With the popularization of routine electrocardiography and the widespread use of 24-hour ambulatory electrocardiography in recent years, the detection rate and consultation rate of pediatric arrhythmias are increasing, and they have become one of the more common cardiovascular diseases in pediatric clinics. Due to the deepening of clinical cardiac electrophysiology research in pediatrics, many significant breakthroughs have been made in the treatment of pediatric arrhythmias: the application of radiofrequency ablation technology for the treatment of paroxysmal supraventricular tachycardia and idiopathic ventricular tachycardia has achieved better results; electric defibrillation and cardiac pacing technology have also been greatly improved and are increasingly used in clinical practice, but the application of antiarrhythmic drugs is still the most common and first treatment for pediatric arrhythmias. However, the application of antiarrhythmic drugs is still the most common and the first method used to treat pediatric arrhythmias.
The diagnosis of arrhythmias is generally based on a combination of history, physical examination, and other special tests to determine the nature, cause, and mechanism of arrhythmia, and to formulate treatment and prevention guidelines.
Dynamic electrocardiogram
A dynamic electrocardiogram (DCG) is a body surface electrocardiogram that is recorded continuously over a long period of time. The device was first introduced by Holter in 1957 and put into clinical use in 1961, hence the name Holter ECG. Since the 1990s, new recorders and analysis software have been introduced, with small, lightweight magnetic tape recordings suitable for infants and children, and large-capacity random storage for continuous recording for 72 hours or longer. The new computers have a computer learning function that allows for “human-computer dialogue” to correct errors in the computer’s judgment when they are found in the playback images, thus improving the correctness of the analysis of complex and difficult ECGs.
Exercise electrocardiogram
Exercise test in pediatric patients mostly use the activity plate or bicycle motion detector, without this equipment, the use of squatting, running, up and down stairs, jumping in place and other methods. The physiological changes induced by exercise testing are important for the diagnosis of pediatric arrhythmias. Exercise can increase cardiac output, sympathetic excitation and catecholamine secretion, resulting in faster heart rate and increased myocardial oxygen consumption, and exercise can inhibit benign arrhythmias and induce or aggravate pathological arrhythmias. In recent years, our hospital has adopted an active plate exercise test that can be applied to children over 3 years of age, which is convenient, safe, and easily replayable, with a more stable S-T segment baseline than during the bicycle exercise test.
Esophageal atrial pacing
Transesophageal pacing technique is a non-invasive technique for recording left atrial electrograms and body electrograms by placing an electrode catheter in the posterior part of the left atrium of the esophagus for electrophysiological examination and arrhythmia treatment. Since its introduction in the 1950s, this technique has been rapidly developed and promoted in China because it is non-invasive, requires little equipment, is simple and safe, does not require anesthesia, can be repeatedly applied, and can be successfully applied to pediatric patients, including infants and newborns.
Pediatric intracardiac electrophysiological examination
Intracardiac elecTrophysiology studies in pediatric patients started in the early 1970s and has become one of the main methods for the examination of cardiac arrhythmias. In recent years, radiofrequency catheter ablation has developed rapidly, and most tachyarrhythmias can be effectively treated. Severe hemodynamic disorders such as sinus and third-degree AVB need to be treated with pacemakers. Therefore, at present, intracardiac electrophysiological examination is mostly done together with radiofrequency catheter ablation or pacemaker therapy, and is rarely used alone. However, intracardiac electrophysiological examination is still a key method for accurate diagnosis of arrhythmias.
Selection and clinical application of antiarrhythmic drugs
The selection of effective antiarrhythmic drugs is reasonable in order to improve the efficacy and reduce the adverse effects of the drugs. It is important to be familiar with the pharmacological effects and pharmacokinetic parameters of the drugs, to understand the indications, adverse effects and drug interactions of each drug, and to carefully assess the clinical situation of the child and provide individualized treatment.
Combination of drugs
Anti-arrhythmic drugs are generally not used in combination with two or more drugs. Inappropriate combinations may aggravate toxic effects, especially proarrhythmic effects. Reasonable combination of drugs can control arrhythmias that are not effective with a single drug, and can reduce the dose to avoid or reduce adverse effects.
Proarrhythmic effects of antiarrhythmic drugs Proarrhythmic effects refer to the emergence of new persistent arrhythmias or worsening of existing arrhythmias caused by antiarrhythmic drugs. Currently, research on the proarrhythmic effects of antiarrhythmic drugs is limited to ventricular arrhythmias, and there are no universally accepted diagnostic criteria.
Drug interactions Anti-arrhythmic drugs and drug interactions are divided into pharmacodynamic and pharmacokinetic aspects, so they may add up to enhance the effectiveness of drugs, or they may cancel each other out, or even have the opposite result of proarrhythmia.
Monitoring and evaluation of arrhythmia drug effects
Drug effects include both therapeutic effects and adverse effects. Drug-induced arrhythmias can be detected during hospital monitoring, especially in children with organic heart disease, and are now commonly monitored by means of surface electrocardiograms, ambulatory electrocardiograms, programmed electrocardiograms, exercise test electrocardiograms and blood concentration measurements. Blood concentration measurement can help to adjust the dose of drugs, but the pharmacokinetic parameters of drugs must be fully understood, and the blood concentration can be used to adjust the medication in combination with the clinical situation, so that the medication can be individualized.
Radiofrequency catheter ablation for tachyarrhythmias
Radiofrequency catheter ablation (RFCA) for the treatment of tachyarrhythmias has been developed and popularized extremely rapidly since its introduction in China in 1991.
Radiofrequency current is a kind of electromagnetic wave. According to the frequency band of electromagnetic waves can be divided into the following categories: alternating current (50~60Hz), audible sound (20~20000Hz), radio frequency (100~1.5KHz), ultrasound (1.5~10MHz), and microwave (1000~3000MHz). The RF current used for intracardiac ablation is generally a continuous non-modulated sine wave of 500KHz with a voltage of 40~60V, which has no stimulating effect on nerves and muscles and does not cause significant discomfort to the patient.