J Interv Card Electrophysiol (2014) 39:77–85 DOI 10.1007/s10840-013-9850-2
Findings on magnetic resonance imaging of fascicular ventricular tachycardia Bernhard Herkommer & Michael Fiek & Christopher Reithmann
Received: 27 July 2013 / Accepted: 10 October 2013 / Published online: 29 November 2013 # Springer Science+Business Media New York 2013
Abstract Background Idiopathic left ventricular tachycardia (ILVT) with right bundle branch block and left axis deviation originates from the left posterior fascicle—Purkinje fiber network. Scar-related ventricular tachycardias (VTs) with Purkinje fibers as a part of the reentry circuit have also been described in patients with structural heart disease. Methods and results Nine patients with fascicular VT (left posterior, n = 8; left anterior, n = 1) with preserved left ventricular ejection fraction (60±10 %) underwent cardiac magnetic resonance imaging (MRI) including functional analysis and delayed enhancement magnetic resonance imaging (DE-MRI). No definite structural abnormalities were detected by DE-MRI in four patients. DE-MRI revealed unifocal or multifocal areas of fibrosis or scar in three patients corresponding to the regions where typical Purkinje potentials guided successful ablation of the sustained fascicular VT. A false tendon extending from the free wall to the septum was found in one patient. Moderate reduction of left ventricular ejection fraction associated with septal or multifocal left ventricular fibrosis was detected in two patients with ventricular bigeminy originating from the left posterior fascicle. During the follow-up of 29 ± 22 months after successful catheter ablation in the nine patients, one patient with septal fibrosis detected by DE-MRI had VT recurrence and received an implantable cardioverter defibrillator. Conclusion Detection of local areas of fibrosis or scar by DEMRI may help to distinguish idiopathic fascicular tachycardia B. Herkommer : M. Fiek : C. Reithmann (*) Medizinische Klinik I, Klinikum München Pasing, Akademisches Lehrkrankenhaus der Ludwig-Maximilians-Universität München, Steinerweg 5, 81241 München, Germany e-mail: [email protected]
from scar-related fascicular VT in patients with preserved left ventricular function. Keywords Ventricular tachycardia . Left bundle fascicle . Cardiac magnetic resonance imaging . Delayed enhancement
1 Introduction The His Purkinje system can be involved in the reentry circuit of sustained monomorphic ventricular tachycardia (VT) in patients without or with structural heart disease. Idiopathic fascicular left ventricular tachycardia (ILVT) is a distinct clinical entity in patients without structural heart disease which is characterized by a right bundle branch block morphology with left axis deviation [1–3]. The tachycardia usually originates from the region of the posterior fascicle of the left bundle. A false tendon extending from the posterior inferior left ventricle to the septum was suggested to be responsible for this unique arrhythmia in patients with ILVT [4]. VTs with a relatively narrow QRS mimicking ILVT and the Purkinje system of the left posterior fascicle as a part of the reentry circuit have been described in patients postmyocardial infarction [5] and in patients with nonischemic cardiomyopathy [6]. Magnetic resonance assessment of scar tissue and fibrosis is now established as a method to define the substrate of monomorphic VT in patients with ischemic [7] and nonischemic cardiomyopathy [8, 9]. The present study was performed to evaluate the role of delayed enhancement magnetic resonance imaging (DE-MRI) to identify a possible ventricular arrhythmia substrate in patients with fascicular tachycardia. We hypothesized that DE-MRI may facilitate the differentiation between ILVT and scar-related fascicular VT associated with a higher risk of VT recurrence.
