Mechanism of action of antidysrhythmic drugs on ventricular conduction as studied with intramural electrodes.

Using the Dürrer electrode needle to record the intramural electrogram and a standard peripheral electrocardiogram (ECG) lead as reference, the authors studied the action of 9 different drugs in the conduction system of dogs. The authors concluded that diphenylhydantoin and lignocaine would be useful in dysrhythmias related to increased excitability and perhaps increased automatism. Ajmaline and quinidine may be some of some interest in dysrhythmias due to conduction disturbances; and, finally, ajmaline, diphenylhydantoin, di-isopyramide and quinidine may be useful in dysrhythmias due to focal re-entry.

[Sudden cardiac death: its definition and mechanisms]. / Morte súbita cardíaca: definição e mecanismos.

Sudden cardiac death (SD) is reviewed concerning its definition and mechanisms. About the syndrome definition, one concludes that the most suitable way to discriminate arrhythmic death, is to consider both the time since the beginning of the symptoms and the clinical condition before circulatory arrest. During several years the "arrhythmic hypothesis" prevailed to explain SD mechanism. It postulates that, by a fortuitous association, a ventricular ectopic beat activated a re-entry circuit, unchaining the lethal tachycardia. From that hypothesis, a lot of antiarrhythmic clinical trials were conducted in myocardial infarction survivors, recepting that the ventricular ectopic beats suppression would reduce the probability of lethal arrhythmias. Nevertheless no trial confirmed that hypothesis and CAST showed an increase in mortality in patients treated with antiarrhythmic drugs able to suppress ventricular premature beats. From that observation resulted a reinforcement of the "ischemic hypothesis", supported by several arguments. Today we believe that both factors (ischemic and arrhythmic) are important in SD. It was proposed a SD description as a disfunction of a biological system resulting from the interaction between a "pathological structure" and "functional events". The electrogenic component remains central in that model, but is integrated into a structure/function scheme. Under most conditions, the system requires both abnormal structural components (usually chronic) and functional factors (often transient). The structural pathology is most related to old myocardial infarction scars, and the functional factors are ischemia/reperfusion, metabolic alterations (electrolyte imbalance, hypoxemia, acidosis), hemodynamic failure, neurophysiological fluctuations and toxic effects (like proarrhythmia).(ABSTRACT TRUNCATED AT 250 WORDS)

[Role of antiplatelet agents in the treatment of ischemic cardiopathy]. / Lugar dos antiplaquetários na terapêutica da cardiopatia isquémica.

In spite of the important role played by platelets in the thrombotic complications of coronary heart disease, it has been difficult to prove the preventive efficacy of antiplatelet therapy. Nevertheless, the overview of the results of several randomized trials together with the conclusions of some recent studies are strongly suggestive of the usefulness of those drugs, at least in some subsets of ischemic cardiopathy. So, drugs that affect platelets have been shown to reduce mortality and the risk of infarction in patients with unstable angina and probably also after myocardial infarction, and to preserve the patency of aortocoronary grafts. Their role in preventing thrombotic complications following coronary angioplasty is still uncertain. In spite of the results of recent publications it is still premature to recommend antiplatelet therapy in the primary prevention of ischemic heart disease. It is not yet established the more effective agent inside the group and also the more suitable doses.

[Atrial fibrillation: current trends]. / Fibrilhação auricular--tendências actuais.

