In addition to today’s resource please review the following from Life In The Fast Lane.
- Epsilon Wave.
- Arrhythmogenic right ventricular dysplasia.
- Right ventricular outflow tract VT
- ECG Exigency 008 — Sudden Syncope on the Soccer Field
In addition to today’s resource, please review the following from StatPearls:
- Sudden Cardiac Death. Allison G. Yow; Venkat Rajasurya; Sandeep Sharma. Last Update: August 8, 2022.
All that follows is from the above resoure.
Arrhythmogenic right ventricular cardiomyopathy (ARVC), a condition also known as arrhythmogenic right ventricular dysplasia (ARVD), is a genetic disorder of the myocardium. ARVC/D is due to fatty infiltration of the right ventricular free wall. This results from the mutation of genes and can cause sudden death in young people and athletes. It was first identified in 1977 by Guy Fontaine. An essential feature of this disease is the development of ventricular tachycardia with left bundle branch block pattern. It commonly presents during exercise. Identification of this disease can prevent death in patients with the disease by doing preventive measures. Genetic testing is essential in their family members to identify at-risk individuals.
Arrhythmogenic right ventricular cardiomyopathy is typically inherited as an autosomal dominant pattern with variable penetrance and incomplete expression. Approximately 40% to 50% of ARVC/D patients have a mutation in genes encoding a desmosome protein. The gene is on the chromosome 14q23-q24.There is an autosomal recessive trait variant associated with palmoplantar keratosis and wooly hair named Naxos disease.
In the general population, the prevalence of ARVC/D is 1 per 2500 to 1 per 5000. The prevalence is higher in Italy (Padua, Venice) and Greece (Island of Naxos). This disorder accounts for 5% to 10% of sudden unexplained death in individuals less than 65 years of age. It occurs in young adults and has a male to female ratio of 2.7 to 1.
Arrhythmogenic right ventricular cardiomyopathy/dysplasia pathogenesis is unknown. Apoptosis seems to play a role in pathogenesis. The disease process initiates in the subepicardial region, extends to the endocardial surface, and leads to transmural involvement.
Aneurysmal dilatation is present in 50% of the cases. An aneurysm occurs in the diaphragm, apical area, and infundibulum, known as the triangle of dysplasia. The left ventricle is involved in 50% to 67% of cases. Involvement of the left ventricle suggests a poor prognosis. The two pathology patterns seen with ARVC/D are fatty infiltration and fibro-fatty infiltration.
ARVC/D is a progressive disease. The right ventricle becomes more involved over time, leading to right ventricular failure. By the time the individual develops right ventricular failure, the left ventricle may develop histologic changes. Eventually, the left ventricle failure develops, leading to biventricular failure. The disease further progresses to congestive heart failure, atrial fibrillation, and thromboembolic events.
Microscopic features of the right ventricle show several changes of which the dominant feature is the presence of fibrofatty or fat replacement of the myocardial muscle. The muscles may show a moth-eaten appearance, mild inflammation, and scarring. Very rarely does one see frank myocyte necrosis. Some researchers are using immunohistochemistry to reveal the diffuse loss of desmosomal proteins, which is suggestive of an arrhythmogenic right ventricle.
History and Physical
Arrhythmogenic right ventricular cardiomyopathy/dysplasia presentation varies from the asymptomatic state to palpitations, fatigue, syncope, or even cardiac arrest during exercise. Sometimes one will see prominence in the left side of the heart due to enlargement of the right Ventricle. Other than this, the physical exam is usually unremarkable.
Diagnosis of ARVC/D is challenging. No one test can make the diagnosis, and multiple diagnostic tools are utilized including history, ECG, echo, MRI, and endomyocardial biopsy.
- ECG – The most common ECG abnormality seen in ARVC/D is T wave inversion in the precordial leads V1 to V3. The epsilon wave is found in 50% of cases of ARVC/D. These are due to post excitation electrical impulses of small amplitude, and they tend to occur at the end of QRS complexes and during the beginning of ST segment; this is due to delayed right ventricular activation. Ventricular ectopy of left bundle branch block morphology with QRS axis -90 to +100 degree is from fatty degeneration of right ventricle (RV apex, RV inflow tract, RV outflow tract).*
*Please see and review Epsilon Wave. Mike Cadogan and Robert Buttner. Feb 4, 2022. From Life In The Fast Lane. This excellent resource has a number of excellent electrocardiographic examples of ARVC/D.
- Echocardiography – Echocardiography may reveal an enlarged right ventricle (RV), hypokinetic RV, and paper thin RV free wall.
- Cardiac MRI – Cardiac MRI is an excellent tool for visualizing the right ventricle. It may reveal a transmural diffuse bright signal in the RV free wall due to myocardial atrophy with fatty replacement.
- Endomyocardial biopsy – Transvenous biopsy of the right ventricle can be highly specific for ARVC/D, but it has low sensitivity.
The diagnosis of ARVC/D is based on a combination of major and minor criteria. Diagnosis of ARVC/D requires two major criteria or one major and two minor criteria or four minor criteria.