- Predominant biventricular diastolic dysfunction with lesser impairment of systolic performance.
- Symptomatic presentation:
- Chronic biventricular “backward failure” manifest as dyspnea and peripheral edema (often hepatomegaly and ascites).
- Reduced preload limits cardiac output (fatigue).
- Echocardiography: small stiff ventricles, preserved systolic function (until late stages), dilated atria and diastolic dysfunction by Doppler.
- Many disorders manifest restrictive “physiology” and must be excluded (eg, hypertrophic cardiomyopathy and constrictive pericarditis).
- Cardiac magnetic resonance imaging powerful: delineates myocardial infiltration, inflammation, and fibrosis and assesses pericardium, thereby helping establish underlying disorder.
- Tissue biopsy may be necessary for definitive diagnosis in some disorders (eg, amyloidosis).
Restrictive cardiomyopathies (RCM) are indolent disabling diseases resulting from pathophysiologic processes that induce predominant diastolic chamber dysfunction with lesser impairment of systolic performance. RCM is characterized by small stiff ventricles with progressive impairment of diastolic filling, leading to the hemodynamic conundrum of low preload but high filling pressures (Figure 24–1). This pattern of diastolic dysfunction leads to dilated atria and elevated mean atrial pressures, resulting clinically in biventricular “backward failure” manifest as pulmonary venous congestion (dyspnea) as well as systemic venous pressure elevation (peripheral edema). Systolic function is preserved in most cases, depending on the underlying cause (at least in the presenting stages of most of the underlying diseases). However, despite intact systolic function, the restrictive constraints on true ventricular preload limit stroke volume, thereby resulting in low cardiac output (fatigue) and ultimately hypoperfusion.
Pathophysiology of restrictive cardiomyopathy (RCM). CO, cardiac output; LA, left atrium; RA, right atrium; SOB, shortness of breath; SV, stroke volume.
The abnormal diastolic properties of the ventricle are typically attributable to abnormalities of the myocardium (infiltration, inflammation, or fibrosis) or the endomyocardial surface (inflammation and scarring). The RCM classification (Figure 24–2) may be most easily considered based on underlying pathophysiologic process as infiltrative (eg, amyloidosis), storage (eg, hemochromatosis), inflammatory (eg, hypereosinophilic syndrome), noninfiltrative (eg, diabetic), or idiopathic. Identification of specific infiltrative processes may have prognostic and therapeutic implications. Of note, secondary restrictive physiology can develop at a late stage in hypertrophic, dilated, valvular, hypertensive, and ischemic heart disease.
Classification of restrictive cardiomyopathies.
The vast majority of the underlying disease processes are slowly progressive, but by the time patients develop cardiac symptoms, the disease is advanced pathologically and heart failure progresses rapidly over a short period of time, and the majority die within a few years following diagnosis.
An appreciation of the physiology of the venous circulations and the dynamic effects of intrathoracic pressure (ITP) and respiratory motion on cardiovascular physiology is critical to understanding the hemodynamic pathophysiology of RCM and differentiating it from other conditions, particularly constrictive pericarditis (CP). Under physiologic conditions, venous return to both atria is biphasic, with a systolic peak determined by atrial relaxation (“X” descent ...