The author analyses the current relevance of atrial fibrillation (AF), an arrhythmia no longer viewed as a benign situation, being the first arrhythmic cause of hospitalisation. New data related to the conversion of this arrhythmia to sinus rhythm is reviewed, namely internal atrial defibrillation with low energy shocks and the efficacy of new drugs such as ibutilide. The current role of transesophageal echocardiography in permitting a shorter scheme of anticoagulation before the DC shock is also reviewed. About the importance of maintaining sinus rhythm, the author mentions new data from the Framingham Study showing that AF is an independent predictor of mortality. Attention is drawn to the important role of AF duration before cardioversion, since an "electrical remodeling" does occur, quickly reducing the probability of maintaining sinus rhythm. Concerning the limitations of pharmacological therapy, the author mentions the AFFIRM study that, in a few years, will hopefully solve the controversy concerning the best strategy--maintenance of sinus rhythm versus rate control. Also concerning pharmacological therapy, the author mentions two trials suggestive of the efficacy of amiodarone and dofetilide in AF patients with congestive heart failure. Regarding non-pharmacological options, reference is made to recent advances in surgery of AF and to the search for more simplified operative procedures to reduce intervention risks and duration. To overcome the difficulties in reproducing the maze operation with catheter ablation, new alternatives have appeared, such as energy application inside the pulmonary veins, known as the source of most ectopic atrial beats that trigger AF episodes. The author concludes that since AF is a heterogeneous entity, different therapies must exist, but the pharmacological approach will maintain a central role and non pharmacological therapies should be used as an alternative in refractory cases.

[The patient at risk of sudden death:value of drug therapy]. / O doente em risco de morte súbita: valor da terapêutica farmacológica.

The evaluation of antiarrhythmic therapy should be based on its effects on total mortality assessed by controlled trials. The author reviews the large trials on antiarrhythmic drugs, during the past ten years, and concludes with the current importance of such therapy. Trials have been conducted in three kinds of high-risk populations: patients with malignant ventricular arrhythmias, survivors of myocardial infarction and patients with congestive heart failure. The results have been disappointing, showing either an increase in mortality with antiarrhythmic drugs (class I, d-sotalol) or a neutral effect (amiodarone). Trials conducted in patients with malignant arrhythmias have shown that the implantable cardioverter-defibrillator was superior to the best available antiarrhythmic therapy. In other high-risk populations, the only drugs that consistently reduced mortality were betablockers, which might have other mechanisms of action besides the antiarrhythmic effect. Amiodarone, the most potent suppressor of ventricular arrhythmias, is indicated in highly symptomatic patients; dl-sotalol is a good alternative to amiodarone. We may conclude from these large trials that study endpoints must be correctly chosen in order to assess the real value of an antiarrhythmic drug. The study population must have a high risk of sudden death and be within an appropriate time window of maximal risk. Antiarrhythmic trials must proceed, learning the lessons from the old studies, trying to test new drugs or new therapeutic strategies, better selecting study populations and new risk markers superior to those currently available.

[Antiarrhythmic agents: current situation]. / Fármacos antiarrítmicos: ponto da situação.

Cardiac Arrhythmia Suppression Trial (CAST) had a profound impact on the practice of cardiology. This trial showed the importance of placebo controls in judging the effects of therapy and the pitfalls of using surrogate end points for mortality in clinical disorders. The number of new prescriptions of class I drugs fell progressively after CAST; there was a change in antiarrhythmic drug labelling as well as on research and the "suppression hypothesis" was no more valuable as a theoretical support to the antiarrhythmic treatment of prognostical significant ventricular arrhythmias. Several arguments favour generalization of CAST results to the whole class I drugs. So, all those drugs depress cardiac conductivity, which is potentially arrhythmogenic, and the results of several trials and overviews are in consonance with CAST ones. Beta-blockers are the sole drugs that consistently decreased cardiac sudden death after myocardial infarction. An ancillary study from CAST trial suggests that those drugs can have also an anti-proarrhythmic effect, which needs further confirmation. Beta-blockers can join an important place in malignant ventricular arrhythmias therapy, used lonely or specially in association with drugs from other classes. CAST conclusions are probably not applicable to class III drugs, as they do not depress conductivity, acting mainly by prolonging repolarization. So, they are the most promising drugs in post CAST era: some trials seem to confirm the advantages of amiodarone and DL-sotalol in clinical use, and there are several other new class III drugs in development. A few little and medium dimension amiodarone trials showed a decrease in mortality in myocardial infarction survivors and in patients with cardiac insufficiency. We are waiting the results of some large trials to get more definitive conclusions. In malignant ventricular arrhythmias, empiric amiodarone have been superior to electrophysiological guided therapy. Also in malignant ventricular arrhythmias, DL-sotalol was significantly best than six class I drugs in the prevention of new arrhythmias, the therapy being guided by Holter monitoring or electrophysiological studies. We conclude that in the present state of our knowledge, the greatest promise might hold in the area of complex molecules with a diversity of electrophysiological actions, seeming critical the existence of a sympathicolitic effect for an effective protection against sudden death.

