Spectrum of cardiac rhythm abnormalities and heart rate variability during the convalescent stage of dengue virus infection: a Holter study.

BACKGROUND: Various minor cardiac rhythm abnormalities have been reported in patients with dengue virus infection. Previous studies have used only random electrocardiograms (ECG) to assess the incidence of cardiac arrhythmias, and the time when the ECGs were undertaken was not systematically defined. OBJECTIVES: To evaluate cardiac arrhythmias and heart rate variability in children with dengue virus infection during the convalescent stage using Holter monitoring. METHODS: Overnight 18-24-hour Holter monitoring was performed in 35 children [mean (SD) age 11·7 (2·3) y] at least 24 hours after defervescence (on the last day of admission). In 17 patients, time- and frequency-domain short-term (5 minutes) heart rate variability (HRV) during the convalescent stage was also compared with the value obtained during the follow-up visit (at least 14 days after defervescence). RESULTS: During the convalescent stage, cardiac rhythm abnormalities were found in ten patients (29%), including sinus pause (1), first-degree (2) and Mobitz type I second-degree AV block (Wenckebach) (3) and atrial (4) and ventricular ectopic beats (5). There was no relationship between the clinical severity of dengue virus infection (DF, DHF without shock and DSS) and the incidence of cardiac arrhythmia. There was no significant difference in the averaged RR interval, the time-domain HRV (SDNN, RMSSD, pNN 50) or frequency-domain HRV (LF, HF, LF/HF ratio) between the convalescent stage and at follow-up. CONCLUSION: Various benign bradyarrhythmias and ectopic beats are detected in patients with dengue virus infection during the convalescent stage.

Increased level of hepatocyte growth factor in children with dengue virus infection.

BACKGROUND: Evidence of hepatocellular damage is common in dengue-infected individuals. Hepatocyte growth factor (HGF), a key cytokine responsible for liver regeneration, may play a prognostic role in dengue virus infection. AIM: To determine the relationship between serum HGF level and disease severity in patients with dengue virus infection. METHODS: Serum samples from 27 children [17 dengue fever (DF), ten dengue haemorrhagic fever (DHF)] with serologically confirmed dengue virus infection during the febrile, toxic stages and at follow-up were analysed for HGF. Serum samples obtained from nine healthy children served as the control group. RESULTS: In dengue-infected patients, serum HGF was significantly higher at the febrile and toxic stages than at follow-up (p<0.05). In comparison with DF, patients with DHF had a greater level of HGF at the febrile stage (p<0.05). A cut-off HGF level of 1220 pg/mL obtained during the febrile stage showed a sensitivity of 90% and a specificity of 53% for predicting clinical progression to DHF (area under the ROC curve 0.75). CONCLUSION: Serum HGF level at the early stage of dengue virus infection is elevated and may be a useful predictor for clinical progression to DHF.

Complete heart block in children at King Chulalongkorn Memorial Hospital.

The etiologies of complete heart block in thirty-one children (mean age 5.5 +/- 5.2 years, range 0-14 years) diagnosed at King Chulalongkorn Memorial Hospital between 1990-2001 were reviewed. Three main groups of patients were identified: 1) patients who presented in utero or in the newborn period (congenital heart block, n = 6), 2) patients who had complete heart block after cardiac surgery (postoperative heart block, n = 10), and 3) children outside the newborn period with a new diagnosis of complete heart block unrelated to cardiac surgery (unknown etiology, n = 15). Among 15 patients in the last group, 5 were asymptomatic (or minimally symptomatic) with complete heart block unexpectedly found. These patients probably had previously undetected congenital heart block. Two patients had complete heart block associated with mild viral illness, but no bradycardia-related symptom. The etiology for heart block in these 2 patients was unknown. Eight patients probably had recent onset heart block because of new bradycardia-related symptoms, or a previously documented normal heart rate. All patients in this group were female (mean age 4.3 +/- 4.3 years, median 3.5 years). All were diagnosed between August and January, and the majority (75%) had a history of non-specific viral illness in the preceding 2 weeks. Seven patients (87.5%) were acutely symptomatic. Syncope and/or seizure were the most common presenting symptoms. Left ventricular systolic dysfunction was found in only one patient. The etiology of complete heart block in these patients probably was an acute viral myocarditis that preferentially affected the conduction system. Two of these eight patients had complete recovery of the atrioventricular conduction. The rest had no improvement or had only partial recovery and subsequently underwent permanent cardiac pacemaker insertion.

