Complications of Pericarditis

Cardiac tamponade as a life-threatening condition

Cardiac tamponade is a critical complication characterized by the compression of the heart chambers. It can develop rapidly or progress gradually. The main cause of the pathology is the pathological accumulation of various substrates in the pericardial cavity: fluid, blood, pus, thrombotic masses, or gas. Etiologically, this condition is caused by severe inflammation, mechanical trauma, myocardial rupture, or aortic dissection.

Clinically, progressive tamponade manifests with specific physical examination markers. The most important of these is pulsus paradoxus (a decrease in systolic blood pressure during inspiration). Palpation reveals the disappearance of the apex beat, and auscultation shows a uniform weakening and muffling of the first and second heart sounds.

The physician should be particularly alert to the sudden disappearance of the pathognomonic pericardial friction rub. Dynamically, this often indicates not recovery, but the transition from dry (fibrinous) to exudative inflammation. The accumulating exudate separates the visceral and parietal layers, muffling the sound and creating a threat of cardiac compression.

Constrictive pericarditis

Constrictive pericarditis is a delayed structural consequence of previous inflammation. Its pathogenesis is based on marked fibrinous thickening and subsequent calcification of predominantly the parietal (much less frequently, the visceral) layer of the pericardium.

These morphological changes turn the elastic pericardial sac into a rigid, immobile "shell". From a hemodynamic perspective, this creates a mechanical obstacle to the normal diastolic filling of the heart chambers with blood.

The constrictive form is frequently the outcome of tuberculous pericarditis. In this etiology, caused by Mycobacterium tuberculosis (although the bacterium cannot always be detected), the pathology is characterized not only by thickening but also by the formation of dense pathological adhesions between the pericardial layers.

Evaluation of effusion and indications for pericardiocentesis

For the timely detection of complications, instrumental evaluation of the amount of effusion is necessary. The method of first choice, strictly indicated when fluid is suspected, is transthoracic echocardiography (TTE).

The volume of inflammatory exudate correlates with the degree of diastolic separation of the layers:

• Minimal effusion — visualized exclusively in systole.
• Less than 1 cm — approximately 300 ml of fluid.
• From 1 to 2 cm — approximately 500 ml.
• More than 2 cm — over 700 ml (large amount).

An alternative precise method is magnetic resonance imaging (MRI). In MRI morphometry, a pericardial thickness value of more than 4 mm is considered pathological fluid accumulation, and combining weighted sequences allows the nature of the effusion to be determined.

Surgical intervention — pericardiocentesis (puncture) — is indicated upon the detection of a large amount of effusion (echo-free space ≥ 2 cm), in the presence of a clinical threat of tamponade, and when purulent inflammation is strongly suspected.

Combined myocardial involvement and secondary forms

A complication of pericardial inflammation can be the involvement of the adjacent heart muscle. Myopericarditis (pericarditis with suspected myocardial involvement) and perimyocarditis (myocarditis primarily dominates, with secondary pericardial involvement) are distinguished. Concomitant myocardial involvement is indicated by the appearance of a gallop rhythm (third/fourth heart sounds) and a systolic murmur of relative mitral regurgitation.

Pericarditis can occur as a complication of acute myocardial infarction (epistenocarditic). The probability of its development depends on the volume of necrosis, though it has no independent prognostic significance.

When acute rheumatic fever (ARF) is suspected, the appearance of a friction rub indicates pancarditis. There is an important rule: if isolated pericarditis is diagnosed without signs of valvulitis, the diagnosis of ARF is called into question and requires in-depth investigation.

Class and exam questions

What else to study on this topic

• Magnetic resonance imaging (MRI) in cardiology: assessment of inflow patterns, edema, infarction, and myocardial fibrosis.
• Tuberculous pericarditis: features of pathogenesis, difficulty in isolating the pathogen, and high association with HIV infection.
• Classification of pericarditis by course: acute, recurrent, subacute, and chronic (with timeframes specified).
• Specific causes of dry pericarditis: viral, uremic, post-myocardial infarction Dressler syndrome, and systemic diseases.
• Differential diagnosis of isolated pericarditis and acute rheumatic fever.

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