Amyloidosis and the Heart - Causes, Symptoms, Diagnosis and Treatment.

Introduction

Amyloidosis is a systemic infiltrative disease with extracellular deposition of insoluble proteins. Cardiac amyloidosis is one of the leading causes of restrictive cardiomyopathy and underdiagnosed leading entities. There is rapid progressive diastolic dysfunction in a non-dilated ventricle. A high degree of suspicion is required to diagnose cardiac amyloidosis. It is one of the leading causes of mortality in patients with systemic amyloidosis. It can be manifested primarily or also be discovered in patients incidentally with the other signs and symptoms of systemic amyloidosis. The diagnosis can be delayed in cardiac amyloidosis, which is common, and this will lead to a delay in the initiation of the treatment.

What Is Cardiac Amyloidosis?

Cardiac amyloidosis is a disorder due to the deposits of abnormal protein in the heart tissue and these deposits will make it hard for the heart to pump blood and, therefore, it will pump harder. This will damage and weaken the heart, causing it to fail. It is also known as stiff heart syndrome or senile amyloidosis.

What Causes Cardiac Amyloidosis?

Amyloidosis is a disease that occurs due to amyloid buildup in the body tissues, which are clumps of proteins. These proteins will replace normal tissue over time, leading to the organ's failure. There are different forms of amyloidosis. Cardiac amyloidosis will occur when the amyloid deposition takes the place of normal heart muscle, and it is the most typical type of restrictive cardiomyopathy. The way the electrical signals move through the heart can be affected by cardiac amyloidosis, leading to abnormal heartbeats, arrhythmias, and faulty signals that cause heart block. Familial cardiac amyloidosis is when the condition is inherited. Sometimes, it can also develop due to another disease, such as type of bone and blood cancer or other medical problems that cause inflammation. Cardiac amyloidosis is more common in men compared to women, and the disease is rare in individuals under 40 years.

What Are the Symptoms of Cardiac Amyloidosis?

The symptoms of cardiac amyloidosis will typically involve the heart and other vital organs, such as the liver and kidney. The possible symptoms that are severe in the end stages of cardiac amyloidosis are:

• Shortness of breath during activities or while lying down.

• Fluid accumulation in the feet, ankles, legs, and abdomen will lead to swelling.

• Fatigue for extended days or more.

• Heart palpitations.

• Enlarged neck veins happen due to heart failure as the heart is struggling to pump hard enough. There is too much pressure due to extra effort on the veins in the neck, which will cause them to get bigger.

• There is swelling of the liver, known as hepatomegaly.

• There is inflammation of the kidneys and changes in the kidney's functioning, which is ineffective.

Signs of cardiac amyloidosis that do not involve the heart, liver, or kidneys are:

• Swelling in the tongue.

• Unusual bruising.

• Carpal tunnel syndrome.

• Lumbar spinal stenosis is a narrowing in the space around the lower spine.

• Hearing and eye problems.

• Numbness or tingling in the arms or legs.

How Is Cardiac Amyloidosis Diagnosed?

Based on a combination of factors such as symptoms, physical examination of the body, and family history, healthcare providers will suspect cardiac amyloidosis. Then, various diagnostic tests, lab tests, and imaging are done to confirm or rule out cardiac amyloidosis.

The various lab tests for diagnosing cardiac amyloidosis are blood, tissue, or other bodily fluid samples. A specific dye known as Congo red will make the amyloid glow green under certain types of lighting.

• Tissue Biopsy: The healthcare provider takes a small tissue sample from the heart muscle for lab testing. Tissue samples can also be taken from other places, but imaging test confirmation might be required if a non-heart sample has a positive result.

• Blood Testing: These tests can detect the circulating proteins, as certain types of cardiac amyloidosis involve amyloid proteins circulating in the blood.

• Urine Testing: Amyloid proteins can be present in urine in certain conditions. The condition can be diagnosed by testing the urine for those proteins.

What Are Imaging Tests for Cardiac Amyloidosis?

The condition can be diagnosed with the help of imaging tests because cardiac amyloidosis can cause the heart to enlarge and change its shape. Possible tests are echocardiogram, scintigraphy, Magnetic Resonance Imaging (MRI), and electrocardiogram.

• Echocardiogram: Ultra-high-frequency sound waves are used in this test, and sound-emitting devices are held against the skin of the chest. Medical providers can see the heart because of how sound waves bounce and reflect off different structures inside the body. This test shows certain thick parts of the heart, a vital symptom of this condition.

• Scintigraphy: A tracer is injected into the blood by the medical provider for this test, and this substance is slightly radioactive and not harmful. The tracers will accumulate in areas with amyloid accumulation, and these spots are effortless to see on the imaging tests known as Single-Photon Emission Computed Tomography (SPECT) scans.

• Magnetic Resonance Imaging: Extremely powerful magnets and computer processing to generate an image of the heart are used in this test. Magnetic resonance imaging is detailed extremely, allowing healthcare providers to see the thickening or other relevant changes in the heart’s structure.

• Electrocardiogram: Several sensors are used by the electrocardiogram that sticks to the skin of the chest. The sensors detect the electricity traveling through the heart and display the strength of the electric current on a paper printout or a screen display. Doctors or trained experts analyze the unusual changes in the waves.

How Is Cardiac Amyloidosis Treated?

Healthcare providers will be instructed to make a few changes in the diet to limit the intake of salts and fluids. To get rid of excess fluid from the body, there is a need to take water pills. In individuals with atrial fibrillation, medications such as digoxin, beta-blockers, and calcium channel blockers can be taken. It is essential to monitor the dosage of the drug carefully and also use it with caution.

Other treatment options are:

• Implantable cardioverter-defibrillator (AICD).

• Chemotherapy.

• Drugs that will target the abnormal proteins.

• Pacemaker, if there are heart signal problems.

• An anti-inflammatory medicine - Prednisalone.

What Are the Complications for Cardiac Amyloidosis?

The possible complications are:

• Sick sinus syndrome.

• Symptomatic cardiac conduction system disease.

• Low blood pressure and dizziness due to excessive urination.

• Increased sensitivity to digoxin.

• Fluid buildup in the abdomen.

• Congestive heart failure.

• Atrial fibrillation or ventricular arrhythmias.

Conclusion

Cardiac amyloidosis is the build-up of abnormal proteins in the heart. It can be treated with medications, and dietary modifications, and sometimes heart and/or liver transplantation might be necessary. It also involves cardiovascular medicine, cardiomyopathy, and inherited cardiovascular disease programs.