PMC4008241_01
Twelve lead ECG showing ventricular bigeminy, doublet PVC's with an RBBB configuration with an RS interval of >100 msec in the precordial leads, and a pseudodelta wave configuration suggesting an epicardial origin of the ventricular ectopy.
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fig1
PVC with an RBBB morphology (Figure 1). Echocardiography showed a dilated left atrium and a dilated left ventricle with decreased LV function. Preablation MRI images were of poor quality due to frequent PVCs and nonsustained VTs.
Fluoroscopic image showing the ablation catheters at the site of earliest activation endocardially and epicardially. The tip of the ablation catheters was located at the apicolateral side of the left ventricle. Ablation endocardially resulted in temporary elimination of the ectopy. Epicardially RF energy delivery was associated with phrenic nerve stimulation.
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fig2
A cooled tip quadripolar ablation catheter (Biosense Webster) was inserted into the pericardial space and manipulated easily to areas corresponding to the endocardial sites at which ablation had previously failed (Figure 2).
Multielectrode high density mapping was performed using a rectangular grid electrode harboring 64 electrode terminals arranged in an 8 x 8 matrix (interelectrode distance 5 mm). The electrode was positioned over the area where the origin of the tachycardia was expected. The earliest site of epicardial activation was located at the apicolateral side of the left ventricle. The numbers on the left side of the unipolar electrograms refer to the grid electrodes (a). The unipolar electrogram recorded at the earliest activated site was initially negative, suggesting that activation spread from this site. Isochronal maps depict the centrifugal activation pattern of the ectopic beats (b and c). Electrograms at sites adjacent to the earliest activated site were fractionated, suggesting discontinuous conduction (d). See text for details.
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fig3
Multielectrode high density mapping was performed using a rectangular grid electrode harboring 64 electrode terminals arranged in an 8 x 8 matrix (interelectrode distance 5 mm, Figures 3(a) and 3(b). The site of earliest epicardial activation was located at the apicolateral side of the left ventricle (Figures 3(a) and 3(b)). The unipolar electrogram recorded at the earliest activated site was initially negative, indicative for an origin of activation at that site (electrogram in Figure 3(a)). The activation map revealed centrifugal spread of activation from the earliest activated site (Figure 3(c)). Electrograms at sites adjacent to the earliest activated site were fractionated, suggesting discontinuous conduction (Figure 3(d)).
After ablation, a cardiac MRI study was performed. MRI images showed a slightly dilated left ventricle. End diastolic LV volume was 213 mL. End systolic LV volume was 112 mL. Stroke volume was 101 mL, LVEF was 47% and IVSDd was 11 mm. Gadolinium was used to evaluate myocardial perfusion. At the apicolateral side of the LV, a small area with transmural late enhancement was identified.
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fig4
The MRI images (Figure 4) showed a dilated left ventricle.