Atrial tachycardia from enhanced automaticity in children: diagnosis and initial management.

Ten patients (aged 0-9 years) with the diagnosis of automatic atrial tachycardia (AAT) from August 1997 to August 2000 were reviewed. Three patients had paroxysmal (repetitive) AAT and the tachycardia was incessant in six (defined as presence of AAT for more than 90% of the time). The type of AAT in one patient was unknown. Four patients presented with congestive heart failure (CHF), one with pre-syncope, one with palpitation, and four were asymptomatic. Six patients (60%) had depressed left ventricular ejection fraction. All patients with CHF had incessant AAT with atrial rate > 220/min and ventricular rate > 200/min at admission. After treatment with antiarrhythmic medications, all patients had adequate control of the AAT (9 had complete elimination of AAT and 1 partial control). Amiodarone (alone, or in combination with digoxin) was effective in 5 of 6 cases (83%), although complete elimination of the AAT was usually delayed (median = 5 days, range 30 minutes to 17 days). Other effective medications were digoxin, digoxin + propranolol and atenolol (all in patients who did not have CHF on presentation). At the time of this report, 3 patients had no AAT off antiarrhythmic medication, 5 patients were still receiving treatment (with good control) and 2 patients died from sepsis during the same admission even though AAT was controlled. All surviving patients had normal ventricular ejection fraction on follow-up. AAT in children is rare, but when it occurs in persistent form at a fast rate, it is usually associated with CHF and is difficult to treat. Amiodarone (+/- digoxin) effectively controls the arrhythmia in the majority of cases, although full effect may take several days. With successful treatment, most patients do well and some can be taken off the medication(s) without recurrence of the arrhythmia.

Nonfluoroscopic three-dimensional mapping for arrhythmia ablation: tool or toy?

INTRODUCTION: Conventional mapping and ablation rely on fluoroscopy, which can result in imprecise positioning of the ablation catheter and long fluoroscopic exposure times. We evaluated a nonfluoroscopic three-dimensional mapping system, termed CARTO, and compared the results of ablation using this technique with those of conventional mapping. METHODS AND RESULTS: We compared the results of 88 arrhythmia ablations (79 patients) using CARTO with 100 ablations (94 patients) using the conventional technique. The ablations were separated into four groups: (1) AV nodal reentrant tachycardia (AVNRT); (2) atrial tachycardia/flutter; (3) ventricular tachycardia (VT); and (4) bypass tract tachycardia. We compared the success rate, complications, and fluoroscopy and procedure times. The ablation outcomes were excellent and comparable in all four types of the arrhythmias between the two techniques. Major complications included one cardiac tamponade in each group and one second-degree AV block in the conventional group. Fluoroscopy time was shorter using the CARTO technique: 10+/-7 versus 27+/-15 minutes for AVNRT (P < 0.01), 18+/-17 versus 44+/-23 minutes for atrial tachycardia and flutter (P < 0.01), 15+/-12 versus 34+/-31 minutes for VT (P < 0.05), and 21+/-14 versus 53+/-32 minutes for bypass tract tachycardia (P < 0.01). Procedure times were similar except for the bypass tract patients, which was shorter in the CARTO group, 4+/-1.3 versus 5.5+/-2.5 hours (P < 0.01). CONCLUSION: The electroanatomic three-dimensional mapping technique reduced fluoroscopy time and resulted in excellent outcome without increasing the procedure time.

