Endocardial and epicardial radiofrequency ablation of ventricular tachycardia associated with dilated cardiomyopathy
The importance of low-voltage scars
Kyoko Soejima, MD*,*,
William G. Stevenson, MD*,
John L. Sapp, MD*,
Andrew P. Selwyn, MD*,
Gregory Couper, MD and
Laurence M. Epstein, MD*
* Cardiovascular Division, Department of Internal Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
Division of Cardiac Surgery, Brigham and Women's Hospital, Boston, Massachusetts, USA
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Figure 1 Flow diagram of the acute results of the endocardial and epicardial ablation. pts = patients; rf = radiofrequency.
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Figure 2 (A) Voltage map of the endocardial surface of the left ventricle (LV) from Patient 7. An extensive low-voltage area is present in the LV outflow area. (B) Two morphologies of ventricular tachycardia (VT).
(C) Pace mapping at sites 1, 2, and 3 labeled in (A) is shown. A good pace match for VT1 is observed at sites 2 and 3, and a long S-QRS delay (200 ms), consistent with slow conduction away from the pacing site, is observed during pace mapping at site 1. A series of radiofrequency lesions (red circles) across this region from the aortic annulus to the dense scar above the mitral annulus abolished both VTs.
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Figure 3 (A) An endocardial activation sequence map of the left ventricle (LV) from Patient 22. A large area of earliest endocardial activation at the mid-anterior LV (red) suggests the mechanism of the tachycardia being of focal origin; however, the ventricular tachycardia (VT) could be entrained. Radiofrequency (RF) applications at the earliest endocardial sites failed to abolish VT. (B) An epicardial activation sequence map of the same VT as in (A). The activation sequence is consistent with a large re-entry circuit. Sites with green tags are close to the phrenic nerve, as the pacing at these sites produced phrenic nerve stimulation. (C) The epicardial voltage map. Normal voltage (>1.5 mV) tissue is purple. A large area of low-voltage scar is shown. Radiofrequency ablation in the isthmus created by the dense, unexcitable scars (tagged as gray) was not performed owing to proximity to the phrenic nerve (green tags). A series of RF applications along the inner loop sites over the right ventricle did not terminate VT. Additional RF applications from the dense scar to the normal voltage area near the exit over the LV terminated VT. A series of RF applications near the exit was made from the gray area to the normal voltage area, which terminated and abolished inducible VT, but was limited by proximity to the left anterior descending coronary artery (LAD). Ventricular tachycardia recurred 27 days later, likely as a result of the healing of these lesions.
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Figure 4 The surface area (y axis) of the low-voltage (<1.5 mV) endocardial (white bars) and epicardial (black bars) scars in patients with myocardial re-entry. Patient numbers correspond to the patient designations in Table 1.
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Figure 5 For each of the 28 patients the monthly frequency of ventricular tachycardia (VT) episodes (y axis) is shown for the period before (pre) and for the following time intervals: one month after ablation, from two to three months after ablation, and from four to six months after ablation. M = month.
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