ABSTRACT
The growth of two groups of infants were evaluated, one of them exclusively breast-fed (105 infants) and the other exclusively bottle-fed (61 infants), and compared with one another and with international standards (NCHS). All infants were evaluated by anthropometry at 1, 2, 3, 4, 5 and 6 months of age. A fourth order polynomial was adopted for each infant and for each anthropometric measurement in order to estimate individual growth, and the 5th, 50th and 95th percentiles for weight and length were obtained. For the age of 6 months, the weights of breast-fed boys and girls were always statistically equal to or higher than those of infants fed cow's milk or those of NCHS standards. Breast-fed boys presented significantly longer length than bottle-fed boys but shorter than NCHS standards, and breast-fed girls presented significantly shorter length than both bottle-fed girls and than NCHS standards. The greater weight of exclusively breast-fed infants when compared to NCHS standards at six months of age, which differentiates the present study from several other ones carried out in developing countries, was probably due to the association of the beneficial effects of breast-feeding with those of pediatric follow-up.
Subject(s)
Breast Feeding , Growth/physiology , Body Height , Body Weight , Bottle Feeding , Brazil , Cohort Studies , Female , Follow-Up Studies , Humans , Infant , Infant, Newborn , Male , Poverty , Socioeconomic Factors , Urban PopulationABSTRACT
OBJECTIVE: To evaluate the use of the 10th percentile of weight for age as a cut off point for detection of children under nutritional risk, especially for programs of alimentary supplementation. METHODS: 841 children with age between 10 days and 60 months were studied in a primary health care center located in the periphery of Ribeirão Preto, SP, Brazil. It was a cross-sectional study that included age, sex, weight and height, later computing the z scores of weight for age, height for age and weight for height, on the basis of the data of the NCHS. Through 2x2 type tables, where the results in relation with the 10th percentile (above or below this cut off point) and other indices were compared (above or below - 2 z scores), the capacity of 10th percentile of weight for age to detect children with various anthropometric deficits was estimated. RESULTS: The false negative results were always very low, between 0 and 1%, in opposition to the false positive results, that varied from 76.3 to 90.5%. The values of sensitivity/specificity have been 100/85.9%; 93.3/83.8%; 82.9/85.7%, respectively for deficits of weight for age, weight for height and height for age. CONCLUSIONS: The 10th percentile of weight for age was found adequate for population screening of children with weight for the age and weight for the height deficits (high sensitivity), but these children must be better evaluated later on (too many false positive results). For height for age deficits, the 10th percentile resulted inadequate.
ABSTRACT
This investigation was carried out to compare the clinical course of patients with chronic Chagas' heart disease with that of patients with dilated cardiomyopathy. A total of 125 patients (75 chagasic and 50 nonchagasic) prospectively followed up at the Cardiomyopathy clinic of Santa Casa Hospital from January 1990 to June 1993 entered the study. Patients underwent clinical history, physical examination, serological tests, resting electrocardiogram, chest X-ray and two-dimensional echocardiography. In nonchagasic patients, hypertensive cardiomyopathy was found in 17 of 50 (34%) patients, idiopathic dilated cardiomyopathy in 16 (32%), the association of hypertension and coronary artery disease in 12 (24%) and ischemic cardiomyopathy in two (4%). Twenty-one (23%) chagasic and three (6%) nonchagasic patients died during the study period (P = 0.02). Sudden cardiac death occurred in eight (38%) chagasic patients, pump failure death was detected in 10 (47%) and the mode of death could not be determined in three (14%) patients with chronic Chagas' heart disease. Thus, patients with chronic Chagas' heart disease have a clinical course worse than that of patients with nonchagasic dilated cardiomyopathy. This fact may be ascribed to the electrocardiographic and morphological peculiarities usually found in chronic Chagas' heart disease.
