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Life - Threatening Arrhythmias
in Accessory Pathways. Impact of
Radiofrequency Catheter Ablation

Arbaiza, Jorge L.; Dorantes, Margarita; Castro, Jesús;
Zayas, Roberto; Quiñones, Miguel Angel;
Bueno, Joaquín; Dorticós, Francisco

Instituto de Cardiología y Cirugía Cardiovascular, La Habana, Cuba

SUMMARY
Introduction: Life - threatening arrhythmias are frequent in accessory pathways patients, with a strong lethal potential in young persons generally with a "healthy" heart. They are important because of diagnostic and therapeutical mistakes and for the curative possibility with radiofrequency catheter ablation.
Objective: To study accessory pathways patients with life - threatening arrhythmias and the impact of radiofrequency catheter ablation on their survival.
Material and Methods: 75 patients (91 life - threatening arrhythmias), from 12 to 69 years old, with structurally healthy heart, except one with Ebstein's disease, without antiarrhythmics, along 48 months. With accessory pathways and registered life - threatening arrhythmias or induced during cardiac stimulation and subsequent radiofrequency catheter ablation.
Results: Atrial fibrillation conducted by the accessory pathway was the most frequent (90,7%), followed by atrial flutter through accessory pathway (12%), antidromic tachycardia (9,3%), two pathways tachycardia (4%), Mahaim's pathways (4%) and atrial tachycardia through accessory pathway (1,3%) (there was a frequent association between them). Syncope (65,3%), sudden death (5,3%), first symptom 50,7%, multiple pathways (12%). Ablation was successful in 81,3% even after failed non - pharmacological treatment (direct current ablation or accessory pathways surgery).
Discussion: Life - threatening arrhythmias are frequent in accessory pathways patients, they are a sudden death electrical cause and could be the onset of the disease in those patients. Diagnostic and therapeutical mistakes are frequent and could cause an arrhythmic disaster. Radiofrequency catheter ablation have a few complications, and it is a very safe and effective method.
Conclusion: Radiofrequency catheter ablation is the first choice in patients with accessory pathways and life - threatening arrhythmias.

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INTRODUTION
   Life - threatening arrhythmias are frequent in accessory pathways patients, with a strong lethal potential in young persons generally with a "healthy" heart. They are important because of diagnostic and therapeutical mistakes and for the curative possibility with radiofrequency catheter ablation.

   Accessory pathways are an excellent field for develop of some different supraventricular arrhythmias, with different importance, in presence of them we adopt some behaviors: no treatment, pharmacological therapy, radiofrequency catheter ablation.

   Is very possible that a diagnostic sub register exist because of intermittent or not evident ventricular preexcitation, or sudden death before diagnosis.

   Several arrhythmias in accessory pathways have a strong lethal potential and we most to be as aggressive as arrhythmia is with the patient. In atrial fibrillation and flutter and atrial tachycardia through accessory pathway, this works as a modulator element of the ventricular frequency and because of its histological constitution (ordinary muscle fibers), it does not work as a filter like atrioventricular node and the majority of impulses could be conduced to the ventricles, with a potential or real danger of this high rate developing hypoxia, electrical instability and even degenerating in a ventricular fibrillation. In antidromic tachycardia (even in common accessory pathways like in Mahaim's pathways), the pathway is a essential link on the circuit and usually developed homodynamic effects because of a zone in ventricle will be precociously depolarized, originating and important disorder in the activation sequence.

   Patients with multiple accessory pathways have most often antidromic tachycardia and paroxistic atrial fibrillation.

   The atrial fibrillation (both clinic and laboratory) is present in more than 50% of accessory pathways carriers, why diminished or even disappeared when accessory pathway is destroyed is still ignorate. With not doubt atrial fibrillation through accessory pathway is the most danger arrhythmia in these patients, is the first cause of death and the best prediction sign of malignity of the accessory pathways.

   The use of some antiarrhythmic drugs that blockade the atrioventricular node conduction (digoxin, verapamile, beta blockers) increase the anterograde conduction through accessory pathway and diminished the anterograde refractory period, that's why their inadequate use increase even more the danger in this life - threatening arrhythmias. For all these things we need a curative treatment, in past accessory pathways surgery and DC current catheter fulguration made his job, from past 14 years until now radiofrequency catheter ablation is the choice because of its high effectivity and very low complications incidence.

