Arrhythmogenic Right Ventricular Cardiomyopathy

What is Arrhythmogenic Right Ventricular Cardiomyopathy?

It was previously called ARVD (Arrhythmogenic right ventricular dysplasia). Myocardium in the right ventricle is replaced by fibro fatty tissue. This is a condition in which a patient can have sudden cardiac death secondary to VT/VF. These patients have a family history of sudden cardiac death. It is a rare form of genetic disorder. Mainly due to mutations of genes. Genes mutated: gene encoding for cardiac desmosome proteins. Inheritance type: autosomal dominant (50% of patients).

Cardiac Desmosome

It anchors the ends of cardiac muscle fibers together. It prevents separation of cells whenever there is a stress of volume overload. It contains transmembrane cadence:

1. Desmoglein 2
2. Desmocollin 2

These 2 are anchored to armadillo protein.

• Desmoplakin
• Plakophillin 2

In Arrhythmogenic Right Ventricular Cardiomyopathy, there is a destruction of these cardiac desmosomes. Because of the gene mutation. There will be disruption of myocyte junction and adhesions. This disrupted area is replaced by deposits of Fat and fibrous tissue.

Dilatation of Right Ventricular myocardium

• Better visualized in MRI (IOC) followed 2D echo
• Autosomal recessive forms
  • Cardio Cutaneous syndromes
    • Naxos disease
    • Carvajal Syndrome

Naxos disease

The name Naxos is given because it was first described by families that originated from the Greek island Naxos. Defect

• In Plakophillin 2
• In Plakoglobin

Clinical manifestations

A: Wooly hair

B, C: Palmoplantar keratoderma

Carvajal Syndrome

There is mutation of desmoplakin.

• Wooly hair
• Palmoplantar Keratoderma
• Defective Right and left ventricle (increases risk of SCD)

Clinical Features in ARVC 

• Incidence: 2nd to 5th decade of life.
• Manifestations: Palpitations
• Cardiac output decreases so patients can have syncope attacks.
• Development of cardiac arrest
  • Secondary to VT
  • This VT - monomorphic or polymorphic VT.

Late features:

• Rare development of heart failure- Due to involvement of right and left ventricles.

Investigation

• MRI: Investigation of choice
• 2D Echo
• ECG
  • Left Bundle Branch Block pattern (LBBB)- In lead V1.
  • The right ventricle is arrhythmogenic causing the right ventricle to originate VT .
  • In lead V1

ECG changes

• Deep broad S wave in Lead V1
• Wide QRS complex
• R wave in V6 is tall and broad
• 85% of patients with ARVC: T waves are inverted (in right sided leads).

Epsilon Wave

Epsilon wave: It is the continuation of the S wave. Delayed or prolonged depolarization of the base of the right ventricle will give the epsilon wave. In this delayed or prolonged S wave upstroke, there is a notched deflection upwards i.e., epsilon wave.

ARVD MRI

• MRI - Investigation of choice
• It shows right ventricle enlargement.
• The thin right ventricle is hypokinetic or Akinetic.
• In contrast enhanced MRI - presence of scar. Rarely, there can be left ventricular involvement as well.
• Cardiac Magnetic Resonance imaging (CMR) advantage over Echo. Quantitative and volumetric assessments of right ventricle. Presence of fibro fatty right ventricular myocardium.

ARVD 2D Echo

Presence of dilatation of RV apex: Aneurysm of RV. Thin-walled right ventricle - Akinetic or Hypokinetic

Revised Task Force criteria for the arithmetic cardiomyopathy

Definitive diagnosis

2 major or 1 major and 2 minor criteria or 4 minor from different categories.

Borderline diagnosis

1 major and 1 minor or 3 minor criteria from different categories.

Possible diagnosis 

1 major or 2 minor criteria from different categories

Parameters of revised Task Force criteria

Global and or regional dysfunctional and structural alterations – Diagnosed by 2D Echo, MRI, right ventriculography. Tissue characterization of wall – Done by biopsy. Repolarization abnormalities – Diagnosed on ECG. Depolarization/conduction abnormalities - Diagnosed on ECG.

Major

By two-dimensional echocardiography: Regional RV akinesia, dyskinesia, or aneurysm and one of the following (end diastole):

Parasternal long-axis view of the RVOT (PLAX) ≥ 32 mm (≥ 19 mm/m2)

Parasternal short-axis view of the RVOT (PSAX) ≥ 36 mm (≥ 21 mm/m2)

Or Fractional area change < 33%

By MRI: Regional RV akinesia, dyskinesia, or dyssynchronous RV contraction and one of the following: Ratio of RVEDV to BSA ≥ 110 mL/m2 (male) or ≥ 100 mL/m2 (female) or RVEF ≤ 40%

By RV angiography: Regional RV akinesia, dyskinesia, or aneurysm

Minor

By two-dimensional echocardiography: Regional RV akinesia, dyskinesia and one of the following (end diastole):

PLAX RVOT ≥ 29 to < 32 mm (≥ 16 to < 19 mm/m² )

PSAX RVOT ≥ 32 to < 36 mm (≥ 18 mm to < 21 mm/m²)

or

Fractional area change > 33% to ≤ 40%

By MRI

Regional RV akinesia, dyskinesia, or dyssynchronous RV contraction and one of the following: Ratio of RVEDV to BSA ≥ 100 to < 110 mL/m2 (male) or ≥ 100 to < 110 mL/m2 (female) or RVEF < 40% to ≥ 45% BSA ≥ 100 to < 110 mL/m2 (male) or ≥ 100 to < 110 mL/m2 (female) or RVEF < 40% to ≥ 45%

Treatment of ARVD 

TOC: Placement of ICD (Implantable cardioverter defibrillator). Anti Arrhythmogenic drug: not very successful. Patients can develop monomorphic VT of RV: well tolerated as it is of RV origin, so LV function is preserved, and cardiac output is good. If a patient develops polymorphic VT – there is increased risk of SCD.

Drugs and Intervention

• Beta blockers
  • Sotalol - exercise induced VT.
  • Sotalol is effective in ARVC.
• Flecainide: Class I AADs.
• Amiodarone
• ICD will prevent
  • Sudden cardiac death
  • Syncope attacks
  • Improve the lifestyle of an individual.
• Catheter Ablation
  • Can be done in well tolerated monomorphic VT i.e., when LV function is good.
  • Ablation is given to endocardial and epicardial surfaces of the heart.
  • On ablation - in 85% of individuals, 3 years survival rate is documented.
• Mechanical stress is reduced by ACE inhibitors and Nitrates

Also read: High-yield NEET SS Medicine Neurology Questions

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