How does the extra path work?
In a healthy heart, an impulse from the atria enters the ventricles only through the atrioventricular node, which delays it for a fraction of a second. With WPW, there is a parallel bundle of muscle fibers that cannot inhibit the impulse. Part of the ventricular myocardium is excited earlier; on the ECG this gives a shortened interval and a characteristic delta wave. The problem arises when the impulse returns along one path and leaves along another, completing the circle: an attack of very frequent regular heartbeats develops at a frequency much higher than usual.
- The extra pathway exists from birth
- ECG shows shortened PQ interval and delta wave
- Circular movement of the impulse causes an attack of tachycardia
- WPW phenomenon - changes without attacks
- WPW syndrome - changes plus attacks
Symptoms of an attack
The attack usually begins suddenly, as if a switch has been flipped, and ends just as suddenly. A person feels a strong, even heartbeat, lack of air, weakness, sometimes lightheadedness and the urge to urinate after an attack. Duration varies from minutes to several hours. In infants, an attack is characterized by restlessness, refusal to eat, paleness and rapid breathing, so it is easy to miss. If an attack is combined with atrial fibrillation, the rhythm becomes very frequent and irregular - this is the most dangerous option, requiring emergency assistance.
- Sudden onset and end of an attack
- Smooth, rapid heartbeat
- Weakness, dizziness, shortness of breath
- Chest discomfort or pressure
- Rarely - fainting
- In children - pallor, lethargy, refusal to feed
Diagnostics
The diagnosis begins with a routine ECG, which shows typical signs of preexcitation. But in some people, the additional pathway conducts the impulse inconsistently, and the film looks normal, so daily monitoring is prescribed. Echocardiography is needed to exclude concomitant congenital heart defects, which are sometimes combined with WPW. The main test for risk assessment and treatment planning is intracardiac electrophysiological study: it determines the location of the pathway and its ability to conduct frequent impulses.
- 12-lead ECG
- Daily ECG monitoring
- Echocardiography to exclude heart defects
- Exercise test
- Electrophysiological study
- Record an ECG during the attack, if possible.
What to do during an attack
At the first attack in your life, you need to call an ambulance: it is important to record an ECG during the heartbeat, this will greatly help in the future. If the attacks are already known to the doctor, he teaches the patient special techniques that increase the tone of the vagus nerve - they are performed in a lying position and only in the ways shown by the doctor. In no case should you take drugs “for palpitations” left from relatives: with WPW, some drugs usually used for tachycardia are dangerous and can speed up the rhythm.
- Stop exertion, sit or lie down
- Perform the techniques taught by the doctor
- Do not take other people's drugs for arrhythmia
- Call 103 in case of fainting, chest pain, prolonged attack
- After an attack, contact a cardiologist with an ECG recording
Treatment and ablation
A radical method is catheter radiofrequency ablation: a thin electrode is placed through the vessel to the heart and the additional path is precisely destroyed. The procedure is performed without an incision in the chest, and the effectiveness of the typical path position is very high; after it, most patients are considered recovered and do not need medications. Ablation is recommended for attacks, as well as for asymptomatic phenomena in people of dangerous professions and athletes. If the variant is asymptomatic, the rest may be observed. Drug therapy is used as a temporary measure and is selected only by a doctor.
- Radiofrequency ablation of the accessory pathway
- Indications: seizures, dangerous profession, high performance sports
- Observation and control of ECG in asymptomatic phenomena
- Selection of drugs only by an arrhythmologist
- Limit caffeine, energy drinks, alcohol
- Risk assessment before admission to competitions
- Follow-up examination after the procedure
