The frequency analysis of signal-averaged ECG of P wave as predictor of efficacy of class III antiarrhythmic drugs to maintain sinus rhythm in recurrent idiopathic atrial fibrillation.

BACKGROUND: The use of class III antiarrhythmic drugs (ADIII) has been considered a good predictor of sinus rhythm in patients post-cardioversion from atrial fibrillation (AF). Several studies using frequency domain analysis of signal-averaged ECG (FDSAECG) of the P wave were able to identify patients at risk for AF. The aim of this study was to assess the FDSAECG in predicting recurrence of idiopathic persistent AF (IPAF) in patients under ADIII therapy. METHODS: In 33 patients with two or more previous symptomatic episodes of IPAF, despite classes I and II therapy, the FDSAECG of the P wave was performed during sinus rhythm and free-drug state. The parameters were the mean and standard deviation of the frequency intersegmentar spectral correlation and the standard deviation of the signal frequency edge track. During the follow-up of 30 +/- 18 months, all patients received either amiodarone or sotalol. RESULTS: During the follow-up, the patients were divided into two groups: Group I-frequent recurrence (>or= three events/year; 16 patients), and Group II-infrequent recurrence (< three events/year; 17 patients). With appropriate cutoff points for each parameter analyzed, intense fragmented electrical activity defined by the presence of at least two abnormal criteria were observed in 13 of 16 patients group I and in 3 of 17 patients group II (P = 0.0003). Sensitivity, specificity, positive and negative predictive values for frequent recurrence were 81.3, 82.4, 81.3, and 82.4, respectively. CONCLUSIONS: The results suggested that FDSAECG analysis of the P wave accurately predicted patients whose ADIII therapy will be effective in maintaining the sinus rhythm without frequent recurrence of IPAF.

[Depressed electrical atrial activity in hypertrophic and dilated cardiomyopathies. An electrocardiographic, vectorcardiographic and echocardiographic study]. / Atividade elétrica atrial deprimida nas cardiomiopatias hipertrófica e dilatada. Estudo eletro, veto e ecocardiográfico.

PURPOSE: To evaluate the "normal" or low-voltage P wave of the 12-leads conventional electrocardiogram (ECG), in patients with serious electric ventricular disturbances in hypertrophic (HC) and dilated (DC) cardiomyopathies. METHODS: Twenty cases of cardiomyopathies, 11 HC and 9 DC, ages ranging from 23 to 73 (x = 41) years have been studied. The analysis of the P wave was performed with ECG, amplified ECG at 1 mv = 20 mm and speed-paper at 50 mm/sec (ECG2), and the Frank-system vector-cardiogram (VCG). Voltage, delays and shapes of the P wave were evaluated by ECG2 and amplified VCG with gain at 1 mv = 160 mm. All electrical data were correlated with dimension of the left atrium (LA), dimension of left ventricular diastolic diameter (LVDD), dimension of left ventricular systolic diameter (LVSD), interventricular septal thickness (IST), posterior wall thickness ((PWT) and ejection fraction (EF) of the left ventricle of bidimensional echocardiogram (ECHO). RESULTS: Changes in morphologies and delays on the the P wave were best observed only on ECG2 and VCG. The mean voltage of P wave on ECG was 0.1 mv and the mean duration of the P loop on VCG was 133.7 msec in HC and 145.2 msec in DC, with mean terminal delay of 49.2 msec and 46.8 msec, respectively, due to slow atrial depolarization. CONCLUSION: In HC and DC with severe electric ventricular changes, the low-voltage and increased duration of P wave, are attributed to intraatrial-block due to structural changes of the atrial myocardium.

[Familial complete atrioventricular block in patients with hypertrophic cardiomyopathy]. / Bloqueio atrioventricular total familiar em pacientes com cardiomiopatia hipertrófica.

The association of spontaneous complete heart block and hypertrophic cardiomyopathy is rare. We have studied three patients of the same family, two brothers and one nephew, ages 19-41 years, with hypertrophic cardiomyopathy confirmed by hemodynamic and angiographic studies. All patients were treated with permanent cardiac pacemaker implant. They are asymptomatic, aging 33 to 55 years, with follow-up of 157 to 176 months after the onset of the heart block.

[Evaluation of syncope in patients with chronic Chagas heart disease]. / Avaliação da síncope em pacientes com cardiopatia chagásica crônica.

PURPOSE: To evaluate causes of syncope in patients with Chagas' disease and intraventricular conduction disturbances. METHODS: Nine patients have been studied, being seven males. Average of 49 years. The studied consisted of His Bundle electrogram, determination of Wenckebach period (WP), sinus node recovery time (SNRT), atrial stability and programmed ventricular stimulation (PVS). RESULTS: Monomorphic ventricular tachycardia (VT) was induced in five patients (55.5%), WP depression was observed in three cases, H-V interval prolongation occurred in three cases and the SNRT was normal in hall patients. In one case the electrophysiological study was completely normal. Among five patients with induced VT, with a mean follow-up period of seven months, one died suddenly, three became asymptomatic with antiarrhythmic drugs and one went on a non pharmacological therapy. In the other four patients with a mean follow-up period of 21 months, three are asymptomatic and one presents occasional dizziness (patient with a normal study). Among the patients with VT four presented recurrent syncope while in the group of patients without VT (four patients) all had only one syncopal episode. CONCLUSION: Patients with intraventricular disturbances, Chagas' disease and syncope, VT may be responsible for the symptoms in approximately 44% of cases. The PVS must be considered as a routine in the investigation of these patients.

