Association of Bartonella spp bacteremia with Chagas cardiomyopathy, endocarditis and arrythmias in patients from South America

Infection with Bartonella spp may cause cardiac arrhythmias, myocarditis and endocarditis in humans. The aim of the present study was to evaluate a possible association between Bartonella spp bacteremia and endocarditis, arrhythmia and Chagas cardiomyopathy in patients from Brazil and Argentina. We screened for the presence of bacterial 16S rRNA in human blood by PCR using oligonucleotides to amplify a 185-bp bacterial DNA fragment. Blood samples were taken from four groups of subjects in Brazil and Argentina: i) control patients without clinical disease, ii) patients with negative blood-culture endocarditis, iii) patients with arrhythmias, and iv) patients with chronic Chagas cardiomyopathy. PCR products were analyzed on 1.5% agarose gel to visualize the 185-bp fragment and then sequenced to confirm the identity of DNA. Sixty of 148 patients (40.5%) with cardiac disease and 1 of 56 subjects (1.8%) from the control group presented positive PCR amplification for Bartonella spp, suggesting a positive association of the bacteria with these diseases. Separate analysis of the four groups showed that the risk of a Brazilian patient with endocarditis being infected with Bartonella was 22 times higher than in the controls. In arrhythmic patients, the prevalence of infection was 45 times higher when compared to the same controls and 40 times higher for patients with Chagas cardiomyopathy. To the best of our knowledge this is the first report of the association between Bartonella spp bacteremia and Chagas disease. The present data may be useful for epidemiological and prevention studies in Brazil and Argentina.

Early remodeling of rat cardiac muscle induced by swimming training

The aim of the present investigation was to study the effect of acute swimming training with an anaerobic component on matrix metallopeptidase (MMP) activity and myosin heavy chain gene expression in the rat myocardium. Animals (male Wistar rats, weighing approximately 180 g) were trained for 6 h/day in 3 sessions of 2 h each for 1 to 5 consecutive days (N = 5 rats per group). Rats swam in basins 47 cm in diameter and 60 cm deep filled with water at 33 to 35°C. After the training period a significant increase (P < 0.05) was observed in the heart weight normalized to body weight by about 22 and 35 percent in the groups that trained for 96 and 120 h, respectively. Blood lactate levels were significantly increased (P < 0.05) in all groups after all training sessions, confirming an anaerobic component. However, lactate levels decreased (P < 0.05) with days of training, suggesting that the animals became adapted to this protocol. Myosin heavy chain-ß gene expression, analyzed by real time PCR and normalized with GAPDH gene expression, showed a significant two-fold increase (P < 0.01) after 5 days of training. Zymography analysis of myocardium extracts indicated a single ~60-kDa activity band that was significantly increased (P < 0.05) after 72, 96, and 120 h, indicating an increased expression of MMP-2 and suggesting precocious remodeling. Furthermore, the presence of MMP-2 was confirmed by Western blot analysis, but not the presence of MMP-1 and MMP-3. Taken together, our results indicate that in these training conditions, the rat heart undergoes early biochemical and functional changes required for the adaptation to the new physiological condition by tissue remodeling.

Heart rate variability under resting conditions in postmenopausal and young women

The aim of the present study was to compare the modulation of heart rate in a group of postmenopausal women to that of a group of young women under resting conditions on the basis of R-R interval variability. Ten healthy postmenopausal women (mean Ý SD, 58.3 Ý 6.8 years) and 10 healthy young women (mean Ý SD, 21.6 Ý 0.82 years) were submitted to a control resting electrocardiogram (ECG) in the supine and sitting positions over a period of 6 min. The ECG was obtained from a one-channel heart monitor at the CM5 lead and processed and stored using an analog to digital converter connected to a microcomputer. R-R intervals were calculated on a beat-to-beat basis from the ECG recording in real time using a signal-processing software. Heart rate variability (HRV) was expressed as standard deviation (RMSM) and mean square root (RMSSD). In the supine position, the postmenopausal group showed significantly lower (P<0.05) median values of RMSM (34.9) and RMSSD (22.32) than the young group (RMSM: 62.11 and RMSSD: 49.1). The same occurred in the sitting position (RMSM: 33.0 and RMSSD: 18.9 compared to RMSM: 57.6 and RMSSD: 42.8 for the young group). These results indicate a decrease in parasympathetic modulation in postmenopausal women compared to young women which was possibly due both to the influence of age and hormonal factors. Thus, time domain HRV proved to be a noninvasive and sensitive method for the identification of changes in autonomic modulation of the sinus node in postmenopausal women

Electrocardiographic characterization of myocardial function in normoxic and hypoxic teleosts

Electrocardiography was applied to analyze cardiac function of four teleost species (Piaractus mesopotamicus, Hoplias malabaricus, Hoplias lacerdae and Cyprinus carpio) during normoxia and graded hypoxia. In these species, hypoxic bradycardia consistently occurred during severe hypoxia (below the critical oxygen tension - PcO2) and was accompanied by alterations in the ECG recordings. Three basic ECG alterations were demonstrable: 1) increase in the T wave area and amplitude, being more positive and with symmetrical morphology during severe hypoxia (P. mesopotamicus); 2) negative T wave in normoxia, changing to isodiphasic (Just above the PcO2) and positive (below the PcO2; H. malabaricus and H. lacerdae); 3) positive T wave in normoxia, changing to negative in severe hypoxia (5 mmHg; Cyprinus carpio). These findings indicate changes in the direction of ventricular repolarization during exposure to severe hypoxia, and the analysis of the ECGs in relation to the derivation line permitted the estimation of these drifts to be 17 degrees in P. mesopotamicus, 46 degrees in H. malabaricus, 43 degrees in H. lacerdae, and 32 degrees in C. carpio. The changes in the direction of ventricular repolarization were attributed to myocardial impairment due to insufficient oxygen supply, and support the idea of a relationship between cardiac dysfunction and the bradycardia developed during severe hypoxia.

Magnetocardiography in normal subjects and in patients with right bundle branch block

The initial results of a rnagnetocardiographic study comparing normal subjects to patients with right bundle branch block due to Chagas' and other diseases is presented. A quantitative criterion to discriminate normal healthy individuals from patients was proposed based on the amplitude of R and S waves detected by the magnetocardiograrn.

Fetal heart rate monitoring by magnetocardiograms

The magnetic field produced by the fetal heart magnetocardiogram (FMCG) was measured by a single channel SQUID biogradiometer in an unshielded environment. FMCG amplitude ranged from 1 to 4 pT. Instantaneous fetal heart rate and averaged FMCG waveforms were computed. Spectral analysis was used to quantify fetal heart rate variability, and revealed peaks from 0.5 to 1.0 Hz, consistent with respiratory sinus arrhythmia. The duration of the QRS complex was approximately 50 msec, and its amplitude and shape showed strong spatial variation. Signal-to-noise ratio was inadequate for the study of P and T waves. These data show that this relatively simple and inexpensive instrument can be used for noninvasive in utero investigation of fetal heart activity without requiring a special environment.