Heart
Cardiomyopathies
Arrhythmogenic right ventricular

Author: R. Amita, M.D. (see Authors page)

Revised: 19 March 2018, last major update May 2015

Copyright: (c) 2015-2018, PathologyOutlines.com, Inc.

PubMed Search: Arrhythmogenic right ventricular cardiomyopathy [title] review[ptyp]

Cite this page: Amita, R. Arrhythmogenic right ventricular cardiomyopathy. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/heartarrhythmogenic.html. Accessed April 22nd, 2018.
Definition / general
  • Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a primary heart muscle disease characterized by progressive myocardial atrophy of the right ventricle, with transmural fatty or fibrofatty replacement, either segmental or diffuse, accounting for electrical instability at risk of life threatening ventricular arrhythmias
Terminology
  • Also known as arrhythmogenic right ventricular dysplasia
Epidemiology
  • Incidence varies between 1 in 1,000 and 1 in 5,000
Sites
  • Right ventricular free wall
Pathophysiology
  • ARVC is an acquired, nonischemic atrophy of the right ventricular myocardium
  • Dystrophic theory: the fibrofatty infiltration is viewed as a healing phenomenon in the setting of chronic myocarditis
  • Genetic factors: genetic predisposition to viral infection triggering an immune response, with a selective involvement of the right ventricle
Etiology
  • Genetic
    • Inherited in an autosomal dominant pattern, with variable expression
    • Point mutations in genes coding for desmosomal proteins are the main causatives for the development of this disease
Clinical features
  • Most common symptom is palpitations
  • Palpitations can occur at rest but are often triggered by physical activity
  • They may be associated with chest pain, light headedness or blackouts
  • ARVC is also a recognised cause of sudden cardiac death
Diagnosis
  • ECG:
    • Right ventricular outflow tract (RVOT) tachycardia is the most common VT seen in individuals with ARVD
    • In this case, the ECG shows a left bundle branch block (LBBB) morphology with an inferior axis
  • Signal averaged ECG (SAECG) is used to detect late potentials and epsilon waves in individuals with ARVD
  • Echocardiography may reveal an enlarged, hypokinetic right ventricle with a paper thin RV free wall
    • The dilatation of the RV will cause dilatation of the tricuspid valve annulus, with subsequent tricuspid regurgitation
    • Paradoxical septal motion may also be present
  • Cardiac MRI: to detect fatty infiltration of the RV free wall
  • Right ventricular angiography is considered the gold standard for the diagnosis of ARVD
    • Findings include akinetic or dyskinetic bulging localized to the infundibular, apical and subtricuspid regions of the RV; these findings are 90% specific
  • Transvenous biopsy of the right ventricle can be highly specific for ARVD
Case reports
Treatment
  • Medication including beta blockers, sotalol and amiodarone can be used to reduce palpitations and abnormal rhythms
  • Ablation therapy
  • Implantable cardiac defibrillator (ICD)
Clinical images

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Increase of transverse cardiac diameter

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Enlargement of right ventricle and atrium

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Cardiac echocardiogram

Gross description
  • The heart weight is usually normal and does not exceed 400 g
  • The right side of the heart appears yellowish or whitish due to fatty or fibrofatty infiltration of the underlying myocardium
  • The right ventricular inflow outflow tract appear lardaceous / fatty
  • The right ventricular free wall appears parchment like when held against a light source
  • The changes may be focal in 20% and diffuse in 80% of cases
  • Aneurysms of the right ventricular free wall, whether single or multiple, are considered a pathognomonic feature
  • Right ventricular enlargement (mild, moderate or severe) is a constant feature
  • The left ventricle and the ventricular septum are grossly normal in most cases, a paradox which explains why these hearts are able to withstand the cardiac output of a strenuous exercise performance and at the same time are electrically vulnerable because of fibrofatty infiltration of the right ventricle
Gross images

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Severe dilation of RV

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RV dilatation

Microscopic (histologic) description
  • Histology of the free wall of the right ventricle shows disappearance of the myocardium with transmural fibrofatty replacement
  • The pathologic process starts from the subepicardium and extend to the endocardium as a wave front phenomenon
  • Patchy myocarditis with myocyte death and round cell inflammatory infiltrates may be seen
Microscopic (histologic) images

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Early fibrosis and adipocytes infiltration

Differential diagnosis
  • Acquired heart disease:
    • Bundle branch re-entrant tachycardia
    • Pulmonary hypertension
    • Right ventricular infarction
    • Tricuspid valve disease
  • Congenital heart disease:
    • Atrial septal defect
    • Ebstein anomaly
    • Partial anomalous venous return
    • Repaired tetralogy of Fallot
    • Uhl anomaly
  • Miscellaneous:
    • Idiopathic RVOT tachycardia
    • Pre-excited AV re-entry tachycardia
    • Sarcoidosis