Constrictive pericarditis overview

# Overview
Pericardial constriction occurs when a fibrotic, adherent pericardium restricts diastolic filling of the heart. Variants of constrictive pericarditis have been described such as transient, subtle, effusive and chronic, depending on the course of the disease. The disease process typically begins with pericardial inflammation that progresses onto fibrosis. (Pathophysiology)It may occasionally follow an episode of acute pericarditis. There is fibrous scarring of the pericardium and usually fusion of the visceral and parietal pericardium. The pericardium is composed of a double-layered sac that surrounds the heart and the roots of the great vessels. The serous layer (smooth visceral) and a fibrous layer (tough parietal) of the pericardium encloses the pericardial cavity which contains pericardial fluid.The pericardium function is to protect the heart against infection and to provide it with lubrication. Constrictive pericarditis is a chronic inflammation that leads to the thickening, fibrosis, and scarring of the pericardial sac. The thickened fibrotic pericardium restricts the normal late diastolic filling in constrictive pericarditis and results in significant respiratory variation in blood flow in the ventricles. This is known as ventricular interdependence, where the amount of blood flow into one ventricle is dependent on the amount of blood flow into the other ventricle.The intrapericardial space contains 50 mL of plasma ultrafiltrate that minimize friction during cardiac motion. pericarditis causes that can trigger the development of constrictive pericarditis are tuberculosis, viral infection, radiation therapy, trauma, post-cardiac surgery. Constrictive pericarditis is most commonly caused by conditions or events that cause inflammation to develop around the heart, including idiopathic, infectious (viral, bacterial, tuberculous, fungal, parasitic ) and purulent pericarditis. It can also occur post MI (Dressler syndrome), post surgical (CABG), post radiation therapy. Constrictive pericarditis can also be caused by or associated with connective tissue disease, pulmonary asbestosis, chronic renal failure, neoplasm (mesothelioma). Constrictive pericarditis must be differentiated from restrictive cardiomyopathy. The evaluation of ventricular interdependence between the two ventricles is the best objective method to distinguish the two syndromes. Constrictive pericarditis should also be differentiated from cardiac tamponade, right-sided atrial tumors, such as myxomas, superior vena cava syndrome, right-sided valvular abnormalities (tricuspid stenosis or tricuspid regurgitation), systolic or diastolic congestive heart failure( pressure-overload and myocardial, valvular, or atherosclerotic disease causes)

# Historical Perspective
- In 1989, Hatle et al reported the two characteristic features in constrictive pericarditis:
First, they showed dissociation between intrathoracic and intracardiac pressures
Second, enhanced ventricular interaction can also occur
- First, they showed dissociation between intrathoracic and intracardiac pressures
- Second, enhanced ventricular interaction can also occur

# Pathophysiology
The pericardium is composed of a double-layered sac that surrounds the heart and the roots of the great vessels. The serous layer (smooth visceral) and a fibrous layer (tough parietal) of the pericardium encloses the pericardial cavity which contains pericardial fluid.The pericardium function is to protect the heart against infection and to provide it with lubrication. Constrictive pericarditis is a chronic inflammation that leads to the thickening, fibrosis, and scarring of the pericardial sac. The thickened fibrotic pericardium restricts the normal late diastolic filling in constrictive pericarditis and results in significant respiratory variation in blood flow in the ventricles. This is known as ventricular interdependence, where the amount of blood flow into one ventricle is dependent on the amount of blood flow into the other ventricle.The intrapericardial space contains 50 mL of plasma ultrafiltrate that minimize friction during cardiac motion. pericarditis causes that can trigger the development of constrictive pericarditis are tuberculosis, viral infection, radiation therapy, trauma, post-cardiac surgery.

# Causes
Constrictive pericarditis is most commonly caused by conditions or events that cause inflammation to develop around the heart, including idiopathic, infectious (viral, bacterial, tuberculous, fungal, parasitic ) and purulent pericarditis. It can also occur post MI (Dressler syndrome), post surgical (CABG), post radiation therapy. Constrictive pericarditis can also be caused by or associated with connective tissue disease, pulmonary asbestosis, chronic renal failure, neoplasm (mesothelioma).

# Differentiating Pericardial constriction from other Diseases
Constrictive pericarditis must be differentiated from restrictive cardiomyopathy as they are treated very differently.  Multi-modality imaging including echocardiography with flow and tissue doppler imaging, cardiac MRI and heart catheterization are used to differentiate between the two conditions that may present with similar clinical signs and symptoms. The finding of ventricular interdependence (respiratory variation of mitral and tricuspid flows) as demonstrated by different imaging modalities is key in differentiating the two syndromes.

# Epidemiology and Demographics
Constriction can occur after almost any pericardial process. Historically, the most common etiology was tuberculosis, but in the modern age, this cause now accounts for <2% of cases. In a study of 95 patients undergoing pericardiectomy at Stanford, no cause could be found in 42% of patients. 31% occurred after radiotherapy, particularly following high dose mantle radiation for Hodgkins disease. Pericardial constriction occurred a mean of 85 months after radiotherapy, but occurred as early as 1 month and as late as 244 months. It also occurred post-operatively in 11% of cases. Connective tissue disorders accounted for 4%, neoplasm 3%, uremia 2% and sarcoidosis for 1% of cases. The likelihood of a constrictive pericarditis diagnosis is less than 10 in 100,000 hospital admissions considering only 9% of acute pericarditis patients develop pericardial constriction. This disease is more prevalent in males with a male-to-female ratio of 3:1. Constrictive pericarditis has been documented in people 8-70 years of age, with a median of 61 years of age.

