Clinical assessment of the effect of digital filtering on the detection of ventricular late potentials.

Ventricular late potentials are low-amplitude signals originating from damaged myocardium and detected on the body surface by ECG filtering and averaging. Digital filters present in commercial equipment may interfere with the ability of arrhythmia stratification. We compared 40-Hz BiSpec (BI) and classical 40- to 250-Hz band-pass Butterworth bidirectional (BD) filters in terms of impact on time domain variables and diagnostic properties. In a transverse retrospective age-adjusted case-control study, 221 subjects with sinus rhythm without bundle branch block were divided into three groups after signal-averaged ECG acquisition: GI (N = 40), clinically normal controls, GII (N = 158), subjects with coronary heart disease without sustained monomorphic ventricular tachycardia (SMVT), and GIII (N = 23), subjects with heart disease and documented SMVT. Conventional variables analyzed from vector magnitude data after averaging to 0.3 micro V final noise were obtained by application of each filter to the averaged signal, and evaluated in pairs by numerical comparison and by diagnostic agreement assessment, using conventional and optimized thresholds of normality. Significant differences were found between BI and BD variables in all groups, with diagnostic results showing significant disagreement between both filters [kappa value of 0.61 (P<0.05) for GII and 0.31 for GIII (P = NS)]. Sensitivity for SMVT was lower with BI than with BD (65.2 vs 91.3%, respectively, P<0.05). Filters provided significantly different numerical and diagnostic results and the BI filter showed only limited clinical application to risk stratification of ventricular arrhythmia.

Clinical assessment of the effect of digital filtering on the detection of ventricular late potentials

Ventricular late potentials are low-amplitude signals originating from damaged myocardium and detected on the body surface by ECG filtering and averaging. Digital filters present in commercial equipment may interfere with the ability of arrhythmia stratification. We compared 40-Hz BiSpec (BI) and classical 40- to 250-Hz band-pass Butterworth bidirectional (BD) filters in terms of impact on time domain variables and diagnostic properties. In a transverse retrospective age-adjusted case-control study, 221 subjects with sinus rhythm without bundle branch block were divided into three groups after signal-averaged ECG acquisition: GI (N = 40), clinically normal controls, GII (N = 158), subjects with coronary heart disease without sustained monomorphic ventricular tachycardia (SMVT), and GIII (N = 23), subjects with heart disease and documented SMVT. Conventional variables analyzed from vector magnitude data after averaging to 0.3 æV final noise were obtained by application of each filter to the averaged signal, and evaluated in pairs by numerical comparison and by diagnostic agreement assessment, using conventional and optimized thresholds of normality. Significant differences were found between BI and BD variables in all groups, with diagnostic results showing significant disagreement between both filters [kappa value of 0.61 (P<0.05) for GII and 0.31 for GIII (P = NS)]. Sensitivity for SMVT was lower with BI than with BD (65.2 vs 91.3 percent, respectively, P<0.05). Filters provided significantly different numerical and diagnostic results and the BI filter showed only limited clinical application to risk stratification of ventricular arrhythmia

Atrial activation during sinus rhythm in patients with rheumatic and non-rheumatic paroxysmal atrial fibrillation. Frequency-domain analysis using signal-averaged electrocardiography.

OBJECTIVE: Using P-wave signal-averaged electrocardiography, we assessed the patterns of atrial electrical activation in patients with idiopathic atrial fibrillation as compared with patterns in patients with atrial fibrillation associated with structural heart disease. METHODS: Eighty patients with recurrent paroxysmal atrial fibrillation were divided into 3 groups as follows: group I - 40 patients with atrial fibrillation associated with non-rheumatic heart disease; group II - 25 patients with rheumatic atrial fibrillation; and group III - 15 patients with idiopathic atrial fibrillation. All patients underwent P-wave signal-averaged electrocardiography for frequency-domain analysis using spectrotemporal mapping and statistical techniques for detecting and quantifying intraatrial conduction disturbances. RESULTS: We observed an important fragmentation in atrial electrical conduction in 27% of the patients in group I, 64% of the patients in group II, and 67% of the patients in group III (p=0.003). CONCLUSION: Idiopathic atrial fibrillation has important intraatrial conduction disturbances. These alterations are similar to those observed in individuals with rheumatic atrial fibrillation, suggesting the existence of some degree of structural involvement of the atrial myocardium that cannot be detected with conventional electrocardiography and echocardiography.

