Cardiomyopathy caused by cardiac deposition of amyloid leading to decreased heart function (especially contractility).
Rare, estimated 2,000 new diagnosis per year in the United States.
Amyloidosis can be acquired or hereditary. Autosomal dominant for familial forms of amyloidosis more than 40 point mutations have been described. Also acquired secondary to multiple myeloma.
Amyloidosis is a heterogeneous disease that results from the deposition of toxic insoluble beta-sheet fibrillar protein aggregates in different tissues. Two main types of amyloidosis affecting the heart are (1) light chain amyloidosis—a clonal plasma cell disorder due to the overproduction and misfolding of antibody light chain fragments and (2) transthyretin amyloidosis (ATTR). Transthyretin is a tetrameric serum protein that is synthesized primarily by the liver. Accumulation of TTR causes cell toxicity and tissue death. ATTR occurs in two types: nonmutated (senile/wild type) or mutated transthyretin with autosomal dominant inheritance (familial type). Deposition of amyloid occurs in the myocardium, epicardium, and pericardium. Echocardiography classically shows a normal diastolic volume, slow ventricular filling throughout diastole, minimal shortening during systole, and high systolic volumes, resulting in a reduced stroke volume and low cardiac output state. The left ventricle is poorly compliant and left ventricular end-diastolic pressure is elevated. Consequently, endocardial perfusion is dependent on maintaining diastolic blood pressure. Localized septal deposition of amyloid protein may present clinically as hypertrophic obstructive cardiomyopathy. Infiltration of the conduction system may cause dysrhythmias and bundle branch block. Other forms of restrictive cardiomyopathy may be distinguished from cardiac amyloidosis by rapid ventricular filling early in diastole.
Clinical history and signs of cardiomyopathy. Echocardiographic findings and demonstration of amyloid on rectal or endocardial biopsy.
Evidence of cardiac amyloid is present in up to 90% of cases of primary and multiple myeloma-associated amyloidosis. Cardiac amyloidosis is also found in association with lymphoma, rheumatoid arthritis, tuberculosis, osteomyelitis, and bronchiectasis. The predominant clinical features are those of cardiac failure, tachypnea, orthopnea, decreased exercise tolerance, elevated jugular venous pressure, pulmonary edema, and hepatic distension. The ECG may show bundle branch block or rhythm abnormalities. The chest radiograph may show cardiomegaly (secondary to a pericardial effusion) or pleural effusions. The ventricular failure is often refractory to medical management. Treatment is heart and liver transplant in selected patients as survival generally poor 6 months to 4 years.
Precautions before anesthesia
Full medical history and physical examination to evaluate cardiac function and significance of any associated disorders. Proper evaluation of the restrictive nature of the cardiomyopathy must be obtained. Respiratory assessment and chest radiograph are mandatory. Cardiovascular assessment, ECG, and echocardiography should be performed prior to ...