Moderate hypothermia in the management of resistant automatic tachycardias in children.

BACKGROUND--Automatic focus tachycardias are often resistant to electrical and pharmacological treatment. Moderate systemic hypothermia (32-34 degrees C) may reduce the tachycardia rate in children with His bundle tachycardia after cardiac surgery. METHODS--The case notes of seven children with automatic focus tachycardias treated with hypothermia were reviewed. Six had His bundle tachycardia after cardiac surgery and one had ectopic atrial tachycardia; all had signs of low cardiac output. RESULTS--Hypothermia led to a reduction in heart rate in all patients (from 211 (28) (mean (SD] to 146 (5) beats/minute, p less than 0.001), with rises in systolic blood pressure (from 74 (14) mm Hg to 97 (10) mm Hg, p less than 0.01) and hourly urine output (from 0.5 (0.4) ml/kg to 4.6 (2.8) ml/kg, p less than 0.02). No direct adverse effects were noted. The arrhythmia did not resolve in three children, who died (two with His bundle tachycardia after Fontan procedures and one with ectopic atrial tachycardia); the other four regained sinus rhythm which was maintained at follow up of 3-13 (mean 9) months. CONCLUSIONS--Moderate systemic hypothermia led to slowing of the arrhythmia rate and an improvement in cardiac output in patients with resistant automatic focus tachycardias. It can be used to improve the haemodynamic condition while other measures of arrhythmia control are being pursued or until spontaneous recovery of normal rhythm.     

Impact of curative ablation on pharmacologic management in children with reentrant supraventricular tachycardias

BACKGROUND: The introduction of radiofrequency catheter ablation as a curative treatment option has led to a much better outlook for children with recurrent supraventricular reentrant tachycardias (SVT). This study sought to evaluate the impact of ablation on pharmacologic treatment of SVT. METHODS: Two time periods were retrospectively compared with regard to number of episodes of SVT in different age groups, number of acute drug conversions of SVT, chronic antiarrhythmic drug treatments prescribed: in the first period (1989-1994) management of SVT was exclusively pharmacological whereas during the second period (1995-2000) ablation was an option for patients aged 5 years or older. RESULTS: The study included 88 pediatric patients with recurrent SVT, 40 in the first period, 48 in the latter. Of these, 16 children (all >5 years of age) had an ablation procedure during the second time period. In patients aged >5 years, the number of documented SVT fell from a mean of 3.7/patient to two episodes. The number of acute drug conversions of SVT decreased from a mean of 1.1/patient to 0.2 (p<0.05) during the second period. In the group of children aged >5 years chronic antiarrhythmic treatment was given during a mean of 15 months/patient in period one compared to 4.6 months (p<0.05) in the second period. CONCLUSION: In the current era with increasing use of ablation as first-line treatment in older children with recurrent SVT, acute as well as chronic pharmacologic intervention for SVT has become significantly less frequent.     

Surgical treatment of supraventricular tachycardias in children]

The paper deals with the results of surgical treatment in 19 children with supraventricular tachycardias. Eighteen patients were found to have the Wolff-Parkinson-White syndrome and one presented with ectopic right atrial tachycardia. The accessory pathways in the free wall and anterior septum in the presence of the Wolff-Parkinson-White syndrome were eliminated on the working heart, whereas those in the posterior septum were removed during extracorporeal circulation via endocardial access. Ectopic right atrial tachycardia was arrested by arrhythmogenic area resection in the right atrium during extracorporeal circulation. A positive result of the operation was achieved in 17 of the 18 patients. At day 2 of postsurgery, one patient developed recurrent tachycardia that was eliminated during a repeated operation. Which optimal method should be chosen to remove accessory pathways is discussed in the paper.     

射频消融治疗儿童室上性心动过速

目的 :探讨射频消融 （RFCA）在治疗儿童室上性心动过速 （SVT）中的应用价值。方法 :回顾分析唐都院近 5年接受 RFCA治疗的 4 9例患儿的疗效。结果 :房室折返性心动过速 （AVRT） 38例 ,占 77.6 % ;其中左侧房室旁路2 9例 ,右侧房室旁路 9例 ,房室结折返性心动过速 （AVNRT） 11例 ,占 2 2 .4 %。全部消融成功。术后无 1例复发 ,亦无严重并发症。结论 ;AVRT和 AVNRT是儿童 SVT中最常见类型 ;RFCA是治疗儿童 SVT安全、有效的方法     

Clinical antiarrhythmic effects of amiodarone in patients with resistant paroxysmal tachycardias.

