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Copyright of Archivos de Cardiología de México is the property of Publicidad Permanyer SLU and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Archivos de Cardiología de México is the property of Publicidad Permanyer SLU and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Idiopathic ventricular tachycardia is identified in 10% of the patients presenting with ventricular tachycardia, and they consist of various subtypes that can originate from different areas, including the aortic cusps which represent 0.7% of the total. Electrocardiographically, these ventricular tachycardias display a left bundle branch block pattern and inferior axis, and although rare, should be considered in the differential diagnosis with tachycardias originating from the septal region of the right ventricular outflow tract, which comprise 80% of the idiopathic ventricular tachycardias. Despite the vicinity of the left coronary artery ostium, radiofrequency catheter ablation can be curative in more than 90% of cases with a low risk (< 1% of serious complication). Therefore, it must be considered first-line therapy in patients who have failed or are intolerant to therapy with antiarrhythmic agents. The aim of this article is to describe the first case reported in Mexico of a successful ablation idiopathic ventricular tachycardia from the aortic sinus cusp in a patient with incessant ventricular tachycardia.

Unlabelled: In 1992 the radiofrequency ablation program was started, with very good results in patients with supraventricular tachycardias and normal hearts or minimal structural defects. Nevertheless, the results are not as good for the patients with structural defects, that are actually seen more frequently, those are cases with more complex arrhythmias, are patients with cardiac surgery that show a complex arrhythmogenic substrate or patients previously treated with conventional ablation which tachycardia recurs. In these cases, the electroanatomic Carto system has been very useful., Results: In the last two years, 74 procedures with the Carto system were performed, of which 56 have been supraventricular arrhythmias, improving substantially the success rates, Conclusions: The electroanatomical mapping allows the more accurate identification of the arrhythmogenic substrate, achieving better success rates in recurrent tachycardia after conventional ablation, or in cases with more complex arrhythmogenic substrates.

Objective: To analyze the results of radiofrequency catheter ablation (RFCA) of the pulmonary veins (PV) in patients with paroxysmal atrial fibrillation (PAF)., Material and Methods: We describe 4 patients (38 +/- 12 years, interval 8-52; 11 men) with symptomatic PAF, refractory to antiarrhythmic drugs. Special mapping catheters were used and ablation was performed at the ostium/antrum of those veins with abnormal electrical activity (AEA)., Results: AEA in one or more PV was identified in 13 patients (86%); in one patient AEA was also found in the superior vena cava (6.6%). One procedure was complicated by unstable ventricular tachycardia and was notfinished. Success was accomplished in 10, in 5 after the first ablation, in 4 after the second, and in one after a third procedure. One patient had pericarditis with a small pericardial effusion that did not require intervention., Conclusions: RFCA is a useful and relatively safe procedure for the treatment of PAF and the only one with curative potential. The long-term rate of success (with or without antiarrhythmics) in this series was 71%. These results justify catheter ablation in selected patients with symptomatic PAF unresponsive to medical treatment.

Objective: The aim of this study was shown clinical characteristics and follow-up of patients with atrioventricular reentrant tachycardia (AVRT) who underwent radiofrequency catheter ablation (RCA) therapy., Material and Methods: From April 1992 to December 1995, 413 patients with AVRT underwent RCA therapy., Results: Two hundred thirty four men (57%) and one hundred seventy nine women (43%) aged 31.3 +/- 16.3 years were studied. 437 single accessory pathways were found; 24 had multiple accessory pathways. Ablation therapy was successful in 381 accessory pathways. During follow-up of 7 years, AVRT recurred in 51 patients (13%) and in 80% this occurred within the first 3 months after the procedure. 56 patients underwent a second RCA therapy with success in 35 patients (83.5); two reoccurred (5.7%); 365 accessory pathways (83.5) remained without evidence of preexcitation AVRT., Conclusions: During follow-up, these patients with successful ablation therapy remained without symptoms. In patients who underwent a second RCA therapy, atrioventricular reentrant mechanism was always present.

