A new ECG algorithm for the localization of accessory pathways using only the polarity of the QRS complex.

A new algorithm is proposed for localization of accessory atrioventricular pathways by use of a 12-lead electrocardiogram (ECG). The polarity of the QRS complex in leads III, V1, and V2 from 102 patients with Wolff-Parkinson-White syndrome with manifested preexcitation who underwent successful radiofrequency catheter ablation was analyzed. Accessory pathways on the right side of the heart were localized to three regions around the tricuspid annulus, and left-sided pathways were localized to two regions around the mitral valve annulus. In 42 of 46 patients (91%) with left posterolateral accessory pathways, a common characteristic of the ECG was a positive QRS complex in leads III and V1 (sensitivity 91%, specificity 95%). Of 19 patients with left inferior paraseptal or inferior accessory pathways, 16 (84%) had a negative QRS complex in lead III and a positive QRS complex in lead V1 (sensitivity 84%, specificity 98%). All six patients with right anterosuperior paraseptal accessory pathways had a positive QRS complex in lead III but a negative QRS complex in lead V1 (sensitivity 100%, specificity 97%). The 25 patients with right inferior paraseptal or inferior accessory pathways had a negative or isodiphasic QRS complex in leads III and V1, but the QRS complex was positive in lead V2 in 21 (84%) of these patients (sensitivity 84%, specificity 100%). Finally, five of the six patients (83%) with right anterior accessory pathways had a negative QRS complex in leads III, V1, and V2 (sensitivity 83%, specificity 96%). With the algorithm, the localization of accessory pathways was thus identified in 90 of the 102 patients (88%).

[Auricular flutter associated with an interatrial septal aneurysm submitted to radiofrequency ablation]. / Flutter auricular asociado a un aneurisma del septum interatrial, sometido a ablación con radiofrecuencia.

We present the case of a young man who began with type I atrial flutter, he had no response to antiarrhythmic drugs. The echocardiogram showed an atrial septal aneurysm in the region of the fossa ovalis. We performed an electrophysiologic study which showed an atrial flutter with atrial rate of 257 bpm, and 2:1/3:1 AV conduction. The flutter waves were negatives in leads II, III and a VF (type I atrial flutter). An endocardial mapping was obtained in order to localize the area of slow conduction. It was located in the isthmus of atrial tissue bounded by the inferior vena cava and the tricuspid valve annulus in the low posterior septal right atrium. In this area we applied radiofrequency energy in 10 occasions but the arrhythmia was not suppressed. With atrial pacing we achieve a concealed entrainment and then resumption of atrial flutter after cessation of pacing. After another 6 applications of radiofrequency in this same area in sinus rhythm, we paced the atrium without inducing any form of arrhythmia. He was asymptomatic 15 days later, but one month after the ablation, the flutter reappeared, we performed a second successful radiofrequency ablation. In this time he was asymptomatic.

[The DDD pacemaker implanted intravenously]. / El marcapaso DDD por vía transvenosa.

Retrospectively, we studied 66 consecutive patients in whom we implanted an intravenous DDD pacemaker. The indications were: AV block in 52 patients (79%), sick sinus syndrome in 5 patients (7.5%), both AV block and sick sinus syndrome in 4 patients (6%), and other causes in 5 (7.5%). The venous access route was by subclavian punction in 38 cases (57.5%) and by cephalic vein dissection in 28 (42.5%). With a mean follow-up of 16 months, there were complications in 11 patients (17%), in 9 of them, it was necessary a change in pacing mode different to DDD, and was possible to maintain a DDD pacing mode in 2 patients with a minimal reprogramming. The complications were: A) lost of sense and/or atrial capture in 10 patients (3 of them, had also loss of ventricular capture, one had pacemaker-mediated tachycardia, other had diaphragmatic stimulation and other had a severe infection of the pocket), B) atrial fibrillation appeared in another patient. At the implantation time there were significant differences between patients with and without complications on follow-up, the P wave amplitude was 1.86 +/- 0.75 mV in the first group vs. 3.06 +/- 1.52 mV in the latter group, p < 0.005, and the atrial pacing threshold was 1.10 +/- 1.17 microJ in the first group vs. 0.65 +/- 0.66 microJ in the latter group, p < 0.005. We consider that dual chamber stimulation is a well established form of therapy, although, it requires a more laborious implantation and specialized personal for its follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

[A new electrocardiographic algorithm for localizing accessory pathways using only the polarity of the QRS complex]. / Un nuevo algoritmo electrocardiográfico para la localización de las vías accesorias utilizando únicamente la polaridad del complejo QRS.

From 250 consecutive patients who underwent radiofrequency ablation of accessory pathways, we studied 102 patients with successful ablation of a single overt accessory pathway. All patients had manifested preexcitation on a baseline 12 lead electrocardiogram. None of this patients had additional congenital or acquired cardiac abnormalities which could have affected the QRS morphology. A new algorithm for localizing the AP site was developed, based only on the polarity of the QRS complexes in DIII, V1 and V2, without analysis of the delta wave. We could localize the accessory pathway in five sites with 88% of probability of success. This simplify the electrocardiographic analysis of Wolff Parkinson White and improvement the results of radiofrequency ablation.