Oral amiodarone, an iodine-containing antiarrhythmic agent, was administered to 72 patients with recurrent paroxysmal tachycardias. Thirty-nine patients had tachycardias associated with the Wolff-Parkinson-White syndrome, 15 patients had paroxysmal atrial fibrillation unassociated with the Wolff-Parkinson-White syndrome, and 18 patients had ventricular tachycardia. In all patients, the frequency of symptomatic attacks had not been reduced by at least three other antiarrhythmic agents alone or in combination. The response to amiodarone treatment was graded according to the patients' subjective response (total suppression, partial suppression, and no effect). Overall, 57 per cent of patients had total abolition of attacks and another 22 per cent had a partial suppression of attacks. Side effects, the most common of which were photosensitivity and gastrointestinal upsets, occurred in 44 per cent and were sufficiently severe to warrant withdrawal of treatment in 15 per cent. These results confirm that amiodarone is of considerable value in the treatment of recurrent paroxysmal arrhythmias resistant to other drugs.     

Intravenous flecainide acetate for the clinical management of paroxysmal tachycardias

Intravenous flecainide acetate (2 mg/kg) was administered to 40 patients undergoing routine electrophysiological evaluation for the investigation of recurrent paroxysmal tachycardias. Ten patients had recurrent atrial flutter, 11 patients had recurrent atrial fibrillation, one of whom also had paroxysmal left atrial tachycardia, and 19 patients had recurrent ventricular tachyarrhythmias (17 with recurrent ventricular tachycardia and 2 with recurrent fascicular tachycardia). Flecainide was administered during tachycardia (over 5 to 10 minutes) to all patients with atrial flutter, to 10 patients with atrial fibrillation, and to 17 patients with ventricular tachyarrhythmias. In the remaining 3 patients with ill-sustained arrhythmias flecainide was administered during sinus rhythm and reinitiation of tachycardia was then attempted. Flecainide restored sinus rhythm in only 2 patients with atrial flutter (20%), in 9 patients with atrial fibrillation (90%), in 12 patients with ventricular tachycardia (80%), and in one of the 2 patients with fasicular tachycardia. Flecainide also successfully terminated the left atrial tachycardia. Two patients experienced proarrhythmic side effects during flecainide administration, one of whom required intervention by cardioversion. Minor dose effects included oral paresthesia, transient drowsiness or dizziness, and occasional visual blurring. Flecainide acetate is an effective antiarrhythmic agent for the acute termination of recent onset paroxysmal atrial and ventricular tachyarrhythmias.     

Medical management of tachycardias (author's transl)]

Guidelines for a step-wise plan of treatment of tachycardias have been compiled based on clinical empirical experience and with the aid of surface electrocardiograms, intracardial electrograms and stimulation techniques. The plan is primarily with the aid of surface electrocardiograms, intracardial electrograms and stimulation techniques. The plan is primarily oriented with respect to the antiarrhythmic efficacy, the adverse reactions and the practicability of the respective agents. Any type of tachycardia, including premature atrial or ventricular contractions, may be regarded as indication for treatment. Treatment is not indicated only in those asymptomatic patients with rare and evanescent tachycardias and in those with less than 300 premature contractions per hour. Beta-adrenergic blockers are the drugs of choice for the persistent sinus tachycardia. Should the latter agents be contraindicated, propafenon, amiodarone or aprindine may be administered. Verapamil and/or digitalis are indicated only for suppression of paroxysmal sinus tachycardias. Atrial premature contractions are best managed with guinidine or disopyramid. An acute reduction of rapid ventricular rates associated with atrial tachycardias, atrial flutter or fibrillation can best be attained through the administration of verapamil prior to digitalis or beta-adrenergic blockers. Re-establishment of sinus rhythm and prophylactic suppression of the latter should be undertaken with quinidine or disopyramid in combination with digitalis and/or either a beta-adrenergic blocker or intravenously-administered verapamil. Verapamil is the drug of choice for initial management of AV-junctional tachycardia for which a combination with digitalis may be considered. An alternative combination is that of a beta-adrenergic blocker and digitalis. For the acute treatment of ventricular tachycardias, lidocain has proved most effective. Although ajmaline and/or propafenon may be given should no response be obtained, electrical cardioversion would be more appropriate. To prevent ventricular tachycardia or when treatment is indicated for ventricular premature beats, ajmaline, propafenon, quinidine, disopyramid or mexiletine, occasionally in combination with a beta-adrenergic blocker should be employed. Verapamil and/or ajmaline, are usually very effective for termination of reciprocal tachycardias. Ajmaline or propafenon in combination with a beta-adrenergic blocker is recommended for the prophylactic treatment of reciprocal tachycardia. In patients who additionally have bradycardia, prolonged QT-intervals or pre-excitation syndromes, the guidelines should be modified accordingly.     

