PMC5415666_01
ECG showing spontaneous subtle change in QRS morphology after induction of ventricular tachycardia. The first beat () of tachycardia resembles the clinical VT. The second beat () of tachycardia and the rest of beats have the same pattern but with subtle difference indicating most probably different exit point from the papillary muscle.
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fig1
Spontaneous changes in QRS morphology were observed (Figure 1). 6 mm cryoablation (Freezor MAX 3, Medtronic,
Fluoroscopy showing the position of cryocatheter at anterior papillary muscle in RAO projection.
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fig2
Activation mapping by the cryocatheter revealed that the site of origin was at anterior PM of LV as confirmed by ICE (Figure 2).
(a) Intracardiac electrogram showing bipolar prepotential preceding the surface QRS by 35 milliseconds (arrow) and unipolar QS pattern (asterisk) recorded at the ablation site during ventricular tachycardia. (b) Programmed stimulation during cryoenergy application did not induce ventricular arrhythmia. The noise in the ablation channel (ABL) is due to ice artifact.
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fig3
Purkinje potentials were recorded at the ablation site during sinus rhythm. Prepotential preceding the surface QRS by 35 milliseconds was recorded at the ablation site during VT (Figure 3(a)). During and after the first application, VA could not be induced with and without isoproterenol (Figure 3(b)).
(a) Intracardiac echocardiography showing the tip of the catheter at the anterior side of anterior papillary muscle. (b) Intracardiac echocardiography showing the tip of the catheter at the posterior side of anterior papillary muscle. Ice formation is shown at the tip of cryocatheter during cryoenergy application.
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fig4
Another 2 applications were done at both sides of anterior PM (Figures 4(a) and 4(b)).