Constrictive Pericarditis vs Restrictive Cardiomyopathy

Constrictive pericarditis is caused by adhesions between the visceral and parietal layers of the pericardium. It most commonly occurs following cardiac surgery, radiation therapy, or pericarditis of any etiology. Uremic and viral pericarditis are more common in the west, while tuberculous pericarditis remains popular in the developing world.

Eggshell Calcification of the pericardium is suggestive of Constrictive pericarditis, but its absence does not rule out constrictive pericarditis. Thick, shaggy, and amorphous calcifications are typical of tuberculous pericarditis.

Demonstration of pericardial adhesions can be done on MRI cine gradient echo images with tag lines applied perpendicular to the pericardium. In normal pericardium, these lines, which are placed during systole, break on cine images. In constrictive pericarditis, on the other hand, adhesions keep the pericardium from moving, resulting in intact, but stretched, tag lines.

Cine MR may also show the characteristic septal bounce: As the tricuspid valve opens, the interventricular septum bounces to the left.

Thickening of the pericardium (> 4 mm) is also suggestive.

The physiologic consequence of these adhesions is incomplete diastolic filling of the heart that results in dilatation of the right atrium, superior and inferior venae cavae, and hepatic and azygos veins. Hepatic venous congestion, in turn, may result in the nutmeg liver appearance. The right ventricle may be normal in size or narrowed.

A mnemonic that works for me is "CA Ca"=Constrictive Adhesions Calcification.

Restrictive cardiomyopathy and constrictive pericarditis may cause identical hemodynamic findings. Restrictive cardiomyopathy is rare and is caused by an infiltrative process that leads to myocardial stiffening (as opposed to the pericardial adhesions of constrictive pericarditis). It is most often seen in dialysis patients with chronic amyloidosis. The pericardial findings in constrictive pericarditis (see above) would obviously not be seen in restrictive cardiomyopathy.

References

Miller SW and Boxt LM. Chapter 8. in Cardiac Imaging, the Requisites Third edition, Miller SW, Boxt LM, and Abbara S, eds. Mosby 2009. pp 269-271.