Sera from 58 chronic chagasic patients decreased heart rate in 26 cases and blocked AV conduction in 20 cases when tested in isolated rabbit hearts.
Does sera from chronic chagasic patients affect cardiac electrogenesis and conduction in isolated heart models?
Sera from chronic chagasic patients can depress heart rate and AV conduction through muscarinic and other mechanisms, potentially contributing to arrhythmogenesis.
We report results obtained with sera from 58 chronic chagasic patients that were evaluated for effects on heart rate and atrioventricular (AV) conduction in isolated rabbit hearts and screened for the presence of muscarinic and beta-adrenergic activity. We show that sera from 26 patients decreased heart rate, while 10 increased it and 22 had no effect. Additionally, sera from 20 of the 58 patients blocked AV conduction. Muscarinic activation seems to be involved in both effects, but is not the only mechanism, since atropine did not antagonize the decrease in heart rate in 23% of sera or AV block in 40%. Sera from patients with complex arrhythmias were significantly more effective in depressing both heart rate and AV conduction. Sera that induce increases in heart rate seem to operate exclusively through beta-adrenergic activation. Two of these sera, evaluated with respect to intercellular communication in primary cultures of embryonic cardiomyocytes were able to block gap junction conductance evaluated by a dye injection technique after 24-h exposure. The mechanisms underlying this uncoupling effect are currently being investigated.
Costa et al. (2000) studied Chronic Chagas disease (n=58). Sera from chronic chagasic patients was evaluated on Effects on heart rate and atrioventricular (AV) conduction. Sera from 58 chronic chagasic patients decreased heart rate in 26 cases and blocked AV conduction in 20 cases when tested in isolated rabbit hearts.