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.

[High resolution electrocardiogram in frequency domain. Use of statistical techniques of spectral correlation for identification of patients with sustained monomorphic ventricular tachycardia]. / O eletrocardiograma de alta resolução no domínio da freqüência. Utilização de técnicas estatísticas de correlação espectral para identificação de pacientes com taquicardia ventricular monomórfica sustentada.

PURPOSE: To evaluate the diagnostic accuracy of monomorphic ventricular tachycardia (MVT), in patients with structural heart diseases and episodes of sustained MVT, using the signal-averaged ECG (SAECG) in the time (TD) and the frequency domain (FD) with statistical techniques of spectral correlation. METHODS: Twenty seven patients with at least one episode of sustained MVT, 30 patients with structural heart diseases and no evidence of ventricular arrhythmias and 80 subjects with no evidence of heart disease have been studied. SAECG was performed in all patients with the following parameters: duration of the filtered QRS, RMS 40 and LAS40 in TD and the mean and the standard deviation of both signal energy intersegmentar spectral correlation and energy frequency edge track in FD. RESULTS: The sensitivity(S) and positive predict value (PPV) of the SAECG in TD, in FD and combined analysis of both domains were: S = 59.3%, 63.0%, 81.5% and PPV = 80.0%, 81.0%, 84.6%, respectively. CONCLUSION: The combined analysis of SAECG in TD and in FD improves the diagnostic accuracy in patients with S sustained MVT.

[Evaluation of fragmented potentials in right bundle branch block without structural myocardium abnormalities. Study made by signal-averaged electrocardiogram on time and frequency domain]. / Avaliação de potenciais fragmentados em presença de bloqueio de ramo direito sem alterações estruturais miocárdicas ventriculares. Estudo pelo eletrocardiograma de alta resolução no domínio da freqüência.

PURPOSE: To evaluate if the presence of right bundle branch block (RBBB), without structural myocardial abnormalities (SMA) can generate fragmented potentials (FP) and spectral turbulence on signal-averaged electrocardiogram (SAECG). METHODS: Twelve children with atrial septal defect (ASD) and incomplete right bundle branch block (IRBBB without SMA (group I) were compared to 17 children with post-operative tetralogy of Fallot (TF) with CRBBB, all with SMA, 5 with ventricular premature beats and 2 with sustained ventricular tachycardia (group II). All had SAECG on time (TD) and frequency domain (FD) with 5 variables analysed. RESULTS: All patients of group I had normal variables, in contrast with group II which presented abnormal variables suggesting FP and ST. CONCLUSION: In ASD without SMA, the isolated IRBBB did not generate FP and ST.

O acometimento isquêmico obstrutivo na cardiomiopatia hipertrófica do tipo septal assimétrico com envolvimento da artéria descendente anterior / Obstrutive ischemic involvement of the left anterior descending coronary artery in asymmetrical septal form of hypertrophic cardiomyopathy

