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"Quality is not an act. It is a habit."


Aristotle


Arrhythmogenic right ventricular dysplasia

date : 11.12.2012


T. Monovska
L. Nikolova
G. Kirova
V.Traykov


Imaging Diagnostic Department; Cardiology Department ; Tokuda Hospital Sofia; Vaptzarov blvd.51 B; 1407 Sofia

dori_monovska@yahoo.com


Keywords: arrhythmogenic right ventricular dysplasia, fibrofatty replacement, MRI


Clinical history: 41-year old patient presented at Cardiology department with chest tightness during exercise with additional family history of sudden cardiac death.Previous syncope episode with monomorphic tachycardia and left bundle branch block,was documented,normalized with cardiovertion.Dilatation of right ventricle with reduced systolic function and prominent trabeculation on echocardiography. Negative T waves in leads V1-V3 and prolonged terminal activation duration of QRS complex on ECG( fig.1,2).


Imaging findings:

The MRI findings are dilatation of right ventricle and right ventricle outflow tract. Global thinning of the right ventricular myocardial wall. Hypokinesia with dyskinesia of cardiac apex in diastole in comparison with the middle part and the base of right ventricle. Compensatory local dilatations of right ventricle and right ventricle outflow tract are visualized.Deformation of the moderator band is detected as a result of the hypo and dyskinetic functional changes in cardiac apex.The dimensions of the left ventricle and the contractility of left ventricle wall and septal myocardium are preserved. No pathological changes in both atria,pleura,pericardium aortic and mitral valves. As an additional finding a small jet between both ventricles is evaluated, suspicious for interventricular defect( fig.3,4,5).


Final diagnosis: Arrhythmogenic right ventricular dysplasia


Discussion:

Arrhythmogenic right ventricular dysplasia (ARVD) is a type of cardiomyopathy morphologically presented by fatty or fibrofatty infiltration of the right ventricular myocardium creating substrate for macroreentrant ventricular tachycardias.This determines the most frequent clinical manifestation of this condition –monomorphic ventricular tachycardias with left bundle branch block pattern.ARVD is more frequent among males and is the result of genetically determined dysfunction of desmosomic proteins.They are crucial for cardiac cell-to-cell coupling and play a major role in myocardial mechanics.There are two morphological types of ARVD: fatty and fibrofatty.In the fatty form there is almost complete replacement of myocardium but without ventricular wall thinning. This form mainly affects the right ventricle.The fibrofatty type is characterized also by thinning of the right ventricular wall.The left ventricular myocardial wall might also be affected in the latter.The right ventricle changes also consist of mild to severe dilatation,aneurysms and segmental hypokinesia.The pathomorphological changes are usually transmural and are most expressed in the outflow tract,the apex and the infundibulum forming the so-called triangle of dysplasia.ARVD is diagnosed following the Task Force Criteria published in 1994 by Mc Kenna.They are grouped into morphological, ECG criteria – depolarization and repolarization abnormalities, histopathological alterations,presence of arrhythmias and family history.ECG usually shows depolarization abnormalities in leads V1-V3,with Epsilon wave and prolonged QRS terminal duration due to the late activation of parts of right ventricular wall . The late is a result of poor cell-to-cell coupling. Frequently T wave inversion in leads V1-V3 is found as a result of right ventricular repolarization. MRI imaging allows better visualization of myocardial fatty and fibrofatty replacement.This imaging modality is very useful for detection of high signal intensity of fat in the right ventricular myocardium on T1-weighted images.MRI can be also used for evaluation of both systolic and diastolic dysfunction of the cardiac chambers.Therefore MRI is the modality of choice to study the morphological right ventricular changes – dilation,localized aneurysms,wall motion abnormalities,etc.ARVD follows a progressive course and might lead to right-sided heart failure. The condition is also among the cause of sudden cardiac death.Therapy of ARVD includes antiarrhythmic medications,implantable cardioverter-defibrillators and/or cather ablation. Heart transplantation might also be an alternative life-saving procedure in some cases.


Differential diagnosis:

ARVD should be differentiated from congenital heart disease (Ebstein anomaly,atrial septal defect,partially anomalous pulmonary venous drainage and Uhl’s anomaly),idiopathic ventricular tachyarrhythmias arising from the right ventricular outflow tract,myocarditis, sarcoidosis,dilated cardiomyopathy.In some cases ARVD should be differentiated from Brugada syndrome.


Take home messages:

ARVD is a type of cardiomyopathy, characterized pathologically by fibrofatty replacement of the right ventricle myocardium and clinically presented most frequently by ventricular tachyarrhythmias originating from the right ventricle.ARVD is one of the causes of sudden cardiac death.Diagnosis is established based on the Task Force Criteria.MRI is the mainstay imaging modality able to demonstrate not only fatty replacement but also functional abnormalities of right ventricle and right ventricular flow tract. ARVD therapy includes antiarrhythmic drugs, implantable cardioverter defibrillator and/or catheter ablation.Cardiac transplantation is a viable alternative in some cases.


Bibliography:

1.Hein W.M.Kayser, E.E. van der Wall, Mohan U.Sivananthan, S.Plein et al; Diagnosis of Arrhythmogenic Right Ventricular Dyplasia: A Review; Radiographics; 2002; 22:639-650; 2.D. Corrado, C. Basso, G. Thiene; Arrhythmogenic Right Ventricular Cardiomyopathy: an update; Heart 2009; 95: 766-773; 3.E.Vermes, O.Strohm, A.Otmani; Impact of the Revision of Arrhythmogenic Right Ventricular Cardiomyopathy/ Dysplasia Task Force Criteria on Its Prevelence by CMR Criteria, JACC: Cardiovascular Imaging, Vol.4, № 3, 2011:282-7; 4.K. Gear, F. Marcus; Arrhythmogenic Right Ventricular Dysplasia/ Cardiomyopathy; Circulation 2003; 107:e31-e33; 5.S. Abbara, R. Q. Migrino, D. E. Sosnovik et al; Value of Fat Suppression in the MRI Evaluation of Suspected Arrhythmogenic Right Ventricular Dysplasia; AJR 2004; 182: 587-591; 6.F.I. Marcus, W.J. Mc Kenna, D. Sherrill et al; Diagnosis of Arrhythmogenic Right Ventricular Cardiomyopathy/ Dyspasia : Proposed Modification of the Task Force Criteria; Circulation 2010



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