What are the other Names for this Condition? (Also known as/Synonyms)

• Arachnocytosis of the Myocardium
• Infantile Cardiomyopathy with Histiocytoid changes
• Purkinje Cell Hamartoma

What is Histiocytoid Cardiomyopathy? (Definition/Background Information)

• Histiocytoid Cardiomyopathy (HICMP) is a rare but serious condition that causes arrhythmias of the heart (irregular heartbeats). It is generally diagnosed in infants and very young children
• In many cases, an abnormal growth of Purkinje cells (that occur as small nodules) is noted with this condition. The Purkinje cells are cells responsible for electrical activity in the heart
• Apart from a family history of Histiocytoid Cardiomyopathy, no other significant risk factors have been identified. The cause of the condition is also generally unknown. However, research scientists have proposed various possibilities that include viral infections, congenital glycogen storage disorders, and exposure to harmful chemicals during pregnancy
• The signs and symptoms of Histiocytoid Cardiomyopathy may include fluid accumulation in the brain and lungs, heart murmur, breathing difficulties, and congenital cataracts. Severe cases of Histiocytoid Cardiomyopathy can result in complications including heart failure, heart dysfunction, and heart defects
• The diagnosis of Histiocytoid Cardiomyopathy might involve a thorough physical evaluation by a healthcare provider, imaging studies of the heart, electrophysiological studies, and other specialized tests to evaluate functioning of the heart
• The treatment of Histiocytoid Cardiomyopathy includes the management of arrhythmias using anti-arrhythmic medication and surgical removal of the nodular growths where possible. However, despite suitable treatment measures, the prognosis of the condition is unpredictable; it is based upon the severity of each case

Who gets Histiocytoid Cardiomyopathy? (Age and Sex Distribution)

• Histiocytoid Cardiomyopathy occurs very infrequently. It is seen in very young children up to 2 years of age. About 1 in 5 cases (20%) are diagnosed within 30 days of birth
• Both males and females are affected, but it is more common in females (male-female ratio is 1:3)
• All races and ethnic groups are at risk for the condition
• However, Histiocytoid Cardiomyopathy is more common in Caucasians than other races; 4 in 5 cases (80%) are noted in them. 15% of the affected population are African Americans. The condition is very rare in the Asian population

What are the Risk Factors for Histiocytoid Cardiomyopathy? (Predisposing Factors)

Some risk factors for Histiocytoid Cardiomyopathy include:

• Family history of the condition, which is seen in 1 in 20 cases (5% of the affected individuals)
• Young girl babies seem to have a higher risk
• Caucasian race

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Histiocytoid Cardiomyopathy? (Etiology)

The cause of development of Histiocytoid Cardiomyopathy is generally unknown. An abnormal growth of the Purkinje cells, in nodular form, is observed. Since, Purkinje cells play a role in the heart’s electrical activity; these growths are thought to disrupt their function resulting in cardiac arrhythmias.

Researchers believe that the following factors may be possible causes of this heart abnormality:

• Toxic exposure during pregnancy
• Viral infections
• Glycogen storage disorders
• Mitochondrial myopathy: Some believe Histiocytoid Cardiomyopathy is a mitochondrial disorder, but this has not been conclusively proven yet
• In individuals with a family history, researchers believe that it may be an X-linked mutational disorder

Research is currently being undertaken to identify the relevant causal factors.

What are the Sign and Symptoms of Histiocytoid Cardiomyopathy?

The signs and symptoms of Histiocytoid Cardiomyopathy observed in young children include the following:

• Presence of small nodules that range in size from 1 mm to 1.5 cm in the heart
• Small head (microcephaly)
• Fluid buildup in the brain (hydrocephalus); fluid accumulation in the lungs
• Cleft palate
• Difficulty breathing, palpitations
• Heart murmur
• Cataracts

How is Histiocytoid Cardiomyopathy Diagnosed?

A diagnosis of Histiocytoid Cardiomyopathy may be undertaken using the following tests and exams:

• Complete evaluation of family (medical) history, along with a thorough physical examination; including examination of the heart (with special emphasis to signs such as abnormal heart sounds)
• Electrocardiogram (EKG): It is used to measure the electrical activity of the heart to detect arrhythmias
• Electrophysiological studies of the heart to determine where arrhythmia is getting generated in the heart, is often helpful
• CT or MRI scan of the heart
• Electron microscopic studies
• Echocardiography: This procedure uses sound waves to create a motion picture of the heart movement
  • It can help show the size and shape of the heart and how well the chambers and valves are working
  • It can also help visualize the tumors, especially the large tumors; 1 mm and lesser-sized tumors may not be visible though
• Doppler ultrasound: Sound waves are used to measure the speed and direction of blood flow
• Tissue biopsy of the nodules (or myocardial biopsy):
  • A tissue biopsy of the nodule is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
  • Biopsy specimens are studied initially using Hematoxylin and Eosin staining. The pathologist then decides on additional studies depending on the clinical situation
  • Sometimes, the pathologist may perform special studies, which may include immunohistochemical stains, molecular testing, and very rarely, electron microscopic studies to assist in the diagnosis

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Histiocytoid Cardiomyopathy?

Some potential complications of Histiocytoid Cardiomyopathy include:

• Severe arrhythmias
• Heart failure; enlarged heart (cardiomegaly) due to heart failure
• Endocardial fibroelastosis (scarring of the lining of the heart)
• Hypoplastic left heart syndrome or poor functioning of the left side of heart
• Histiocytoid Cardiomyopathy may be associated with other heart defects such as ventricular septal defect (VSD) and atrial septal defect (ASD)
• Fatty liver and renal abnormalities such as benign renal cyst
• Sudden infant death syndrome, which is seen to occur in 1 in 5 cases

How is Histiocytoid Cardiomyopathy Treated?

Histiocytoid Cardiomyopathy may be treated through the following measures:

• In order to manage children with arrhythmias, anti-arrhythmic medication is administered. If the arrhythmia persists for a long period of time, then surgical treatment measures may be considered
• Surgical removal of the nodules
• Occasionally, in children with extensive heart nodules, heart transplantation may be a treatment option
• Observation and periodic checkups to monitor the condition is recommended

In some rare cases, the nodules/tumors may disappear over time without any surgical treatment.

How can Histiocytoid Cardiomyopathy be Prevented?

Presently, there are no specific methods or guidelines to prevent Histiocytoid Cardiomyopathy.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child

What is the Prognosis of Histiocytoid Cardiomyopathy? (Outcomes/Resolutions)

• The prognosis of Histiocytoid Cardiomyopathy depends on the severity of the underlying signs and symptoms. Nevertheless, the prognosis is guarded and is assessed on a case-by-case basis
• On rare occasions, the tumors disappear on their own without surgical treatment

Additional and Relevant Useful Information for Histiocytoid Cardiomyopathy:

The following article link will help you understand other heart conditions:

http://www.dovemed.com/healthy-living/heart-center/