Subject(s)
Cardiomyopathy, Dilated/physiopathology , Chagas Cardiomyopathy/physiopathology , Adult , Aged , Brazil , Cardiomyopathy, Dilated/complications , Chagas Cardiomyopathy/complications , Chronic Disease , Death, Sudden, Cardiac/etiology , Echocardiography , Electrocardiography , Female , Humans , Male , Middle Aged , Prognosis , Prospective Studies , Statistics, NonparametricABSTRACT
OBJECTIVE: To assess the efficacy of partial left ventriculectomy as a treatment for patients with end-stage heart failure. METHODS: From February to June 1995, 7 patients with end-stage heart failure underwent partial left ventriculectomy. Subsequently, patients underwent clinical evaluation every 2 months, and 2-dimensional echocardiography at the 6th and 12th months after cardiac surgery. All patients were given digitalis and diuretics at conventional doses, and captopril or enalapril at maximal tolerated doses. RESULTS: Two (28%) patients died; 1 from cardiac arrhythmia associated with gastrointestinal hemorrhage, and the other suddenly. One (14%) patient developed an embolic cerebrovascular accident. Four (57%) patients were hospitalized for congestive heart failure; all of them had either decreased the daily dose of captopril or enalapril or discontinued the drugs by themselves. Twelve months after ventriculectomy, left ventricular ejection fraction values were greater and left ventricular diastolic dimension and functional class values lower than those found before cardiac operation. CONCLUSION: Beneficial effects of partial left ventriculectomy are observed one year after the surgical procedure. This technique, therefore, can be useful for the treatment of patients with end-stage heart failure.
Subject(s)
Cardiac Surgical Procedures/methods , Heart Failure/surgery , Heart Ventricles/surgery , Angiotensin-Converting Enzyme Inhibitors/therapeutic use , Captopril/therapeutic use , Enalapril/therapeutic use , Follow-Up Studies , Heart Failure/drug therapy , Humans , Terminally IllABSTRACT
INTRODUCTION: Many of the epidemiological studies on the consumption of legal and illegal psychoactive substances have included the evaluation of the influence of social context on the levels of prevalence of this consumption using indirect social indicators such as family income, and educational and housing levels in an attempt to identify individuals or groups in different social contexts. The present study investigates the distribution of consumption of psychoactive substances according to social class in a sample of teenage pupils in Ribeirão Preto, SP, Southeastern Brazil. MATERIAL AND METHOD: A self-applicable questionnaire duly adapted and submitted to a reliability test was applied to a proportional sample of 1,025 teenagers enrolled in the 8th, 9th, 10th and 12th grades in public and private city schools. The questionnaires contained questions about the use of ten classes of psychoactive substances, demographic questions and validation information, as well as questions about the perception and intrinsic behavior related to drug consumption. The adaptation of a model that identifies 5 social class strata (business middle class, managerial middle class, lower middle class, proletariat and subproletariat) on the basis of indicators that situate the individuals within the social relations of production, was used. RESULTS: The 3 middle class strata were more often represented, whereas the proletariat and subproletariat were less frequently represented in this teenage pupil population than in the population in general. There was no difference in alcohol or tobacco consumption according to social class, although prevalence tended to be higher at the two extremes of the social ladder. In contrast, the consumption of illegal substances was higher in the middle class and lower in the proletariat. CONCLUSION: Although the consumption of legal substances did not differ among social classes, the higher consumption of illegal substances by the wealthier teenagers was probably due to the higher cost of these products as compared those of alcohol and tobacco.
Subject(s)
Psychotropic Drugs , Social Class , Substance-Related Disorders/epidemiology , Adolescent , Adult , Alcohol Drinking/epidemiology , Brazil , Cross-Sectional Studies , Humans , Illicit Drugs , Smoking/epidemiology , Surveys and QuestionnairesABSTRACT
INTRODUCTION: Concern over the consumption of psychoactive substances by teenagers has given rise to a great worldwide effort to produce information about this phenomenon. This study set out to investigate the prevalence of consumption of legal and illegal psychoactive substances, its distribution by age, sex and age at first experience of them, among teenage pupils in county, Ribeirão Preto, SP, Southeastern Brazil. MATERIAL AND METHOD: A self-applicable questionnaire duly adapted and submitted to a reliability test was applied to a proportional sample of 1,025 teenagers enrolled in 8th, 9th, 10th and 11th grades at public and private city schools. The questionnaire contained questions about the use of ten classes of psychoactive substances, demographic questions and validation information, as well as questions about the perception and intrinsic behavior related to drug consumption. RESULTS: The sample of 88.9% had consumed alcoholic beverages sometime in their lives, 37.7% had used tobacco, 31.1% solvents, 10.5% medicines, 6.8% marihuana, 2.7% cocaine, 1.6% hallucinogens, and 0.3% of the sample had consumed some opiate substance. The rates of consumption increased with age for all substances; however, the use of tobacco and of illegal substances was less intense during the later years of adolescence. As to sex distribution, boys consumed more than girls, except for medicines, with girls consuming barbiturates, amphetamines and tranquilizers in proportions similar to or higher than those observed among boys. Age at first experience showed that access to psychoactive substances occurred at very early ages. CONCLUSIONS: Experimenting with psychoactive substances, whether legal or illegal, is a frequent phenomenon during adolescence, both among boys and girls, often at very early ages.
