Why is pulmonary hypertension rare in patients with constrictive pericarditis?

From the Guidelines

Pulmonary hypertension is rare in patients with constrictive pericarditis because the rigid, thickened pericardium prevents the transmission of elevated right ventricular pressures to the pulmonary circulation. In constrictive pericarditis, the heart becomes encased in a stiff, fibrotic pericardial sac that restricts cardiac filling during diastole. This restriction affects all cardiac chambers relatively equally, limiting right ventricular dilation that would typically occur in response to increased afterload. The constrictive process essentially "protects" the pulmonary vasculature from the high pressures that would otherwise develop. Additionally, the equalization of pressures across all cardiac chambers during diastole leads to prominent venous congestion in the systemic circulation rather than pulmonary congestion. The right ventricle cannot generate sufficient pressure to cause pulmonary hypertension because it is mechanically constrained by the rigid pericardium. This physiological mechanism explains why patients with constrictive pericarditis typically present with peripheral edema, ascites, and hepatic congestion rather than pulmonary symptoms that would suggest pulmonary hypertension, as supported by the guidelines on the diagnosis and management of pericardial diseases 1.

The diagnosis of constrictive pericarditis is based on a combination of clinical, echocardiographic, and hemodynamic features, including pericardial thickening, calcifications, and the presence of a "dip-plateau" sign in the pressure curve of the right and/or left ventricle 1. The management of constrictive pericarditis involves pericardiectomy, which is the accepted standard of treatment in patients with persistent and prominent symptoms, as recommended by the European Society of Cardiology 1.

In contrast, pulmonary hypertension is a condition characterized by elevated pulmonary arterial pressure, which can lead to right ventricular failure and death if left untreated, as described in the guidelines for the diagnosis and management of pulmonary hypertension 1. The diagnosis of pulmonary hypertension is based on a mean pulmonary arterial pressure >20 mmHg at rest, as measured by right heart catheterization, and the clinical classification of pulmonary hypertension includes several groups, including pulmonary arterial hypertension, pulmonary hypertension due to left heart disease, and pulmonary hypertension due to lung diseases and/or hypoxia 1.

However, in the context of constrictive pericarditis, the development of pulmonary hypertension is rare due to the mechanical constraints imposed by the rigid pericardium, which prevents the transmission of elevated right ventricular pressures to the pulmonary circulation. Therefore, the primary concern in patients with constrictive pericarditis is the management of the underlying condition, rather than the development of pulmonary hypertension, as supported by the most recent and highest quality study on the topic 1.

Key points to consider in the management of constrictive pericarditis include:

• The diagnosis of constrictive pericarditis is based on a combination of clinical, echocardiographic, and hemodynamic features.
• Pericardiectomy is the accepted standard of treatment in patients with persistent and prominent symptoms.
• The development of pulmonary hypertension is rare in patients with constrictive pericarditis due to the mechanical constraints imposed by the rigid pericardium.
• The primary concern in patients with constrictive pericarditis is the management of the underlying condition, rather than the development of pulmonary hypertension.

From the Research

Pathophysiology of Constrictive Pericarditis

• Constrictive pericarditis is a condition where the pericardium becomes fibrotic and noncompliant, leading to impaired ventricular filling and heart failure 2.
• The disease is characterized by clinical signs of right heart failure due to loss of pericardial compliance 3.
• Constrictive pericarditis can present with right-sided heart failure symptoms, including dyspnea and fatigue, due to the rigid pericardium encasing the heart and causing impaired diastolic filling 4.

Relationship between Constrictive Pericarditis and Pulmonary Hypertension

• Pulmonary hypertension is not a typical feature of constrictive pericarditis, and its presence can be used as a diagnostic criterion to rule out constrictive pericarditis in favor of restrictive cardiomyopathy 2.
• However, some studies have reported cases of constrictive pericarditis with severe pulmonary hypertension, highlighting the complexity of the disease 2, 5.
• The presence of pulmonary hypertension in constrictive pericarditis can be associated with concomitant myocardial disease and is linked to poorer outcomes, including increased mortality 5.

Clinical Significance of Pulmonary Hypertension in Constrictive Pericarditis

• Pulmonary hypertension can be classified into different types, including isolated postcapillary PH and combined postcapillary and precapillary PH, each with distinct clinical implications 5.
• The development of combined postcapillary and precapillary PH in constrictive pericarditis is associated with increased pulmonary vascular resistance and poorer long-term survival 5.
• The diagnosis of constrictive pericarditis with pulmonary hypertension requires a comprehensive approach, including echocardiography, cardiac catheterization, and magnetic resonance imaging 4, 5.