Active orthostatic stress and respiratory sinus arrhythmia in patients with Chagas' disease with preserved left ventricular global systolic function.

Objective: To assess the use of the active orthostatic stress test for detecting vagal dysfunction in patients with Chagas' disease with preserved overall systolic function, and to compare it with the respiratory sinus arrhythmia test.

Methods: Sixty-one chagasic patients (Ch) and 38 nonchagasic (NCh) patients with no significant evidence of heart disease or systemic diseases underwent Doppler echocardiography and autonomic function tests. The respiratory sinus arrhythmia test was performed through electrocardiographic recording during deep breathing, at 6 ripm, calculating the E:I ratio (mean ratio between the longest expiratory RR interval and the shortest inspiratory RR interval at each cycle).

Aedes albopictus may not be vector of dengue virus in human epidemics in Brazil.

Over 60,500 dengue cases were reported in the state of Espírito Santo (ES), Brazil, between 1995 and 1998. The study's purpose was to identify whether Aedes albopictus was transmitting the dengue virus during an epidemic in the locality of Vila Beth nia (Viana County),Vitória, ES. From April 3 to 9, 1998, blood and serum samples were collected daily for virus isolation and serological testing.

The Valsalva maneuver in Chagas disease patients without cardiopathy.

Background: The Valsalva maneuver is a simple and reliable test of parasympathetic heart control that can also be used as a trigger of cardiac arrhythmia. Few studies are available about the Valsalva maneuver in Chagas disease patients without cardiac involvement and their results are contradictory. In a cross-sectional study, we compared Chagas disease patients without cardiac involvement and normal individuals using the Valsalva maneuver in order to study the vagal cardiac control and the occurrence of cardiac arrhythmia in the early phase of Chagas disease.