Ventricular tachycardia due to intramural figure eight reentry revealed by computerized three dimensional electrical activation mapping

Laser photoablation of experimental post-infarction ventricular tachycardia guided by three dimensional activation mapping

“…Arterial blood pressure of a femoral artery, surface electrocardiogram (ECG) and body temperature were monitored during experiments (Monitor 90603A, Spacelab, Redmond, WA). The methods of establishing a subacute myocardial infarction canine model, 3-D cardiac mapping and programmed electrical stimulation (PES) have been presented in detail previously [12][13]21]. Briefly, the proximal left anterior descending coronary artery (LAD) was occluded by inflation a percutaneous coronary angioplasty balloon catheter for 2 hours, followed by reperfusion.…”

“…Surface ECG and 240 intramural bipolar electrograms were simultaneously amplified, filtered (band width 0.2 to 300 Hz), multiplexed at a sampling rate of 1 kHz, A/D converted, and saved by a 255-channel computerized cardiac mapping system (Cardiomapp, Arrhythmia Research Technology, Austin, TX) [12][13]21]. Computer derived activation times were assigned based on the maximum amplitude criterion in reference to the onset of the QRS complex in the surface ECG.…”

“…After a stabilization period of 30 minutes, VT was attempted to be induced by PES or burst pacing (EP-2 Clinical Stimulator, Hi-tronics Designs, Budd Lake, NJ) [12][13]. Stimulation was performed at a pulse width of 2-4 milliseconds (ms) and at twice the diastolic threshold current (0.4-1.0 mA).…”

“…Macro-reentrant VT was identified when: 1) there was continuous electrical activity spanning the systolic and diastolic intervals; 2) the site of origination was spatially and temporally adjacent to the site of termination [12][13][14][15][16][17]. Focal VT was identified when the excitation demonstrated radial spread of activation and was spatially and temporally remote from the site of termination [16][17].…”

“…Experimental and clinical studies have revealed that multiple activation patterns of VT are present in healed or healing myocardial infarction hearts [12][13][14][15][16][17]. The abnormal conduction pathway in variable rhythms may be more completely identified by advanced computerized three-dimensional (3-D) cardiac mapping [12][13][16][17]. This method will be helpful in guiding VT ablation.…”