bubble_chart Overview

Premature beats, also known as premature contractions, refer to ectopic heartbeats that occur earlier than the dominant rhythm. Based on the location of the ectopic pacemaker, they can be classified into sinus, atrial, atrioventricular junctional, and ventricular premature beats. Ventricular premature beats (ventricular presystole, abbreviated as VPBs) are one of the most common clinical arrhythmias, and in most cases, no direct disease cause can be identified. Literature reports indicate that the incidence of VPBs in normal healthy children is approximately 0.17% to 0.44%. They can occur in all age groups, with higher prevalence observed in prepubescent children, school-aged children, and newborns within the first few days of life. Holter electrocardiograms show that the incidence of VPBs in normal healthy children ranges from 10% to 30%. VPBs can also occur in children with congenital or acquired heart diseases, or in those with certain metabolic disorders and drug poisoning diseases.

bubble_chart Diagnosis

(1) Clinical Manifestations Most children show no obvious symptoms and are incidentally discovered during physical examinations. Older children may occasionally experience palpitations or discomfort in the precordial area. Cardiac auscultation may reveal premature beats followed by a longer pause.

(2) Electrocardiogram (ECG) Examination This can confirm the diagnosis. 1. Premature QRS complexes appear without preceding P waves. 2. The premature QRS complexes are abnormal in morphology and widened in duration (>0.08 seconds in infants, >0.10 seconds in children), with the T wave direction opposing the main QRS wave direction. 3. A complete compensatory pause often follows the premature beat.

(3) Other Laboratory Tests For frequent ventricular premature beats (VPBs), including bigeminy, trigeminy, or consecutive beats, the following tests may be necessary: 1. **Holter Monitoring**: Continuous 24-hour ECG recording to detect other coexisting severe arrhythmias. 2. **Exercise Stress Test**: Includes treadmill or bicycle ergometer tests. Changes in VPBs during or after exercise (increase, decrease, or disappearance), as well as the presence of consecutive or multifocal beats, help determine the nature of VPBs. This test is limited to preschool and school-aged children.

(4) Disease Cause Determination Through medical history, physical examination, and laboratory tests, efforts should be made to identify the underlying cause. Possible causes include mitral valve prolapse, hyperkalemia, long QT syndrome, digitalis toxicity, post-tetralogy of Fallot repair, or VPBs associated with third-degree atrioventricular block. The latter may progress to ventricular tachycardia, ventricular fibrillation, or sudden death.

(5) Differentiating Benign from Organic Premature Beats The following points may serve as references: 1. Presence of underlying heart disease suggests organic origin. 2. Occurrence during treatment with certain drugs (e.g., digitalis or antiarrhythmics) often indicates toxicity. 3. Metabolic disorders (e.g., hyperkalemia or long QT syndrome) often suggest organic causes. 4. VPBs in bigeminy, trigeminy, or consecutive pairs/triplets. 5. Multifocal or polymorphic VPBs. 6. Ventricular parasystole. 7. Markedly abnormal QRS morphology with duration >0.14 seconds. 8. Post-premature beat T-wave changes. 9. R-on-T phenomenon. 10. Frequent VPBs. 11. Increased VPBs after exercise. 12. Concurrent ECG evidence of myocardial damage. While these points aid in determining the nature of VPBs, long-term follow-up is often necessary for confirmation. ECG findings alone may be insufficient, but consecutive or multifocal VPBs and the R-on-T phenomenon warrant attention. Asymptomatic children without organic heart disease and VPBs that decrease or disappear after exercise often suggest benign VPBs.

bubble_chart Treatment Measures

﹝Treatment﹞

The treatment of ventricular premature beats depends on their nature, disease cause, symptoms, cardiac function status, and the presence or risk of developing severe arrhythmias. Benign premature beats often have no noticeable symptoms and generally do not require treatment. Clear explanations should be provided to the patient and their family, and long-term follow-up is recommended.

(1) Disease cause treatment: Address the underlying disease cause accordingly. For example, if ventricular premature beats are caused by drug overdose, discontinue the medication immediately. For those caused by digitalis toxicity, stop digitalis use promptly and administer potassium chloride and phenytoin sodium. For rheumatic carditis, adrenal corticosteroids may be used. For ventricular premature beats associated with prolonged Q-T syndrome or mitral valve prolapse, propranolol or atenolol is preferred. Correct the underlying causes promptly for ventricular premature beats due to hypoxemia, metabolic disorders, or electrolyte imbalances.

(2) Use of antiarrhythmic drugs: The first-line drug in pediatrics is propafenone (Class Ic), which significantly inhibits phase 0, markedly slows conduction, and prolongs repolarization (grade I). It has a rapid clinical onset and mild side effects. The oral dose is 5–7 mg/kg per administration, usually starting with a lower dose. For long-term use, the dose is 4–6 mg/kg every 6–8 hours. After stable efficacy is achieved, continue the medication for 3–6 months, then reduce the dose to 2–4 mg/kg per administration. Maintain this dose for a period before discontinuation, with a total treatment duration of 6–12 months. The drug has low tolerance, and repeated use can still yield satisfactory results. Flecainide, also a Class Ic antiarrhythmic, is currently one of the most effective drugs for treating ventricular premature beats. Its half-life is 11–12 hours, with good oral absorption. The dose is 60–100 mg/m² per day, divided into two doses. Maximum effect is achieved after 3 days, after which the dose can be gradually increased by 10% of the original dose, reaching an average daily dose of 150 mg/m². This drug has mild side effects and is rarely problematic in children.