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Response of heart rate to atropine and left ventricular function in Chagas' heart disease
D F Davila1, J H Donis, M Navas
1Centro Cardiovascular, Universidad de Los Andes, Merida, Venezuela.
Insights
Heart rate response to atropine indicates severity of left ventricular dysfunction in Chagas disease patients. An abnormal response signifies more severe myocardial damage and left ventricular dilatation.
Area of Science:
- Cardiology
- Infectious Diseases
- Physiology
Background:
- Chagas disease, caused by Trypanosoma cruzi, frequently leads to cardiac complications, including left ventricular dysfunction.
- The autonomic nervous system's role in Chagasic cardiomyopathy is not fully understood, particularly the heart rate response to autonomic challenges.
- Atropine, an anticholinergic agent, can reveal alterations in cardiac autonomic function by assessing heart rate response.
Purpose of the Study:
- To investigate the relationship between heart rate response to atropine and the degree of left ventricular dysfunction in Chagas disease patients.
- To assess whether atropine response can serve as a marker for myocardial damage and left ventricular dilatation in this population.
Main Methods:
- Ventricular cineangiography and coronary arteriography were used to evaluate left ventricular wall motion and volumes.
- 33 Chagas disease patients (positive complement fixation test) and 11 sero-negative controls were studied.
- Patients were categorized based on their heart rate response to atropine (normal >40 beats/min, abnormal <40 beats/min).
Main Results:
- Chagasic patients with an abnormal heart rate response to atropine exhibited diffuse left ventricular hypokinesis and significantly increased end-diastolic volumes (192 +/- 49 ml/m2).
- Patients with a normal atropine response had a higher prevalence of left ventricular apical aneurysms, with end-diastolic volumes not significantly different from controls (96 +/- 26 ml/m2).
- A significant inverse correlation (r = -0.88, P < 0.01) was found between heart rate response to atropine and left ventricular end-diastolic volume in Chagasic patients.
Conclusions:
- An abnormal heart rate response to atropine in Chagas disease patients is associated with more severe myocardial damage and left ventricular dilatation.
- The degree of left ventricular dysfunction and dilatation is inversely correlated with the heart rate response to atropine.
- Atropine response may be a valuable indicator of the severity of cardiac involvement in Chagas disease.
Abstract:
Chagasic patients may have a normal or abnormal response of heart rate to atropine. To determine if this response to atropine is related to the degree of left ventricular dysfunction, we studied 33 patients with a positive complement fixation test for Chagas' disease. Eleven subjects, with atypical chest pain and negative complement fixation test, were used as controls (sero-negative). Left ventricular wall motion and the left ventricular volumes were determined by ventricular cineangiography. Coronary arteriography was also performed. The sero-negative subjects had normal left ventricular wall motion and the left ventricular diastolic volume was 88 +/- 24 ml/m2. The response of heart rate to atropine was 50 +/- 8 (mean +/- SD) (range 40-65 beats/min). On the basis of the response to atropine, the chagasic patients were divided into groups with a normal response (greater than 40 beats/min) and those with an abnormal response (less than 40 beats/min). Sixty five per cent of those with a normal response had left ventricular apical aneurysms. The left ventricular end-diastolic volume was not significantly different from the sero-negative subjects (96 +/- 26 ml/m2). Six patients (30%) had a left ventricular diastolic volume between 110 and 140 ml/m2. Sixty two per cent of those chagasic subjects with an abnormal response had diffuse left ventricular hypokinesis, and the left ventricular end-diastolic volume was 192 +/- 49 ml/m2 (P less than 0.01). The response of heart rate and the left ventricular diastolic volume were inversely correlated in the chagasic patients (r = -0.88, P less than 0.01). Our results indicate that myocardial damage and the degree of left ventricular dilatation are more severe in chagasic patients with an abnormal response of their heart rate to atropine. Furthermore, the inverse correlation between these two variables is highly indicative of a relationship between the response of heart rate to atropine and the degree of left ventricular dysfunction.