OBJETIVO - Avaliar o papel da doença coronária (DAC) com comprometimento da artéria descendente anterior (ADA) na cardiomiopatia hipertrófica (CMH) e sua repercussão na evolução, visto ser controverso o significado da necrose e fibrose do septo interventricular (SIV) nesta cardiomiopatia. MÉTODOS - Entre 158 pacientes com CMH, selecionados 6 (3,79 'por cento') com CMH e DAC com lesão obrigatória de ADA, sendo 4 homens, entre 52 e 70 (x=65,16) anos, 4 com a forma obstrutiva da CMH. O tempo de diagnóstico da CMH foi de 78 a 182 (x=141) meses e da DAC de 1 dia a 106 (x=42) meses. Os pacientes foram acompanhados com avaliaçöes clínicas e exames complementares periódicos. RESULTADOS - A forma de apresentação da DAC foi em 5 com angina instável e um com infarto do miocárdio. A ADA estava comprometida entre 60 a 100 'por cento', sendo em um lesão única e nos 5 restaurantes com lesão em 2 ou mais vasos. Na evolução, 3 foram submetidos a revascularização miocárdica (RM), um associada a miomectomia septal, um a angioplastia e 2 somente a tratamento clínico. No período de observação de 76 a 124 meses após o diagnóstico da DAC, ocorreu um óbito. No fim do estudo observamos redução nos valores médios do SIV de 1,53 para 1,40cm, gradiente de pressão entre o corpo e a via de saída do ventrículo esquerdo (VE) de 56 para 15,75mmHg, com discreto aumento no diâmetro diastólico do VE de 4,55 para 4,85cm e do diâmetro sistólico de 2,83 para 3,13cm, sem alterar a dimensão do átrio esquerdo (4,13cm). CONCLUSÄO - A DAC da ADA é bem tolerada na CMH septal assimétrica, participando do processo fibrótico septal e melhorando o desempenho cardíaco, não representando problema adverso na evolução da CMH

[Is the apical hypertrophic cardiomyopathy seen in one population in Rio de Janeiro city similar to that found in the East?]. / E a cardiomiopatia hipertrófica apical vista em uma amostra na cidade do Rio de Janeiro similar à encontrada no oriente?

PURPOSE: To investigate the differences between clinical aspects and evolution of apical hypertrophic cardiomyopathy (AHCM) seen in Rio de Janeiro and the Oriental form, which was the first described. METHODS: In 156 patients with AHCM diagnosed in our institution, there were 13 (8.34%) with the apical form of the disease, whose clinical settings, diagnostic procedures and evolution were studied. RESULTS: There were 8 males and 5 females, between 19 and 75 years old, all white. Electrocardiogram (EKG) showed giant T waves in precordial leads in 10 (76.92%), echocardiogram (ECHO) demonstrated apical hypertrophy in all, 10 (76.92%) had only in the left ventricle, 2 in right ventricle and one involving both. Cineangiography corroborated ECHO findings. Follow-up ranged from 6 to 294 months (x = 95.4). Two deaths occurred in patients with RV involvement, due to large atria, atrial fibrillation, tricuspid or mitral insufficiency and thromboembolism. Among the survivors, the patient with RV disease has diastolic restriction and the ones with LV involvement, 9 are asymptomatic using either propranolol (8) or amiodarone (1), and one uses no medication. CONCLUSION: A HCM seen in Rio de Janeiro is similar to that found in the Orient (Japan) regarding presentation, diagnosis and evolution; but in 3 patients we have found RV disease, not described in Japan, characterizing a distinct group with a worse evolution.

É a cardiomiopatia hipertrófica apical vista em uma amsotra na cidade do Rio de Janeiro similar à encontrada no oriente? / Is the apical hypertrophic cardiomyopathy seen in one population in Rio de Janeiro city similar to that found in the east?

OBJETIVO - Investigar a existência de diferença na forma de apresentaçäo clínica e evolutica da cardiomiopatia hipertrófica apical (CMHA), vista em uma amostra na cidade do Rio de Janeiro e a observada no oriente, ond foi descrita. MÉTODOS - Entre 156 pacientes com cardiomiopatia hipertrófica diagnosticados em nossa instituiçäo, foram identificados 13 (8,34 por cento) com a forma apical, sendo estudadas as suas manifestaçöes clínicas, os meios de diagnóstico e a sua evoluçäo. RESULTADOS - Eram 8 homens e 5 mulheres, com idades entre 19 a 75 anos, todos da raça branca, a maioria sintomática. O eletrocardiograma revelou ondas T gigantes em precordiais em 10 pacientes (76,92 por cento), o ecocardiograma (ECO), a presença de hipertrofia apical em todos os casos, sendo em 10 (76,92 por cento) restrita a ponta do ventrículo esquerdo (VE), em dois (15,4 por cento) a ponta do ventrículo direito (VD) e, em 1 (7,68 por cento), acometendo ambos os ventrículos. A cineventriculografia confirmou os achados do ECO. A evoluçäo variou de 6 a 264 meses (x=95,4). Ocorreram dois óbitos (15,4 por cento) em pacientes com o comprometimento associado ao VD, devido ao aumento significativo da dimensäo dos átrios, ocorrência de fibrilaçäo atrial, insuficiência valvar mitral e/ou tricúspide e tromboembolismo. Entre os vivos, a paciente com acometimento do VD evoluiu com restriçäo diastólica, e os restantes com lesäo localizada do VE, 9 estäo assintomáticos em uso de propranolol (8) ou amiodarona (1) e um permanece assintomático sem medicaçäo. CONCLUSÄO - A CMHA vista em uma amostra no Rio de Janeiro é similar a encontrada no oriente (Japäo), quanto à apresentacäo, diagnóstico e evoluçäo, porém notamos em 3 pacientes (23,08 por cento) o acometimento da ponta do VD, näo descrito no oriente, mas com péssimo prognóstico evolutivo.