Subject(s)
Substance-Related Disorders/epidemiology , Adolescent , Adult , Alcohol Drinking/epidemiology , Brazil , Cross-Sectional Studies , Female , Humans , Male , Prevalence , Psychotropic Drugs , Smoking/epidemiology , Surveys and QuestionnairesABSTRACT
'Carcinoma of the colon does not occur in cases of megacolon' is an axiom held by Brazilian physicians working in endemic areas for Chagas' disease. The objective of the present study was to test this axiom experimentally by submitting rats with experimental megacolon to a carcinogen which causes carcinoma of the colon. Eighty young male Wistar rats received serosal application of either saline (0.9% NaCl) or 2 mM benzalkonium chloride (BAC) to the distal colon. Ten months later randomly chosen saline and BAC rats were injected weekly with dimethylhydrazine (DMH) for 20 weeks. Non-DMH-treated rats from both original groups were maintained, for a total of four experimental groups. Three months after the injections all surviving rats were killed. At autopsy the presence of absence of carcinomas along the colon was recorded. The induction of megacolon was evaluated by morphometry of the wall from the distal colon and myenteric denervation was assessed by neuron counts. An increase of at least 2-fold in distal colon wall thickness confirmed the induction of megacolon in BAC-treated rats. Neuronal counts from BAC and control rats not treated with DMH showed an average denervation of 63%. The number of distal colon carcinomas in BAC+DMH-treated rats was significantly lower than that in DMH-treated rats. These findings appear to contradict the traditional concept of carcinogenesis of the colon. The clinical axiom was reproduced experimentally.
Subject(s)
Chagas Disease/physiopathology , Colonic Neoplasms/physiopathology , Megacolon/physiopathology , 1,2-Dimethylhydrazine , Animals , Benzalkonium Compounds , Carcinogens , Chagas Disease/complications , Colonic Neoplasms/chemically induced , Dimethylhydrazines , Male , Megacolon/etiology , Rats , Rats, WistarABSTRACT
There is evidence in the literature that death following a bee or wasp sting may result from cardiac involvement. This study describes acute cardiac lesions experimentally induced in Wistar Rats submitted to intravenous inoculation of Africanized bee venom (ABV) and killed 1, 4, and 24 h after inoculation. Significant increases in serum enzyme levels were detected; light microscopy showed necrosis of the myocardium; and enzyme histochemistry showed inactivation of enzymes in and around the areas of necrosis. This is the first report of an acute necrotizing cardiac lesion, similar to human myocardial infarction, produced by the inoculation of ABV.
Subject(s)
Bee Venoms/toxicity , Myocardial Infarction/etiology , Animals , Bee Venoms/administration & dosage , Immunodiffusion , Injections, Intravenous , Male , Myocardial Infarction/enzymology , Myocardial Infarction/pathology , Myocardium/enzymology , Myocardium/pathology , Necrosis , Rats , Rats, WistarABSTRACT
The aim of this study was to assess the peripheral and cardiac autonomic system by catecholamine measurements in patients with severe chagasic and nonchagasic heart failure. Fifteen chagasic and 16 nonchagasic patients were enrolled in the study. Plasma venous norepinephrine levels (pg/ml) were 397.26 +/- 250.11 for chagasic and 660.05 +/- 455.57 for nonchagasic patients (p > 0.05), plasma venous epinephrine levels 215.84 +/- 254.04 for chagasic and 106.17 +/- 65.90 for nonchagasic patients (p > 0.05), aortic root norepinephrine levels 435.46 +/- 306.60 for chagasic and 668.16 +/- 512.82 for nonchagasic patients (p > 0.05), aortic root epinephrine levels 300.33 +/- 302.69 for chagasic and 199.98 +/- 162.88 for nonchagasic patients (p > 0.05), coronary sinus norepinephrine levels 636.10 +/- 495.22 for chagasic and 552.17 +/- 535.54 for nonchagasic patients (p > 0.05) and coronary sinus epinephrine levels 226.66 +/- 277.47 for chagasic and 69.21 +/- 35.62 for nonchagasic patients (p = 0.02). Myocardial and peripheral norepinephrine and epinephrine extractions were similar for both groups. Taken together, these findings may suggest that chagasic patients with congestive heart failure have biochemical evidence of cardiac autonomic dysfunction with preservation of the peripheral sympathetic activity.