Impact of respiratory syncytial virus infection on surgery for congenital heart disease: postoperative course and outcome.

OBJECTIVES: a) To describe the postoperative course and outcome of cardiac surgery in children with recent respiratory syncytial virus (RSV) infection; and b) to evaluate whether timing of surgery has any impact on the outcome. DESIGN: Retrospective case series. SETTING: Intensive care unit and medical and surgical wards of a teaching pediatric hospital. PATIENTS: Twenty-five children (aged 25 days to 3.5 yrs; median, 4 months) with congenital heart disease who had cardiac surgery within 6 months after RSV infection. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We reviewed the clinical course and outcome of all patients. The cardiac diagnoses included ventricular septal defect (n = 11), tetralogy of Fallot (n = 3), atrioventricular canal (n = 3), and others (n = 8). Thirteen patients had surgery during the same admission as RSV infection (group I), and 12 patients had surgery electively after being discharged to home after RSV infection (group II). Two patients in group I died; both of these patients had undergone total repair of tetralogy of Fallot within 2 wks after admission for RSV infection. Postoperative complications in group I patients included pulmonary hypertension (n = 5), adult respiratory distress syndrome (n = 1), tracheal stenosis (n = 1), left ventricular dysfunction (n = 1), pericardial effusion (n = 1), secondary bacterial or fungal infection (n = 7), and deep venous thrombosis (n = 1). Of all group I patients, the ones who were operated on early appeared to be at higher risk for complications, especially for postoperative pulmonary hypertension. No patient in group II died, and only two patients had minor complications (one had reactive airway disease, and the other had a transient superior vena cava syndrome after a bidirectional Glenn operation). CONCLUSIONS: Cardiac surgery performed during the symptomatic period of RSV infection is associated with a high risk of postoperative complications, especially postoperative pulmonary hypertension. These complications appeared to be more frequent and of greater severity in patients who had earlier surgery compared with those who had later surgery. More studies are needed regarding the proper timing of cardiac surgery in patients with congenital heart disease and RSV infection.

Effects of cisapride on QT interval in children.

Recent reports of torsade de pointes and heart block associated with prolonged QT interval in children receiving cisapride raise questions about its safety. We prospectively examined the effects of cisapride on the QT interval in children. Electrocardiography was performed on 30 children before and after cisapride was administered. An additional 71 children underwent electrocardiography only after starting cisapride. The incidence of a corrected QT (QTc) interval > 440 msec or a marked abnormality in T wave morphology was determined in all 101 children. Cisapride significantly lengthened the QTc with a mean increase of 15.5 +/- 4.6 msec (mean +/- SEM, p = 0.002 in the 30 children with baseline electrocardiographs. Twelve of the 101 patients were found to have a QTc > 440 msec, and one had a new prominent notched T wave in all leads. In these 13 (13%) patients with repolarization abnormalities, other factors that might contribute to a long QT were noted in 11 (85%) patients. We conclude that cisapride use in children is associated with a modest increase in QT interval. The incidence of QTc > 440 msec is low. Most children with long QTc have other factors that could compound the effects of cisapride.

Severe pulmonary hypertension as a cause of reverse aortic arch flow in the neonate: report of two cases.

We describe two newborn infants with severe pulmonary hypertension and circulatory collapse. In both cases, pulsed and color flow Doppler studies showed systolic and diastolic reversal of flow in the transverse aortic arch to the level of the innominate artery. No associated cardiac or noncardiac anomalies could explain the reverse flow in the aortic arch. Severe pulmonary hypertension and low left ventricular output were thought to be responsible for the Doppler findings. Reversal of the aortic arch flow in the newborn with pulmonary hypertension may be associated with a poor prognosis, and early consideration of extracorporeal membrane oxygenation in such patients may be indicated.