What are the hemodynamic findings of restrictive cardiomyopathy?

Hemodynamic Findings of Restrictive Cardiomyopathy

Restrictive cardiomyopathy is characterized by a distinctive hemodynamic profile featuring markedly elevated ventricular filling pressures with normal or near-normal ventricular volumes, resulting in a steep pressure-volume relationship where small increases in volume lead to exaggerated increases in diastolic pressure. 1

Key Hemodynamic Features

Ventricular Pressure Patterns

• Characteristic "dip and plateau" or "square root" pattern in ventricular diastolic pressure tracings, reflecting impaired ventricular filling 2
• Markedly elevated left ventricular end-diastolic pressure (LVEDP), typically >18-30 mmHg 2, 3
• Elevated right ventricular end-diastolic pressure (RVEDP), though usually lower than LVEDP 2
• Rapid early diastolic pressure rise with a characteristic "dip and plateau" pattern for early diastolic LV pressure changes 2

Atrial Pressure Patterns

• M- or W-shaped atrial pressure waveforms 2
• Elevated filling pressures in all four cardiac chambers 2
• Attenuated or absent Y-descent in right atrial pressure waveform (similar to cardiac tamponade) 2

Ventricular Volumes and Function

• Normal or reduced ventricular chamber sizes 2
• Normal ventricular ejection fraction in most cases (preserved systolic function) 2, 1
• Biatrial enlargement due to chronically elevated ventricular filling pressures 2

Echocardiographic Findings

Mitral Inflow Patterns

• Restrictive filling pattern with E/A ratio >2.5 2
• Shortened deceleration time (DT) of E velocity <150 msec 2
• Shortened isovolumic relaxation time (IVRT) <50 msec 2

Tissue Doppler Findings

• Decreased septal and lateral e' velocities (3-4 cm/sec) 2
• Higher lateral e' compared to septal e' velocity (unlike constrictive pericarditis which shows "annulus reversus") 2
• Elevated E/e' ratio >14, indicating increased left atrial pressure 2

Other Echocardiographic Parameters

• Markedly increased left atrial volume index (>50 mL/m²) 2
• Pulmonary vein flow showing reduced S/D ratio 2
• Possible mid-diastolic flow (L velocity) due to slow LV relaxation and increased left atrial pressure 2

Differentiating from Constrictive Pericarditis

• In restrictive cardiomyopathy, pulmonary artery systolic pressures are often elevated, whereas they are usually normal in constrictive pericarditis 2
• Respiratory variation in ventricular filling is less pronounced in restrictive cardiomyopathy compared to constrictive pericarditis 2
• Systolic area index (ratio of right ventricular to left ventricular systolic pressure-time area during inspiration versus expiration) helps differentiate the two conditions 2
• In restrictive cardiomyopathy, lateral e' is higher than septal e', whereas in constrictive pericarditis, septal e' is often higher than lateral e' (annulus reversus) 2

Clinical Implications

• Grade 3 diastolic dysfunction is typically present in advanced restrictive cardiomyopathy and is associated with poor outcomes 2
• The hemodynamic profile reflects increased myocardial stiffness due to various pathological processes including interstitial fibrosis, infiltration, or storage disorders 1
• These hemodynamic findings translate clinically to symptoms of dyspnea, fluid retention, and fatigue due to impaired cardiac output reserve 2

Pitfalls in Diagnosis

• Differentiation from constrictive pericarditis can be challenging and may require invasive hemodynamic assessment 2
• The restrictive filling pattern on echocardiography must be interpreted in clinical context, as it can occur transiently in other conditions 2
• Multiple imaging modalities including echocardiography, cardiac MRI, and cardiac catheterization may be necessary for definitive diagnosis 1
• Normal or mildly increased wall thickness does not exclude restrictive cardiomyopathy 2, 1