[Atrial fibrillation: anticoagulation or antiaggregation. Is there still a controversy?]. / Fibrilhação auricular: anticoagulação ou antiagregação. Ainda há lugar para controvérsia?

Unlike what happened regarding rheumatic atrial fibrillation, there was no consensus until few years ago about the indication for antithrombotic therapy in nonrheumatic atrial fibrillation. Nevertheless, as it was noticed a high prevalence of stroke in this last situation, several clinical trials were accomplished to clarify the role of those drugs. It was reviewed the five initial big trials, which in spite of having different dimensions, endpoints and design, were remarkably consistent in their results, showing in those patients taking varfarine a 60% reduction in ischemic stroke and systemic embolism. Those results were obtained with an acceptable risk of hemorrhage, which was related to anticoagulation intensity. An European trial showed similar results in secondary prevention, in patients with higher risk, all of them with a previous minor stroke. In some of those trials antiplatelet therapy was also evaluated but only one (SPAF I), showed a significant reduction of stroke with aspirin; the reductions of risk was meanwhile much smaller than with varfarine. As there were a high number of patients with indication for anticoagulants one tried to find thromboembolic risk factors, to identify the population potentially more prone to benefit from that therapy. It was possible in SPAF I trial to find some clinical and echocardiographic risk factors. SPAF II trial directly compare aspirine with varfarine, showing the superiority of the last one but also its greater haemorrhagic risk. That study permitted a better understanding of the indications of those two therapies, according to embolic and haemorrhagic risk of each patient.

[In recurrent atrial fibrillation should a sinus rhythm always try to be maintained? No. What are the therapeutic alternatives?]. / Na fibrilhação auricular recorrente, deve a manutenção do ritmo sinusal ser sempre tentada? Não. Que alternativas terapêuticas?

Despite the high incidence of atrial fibrillation, and the morbidity and mortality associated with this arrhythmia, we are still not sure of the best strategy to deal with it. There is little comparative data between the two strategies most often used: cardioversion and prophylactic antiarrhythmics to maintain sinus rhythm; or pharmacological control of ventricular rate and antithrombotic drugs. The first strategy seems to be the most desirable, but there are two arguments against its use in all patients: 1. It is not indicated when the probability of maintaining sinus rhythm during a sufficiently long period of time is poor. This is case of premature recurrence despite several long course atrial fibrillation treatments (more than one year), and the presence of a very large left atrium. 2. It is not indicated when the advantages of maintaining sinus rhythm do not outweigh its pitfalls. These are mainly related to the use of antiarrhythmic drugs, the efficacy of which is not very great and may present a potential risk of lethal pro-arrhythmia or severe collateral effects. The alternative strategy is feasible with the use of less toxic drugs and the high efficacy and safety of anticoagulant therapy for the prevention of thromboembolic events is currently known. Therefore, we are able to achieve a reasonable control of patient symptoms with a low risk of serious incidents. Trials comparing these strategies have not yet been concluded, therefore therapy must be individualised and based on a correct evaluation of foreseeable risks and benefits.

[Portuguese Association of Arrhythmology, Pacing and Electrophysiology (APAPE). National Registry of Interventional Electrophysiology for 1999]. / Associação Portuguesa de Arritmologia, Pacing e Electrofisiologia (APAPE). Registo Nacional de Electrofisiologia de Intervenção para 1999.

Based on data supplied by the centres that execute Interventional Electrophysiology in Portugal, the authors performed a survey of the electrophysiological studies, with or without associated catheter ablation. This report quantifies the experience of all centres, as well as with different classes of ablation techniques. Furthermore, the authors performed a survey of implanted cardiovertor defibrillators, distinguishing their distribution among the different centres. They conclude that the number of centres that practice Interventional Arrhythmias in Portugal is continuously increasing, as well as the number of catheter ablations performed, although these rates have somewhat stabilised in the last year. The number of implanted cardiovertor defibrillators has also grown yearly since 1992, with a 24% increase last year, but is not yet close to the European average of implants per million of inhabitants.