# Risk Factors
Constrictive pericarditis (CP) is rare and is usually developed as a complication of acute pericarditis. Although there are no established risk factors for constrictive pericarditis, prospective studies have shown an increased risk after long-term follow-up of acute pericarditis.

# Natural History, Complications, and Prognosis
Constrictive pericarditis is when there is scarring of the sac (the pericardium) around the heart, which may require surgical stripping of the scar. Failure to diagnose or treat constrictive pericarditis could result with severe complications that include cardiac tamponade, damage to the coronary arteries, heart failure, pulmonary edema, scarring of the heart muscle.

# Diagnosis

## Diagnostic Study of Choice
The diagnosis of constrictive pericarditis is based on the clinical findings (symptoms and signs) of right heart failure, and diastolic filling impairment due to pericardial constriction. The diagnostic imaging methods include echocardiography, CT, CMR, cardiac catheterization.

## History and Symptoms
The clinical history of pericardial constriction cannot be solely used to make a diagnosis due to the multiple symptoms this disease presents. The symptoms may not be recognizable to the patients considering they develop slowly and over time. The early symptoms of pericardial constriction are often more consistent with liver disease and the patient may be erroneously referred for imaging studies of the liver.

## Physical Examination
Physical findings of patients with constrictive pericarditis may include general, cardiovascular and other organ systemic findings. General findings could be indistinct or could include muscle wasting, cachexia, or jaundice. Cardiovascular Findings include sinus tachycardia, distant or muffled heart sounds, pericardial knock, cardiac murmur, pulsus paradoxicum (paradoxus), kussmaul sign (elevation of systemic venous pressures with inspiration). Other systemic findings include hepatomegaly, spider angiomata, palmar erythema, peripheral edema.

## Laboratory Findings
Constrictive pericarditis lab findings can show evidence of congestive heart failure, or associated protein losing enteropathy, nephrotic syndrome, and LFT abnormalities consistent with hepatic congestion and chylous ascites

## Electrocardiogram
Electrocardiographic signs of constrictive chronic pericarditis are usually inconsistent and non specific. It includes left atrial enlargement, frequent atrial arrhythmias, right axis deflection, possible reduction in voltages, diffuse negative T-waves. Typical findings are normal QRS axis, low voltage, and generalized T wave flattening or inversion. Evidence of right ventricular hypertrophy or right axis deviation can present which is usually an unexplained finding (cardiac rotation and distortion), or due to the presence of severe fibrotic annular subpulmonic constriction

## X-ray
Plain chest radiographs in patients with constrictive pericarditis may show pericardial calcification, small cardiac silhouette (uncomplicated CP), large cardiac silhouette (if CP coexist with cardiomyopathy). Less reliable plain radiographic findings include an abnormal cardiac contour, such as straightening of the right atrial border and, more rarely, straightening of the right and left cardiac borders, with obliteration of the normal curves, on frontal images. The absence of calcification does not exclude the diagnosis of constrictive pericarditis.

## Echocardiography and Ultrasound
Constrictive pericarditis can present with typical echocardiographic findings, such as normal systolic function, a plethoric inferior vena cava, a restrictive mitral inflow pattern with respiratory variation, reversal of expiratory hepatic vein flow, a septal motion suggestive of enhanced ventricular interaction, or an elevated early diastolic mitral annular velocity (E) detected by tissue Doppler imaging

## CT scan
Per ESC guidelines, CT and/or CMR are indicated as second-level imaging techniques to assess calcifications (CT), pericardial thickness, degree and extension of pericardial involvement.

## MRI
MRI has been included in the multi-modality imaging guidelines for the diagnosis of constrictive pericarditis. It is of great value when echocardiography is non diagnostic of constrictive pericarditis and the suspicion remains high. MRI delineates two essential components of the evaluation: pericardial anatomy and functional imaging demonstrating ventricular interdependence. It also can be used to rule out restrictive cardiomyopathy. MRI is especially useful with the use of late gadolinium enhancement as it identifies pericardial inflammation when suspected in the context of a short duration of symptoms and elevated inflammatory markers.

## Other Imaging Findings
There are no other imaging findings associated with constrictive pericarditis.

## Other Diagnostic Studies
Cardiac Catheterization can be used for the diagnosis of constrictive pericarditis. Typically, there is equalization of diastolic pressures in all four chambers. These filling pressures are typically elevated. RVSP is usually moderately elevated but rarely exceeds 60 mmHg.

# Treatment

## Medical Therapy
Pericardial constriction is a progressive disease without spontaneous reversal of the pericardial thickening. Some patients can be medically managed for several years. Edema can be controlled with diuretics and slowing of the heart rate can maximize the diastolic filling time. Most patients eventually develop significant debility from impaired cardiac output and elevated right and left sided filling pressures.

## Surgery
Pericardiectomy is the only definitive management of chronic constrictive pericarditis. Effort should be made to remove as much of the pericardium as possible. Extensive penetration of the myocardium by fibrosis and calcification is associated with poor outcome. Operative mortality ranges from 55% to 10%.

## Primary Prevention
There are no established measures for the primary prevention of constrictive pericarditis.

## Secondary Prevention
There are no established measures for the secondary prevention of constrictive pericarditis.