Sinus node involvement in Chagas' disease
Andrade, Z.A.; Câmara, E.J.; Sadigursky, M.; Andrade, S.G.
Arquivos Brasileiros de Cardiologia 50(3): 153-158
1988
ISSN/ISBN: 0066-782X PMID: 3228363 Document Number: 322957
Marked diffuse fibrosis plus atrophy and fragmentation of specific fibres were found in all 11 sinus nodes examined by serial sections from subjects with chronic chagasic heart disease. The sinus lesion resembled a scar, in contrast to the chronic inflammation present in the contractile myocardium. A clinically detectable sinus syndrome was found only in one patient. However, the pathological findings suggest that the involvement of the sinus node in Chagas' disease is frequent and that its clinical expression may pass unnoticed. In additional experimental studies a double autonomic blockade was produced in 7 young dogs with acute chagasic myocarditis by means of atropin (0.4 mg/kg) and propranolol (2.25 mg/kg) in order to obtain the intrinsic sinus rate. This rate reached 169 +or- 5.4 before infection. 18 days later, 60% of the animals showed a decreased intrinsic sinus rate, which was considered as sinus node dysfunction. Severe inflammatory changes were found in the myocardium as well as within the sinus node, causing its partial destruction. Thus, the sinus node appears vulnerable to change in chagasic cardiopathy, apart from indirect changes involving the intrinsic autonomic nervous system.