[National registry of non-invasive electrocardiology in 1999]. / Registo Nacional dos recursos em electrocardiologia não-invasiva em 1999.

The Portuguese Association of Arrhythmology. Pacing and Electrophysiology undertook a national registry on resources available in noninvasive laboratories in 1999. Forty-eight hospital centres answered the inquiry. Holter monitoring is an established technique, owned by all cardiology departments in the main hospitals and in 86% of district hospitals. The 40 centres with the technique have a total of 50 analysers and 166 recorders. The number of examinations performed was 14,046 in 1998 and 14,516 in 1999, which shows a remarkable stability. Ninety-three percent of equipments allow ST segment, 38% QT interval and 33% heart rate variability analysis. It is worth nothing the high activity of cardiopneumology technicians in the reading of the exams (94%). Late potential study is less spread. It is only possible in 38% of centers and between 1998 and 1999 the number of exams declined from 592 to 357. Only 12 centers have event recorders, nevertheless the number performed increased from 251 in 1998 to 283 in 1999. Finally, eight centres have tilt test facilities, but we do not have numbers of the examinations that were performed.

[A retrospective study of a population with intermittent atrial fibrillation]. / Estudo retrospectivo de uma população com fibrilhação auricular intermitente.

OBJECTIVE: To analyse a population with intermittent atrial fibrillation, comparing the clinical characteristics of patients with the idiopathic form with those with structural pathology. DESIGN: Intermittent atrial fibrillation retrospective study. SETTING: Arrhythmology outpatients clinic of the cardiac department. PATIENTS AND METHODS: Retrospective study of a population of 59 patients with intermittent atrial fibrillation referred to the arrhythmology outpatients clinic of the cardiac department. Forty patients were male and nineteen female with a mean age of 51 +/- 13 years. Idiopathic atrial fibrillation group with 18 patients was compared with the 41 patients group with identifiable pathology. Atrial fibrillation was recognised by 12 lead ECG and 24 hours ambulatory Holter monitoring. Clinical and echocardiographic parameters were analysed. Complications and the efficacy of anti-arrhythmic therapy were referred. MAIN RESULTS: In the studied population, mean age at the identification of atrial fibrillation was lower in the idiopathic group than in the group with identifiable pathology. It was 36 +/- 12 years in the first group and 45.2 +/- 13 in the second. Left atrium dimension was 38.1 +/- 4 mm in the first group and 42.5 +/- 9 mm in the second (p = 0.04). In the group with mitral valvulopathy, left atrium dimension was 45.5 +/- 11 mm, also significantly different from patients with the idiopathic form (p = 0.012). Statistically significative difference between those groups was not found for left ventricular end-diastolic dimension and shortening fraction. Mean follow-up was 3 years with a range between 7 months and 10 years. Effective therapeutic control was obtained in 35 of 59 patients (59.3%). Six were from the idiopathic group (33.3%) and 29 from the group with identifiable pathology (70.7%). Control was not reached or was only partial in 24 patients (40.7%), belonging 66.7% to the first group and 29.3% to the second (p = 0.016). No embolic phenomenon was documented in the idiopathic not anti-coagulated group. Four embolic complications (9.8%) were observed in the group of identified pathology. Three of then were related with mitral valvulopathy and were submitted to effective anti-coagulation therapy. CONCLUSIONS: Patients with idiopathic intermittent atrial fibrillation are younger, with smaller left atrium dimension (mainly in relation to those with mitral valve disease) but are more resistant to anti-arrhythmic therapy. They have a trend to less thromboembolic complications and anti-coagulation is probably not justified.

[Relationship between ventricular arrhythmia and clinical and echocardiographic parameters in hypertensive patients]. / Relação entre arritmias ventriculares e parâmetros clínicos e ecocardiográficos em doentes hipertensos.

