Cardiac autonomic and ventricular mechanical functions in asymptomatic chronic chagasic cardiomyopathy.
BACKGROUND
The association of variably altered cardiac autonomic and ventricular systolic and diastolic functions is still controversial and little explored in chronic Chagas' disease.


OBJECTIVE
To evaluate the extent to which cardiac autonomic and mechanical ventricular functions are altered and whether they are associated in asymptomatic chagasic cardiomyopathy.


METHODS
A total of 13 patients with asymptomatic chagasic cardiomyopathy and 15 normal subjects (control group) were evaluated and the autonomic modulation of heart rate variability for five minutes, in the temporal and spectral domains, in the supine and orthostatic positions, as well as ventricular function based on morphological-functional variables obtained by Doppler echocardiography were correlated. Statistical analysis used the Mann-Whitney test and Spearman's correlation.


RESULTS
In both positions, the temporal index (p = 0.0004 to 0.01) and total (p = 0.0007-0.005) and absolute spectral areas, of low and high frequencies (p = 0.0001 to 0.002), were lower in the chagasic group. The vagal-sympathetic balance was similar in both positions (p = 0.43 to 0.89). The echocardiographic variables did not differ between groups (p = 0.13 to 0.82), except the left ventricular end-systolic diameter, which was larger (p = 0.04) and correlated directly with reduced rates of global (p = 0.01 to 0.04) and parasympathetic (p = 0.002 to 0.01) autonomic modulation in patients with Chagas disease in the orthostatic position.


CONCLUSIONS
The sympathetic and parasympathetic depressions with preserved balance were associated with only one ventricular dysfunction indicator. This suggests that cardiac autonomic dysfunction may precede and be independently more severe than ventricular dysfunction, with no causal association between both disorders in chronic chagasic cardiomyopathy.
Laboratório Cardiovascular, Faculdade de Medicina, Universidade de Brasília, DF, Brasil. dfrancav@cardiol.br
Daniel França
DF
Vasconcelos
Luiz Fernando
LF
Junqueira
D000328:Adult; D001342:Autonomic Nervous System Diseases / Q000145:classification / Q000503:physiopathology*; D016022:Case-Control Studies; D002598:Chagas Cardiomyopathy / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002908:Chronic Disease; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology*; D018709:Statistics, Nonparametric; D013599:Systole; D013997:Time Factors; D014463:Ultrasonography; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000503:physiopathology*