Evaluation and management of ventricular outflow tract tachycardias

Ventricular tachycardia (VT) arising from the right or left ventricular outflow tract (OT) is a recognized arrhythmia in individuals with structurally normal hearts. Treatment options for OTVT include medications, ablation and, rarely, an implantable cardioverter defibrillator (ICD). In the past few years ablation techniques have developed to the point where most OTVTs can be successfully ablated. However, a percentage of cases have remained where ablation is unsuccessful. Some of these cases may represent an epicardial focus of the VT. Several approaches to epicardial VT ablation have been described. We recently described a LVOT-VT variant, which may be epicardial in nature, in a group of patients in whom prior ablation attempts had failed. A trans-aortic ablation approach to outflow tract VT was successful in these patients.     

Electrical management of arrhythmias with emphasis on the tachycardias.

Information from stimulation studies in human beings with tachycardia has resulted in the application of cardiac pacing in the treatment of such patients. Short-term pacing is especially useful in patients with atrial flutter. Long-term pacing with use of chronically implanted units can be applied to patients with different types of supraventricular and ventricular tachycardia. In these patients careful electrophysiologic studies are required before the pacing device is implanted. New developments enabling automatic and more individually designed modes of pacing are urgently needed.     

Evolution and the median- and long-term prognosis of reentry supraventricular tachycardias in children

We have evaluated 37 children with reentrant supraventricular tachycardia and followed them up for 3.9 +/- 2.7 years. Our 37 patients ranged in age from 1 day to 15 years (mean 4.6 +/- 4 years). When supraventricular tachycardia (SVT) began, 14 patients were less than 1 year old (Group A), and 23 were more than 1 year old (Group B). Cardiac heart disease occurred in 6 children, and Wolff-Parkinson-White syndrome was present in 7 children. After the initial episodes of SVT had been converted, chronic therapy was begun in 87% of cases (A 100%, B 78%) and continued for at least 12 months. During follow-up, therapy was discontinued with good results in 51% of patients (A 79%, B 39%). Recurrences were observed in 19% of cases (A 14%, B 22%), and WPW syndrome was a predisposing factor. Among those patients who were treated, none of the drug regimens used, proved significantly better in preventing recurrence. In conclusion: the long-term prognosis of SVT is better in Group A than in B. In Group A it is possible to discontinue therapy in most cases; on the contrary in Group B chronic treatment is often necessary. In this group it is important to evaluate if and how the side effects of the drugs can change the long-term prognosis of these patients.     

Radiofrequency catheter ablation for the treatment of supraventricular tachycardias in children and adolescents

We report our experience in radiofrequency catheter ablation between April, 1992 and December, 1998, in which we treated 287 patients less than 18 years of age (mean 14.3 +/- 3.1 years) with supraventricular tachycardia. Accessory, pathways were the arrhythmic substrate in 252 of the patients (87.8%), the patients having a total of 265 accessory pathways. Atrioventricular nodal re-entry was the cause of tachycardia in 26 patients (9.0%), while atrial flutter was detected in the remaining 9 patients (3.1%). We were able successfully to eliminate the accessory pathway in 236 patients (89%), but 25 patients had recurrent arrhythmias. Ablation proved successful in all cases of atrioventricular node re-entry tachycardia, the slow pathway being ablated in 25 patients, and the fast pathway in only one case. Recurrence of the arrhythmia occurred in three patients (11.5%). We performed a second ablation in these children, all then proving successful. The ablation was successful in all cases of atrial flutter, with one recurrence (11.1%). Overall, therefore, ablation was immediately successful in 271 patients (94.4%), with a recurrence of the arrhythmia in 29 cases (10.7%). The incidence of serious complications was 2.09%. There was one late death due to infective endocarditis, 3 patients suffered complete heart block, 1 had mild mitral regurgitation, and 1 patient developed an haematoma in the groin. We conclude that radiofrequency catheter ablation can now be considered a standard option for the management of paroxysmal supraventricular tachycardias in children and young adults.     

