cardiovascular disorders
Cardiac Sarcoidosis
Introduction
Sarcoidosis is a multisystem, chronic inflammatory/granulomatous disorder that often affects the heart, causing conduction disturbances, bradyarrhythmias, tachyarrhythmias, and sometimes cardiomyopathy. Diagnosis is suspected in patients with known sarcoidosis or young patients who have otherwise unexplained heart block, arrhythmias, or cardiomyopathy. Treatment is corticosteroids and sometimes an implantable cardioverter-defibrillator (ICD). (See also Overview of Arrhythmogenic Cardiomyopathies and Sarcoidosis is reviewed elsewhere in THE MANUAL. This topic focuses on the cardiac effects of sarcoidosis. The inflammatory process in sarcoidosis leads to formation of noncaseating granulomas and fibrosis in any tissue. In cardiac sarcoidosis, the conducting system and/or myocardium are typically involved in patients with clinically apparent cardiac sarcoidosis, but valvular, papillary muscle, and pericardial involvement may also occur. Nearly all patients with cardiac sarcoidosis have involvement of other organs (typically the lungs), but cardiac sarcoidosis may rarely occur in isolation. About 25% of patients with systemic sarcoidosis have cardiac involvement identifiable using imaging techniques, but cardiac involvement is symptomatic in only about 20% of these (5% of all patients with sarcoidosis). The disorder shows marked regional variation in incidence being particularly high in people of Northern European and African descent, being particularly high in African-American women. The predilection of cardiac sarcoid involvement of the interventricular septum causes atrioventricular (AV) conduction system blocks in many patients with cardiac sarcoidosis. Involvement of the conducting system may cause first-, second-, or third-degree AV block, left anterior or left posterior hemiblock, and left or right bundle branch block. Involvement of the sinus node artery may produce the bradyarrhythmias of sinus nodal dysfunction. Myocardial involvement may produce tachyarrhythmias, predominantly ventricular tachycardia (VT), but atrial tachycardias, atrial flutter, and atrial fibrillation may also occur. Infiltration of the myocardium may cause an isolated left ventricular, an isolated right ventricular, a biventricular, dilated or Restrictive Cardiomyopathy . Pericardial involvement may cause pericardial effusion or contribute to restrictive physiology. Multifactorial Most patients with cardiac sarcoidosis are asymptomatic, but the associated bradyarrhythmias and tachyarrhythmias may cause palpitations, syncope, and sometimes cardiac arrest or sudden death. In most patients, disease manifests between the ages of 25 to 60 years. A significant number of deaths resulting from systemic sarcoidosis are due to sudden cardiac death, including in many patients who have had no previous indication of cardiac involvement. Cardiomyopathy may cause any heart failure symptom, including exertional dyspnea, fatigue, and peripheral edema. 