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A Case Study on Cardiac Imaging in Patientswith Arrhythmogenic Right Ventricular

Dysplasia/Cardiomyopathy—A Comparison between 64-Slice ComputedTomography, Magnetic Resonance Imaging

and Electroanatomical Mapping—

Kei Nishiyama MD, Takahiro Doi MD, Satoshi Shizuta MD, Takayuki Yamamoto MD,Kouji Hanazawa MD, Toru Kita MD PhD, Takeshi Kimura MD PhD

Departments of Cardiovascular Medicine, Kyoto University Graduate School of Medicine

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an uncommontype of cardiomyopathy with fibrofatty tissue replacement. Magnetic resonance imaging(MRI) is a sophisticated method for the diagnosis of ARVD/C. Electroanatomical mappinghas been reported to rapidly provide accurate data that facilitates catheter ablation of VTin ARVD/C. In addition, multislice CT (MSCT) is fast, easy to perform, and has a morereliable image quality. MSCT is considered a clinically valuable, noninvasive tool forassessment of myocardial pathology. However, the relationship between MSCT, cardiac MRIand electroanatomical mapping imaging in patients with ARVD/C is unknown. We reporttwo cases diagnosed as ARVD/C by endomyocardial biopsy. In one case MRI imagingrevealed marked wall thinning and a decrease in wall motion in the inferior wall and basalinterventricular septum of the left ventricle. In another case an electroanatomical map of theRV was created. Endocardial voltage mapping in sinus rhythm revealed a large low voltagearea and a focal pattern of activation was documented in activation mapping during VT. Inboth cases MSCT demonstrated low density areas indicative of focal fatty infiltration andmorphological and functional abnormalities which were simultaneously assessed with MRI orelectroanatomical mapping.(J Arrhythmia 2007; 23: 277–284)

Key words: ARVC/D, Multislice CT, MRI, Sudden cardiac death, Radiofrequency catheter ablation

Introduction

Arrhythmogenic right ventricular dysplasia/cardio-myopathy (ARVD/C) is uncommon type of cardio-

myopathy with fibrofatty tissue replacement.1) Thisdisease is one of the causes of sudden cardiac deathamong young people, particularly in athletes. Mag-netic resonance imaging (MRI) is a sophisticated

Address for correspondence: Kei Nishiyama MD, Departments of Cardiovascular Medicine, Kyoto University Graduate School of

Medicine, 54, Kawaharamachi, Shougoin, Sakyo-ku, Kyoto, 606-8397, Japan. TEL: 81-7-5751-3198 FAX: 81-7-5751-3299 E-mail:

[email protected]

Received 20, August, 2007: accepted in final form 18, December, 2007.

277

Nishiyama K 64-slice computed tomography imaging of ARVD/C

Case Report

method for the diagnosis of ARVD/C.2,3) Electro-anatomical mapping has been reported to provide arapid and accurate mapping that facilitates catheterablation of VT in ARVD/C.4) In addition, multislicecomputed tomography (MSCT) is fast, easy toperform, and has a more reliable image quality.MSCT is considered a clinically valuable, noninva-sive tool for assessment of myocardial pathology.However, the relationship between MSCT, cardiacMRI and electroanatomical mapping imaging inpatients with ARVD/C is unknown.

Case Report

Case 1A 69-year-old man with a history of intermittent

atrial fibrillation and hypertension was admitted to

hospital because of sustained ventricular tachycardia(VT) with right bundle branch block morphology(Figure 1). He had no family history of cardiomy-opathy or sudden death. After abolition of VT, anelectrocardiogram showed atrial fibrillation, com-plete right bundle block, and abnormal Q wave in IIIand ST depression in V4-V6 leads.

Contrast-enhanced MSCT (Aquilion 64, ToshibaMedical Systems Corporation) demonstrated lowdensity areas (�70 to �5HU) indicative of focalfatty infiltration in the anterior wall of the rightventricule (RV) outflow tract and RV trabeculationsalong the right ventricular side of the interventricularseptum (Figure 1, 2). Significant right ventriculardilatation was not observed. In addition, conspicuoustrabeculations with low attenuation (�10HU) and awedge-shaped low density area (�50 to �60HU) in

A

B

I

II

III

aVR

aVL

aVF

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aVL

aVF

V1

V2

V3

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V5

V6

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25mm/sec

Figure 1Panel A: Sustained VT with right bundle branch

block morphology (Case 1). Panel B: ECG after

abolition of VT showed atrial fibrillation, com-

plete right bundle block, and abnormal Q wave

in III and ST depression in V4-V6 leads

(Case 1). (Continued)

J Arrhythmia Vol 23 No 4 2007

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the left ventricle (LV) myocardium were observed.Cinematic display of basal short axis imagesreconstructed from the same CT data set revealedmarked wall thinning and wall motion abnormalitiesin the LV inferior wall and interventricular septum.A localized ventricular aneurysm was noted in theinferior wall of the RV. Cardiovasculr MRI wasperformed with a 1.5-T whole body scanner (Sym-phony, Siemens Medical Systems). Cine MRI imag-ing using true fast imaging with steady-state pre-cession sequence also revealed marked wall thinningand decrease in wall motion in the inferior wall andbasal interventricular septum of the LV as indicatedby MSCT imaging (Figure 2). A localized ventricularaneurysm was also noted in the inferior wall of right

ventricular base as indicated by MSCT imaging(Figure 2).

