Diagnostic electrocardiography in epidemiological studies of Chagas' disease: multicenter evaluation of a standardized method.

An electrocardiographic recording method with an associated reading guide, designed for epidemiological studies on Chagas' disease, was tested to assess its diagnostic reproducibility. Six cardiologists from five countries each read 100 electrocardiographic (ECG) tracings, including 30 from chronic chagasic patients, then reread them after an interval of 6 months. The readings were blind, with the tracings numbered randomly for the first reading and renumbered randomly for the second reading. The physicians, all experienced in interpreting ECGs from chagasic patients, followed printed instructions for reading the tracings. Reproducibility of the readings was evaluated using the kappa (kappa) index for concordance. The results showed a high degree of interobserver concordance with respect to the diagnosis of normal vs. abnormal tracings (kappa = 0.66; SE 0.02). While the interpretations of some categories of ECG abnormalities were highly reproducible, others, especially those having a low prevalence, showed lower levels of concordance. Intraobserver concordance was uniformly higher than interobserver concordance. The findings of this study justify the use by specialists of the recording of readings method proposed for epidemiological studies on Chagas' disease, but warrant caution in the interpretation of some categories of electrocardiographic alterations.

Age-related changes in sympathetic activity: biochemical measurements and target organ responses.

The aim of this study was to evaluate using several parameters the effect of aging on sympathetic nervous system activity. We measured heart rate, skin conductance level and free and total plasma catecholamines in 60 normal subjects aged 20-80 years, divided into three age groups, in basal supine conditions and in response to standing and to hyperventilation. Basal heart rate was similar in all subjects and failed to correlate with age. Skin conductance level decreased with increasing age and correlated negatively and significantly with age. In response to standing and to hyperventilation, heart rate and skin conductance level increased in all groups but the values attained became lower in older subjects. Basal free and total norepinephrine (NE) and total epinephrine (E) correlated positively and significantly with age. In response to standing, free NE determined at the peak heart rate response, increased significantly only in young subjects. In response to hyperventilation free and total NE increased in all subjects. In conclusion, our study supports and extends previous findings that sympathetic nervous system activity is altered in aging. Moreover, these data also show that biochemical measurements of sympathetic nerve activity do not reflect the same alterations as those involving target organ responses.

Superior vena cava occlusion and/or syndrome related to pacemaker leads.

Four cases of pacemaker-related SVC obstruction or syndrome are reported. While two of them lacked any symptom suggestive of SVC obstruction, the other two presented with mild symptoms. None of them received any treatment. One died from a cause unrelated to SVC obstruction, while the others presented no change in their clinical status. A review of the literature suggests that neither thrombotic nor fibrotic obstruction in patients with pacemaker leads is strictly related to the number of abandoned leads, the presence of severed leads, or the time elapsing from pacemaker implant. The diagnosis is clinically made and is confirmed by venography. Only one of the reported deaths is attributable to SVC obstruction. The remaining cases from the literature responded to treatment with heparin, thrombolytic agents, angioplasty, or surgery.

Left posterior hemiblock related to an interventricular septum tumour. First case in the literature.

A 22-year-old man who engaged in intense and regular physical exercise complained of atypical chest pain. The only remarkable abnormality found in the routine clinical work-up was a left posterior hemiblock. The echocardiogram and the magnetic resonance imaging (MRI) study showed a tumour in the posterior and superior aspect of the interventricular septum where the posterior fascicle of the left bundle is located. It was interpreted that the left posterior hemiblock was produced by the tumour.

[An evaluation of transesophageal atrial pacing for studying the use-dependence effect of anti-arrhythmia drugs]. / Evaluación de la sobreestimulación auricular transesofágica para el estudio del efecto uso-dependencia de las drogas antiarrítmicas.

