Abnormal Sympathetic Innervation of Viable Myocardium and the Substrate of Ventricular Tachycardia After Myocardial Infarction
Tetsuo Sasano, MD*,
M. Roselle Abraham, MD*,
Kuan-Cheng Chang, MD*,
Hiroshi Ashikaga, MD, PhD*,
Kevin J. Mills, BS*,
Daniel P. Holt, BS ,
John Hilton, PhD,
Stephan G. Nekolla, PhD ,
Jun Dong, MD*,
Albert C. Lardo, PhD*,
Henry Halperin, MD*,
Robert F. Dannals, PhD,
Eduardo Marbán, MD* and
Frank M. Bengel, MD,*
* Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
Division of Nuclear Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
Nuklearmedizinische Klinik, Technical University of Munich, Munich, Germany.
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Figure 2 Segmental Analysis of LV Myocardium
With septum and cardiac long axis as anatomic landmarks, data are assigned to 9 myocardial segments in positron emission tomography (A) and CARTO (Biosense-Webster Inc., Diamond Bar, California) electroanatomical mapping (B). LA = long axis; LV = left ventricle; RV = right ventricle; SA = short axis; other abbreviations as in Figure 1.
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Figure 3 Electrophysiological Characterization of Inducible VT in a Representative Animal
(A) A 12-lead surface electrocardiogram during ventricular tachycardia (VT) shows a superior axis and right bundle branch block pattern, which is compatible with distal anterior origin in the pig heart. (B) A 64-polar endocardial basket catheter indicates the earliest endocardial VT activation site (arrow). The corresponding electrode on the basket catheter, as identified fluoroscopically, is marked by a circle and indicates a distal anterior location.
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Figure 4 Regional Results of EPS, MRI, and PET
Regional results of EPS (A), MRI (B), and PET (C) in the 9 myocardial segments described in Figure 2. Shown are mean ± SD of all animals, except for site of ventricular tachycardia (VT) inducibility, which is shown as an absolute number. For each variable except site of VT, values in segments were compared with each other with analysis of variance, assuming independency of segments. Symbols indicate that the respective segment, highlighted in orange, differed significantly from a large number of other segments (*8, 7, and 6, respectively) after a Bonferroni-corrected post hoc t test, with a p value of 0.0014 to define significance after adjustment for multiple comparisons. ED = end-diastolic; EPI = [11C]-epinephrine; EPS = electrophysiological studies; MRI = magnetic resonance imaging; PET = positron emission tomography; VT = ventricular tachycardia.
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Figure 5 PET Defect Sizes in Animals With and Without Inducible VT
Defects are measured in percentage of left ventricular myocardium, which shows tracer retention below 2.5 SDs from the mean of healthy control animals. PET = positron emission tomography; VT = ventricular tachycardia.
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Figure 6 Study Results in a Representative Animal With Inducible VT
Positron emission tomography polarmaps (left) show regional distribution of [13N]-ammonia and [11C]-epinephrine retention (top), along with perfusion (white) and innervation defects (blue; bottom). Segmental analysis (bottom right) shows that innervation defect exceeds perfusion defect predominantly in the distal anterior wall segment, highlighted in yellow. Three-dimensional electroanatomical maps, depicted in anterior view on top right, show reduced bipolar endocardial voltage in apex and distal septum/anterior wall. Propagation maps show earliest activation of VT in the infarct borderzone in the distal anterior wall (red arrow). Abbreviations as in Figures 1, 2, and 4.
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Figure 7 Correlation of Segmental Results of PET and Electroanatomic Mapping
Shown is a plot for average values of reduced voltage versus EPI retention abnormality in 9 myocardial segments. Standard deviations for each segment for both variables are indicated by horizontal/vertical lines originating from each data point. Abbreviations as in Figure 4.
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