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2 Methods 2.1 Patients Between 2006 and April 2013, 19 patients with fascicular VT underwent electrophysiologic study and catheter ablation in our institution. Among them, 17 had a left posterior fascicular VT with right bundle branch block and left axis deviation and 2 had a left anterior VT with right bundle branch block and right axis deviation. Sustained monomorphic VT was the clinical arrhythmia in 17 patients. Ventricular bigeminy associated with nonsustained and sustained VT originating from the left posterior fascicle was the predominant clinical arrhythmia in two patients. Coronary angiography was performed in all patients. The subjects of the DE-MRI study were nine patients (five males and four females, 55±15 years) with recurrent symptomatic fascicular ventricular arrhythmias (left posterior fascicular tachycardia in eight patients and left anterior fascicular tachycardia in one patient). A 12-lead ECG showing the clinical VT was available in all patients. Echocardiographic evaluation including the presence or absence of a false tendon was performed in all patients. 2.2 Evidence of participation of the posterior or anterior fascicle of the left bundle Diagnostic criteria for participation of the posterior or anterior bundle of the left fascicle or the surrounding Purkinje network have recently been described in detail [6]. Participation of the left bundle Purkinje system was defined as a potential of the posterior or anterior fascicle of the left bundle or Purkinje potential closely preceding the VT QRS. The presence of a left bundle fascicle or Purkinje fiber in the VT reentry circuit was validated by a left bundle potential or Purkinje potential during sinus rhythm at the same site and termination of the VT by ablation at this site during the VT. Spontaneous variations in VV interval were preceded by similar changes in left bundle fascicle potential intervals or Purkinje potential intervals. 2.3 Cardiac MRI The cardiac MRI studies were performed on a 3T magnetic resonance imaging scanner (Philips Achieva, Best, Netherlands) with a five-element phased array coil placed over the chest of patients in the supine position. Images were acquired with electrocardiographic gating during breath-holds. Dynamic short- and long-axis images of the heart were acquired using a segmented k-space, steady-state free-precession pulse sequence (30 phases, 1.4×1.4 mm in-plane resolution, 8-mm slice thickness). Ten minutes after administration of 0.15 mmol/kg of intravenous gadolinium DTPA (GadovistR, 1 mmol/ml), three-dimensional delayed enhancement imaging was performed using a 3D inversion recovery sequence (repetition
J Interv Card Electrophysiol (2014) 39:77–85
time 6.7 ms, echo time 3.2 ms, in-plane spatial resolution 1.4× 2.2 mm, slice thickness 8 mm) in the short- and long-axis of the left ventricle. The inversion time (200 to 350 ms) was optimized to null the normal myocardium by the use of a look locker sequence. The DE-MRIs were reviewed for the presence or absence of delayed enhancement by one observer blinded to the results of mapping and ablation. End-diastolic and endsystolic volumes and left ventricular (LV) ejection fraction were determined by MRI. 2.4 Electrophysiologic study After giving informed consent including the risk of intraprocedural fascicular block or complete atrioventricular block, all patients underwent electrophysiologic study. Catheters were introduced to the right ventricular (RV) apex and the His bundle region. LV mapping for fascicular tachycardia was performed retrogradely or trans-septally (in one patient) with a steerable catheter with a 4-mm electrode tip (Cordis Webster Inc., Baldwin Park, CA, USA). Activation mapping during fascicular tachycardia was followed by a detailed mapping of the Purkinje network of the posterior or anterior left bundle fascicle. The 3D mapping system Ensite NavX™ (St. Jude Medical, St. Paul, MN, USA) was used to create a voltage map during sinus rhythm in one patient. Detailed mapping criteria and determination of the targets for ablation have been described in detail [6, 10]. The stimulation protocol consisted of a programmed ventricular stimulation from the RV apex and the RV outflow tract at four cycle lengths with up to three extrastimuli. If the VT was not inducible by endocardial stimulation, stimulation was repeated under orciprenaline stimulation. Fragmented electrograms during sinus rhythm were defined as intracardiac bipolar multicomponent potentials with a duration >60 ms and an amplitude
Findings on magnetic resonance imaging of fascicular ventricular tachycardia Bernhard Herkommer & Michael Fiek & Christopher Reithmann
Received: 27 July 2013 / Accepted: 10 October 2013 / Published online: 29 November 2013 # Springer Science+Business Media New York 2013
Abstract Background Idiopathic left ventricular tachycardia (ILVT) with right bundle branch block and left axis deviation originates from the left posterior fascicle—Purkinje fiber network. Scar-related ventricular tachycardias (VTs) with Purkinje fibers as a part of the reentry circuit have also been described in patients with structural heart disease. Methods and results Nine patients with fascicular VT (left posterior, n = 8; left anterior, n = 1) with preserved left ventricular ejection fraction (60±10 %) underwent cardiac magnetic resonance imaging (MRI) including functional analysis and delayed enhancement magnetic resonance imaging (DE-MRI). No definite structural abnormalities were detected by DE-MRI in four patients. DE-MRI revealed unifocal or multifocal areas of fibrosis or scar in three patients corresponding to the regions where typical Purkinje potentials guided successful ablation of the sustained fascicular VT. A false tendon extending from the free wall to the septum was found in one patient. Moderate reduction of left ventricular ejection fraction associated with septal or multifocal left ventricular fibrosis was detected in two patients with ventricular bigeminy originating from the left posterior fascicle. During the follow-up of 29 ± 22 months after successful catheter ablation in the nine patients, one patient with septal fibrosis detected by DE-MRI had VT recurrence and received an implantable cardioverter defibrillator. Conclusion Detection of local areas of fibrosis or scar by DEMRI may help to distinguish idiopathic fascicular tachycardia B. Herkommer : M. Fiek : C. Reithmann (*) Medizinische Klinik I, Klinikum München Pasing, Akademisches Lehrkrankenhaus der Ludwig-Maximilians-Universität München, Steinerweg 5, 81241 München, Germany e-mail: [email protected]
from scar-related fascicular VT in patients with preserved left ventricular function. Keywords Ventricular tachycardia . Left bundle fascicle . Cardiac magnetic resonance imaging . Delayed enhancement
1 Introduction The His Purkinje system can be involved in the reentry circuit of sustained monomorphic ventricular tachycardia (VT) in patients without or with structural heart disease. Idiopathic fascicular left ventricular tachycardia (ILVT) is a distinct clinical entity in patients without structural heart disease which is characterized by a right bundle branch block morphology with left axis deviation [1–3]. The tachycardia usually originates from the region of the posterior fascicle of the left bundle. A false tendon extending from the posterior inferior left ventricle to the septum was suggested to be responsible for this unique arrhythmia in patients with ILVT [4]. VTs with a relatively narrow QRS mimicking ILVT and the Purkinje system of the left posterior fascicle as a part of the reentry circuit have been described in patients postmyocardial infarction [5] and in patients with nonischemic cardiomyopathy [6]. Magnetic resonance assessment of scar tissue and fibrosis is now established as a method to define the substrate of monomorphic VT in patients with ischemic [7] and nonischemic cardiomyopathy [8, 9]. The present study was performed to evaluate the role of delayed enhancement magnetic resonance imaging (DE-MRI) to identify a possible ventricular arrhythmia substrate in patients with fascicular tachycardia. We hypothesized that DE-MRI may facilitate the differentiation between ILVT and scar-related fascicular VT associated with a higher risk of VT recurrence.
