In the present protocol, adult dogs were infected with Trypanosoma cruzi, Bolivian strain, in order to show electrocardiographic changes by means of resting and dynamic (Holter) methods during acute and chronic phases of Chagas disease. In the acute phase there were sinus tachycardia, atrial and left ventricular overload, millivoltage suppression, electric alternance, and episodes of sinus arrest. At the parasitemia peak, atrium-ventricular block, junctional escape complexes, and atrium-ventricular dissociation were observed. Dogs that presented the most serious arrhythmias died suddenly. The increase in supraventricular and ventricular arrhythmic events, concentrated in the 4th postinoculation week, was visible at electrocardiographic monitoring. In the chronic phase, the events were restricted to first-degree atrium-ventricular blocks, premature ventricular complexes, ventricular bigeminy, and electrical alternation. It was concluded that the computerized and dynamic electrocardiography allowed to diagnose transient arrhythmia and to observe that the main tachyarrhythmic changes are concentrated at the acute phase concomitantly to the parasitemia peak. 1. Introduction Even a century after its discovery, Chagas disease remains a significant public health problem whose pathogenesis is not well understood, which perpetuates it as an intriguing challenge arising from the complex host-parasite interaction. It is an American exclusive endemic disease, which goes from the southern United States to southern Argentina, and it represents a major cause of morbidity and mortality in Latin America [1]. Currently, 10 million people living between Mexico and Argentina are infected, 10.000 people died only in 2008 as a result of this disease, and it is estimated that 28 million people are at high risk of acquiring it [2]. Dogs have been considered an important domestic reservoir of the parasite and also serve as a sentinel to detect infection in humans [3], requiring more attention by the scientific community [4]. Moreover, it is considered a suitable experimental model to the study of Chagas disease, because it is the only one so far to develop all phases of the disease, and showing similar manifestations as in humans. Considering this scenario, in the present protocol, adult dogs were infected with Trypanosoma cruzi, Bolivian strain, with the purpose of showing the electrocardiographic changes produced by this strain during the acute and chronic phases of the disease and, thus, providing more accurate and enlightening data about this disease. 2. Materials and
References
[1]
J. A. Marin-Neto, C. Bern, S. P. Montgomery et al., “Evaluation and treatment of chagas disease in the United States: a systematic review,” Journal of the American Medical Association, vol. 298, no. 18, pp. 2171–2181, 2007.
[2]
World Health Organization, “Division of Control of Tropical diseases, Elimination of Chagas disease as a Public Health Problem,” Projected costs 1997-2010, Geneva, CTD/TRY/97.14 p. 41.
[3]
S. P. Pavarini, E. C. Oliveira, P. M. Bandarra et al., “Miocardite chagásica em caninos no Estado do Rio Grande do Sul,” Ciencia Rural, vol. 39, no. 4, pp. 1243–1247, 2009.
[4]
J. P. Pascon, G. B. Pereira Neto, M. G. Sousa, D. Paulino Júnior, and A. A. Camacho, “Clinical characterization of chronic chagasic cardiomyopathy in dogs,” Pesquisa Veterinária Brasileira, vol. 30, no. 2, pp. 115–120, 2010.
[5]
Z. Brener, “Therapeutic activity and criterion of cure on mice experimentally infected with Trypanosoma cruzi,” Revista do Instituto de Medicina Tropical de S？o Paulo, vol. 4, no. 6, pp. 389–396, 1962.
[6]
M. E. Camargo, Introdu？？o às Técnicas de Imunofluorescência, Instituto de Medicina Tropical, S？o Paulo, Brazil, 1973.
[7]
L. P. Tilley, Essentials of Canine and Feline Electrocardiography, Lea & Febiger, Philadelphia, Pa, USA, 3rd edition, 1992.
[8]
R. Wolf, A. A. Camacho, and R. C. A. Souza, “Eletrocardiografia computadorizada em c？es,” Arquivo Brasileiro de Medicina Veterinária e Zootecnia, vol. 52, no. 6, pp. 610–615, 2000.
[9]
G. W. Snedecor and W. G. Cochran, Statistical Methods, Iowa State University Press, Ames, Iowa, USA, 1980.
[10]
I. B. M. Sampaio, Estatística Aplicada a Experimenta？？o, FEPMVZ, Belo Horizonte, Brazil, 1998.
[11]
R. P. Klein, “Avalia？？o clínica e contagem neuronal em ganglios nervosos cardíacos em c？es experimentalmente infectados com Trypanosoma cruzi,” in Disserta？？o (Mestrado em Medicina Veterinária), Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista, Jaboticabal, Brazil, 1995.