The surface ECG constitutes an invaluable tool for the differential diagnosis in those cases in which the QRS complex exceeds the normal duration (120 mseg or more) and a heart rate of 100 bpm or more. Most of the arrhythmias with wide QRS complexes are ventricular in origin, and frequently related to heart disease; nevertheless, in those patients with hemodynamic stability it is frequently misdiagnosed as supraventricular tachycardia. The importance of the surface ECG resides in the fact that the correct diagnosis can be done with high probability when the analysis is orderly made. To be able to perform such an analysis it is necessary to count upon a good quality ECG, besides it is very important if, in addition, a transesophageal record is available to establish the precise relation between the "p" wave and the ventricular activation. There are the traditional morphologic criteria, with their limited usefulness, but the observations of Brugada et al. increased the sensitivity, which can reach up to 98% with a high degree of specificity (96%). The clinical data plus an adequate ECG analysis can lead to the differential diagnosis with a high grade of certainty.

Atrioventricular nodal reentrant tachycardia is the most frequent regular supraventricular tachycardia. It is generally a benign arrhythmia and usually it is no associated with heart disease. It is more often seen in middle-aged women but it is no infrequent in younger and older patients. The development of radiofrequency with catheter ablation has provided the possibility to definitely cure the arrhythmia and moreover permit a better comprehension of the underlying electrophysiologic and anatomic substrate.

Hypertrophic cardiomyopathy is a relatively common genetic disorder with heterogeneity in mutations, forms of presentation, prognosis and treatment strategies. Hypertrophic cardiomyopathy is recognized as the most common cause of sudden cardiac death that occurs in young people, including athletes. The clinical diagnosis is complemented with the ecocardiographic study, in which an abnormal myocardial hypertrophy of the septum can be observed in the absence of a cardiac or systemic disease (arterial systemic hypertension, aortic stenosis). The annual sudden mortality rate is 1% and, in selected populations, it ranges between 3 and 6%. The therapeutic strategies depend on the different subsets of patients according to the morbidity and mortality, sudden cardiac death, obstructive symptoms, heart failure or atrial fibrillation and stroke. High risk patients for sudden death may effectively be treated with the automatic implantable cardioverter-defibrillator.

We present the case of a 66 years old man with recurrent episodes of syncope, up to three times during the last two months without previous symptoms. An ECG after the syncope showed a bilateral block (left anterior fascicle block and right bundle branch block) and first grade atrioventricular block. The exercise test did not demonstrate either AV conduction disorders or tachyarrhythmia episodes. Holter monitoring showed premature ventricular complexes; tilt testing and carotid sinus massage were normal. The electrophysiologic study revealed no alteration in the conduction system. Throughout atrial and ventricular stimulation documented no tachyarrhythmias. However, intravenous administration of 12 mg of adenosine induced complete AV infra-His block with ventricular asystolia of 7.2 sec duration. Adenosine testing can identify patients with syncope due to paroxysmal AV block even when the electrophysiological findings and other conventional tests are not conclusive.

At present, sudden death is considered a major health problem, DeBoer in 1935, recognized the clinical importance of ventricular fibrillation as the cause of sudden cardiac death. Sudden death due to cardiovascular problems has been established as one of the main causes of death in the developed countries and in developing countries as ours, where the deaths caused by cardiovascular diseases represent 15% of the total, exceeding other causes of death. The frequency of sudden death in our country is unknown, but more frequently we hear about cases of patients that have been reanimated for cardiac arrest; in the United States of America the frequency has been estimated between 400,000 at 500,000 per year although, recently, 250,000 at 300,000 events are being mentioned. It is convenient to comment that the causal arrhythmias are diverse and may vary depending on the underlying disease, although, generally, it can be pointed out that 80% of them are due to tachyarrhythmias. It's important to point out that there is a strong relationship between left ventricular dysfunction, the frequency of ventricular arrhythmias, and fatal cardiac events due to cardiac rhythm disturbances. The recommendations for electrophysiological studies are: 1) patients surviving cardiac arrest, occurring without evidence of an acute Q-wave myocardial infarction and 2) patients surviving cardiac arrest occurring more than 48 hours after the acute phase of myocardial infarction in the absence of a recurrent ischemic event.