Subject(s)
Catecholamines/blood , Chagas Cardiomyopathy/blood , Heart Failure/blood , Sinus of Valsalva/metabolism , Adolescent , Adult , Aged , Chagas Cardiomyopathy/complications , Chagas Cardiomyopathy/diagnosis , Child , Echocardiography , Electrocardiography , Female , Heart Failure/diagnosis , Heart Failure/etiology , Humans , Male , Middle Aged , Retrospective StudiesABSTRACT
A hundred-forty-one infants born from 26 to 36 weeks, appropriate-for-gestational-age, were followed from birth until the corrected postmenstrual age of 42 weeks. Weight, height and cephalic perimeter were measured on a weekly basis. Based on the average values and percentiles of these measurements it was adjusted a third degree polynomial function. The growth curves obtained, when compared with the so-called intra-uterine growth curves, showed that during the 40th and 42nd postmenstrual weeks the averages and medians are similar. It was observed that the growth dynamics of the preterm infants showed a catch-up pattern in the immediate postnatal period.
ABSTRACT
The concentration of cardiac tissue noradrenaline (NOR) was determined in Wistar rats injected with 1.5 microliters/100 g body weight Africanized bee venom (ABV) (LD50 = 0.8 microliter/100 g body weight by the intravenous route). The animals were injected with ABV by the intramuscular (IM), intraperitoneal (IP), subcutaneous (SC) and intravenous (IV) routes. Animals injected by the IM, IP and SC routes were sacrificed 4, 7 and 24 hours after injection. The animals injected by the IV route were sacrificed when they became apnoeic (within minutes). NOR levels in animals injected by the IM, IP and SC routes were inconstant and inconclusive. In contrast, animals injected with ABV by the IV route showed a significant decrease in NOR concentration when compared to their respective controls, suggesting tissue NOR release. It is suggested that the mechanism of death of the animals injected IV with ABV seems to be related, at least in part, to functional cardiac alterations secondary to stress-induced NOR release. As a consequence, cardiological monitoring of patients who are victims of multiple bee stings is recommended, together with a judicious evaluation of therapy involving drugs with a sympathomimetic action.
Subject(s)
Bee Venoms/toxicity , Myocardium/metabolism , Norepinephrine/metabolism , Animals , Bee Venoms/administration & dosage , Injections, Intramuscular , Injections, Intraperitoneal , Injections, Intravenous , Injections, Subcutaneous , Male , Myocardium/pathology , Rats , Rats, WistarABSTRACT
The present study was developed in the CMSCVL, which is a primary medical attendment clinic for children and pregnant women, during the period of 01/10/1980 to 31/12/1984, containing 132 children. The study was longitudinal and respective and the two distinct groups of children may be established, differing in accordance to the hospital stay period of postpartum, in rooming-in or traditional nursery. After the statistic analysis of all the variables involved in the study, the only variable that really resulted was the site of internation during the postpartum period. Although these exist a tendency to the greater frequency of breast feeding in the group that utilized the rooming-in, the statistics analysis showed that this difference is not significant. However should consider the important paper carried out by the CMSCVL, in the encouragement of the practice of the breast-feeding, what may have homogenized the two groups. The medium time of weaning found for the population of 132 children studied was 8 months, while for those children that utilized the rooming-in is system was 10 months and for those that stayed in the traditional nursery it took 9 months. The motives of weaning were also identified for the studied population that showed similarity to other published projects.