OBJECTIVE: Evaluation in arterial hypertension (HTA) patients, of the relationship between supraventricular and ventricular arrhythmias, stage of hypertension and echocardiographic parameters. DESIGN: Retrospective study based on the files of ambulatory electrocardiography (Holter). SETTING: Arrhythmology Outpatients Clinic from a Cardiac Department. PATIENTS: Adult patients with arterial hypertension, males and females, who underwent ambulatory electrocardiography (Holter) and echocardiography examinations. MATERIAL AND METHODS: Thirty patients, 15 males and females, 54 +/- 12 years old, were studied. Arterial hypertension was stratified in three stages according with the diastolic value. Symptoms, serum potassium, left ventricular hypertrophy (LVH) on the ECG, and echocardiographic parameters such as left ventricular dimensions, shortening fraction, septal wall and posterior wall thickness and left atrium dimensions were analysed. These parameters were correlated with the arrhythmic pattern concerning the number of premature supraventricular contractions and the number and complexity of premature ventricular contractions (PVC), evaluated by ambulatory electrocardiography (Holter). RESULTS: No relation was found between the arrhythmic pattern, stage of hypertension, symptoms and LVH on the ECG. Septal wall thickness was 14 +/- 3 mm in the group of patients with PVC greater than or equal to 10/hour and 12 +/- 3 mm in the population with PVC less than 10/hour (p less than 0.04). The shortening fraction was 27 +/- 8% in the group of repetitive PVC and 34 +/- 7% in the population without (p less than 0.003). A borderline relation was found between repetitive PVC and left atrium and left ventricular diastolic dimensions. CONCLUSIONS: In a population of arterial hypertension (HTA) who performed ambulatory electrocardiography (Holter), the prevalence of frequent or repetitive PVC was low. A positive correlation between frequent PVC and septal wall thickness and an inverse relation between repetitive PVC and LV shortening fraction, was found. These conclusions are according with the literature, relating the ectopic activity with LVH or deterioration of LV function. No relation was found between arrhythmias and stage of hypertension.

[Amiodarone and propafenone: evaluation using serial Holter recordings in patients with ventricular arrhythmia]. / Amiodarona e propafenona: avaliação por registos de Holter seriados em doentes com arritmias ventriculares.

OBJECTIVE: To review the experience of the Arrhythmology Department in evaluating antiarrhythmic therapy for ventricular arrhythmias with serial Holter electrocardiographic recordings (ECG-H). To compare the results obtained with the most used drugs in this Department: amiodarone and propafenone (groups AMIO and PROP). DESIGN: Retrospective study. No statistically significant differences between the two groups were found in respect to age, sex, underlying disease, functional class, left ventricular function and associated therapy. SETTING: Arrythmology Department at a Cardiology Service. PATIENTS: 105 sequential patients with ventricular arrhythmias in a basal ECG-H recording, that were evaluated within 1 year with a new recording on amiodarone or propafenone, without major clinical events or therapeutic changes between the two recordings. INTERVENTIONS (daily oral doses): Amiodarone 200-600 (mean 270) mg or propafenone 300-900 (mean 602) mg. RESULTS: No statistically significant differences were found between the two groups, in either the basal ECG-H or that recorded on therapy. The two drugs were similar in the degree of suppression of ventricular premature complexes per hour (VPCH): equal or superior to 75% in 64.3% of the patients on amiodarone and in 63.9% of those on propafenone. The following reductions on therapy were statistically significant (p less than 0.001 if not specified): VPCH, from 346 +/- 480 to 86 +/- 158 on amiodarone and from 418 +/- 524 to 110 +/- 215 on propafenone; most complex arrhythmia recorded, on both drugs; number of patients with pairs, from 72.1 to 34.9% on amiodarone and from 69.4 to 33.9% on propafenone; number of patients with runs of nonsustained ventricular tachycardia (VT), from 27.9 to 2.3% on amiodarone (p less than 0.01); number of runs of VT per recording, from 3 +/- 5 to 1 on amiodarone (p less than 0.06); and maximum number of complexes per run of VT, from 8 +/- 8 to 4 on amiodarone and from 7 +/- 4 to 5 +/- 1 on propafenone (both with p less than 0.06). CONCLUSIONS: Holter recordings were useful in evaluating antiarrhythmic therapy. The effectiveness of amiodarone and propafenone in treating ventricular arrhythmias was not significantly different. The choice between one of these drugs must rely on their collateral effects profile.

