Parámetros que mejor identifican la presencia de la miocardiopatía chagásica a partir del electrocardiograma superficial
Palabras clavesHigh frequency electrocardiography Chagas disease Heart rate variability
This paper reports the evaluation of a high fidelity ECG hardware/software (CardioSoft, Houston, TX), in a group of chronic chagasic patients.
It has been observed that several electrocardiographic abnormalities that are present in Chagas’patients, also occur in the Brugada syndrome, which involves genetically defective cardiac sodium channels, This fact suggests that acquired damage to cardiac sodium channels may also occur in Chagas’ disease.
We compared several conventional and advanced resting 12-lead and derived Frank-lead ECG parameters in 34 Chagas’ seropositive patients (studied at the Universidad de Los Andes) to those in 34 age-and gender-matched healthy controls (studied at NASA’s Johnson Space Center).
Chagas’ patients who had resting (Bundled Branch Block) BBBs, (Left Ventricle Hypertrophy) LVH criteria by conventional ECG, pathologic arrhythmias and/or echocardiographic ejection fractions (EFs) < 40% (n=10) were excluded, however, for the rest of patients significant differences persisted in multiple conventional and advanced ECG parameters between the Chagas’ and control subjects (n=24/group), especially in their respective J-Tpeak interval durations, QT interval variability indices, T-wave axes and low frequency (Heart Rate Variability) HRV powers (p=0.001, p=0.001, p=0.006 and p=0.025 respectively). Concerning the potential changes in transmural dispersion of repolarization and cardiac sodium channel function, the Chagas’ seropositive patients also had: 1) significantly increased corrected Tpeak-Tend interval durations versus controls (97 ± 9 vs. 91 ± 10 ms, p=0.05); 2) significantly decreased corrected J-Tpeak interval durations versus controls (212 ± 19 versus 226 ± 18 ms; p=0.009) and 3) more than twice the incidence of resting ST segment elevation in any of leads V1-V3 and of both leftward and rightward QRS axis deviation than controls.
Chagas’ patients with preserved (Left Ventricle) LV systolic function have untoward changes in cardiac repolarization, including decreased corrected J-Tpeak intervals and increased corrected Tpeak-Tend intervals (‘TDR’) and (QT variability) QTV, potentially suggesting an acquired loss of cardiac sodium channel function.
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