Click on image to view larger version.

Figure 5 Two intracardiac electrograms that were recorded of a sinus beat and the clinical ventricular arrhythmia at the successful ablation sites in two patients. (A) Earliest ventricular activation precedes onset of the QRS complex by –47 ms in a 39-year-old man (Patient #16) with ventricular tachycardia (VT) originating within the pulmonary artery. The presystolic bipolar potential precedes the unipolar potential by –27 ms, and atrial potentials can be clearly recognized from the mapping catheter (arrow). The amplitude of local ventricular bipolar potential is 0.65 mV. (B) Earliest ventricular activation precedes onset of the QRS complex by –48 ms in a 60-year-old woman with VT originating from the endocardial right ventricular outflow tract. The timing of the presystolic bipolar potential is nearly equal to the onset of the local unipolar potential. The atrial potential cannot be seen from the mapping catheter (arrow). The amplitude of local ventricular bipolar potential is 3.68 mV. bi = bipolar signal; CS = coronary sinus electrogram; LCC = left coronary cusp electrogram; PA = pulmonary artery electrogram; RV-end-OT = endocardial right ventricular outflow tract electrogram; uni = unipolar signal.