[Non-invasive evaluation of a population with WPW syndrome]. / Avaliação não invasiva de uma população com o síndroma de WPW.

OBJECTIVE: Evaluation of a WPW Syndrome population by non invasive methods; identification of the sudden death risk; results of treatment and patient selection for Electrophysiologic Studies (EPS). DESIGN: Retrospective study. SETTING: Arrhythmology Outpatients Clinic from a Cardiac Department. PATIENTS: Successive patients older than 12 years with a WPW pattern on the ECG and history of paroxysmal tachycardia followed-up for a period of 46 +/- 29 months. MATERIAL AND METHODS: The clinical, ECG, Holter, stress test and echocardiographic data from 32 patients, were analysed. A study evaluating clinical follow up and the results of treatment was done. RESULTS: The group of patients was very symptomatic. The main complaint was a feeling of tachycardia (84.4%). Orthodromic tachycardia was documented in 7 cases and atrial fibrillation with rapid ventricular rate in five. Intermittent delta wave pattern was found in 21 patients, with 11 cases identified by Holter and 4 by stress test. A predominant left accessory pathway was found (47%), but the anteroseptal location was frequent too (25%). The echocardiogram was not useful in any case. Eighty per cent of the patients became asymptomatic with medical treatment. Beta blockers and amiodarone (the last chance) were the most useful drugs. No mortality was found in the study group. EPS was considered for the 5 patients with paroxysmal atrial fibrillation and the 7 cases resistant to medical treatment. CONCLUSIONS: The difficulty to define the risk of a population with WPW Syndrome by non invasive methods was demonstrated. Eighteen one cases were included in a low risk group, due to the intermittent WPW pattern in the ECG. A high risk group was considered for the 5 patients with atrial fibrillation with fast ventricular rate. The risk was not established in 9 cases. Most of the patients became asymptomatic by medical treatment.

[The catheter ablation of tachyarrhythmias. The experience of the Hospital de Santa Cruz]. / Ablação por cateter de taquiarritmias. Experiência do Hospital de Santa Cruz.

BACKGROUND: First results of tachyarrhythmia's direct current (DC) and radiofrequency (RF) catheter ablation in Portugal (St. Cruz Hospital, Carnaxide). POPULATION AND METHODS: Retrospective analysis of the first 20 patients (P) submitted to catheter ablation in our Center: 11 males and 9 females, aging 36 years (SD 14), with drug-refractory symptomatic tachyarrhythmias. DC ablation was used in the first case and RF current in the nineteen subsequent P. RESULTS: Accessory pathway RF ablation: 92% successful rate (12/13 P); AV nodal modification: fast pathway--1 P (DC ablation), slow pathway--3 P (RF ablation) with one case of late clinical recurrence; two successful His bundle ablation (in paroxysmal atrial flutter/fibrillation) one standard right side and other from left ventricle outflow; one successful RF ablation of a verapamil-sensitive ventricular tachycardia. The mean follow-up was 3.5 months (1 to 7 months for RF and 20 months for DC ablation). CONCLUSIONS: Catheter ablation (mainly RF current) is highly effective in tachyarrhythmia's suppression, with 90% global success in our experience without morbidity.

[The ventricular dysrhythmia profile in patients with mitral valve pathology]. / Perfil disrítmico ventricular em doentes com patologia valvular mitral.

