Pathophysiology and hemodynamics
Normally, the pericardium moves synchronously with the myocardium, but with thickening of the layers, this ability is completely lost. The rigid pericar-dial sac isolates the heart from normal intrathoracic pressure fluctuations during respiration.
The key factor in hemodynamic disorders is the decrease in compliance (compliance) of the pericardium, rather than simply its anatomical thickening. Pronounced ventricular coupling occurs: a change in volume or pressure in one ventricle directly affects the opposite one. Due to the inability to expand normally during diastole, early diastolic filling occurs, which abruptly halts mid-diastole, and the filling pressures in all four chambers equalize.
Etiology and clinical presentation
Although the disease may be idiopathic, the most common causes in modern practice are the consequences of cardiac surgery and prior radiotherapy (radiotherapy). Less commonly, constriction is caused by uremia, systemic connective tissue diseases, subclinical viral infections, and neoplasms. Tuberculosis etiology is currently extremely rare.
Symptoms are caused by low cardiac output and the development of right ventricular failure. Patients complain of shortness of breath (dyspnoea), orthopnea, and severe fatigue. Physical examination reveals signs of severe venous congestion: liver enlargement (hepatomegaly) and ascites.
Sometimes occult constriction (occult constriction) is encountered, in which there are no symptoms under normal conditions, but they manifest during a sudden fluid balance disturbance.
Diagnostic Imaging: CT and MRI
Computed tomography and magnetic resonance imaging play a decisive role in visualizing the pathology. Thickening is usually localized along the free wall of the right ventricle and at the level of the atrioventricular junction.
- CT (Computed Tomography): The method of choice for detecting pericardial calcification. It allows precise assessment of the localization and thickness of calcium deposits.
- MRI (Magnetic Resonance Imaging): Superior to CT in differentiating thickened pericardial layers from effusion (fluid). The fibrous or calcified pericardium appears hypointense on T1- and T2-weighted images.
The altered filling pattern on tomograms leads to the appearance of tubular ventricular morphology (usually the right) with secondary dilatation of the atria, inferior vena cava, and hepatic veins.
Echocardiography and radiography
On chest radiography, straightening of the cardiac borders, dilatation of the superior vena cava and azygos vein, and left atrial enlargement can be noted. In 40–50% of patients, plaque-like or linear calcifications are visible.
Echocardiography reveals:
- Abnormal motion of the interventricular septum (bulge inversion or diastolic flattening).
- Dilatation of the inferior vena cava, which practically does not collapse during inspiration.
- Increased respiratory variability of blood flow (right ventricular filling increases on inspiration, left ventricular filling on expiration).
Transesophageal echocardiography provides better visualization than transthoracic, allowing a more accurate assessment of pericardial thickening.
Differential diagnosis
The nonspecificity of symptoms requires the exclusion of pulmonary hypertension, myocardial infarction, and, most importantly, restrictive cardiomyopathy (RCM).
Differentiation from restriction is critically important for patients (especially after radiation therapy) because treatment approaches differ radically: constriction requires surgery (pericardiectomy), while restrictive forms are treated with medical therapy. MRI accuracy in this differentiation reaches 93%.
Remember the metaphor of the "heart in a shell": a rigid fibrous or calcified framework prevents the heart from expanding in diastole. The ventricles cannot accept blood, so it accumulates in the veins — hence inferior vena cava dilatation, hepatomegaly, and ascites.
What else to study on this topic
- Assessment of functional pericardial rigidity using Cine-MRI
- "Serpentine septal motion" phenomenon of the interventricular septum
- Late gadolinium enhancement to detect active inflammation
- Tumor lesions of the pericardium: mesotheliomas, sarcomas, and metastases
- Ventricular coupling: pathophysiological mechanisms
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