Hemodynamic derangements of cardiac tamponade are generally believed to result from compression of the cardiac chambers, which limits diastolic filling. The character and magnitude of the alternation are determined by the compliance characteristics of the pericardium and the total pericardial fluid volume. During serial pericardial fluid withdrawal, improvement of hemodynamic alternations is expected in patients with pericardial effusion. Method : Hemodynamic study was performed before and during serial fluid drainage in 11 patients with chronic moderate to severe pericardial effusion.

1) Intrapericardial pressure was elevated and equal to mean right atrial ventricular diastolic, and pulmonary capillary wedge pressure. Pulmonary arterial and right ventricular systolic pressure were also midly elevated equal to one another. 2) Pericardial fluid was gradually removed in 50ml aliquots in all patients. The most significant hemodynamic improvement occured during intial 50mL withdrawal. Futher drainage of intrapericardial fluid was accompanied by slight hemodynamic improvement. 3) There were significant correlations between total pericardial fluid volume and intrapericardial and right atrial pressure (r=0.75 (p<0.005), r=0.71(p<0.01)). Correlations between intrapericardial pressure and right atrial, right ventricular diastolic and pulmonary capillary wedge pressure were also significant. 4) Two groups of patient could be distinguished based upon intrapericardial pressure as 7mmHg. More significant hemodynamic changes were in 6 patients with higher intrapericardial pressure after withdrawal of 200mL fluid.

In chronic moderate to severe pericardial effusion, the most significant hemodynamic improvement occurred during initial fluid drainage. Early pericardiocentesis is important in management of pericardial effusion with high intrapericardial pressure.