Use-dependent effect is characteristic of certain antiarrhythmic drugs, mainly those included in Group I of Vaughan-Williams classification. There is an increasing interest in the study of this phenomenon in order to correlate it with the potential arrhythmogenic effect of currently used antiarrhythmic drugs. Use-dependent effect produces widening of the QRS ECG complex as the heart rate is increased. Thus, to produce the necessary changes in heart rate to clinically disclose this phenomenon, endocardial stimulation of the right ventricle is usually done both in control condition and under the effect of the tested drug. As this is an invasive method, the amount of information collected on this important aspect of the antiarrhythmic drug effects has been limited. Hence, we decided to confirm whether transesophageal cardiac pacing is a suitable method to produce controlled changes of the heart rate in order to analyse the use-dependent phenomenon. In this study we included 14 patients, 9 women and 5 men aged 47.85 +/- 13.91 years and ejection fraction of 54.64 +/- 7.19%. Transesophageal stimulation was performed up to the Wenckebach point and the previous rate producing 1:1 A-V response was considered. ECG was recorded in an ink-jet three-channel electrocardiograph at 100 mm/sec chart speed and QRS duration was measured. All patients were studied in the basal unsedated state, free of any medication and after the administration of 3.13 +/- 0.74 mg/kg of flecainide during 4.07 +/- 1.4 days. Atrial capture was obtained with pulses of 15 mA and 18 msec. Heart rate attained before treatment was 150 +/- 21.83 bpm and 144.28 +/- 19.88 bpm under the effect of flecainide (p = NS) (Table 1).(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluación de la sobreestimulación auricular transesofágica para el estudio del efecto uso-dependencia de las drogas antiarrítmicas. / [An evaluation of transesophageal atrial pacing for studying the use-dependence effect of anti-arrhythmia drugs]

Use-dependent effect is characteristic of certain antiarrhythmic drugs, mainly those included in Group I of Vaughan-Williams classification. There is an increasing interest in the study of this phenomenon in order to correlate it with the potential arrhythmogenic effect of currently used antiarrhythmic drugs. Use-dependent effect produces widening of the QRS ECG complex as the heart rate is increased. Thus, to produce the necessary changes in heart rate to clinically disclose this phenomenon, endocardial stimulation of the right ventricle is usually done both in control condition and under the effect of the tested drug. As this is an invasive method, the amount of information collected on this important aspect of the antiarrhythmic drug effects has been limited. Hence, we decided to confirm whether transesophageal cardiac pacing is a suitable method to produce controlled changes of the heart rate in order to analyse the use-dependent phenomenon. In this study we included 14 patients, 9 women and 5 men aged 47.85 +/- 13.91 years and ejection fraction of 54.64 +/- 7.19

. Transesophageal stimulation was performed up to the Wenckebach point and the previous rate producing 1:1 A-V response was considered. ECG was recorded in an ink-jet three-channel electrocardiograph at 100 mm/sec chart speed and QRS duration was measured. All patients were studied in the basal unsedated state, free of any medication and after the administration of 3.13 +/- 0.74 mg/kg of flecainide during 4.07 +/- 1.4 days. Atrial capture was obtained with pulses of 15 mA and 18 msec. Heart rate attained before treatment was 150 +/- 21.83 bpm and 144.28 +/- 19.88 bpm under the effect of flecainide (p = NS) (Table 1).(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluación de la sobreestimulación auricular transesofágica para el estudio del efecto uso-dependencia de las drogas antiarrítmicas. / [An evaluation of transesophageal atrial pacing for studying the use-dependence effect of anti-arrhythmia drugs]

Use-dependent effect is characteristic of certain antiarrhythmic drugs, mainly those included in Group I of Vaughan-Williams classification. There is an increasing interest in the study of this phenomenon in order to correlate it with the potential arrhythmogenic effect of currently used antiarrhythmic drugs. Use-dependent effect produces widening of the QRS ECG complex as the heart rate is increased. Thus, to produce the necessary changes in heart rate to clinically disclose this phenomenon, endocardial stimulation of the right ventricle is usually done both in control condition and under the effect of the tested drug. As this is an invasive method, the amount of information collected on this important aspect of the antiarrhythmic drug effects has been limited. Hence, we decided to confirm whether transesophageal cardiac pacing is a suitable method to produce controlled changes of the heart rate in order to analyse the use-dependent phenomenon. In this study we included 14 patients, 9 women and 5 men aged 47.85 +/- 13.91 years and ejection fraction of 54.64 +/- 7.19

. Transesophageal stimulation was performed up to the Wenckebach point and the previous rate producing 1:1 A-V response was considered. ECG was recorded in an ink-jet three-channel electrocardiograph at 100 mm/sec chart speed and QRS duration was measured. All patients were studied in the basal unsedated state, free of any medication and after the administration of 3.13 +/- 0.74 mg/kg of flecainide during 4.07 +/- 1.4 days. Atrial capture was obtained with pulses of 15 mA and 18 msec. Heart rate attained before treatment was 150 +/- 21.83 bpm and 144.28 +/- 19.88 bpm under the effect of flecainide (p = NS) (Table 1).(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of correlation between the coupling interval of ventricular premature beats and the preceding cycle length.

