What is wpw ablation

An extremely low percentage of patients with WPW suddenly die from ventricular fibrillation. The mechanism is almost certainly an atrial fibrillation with a high ventricular response, which degenerates into a ventricular fibrillation due to the high ventricular rate.

This is a dramatic event that can also occur in asymptomatic subjects, with an incidence of people per year. The ECG can help locate the accessory pathways AP , while the electrophysiological study and intracavity mapping provide precise data on its position and on the electrophysiological properties of the accessory pathways.

In order to define the exact position of the Kent beam, the AV annulus is mapped in order to find the point with the shortest AV interval during the antegrade conduction on the Kent beam or the shortest AV interval during the ventricular pacing or orthodromic tachycardia.

This type of mapping can be performed using bipolar or unipolar recordings and is based on the principle that the activation of the first chamber ventricular during antegrade, atrial conduction during retrograde conduction allows to locate the insertion of the accessory pathway in the chamber.

Therefore, the scaler catheter must be positioned on the right or left AV ring, in contact with the endocardium, and then moved until the shortest conduction interval is found. The position of the catheter is confirmed by fluoroscopy and the recorded potential, which is composed of two deflections, the atrial and ventricular ones. If the catheter is on the Kent beam, it is easy to record almost fused A and V waves, indicating an extremely short conduction time.

Sometimes it is even possible to record the potential of the Kent beam, seen as a rapid short-term deflection, between A and V, expressing the depolarization of the accessory pathway: the waves A and V and the Kent potential are continuous, and the different components are difficult to separate.

The identification of this continuous electrical activity strongly indicates the presence of an accessory route. The first ventricular activation site during manifest pre-excitation pre-excited sinus rhythm, antidromic AVRT identifies the site of ventricular insertion of the accessory pathway. Target site criteria for ablation during antegrade mapping include: 1 AP potential Kent potential , 2 first local ventricular activation related to the onset of the delta wave pre-delta and 3 fusion of atrial and ventricular electrograms.

The potentials of the accessory path reflect a rapid local activation of the accessory pathway and are acute and high frequency deflections between the atrial and ventricular electrograms that precede the onset of the delta wave. The more the local ventricular electrogram on the ablation catheter precedes the onset of the delta wave, the greater the probability of success.

The first atrial activation site during retrograde conduction on the accessory pathway ventricular pacing, orthodromic AVRT identifies its atrial insertion site. A limitation of the mapping during ventricular pacing is that retrograde conduction on the AV node may interfere with the identification of the first atrial activation site on the accessory pathway in particular, septal accessory pathways.

Potential solutions include stimulation at a higher speed to cause decrease or blockage in the AV node , administration of drugs that slow AV nodal conduction or mapping during orthodromic AVRT where retrograde conduction occurs only on the accessory pathways. The criteria for defining the site for ablation include: 1 potentials on the accessory pathways, 2 the first atrial activation site and 3 fusion of electrograms A and V.

The conduction and refractory relationship of the normal A-V conduction system and the bypass section, as well as the stimulation site, determine both the ability to start the tachyarrhythmia circuit, and, theoretically, the type of tachycardia. The conduction and refractory nature of the accessory pathways in most cases behave like contractile muscle tissue; therefore, the accessory pathways demonstrate rapid conduction and present refractory periods, which tend to shorten with the reduction of the lengths of the stimulation cycle PCL.

WPW syndrome allows to verify the presence of all the requisites for a re-entering rhythm: a two anatomical pathways determining from the functional point of view; b one-way block in one of the paths in this case, in the accessory path or in the nodal A-V path ; c a sufficient slowdown in a part of the circuit to overcome the refractoriness before the circulating impulse; and d the impulse conduction time must exceed the longest effective refractory period of any component in the circuit.

Both the antegrade and retrograde refractory periods of the accessory pathway are the main determinants of: a ability to initiate and sustain circular movement, and b ventricular response to atrial tachyarrhythmias e. AVRT is a re-entrant arrhythmia and is classified into orthodromic and antidromic variants.

During orthodromic tachycardia, the antegrade pathway is the AV-His-Purkinje node system and the retrograde pathway is the accessory pathway. On the contrary, during antidromic tachycardia, the antegrade pathway is the accessory pathway and the retrograde pathway is the normal conduction system. For the onset of tachycardia, a premature atrial complex APC , spontaneous or induced by stimulation, hangs on the accessory pathway and travels along the AV-His-Purkinje node.

The impulse conducted reaches the ventricle and returns to the atrium on the accessory route, which has now recovered its excitability. The impulse then returns to the AV-His-Purkinje system, perpetuating tachycardia.

Orthodromic tachycardia can also be initiated by a premature ventricular complex PVC. Approach to the patient with cardiac arrhythmias. Zimetbaum P. Supraventricular cardiac arrhythmias. Goldman-Cecil Medicine. Reviewed by: Michael A. Editorial team. Causes Normally, electrical signals follow a certain pathway through the heart. Symptoms How often a rapid heart rate occurs varies depending on the person.

A person with this syndrome may have: Chest pain or chest tightness Dizziness Lightheadedness Fainting Palpitations a sensation of feeling your heart beating, usually quickly or irregularly Shortness of breath.

Exams and Tests A physical exam done during a tachycardia episode will show a heart rate faster than beats per minute. Treatment Medicines, particularly antiarrhythmic drugs such as procainamide or amiodarone, may be used to control or prevent a rapid heartbeat. Outlook Prognosis Catheter ablation cures this disorder in most people. Possible Complications Complications may include: Complications of surgery Heart failure Reduced blood pressure caused by rapid heart rate Side effects of medicines The most severe form of a rapid heartbeat is ventricular fibrillation VF , which may rapidly lead to shock or death.

You have this disorder and symptoms get worse or do not improve with treatment. Find a Doctor Request an Appointment. American Heart Association. Supraventricular tachycardia. Mayo Clinic; Genetics Home Reference. Benson DW, et al. Wolff-Parkinson-White syndrome: Lessons learnt and lessons remaining.

Cardiology in the Young. Di Biase L, et al. Treatment of symptomatic arrhythmias associated with the Wolff-Parkinson-White syndrome. Dubin AM. Clinical features and diagnosis of supraventricular tachycardia in children. Riggin EA. Allscripts EPSi. Abstract Purpose of review: Catheter ablation has been proven as very effective and safe therapy for patients with symptomatic Wolff-Parkinson-White WPW syndrome.

Publication types Review.