OBJECTIVE: To study the relation between ventricular arrhythmias and echocardiographic left ventricular data, in patients with mitral valve pathology. DESIGN: Retrospective study, based on Holter department data on ventricular arrhythmias. POPULATION: We studied 128 patients: 36 were male, 92 were female. Their mean age was 52 +/- 11 years. Three groups were outlined: 54 patients had mitral stenosis (ME), 15 patients had mitral disease (MD) and 59 had associated aortic pathology (MA). METHODS: Patients clinical records were reviewed according to an evaluating protocol. In each Holter recorded the number of premature ventricular contractions per hour (PVC/h), as well as the existence of complex ectopic forms (CF) was considered. Echocardiographic left ventricular data used was: diastolic diameter (DD), systolic diameter (DS) and shortening fraction (SF). Treatment was not significantly different between the three groups, when 24 hour monitoring was performed. RESULTS: We found the average number of PVC/h to be 14 +/- 45 in the ME group, 58 +/- 85 in the MD group and 52 +/- 11 in the MA group. There is significant difference between ME and either DM, or MA. In patients with ME significant relations were found between the occurrence of CF a greater DS (p < 0.01) and a lesser SF (p = 0.02). No significance was found for the occurrence of PVC. In patients diagnosed as DM, the occurrence of PVC/h (> or = 10) was related with greater DD (p = 0.01) or DS (p = 0.04), but there was no relation to SF. Finally in the MA group PVC occurrence was strongly related (p < 0.01) with all the echocardiographic values and thinner relations were found towards SF (p = 0.02 for DD, p = 0.03 for DS and p = 0.05 for SF). CONCLUSIONS: Ventricular arrhythmic occurrence is less frequent in ME. However, in the three groups, there is worsening left ventricular arrhythmic frequency in direct relation to greater ventricular dimensions, or compromised systolic function.

[Unsustained ventricular tachycardia and accelerated idioventricular rhythm--clinical and electrocardiographic features]. / Taquicardia ventricular não mantida e ritmo idioventricular acelerado--contexto clínico e electrocardiográfico.

OBJECTIVE: To compare clinical and electrocardiographic characteristics of Nonsustained Ventricular Tachycardia (NSVT) and Idioventricular Accelerated Rhythm (IVAR). MATERIAL AND METHODS: We studied 155 patients, 113 men and 42 women, with mean age 54 +/- 14 retrospectively, of these, 108 had NSVT and 47 IVAR. The arrhythmias were defined as follows: NSVT-more than 3 ventricular consecutive beats with an heart rate superior to 110 b/m and lasting less than 30 s.; IVAR-3 or more ventricular consecutive beats with an heart rate equal or superior to 50 and lower than 110 b/m, lasting less than 30 s. We evaluated clinical data (symptoms, functional class and anti-arrhythmic therapy), electrocardiographic data (rhythm, changes in conduction and repolarization) and ventricular function (with ECO, Radionuclide Angiography or Ventriculography). In the Holter recording (ECG-H), we analysed the presence of associated ventricular arrhythmias, their electrocardiographic characteristics (number of episodes, number of beats per episode, previous arrhythmia rate, morfology, regularity) and the relations of the arrhythmia with symptoms. RESULTS: Analysis of underlying pathology showed in both groups, the importance of coronary artery disease (44.5% vs 40%) followed by valvular heart disease (24% vs 27.6%) and cardiomyopathy (22.2% vs 17%) respectively to NSVT and IVAR. Only in the NSVT group there were patients without cardiac pathology (3.6%). Comparing with one control group of our department, this distribution was substantially different (p less than 0.0001). All IVAR episodes were assympthomatic compared with 90% of NSVT. Ventricular premature beats were found in all NSVT patients and in 90% of IVAR patients, and were frequent (greater than 10/h) in 79% and 60%, couplets in 84% and 53% respectively (ns). The previous rate of the arrhythmia was 85.3 +/- 20 b/m in NSVT against 68.7 +/- 14 in IVAR (p less than 0.0001). We found left ventricular disfunction in 60% of NSVT patients and in 63.7% in IVAR patients, being serious in 35% and 39% respectively. The follow-up was of 18.5 months (1-72) and posterior evolution showed 14.8% and 17% of deaths with no relation to the arrhythmia, although in NSVT the number of complexes and episodes were related with the ventricular disfunction (p = 0.02 and p = 0.05). CONCLUSION: Both arrhythmias appeared in patients with similar clinical and arrhythmic setting and identified a population with structural cardiopathy, bad function and poor outcome.

[Catheter ablation with radiofrequency energy in 100 patients with Wolff-Parkinson-White syndrome]. / Ablação por cateter com energia de radiofrequência de 100 doentes com síndrome de Wolff-Parkinson-White.