The accepted variation of 80-120 ms in the coupling interval of non-parasystolic ventricular premature beats has been linked to the duration of the preceding cycle length, but a lack of correlation between these factors has often been found. As a result, there is no explanation for variations in the coupling interval of such ventricular premature beats. To analyze the influence of the preceding cycle length on the coupling interval of isolated ventricular premature beats throughout an entire day, 10 otherwise healthy patients with frequent monofocal non-parasystolic isolated ventricular premature beats were studied with Holter recordings. A sample of the electrocardiogram was obtained at the beginning of each quarter of an hour and coupling intervals as well as preceding cycle lengths of ventricular premature beats not belonging to a bigeminy or trigeminy sequence were measured. Preceding cycle lengths changed in a way similar to the prevailing heart rate, with a marked prolongation during sleep. Coupling intervals showed an irregular pattern during the waking period but increased consistently from the first to the last hour of sleep. The average coupling interval during sleep was significantly longer than during waking (439 +/- 74 vs 466 +/- 80, p less than 0.01). In each patient a similar preceding cycle length within a narrow range of 40 ms was searched for during waking as well as during sleep and the corresponding coupling intervals were significantly longer during sleep (446 +/- 80 vs 466 +/- 85, p = 0.009).(ABSTRACT TRUNCATED AT 250 WORDS)

Transarterial permanent pacing of the left ventricle.

Clinical evaluation of a 64-year-old male patient with a permanent pacemaker showed a right bundle branch block in his ECG that led to the suspicion of catheter misplacement. A two-dimensional echocardiogram and bilateral venogram demonstrated that the pacemaker lead was not in the venous system and that its course was from the axillary artery to the left ventricle passing through the aortic valve. Thirty-three days after implant, replacement of the pacemaker lead through the venous system to stimulate the right ventricular endocardium was performed. At 7 month follow-up the patient has had no complication from his previous arterial pacemaker implantation.

Clinical assessment of the right ventricle anterior papillary muscle extrasystoles with Holter recordings.

To assess the short-term behavior of the right ventricle anterior papillary muscle extrasystoles (APME) based on Holter recording and exercise data, 20 subjects (age 31.5 +/- 13.7 years) with otherwise normal electrocardiogram were studied. APME was diagnosed when it resembled LBBB morphology, with downward oriented AQRS in the frontal plane, slurred r wave in lead V1, and an R/S ratio less than 1 in this same lead. Except for palpitations in ten patients, there were no other symptoms related to the arrhythmia. Two Holter recordings, 30 to 330 days apart, were performed and their results compared. In the first Holter recording, the average rate of VPB/minute was 9.9 +/- 2.5 (xg +/- SD). Half of the patients had couplets and five had ventricular tachycardia. In the second Holter recording, the average rate of VPB/minute was 8.7 +/- 3. In eight cases, couplets were recorded, in half of which one or more episodes of ventricular tachycardia were also noted. Six patients showed another VPB morphology distinct from APME. Stress test suppressed VPB in 10/13 patients, couplets in 2/3 and ventricular tachycardia in the only one with this arrhythmia at the start of the test. Repetitive forms vs APME frequency and vs heart rate exhibited an inverse relationship. We conclude that APME is a clinical condition with both high and stable VPB levels, which can be found in subjects with otherwise normal hearts and in the short-term has a spontaneous uncomplicated outcome.

Comparative antiarrhythmic efficacy of verapamil, 17-monochloracetylajmaline, mexiletine and amiodarone in patients with severe chagasic myocarditis: relation with the underlying arrhythmogenic mechanisms.

The antiarrhythmic effects of verapamil, 17-monochloracetylajmaline, mexiletine and amiodarone were compared in 14 patients with chagasic myocarditis. Drugs and placebo were administered orally in the following order: placebo and verapamil, placebo and 17-monochloracetylajmaline, placebo and mexiletine (1 week each) and placebo and amiodarone (4 weeks each). A 24 hour ambulatory electrocardiographic recording was obtained after administration of each placebo and drug. Verapamil had no effect on the number of ventricular premature complexes, ventricular couplets and runs of ventricular tachycardia. 17-Monochloracetylajmaline did not reduce the number of ventricular premature complexes and ventricular couplets but caused a moderate reduction in runs of ventricular tachycardia. Mexiletine failed to significantly reduce ventricular premature complexes but caused a moderate decrease in both ventricular couplets and runs of ventricular tachycardia. Amiodarone was the only one of the four drugs that caused a substantial reduction of ventricular premature complexes (logarithmic mean 97.8%; p less than 0.001), total suppression of runs of ventricular tachycardia in 11 of 11 patients and suppression of ventricular couplets in 8 of 14 patients and a significant reduction in the remaining 6 patients. The much greater efficacy of amiodarone as compared with the two sodium channel modifiers (17-monochloracetylajmaline and mexiletine) and one calcium channel blocker (verapamil) suggests that its potent antiarrhythmic activity is probably related to other peculiar and still undefined electrophysiologic and pharmacologic properties.

