Arrhythmogenic right ventricular dysplasia (ARVD) is a disorder is a rare disease in which myocardium that is normal is replaced by fibrofatty tissues. This disorder involves the ventricle on the right but the left one may be affected by the disease as well. The rare type of cardiomyopathy occurs when the ventricle on the right has tissue that is scared or has died. When in affect it interrupts the hearts electrical signals and causes arrhythmias. This disease is among one of the deadliest with young athletes and can affect people of different activity levels.
Background of arrhythmogenic right ventricular dysplasia (ARVD
Arrhythmogenic right ventricular dysplasia (ARVD) is a genetic cause for sudden cardiac arrest or (SCA), this condition is when the heart cease beating. Normal heart tissues are replaced with myocyte, fat, and fibrous tissue that is scared. This occurs in the ventricle to the right of the heart. The replacement of the normal tissue predisposes the person to abnormal heart rhythms and electric activity called arrhythmogenic arrhythmia. The disease affects 1 out of 1000 people up to 5000. This disease is hard to diagnose and can be confused with other diseases. This disease is relevant today because of the sudden deaths in individuals 30 years of age and younger with 20% of those deaths being youth.
Arrhythmogenic right ventricular dysplasia has 30% of their cases that occur in families. Diagnosis are hard to make because genes from the parents need to express themselves in affected patients. If the genes in the patient do not expose themselves, the disease may come in varying intensities, this condition is called variable expression. Low penetrance or variable expression can make it difficult to make a diagnosis. The genes that are tied to ARVD comes in two forms inheritance, autosomal dominant and autosomal recessive. The form that is most common is the autosomal dominant form. Anyone possessing this strain is at risk for having the syndrome. The offspring of these people possessing this strain will have a 50% increase in having the disease. The autosomal recessive form is less common. The offspring will need to inherit the genes from both the parents or they will be silent carriers with no physical manifestation of the disease. The autosomal recessive strain is associated with Naxos a disease where ARVD and other disorders are of the skin and the hair. Naxos has been linked to the autosomal recessive inheritance of the mutant genes.
The mutant genes code for similar proteins whether a person has the autosomal recessive or dominant traits. Remaining heart cells are held together by desmosomes that are adjacent to the heart. This is crucial in keeping the structure in the heart. Defective desmosomes detach from one another when they are placed under high stress activity like working out. This can lead the cells dying. The cells dying then causes inflammation, scar formation, and fat deposition. The fibrofatty islands predispose the person to develop arrhythmias. The disease’s initial process is localized and then spreads from discrete areas to the rest of the right ventricle. The left ventricle is normally spared. If it does occur it occurs very late.
Clinicals and Diagnosis
When the symptoms are exposed they occur around 30 years of age on average. Unfortunately, patients are from 10 to 50 years of age. Both men and women are affected the same. The most common and visible symptoms are due to arrhythmia’s or to decreased blood supply to vital organs like the brain. Heart palpitations or awareness of one’s heartbeat, dizziness, shortness of breath, syncope (lose of conciseness), or near scope are also symptoms of ARVD. Some patients demonstrate SCA or the patient is asymptomatic and the diagnosis is suspected due to family history. Noninvasive tests like echocardiogram or electrocardiogram can assist with discovering the presence of ARVD. Diagnosis present difficult challenges, normal hearts have some degree of fat and fibrous tissue. Patients who show a specific arrhythmia called ventricular tachycardia or (VT) coming from (RV) in the absence of overt heart disease, or SCA, occurring during exercise should be considered patients of ARVD. There is a list of criteria to make sure the correct diagnosis is made. Patients that have the less common form of the disease can be missed. The criteria are; family history, ECG depolarization/conduction abnormalities, repolarization abnormalities, tissue characterization of walls, global or regional dysfunction, and structural alterations, and arrhythmia. There is a major and a minor criterion for each category that was listed. Family history has the major category that familial disease confirmed at surgery or necropsy. The minor criteria are family history of premature sudden death at the range of 35 years or younger and ARVD was suspected. The next category has a criteria of epsilon waves or prolongation of the QRS complex that is 110 or less msec in the right precordial leads, or late potentials seen on signal averaged ECG. The following category only has a minor criterion that states that the inverted T waves in the right precordial leads in patients is less than 12 in the absence of right bundle branch block. Tissue characterization of walls has a major criterion of fibrofatty replacement of myocardium on endomyocardial biopsy. Next the category has a major and minor criterion of severe dilation and reduction of the right ventricle ejection fraction with minimal left ventricle involvement, localized right ventricle aneurysms, and severe segmental dilation of the right ventricle. The minor criteria are mild global right ventricle dilation or ejection fraction reduction with normal left ventricle, mild segmental dilation of the right ventricle, and regional right ventricle hypokinesia. Lastly, the final category has a minor criteria of the left bundle branch lack type ventricular tachycardia (sustained and un-sustained) (ECG, Holter, exercise testing) and frequent ventricular extra systoles (more than 1,00/24 h) (Holter).
There is currently no treatment present that can completely cure the disease. Therapy has a goal of preventing death from (VT) or (SCA). Therapeutic treatment is accomplished by using implanted cardioverter-defibrillator or (ICD). The ICD’s are devices that are placed underneath the patient’s skin and during it monitors the hearts electrical activity continuously. If an arrhythmia is detected the ICD sends a series of “shocks” to get the heart back to a normal rhythm. This treatment is recommended for those who have documented an episode of a sustained VT or SCA. It can also be used for patients who are thought to be at a higher risk for SCA. Medications are not guaranteed and not 100% effective. Beta blockers can be used against milder forms of the disease with no symptoms or suggestive arrhythmias. Increased physical activity may increase the spread of the disease and lead arrhythmias. Patients with ARVD should not participate in highly active actives. Low intensity activities like golf are suggested and considered safe.
In closing, Arrhythmogenic Right Ventricular Dysplasia is a deadly disease that affects people ages 50 years and less and ARVD can be inherited if there is a presence of the gene in the offspring. The disease affects the right ventricle by creating scared tissue of the damaged normal tissue. This results in abnormal heart activity known as arrhythmia’s and palpitations. There are no current treatments, yet therapy and light activity help keep death at bay. More attention is being drawn to the disease because of the increase in death of athletic youth and individuals under the age of 35 years.