[Transient myocardial ischemia in patients after myocardial infarction and late cell potentials]. / Przejsciowe niedokrwienie u chorych po zawale miesnia sercowego a pózne potencjaly komorowe.

The role of myocardial ischaemia in the development of late potentials (LP) on the signal-averaged ECG (SAECG) in patients with coronary artery disease (CAD) remains controversial. The aim of the study was to assess the influence of transient, scintigraphically-proven (Tc-99mMI-BI), exercise-induced ischaemia on the presence of LP in 51 pts with angiographically documented CAD. Patients were divided into 2 groups: 26 pts (mean age 53 +/- 7.7) without the history of myocardial infarction (MI) (Group I) and 25 pts (mean age 56.8 +/- 6.4) after MI (Group II). SAECG recording were performed at baseline (A) and during exercise-induced ischaemia (B). The following time-domain parameters of SAECG were analyzed: the root mean square voltage of the last 40 and 50 ms of filtered QRS (RMS40, 50), total time duration of filtered QRS (t0QRS) and time duration potentials < 40 microV (LPD). The ventricular late potentials (LP) were defined as the presence of at least two of the following criteria: tQRS > 114 ms, RMS 40 < 20 mV and LPD > 38 ms. We conclude that transient exercise-induced ischaemia increased the presence of LP in pts with CAD after MI but did not alter the arrhythmogenic substrate for LP in those without the history of MI.

[The effect of intravenously given amiodarone on maintenance of ventricular signal averaged electrocardiogram in patients with ischemic heart disease]. / Wplyw dozylnie podanego amiodaronu na zachowanie sie usrednionego sygnalu komorowego u chorych na chorobe niedokrwienna serca.

Recording of ventricular signal-averaged ECG (VSAE) were carried out in 19 patients suffering from ischemic heart disease before and after intravenously administration of amiodarone using a commercially available machine HIPEC-200 HA device of Aerotel's. The high gain ECG was recorded during basic rhythm with orthogonal Frank leads X, Y, Z. These combined into a vector magnitude and the QRS duration (QRS), the duration of low amplitude signals < 40 microV (LPD) and the root mean square voltage of the signals in the last 40 and 50 ms of the filtered QRS (RMS 40,50) were calculated for VSAE. It was time-domain analysis of VSAE. In frequency domain analysis were calculated the following parameters in range from 40 Hz to 400 Hz in linear scale: area ratio 20-50 Hz/0-20 Hz, peak and magnitude ratio and in logarithmic scale: energy spectrum > -60 dB and decibel drop at 40 Hz. Subsequently amiodarone hydrochloride was given intravenously 5 mg/kg c.c. and again time-domain and frequency domain analysis were done. Data presented are mean +/- standard deviation. Statistical comparisons were performed with paired t-Student test. Significance refers to a p values < 0.05. Time-domain analysis of VSAE didn't show any significant differences after amiodarone injection. During frequency-domain analysis of VSAE statistically significant differences were displayed in Frank lead X and Y for energy spectrum > -60 dB. In Frank lead X decrease of this parameter after amiodarone (from 3322 +/- 1057 dB-Hz to 2628 +/- 733) and in lead Y increase (from 2793 +/- 500 dB-Hz to 3199 +/-938 dB-Hz) was noticed. Our observation have indicated that intravenously application of amiodarone hydrochloride didn't change parameters in time-domain analysis. Statistically significant differences were noticed only during frequency analysis VSAE in logarithmic scale -energy spectrum > -60 dB but only in two leads X and Y.