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Nonsurgical transthoracic epicardial catheter ablation to treat recurrent ventricular tachycardia occurring late after myocardial infarction

^a Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil

View larger version (116K): [in a new window]   Figure 1 Technique used to insert the mapping and ablation catheter in the pericardial space. The needle used for epidural anesthesia (detailed in the left superior corner) being currently used for transthoracic pericardial puncture, according to the technique described by Kirkorian, to drain epicardial effusions (panel 1). A soft floppy-tip guidewire is introduced into the pericardial space (large arrow), where contrast is also present (black arrows) (panel 2). Then, an 8F introducer is advanced, the guidewire is removed and a quadripolar, 4-mm tip, 7F regular steerable catheter is gently introduced into the pericardial sac to perform epicardial mapping and/or ablation. Panel 3 demonstrates a right anterior oblique view at 60° obtained by fluoroscopy during epicardial mapping procedure. The epicardial catheter (arrow) is manipulated and placed in different locations of the epicardial space (A to F), where epicardial electrograms are obtained. RV = right ventricular apex catheter; CS = coronary sinus; 1 = coronary sinus catheter; 2 = endocardial left ventricular catheter; 3 = right apical endocardial catheter.

View larger version (112K): [in a new window]   Figure 2 Panel 1 shows a contrasted ventriculography in systole at 30° right anterior oblique view in a patient with postinfarction VT. Notice a large inferolateral aneurysm (dotted lines). The epicardial catheter (EPI) positioned in the aneurysmatic area for mapping in the right (RAO) anterior oblique (panel 2) and left (LAO) anterior oblique (panel 3) views at 30° are shown. RV = right endocardial apical catheter; Transeptal = quadripolar catheter inserted in the left basal inferior wall through transeptal puncture due to advanced aortic disease.

View larger version (35K): [in a new window]   Figure 3 Activation mapping of ventricular tachycardia obtained during a transthoracic epicardial ablation procedure. The epicardial electrogram found in EPI precedes the onset of the QRS complex by 100 ms (upper panel) and it was used to guide ablation. Due to a high stimulation threshold, ventricular capture was not obtained during bipolar pacing from the epicardial catheter. At these sites, an epicardial application of RF interrupted VT within 6 s (lower panel) and rendered it noninducible. Electrocardiographic I, II, III, V1, and V6 leads are shown. VTCL = ventricular tachycardia cycle length; RV = right endocardial apical catheter; Epi = the epicardial mapping and ablation catheter; CS = coronary sinus catheter; p = proximal par of electrodes; V = ventricular electrogram; A = atrial electrogram; HR = heart rate; bpm = beats per minute.

View larger version (41K): [in a new window]   Figure 4 Activation mapping of ventricular tachycardia obtained during a transthoracic epicardial ablation procedure. A midiastolic signal found in the epicardial catheter distal bipole (Epi-d) precedes the onset of the QRS complex by 100 ms (upper panel). Application at this site interrupted VT after 1.4 s which could not be reinduced. Abbreviations as in Figure 3. b and 1 = distal par of electrodes; a = proximal par of electrodes.