The critical isthmus sites of ischemic ventricular tachycardia are in zones of tissue heterogeneity, visualized by magnetic resonance imaging

Estner, Heidi L.; Zviman, M. Muz; Herzka, Dan; Miller, Frank; Castro, Valeria; Nazarian, Saman; Ashikaga, Hiroshi; Dori, Yoav; Berger, Ronald D.; Calkins, Hugh; Lardo, Albert C.; Halperin, Henry R.

doi:10.1016/j.hrthm.2011.07.027

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Volume 8, Issue 12 , Pages 1942-1949, December 2011

The critical isthmus sites of ischemic ventricular tachycardia are in zones of tissue heterogeneity, visualized by magnetic resonance imaging

Presented in part at the American Heart Association Scientific Session 2009 in Orlando, Florida.

Heidi L. Estner, MD
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Address reprint requests and correspondence: Dr. Heidi L. Estner, Division of Cardiology, Johns Hopkins University School of Medicine, 720 Rutland Avenue, Traylor 903, Baltimore, MD 20215
M. Muz Zviman, PhD
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
Dan Herzka, PhD
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
Frank Miller
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
Valeria Castro
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
Saman Nazarian, MD, PhD
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
Hiroshi Ashikaga, MD, PhD
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
Yoav Dori, MD, PhD
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
Ronald D. Berger, MD, PhD
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
Hugh Calkins, MD, PhD
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
Albert C. Lardo, MD, PhD
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
Henry R. Halperin, MD, MA
- Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland

Received 8 February 2011; accepted 19 July 2011. published online 27 July 2011.

Background

A need exists to devolop alternative approaches to VT ablation that provide an improved delineation of the arrhythmogenic substrate.

Objective

The aim of this study was to evaluate the hypotheses that: (1) the heterogeneous zone (HZ, a mixture of normal-appearing tissue and scar) in magnetic resonance imaging (MRI) contains the critical isthmus(es) for ventricular tachycardia (VT), (2) successful ablation of VT would include ablation in the HZ, and (3) inadequate ablation of HZ allows for VT recurrence.

Methods

MRI and an electrophysiology study (EP) were performed in a model of chronic myocardial infarction in 17 pigs. In animals that were inducible for VT, ablations were done guided by standard EP criteria and blinded to the MRI. After ablation, electroanatomic mapping results were co-registered with MRI.

Results

In 8 animals, 22 sustained monomorphic VTs were generated. The HZ was substantially larger in inducible (n = 8) compared with noninducible animals (n = 9) [25% ± 10% vs 13% ± 5% of total scar, respectively, P = .007]. Acutely, all targeted VTs were successfully ablated, and postprocedure analysis showed that at least 1 ablation was in the HZ in each animal. In 5 animals, a second EP and MRI were performed 1 week after ablation. Three animals had inducible VTs, and MRI showed that the HZ had not been completely ablated. In contrast, the 2 animals without inducible VT revealed no remaining HZ.

Conclusion

These findings show that MRI can define an HZ and determine the location of ablated lesions. The HZ may be a promising ablation target to cure ischemic VTs. Remnants of HZ after ablation may be the substrate for clinical relapses.

Keywords: Ischemic ventricular tachycardia, Catheter ablation, MRI

Abbreviations: 3D, three-dimensional, CT, computed tomography, EP, electrophysiology, HZ, heterogeneous zone, LV, left ventricular, MI, myocardial infarction, MRI, magnetic resonance imaging, RF, radiofrequency, VT, ventricular tachycardia

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This work has received funding from the European Union Seventh Framework Program (FP7/2007-2013) under grant agreement 219384; National Heart, Lung, and Blood Institute R01 HL64795 and R01 HL94610; and the Donald W. Reynolds Foundation.

PII: S1547-5271(11)00847-2

doi:10.1016/j.hrthm.2011.07.027

« Previous Next »Heart Rhythm
Volume 8, Issue 12 , Pages 1942-1949, December 2011

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