[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.

[Apical hypertrophic cardiomyopathy with right ventricular involvement]. / Cardiomiopatia hipertrófica apical acometendo o ventrículo direito.

We report right ventricular involvement in apical hypertrophic cardiomyopathy (HCMP) in two women and one man, aged from 19 to 44 years-old, who presented different signs from those with left ventricular disease (who have good clinical evolution), with signs and symptoms of severe diastolic restriction, showing great atrial enlargement and two with atrial fibrillation and death due to thromboembolism. The right ventricular involvement in apical HCMP leads to a worst prognosis than isolated left ventricular disease, does not have the typical electrocardiographic changes and presents with ventricular restriction and tricuspid regurgitation.

[Obstructive ischemic involvement of the anterior descending coronary artery in asymmetrical septal form of hypertrophic cardiomyopathy]. / O acometimento isquêmico obstrutivo na cardiomiopatia hipertrófica do tipo septal assimétrico com envolvimento da artéria descendente anterior.

PURPOSE: The significance of necrosis and fibrosis of the interventricular septum in hypertrophic cardiomyopathy (HCM) is controversial. The purpose of this study was then to evaluate the clinical impact of left anterior descending artery (LAD) disease in HCM. METHODS: Among 158 patients presenting with HCM, 6 (3.79%) had LAD disease. Mean age was 65.16 years (52 to 70), 4 were men and 4 had the obstructive form of HCM. All patients were submitted to complete clinical and laboratory evaluation. Mean time of the diagnosis was 141 months (ranging from 78 to 182) for HCM and 42 months (ranging from one day to 106 months) for LAD disease. RESULTS: Five patients had unstable angina and one had myocardial infarction. LAD disease (60 to 100% coronary narrowing) was present in all patients; one patient had single vessel disease and 5 multivessel disease. During follow-up, 3 patients had coronary artery bypass grafting (CABG), one with associated septal myectomy; one was submitted to coronary angioplasty and 2 were submitted to medical treatment. During a follow-up period ranging from 76 to 124 months after LAD disease diagnosis, one patient died. At the end of the study, a reduction of the thickness of the interventricular septum from 1.53 to 1.40 cm was observed and left ventricular outflow pressure gradient decreased from 56 to 16 mmHg. Left ventricular diastolic diameter increased from 4.55 to 4.85 cm and systolic diameter from 2.83 to 3.13 cm. Left atrium diameter was unchanged. CONCLUSION: LAD disease is well tolerated in the asymmetrical form of HCM and may contribute to septal fibrosis, improving cardiac function. It does not represent an adverse factor in the evolution of HCM.

[Influence of atrial fibrillation in the natural history of hypertrophic cardiomyopathy]. / Influência da fibrilação atrial na história natural da cardiomiopatia hipertrófica.