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2 Methods 2.1 Patients Between 2006 and April 2013, 19 patients with fascicular VT underwent electrophysiologic study and catheter ablation in our institution. Among them, 17 had a left posterior fascicular VT with right bundle branch block and left axis deviation and 2 had a left anterior VT with right bundle branch block and right axis deviation. Sustained monomorphic VT was the clinical arrhythmia in 17 patients. Ventricular bigeminy associated with nonsustained and sustained VT originating from the left posterior fascicle was the predominant clinical arrhythmia in two patients. Coronary angiography was performed in all patients. The subjects of the DE-MRI study were nine patients (five males and four females, 55±15 years) with recurrent symptomatic fascicular ventricular arrhythmias (left posterior fascicular tachycardia in eight patients and left anterior fascicular tachycardia in one patient). A 12-lead ECG showing the clinical VT was available in all patients. Echocardiographic evaluation including the presence or absence of a false tendon was performed in all patients. 2.2 Evidence of participation of the posterior or anterior fascicle of the left bundle Diagnostic criteria for participation of the posterior or anterior bundle of the left fascicle or the surrounding Purkinje network have recently been described in detail [6]. Participation of the left bundle Purkinje system was defined as a potential of the posterior or anterior fascicle of the left bundle or Purkinje potential closely preceding the VT QRS. The presence of a left bundle fascicle or Purkinje fiber in the VT reentry circuit was validated by a left bundle potential or Purkinje potential during sinus rhythm at the same site and termination of the VT by ablation at this site during the VT. Spontaneous variations in VV interval were preceded by similar changes in left bundle fascicle potential intervals or Purkinje potential intervals. 2.3 Cardiac MRI The cardiac MRI studies were performed on a 3T magnetic resonance imaging scanner (Philips Achieva, Best, Netherlands) with a five-element phased array coil placed over the chest of patients in the supine position. Images were acquired with electrocardiographic gating during breath-holds. Dynamic short- and long-axis images of the heart were acquired using a segmented k-space, steady-state free-precession pulse sequence (30 phases, 1.4×1.4 mm in-plane resolution, 8-mm slice thickness). Ten minutes after administration of 0.15 mmol/kg of intravenous gadolinium DTPA (GadovistR, 1 mmol/ml), three-dimensional delayed enhancement imaging was performed using a 3D inversion recovery sequence (repetition
J Interv Card Electrophysiol (2014) 39:77–85
time 6.7 ms, echo time 3.2 ms, in-plane spatial resolution 1.4× 2.2 mm, slice thickness 8 mm) in the short- and long-axis of the left ventricle. The inversion time (200 to 350 ms) was optimized to null the normal myocardium by the use of a look locker sequence. The DE-MRIs were reviewed for the presence or absence of delayed enhancement by one observer blinded to the results of mapping and ablation. End-diastolic and endsystolic volumes and left ventricular (LV) ejection fraction were determined by MRI. 2.4 Electrophysiologic study After giving informed consent including the risk of intraprocedural fascicular block or complete atrioventricular block, all patients underwent electrophysiologic study. Catheters were introduced to the right ventricular (RV) apex and the His bundle region. LV mapping for fascicular tachycardia was performed retrogradely or trans-septally (in one patient) with a steerable catheter with a 4-mm electrode tip (Cordis Webster Inc., Baldwin Park, CA, USA). Activation mapping during fascicular tachycardia was followed by a detailed mapping of the Purkinje network of the posterior or anterior left bundle fascicle. The 3D mapping system Ensite NavX™ (St. Jude Medical, St. Paul, MN, USA) was used to create a voltage map during sinus rhythm in one patient. Detailed mapping criteria and determination of the targets for ablation have been described in detail [6, 10]. The stimulation protocol consisted of a programmed ventricular stimulation from the RV apex and the RV outflow tract at four cycle lengths with up to three extrastimuli. If the VT was not inducible by endocardial stimulation, stimulation was repeated under orciprenaline stimulation. Fragmented electrograms during sinus rhythm were defined as intracardiac bipolar multicomponent potentials with a duration >60 ms and an amplitude