Use of flecainide acetate for refractory junctional tachycardias in children with the Wolff-Parkinson-White syndrome

The response of sustained supraventricular tachycardia to intravenous and oral flecainide acetate was investigated in 5 children, aged 5.5 to 11.5 years, who had tachycardias associated with Wolff-Parkinson-White syndrome. All children had failed to respond to at least 2 conventional agents. The effect of flecainide was studied using intracardiac techniques. Intravenous flecainide terminated tachycardia in all 5 patients. After drug infusion, slow, sustained tachycardia could be initiated in 1 patient. With oral treatment, slow, sustained tachycardia was started in 2 children and nonsustained in 2. One child had no inducible tachycardias. In 4 of 5 patients, long-term treatment has reduced the frequency of episodes and the drug is well tolerated. Thus, flecainide may be used to terminate and suppress junctional tachycardias in children who have failed to respond to conventional therapy.     

Ectopic automatic atrial tachycardia in children: clinical characteristics, management and follow-up

Ectopic automatic atrial tachycardia, an uncommon type of supraventricular tachycardia in children and adults, has been reported to be resistant to medical therapy, and surgical or cryoblation has been recommended. This report describes 10 infants and children (median age 6 months; range birth to 7.5 years) with automatic atrial tachycardia and their management and follow-up. Digoxin alone was unsuccessful in controlling tachycardia in all 10 patients but decreased the tachycardia rate by 5 to 20% in 8. Intravenous (0.1 mg/kg body weight per dose) and oral propranolol successfully suppressed tachycardia in three of five patients and oral propranolol successfully controlled tachycardia in two of five other patients. Class I antiarrhythmic agents--quinidine (three patients), procainamide (four patients) and phenytoin (three patients)--did not control tachycardia in any patients but made the tachycardia rate worse in three patients. Intravenous (5 mg/kg per dose) and oral amiodarone suppressed tachycardia in three of four patients and oral amiodarone suppressed it in another patient. Thus, intravenous propranolol and amiodarone were effective in acutely suppressing automatic ectopic atrial tachycardia and predicted the response to long-term oral therapy. One patient had persistent tachycardia after surgical ablation of the high right atrial ectopic focus, and another patient had unsuccessful catheter ablation of the high right atrial ectopic focus (25 J). During follow-up (10 to 28 months), ectopic atrial tachycardia resolved completely in four patients and was well controlled in four patients.     

Fetal tachycardias: management and outcome of 127 consecutive cases

OBJECTIVE: To review the management and outcome of fetal tachycardia, and to determine the problems encountered with various treatment protocols. STUDY DESIGN: Retrospective analysis. SUBJECTS: 127 consecutive fetuses with a tachycardia presenting between 1980 and 1996 to a single tertiary centre for fetal cardiology. The median gestational age at presentation was 32 weeks (range 18 to 42). RESULTS: 105 fetuses had a supraventricular tachycardia and 22 had atrial flutter. Overall, 52 fetuses were hydropic and 75 non-hydropic. Prenatal control of the tachycardia was achieved in 83% of treated non-hydropic fetuses compared with 66% of the treated hydropic fetuses. Digoxin monotherapy converted most (62%) of the treated non-hydropic fetuses, and 96% survived through the neonatal period. First line drug treatment for hydropic fetuses was more diverse, including digoxin (n = 5), digoxin plus verapamil (n = 14), and flecainide (n = 27). The response rates to these drugs were 20%, 57%, and 59%, respectively, confirming that digoxin monotherapy is a poor choice for the hydropic fetus. Response to flecainide was faster than to the other drugs. Direct fetal treatment was used in four fetuses, of whom two survived. Overall, 73% (n = 38) of the hydropic fetuses survived. Postnatally, 4% of the non-hydropic group had ECG evidence of pre-excitation, compared with 16% of the hydropic group; 57% of non-hydropic fetuses were treated with long term anti-arrhythmics compared with 79% of hydropic fetuses. CONCLUSIONS: Non-hydropic fetuses with tachycardias have a very good prognosis with transplacental treatment. Most arrhythmias associated with fetal hydrops can be controlled with transplacental treatment, but the mortality in this group is 27%. At present, there is no ideal treatment protocol for these fetuses and a large prospective multicentre trial is required to optimise treatment of both hydropic and non-hydropic fetuses.