Pre-excitation syndrome in arrhythmia

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The article was professionally consulted by Specialist Doctor II Nguyen Quoc Viet - Department of Medical Examination & Internal Medicine - Vinmec Danang International General Hospital. The doctor has more than 20 years of experience in the examination and treatment of cardiovascular diseases and Cardiovascular Interventions (Including angiography, dilation, stenting of coronary arteries, renal arteries...), placing temporary pacemakers , forever...

1. Learn about the normal electrical system of the heart

The heart is made up of 4 chambers: 2 atria and 2 ventricles. Normally, the heart rate is controlled by the sinus node in the right atrium. The sinus node generates a pulse that produces each heartbeat to help maintain a steady heart rate of 60-80 beats per minute.
The electrical impulse travels from the sinus node through the atria and then down to the atrioventricular node (AV node) this is the only way for signals to travel from the atria to the ventricles. The AV node slows the signal before it reaches the ventricles, thereby filling the ventricles with blood. The sinus node helps to maintain a steady heart rhythm sufficient to perfuse blood throughout the body.

2. What is pre-excitation syndrome?

Pre-excitation syndrome is an electrical impulse that does not pass through the atrioventricular node, which slows down the rhythm, but follows a rapid conduction pathway that bypasses the atria to the ventricles, or from the ventricles to the atria; These rapid impulse conduction pathways are located outside the atrioventricular node such as the Ken bridge, James bundle, Mahain, but are connected to the atrioventricular node by bridging of myocardial fiber bundles leading to clinical manifestations of rapid heart rate.
There are several types of pre-excitation syndrome
Pre-excitation syndrome is divided into 3 types:
Type A: WPW syndrome (Wolff-Parkinson-White syndrome). Type B: hidden WPW syndrome (concealed WPW syndrome). Type C: short PR syndrome: (LGL: Lown-Ganon- Lewin syndrome). 2.1 WPW syndrome WPW syndrome (Wolff-Parkinson-White) is a syndrome characterized by cardiac arrhythmias caused by impulses that do not follow the main pathway but "shortcut" through the accessory pathway so that the impulses This can stimulate the heart to beat in an irregular rhythm, causing arrhythmias. Caused by congenital arrhythmia, 80-90% of WPW syndrome is seen in normal heart, can be seen in people with congenital or acquired heart disease such as: Ebstein disease, mitral valve prolapse, cardiomyopathy hypertrophy ... Clinical manifestations are tachycardia, which can occur at any time. Characteristics of paroxysmal tachycardia, atrial fibrillation, atrial flutter. Tachycardia episodes may recur many times. The patient suddenly feels palpitations, palpitations, chest pain, dizziness, difficulty breathing, fainting, or in severe cases, sudden death. Electrocardiogram of WPW syndrome: short PR (or PQ) < 0.12 s, delta wave, or intense R wave, QRS width ≥ 0.12 s, negative T wave, sometimes rhythm rapid, atrial flutter, atrial fibrillation. Complications of WPW syndrome. If not detected early and treated promptly, it can leave many dangerous complications for patients such as: sudden death, low blood pressure, heart failure due to the heart's inability to pump enough blood, frequent fainting. Treatment Patients can self-treat the tachycardia by pressing the eyeball, massaging the carotid sinus, or performing the Valsalva maneuver. Treatment includes treatment of arrhythmias and curative treatment. The methods are using antiarrhythmic drugs, electric shock if there is ventricular fibrillation. Indications for surgery in some cases by burning the accessory pathways with radio waves. 2.2 Hidden WPW syndrome Hidden WPW syndrome is characterized by a pathological conduction pathway associated with the atrioventricular node that produces a unidirectional blockade loop that only allows impulses to travel backwards from the ventricles to the atria (no impulses to go to the atria). from the atrium to the ventricles). Clinical manifestations: similar to WPW syndrome, except for rapid atrial activity in atrial fibrillation or atrial flutter, rarely syncope, no sudden death. Electrocardiogram: When sinus rhythm is normal, atrial fibrillation or atrial flutter, electrocardiogram fails to diagnose occult WPW syndrome. When tachycardia re-entry due to hidden WPW shows atrial reverse: P wave is negative after QRS complex and falls in ST segment, P'R > RP' segment. Treatment is similar to that of WPW syndrome, with some medications added.

2.3 Short PR syndrome Short PR syndrome refers to a short ECG PR interval, followed by a normal QRS complex (without delta waves) associated with a history of paroxysmal tachycardia. The nature of the short PR and tachycardia is due to the fact that atrial muscle fibers bypass the slow conduction portion above the AV node to the distal portion of the AV node or bundle of His, creating a small re-entry loop located in the lower part of the AV node. atrial muscle of the heart. The clinical presentation resembles WPW syndrome, depending on episodes of tachycardia, tachycardia, and atrial flutter. Rapid atrial fibrillation combined with a rapid ventricular rate response can lead to fatal ventricular fibrillation. Rapid atrial flutter in combination with 1:1 atrioventricular conduction, ventricular tachycardia from 220-300 beats/min will cause syncope, lethargy... Electrocardiographic manifestations: Short PR interval < 0.12 seconds. The QRS complex is normal or wider than normal but without delta waves. In the history there have been erroneously recorded episodes of paroxysmal tachycardia. Treatment includes treatment of arrhythmias and curative treatment. The methods are using antiarrhythmic drugs, electric shock if there is ventricular fibrillation. Indications for surgery in some cases by burning the accessory pathways with radio waves. Vinmec International General Hospital is one of the hospitals that not only ensures professional quality with a team of leading doctors, modern equipment and technology, but also stands out for its examination and consulting services. and comprehensive, professional medical treatment; civilized, polite, safe and sterile medical examination and treatment space.

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