Paradoxical Pulse Is Common In Pericardial Effusion

Pericardial effusion often presents with a unique pulse known as a paradoxical pulse. This phenomenon occurs when the pulse becomes difficult to detect or significantly weakens during inhalation, sometimes referred to as pulsus paradoxus. The underlying causes are explained below.

Understanding The Mechanism Of Paradoxical Pulse

During normal inhalation, the intrathoracic pressure becomes negative, which typically enhances venous return to the heart. However, in the presence of pericardial effusion, the fluid surrounding the heart restricts the right ventricle's ability to expand. As a result, the volume of blood entering the right ventricle is reduced. This leads to a decrease in the amount of blood pumped into the pulmonary artery and subsequently less blood returning to the left side of the heart. The reduced left ventricular output manifests as a weakened or absent pulse during inspiration.

Impact Of Pulmonary Circulation On Pulse Changes

In addition to the mechanical constraint on the right ventricle, the pulmonary circulation is also affected. During inhalation, the pulmonary vasculature expands, allowing more blood to be retained in the lungs rather than flowing into the left atrium. This further diminishes the amount of blood available to enter the left ventricle, compounding the reduction in cardiac output. Consequently, the decrease in left ventricular ejection during inhalation results in a pulse that is either barely perceptible or completely absent.