OBJECTIVE
   To study accessory pathways patients with life - threatening arrhythmias and the impact of radiofrequency catheter ablation on their survival.

MATERIAL AND METHODS
   75 patients (91 life - threatening arrhythmias), 62 male, 13 female (figure 1), from 12 to 69 years old, with structurally healthy heart, except one with Ebstein's disease, without antiarrhythmics (at least 5 medium lifes or 1 month in case of amiodarone), along 48 months (1996 - 2000). With accessory pathways and registered life - threatening arrhythmias or induced during cardiac stimulation, subsequent radiofrequency catheter ablation, pursuit after ablation of 3 months until finally discharge.

Figure 1

RESULTS
   Atrial fibrillation conducted by the accessory pathway was the most frequent and danger (90,7%), followed by atrial flutter through accessory pathway (12%) (Figure 2), antidromic tachycardia (9,3%), two pathways tachycardia (4%), Mahaim's pathways (4%) and atrial tachycardia through accessory pathway (1,3%) (There was a frequent association between them in same patients). Syncope (65,3%), sudden death (5,3%), first symptom 50,7%, multiple pathways (12%), wrong diagnosis of arrhythmia 56%, use of DC electric shock 17,3%, wrong pharmacological treatment of arrhythmia 70,7%, ablation bigger complications 2,7% (1 arterial thrombosis in right leg and 1 tendinous chordate rupture in mitral valve) No deaths patients. Ablation was successful in 81,3% even after failed non-pharmacological treatment (direct current ablation or accessory pathways surgery).

Figure 2: Atrial fibrillation through accessory pathway and atriventricular node, its suddenly gets into atrial flutter through accessory pathway with 1:1 conduction.

DISCUSSION
   Atrial fibrillation through accessory pathway is the most frequent life - threatening arrhythmia (only exceeded by ortodromic tachycardia, the most frequent arrhythmia in accessory pathways carriers and not considered dangerous because of its clinical and electrophysiological characteristics), some theories like the entry of excitation waves in atrium during an ortodromic tachycardia or anisotropic conduction between accessory pathway-atrium union, pretend to explain this high incidence and its elimination after successfully accessory pathway ablation. Other atrial arrhythmias like atrial flutter and atrial tachycardia though less frequent, could represent danger specially in 1:1 conduction through accessory pathway, in our study flutter is the second one arrhythmia; antidromic tachycardia was saw both in one and in two pathways carriers (figure 3), Mahaim's pathways patients even were a little group (just 3 patients) represented danger because 2 of them have had a common accessory pathway too.

Figure 3: Ortodromic tachycardia with complete left bundle branch, suddenly becames into an antidromic tachycardia through a right pathway in a two ways patient.

   The big number of patients with syncope speaks about hemodynamic effects of these arrhythmias. Recovered patients of a sudden death shows us too the very high lethal potential on these cases without consider the probably sub register when the patient is not recovered and was not suspect the existence of the accessory pathway.

   The fact that a life - threatening arrhythmia represent the onset of the preexcitation syndrome in more than a half of these patients speaks about the difficult that sometimes represent the prognosis of an "asymptomatic" accessory pathway.

   The incorrect management of a life - threatening arrhythmia because of its mistaked diagnosis, the inappropriate use of antiarrhythmics (that blockade the atrioventricular node), or the poor use because of afraid of external electric shock therapy is a main problem in an adequate management of these kind of patients.

   Finally we saw a very low index of complications and a very high level of success of the radiofrequency catheter ablation (even in patients with a previous failed DC current accessory pathway fulguration or accessory pathway surgery.

CONCLUSION
   Radiofrequency catheter ablation is the first choice in patients with accessory pathways and life - threatening arrhythmias.

 

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2nd Virtual Congress of Cardiology

Dr. Florencio Garófalo
Steering Committee
President
Dr. Raúl Bretal
Scientific Committee
President
Dr. Armando Pacher
Technical Committee - CETIFAC
President
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