Constrictive pericarditis

Constrictive pericarditis can present with symptoms such as difficulty breathing, fatigue, abdominal swelling, or swelling of legs.^[1] Physical examination findings can include elevated Jugular venous pressure (JVP), Kussmaul's sign, Peripheral edema, Ascites, Hepatomegaly.^[1] Auscultation of the heart may reveal a high-pitched sound during the heart's relaxation phase (Diastole) known as a pericardial knock.

In areas of the world where Tuberculosis is endemic, it is the most common cause of constrictive pericarditis.^[4] Outside of these areas the next most common cause is typically idiopathic or viral in nature.^[3] Causes of constrictive pericarditis can include:

• Tuberculosis^[5]
• Incomplete drainage of purulent pericarditis^[5]
• Fungal and parasitic infections^[5]
• Chronic pericarditis^[5]
• Postviral pericarditis^[5]
• Postsurgical^[5]
• Following MI, post-myocardial infarction^[5]
• Prior radiation to the Mediastinum^[3]
• In association with Pulmonary Asbestosis^[6]

The pathophysiological characteristics of constrictive pericarditis are due to a thickened, fibrotic pericardium that forms a non-compliant shell around the heart. This shell prevents the heart from expanding when blood enters it. As pressure on the heart increases, the Stroke volume decreases as a result of a reduction in the ability of the heart to fill blood during Diastole. ^[7] This results in significant changes in blood flow based on the stage of respiration.^[8]

During inspiration, pressure in the thoracic cavity decreases but is not relayed to the left atrium which can lead to a reduced flow to the left atrium and ventricle. During diastole, less blood flow in the left ventricle allows for more room for filling in right ventricle and therefore a septal shift occurs.^[9]

During expiration, the amount of blood entering the left ventricle will increase, allowing the interventricular septum to bulge towards the right ventricle, decreasing the right heart ventricular filing.^[10]

Constrictive pericarditis can be categorized into general syndromes that reflect the nature of the disease development and course.^[11]

• Transient (subacute) constrictive pericarditis: constrictive pathophysiology may be reversible due to a transient inflammatory state that resolves without significant fibrosis.^[3]
• Advanced (chronic) constrictive pericarditis: constrictive pathophysiology may be irreversible due to significant fibrosis and loss of elasticity over a longer period of time (often 3-6 months).^[3]
• Effusive-constrictive pericarditis: similar yet distinct disease process to constrictive pericarditis characterized by a constrictive pathophysiology and the presence of a pericardial effusion.^[3]

The diagnosis of constrictive pericarditis is often difficult to make. In particular, restrictive cardiomyopathy has many similar clinical features to constrictive pericarditis, and differentiating them in a particular individual is often a diagnostic dilemma.^[12]

• Chest X-Ray - pericardial calcification (common but not specific), pleural effusions are common findings.^[13]
• Echocardiography - the principal echographic finding is changes in cardiac chamber volume.^[13]
• CT and MRI - CT scan is useful in assessing the thickness of pericardium, calcification, and ventricular contour. Cardiac MRI may find pericardial thickening and pericardial-myocardial adherence. Ventricular septum shift during breathing can also be found using cardiac MRI. Late gadolinium enhancement can show enhancement of the pericardium due to fibroblast proliferation and neovascularization.^[10]
• BNP blood test - tests for the existence of the cardiac hormone brain natriuretic peptide, which is only present in restrictive cardiomyopathy but not in constrictive pericarditis^[14]
• Conventional cardiac catheterization^[15]
• Physical examination - can reveal clinical features including Kussmaul's sign and a pericardial knock.^[15]

Transient or subacute constrictive pericarditis is treated with anti-inflammatory medication and can resolve without surgical intervention in many cases.^[3] Cases that do not resolve with medication may be treated similar to chronic constrictive cases which often require surgical intervention.^[3] In these cases the outcome of surgery may be improved as the pericardial inflammation would be decreased due to the medication trial.^[3]

The definitive treatment for advanced or chronic constrictive pericarditis is a radical Pericardiectomy, which is a surgical procedure in which the entire pericardium is peeled away from the heart. This procedure has significant risk involved,^[16] with mortality rates of 6% or higher in major referral centers.^[17]

A poor outcome is often the result after a pericardiectomy is performed for radiation-induced constrictive pericarditis, and some patients may develop heart failure post-operatively.^[18]

Constrictive pericarditis is a rare complication of many pericardial diseases.^[11] It seen as a complication in approximately 1% of idiopathic pericarditis cases, and even fewer cases post cardiac surgery.^[11]

The geographic distribution of constrictive pericarditis can be categorized based on etiology, with idiopathic or viral pericarditis considered to be the leading cause in Western countries.^[11]In Western countries the remaining causes tend to be post-surgical, post-radiation, infectious, and connective tissue disorders.^[11] In some developing countries Tuberculosis has been noted as the leading cause of constrictive pericarditis.^[4]