[Significance of prolonged PR interval in patients with His bundle branch block, bifascicular type]. / Significado do intervalo PR prolongado em pacientes com bloqueio dos ramos do feixe de His do tipo bifascicular.

PURPOSE: Evaluation of the prolonged PR interval and its predictive value for trifascicular block in individuals with bifascicular His bundle branch block. PATIENTS AND METHODS: 55 patients, 36 male and 19 female aged 57 + 15.8 years with bifascicular bundle branch block type have been studied. 11 cases had complete left bundle branch block and 44 cases had complete right bundle branch block with left anterior and superior division block. His bundle electrogram and atrial stimulation were performed in all patients. The atrial stimulation rate originating the Wenckebach phenomenon (SP) of the A-V conduction, and the A-H and H-V intervals were compared with the PR interval of the surface electrocardiogram. Patients were divided into three groups according to the PR interval: group I, Pr less than 200 ms, group II, PR between 190-280 ms and group III, PR greater than or equal to 280 ms. RESULTS: There was not linear correlation between the PR interval and WP in the three groups. There was a weak linear ascending correlation between the PR and A-H intervals in groups I and II (r + 0.59 and + + 0.43, respectively) and there was a descending correlation in the group III (r. - 0.64, P less than 0.05). In relation to the H-V interval there was not linear correlation with the PR interval in groups I and II, but there was a good ascending linear correlation in the group III (r 0.84, P less than 0.01). The incidence of prolonged A-H and H-V intervals increased as the PR interval was larger. CONCLUSION: The prolonged PR interval with bifascicular bundle branch block means, in the majority of cases, diffuse damage of the conduction system involving the A-V node and the infranodal region; starting from 280 ms, the delayed PR interval suggests involvement predominantly below the A-V node: to a higher PR interval corresponds a higher H-V interval and also, to a relatively shortest A-H interval.

[Evaluation of the PR intervals in normal and prolonged maximum limit with short QRS]. / Avaliação dos intervalos PR no limite máximo normal e prolongado com QRS estreito.

PURPOSE: Evaluation of the A-V node function by determining the Wenckebach period (WP) and atropine response in cases of normal PR interval, PR interval at maximum normal range and prolonged PR interval, all with short QRS. PATIENTS AND METHODS: 129 patients, 79 male and 50 female, aged 17 to 84 years (mean 59), asymptomatic or with complaints of palpitations, dizziness, presyncope or syncope has been studied. ECG showed supra-ventricular tachycardia, first degree A-V block or intermittent Mobitz I type A-V block and sick sinus syndrome. Preexcitation (WPW) syndrome and longitudinal A-V dissociation were excluded. Electrical transoesophageal atrial stimulation was performed in all patients for evaluating the PR interval and WP. Atropine test was performed in a group of 16 patients. Based on the values of the WP, patients were divided into three groups: group I, WP greater than or equal to 125 ppm (N = 88); group II, WP ranging 125-110 ppm (N = 16) and group III, WP less than or equal to 110 ppm (N = 25). RESULTS: There was a good decreasing lineal correlation between the PR interval and the WP only in the group III (r = 0.76, p less than 0.01). PR interval greater than 240 ms had greatest and significant incidence in the group III in relation to the other groups in which the number of WP post-atropine normalization was observed. CONCLUSION: There is a strong linear decreasing correlation between the PR interval of the ECG and the WP in individuals with WP less than or equal to 110 ppm. PR interval greatest than 0.24 ms corresponds better to WP below 110 ppm (mean 90 ppm) and the majority of these patients do not normalize the WP with the atropine. We suggest the term "first degree A-V block" for those cases with PR interval greater than 240 ms and "A-V depression" for the cases with PR interval shorter than 240 ms when recorded on the surface electrocardiogram and have been normalized with atropine.

[Significance and prognosis of ventricular extrasystole induced by exertion in patients with arterial hypertension with a normal electrocardiogram]. / Significado e prognóstico das extra-sístoles ventriculares induzidas pelo esforço em portadores de hipertensão arterial com electrocardiograma normal.

We studied 13 patients with systemic arterial hypertension and normal electrocardiograms so as to evaluate the significance and prognosis of frequent and complex ventricular premature beats (VPB) induced by exercise testing. After a period of 9 to 33 months of follow-up (mean = 17.6 months), we repeated the exercise testing with the same protocol in all cases. In nine patients (69.2%), the arrhythmia disappeared during exercise, two increased the number of VPB and two others reduced the number of the arrhythmia. Complications, such as sustained ventricular tachycardia, were not seen in any case. The appearance of frequent and complex VPB with stress testing does not seem enhance the risk of sudden death or episodes of spontaneous ventricular tachycardia in patients with arterial hypertension but without electrocardiographic signs of cardiac hypertrophy.