Y Descent in Cardiac Tamponade and Constrictive Pericarditis

Hemodynamic Features

• In cardiac tamponade, the right atrial pressure waveform shows a preserved systolic X descent but an absent or diminished diastolic Y descent, due to diastolic equalization of pressures in the right atrium and right ventricle, resulting in lack of effective flow across the tricuspid valve in early ventricular diastole 1, 3, 4
• In constrictive pericarditis, the Y descent is prominent and preserved, representing rapid early diastolic filling that abruptly stops when the ventricle reaches its limited volume due to the non-compliant pericardium 2, 5

Diagnostic Implications

• The presence or absence of the Y descent is a key differentiating feature between cardiac tamponade and constrictive pericarditis, with tamponade showing a diminished or absent Y descent due to external compression preventing early diastolic filling, and constriction showing a preserved or accentuated Y descent due to rapid early diastolic filling that is abruptly halted 2, 4
• In effusive-constrictive pericarditis, the hemodynamic pattern may initially resemble tamponade, but after pericardiocentesis, the constrictive component becomes evident with the appearance of constrictive features including the prominent Y descent 6, 7

Clinical Applications

• Cardiac catheterization remains valuable for confirming the diagnosis and quantifying hemodynamic compromise in both conditions, and the pattern of the Y descent should be evaluated in context with other hemodynamic parameters 2, 3, 6
• Monitoring of right atrial pressure during pericardiocentesis can reveal a persistent constrictive pattern in effusive-constrictive disease, and end-diastolic pressure equalization occurs between cardiac chambers due to the fixed and limited space within the thickened and stiff pericardium 1, 6