Understanding Infiltrative Cardiomyopathy
Infiltrative cardiomyopathy is a condition where abnormal substances accumulate within the heart muscle, known as the myocardium. This buildup causes the heart muscle to become stiff and less flexible. This infiltration impairs the heart’s normal function, making it difficult for the heart to pump blood effectively throughout the body.
These deposited materials disrupt the heart’s ability to contract and relax rhythmically. They can interfere with electrical signals that coordinate heartbeats and reduce the muscle’s ability to stretch and fill with blood, leading to a progressive decline in performance.
The heart muscle may struggle to relax properly, hindering its ability to fill with blood between beats, a condition known as diastolic dysfunction. As the disease advances, the heart’s capacity to eject blood with sufficient force, or systolic function, may also be compromised. These changes diminish the heart’s efficiency, impacting its capacity to meet the body’s circulatory demands.
The abnormal substances can also interfere with the heart’s electrical conduction system, leading to various rhythm disturbances. The heart muscle becomes less compliant, meaning it cannot easily expand to accommodate blood, which can lead to increased pressure within the heart chambers.
Common Underlying Causes
Several distinct diseases can lead to infiltrative cardiomyopathy by depositing different substances within the heart muscle.
Amyloidosis involves the deposition of abnormal protein fibrils, called amyloid, into various organs, including the heart. These deposits make the heart muscle rigid. Common types affecting the heart include light chain (AL) amyloidosis and transthyretin (ATTR) amyloidosis, which can be hereditary or acquired.
Sarcoidosis is a systemic inflammatory disease causing granulomas, small clumps of inflammatory cells, in different organs. When these develop in the heart, they disrupt its structure and electrical activity.
Hemochromatosis, a disorder of excessive iron absorption, leads to iron accumulation in the heart muscle, causing damage and impairing its pumping ability.
Fabry disease, a genetic disorder, results from the buildup of a specific fatty substance called globotriaosylceramide within heart cells. This lipid accumulation can lead to thickening of the heart walls and impaired function. These conditions are systemic disorders where the heart is one of several organs affected by abnormal substance deposition.
Recognizing Signs and Diagnosis
Individuals with infiltrative cardiomyopathy often experience symptoms as heart function declines. Common complaints include shortness of breath, which may worsen with exertion or when lying flat, due to fluid backing up into the lungs. Swelling in the legs, ankles, or abdomen (edema) can also occur as the heart struggles to pump blood efficiently, leading to fluid retention.
Fatigue is a frequent symptom, resulting from the heart’s reduced ability to deliver oxygenated blood. Some individuals may also experience chest pain or heart palpitations, sensations of a rapid or pounding heart.
Diagnosing infiltrative cardiomyopathy typically involves a combination of tests. An electrocardiogram (ECG or EKG) can reveal abnormalities like low voltage or irregular heart rhythms. An echocardiogram provides detailed images of the heart’s structure and function, often showing thickened heart walls and impaired filling.
Cardiac magnetic resonance imaging (CMR) is valuable for identifying specific patterns of infiltration. A definitive diagnosis often requires a biopsy, either of the heart muscle or other affected organs, to identify the specific infiltrating substance. Genetic testing may also be performed when hereditary forms are suspected.
Treatment and Long-Term Outlook
Treatment for infiltrative cardiomyopathy primarily focuses on addressing the underlying cause and alleviating heart failure symptoms. For AL amyloidosis, specific chemotherapy regimens may reduce abnormal protein production. Iron chelation therapy helps remove excess iron in hemochromatosis.
For cardiac sarcoidosis, immunosuppressants like corticosteroids are often prescribed to reduce inflammation. In Fabry disease, enzyme replacement therapy (ERT) can reduce fatty substance accumulation. The choice of treatment depends on the specific infiltrating substance identified.
Managing heart failure symptoms is also important. Diuretics are commonly used to reduce fluid retention and alleviate swelling and shortness of breath. Other heart failure medications, such as beta-blockers or ACE inhibitors, might be used cautiously to support heart function. Arrhythmias may require antiarrhythmic drugs, pacemakers, or implantable defibrillators to stabilize heart rhythm.
In advanced stages, more intensive therapies may be considered. These can include supportive devices like ventricular assist devices (VADs), which help the heart pump blood, or heart transplantation. The long-term outlook varies, influenced by the underlying cause, diagnosis stage, and treatment response. Ongoing medical care and lifestyle adjustments, such as a low-sodium diet and fluid management, are important for optimizing outcomes.