Cardiology · Cardiomyopathy
The facts most likely to be tested
Restrictive cardiomyopathy presents with diastolic heart failure characterized by impaired ventricular filling and normal systolic function.
Amyloidosis is the most common cause of restrictive cardiomyopathy, often associated with low voltage EKG and periorbital purpura.
Sarcoidosis is a common infiltrative cause that frequently presents with atrioventricular block and conduction system abnormalities.
Endomyocardial fibrosis is a classic cause in tropical regions, often associated with hypereosinophilic syndrome.
Hemochromatosis causes restrictive cardiomyopathy due to iron deposition in the myocardium, often presenting with bronze skin and diabetes mellitus.
Kussmaul sign, an increase in jugular venous pressure during inspiration, is a hallmark physical exam finding in restrictive cardiomyopathy.
Endomyocardial biopsy remains the gold standard for confirming the specific etiology of infiltrative restrictive cardiomyopathy.
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A 68-year-old male presents with progressive dyspnea on exertion and lower extremity edema. Physical examination reveals elevated jugular venous pressure that increases with inspiration and clear lung fields on auscultation. An EKG shows low voltage QRS complexes in the limb leads. Echocardiography demonstrates biatrial enlargement and a speckled appearance of the myocardium with preserved ejection fraction. The patient has a history of monoclonal gammopathy of undetermined significance.
What is the most likely diagnosis?
Cardiac Amyloidosis
The combination of diastolic heart failure, low voltage EKG, and myocardial speckling is classic for amyloidosis, which is the most common cause of restrictive cardiomyopathy.
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Etiology / Epidemiology
Primary causes include amyloidosis, sarcoidosis, and hemochromatosis. Infiltrative processes lead to diastolic dysfunction with preserved systolic function.
Clinical Manifestations
Presents with right-sided heart failure symptoms. Look for Kussmaul sign and elevated JVP that does not decrease with inspiration.
Diagnosis
The endomyocardial biopsy is the gold standard. Echocardiogram shows biatrial enlargement and a restrictive filling pattern.
Treatment
Management is supportive. Use diuretics for volume overload. Avoid digoxin and calcium channel blockers in amyloidosis.
Prognosis
Poor prognosis with high risk of sudden cardiac death. Median survival is often < 2 years without transplant.
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Epidemiology & Etiology
Most common causes are infiltrative diseases like amyloidosis, sarcoidosis, and hemochromatosis. Radiation therapy and Loeffler endocarditis (hypereosinophilic syndrome) are also key etiologies. It is characterized by rigid ventricular walls that impede diastolic filling.
Pertinent Anatomy
The myocardium becomes stiff and non-compliant due to infiltration or fibrosis. This leads to biatrial enlargement as the atria struggle to fill the stiff ventricles. The ventricular wall thickness is often normal or increased, but the chamber size remains small.
Pathophysiology
Infiltration leads to diastolic dysfunction where the ventricles cannot relax, causing elevated filling pressures. This results in pulmonary and systemic venous congestion. Systolic function (ejection fraction) is typically preserved until late-stage disease.
Clinical Manifestations
Patients present with dyspnea, fatigue, and peripheral edema. Physical exam reveals Kussmaul sign (increased JVP with inspiration) and S3/S4 gallops. Syncope and arrhythmias are common red flags indicating advanced disease.
Diagnosis
The endomyocardial biopsy is the definitive diagnostic test. Echocardiogram demonstrates a restrictive filling pattern with biatrial enlargement. Cardiac MRI is highly sensitive for identifying infiltrative patterns like late gadolinium enhancement.
Treatment
Treatment is primarily symptomatic using diuretics to manage congestion. Digoxin and calcium channel blockers are contraindicated in amyloidosis as they may cause toxicity. Patients with refractory symptoms may require cardiac transplantation.
Prognosis
Prognosis is generally poor due to progressive heart failure and ventricular arrhythmias. Patients require close monitoring for sudden cardiac death. Survival is heavily dependent on the underlying etiology and response to therapy.
Differential Diagnosis
Constrictive Pericarditis: distinguished by pericardial knock and calcification on CXR
Hypertrophic Cardiomyopathy: distinguished by dynamic outflow tract obstruction
Dilated Cardiomyopathy: distinguished by reduced ejection fraction
Cardiac Tamponade: distinguished by Beck's triad and pulsus paradoxus
Cor Pulmonale: distinguished by primary pulmonary hypertension etiology