An endomyocardial biopsy specimen from the RVdisclosed extensive replacement of the myocardiumwith fibroadipose tissue and the patient was diag-nosed with ARVD/C1) (Figure 2).

We also performed ventriculography and coronaryangiography. Right ventriculograms revealed an RVejection fraction of 29.5% and a systolic bulge ofreduced RV wall motion and diffuse infero-septalaneurysm. Left ventriculograpms revealed an LVejection fraction of 25.7% and a systolic bulge ofthe infero-septal LV wall with reduced motion andaneurysm. Angiography revealed normal coronaries,suggesting LV involvement (Figure 1).

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VT1I

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aVL

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aVL

aVF

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25mm/sec

Figure 1 (Cont’d)Panel C: Sustained VT with left bundle branch

block morphology (Case 2). Panel D: ECG after

abolition of VT showed complete right bundle

block with " wave in V1 and V2 leads. VT:

ventricular tachycardia; ECG: electrocardio-

gram.


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The patient did not agree to implantable cardio-verter defibrillator (ICD) implantation and radio-frequency (RF) catheter ablation and suffered fromsudden cardiac death one year after discharge.

Case 2A 35-year-old man was admitted to hospital

because of sustained VT with left bundle branch

block morphology. He had no family history ofcardiomyopathy or sudden death. After abolition ofVT, an electrocardiogram showed complete rightbundle block with " wave in V1 and V2.

We also performed ventriculography and coronaryangiography. The RV ejection fraction in rightventriculograms was 52.3% and the LV ejectionfraction in left ventriculograms was 72.4%. An

A B

C D

Figure 2Panels A and B: Series of representative axial CT images from cranial to caudal regions illustrated low density

areas (�120 to�10HU) suggesting adipose tissues in the anterior wall of right ventricular outflow tract, in the right

ventricular trabeculations, the left ventricular myocardium and along the right ventricular side of interventricular

septum (black arrows). Panel C: End-diastolic (left) images of basal short-axis MRI confirmed marked wall

thinning in the inferior wall and basal interventricular septum of the left ventricle (black arrows). A dark band is

observed along the septum (white arrowheads) due to chemical shift artifacts. In addition, a right ventricular

localized aneurysm was observed (white arrow). Panel D: End-diastolic (left) images of basal short-axis contrast-

enhanced MSCT also confirmed marked wall thinning in the inferior wall and basal interventricular septum of the

left ventricle (black arrows) and illustrated low density areas (�120 to �10HU) suggesting adipose tissues in the

left ventricular myocardium and along right ventricular side of interventricular septum (white arrowheads). In

addition, a right ventricular localized aneurysm was observed (white arrow). MRI = magnetic resonance imaging,

MSCT = multislice computed tomography


280

endomyocardial biopsy specimen from the RVdisclosed extensive replacement of the myocardiumwith fibroadipose tissue and the patient was diag-nosed with ARVD/C1) (Figure 3).

Contrast-enhanced MSCT (Aquilion 64, ToshibaMedical Systems Corporation) also demonstratedlow density areas (�70 to �5HU) in the anteriorwall of the right ventricular outflow tract and theinferior wall of the right ventricular base (Figure 4).

Significant right ventricular dilatation and LVinvolvement was not observed. Because he sufferedfrom incessant VT, we performed RF catheterablation. Three-dimentional endocardial activationmaps of the RV were created with the CARTOsystem and NAVI-STAR catheter (Biosense-Web-ster, Diamond Bar, CA, USA). Endocardial voltagemapping in sinus rhythm revealed a large lowvoltage area in the base of the RV (Figure 4). A

A

B

Figure 3Microscopic examination of myocardial biopsy specimen (case 1: panel A, case 2: panel B) demonstrated extensive

fatty infiltration composed of mature adipose tissue. The microscopic slide shows not only fatty inflation but also

fibro-fatty infiltration replacing preexisting myocardium (hematoxylin-eosin stain), which are features supporting

the diagnosis of arrhythmogenic right ventricular dysplasia/cardiomyopathy.


281

A B

C D

← septumR A

R A R A

R A

lateral →

E

F

1.50 mV

0.00 mV

39 ms

-126 ms

Figure 4Panels A through D: Series of representative axial

CT images from right anterior oblique view illus-

trated low density areas (�120 to �10HU), suggest-

ing adipose tissues in the anterior wall (white

arrows) and along the base of the right ventricle

(white circles).

