A Study on Ventricular Late Potentials by Signal Averaged Electrocardiogram in Myocardial Infarction Patients.

Fifty patients who presented with Myocardial Infarction (MI), diagnosed by history, ECG, enzymes were subjected to late potential analysis between 7-10 days post MI by Signal Averaged Electrocardiography (SAECG). There were 42 male and 8 female patients. 34 had anterior wall MI and 16 had inferior wall MI, and all of them had Q wave infarction. History of previous MI in 12, diabetes in 14, hypertension in 34, smoking in 24 and hypercholesterolemia in 8 was noted. Patients were followed up for one year. Late potentials were positive in 10 patients (62.5%) of inferior wall MI and 6 patients (17.5%) of anterior wall MI. Those with episodes of ventricular tachycardia had increased incidence of late potentials. There was no correlation of late potentials and LV function assessed by echocardiography. Thrombolysed group had decreased incidence of late potentials.

The effect of an aerobic training program on the electrical remodeling of the heart: high-frequency components of the signal-averaged electrocardiogram are predictors of the maximal aerobic power

Increased heart rate variability (HRV) and high-frequency content of the terminal region of the ventricular activation of signal-averaged ECG (SAECG) have been reported in athletes. The present study investigates HRV and SAECG parameters as predictors of maximal aerobic power (VO2max) in athletes. HRV, SAECG and VO2max were determined in 18 high-performance long-distance (25 ± 6 years; 17 males) runners 24 h after a training session. Clinical visits, ECG and VO2max determination were scheduled for all athletes during thew training period. A group of 18 untrained healthy volunteers matched for age, gender, and body surface area was included as controls. SAECG was acquired in the resting supine position for 15 min and processed to extract average RR interval (Mean-RR) and root mean squared standard deviation (RMSSD) of the difference of two consecutive normal RR intervals. SAECG variables analyzed in the vector magnitude with 40-250 Hz band-pass bi-directional filtering were: total and 40-æV terminal (LAS40) duration of ventricular activation, RMS voltage of total (RMST) and of the 40-ms terminal region of ventricular activation. Linear and multivariate stepwise logistic regressions oriented by inter-group comparisons were adjusted in significant variables in order to predict VO2max, with a P < 0.05 considered to be significant. VO2max correlated significantly (P < 0.05) with RMST (r = 0.77), Mean-RR (r = 0.62), RMSSD (r = 0.47), and LAS40 (r = -0.39). RMST was the independent predictor of VO2max. In athletes, HRV and high-frequency components of the SAECG correlate with VO2max and the high-frequency content of SAECG is an independent predictor of VO2max.

Comparative Study of Signal-Averaged Electrocardiogram between Time Domain Analysis and Spectral Turbulence Analysis by 24-hr Holter Monitoring / 대한내과학회지

OBJECTIVES: Signal-averaged electrocardiography (SAECG) has been found to be a useful noninvasive technique for identifying patients at risk for life-threatening ventricular tachycardia. Delayed and fragmented activation of abnormal myocardial tissues causes the occurrence of high frequency low amplitude (HFLA) electocardiographic signals or late potentials. Generally, there are two methods in analyzing signal-averaged electrocardiography. Late potentials in the time domain analysis do not provide sufficient diagnostic power with regard to life-threatening Ventricular tachycardia. Buckingham et al. (1989) reported a time-domain sensitivity of 62%, a specificity of 75%. Spectral turbulence analysis (STA) of the signal-averaged ECG is the most recent frequency domain technique to improve the time domain sensitivity and specificity. So, We designed the study to compare the efficacy of Time Domain Analysis and Spectral Turbulence Analysis among five groups (Normal control, QRS widening, Postmyocardial infarction, Frequent VPC's with group beats, Nonsustained ventricular tachycardia). METHODS: 88 patients were selected from the patients who had been admitted between January 1994 and October l994, at National Medical Center. Patients were divided into five groups, which were respectively, Group A: Normal control group (n=33), Group B: QRS widening group (n=14), Group C: Postmyocardial infarction group (n=10), Group D: Frequent VPC's with group beats (n=22), Group E: Nonsustained VT group (n=9). We compared Spectral Turbulence Analysis and Time Domain Analysis of Signal-Averaged Electrocardiogram by 24 hours-Holter monitoring. RESULTS: 1) In normal control group(Group A), 9.1%(3 patients) were positive by Time Domain Analysis, but, all were negative by Spectral Turbulence Analysis. 2) In QRS widening group (Group B), 71.4%(10 patients) were positive by Time Domain Analysis, but, all were negative by Spectral Turbulence Analysis. 3) In postmyocardial infarction group (Group C), 309o were positive by Time Domain Analysis, and 10% were positive by Spectral Turbulence Analysis. 4) In frequent VPC's group (Group D), 22.7% (5 patients) were positive by Time Domain Analysis, and, 4.5%(1 patient) was positive by Spectral Tur-bulence Analysis. 5) In Nonsustained VT group (Group E), 33.3% (3 patients) were positive by Time Domain Analysis, and 11.1% (1 patient) was positive by Spectral Turbulence Analysis. CONCLUSIONS: In Time Domain Analysis, abnormal results were presented at Group R (QRS widening group) by 71.4%, which was markedly higher than other groups. But, in Spectral Turbulence Analysis, abnormal results were not presented at Group A and Group B. In Group A and Group B, Spectral Turbulence Analysis shows less false positive results than Time Domain Analysis.

Signal Averaged Electrocardiography Using Holter Tape in Patients without Heart Disease

BACKGROUND: Ventrlcular tachyarrhythmias are major cause of sudden cardiac death in patients after myocardial infarction and their accurate detection seems to be important in prevention of sudden cardiac death. Clinical findings, treasmill test, holter monitoring and coronary angiography have been used to search for high risk group in sudden cardiac death. Recently electrographysiologic stimulation has been to this, but it is not practical, because of high cost and invasiveness. Signal averaged electrocardiogram(SAECG) may be helpful in prediction of high risk group in sudden cardiac death. So we try to know the values of SAECG in Korean patients without heart disease. RESULTS: 1) The mean value and standard deviation of Time domain analysis is as follows ; fQRS : 106.8+/-12.3ms, RMS : 36.2+/-21.5(micro)V, LAS : 27.2+/-8.1ms. 2) The mean value and standard deviation of Spectral turbulence analysis is a follows ; LSCR : 58.6+/-3.9, ISCM : 95.2+/-0.8, ISCSD : 71.8+/-15.7, SE : 6.9+/-1.8. CONCLUSION: There was no significant difference between male and female. Time domain analysis shows significant differences among each hour but spectral turbulence analysis did not. Spectral turbulence analysis shows high specificity.