Cardiac amyloidosis

Cardiac amyloidosis is a subcategory of amyloidosis where there is the depositing of the protein amyloid in the cardiac muscle and surrounding tissues. Amyloid, a misfolded and insoluble protein, can become a deposit in the heart’s atria, valves, or ventricles. These deposits can cause thickening of different sections of the heart, leading to decreased cardiac function. The multisystemic disease was often misdiagnosed, with diagnosis previously occurring after death during the autopsy. However, recent advancements of technologies have increased the diagnosis of the disease. This disease has multiple types including light chain, familial, and senile. One of the most studied types is light chain cardiac amyloidosis. The prognosis depends on the extent of the deposits in the body and the type of amyloidosis. Cardiac amyloidosis is a subcategory of amyloidosis where there is the depositing of the protein amyloid in the cardiac muscle and surrounding tissues. Amyloid, a misfolded and insoluble protein, can become a deposit in the heart’s atria, valves, or ventricles. These deposits can cause thickening of different sections of the heart, leading to decreased cardiac function. The multisystemic disease was often misdiagnosed, with diagnosis previously occurring after death during the autopsy. However, recent advancements of technologies have increased the diagnosis of the disease. This disease has multiple types including light chain, familial, and senile. One of the most studied types is light chain cardiac amyloidosis. The prognosis depends on the extent of the deposits in the body and the type of amyloidosis. The formation of amyloid is due to these free light chains circulating through the body, caused by abnormal clones of plasma cells overproducing monoclonal immunoglobulin lambda light chains. This type usually affects males over the age of 60 and is rapidly progressive. Diagnostic tests includes serum and urine electrophoresis, laboratory testing for the determination of elevated levels of troponin and BNP, and ECGs showing low QRS voltages. This type is caused by mutations of proteins involved in amyloid formation, including transthyretin (TTR), fibrinogen, apolipoprotein A1, or apolipoprotein A2. A common mutation is the TTR gene mutation Val122Ile. This type of amyloidosis can be identified by genetic testingfor protein mutation. Familial amyloidosis symptoms are centered around neuropathological and cardiac problems. This type is considered the wild-type mutation which leads to the development of TTR deposits. It usually affects males over 70 years with the manifestation of carpal tunnel syndrome. This type is often misdiagnosed, however, greater use of cardiac magnetic resonance has increased diagnosing rates. Amyloid deposition in the heart can cause both diastolic and systolic heart failure. Symptoms of cardiac amyloidosis include dyspnea on exertion, peripheral edema, ascites, thromboembolisms, and symmetric, sensory neuropathy, postural hypotension, periorbital bleeding, pericardial effusion, atrial arrhythmia, first/second degree heart blocks, atrial fibrillation, syncope, elevated neck veins and jugular venous pressure. For patients with light-chain amyloidosis, there is possibility of macroglossia, periorbital bruising, and loss of the third and fourth heart sound. The general cause of cardiac amyloidosis is misfolding of a specific protein precursor depending on the amyloidosis type. Protein precursors include immunoglobulin-derived light chains and transthyretin mutations. The misfolding of the protein causes it to have insoluble beta-pleated sheets, creating an amyloid. Amyloid, the aggregation, or clumping, of proteins, is resistant to degradation by the body. Amyloids are mostly fibrils, while also containing a P component, apolipoprotein, collagen, fibronectin, and laminin. The P component, a pentameric protein, stabilizes the fibrils of the amyloid, which reduces their clearance from the body. Deposits of the amyloids can occur through out of the body, including the heart, liver, kidneys, spleen, adrenal glands, and bones. Deposits in the extracellular cardiac space can stiffen the heart, resulting in restriction of the ventricles. Echocardiography is used to provide an assessment of the heart’s function. Amyloidosis presents with ventricle and valvular thickening, biatrial enlargement, restrictive filling pattern, with normal to mildly reduced systolic function and decreased diastolic filling.