Ventricular Tachycardia Originating from the Epicardium Identified by Intracoronary Mapping Using a PTCA Guidewire

Real-time assessment of myocardial viability in the catheterization laboratory using the intracoronary electrograms recorded by the PTCA guidewire in patients with left ventricular dysfunction: comparison with delayed-enhancement magnetic resonance imaging

OBJECTIVES

This study aimed to determine whether the intracoronary electrograms (IC-EGMs) recorded using a standard percutaneous coronary intervention guidewire could provide myocardial viability information.

BACKGROUND

The revascularization of dysfunctional but viable myocardium may confer prognostic benefits compared with medical therapy in patients with post-ischemic heart failure. However, knowledge of myocardial viability is often unavailable at the time of the procedure.

METHODS

The peak-to-peak voltage of 317 IC-EGMs recordings from 25 patients with a previous myocardial infarction and systolic dysfunction were matched with corresponding delayed-enhancement magnetic resonance imaging sites using a 17-segment model of the left ventricle.

RESULTS

Sixty-seven recordings were obtained from segments classified as complete scar on delayed-enhancement magnetic resonance imaging (group A), 162 from partially viable segments (group B), and 88 from fully viable segments (group C). Three high-pass (HP) filters (0.5, 30, and 100 Hz) were applied to the signals to modulate their spatial resolution. For all filters, the peak-to-peak voltage significantly decreased from group C to group B to group A (p < 0.001 for all comparisons). When receiver-operating characteristic analysis was used to compare nonviable (group A) with viable (group B + C) segments, the optimal discriminating voltages were 4.6, 2.2, and 0.78 mV for, respectively, HP-0.5, HP-30, and HP-100 filters, with a sensitivity of 92%, 94%, and 99% and a specificity of 70%, 79%, and 69%.

CONCLUSIONS

The amplitude of the IC-EGMs discriminates viable from nonviable left ventricular segments. Because this technique is simple and inexpensive and provides real-time results, it is potentially useful to aid decision making in the catheterization laboratory.

Intra-coronary guidewire mapping–A novel technique to guide ablation of human ventricular tachycardia

HYPOTHESIS

Endocardial catheter ablation of ventricular tachycardia (VT) may fail if originating from epicardial or intramural locations. We hypothesized that mapping could be achieved using an angioplasty guidewire in the coronary circulation, to guide trans-coronary ablation.

METHODS AND RESULTS

Six patients (2 male), 64 +/- 14 years and previously unsuccessful endocardial VT ablation were studied. Using ECG and existing endocardial mapping data, a coronary artery supplying the predicted VT origin was selected. A 0.014-in angioplasty guidewire was advanced into branches of the artery and connected to an amplifier to record unipolar signals against an indifferent electrode within the inferior vena cava. An uninflated angioplasty balloon was advanced over the wire such that only the distal 5 mm was used for mapping. One VT per patient was mapped (CL 348 +/- 102.1 ms). Diastolic potentials were recorded from all (77.7 +/- 43.8 ms pre-QRS onset) and concealed entrainment demonstrated in 3. Pacemapping during sinus rhythm was used in the remainder due to failure of entrainment (n = 2) or degeneration to VF (n = 1). Following branch identification, cold saline injection causing VT termination was used for further confirmation. Five VTs were ablated using intra-coronary ethanol injection via the central lumen of the inflated over the wire balloon. The other was ablated using radiofrequency energy in a coronary vein adjacent to the target artery, which was too small for an angioplasty balloon. No complications or recurrence of ablated VT was seen over 19 +/- 17 months of follow up.

CONCLUSIONS

Intracoronary guidewire mapping is a novel method of electrophysiological epicardial mapping to help guide trans-coronary VT ablation.