Disfunção autonômica e arritmia ventricular em chagásicos sem cardiopatia aparente

Estresse ortostático ativo e arritmia sinusal respiratória em chagásicos com função sistólica global do ventrículo esquerdo preservada

“…However, we know no report about the use of the max:min RR ratio for detecting vagal dysfunction in Chagas' disease on an outpatient care basis. The active orthostatic stress test is sensitive, specific, reproducible, and easily performed, being con- Table I The results of the active orthostatic stress test in chagasic patients with no heart disease, as compared with that in normal controls, confirm the findings of our previous study performed in the same group of patients [4][5][6] , and in another sample later studied 7,8 , and also the findings reported by other authors [24][25][26][27] . The different methods used, such as the variability in heart rate (assessed with different techniques) 5,7,8,22 , the Valsalva maneuver 6,23,24,26 , and respiratory sinus arrhythmia 5,26 , showed that autonomic dysfunction is present in patients with no evidence of heart disease and with preserved left ventricular function.…”

“…A cross-sectional study was carried out in the referral outpatient care clinic for Chagas' disease of the Hospital das Clínicas of the UFMG, after approval of the research project by the committee on ethics in research of the institution 4 . The patients were screened up from January 1992 to August 1994, and those, chagasic or not, in the age group from 15 to 50 years with a defined serology for Chagas' disease were recruited.…”

“…Each patient was prompted to slowly perform maximum respiratory movements, each respiratory cycle lasting 10 seconds. A simply codified manual mark was performed on the electrocardiogram at the beginning of each inspiration and expiration in each respiratory cycle 4,[12][13][14][15][16] .…”

“…The 10 RR intervals immediately preceding maneuver onset were computed to obtain the mean cardiac interval and mean heart rate at baseline immediately before starting the maneuver. The longest and shortest RR intervals were recorded right after the maneuver, and the max:min RR index was calculated 4,[8][9][10][11][12][13][14][15][16] .…”

“…Autonomic dysfunction, a typical abnormality of the disease, has been implicated as playing an important role in the genesis of arrhythmic death in Chagas' disease 3 . Recent studies [4][5][6][7][8] have reported that vagal dysfunction can be observed in patients with no left ventricular dysfunction, occurring early in some patients with the disease. It can be recognized with the study of heart rate variability on 24-hour Holter, of respiratory sinus arrhythmia, and the Valsalva maneuver.…”