SPECIAL SECTION: LETTER TO THE EDITOR
Sympathetic nervous system activation in chagasic patients with congestive heart failure
Diego F. Davila, MD, PhD
Apartado Postal 590, Instituto de Investigaciones Cardiovasculares, Mérida, Venezuela
diegod{at}ula.ve
The pathogenesis and the medical treatment of chronic Chagas' disease are still subjects of intense controversy and research (1–5). In the study by Roveda et al. published in the Journal (6), exercise training decreased sympathetic nervous system activation in patients with congestive heart failure. It should be pointed out that 5 of 16 patients were of chagasic etiology (31.25%). As stated by the investigators, four of these patients were in the sedentary group and one in the exercise group. The former continued to have increased sympathetic activity, whereas the latter showed a significant and beneficial decrease in the degree of sympathetic activation. Moreover, resting muscle sympathetic nerve activity was now similar to trained healthy control subjects.
These findings raise several relevant questions: Was the degree of sympathetic nervous system activation of chagasic patients similar to that of non-chagasic patients? If so, chagasic patients with congestive heart failure do not have sympathetic dysautonomia (7–9). Also, are the mechanisms responsible for sympathetic activation and exercise training-induced beneficial effects in chagasic patients similar to those of non-chagasic patients (10,11)? Finally, do these results indirectly suggest that chagasic patients with congestive heart failure would benefit from therapeutic strategies that antagonize sympathetic nervous system activation (12)?
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References
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11. Barreto-Filho JAS, Consolim-Colombo FM, Lopes HF, et al. Dysregulation of peripheral and central chemoreflex responses in Chagas' heart disease patients without heart failure. Circulation. 2001;104:1792–1798[Abstract/Free Full Text]
12. Davila DF, Angel F, Donis JH, Arata de Bellabarba G. Effects of metoprolol in chagasic patients with severe congestive heart failure. Int J Cardiol. 2002;85:255–260[Medline]
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