Restrictive Cardiomyopathy - Stanford University



Restrictive Cardiomyopathy

Introduction

-Definition: Heart muscle disease resulting in impaired ventr filling with decr diastolic volume

-ventricular walls are excessively rigid and impede ventricular filling

-Systolic function usually normal; wall thickness may be normal-increased

-hallmark increased stiffness of myocardiam: rise in ventricular vol -> precipitous rise pressure

-can affect either or both ventricles, usually right sided failure predominates

Diagnosis

- suspected when heart failure present but no systolic dysfunction

- symptoms typical of heart failure, but cardiomegally typically absent

- Kussmaul’s sign – jugular venous pulse may rise during inspiration

- Hemodynamics Characteristics -

1. Rapid early decline in Ventricular Pressure at onset of diastole

2. Early diastolic filling (high atrial Press as AV opens)

Ventricular Tracing: Square root sign

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Atrial Tracing: rapid x and y descents present; most prominent wave is y descent (tric open)

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Differentiating Constrictive Pericarditis

-distinction must be made because management dramatically different

-often very difficult to make distinction

-hemodynamic parameters same

-clinical history suggestive of pericarditis or TB makes constrictive peric more likely

-no single diagnostic technique reliable, may resort to pericardiectomy

-Echo: pericardial thickening; Cath: RVSP usu < 50

Pathogenesis

Amyloidosis

-Outside of the tropics, most common cause of restrictive CMP

-Cardiac amyloid usually a/w primary amyloid – overprod light chains by plasma cells in MM

-Secondary amyloid caused by deposition of other proteins (familial, senile, inflammatory dz)

-Restrictive CMP due to tissue injury 2/2 replacement of normal myocardium by interstit deposits

-May result in thickened wall without cavity dilatation

-Amyloid deposits in SA/AV nodes -> heart block

-Granular, sparkling appearance on Echo is characteristic, not diagnostic

-Diagnosis made with endomyocardial biopsy tissue/immunohistochemical staining

Endomyocardial Fibrosis

-Most common cause worldwide; endemic in Africa/India/S. America/Asia

-Restrictive obliterative CMP a/w eosinophlia

-Intracytoplasmic granular contect of eos responsible

Idiopathic Restrictive Cardiomyopathy

-Sometimes familial, associated with distal skeletal myopathy and AV block

-Characterized by mild-moderate increase in cardiac weight

-Patchy endocardial fibrosis present; fibrosis of SA and AV nodes lead to CHB

Other infiltrative/storage dz: Gaucher’s, Hurler’s (mucopolysaccharide), Fabry’s (glycosphingolipid), Sarcoid

Other Restrictive Conditions: carcinoid (fibroblast proliferation), antrhacyclines, XRT

Treatment

-Maintain ventricular filling pressures

-Judicious use of diuretics for venous congestion / avoid nitrates

-Digoxin use with caution; arrhythmogenic in amyloidosis

-loss of atrial kick detrimental – maintain sinus (amio/DCCV/pacing)

-anticoagulation warranted due to propensity of thrombus formation in atrial appendage

-Amyloid: Median survival 2yrs; chemo dramatic benefits; transplant (recurrence can occur)

-Endomyocardial Fibrosis – steroids; if fibrotic, surgical excision of endocardium/valve replace

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