ABSTRACT
The medical records of 24 patients with Chagas disease who died suddenly, between 1982 and 1988, were examined in an attempt to determine the clinical profile of sudden death in Chagas disease. Patient age ranged from 33 to 72 years (average: 51). Seventeen (70%) were male: Five (20%) were asymptomatic. Dyspnoea at rest was observed in 16 (66%) and palpitations in eight (33%). On physical examination, arrhythmias were observed in 14 (58%), ankle swelling in 13 (54%) and liver enlargement in 12 (50%) patients. Twenty-three (95%) patients had an abnormal resting electrocardiogram: ventricular premature contractions were observed in 19 patients (79%) and a left anterior fascicular block in 14 (58%). The chest X-ray revealed cardiomegaly in 20 patients (82%), which was moderate in three (13%) and severe in 11 (45%). At autopsy, mean heart weight was 496 g. Dilatation of all cardiac chambers was detected in 22 (91%), and apical aneurysm in 19 (79%) patients. When compared with symptomatic patients, asymptomatic patients with Chagas disease had a higher frequency of normal physical examination (3/5 vs 1/19, P < 0.004), normal chest X-ray (3/5 vs 1/19, P < 0.01), and a lower heart weight (400 +/- 43 g vs 521.58 +/- 146.26 g, P < 0.03). The majority of patients with Chagas disease who die suddenly have severe underlying myocardial disease. In some of them, however, sudden cardiac death may occur in the presence of minimal, if any, heart involvement.
Subject(s)
Chagas Cardiomyopathy/pathology , Death, Sudden, Cardiac/etiology , Adult , Aged , Arrhythmias, Cardiac/etiology , Cardiac Complexes, Premature/etiology , Chagas Cardiomyopathy/complications , Chagas Cardiomyopathy/diagnosis , Dyspnea/etiology , Electrocardiography , Female , Heart Aneurysm/etiology , Heart Block/etiology , Humans , Male , Middle AgedABSTRACT
OBJECTIVES: To analyse the concordance between clinical and autopsy diagnoses. DESIGN: Nine-hundred-and-ninety-seven autopsies were studied comparing the diagnoses of the autopsy requests with those of the death certificates and autopsy reports. The cases were grouped according to the 17 categories of diseases of the International Classification of Diseases (ICD) and the concordance was analysed with the kappa (kappa) coefficient of concordance. SETTING: The Hospital da Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (HCFMRPUSP), Ribeirão Preto, SP, Brazil. SUBJECTS: The patients autopsied at HCFMRPUSP during the period between 1978 and 1980. MAIN OUTCOME MEASURES: kappa statistics offer an alternative approach to measuring the concordance between clinical and autopsy diagnoses. RESULTS: The kappa-value obtained was equal to 0.601 with a variance of 1.545 x 10(-4) when comparing the clinical diagnoses and the autopsy diagnoses, and equal to 0.661 with a variance of 1.531 x 10(-4) comparing the clinical diagnoses with those obtained after the gross examination. These values are significant at the level of 5%, i.e. there is an overall statistical concordance between clinical and autopsy diagnoses although the value is not absolute (kappa = 1.00). CONCLUSIONS: If autopsies are heeded without bias, they will continue to give important feedback concerning medical diagnosis.
Subject(s)
Autopsy , Diagnostic Errors , Hospitals, Teaching/standards , Brazil , Humans , Retrospective Studies , Statistics as TopicABSTRACT
The effect of phytohaemagglutinin (PHA) on the adaptation of the proximal jejunal epithelium and on the distal ileal epithelium was studied in rats. The group receiving PHA gained less weight than controls, and the enterocyte population of their jejunal villi, as well as the morphokinetic parameters (length, population, crypt cell production per crypt) of their jejunal and ileal crypts were higher than those of the controls. The proximal lesion caused by PHA (reduction of villus cell populations) stimulates hyperplasia of the crypt-villus unit of the ileal epithelium with the development of adaptation from afar. These adaptations occurred in animals that ingested PHA even in the presence of severe malnutrition.
