Cardiac autonomic function in chagasic elderly patients in an endemic area: A time and frequency domain analysis approach.

Chagas' disease is a common cause of cardiac autonomic impairment. In an endemic area there is a predominance of the indeterminate form and the number of elderly individuals committed by the disease is increasing. This study aimed to investigate the profile of heart rate variability (HRV) in elderly chagasic patients. 28 aged chagasic (CH), 28 non-chagasic (NC) aged individuals and 28 adults between 20 and 40 years old (YG) were studied. R-R intervals were assessed in time and frequency domains applying an autoregressive algorithm. There was no difference regarding temporal and spectral indices among the elderly groups in baseline. The values of the variance in CH, NC and YG individuals were 891.80, 283.60, 2557.00, showing a reduction of the total HRV in the aged groups when compared to the young control (p < 0.001). During the cold face test, the pNN50 response was significantly different only in the young group (p < 0.001). The temporal and spectral indices were not different among the elderly groups. The percentile changes of the R-R intervals induced by the tilt test in CH, NC and YG were respectively -7.04%, -9.35%, -15.81%, being significantly higher in the young individuals (p < 0.001). There was no difference regarding the percentile changes of the temporal and spectral indices between CH and NC elderly patients. The cardiac autonomic function assessed by HRV parameters presented no differences among the elderly individuals (CH and NC) living in an endemic area.

Análise temporal da variabilidade da freqüência cardíaca no estado basal em idosos chagásicos na forma indeterminada em área endêmica / Temporal analysis of cardiac frequency variability in basal condition in elderly chagasic subjects in indeterminate form in endemic área

Com o objetivo de avaliar a função autonômica cardíaca em pacientes chagásicos residentes em área endêmica, foram avaliados, por meio da análise computadorizada da variabilidade da freqüência cardíaca, 28 pacientes idosos chagásicos na forma indeterminada, 28 pacientes idosos não-chagásicos e 28 adultos jovens. Todos os pacientes chagásicos realizaram eletrocardiograma, radiografia de tórax, estudo radiológico contrastado do esôfago e cólons e ecodopplercardiograma, sendo que os não-chagásicos deixaram de realizar apenas os exames contrastados. Não houve diferença estatisticamente significativa entre os grupos, quanto às dimensões sistólica e diastólica e função sistólica do ventrículo esquerdo. Não houve diferença estatisticamente significante entre os grupos, quanto à duração média do intervalo RR. Quanto à variância, desvio padrão, coeficiente de variação, e ao pNN50, houve diferença estatisticamente significante entre o grupo jovem e os idosos, mas não entre os grupos idosos. Concluímos que, no estado basal, os grupos idosos chagásicos e não-chagásicos não diferiram quanto à modulação autonômica cardíaca no domínio do tempo.

[Temporal analysis of cardiac frequency variability in basal condition in elderly chagasic subjects in indeterminate form in endemic área]. / Análise temporal da variabilidade da freqüência cardíaca no estado basal em idosos chagásicos na forma indeterminada em área endêmica.

With the aim of evaluating the cardiac autonomic function in elderly chagasic patients living in an endemic area, we evaluated, by using computadorized heart rate variability, 28 elderly chagasic with the indeterminate form, 28 elderly non chagasic and 28 young healthy control. In all patients we performed conventional electrocardiogram, radiological investigation of thorax, and with contrast of esophagus and colons and echodopplercardiogram. Non chagasic patients did not perform only the exams with contrast. The systolic ventricular function was preserved in all subjects. There was no statistically significant difference between the groups with regard to mean duration of RR intervals. Considering the variance, standard deviation, variation coefficient and pNN50 there was statistically significant difference between the young and elderly groups but no difference was found when the analysis was performed in each one separately for these temporal indexes. We conclude that, in basal condition, the groups of elderly chagasic and no chagasic subjects did not differ as much as the cardiac autonomic modulation in time domain.