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Constrictive pericarditis: Pathophysiology, diagnosis, echocardiography and treatment . A cardiology case (video) and notes

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A Cardiology Video: Constrictive pericarditis: A condition difficult to diagnose !  The pathophysiology, diagnosis, echocardiography and treatment of constrictive pericarditis are being explained. A presentation of the important facts, with images and videos  for review purposes.



NOTES
The pericardium is a two-layered sac that encircles the heart, consisting of an inner serosal layer (visceral pericardium) adhering to the surface of the heart,which is reflected at the origin of the great vessels and continuous to an outer fibrous layer (parietal pericardium). Normally the two layers are separated by a small amount of fluid (about 10 - 50 ml), which reduces friction. The pericardium prevents extreme dilatation of the heart during sudden rises of intracardiac volume and acts as a barrier to limit spread of infection from the adjacent lungs. Nevertheless, its physiological significance is limited. Patients with absense of the pericardium, either congenital, or after heart surgery generally do very well, without it.

Constrictive pericarditis (CP)
is present when a thickened and fibrotic (and often calcified) pericardium restricts the filling of the heart.The consequence is elevation and equlibration of filling pressures in all cardiac chambers, as well as in the systemic and pulmonary veins. The diastolic filling pressures are almost the same in all cardiac chambers. In the early phase of diastole there is an abnormally rapid ventricular filling due to the elevated atrial pressures. Then, during early to mid diastole, ventricular filling is abruptly halted, when ventricular volume reaches the limit set by the rigid pericardium. CP is characterized by a uniform impairment of filling of all heart chambers. Impaired left ventricular filling causes a reduction of cardiac output, resulting in easy fatiguability. Moreover, the elevated systemic venous pressure and reduced cadiac output causes retention of sodium and water by the kidneys, contributing to edema and ascites. Myocardial contractile function is usually preserved (normal). CP is a rare disease (about 1 case in every 100,000 hospital admissions).


Causes : CP can occur after acute pericarditis which is usually idiopathic or viral (9 % of the cases of acute pericarditis will develop CP), also after heart surgery, therapeutic mediastinal radiation, as a complication of an autoimmune connective tissue disease (for example systemic lupus erythematosus), after an infection (i.e. after purulent pericarditis or tuberculosis, which was a common cause in the past, but it is now rare). The above causes are mentioned according to their frequency (the commonest first). Miscellaneous, less common, causes include malignancy, trauma, uremic pericarditis, drug-induced, asbestosis, sarcoidosis.

Symptoms and signs : Patiens usually present with symptoms of heart failure (HF) : dyspnea (due to pumonary venous congestion) easy fatiguability, edema, ascites, hepatomegaly (hepatic enlargement), jugular venous distention. Edema, ascites, hepatomegaly and jugular venous distention are due to systemic venous congestion (elevated systemic venous pressure).Usually the manifestations of right heart failure (due to systemic venous congestion) precede the manifestations of left heart failure due to pulmonary venous congestion (exertional dyspnea, nocturnal dyspnea, orthopnea, cough) that appear later in the course of the disease. Less commonly patients present with chest pain, atrial arrhythmia (impaired ventricular filling causes result in raised atrial pressures and atrial dilatation, which predisposes to atrial arrhythmias such as atrial fibrillation) or abdominal symptoms (due to hepatomegaly, or ascites). Sometimes cardiac cirrhosis can ensue with prominent ascites and jaundice.

The ECG in constrictive pericarditis (CP) often shows nonspecific findings such as T-wave flattening or inversions.
Chest radiography may show a calcified pericardium (rare).
The echocardiogram in CP shows an abnormal diastolic 
motion of the ventricular septum. There is also marked respiratory variation in ventricular size and in ventricular filling (>25% respiratory variation of the peak early diastolic velocity of the transmitral flow E). These three findings described above are due to ventricular interdependence. Inferior vena cava is dilated (it is seen in the subcostal view) due to the elevated central venous pressure. 
At times, a thickened pericardium (>4 mm) can be seen  from the subcostal view, but usually transthoracic echocardiography does not allow an assessment of pericardial thickness.
Useful for  identifying thickened (>4 mm) and / or calcified pericardium is computerized tomography (CT) or magnetic resonance imaging (MRI).

Right-heart catheterization is important for diagnosing constrictive pericarditis, because there are some characteristic hemodynamic findings, such as : 
The pressure curves of the right and left ventricles in diastole show a characteristic dip and plateau pattern, (it looks like the symbol of square root : "rhe square root sign"). At early diastolic filling there is a rapid rise in diastolic pressure which abruptly reaches a plateau because the ventricles quickly reach the limit set by the rigid pericardium. Thus, they cannot dilate in order to allow further filling with blood.
Diastolic pressures of the cardiac chambers: Elevation and equalization of right atrial diastolic pressure, right ventricular diastolic pressure, pulmonary capillary wedge pressure (which is used as a measure of left atrial pressure, since it is an approximation of the left atrial pressure), and left ventricular diastolic pressure is observed in constrictive pericarditis.
 The right atrial pressure tracing shows prominent X and Y descents (resulting  in a W configuration).

TREATMENT
Diuretics can be useful for congestive manifestations, but caution is advised to avoid hypotension.
Avoid calcium channel blockers and beta-blockers because in constrictive pericarditis sinus tachycardia  is a compensatory mechanism for impaired cardiac filling. Thus these drugs, by reducing the heart rate, can also reduce cardiac output in this condition.
The definitive treatment for CP is total pericardiectomy (surgical
removal of the pericardium). Pericardiectomy has a high surgical mortality (about  
5% -15%), but it is also a very effective treatment, leading to symptomatic improvement in the majority of patients (90% of the patiens).
Occasionally, in some of the patients who develop constrictive pericarditis after radiation therapy, restrictive cardiomyopathy may also be present. In such cases surgical pericardiectomy is less effective.


NOTE 
For the ESC guidelines on diagnosis and treatment of pericardial disease (including acute pericarditis, pericardial effusion, 
constrictive pericarditis, etc), please use this link:

2015 ESC Guidelines for the diagnosis and management of pericardial diseases