during catheter ablation procedures. The aim of this study was to assess the efficacy and safety of cryoablation of anteroseptal accessory pathways (APs) using electroanatomical-mapping system guidance with limited fluoroscopy exposure. A total of 24 patients underwent cryoablation of anteroseptal APs between July 2010 and April 2012. Cryomapping was performed with a 6 mm-tip catheter at -30 °C before the lesions were delivered. An 8 mm-tip catheter was used in one patient. The EnSite system (St. Jude Medical, St Paul, MN) was used in all procedures. The mean age was 11.9 ± 4.3 years. Acute success rate was 95.8 % (23 of 24). The mean procedure and cryoablation durations were 168 ± 58 min and 1,463 ± 525 s, respectively. Limited fluoroscopy was used only in 7 patients, and the mean fluoroscopy time was 1.7 ± 1.8 min (range 0.1-4 min) in these patients. Recurrence was noted in 2 patients (8.7 %) who underwent a second successful cryoablation procedure. The patient who underwent a failed attempt during the first procedure was successfully treated with a repeat procedure. The resultant long-term success rate was 100 % at a mean follow-up period of 14.2 ± 7.7 months. There were no complications except for transient atrioventricular block in one patient. Cryoablation of anteroseptal APs can be performed effectively and safely in children using a limited fluoroscopic approach with the help of electroanatomical-mapping systems.

[Dilated cardiomyopathy associated with dystrophic epidermolysis bullosa: role of micronutrient deficiency?]. / Distrofik epidermolizis bülloza ile iliskili dilate kardiyomiyopati: Mikrobesin eksikligi mi?

Autosomal recessive dystrophic epidermolysis bullosa (DEB) is a chronic skin disorder characterized by widespread bullous formation, erosions, and scar formation. There have been reports of dilated cardiomyopathy and death in patients with DEB. The pathogenesis of cardiomyopathy in DEB remains uncertain, but some drugs, viral infections, iron loading, micronutrient deficiencies such as selenium and carnitine have been implicated. A 16-year-old boy who was followed-up from birth with the diagnosis of DEB presented with respiratory distress and heart failure symptoms of two-week history and early fatigue within the past year. Etiological evaluation showed a low plasma selenium level. Echocardiographic examination yielded the diagnosis of dilated cardiomyopathy. Findings of viral serology tests and metabolic screening were normal. Selenium replacement and anticongestive treatment were initiated, which led to partial improvement in cardiac functions. The authors draw attention to the possible role of micronutrient deficiency in the development of cardiomyopathy in patients with DEB.

Effect of vitamin C on oxidative liver injury due to isoniazid in rats.

BACKGROUND: The aim of the present study was to investigate the effect of different doses of vitamin C on oxidative liver injury due to isoniazid (INH) in rats. METHODS: Rats were divided into four subgroups, each containing 10 rats. Group 1 was the control group; group 2, INH 50 mg/kg per day; group 3, INH 50 mg/kg per day + low-dose vitamin C (100 mg/kg per day); group 4, INH 50 mg/kg per day + high-dose vitamin C (1000 mg/kg per day). INH and vitamin C were administered into their stomachs through an oral tube. After 21 days, measurements were made in both serum and homogenized liver tissues. The levels of glutathione (GSH), superoxide dismutase (SOD) and other biochemical variables were measured. Malondialdehyde (MDA), glutathione peroxidase (GSH-px) and vitamin C were measured using commercial kits. RESULTS: Aspartate amino transferase and alanine aminotransferase in group 2 were higher than those in groups 1, 3 and 4 (P < 0.008 for both). Serum and tissue levels of MDA in group 2 were higher than that in groups 1 and 3 (P < 0.008 for both). There was no difference in the SOD levels between the four groups (P= 0.095). Erythrocyte and tissue GSH in group 2 were higher than that in groups 1 and 3 (P < 0.008 for both). Interestingly, erythrocyte and tissue GSH in group 4 were lower than those in group 1 (P < 0.008 for both). Erythrocyte level of GSH-px in group 2 was higher than that in groups 1 and 3 (P < 0.008 for both). CONCLUSIONS: INH-induced liver injury is associated with oxidative stress, and co-administration of low-dose vitamin C may reduce this damage effectively in a rat model. The antioxidant effect of high-dose vitamin C does not seem more potent compared to the low dose.