[Effect of pharmacologic blockade of the autonomic system on time domain parameters of atrial and ventricular signal-averaged ECG in subjects with mitral valve prolapse].

The aim of this study was evaluation of pharmacologic autonomic blockade on time-domain parameters of atrial (ASAECG) and ventricular signal-averaged ECG (SAECG) in patients with mitral valve prolapse syndrome (MVP) regarded 20 subjects with MVP (mean age 34.9 +/- 5.3) (group I) were studied as well as a control group consisting of 20 healthy subjects (mean age 37.5 +/- 4.6) (group II). Initially, two dimensional echocardiography with color doppler examination, ambulatory Holter monitoring, multistage treadmill exercise test, transoesophageal pacing (TEP), recording of ASAECG and SAECG were made. Subsequently, pharmacologic autonomic system blockade was done by using intravenously propranolol (0.1 mg/kg) and atropine (0.02 mg/kg). The following time-domain parameters of ASAECG were calculated: the root mean square voltage for the last 10, 20, 30 ms of filtered P-wave (RMS 10, 20, 30) and time duration of filtered P-wave (PWD). Moreover, the following parameters of SAECG were analyzed: the root mean square voltage of the signals in the last 40 and 50 ms of the filtered QRS (RMS 40, 50), the total time duration of QRS(t-QRS) and the duration of low amplitude signals < 40 microV (LPD). The autonomic blockade did not change significantly the obtained values of RMS 10, 20, 30 in subjects with MVP as follows: RMS 10 from 5.5 +/- 2.9 microV to 6.3 +/- 2.4 microV, RMS 20 from 8 +/- 3.7 microV to 8.5 +/- 2.4 microV and RMS30 from 10.2 +/- 4.9 microV to 10.3 +/- 3.3 microV. On the other hand, also the values of RMS 10 did not change statistically significant after blockade in control group (from 5.8 +/- 2.2 microV to 5.6 +/- 1.7 microV, p > 0.05), but the values of RMS20 i RMS30 increased significantly in this group, respectively from 7 +/- 3.1 microV to 8.3 +/- 3 microV (p < 0.02) and from 8.4 +/- 3.1 microV to 10.1 +/- 3.6 microV, (p < 0.05). The values of PWD have changed differently in the examined groups being under the influence of the autonomic blockade: in group I decreased from 119 +/- 12 ms to 114 +/- 28 ms (p > 0.05), whereas in group II increased from 110 +/- 13 ms to 116 +/- 9 ms (p < 0.02).(ABSTRACT TRUNCATED AT 400 WORDS)