Tissue Tracking Imaging for Identifying the Origin of Idiopathic Ventricular Arrhythmias: A New Role of Cardiac Ultrasound in Electrophysiology

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RACING,and ELECTROPHYSIOLOGY www.ipej.org 155
Journal

Editorial

Tissue Tracking Imaging for Identifying the Origin of
Idiopathic Ventricular Arrhythmias: A New Role of
Cardiac Ultrasound in Electrophysiology

Sunil Roy T.N., MBBS, MD, DM*, Vikram Sankar, MBBS, MD*, Johnson Francis, MBBS,
MD, DM*, Hiroshi Tada, MD^t

*Medical College Calicut, Kerala, India; ^tDivision of Cardiology, Gunma Prefectural
Cardiovascular Center, Maebashi, Gunma Japan.

Address for correspondence: Dr. Sunil Roy T.N, Senior Lecturer in Cardiology, Medical
College Hospital, Calicut, Kerala, India. E mail: [email protected]

Abstract

Several strategies for mapping ventricular outflow tract tachycardia have been reported
as useful indices for differentiating between those originating from the right and the left side.
Recently, tissue tracking imaging (TTI) has been demonstrated as a novel non-invasive modality
for identifying the origin of outflow tract tachycardias. Tissue tracking imaging is an
ultrasonographic technique that measures the myocardial motion amplitude towards the
transducer in each region during systole, identifying regional myocardial displacement on the
basis of myocardial velocities using color Doppler myocardial imaging principles. In this
technique, the origin of the arrhythmia could be recognized as the site where the earliest color-
coded signal (ECCS) appeared on the myocardium at the onset of the systole. In preliminary
studies this modality was found to be useful in differentiating out flow tract ventricular
tachycardias. ECCS was always found below or at the level of the pulmonary valve in all
arrhythmias which could be ablated from the right ventricular outflow tract, while in those
where the origin was above the pulmonary valve could be ablated from the left sinus of valsalva.
These results indicate that TTI can provide detailed and accurate information on the arrhythmia
origin of OT-VT and may be useful for differentiating between an OT-VT originating from the
LV epicardium remote from the LSV and that from the LSV. Newer advances in
echocardiographic technologies like high resolution, high frame rate real time three dimensional
echocardiography with speckle tracking may further improve the precise localization of
arrhythmias in the future.

Keywords: Tissue tracking imaging; Ventricular tachycardia; Earliest color-coded signal;
Myocardial motion amplitude; Speckle tracking

Radiofrequency (RF) catheter ablation has been established as an effective and curative
therapy for ventricular tachycardias (VTs) or symptomatic premature ventricular contractions
(PVCs) originating from the outflow tract (OT-VT/PVCs) in structurally normal hearts.¹ Most
of these arrhythmias have their origin in the septal aspect of the right ventricular outflow tract
(RVOT), but some originate from the free wall of the RVOT, or the endocardium of the left
ventricular outflow tract (LVOT).² Thus OT-VT/PVC can originate from several different

Indian Pacing and Electrophysiology Journal (ISSN 0972-6292), 5(3): 155-159 (2005)

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