Asthma, cardiac arrhythmias, and albuterol aerosol.

Twenty asthmatic patients clinically free of heart disease were studied for the possible arrhythmogenic action of albuterol (salbutamol). Two puffs of either albuterol or placebo were inhaled four times per day on two consecutive days and continuous ECG recordings obtained during each 24-hour period. Sixteen patients had atrial extrasystoles, four with albuterol, one with placebo, and 11 with both drugs. The extrasystoles/hour were 6.55 (23.75 SD) with albuterol and 8.37 (33.82) with placebo, a nonsignificant difference. Ventricular extrasystoles were shown in 11 patients, two with albuterol, two with placebo, and seven during both treatments. The extrasystoles/hour were 2.57 (6.36) and 3.10 (7.61) with albuterol and placebo, respectively. This difference was not significant. These findings suggest that therapeutic doses of albuterol aerosol in asthmatic patients without evidence of heart disease and severe hypoxemia should not be considered a cause of cardiac arrhythmias.

Enfermedad de Chagas en perros experimentalmente infectados con Trypanosoma cruzi / Chagas disease in dogs experimentally infected with trypanosoma cruzi

Perros mestizos, adultos jóvenes, fueron inoculados con una cepa no letal de T. cruzi. El control de la infección se efectuó durante 620 días e incluyó la obtención del perfil parasitológico, la búsqueda sistemática de anticuerpos específicos y la realización de trazados electrocardiográficos. Durante toda la evolución de la infección, tres de los cuatro perros infectados mostraron una parasitemia sostenida, mientras que en el cuarto animal fue esporádica. Anticuerpos específicos contra T. cruzi fueron detectados a títulos significativos en todos los animales, durante los 620 días. Alteraciones electrocardiográficas inespecíficas fueron observadas en tres perros. Los estudios anatomopatológicos evidenciaron una miocarditis crónica multifocal con lesiones inflamatorias activas, sin nidos de amastigotes tisulares. Los hallazgos observados sugieren la posibilidad de progresión de las lesiones a una miocarditis crónica análoga a la humana (AU)

Enfermedad de Chagas en perros experimentalmente infectados con Trypanosoma cruzi / Chagas' disease in dogs experimentally infected with trypanosoma cruzi

Perros mestizos, adultos jóvenes, fueron inoculados con una cepa no letal de T. cruzi. El control de la infección se efectuó durante 620 días e incluyó la obtención del perfil parasitológico, la búsqueda sistemática de anticuerpos específicos y la realización de trazados electrocardiográficos. Durante toda la evolución de la infección, tres de los cuatro perros infectados mostraron una parasitemia sostenida, mientras que en el cuarto animal fue esporádica. Anticuerpos específicos contra T. cruzi fueron detectados a títulos significativos en todos los animales, durante los 620 días. Alteraciones electrocardiográficas inespecíficas fueron observadas en tres perros. Los estudios anatomopatológicos evidenciaron una miocarditis crónica multifocal con lesiones inflamatorias activas, sin nidos de amastigotes tisulares. Los hallazgos observados sugieren la posibilidad de progresión de las lesiones a una miocarditis crónica análoga a la humana

Cell-mediated reactivity against human and Trypanosoma cruzi antigens according to clinical status in Chagas' disease patients.

The presence of cellular reactivity against homologous tissues and subcellular fractions of Trypanosoma cruzi was investigated in Chagas' disease patients (CDP). CDP were grouped in asymptomatic (CDP-1) and with probable (CDP-2) and overt (CDP-3) cardiomyopathy. Healthy and non-Chagasic cardiomyopathic subjects were studied as controls. Lymphoproliferative reactions against heart tissue extracts were detected in 42% of 72 CDP studied, with similar prevalence of positive reactions in all groups, and correlated with reactivity to both liver and kidney homologous tissues (P less than 0.001). These results confirm the existence of cellular immune reactivity against tissues in CDP, and indicate the lack of organ specificity of this reaction as well as the absence of relation with the clinical state of patients. Cellular reactivity to subcellular fractions of T. cruzi showed a definite pattern according to the clinical status of CDP. Although prevalence of T. cruzi stimulation appeared similar in all groups (70% in CDP-1, 82% in CDP-2 and 75% in CDP-3), CDP-3 showed a significantly higher reactivity to flagellar (69%) and cytosol (63%) fractions than CDP-1 (38 and 27%, respectively). These findings suggest a variable modulation of immune response according to the clinical state of T. cruzi infected subjects.