Constriction or restriction after mediastinal radiation
A 58-year-old woman with a history of mantle radiation for Hodgkin lymphoma presents with progressive dyspnea and lower-extremity edema. Echo: LVEF 60%, normal wall thickness, LA volume index 38 mL/m², moderate biatrial enlargement, pericardial thickness 5 mm without effusion. Mitral inflow E/A 1.6, deceleration time 160 ms. Septal e' 12 cm/s, lateral e' 7 cm/s. Mitral E velocity falls 28% with inspiration. TR peak velocity 3.1 m/s. Hepatic vein Doppler shows expiratory diastolic flow reversal. IVC is dilated and non-collapsing.
1. Interpret the annular velocities and respirophasic change. Why does annulus reversus occur in constriction?
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Normally lateral e' exceeds septal e' by about 10%. Here septal e' (12 cm/s) exceeds lateral e' (7 cm/s), which is annulus reversus. In constrictive pericarditis, the thickened or adherent pericardium tethers the lateral mitral annulus, reducing its longitudinal excursion, while the septal annulus is relatively spared and may show compensatory increased motion. This reverses the normal septal-lateral relationship.
The 28% inspiratory fall in mitral E velocity exceeds the usual 25% threshold and reflects ventricular interdependence: inspiration increases right-heart filling and shifts the septum leftward, reducing left-heart filling and mitral inflow; expiration does the opposite. Hepatic vein expiratory diastolic flow reversal is another sign of constrained right-heart filling. Together these findings favor constriction.
2. How would you differentiate constrictive pericarditis from restrictive cardiomyopathy at the bedside and with echo? What maneuvers?
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Constrictive pericarditis: pericardial thickening or calcification, respirophasic septal bounce, annulus reversus, preserved or increased septal e', hepatic vein expiratory reversal, dilated non-collapsing IVC, and >25% respiratory variation in mitral or tricuspid inflow. Restrictive cardiomyopathy: biatrial enlargement with low e' at both annuli, no significant respirophasic variation, no pericardial thickening, and often symmetric LV thickening or infiltrative features. Maneuvers: record mitral and tricuspid inflow during quiet respiration and ask the patient to sniff or perform a Valsalva; in constriction, respiratory variation is exaggerated and may persist, while in restriction it is blunted. Sitting or standing can also reduce venous return and unmask constriction. If doubt remains, invasive simultaneous right- and left-heart pressure recordings showing discordance are definitive.
3. What are the limitations of echo in this setting, and what confirmatory tests would you order?
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Echo is limited because radiation can produce mixed constrictive and restrictive disease, pericardial thickness may be normal in up to 20% of constriction, and respiratory variation can be affected by breathing pattern, TR, and atrial fibrillation. Annulus reversus is supportive but not specific. Confirmatory tests: cardiac MRI with late gadolinium and pericardial mapping, CT for pericardial calcification, and right/left heart catheterization to demonstrate ventricular discordance and enhanced interventricular dependence. Also screen for radiation-induced coronary disease and valvular disease. The final decision about pericardiectomy should integrate symptoms, imaging, and hemodynamics.