Subject(s)
Ileum/drug effects , Jejunum/drug effects , Phytohemagglutinins/adverse effects , Administration, Oral , Animal Feed/adverse effects , Animal Nutritional Physiological Phenomena , Animals , Cell Division , Epithelial Cells , Ileum/cytology , Jejunum/cytology , Nutrition Disorders/etiology , Phytohemagglutinins/administration & dosage , Rats , Rats, Inbred Strains , Weight LossABSTRACT
1. The resting electrocardiogram was obtained from 25 Trypanosoma cruzi-infected rats 30 days after infection (phase I). The resting electrocardiogram was abnormal in 12 (group I) and normal in 13 (group II) animals. Nineteen similar but non-infected animals served as controls. Both the resting electrocardiogram and the ajmaline test were performed 120 and 350 days after infection (phases II and III, respectively). 2. With regard to the resting electrocardiogram of group I animals, left axis deviation was found in 10 of 12 (83%) in phase I, one of 12 (8%) in phase II (P less than 0.05) and in none of phase III (P less than 0.05). An intraventricular conduction delay was found in four of 12 (33%) rats in phase I, two of 12 rats (16%) in phase II (P greater than 0.05) and six of 12 rats (50%) in phase III (P greater than 0.05). The ajmaline test was abnormal in nine of 10 (90%) rats of group I with normal resting electrocardiogram in phase II, and in three of six (50%) animals in phase III (P greater than 0.05). 3. An intraventricular conduction delay was found in the resting electrocardiogram of one of 13 (7%) rats of group II in phase III. The ajmaline test was abnormal in one of 13 (7%) rats in phase II and in one of 12 (8%) rats in phase III. 4. No control rat showed pathological changes.(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Chagas Cardiomyopathy/physiopathology , Electrocardiography , Ajmaline/pharmacology , Animals , Chagas Cardiomyopathy/pathology , Electrocardiography/drug effects , Male , Myocardium/pathology , RatsABSTRACT
The jejunum of rats was treated by serosal application of a 0.2% solution of benzalkonium chloride (BAC) for 30 min. Control animals were treated with saline (0.9% NaC1). The animals were allocated to eight groups of 10 rats each and sacrificed 15, 30, 45, 60 days after BAC treatment. Segments were removed from the jejunum for neuronal counting, measurement of the smooth muscle area and morphokinetic study of the epithelium. There was a significant reduction in neuron number in the myenteric plexus 30 days after BAC treatment, thickening of smooth muscle 15-60 days after BAC treatment, but no change in epithelial cell proliferation in the jejunum at either time.
Subject(s)
Benzalkonium Compounds/pharmacology , Jejunum/pathology , Muscle, Smooth/pathology , Animals , Cell Division , Epithelial Cells , Jejunum/innervation , Male , Muscle Denervation , Rats , Rats, Inbred Strains , Time FactorsABSTRACT
STUDY OBJECTIVE: The aim of the study was to evaluate the role of beta receptor antagonists in the evolution of experimental Chagas' disease. DESIGN: Rats were infected with T cruzi, 2000 parasites.g-1 body weight, soon after weaning. One group was then given metoprolol, 100 mg.kg-1.d-1, in drinking water. A comparison group received no metoprolol. Two control groups of non-infected rats were also studied, one with and one without metoprolol in the same dose. SUBJECTS: Adult male albino rats were used: 144 were infected with T cruzi and received metoprolol (group IM), 137 were infected and received no metoprolol (group IW), 46 non-infected rats received metoprolol (group CM), and 43 non-infected rats did not receive metoprolol (group CW). MEASUREMENTS and main results--30 d after infection, resting ECG was performed in all surviving rats. (There were 63 deaths in the infected groups and none in the non-infected groups.) Abnormal ECG was found in 20/81 infected rats in group IM and in 30/74 in group IW (p less than 0.05). No ECG changes were found in the non-infected rats. Of rats in group IM with normal resting ECG, 31 continued to take metoprolol (group IMNM), while 30 similar rats did not (group IMNW); in group IM with abnormal ECG, 10 rats continued to take metoprolol (group IMAM), while 10 similar rats did not (group IMAW). Of rats in group IW with normal ECG, 22 were started on metoprolol (group IWNM), while 22 similar rats were not (group IWNW); in group IW with abnormal ECG, 15 rats were started on metoprolol (group IWAM), while 15 similar rats did not (group IWAW). After 120 d and 300 d infection there were no differences in mortality rate and Ajmaline test in any of the matched groups (IMNM X IMNW; IMAM X IMAW; IWNM X IWNW; IWAM X IWAW). After 120 d there was no difference in ECG between the groups, but after 300 d there was a decrease in abnormal ECG in group IWAM (IWAM v IWAW, 0/12 v 5/12, p less than 0.05). No histological differences were found. CONCLUSIONS: Metoprolol decreases the proportion of rats with abnormal resting ECG in both the acute and the chronic stage of T cruzi infection.