Cardiac Tamponade Haemodynamics — FRCA Primary MCQ

Correct answer: E — Cardiac tamponade

Explanation lettering: D = shown as B · B = shown as D

E is correct. Raised intrapericardial pressure limits diastolic expansion of all chambers, producing elevation and near-equalisation of right atrial pressure, right ventricular end-diastolic pressure and pulmonary artery occlusion pressure. Restricted filling lowers stroke volume and cardiac output. The prominent x descent reflects preserved atrial relaxation and downward systolic movement of the tricuspid annulus, whereas the y descent is attenuated because early ventricular filling is constrained. The 14 mmHg inspiratory fall is pulsus paradoxus, caused by exaggerated ventricular interdependence. Hypovolaemia and vasodilatory shock usually have low filling pressures. Isolated left ventricular failure raises pulmonary artery occlusion pressure without equal right-sided pressure elevation. Massive pulmonary embolism can raise right atrial and right ventricular pressures, but pulmonary artery occlusion pressure is generally lower rather than equalised with them.

Reference: Chuttani K et al. Ventricular performance related to transmural filling pressure in clinical cardiac tamponade. Circulation. 1987. https://pubmed.ncbi.nlm.nih.gov/3568311/