Bit · Cardio
Restrictive vs Constrictive cardiomyopathy / pericarditis
Two causes of right-sided heart failure with preserved systolic function that produce nearly identical clinical pictures. The pivot is whether the problem is in the myocardium or the pericardium.
Mechanism
Both result in impaired diastolic filling with preserved ejection fraction, elevated jugular venous pressure, hepatomegaly, ascites, and lower-extremity edema. Distinguishing them matters because constrictive pericarditis is potentially curable surgically (pericardiectomy):
- Restrictive cardiomyopathy — the myocardium is stiff. Causes: amyloidosis (most common in clinical practice), sarcoidosis, hemochromatosis, endomyocardial fibrosis, Loeffler endocarditis, radiation, scleroderma, post-radiation, glycogen storage disease (Pompe). Echo shows biatrial enlargement, normal ventricular cavity size, and on tissue Doppler — reduced mitral annular tissue velocity (e').
- Constrictive pericarditis — the pericardium is thickened/calcified, encasing the heart. Causes: post-cardiac surgery, post-radiation, TB (globally most common), uremia, post-viral. Echo shows pericardial thickening; respiratory variation in ventricular filling is characteristic. Preserved mitral annular velocity. Pericardial knock on auscultation.
Differentiator Table
| Restrictive CMP | Constrictive pericarditis | |
| Where is the problem? | Stiff myocardium | Stiff/thickened pericardium |
| Kussmaul sign (JVP ↑ on inspiration) | May be present | Classically present |
| Pericardial knock | Absent | Present (early diastolic) |
| Pulsus paradoxus | Less common | May be present |
| Echo — pericardium | Normal thickness | Thickened, calcified, often pericardial effusion early |
| Echo — atrial size | Biatrial enlargement | Normal or mild |
| Tissue Doppler — septal e' (mitral annulus) | DECREASED (myocardium itself is bad) | PRESERVED or INCREASED (myocardium is OK, just constrained) |
| Respiratory variation in ventricular inflow | Minimal | Marked (ventricular interdependence) |
| BNP | Markedly elevated (myocardial stress) | Mildly elevated |
| Cardiac MRI | Myocardial infiltration (e.g. late gadolinium in amyloid) | Thick pericardium, septal bounce |
| Classic causes | Amyloid, sarcoid, hemochromatosis, Loeffler, radiation | TB, post-cardiac surgery, post-radiation, uremia |
| Treatment | Treat underlying disease; supportive | Pericardiectomy (often curative) |
The Pivot
The most discriminating finding is on echo:
- Tissue Doppler septal e' velocity preserved? → constrictive pericarditis (the myocardium is fine, just squeezed).
- Reduced e' velocity? → restrictive cardiomyopathy.
Confirm with cardiac MRI: a thick pericardium nails constrictive; myocardial infiltration nails restrictive (amyloid has distinctive late gadolinium enhancement).
NBME-Style Stem
A 64-year-old man with a history of mantle radiation for Hodgkin lymphoma 20 years ago presents with progressive lower-extremity edema, ascites, and dyspnea. JVP is elevated and rises with inspiration. An early diastolic high-pitched sound is heard at the apex. Echocardiography shows a thickened, calcified pericardium and preserved tissue Doppler velocities at the mitral annulus. Which of the following is the most likely diagnosis?
Concept Anchor
Both diseases shrink the ventricle's diastolic room — but in restriction the heart muscle is the problem (tissue Doppler suffers), while in constriction the pericardium is the cage (tissue Doppler is preserved). That one velocity decides which is reversible by surgery.