A closer look at 4 of the rarest heart diseases

20160921150000, Teo Jun Hong
There are many heart diseases that are relatively unheard of despite the stark prevalence of heart diseases in our region.
Genetic diseases that affect the proper functioning of the heart are mostly caused by mutations in one or more genes. These mutations would either affect the structure or function of the heart muscle. Many of these diseases are rare, and inherited from one, or both parents. Here we take a look at four of the rarest heart diseases found thus far.

1. Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy (ARVD/C)


ARVD/C is a genetic disease in which normal heart tissue in the right ventricle is progressively replaced with fat and fibrosis (scar tissue). Patients suffering from ARVD/C would suffer from arrhythmias, or abnormal heart rhythms resultant from structural abnormality. Tissue damage occurs predominantly in the right ventricle in the early stages.

Common, non-specific symptoms of this disorder are palpitations, nausea, dizziness, heart fluttering, and heart racing. Sometimes, patients experience symptoms of heart failure.

Progression of this disease often comes in four steps, although not all patients experience it as such. In the first “concealed phase”, small changes often occur in the right ventricle. The “overt phase” is when the heart muscle suffers from noticeable changes, and causes abnormal heart rhythms. Later on, the right ventricle would be weakened and stretched, affecting its ability to pump, and at the final stage, the whole heart’s pumping ability would be significantly weakened.

The treatment of ARVD/C would involve the implantation of an implantable cardioverter defibrillator (ICD). Medications, to ease the stress on the heart would be prescribed. The most extreme form of treatment would be a full heart transplant, and is reserved for patients with an extremely weak heart and when no other treatments prove successful.

ARVD/C affects an estimated one in every 5,000 people across both genders, and accounts for about 20% of all sudden death from cardiac arrest in people younger than 35 years. Some form of genetic inheritance is possible through autosomal dominant inheritance, autosomal recessive inheritance, and also compound heterozygosity and digenic mutations. However, even today, the specific genetic cause of ARVD/C is yet to be fully comprehended.

2. Brugada Syndrome


Brugada syndrome is a life-threatening, frequently inherited disorder characterised by a Brugada sign – an arrhythmia or abnormal heart rhythm – which affects the heart’s ability to pump blood effectively, and as such, the blood would not be able to travel throughout the body.

Brugada is caused by polymorphic ventricular tachycardia, and may degenerate into ventricular fibrillation and lead to fainting, cardiac arrest, and if left untreated, will ultimately result in death.

Signs of Brugada may include syncope and cardiac arrest occurring most often at night, trashing around on bed at night, atrial fibrillation and fever.

Treatment of Brugada would involve the implantation of an ICD, and certain drugs that counteract the ionic current imbalance can be prescribed. Brugada affects approximately one in every 2,000, but the prevalence is difficult to estimate. It is noted that this condition is more common in Southeast Asia, and in the Japanese, with incidences as high as one in 714.

3. Eisenmenger Syndrome


Eisenmenger syndrome results from the combination of pulmonary hypertension and right-to-left shunting of the blood within the heart as a result of ventricular septal defect (VSD), or more commonly known as hole-in-the-heart. This allows for an increase in blood flow into the lungs resulting in pulmonary hypertension.

Most sufferers do not exhibit any symptoms until their late 20s to early 30s, and such symptoms are usually as a result of inadequate oxygen supply to cells. The most notable symptoms include bluish discoloration of the skin and mucous membranes, and other symptoms include difficulty breathing (dyspnea), fatigue, lethargy, and arrhythmias.

There is no specific cure for Eisenmenger, and treatment is based on specific symptoms shown by each individual, thus it often requires the coordinated efforts of an entire team of doctors, including hematologists and lung specialists. Additionally, pregnancy is contraindicated in women suffering from Eisenmenger, as there is significant risk for both mother and child. The frequency is as rare as 9 in 1,000,000.

4. Ellis-van Creveld Syndrome


This syndrome is a rare genetic condition commonly found among Amish people. Sufferers of this syndrome are characterised by short-limb dwarfism, physical deformities, and causes atrial septal defects – a defect between the heart’s two upper atria.

This can lead to shortness of breath, respiratory infections or arrhythmias, and can lead to eventual heart failure. The frequency of occurrence is as rare as one in 200,000, but is difficult to estimate as its frequency is rare in the general population. Also, many babies with this condition die in early infancy, due to a small chest or heart defect.

Treatment is still yet unavailable for Ellis Van Creveld syndrome, but many of the complications can be treated. It is often necessary to treat respiratory distress shortly after birth that results from a narrow chest and/or heart failure. Natal teeth should be removed because they can interfere with feeding. As with Eisenmenger Syndrome, treatment often requires the coordinated efforts of a team of medical professionals. MIMS

Sources:

http://www.hopkinsmedicine.org/heart_vascular_institute/clinical_services/centers_excellence/
arvd/patient_resources/questions.html
https://www.bhf.org.uk/heart-health/conditions/cardiomyopathy/arrhythmogenic-right-ventricular-cardiomyopathy
http://www.livestrong.com/article/80231-rare-genetic-diseases-heart/
http://emedicine.medscape.com/article/163751-overview#a1; http://www.csanz.edu.au/documents/guidelines/clinical_practice/Brugada_Syndrome.pdf
http://rarediseases.org/rare-diseases/eisenmenger-syndrome/
http://www.orpha.net/consor/cgi-bin/OC_Exp.php?Lng=EN&Expert=97214
https://ghr.nlm.nih.gov/condition/ellis-van-creveld-syndrome#diagnosis https://medlineplus.gov/ency/article/001667.htm


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