Amyloidosis is a condition characterized by the accumulation of abnormal, misfolded proteins in various organs. When these amyloid deposits settle in the heart muscle, the condition is referred to as cardiac amyloidosis. The stiffening of the heart muscle impairs its ability to pump blood effectively, leading to a range of cardiac symptoms. Over time, this process can disrupt the heart’s normal function, causing it to struggle with both relaxing to fill with blood and contracting to pump it out.
The Role of Echocardiography in Diagnosis
An echocardiogram, often simply called an echo, is a type of ultrasound specifically for the heart. It uses high-frequency sound waves to create detailed, moving images of the heart’s chambers, valves, walls, and blood vessels. This technology provides a comprehensive view of the heart’s structure and function.
When cardiac amyloidosis is suspected, an echocardiogram is frequently one of the first and most important diagnostic tools used. The procedure is non-invasive, meaning it does not require any incisions or instruments to be inserted into the body. It also does not use ionizing radiation, making it a safe option for repeated examinations if needed. The widespread availability of echocardiography makes it a practical choice for many healthcare facilities.
Key Echocardiographic Features
One of the most apparent signs on an echocardiogram suggestive of cardiac amyloidosis is a noticeable increase in the thickness of the ventricular walls. The lower chambers of the heart, the ventricles, appear thickened, a state sometimes called pseudo-hypertrophy. This thickening is not due to an increase in actual heart muscle cells, as seen in athletes or in response to high blood pressure, but rather from the infiltration of amyloid protein deposits.
Another classic finding is a “granular sparkling” or “speckled” appearance of the heart muscle on the ultrasound image. This texture is caused by sound waves reflecting off the dense amyloid deposits scattered throughout the myocardium. When observed, especially in conjunction with other features, this sparkling texture is a strong indicator of amyloid infiltration.
The pressure dynamics within the heart are also altered, leading to visible changes in chamber size. The upper chambers, or atria, often become enlarged. This occurs because the stiff ventricles struggle to accept blood, causing a backup of pressure that stretches the atrial walls. Other observations may include a slight buildup of fluid around the heart, known as a pericardial effusion, and thickening of the heart valves.
Assessing Heart Function with Advanced Echo Techniques
Beyond observing the heart’s structure, an echocardiogram provides deep insights into how the heart is functioning, which is particularly revealing in cases of cardiac amyloidosis. The primary functional problem in this condition is diastolic dysfunction. This means the heart muscle has lost its ability to relax properly between beats, which impairs the ventricles’ capacity to fill with blood efficiently. An echo can measure blood flow patterns between the chambers to quantify the severity of this relaxation abnormality.
A more advanced technique used to assess heart function is strain imaging, specifically the measurement of global longitudinal strain (GLS). This technology tracks the deformation of the heart muscle during a contraction. It analyzes the myocardium segment by segment to detect subtle functional impairments that might not be visible with standard ejection fraction measurements, which can remain normal until late in the disease.
In cardiac amyloidosis, strain imaging often reveals a very distinctive pattern of dysfunction known as “apical sparing.” In this pattern, the muscle function at the base and middle of the left ventricle is severely reduced, while the function at the very tip, or apex, remains relatively normal. This creates a visual on the strain map that is often described as a “cherry on top.”
This apical sparing pattern is a powerful clue for diagnosing cardiac amyloidosis because it is not typically seen in other conditions that cause thickened heart walls, such as hypertrophic cardiomyopathy or hypertensive heart disease. The presence of this specific strain pattern significantly increases the likelihood of cardiac amyloidosis and prompts further investigation.
Confirming the Diagnosis After an Echo
While the findings on an echocardiogram are highly suggestive of cardiac amyloidosis, they do not provide a definitive diagnosis alone. An echo is a screening tool that identifies patients who require further, more specific testing to confirm the presence of amyloid and to identify the exact type of protein involved. Distinguishing between types, such as AL (light-chain) and ATTR (transthyretin), is necessary as treatments differ significantly.
To confirm the diagnosis, physicians turn to a range of other tests. A cardiac MRI (CMR) can also visualize the heart and may show characteristic patterns of tissue changes after the injection of a contrast agent, further supporting the diagnosis. For transthyretin (ATTR) amyloidosis, a nuclear imaging test known as a PYP scan is highly accurate. This scan uses a radioactive tracer that is taken up by ATTR amyloid deposits, causing the heart to “light up” on the images.
In some cases, a biopsy may be required, especially when AL amyloidosis is suspected or the diagnosis remains uncertain. This involves taking a tissue sample from an accessible area, like abdominal fat, to look for amyloid. If that is inconclusive, an endomyocardial biopsy, where a tiny piece of heart muscle is removed for analysis, may be performed as it remains the gold standard for confirming the diagnosis and typing the amyloid protein.