Body surface potential mapping of QRST changes during and after percutaneous transluminal coronary angioplasty

The present study reports preliminary results on 23 patients undergoing percutaneous transluminal coronary angioplasty (PTCA); 120 lead body surface potential maps (BSPM) were recorded before, during and after balloon inflation. Twelve patients underwent PTCA for LAD coronary disease, 6 for RCA and 4 for LCx; one patient had combined LAD and RCA disease. Instantaneous voltage measurements during the QRST complex were obtained by sampling time-normalized QRS and STT waveforms. In each patient, maps recorded during the various phases of the procedure were compared with the patient´s own baseline map. Also, for each patient, successive maps were compared to group-mean normal maps computed from 159 normal control subjects. In 6 out of 23 patients, maps were also recorded 24 hours after PTCA. In most cases, QRST changes occurred in areas corresponding approximately to the vascular beds of the inflated arteries. In the LAD group, mid-to-late QRS voltage increase accompanied ST elevation in the left anterior and superior torso. In the RCA group, QRS changes were observed in the lower anterior and posterior chest with corresponding ST elevation. Similarly, inflation of the LCx produced QRST changes mostly in the back. In all but 3 subjects, QRST changes were present after the PTCA procedure was completed and in 6 patients with map recordings 24 hours post-PTCA, QRST changes could still be observed