[12]
S. C. Barr, K. A. Gossett, and T. R. Klei, “Clinical, clinicopathologic, and parasitologic observations of trypanosomiasis in dogs infected with North American Trypanosoma cruzi isolates,” American Journal of Veterinary Research, vol. 52, no. 6, pp. 954–960, 1991.
[13]
P. Penin, C. Gamallo, and J. A. De Diego, “Biological comparison between three clones of Trypanosoma cruzi and the strain of origin (Bolivia) with reference to clonal evolution studies,” Memórias do Instituto Oswaldo Cruz, vol. 91, no. 3, pp. 285–291, 1996.
[14]
E. S. G. Lopes and J. C. P. júnior, “A influência da cepa y de Trypanosoma cruzi no cora？？o em ratos wistar machos submetidos ao processo de adrenalectomia,” Biodiversidade, vol. 6, no. 1, pp. 62–76, 2007.
[15]
A. Y. N. Pinto, S. A. Valente, V. C. Valente, A. G. F. Junior, and J. R. Coura, “Fase aguda da doen？a de Chagas na Amaz？nia Brasileira. Estudo de 233 casos do Pará, amapá e maranh？o observados entre 1988 e 2005,” Revista da Sociedade Brasileira de Medicina Tropical, vol. 41, no. 6, pp. 602–614, 2008.
[16]
S. C. Barr, R. A. Holmes, and T. R. Klei, “Electrocardiographic and echocardiographic features of trypanosomiasis in dogs inoculated with North American Trypanosoma cruzi isolates,” American Journal of Veterinary Research, vol. 53, no. 4, pp. 521–527, 1992.
[17]
Z. A. Andrade, S. G. Andrade, M. Sadigursky, R. J. Wenthold, S. L. Hilbert, and V. J. Ferrans, “The indeterminate phase of Chagas' disease: ultrastructural characterization of cardiac changes in the canine model,” American Journal of Tropical Medicine and Hygiene, vol. 57, no. 3, pp. 328–336, 1997.
[18]
A. A. Camacho, M. S. S. Teixeira, and R. Oliveira Alves, “Electrocardiography in adult dogs infected with Trypanosoma cruzi during acute and chronic phases,” Ars Veterinaria, vol. 16, no. 3, pp. 158–164, 2000.
[19]
Z. Brener and Z. A. Andrade, Trypanosoma cruzi e Doen？a de Chagas, 2nd edition, 2000, Edited by G. Koogan.
[20]
S. F. Brenière, M. F. Bosseno, and F. Noireau, “Integrate study of a Bolivian population infected by Trypanosoma cruzi, the agent of Chagas disease,” Memórias do Instituto Oswaldo Cruz, vol. 97, no. 3, pp. 289–295, 2002.
[21]
G. Punukollu, R. M. Gowda, I. A. Khan, V. S. Navarro, and B. C. Vasavada, “Clinical aspects of the Chagas' heart disease,” International Journal of Cardiology, vol. 115, no. 3, pp. 279–283, 2007.
[22]
M. Lana, E. Chiari, and W. L. Tafuri, “Experimental Chagas' disease in dogs,” Memórias do Instituto Oswaldo Cruz, vol. 87, no. 1, pp. 59–71, 1992.
[23]
J. C. Pinto Dias, “Notas sobre o Trypanosoma cruzi e suas características bioecológicas, como agente de enfermidades transmitidas por alimentos,” Revista da Sociedade Brasileira de Medicina Tropical, vol. 34, no. 4, pp. 370–375, 2006.
[24]
H. Germiniani, Diagnóstico e terapêutica das arritmias cardíacas, Rio de Janeiro, Brazil, 3rd edition, 1990, Edited by G. Koogan.
[25]
A. Rassi Jr., A. Rassi, and J. A. Marin-Neto, “Chagas disease,” The Lancet, vol. 375, no. 9723, pp. 1388–1402, 2010.
[26]
A. A. J. Fuenmayor and P. A. M. Fuenmayor, “Muerte subita en pacientes com miocarditis chagásica,” Archivos del Instituto de Cardiología de México, vol. 66, no. 2, pp. 157–161, 1996.
[27]
F. J. Carod-Artal, A. P. Melo, and T. A. Horan, “American trypanosomiasis (Chagas' disease): an unrecognised cause of stroke,” Journal of Neurology Neurosurgery and Psychiatry, vol. 74, no. 4, pp. 516–518, 2003.