Three-dimentional endocardial activation maps of

right ventricle was created with the CARTO sys-

tem and NAVI-STAR catheter (Biosense-Webster,

Diamond Bar, CA, USA). Endocardial voltage

mapping of three-dimentional endocardial activation

maps of the RV in sinus rhythm revealed a large low

voltage area in the base of the rightr ventricle (panel

E). A focal pattern of activation which showed a

wavefront radially spreading from an earliest activa-

tion site from the base of the RV was documented in

activation mapping during ventricular tachycardia

(panel F).


282

focal pattern of activation which showed a wavefront radially spreading from an earliest activationsite at the base of the RV was documented inactivation mapping during VT. The range of activa-tion times was considerably less than the tachycardiacycle length (Figure 4). After RF catheter ablation thepatient underwent ICD implantation.

Discussion

We report two cases which were diagnosedARVD/C by endomyocardial biopsy with RVaneurysm (Case 1) or " wave of electrocardiogram(Case 2).1)

In Case 1 MRI revealed marked wall thinning anddecrease in wall motion in the inferior wall and thebasal interventricular septum of the left ventricle.Contrast-enhanced MSCT demonstrated low densityareas indicative of focal fatty infiltration not only inthe anterior wall of the right ventricular outflow tractand along the right ventricular side of interventric-ular septum but also in the inferior wall and the basalinterventricular septum of the LV. In this case thepatient suffered from VT with right bundle branchblock and superior axis morphology, which indicatedthe origin of VT was the inferior wall of the LV.

Because RV dilatation and LV involvement wasassociated with the risk of SCD in patients withARVC/D, morphological evaluation is highly usefulin risk stratification and prevention of SCD, andMRI was demonstrated to be useful for noninvasivediagnostic imaging.5–14) Compared with MRI, it wasreported that MSCT had demonstrated excellentspatial and temporal resolution which could provideanatomical and functional change in ARVC/D.15)

Bomma et al. emphasized 3 main attributes of MSCTin the evaluation of patients with ARVD/C.16) First,MSCT detected many characteristic abnormalities ofthe right ventricle. Second, MSCT provided quanti-tative assessment of RV size. Third, cine evaluationimages could provide visual assessment of contrac-tile function. They also demonstrated in quantitativeanalysis of ventricular function the data set of MSCTwere similar to values obtained from cardiac MRI. Inthis case MSCT demonstrates more detailed spatialand temporal resolution than MRI, which revealedmany characteristic abnormalities and cine evalua-tion images, and assisted the diagnosis of ARCV/Dand the estimation of the risk of SCD.

In Case 2 an electroanatomical map of the RVwas created. Endocardial voltage mapping in sinusrhythm revealed a large low voltage area in the baseof RV and a focal pattern of activation from the baseof RV also was documented in activation mapping

during VT. Contrast-enhanced MSCT also demon-strated low density areas in the inferior wall of theright ventricular base, which involved the epicardialmyocardium. In this case the patient suffered fromVT with left bundle branch block and superior axismorphology, which indicated the origin of VTexisted in the inferior wall of the right ventricularbase. It may be inferred that the origin of VT exitedin epicardial myocardium of RV because MSCTdemonstrated low density areas in epicardial myo-cardium of the base of RV and epicardial mappingmay be needed for further examination.17,18)

RF ablation has been performed in selectedpatients for VT in medically refractory patients.19)

It was reported electroanatomical mapping wasvaluable in identifying the VT mechanism, and inguiding RF ablation in patients with ARVD/C.4)

However, the correlation of MSCT and electro-anatomical mapping was not clear. In this case thelow density area which indicates focal fatty infiltra-tion was visualized along the base of the RV inMSCT, which was the same location as the lowvoltage area in SR and the earliest activation site ofVT in electroanatomical mapping. Merging MSCTand electroanatomical mapping was reported to beuseful for substrate-based mapping of scar-relatedcomplex ventricular arrhythmias.18)

Compared with MRI, MSCT shows excellentspatial and temporal resolution, which could provideanatomical and functional change in ARVC/D.Moreover MSCT can be used even after ICDimplantation. Collaboration and merging MSCTand electroanatomical mapping may be useful inRF treatment of VT in patients with ARVC/D.Further study may be needed because there are fewreports demonstrating the relation and comparisonbetween MSCT, cardiac MRI and electroanatomicalmapping in patients with ARVD/C.

Abbreviations

ARVD/C = arrhythmogenic right ventriculardysplasia/cardiomyopathy, MRI = magnetic reso-nance imaging, MSCT = multislice computed to-mography, VT = ventricular tachycardia, RV =right ventricle, LV = left ventricle, ICD = implant-able cardioverter defibrillator, RF = radiofrequency

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