After two hours post coronary artery bypass surgery the client experienced a central venous pressure increasing from 13 mm Hg to 17 mm Hg within a half hour. The systolic blood pressure dropped to 90 mm Hg on inspiration and rose to 110 mm Hg on expiration. Heart sounds are distant upon auscultation, and decreased electrocardiogram (ECG) waveform amplitudes are assessed. Which is the cause of these clinical manifestations?

Rationale: A. Primary cardiomyopathy: Cardiomyopathy involves chronic structural and functional heart muscle changes, often leading to heart failure symptoms like dyspnea and fatigue. It does not present acutely with pulsus paradoxus or a rapid rise in central venous pressure. B. Acute pericarditis: Pericarditis causes chest pain and pericardial friction rub but rarely results in hemodynamic collapse. While inflammation may lead to fluid accumulation, cardiac tamponade is the condition that produces the severe pressure and pulsus paradoxus described. C. Infective endocarditis: Endocarditis involves infection of heart valves and presents with fever, murmurs, and embolic phenomena. It does not cause acute pressure changes, distant heart sounds, or pulsus paradoxus immediately after cardiac surgery. D. Cardiac tamponade: The rapid rise in central venous pressure, hypotension with pulsus paradoxus, distant heart sounds, and low ECG voltage are classic signs of cardiac tamponade. Postoperative fluid accumulation in the pericardial sac compresses the heart, impairing ventricular filling and causing circulatory collapse if not promptly relieved.