OBJECTIVE: The aim of this paper was to evaluate our results of radiofrequency catheter ablation (RFCA) of accessory pathways in patients with WPW syndrome. STUDY PATIENTS: We studied 100 consecutive patients with WPW syndrome, 52 men and 48 women, mean age 37 +/- 15 years who underwent RFCA. All patients were symptomatic, with documented episodes of supraventricular tachycardia and 9% of patients had underlying cardiac disease. METHODS: The RFCA was performed without antiarrhythmic drugs in the same session of the electrophysiologic diagnosis. The location of the accessory pathway site was obtained by catheter mapping, based on the premature and/or the presence of Kent potentials. According to the location of the accessory pathway, the ablation catheter was introduced either by the femoral vein or artery with mapping of the tricuspid or mitral ring. In the first cases performed energy application was manually controlled and thereafter was temperature guided with an upper temperature limit of 70 degrees C. We considered primary success criteria the disappearance of the delta wave in the surface ECG and the absence of ventricular preexcitation under atrial pacing and after adenosine injection. Clinical success was defined as the absence of clinical recurrence of tachycardia during the follow-up period. RESULTS: The primary success rate achieved was 88%; 91% in the left free wall pathways, 100% in the right free wall and 85% in the septal pathways (antero-septal-83%; right postero-septal-76.5%; left postero-septal-92%). A second ablation procedure was performed in seven of the twelve patients with primary unsuccess obtaining a final success rate of 93% (left free wall-94.5%; septal pathways-91.6%). After a mean follow-up period of 8 +/- 7 months clinical recurrence occurred in 9% (eight patients), five of which are under anti-arrhythmic therapy (62.5%). Clinical success rate at the end of the follow-up period was 88%. CONCLUSIONS: In our experience RFCA has shown to be safe and with a high success rate in patients with symptomatic pre-excitation. In this group of patients it was an effective therapy.

[Holter electrocardiography en pediatric cardiology: preliminary experience]. / Electrocardiografia de Holter em cardiologia pediátrica: experiência inicial.

PURPOSE: Evaluation of the diagnostic value of continuous electrocardiographic recording (Holter monitoring) in Paediatric Cardiology. STUDY DESIGN: Retrospective study based on the data records of the Arrhythmia Department regarding patients with less than 20 years of age with Holter monitoring performed between January 1983 and February 1995 (374 recordings). PATIENTS: 277 patients were studied, 163 were male and 114 female with a mean age of 12 +/- 5 years. Heart organic anomalies were present in 155 patients and 92 patients had previous cardiac surgery with cardiopulmonary bypass. Clinical indications for Holter recording were the evaluation of symptoms related to arrhythmias (38%), documented dysrhythmia (23%), arrhythmia detected on physical examination (18%) and evaluation of risk in patients without symptoms of arrhythmia (17%). METHODS: Holter recordings were performed during 24 hours with two channels (modified V1 and V5). RESULTS: Significant rhythm and conduction disturbances were found in 122 patients. These were ventricular premature complexes > or = 10/hour (27 patients), AV block (25 patients) and supraventricular premature complexes > or = 10/hour (22 patients). Holter recording revealed significant dysrhythmias in 52% of patients with previously documented dysrhythmia, in 43% of patients referred for assessment of risk without symptoms of arrhythmia, provided insight in 48% of requests due to arrhythmia detected on physical examination and 24% of requests for symptoms related to arrhythmias. In 13 patients the results of Holter recording led to therapeutic or diagnostic measures. CONCLUSIONS: Holter recording showed an overall sensitivity of 44% in the detection of significant arrhythmias and led to therapeutic and additional diagnostic measures in 11% of these patients. Holter recording seems to provide important information in the evaluation of arrhythmias in the paediatric age group.

[The Brugada syndrome--a clinical case]. / Síndrome de Brugada--caso clínico.

A case report of a patient with syncope and family history of sudden death is presented. The precordial recordings in the standard 12-lead ECG showed a right bundle-branch block pattern with persistent ST elevation in V1 and V2-V3. After a thorough evaluation, we found no underlying organic cardiomyopathy. The diagnosis of symptomatic Brugada syndrome was made. A cardioverter-defibrillator was implanted.