PURPOSE: To evaluate the influence of atrial fibrillation in the natural history of hypertrophic cardiomyopathy. METHODS: Eighty-eight patients under ambulatory treatment were studied. Most of them presented the asymmetric type of hypertrophic cardiomyopathy (87.5%). Group I (77 cases) was formed by patients who had never had atrial fibrillation and group II (11 cases) by those who had this arrhythmia paroxysmal or established. RESULTS: In group I, with ages 48.02 +/- 14.82 years, left atrial dimensions 4.21 +/- 0.66 cm, there was one sudden death; 69 were treated by clinical means and 7 by surgery; no patient developed thromboembolism neither cardiac failure. In group II, with ages 58.02 +/- 11.04 years and left atrial dimension 5.32 +/- 0.45 cm, there were 4 deaths, 4 thromboembolisms and 3 with cardiac failure; all received only clinical treatment, having improved in clinical status in 71.42% after amiodarone therapy. CONCLUSION: Atrial fibrillation was present in 12.5%, mostly in the asymmetric type, and in patients after 5th decade, all of them with enlarged left atrium (> 4.7 cm), with highest morbidity (thromboembolism and cardiac failure) and mortality. Among the survivors, amiodarone therapy improved functional class in 71.42%.

[Hypocalcemia causing heart failure]. / Hipocalcemia causando insuficiência cardíaca.

A 39-year-old female patient with refractory heart failure has been studied. On February, 1982 she was submitted to right lobar thyroidectomy for remotion of the left thyroid lobe. Following the surgery, she had signs of hypocalcemia and the diagnosis of secondary hypoparathyroidism and heart failure had been made. Seven months after she had acute pulmonary edema, cardiomegaly III (cardiothoracic index = 0.58) with predominant left atrial and left ventricular hypertrophy, which were confirmed by echocardiogram (ECO). The ECO also demonstrated low contractility of the left ventricle. The QT interval was increased on the electrocardiogram (QTc = 0.50 s), the calcium was 5.0 mg/dl with calciuria of 28 mg/day; phosphatemia was 4.8 mg/dl and phosphaturia of 214 mg/day. The level of thyroid hormones (T3 and T4) were in the normal ranges despite the TSH was increased in the beginning of the disease. She was first treated with digitalis, diuretic and vasodilator drugs, thyroid hormone and oral calcium. She had progressive hemodynamic improvement when higher doses of calcium were given with D3 vitamin. The most significant result of this treatment was reduction of the heart size that come back to normal. At the present time patient is treated with thyroid hormone, calcium and D3 vitamin only.

[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.

[Acute myocardial infarct in a patient with dextrorotation]. / Infarto agudo do miocárdio em paciente com dextro-rotção.

A 79-year-old woman developed myocardial infarction associated with acute pulmonary edema. The electrocardiogram recorded QRS complex of QS type in V1 with upper ST extending from V3R to V6R. The polarity of the P wave in bipolar leads was positive, so compatible with dextrorotation complicated by myocardial infarction. The dextrorotation was confirmed with chest roentgenogram and echocardiogram.

[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.

[Electrocardiogram in dilated cardiomyopathy]. / O electrocardiograma na cardiomiopatia dilatada.

The authors describe the main electrocardiographic features in 90 cases of dilated cardiomyopathy. The patients were divided into tree groups: in group I were the patients with electrocardiographic signs of left ventricular hypertrophy, in group II the patients with complete left bundle branch block and in group III the cases with right bundle branch block, was held in the group I 64 patients (71%), in the group II 22 (24.6%) and in the group III four case (4.4%). Seventy two cases (80%) showed arrhythmias. Atrial fibrillation was observed in 20 patients (28%), supraventricular tachycardia in two (3%), atrioventricular block, of the 1st and 2nd degree, in eight (11%), ventricular arrhythmias in 63 (87.5%) and supraventricular arrhythmias in 42 (58%). In the 64 patients, with left ventricular hypertrophy, 60 (93.75%) showed very important S waves in, at least two right precordial leads. Fourty four patients (73.3%) had rS pattern in right precordial leads, from V1 to V4, with the R waves in V5 and V6 with normal, low and height amplitude. A first degree left bundle branch block was recorded in 16 cases (25%), a pathologic Q waves in 22 (37.5%), low voltage in limb leads in 24 (37.5%), left atrial enlargement in 36 (56%), right atrial enlargement in two (3%) and atrial fibrillation in 10 (16%). In the 22 patients from the group II six (27%) had left atrial enlargement, two (9%) had right atrial enlargement and six (27%) atrial fibrillation. In the four patients from group III two (50%) had an incomplete right bundle branch block, two (50%) the complete form and all had atrial fibrillation.