Endocardial fibroelastosis (EFE) is an uncommon heart condition that primarily affects infants and young children. It is defined by a characteristic thickening of the inner lining of the heart’s chambers. This thickening makes the heart muscle stiff and less able to pump blood effectively, leading to significant health problems. This article provides an overview of the disorder, its causes, symptoms, and treatment.
Understanding Endocardial Fibroelastosis
The heart’s four chambers are lined by a thin membrane called the endocardium. In endocardial fibroelastosis, this lining becomes abnormally thick and dense from the buildup of fibrous and elastic tissue, a process known as fibroelastosis. The resulting layer is opaque, often described as having a porcelain-like appearance, and most commonly affects the left ventricle.
This structural change impairs the heart’s function. The thickened endocardium makes the ventricular walls stiff, preventing the chamber from relaxing and filling with blood properly between beats. This impaired relaxation compromises the heart’s ability to pump blood efficiently, which can lead to an enlarged heart and symptoms of heart failure.
EFE is categorized into two main types. Primary EFE occurs as an isolated condition without any other structural heart abnormalities, and its direct cause is often unknown. Secondary EFE develops with other conditions, most commonly congenital heart defects like aortic stenosis or hypoplastic left heart syndrome. In these cases, the fibroelastosis is a reaction to the stress placed on the heart.
Exploring the Causes of EFE
The origins of primary endocardial fibroelastosis are not fully understood, but research points to several potential factors. A genetic predisposition is believed to play a role, with specific forms passed down through X-linked or autosomal recessive inheritance patterns. For instance, mutations in genes such as the TAFFAZIN gene have been linked to EFE.
Infections are also thought to be a possible trigger. Studies suggest a connection between viral illnesses, such as mumps or coxsackievirus during pregnancy or early infancy, and the development of EFE. The theory is that the virus or the body’s immune response could cause inflammation and injury to the endocardium.
Other theories involve metabolic disorders or autoimmune responses. Conditions like carnitine deficiency have been associated with secondary EFE. An autoimmune reaction, where the body’s immune system mistakenly attacks its own heart tissue, has also been proposed as a potential mechanism. In many instances of primary EFE, the exact cause remains unidentified.
Recognizing Symptoms and Early Indicators
The symptoms of endocardial fibroelastosis typically appear suddenly and progress rapidly, usually within the first year of life. One of the most common signs is respiratory distress. An infant may be seen breathing rapidly, having difficulty catching their breath, or making grunting sounds. A persistent cough and wheezing can also be present.
Poor feeding and a failure to thrive are also prominent indicators. An infant with EFE may tire easily during feeding, consume less milk than expected, and fail to gain weight at a normal rate. This is often accompanied by general lethargy, with the baby appearing excessively tired, weak, or irritable.
As the condition progresses, signs of congestive heart failure often develop. This can manifest as swelling, known as edema, in the legs, abdomen, or around the eyes. The baby’s skin might feel cool or clammy due to poor circulation, and a bluish tint to the skin, lips, or fingernails, called cyanosis, may appear.
Diagnostic Procedures for Confirmation
Diagnosing endocardial fibroelastosis involves several procedures to visualize the heart and assess its function. The primary tool for diagnosis is an echocardiogram. This non-invasive ultrasound of the heart allows cardiologists to see the thickened endocardium, measure the thickness of the heart walls, and evaluate ventricular pumping. An echocardiogram can reveal an enlarged heart and poor ventricular function.
A chest X-ray is often performed to get a broader view of the chest cavity. This imaging can show the overall size and shape of the heart, which is frequently enlarged (cardiomegaly). The X-ray also helps assess the condition of the lungs and can show fluid buildup, a sign of congestive heart failure.
An electrocardiogram (ECG or EKG) is used to record the heart’s electrical activity. It can detect abnormalities related to the strain on the heart muscle, such as ventricular hypertrophy or arrhythmias. In some complex cases, an endomyocardial biopsy, which involves taking a small tissue sample from the heart lining, may be considered. A biopsy can confirm the diagnosis but is performed cautiously due to its risks.
Treatment Modalities and Prognosis
Treatment for endocardial fibroelastosis is supportive, focusing on managing the symptoms of heart failure and improving heart function. There is no cure to reverse the thickening of the endocardium. Medical therapy involves a combination of medications:
- Diuretics to help the kidneys remove excess fluid from the body, reducing swelling and easing the workload on the heart.
- ACE inhibitors to relax blood vessels and lower blood pressure.
- Beta-blockers to improve the heart’s pumping action over time.
- Digoxin to strengthen the force of the heart’s contractions.
Nutritional support is also a focus of care to ensure the child receives adequate calories for growth, which can be a challenge due to feeding difficulties. If the EFE is secondary to another condition, treatment will also be directed at that underlying cause.
For severe cases of EFE that do not respond to medical management, a heart transplant is the main treatment option. The prognosis for EFE has historically been poor, but outcomes have improved with advancements in medical therapy and transplantation. All individuals with EFE require lifelong monitoring by a cardiologist to manage their condition.