[Radiofrequency ablation in idiopathic ventricular tachycardia originating in the right ventricle]. / Ablación con radiofrecuencia en una taquicardia ventricular idiopática originada en el ventrículo derecho.

We present the case of a 10-year-old boy, with structurally normal heart who began two years before admission, with sustained monomorphic ventricular tachycardia with heart rate of 280 bpm and LBBB morphology, AQRS + 60 degrees, with pallor and diaphoresis. The tachycardia was treated with xylocain. He was also treated with propaphenone, verapamil, and amiodarona, in spite of these, he continued with this type of arrhythmia 2 or 3 times a month. We performed an electrophysiologic study which showed ventricular tachycardia originated in the right ventricle infundibulum. We took an endomyocardial biopsy, which was normal. He was scheduled for percutaneous catheter ablation of the tachycardia by radiofrequency energy. During the procedure the ventricular tachycardia appeared spontaneously, we mapped the most early ventricular activation and then in sinus rhythm, this site was pace mapped and resulted in similar pattern of clinical ventricular tachycardia. We identified the site of origin of the ventricular tachycardia in the posterior region of the right ventricle infundibulum, delivering radiofrequency, changing to sinus rhythm. Then we paced the apex of the right ventricle without inducing any form of arrhythmia. He is asymptomatic four months later.

[Identification of patients at risk of malignant arrhythmia in the 1st year after myocardial infarction]. / Identificación de los pacientes con riesgo de arritmias malignas en el primer año postinfarto del miocardio.

Two hundred twenty two consecutive patients with acute myocardial infarction were followed for one year. We evaluated the usefulness of late potentials, the spectral analysis, heart rate variability, infarct-related coronary artery, ejection fraction, arrhythmias during Holter monitoring and other clinical variables as risk markers for developing of ventricular arrhythmias and/or sudden death. Twenty four patients (10.8%) had late arrhythmic events: sudden death in 7, sustained ventricular tachycardia in 15 and unexplained syncope in 2. Late potentials had high sensitivity (94%) and negative predictive value (99%), followed by an occluded related-infarct coronary artery (75% sensitivity and 96% negative predictive value). Complex ventricular arrhythmias during Holter monitoring was the test with the highest specificity (92%). A combination of late potentials plus an occluded infarct-related coronary artery or late potentials plus ejection fraction showed 100% sensitivity with 100% negative predictive value. Of the 16 studied variables, 5 had independent and significative value as a predictor of arrhythmic events, these are, according to the relative risk: late potentials (20.2), ejection fraction less than 40% (12.1), complex arrhythmias during Holter monitoring (7.5), the presence of an occluded infarct-related coronary artery (6.4) and anterior myocardial infarction localization (4.5). We consider, that with a combination of simple methods of assessment, we can select a subgroup of survivors of an acute myocardial infarction at high risk of developing ventricular arrhythmias and sudden death, which also identifies patients with low risk for these complications.

[Reconstruction of the normal right ventricle outflow tract in the Ross operation]. / Reconstrucción del tracto de salida normal del ventrículo derecho en la operación de Ross.

Now a day there are many surgical procedures that require intervention on the normal right ventricular outflow tract (RVOT) and its reconstruction. We present the surgical anatomy of the pulmonary root in the normal RVOT and its reconstruction in the Ross operation in 13 patients operated on from February 1992 through February 1994. The surgical excision of the pulmonary valve was done and in order to keep right ventricle-pulmonary artery continuity (RV-PA), autologous pericardium tubes with bovine pericardium valve [done at the Instituto Nacional de Cardiología (INC)], were elaborated during the surgical procedure in all patients. The postoperative period and its clinical status was satisfactory in all cases, without transpulmonary gradient or regurgitation. We conclude that is important to know the surgical anatomy of the pulmonary root in order to avoid irreversible damage. In the other hand, it is worthy to know the different choices to reconstruct RVOT and its postoperative clinical course.

[Intraoperative circulatory collapse due to a coronary spasm following successful coronary revascularization]. / Colapso circulatorio intraoperatorio debido a espasmo coronario después de revascularización coronaria exitosa.

Coronary artery spasm is recognized cause of angina and circulatory collapse during the operative and early postoperative period following cardiopulmonary bypass for coronary artery surgery. We present our experience with hemodynamical collapse during cardiopulmonary bypass weaning, which were refractory to treatment with inotropics such as noradrenaline and adrenalin and vasodilators such as nitroglycerin. The electrocardiographic changes, poor answer to medical treatment following successful cardiopulmonary bypass for coronary artery surgery, good myocardial protection and complete revascularization suggested severe coronary artery spasm. We used sublingual nifedipine, achieving hemodynamical stability and stopping inotropic support and cardiopulmonary bypass. We review the literature about pathophysiologic mechanism and treatment of coronary artery spasm.