(A) The pericardium surrounding the heart in a normal physiologic setting and in tamponade. The pericardium can be seen to extend to the proximal great vessels. Note the large amount of effusion in the image on the right, which is consistent with chronic pericardial stretch and leading more slowly to tamponade than would normally be the case in iatrogenic perforations. Courtesy Mayo Foundation for Medical Education. (B) Pressure volume curve of normal pericardium (left) and compliant pericardium (right). In the setting of rapid onset of effusion in the normal pericardium, low volumes, typically rising from a range beginning lower than 50 cc and rising to some unspecified point, lead to a rise in pressure that exceeds the limit of pericardial stretch, with early onset of tamponade physiology. More compliant pericardium, a result of chronic stretching, does not result in critical extramural pressures until substantially higher volumes, in some cases more than a liter. Reprinted, with permission, Turi (66). RA = right atrial.

Echocardiographic image showing pericardial tamponade with right-sided collapse. Reprinted, with permission, from Priscilla Peters, Cooper University Hospital, Camden, New Jersey. Eff = effusion; LA = left atrium; LV = left ventricle; RA = right atrium; RV = right ventricle.

(Left) Very early signs of pericardial tamponade. Although the aortic pressure has not fallen, there is a mild elevation of right atrial (RA) pressure and loss of the rapid y descent (arrow). This indicates that pericardial effusion has already started to cause problems filling the ventricle. The increased sympathetic discharge and vasoconstriction allows the aortic pressure (Ao) to remain elevated. (Right) As the amount of pericardial effusion progresses, there will be a decrease in pulse pressure and a relative tachycardia. However, pulsus paradoxus is not yet present.

The RA pressure is severely elevated. Most of the increase in pressure occurs at the onset of atrial contraction and there is both loss of x and y descent. The Ao and pulse pressure have significantly fallen. During inspiration (Insp), there is a further drop in pulse pressure than during expiration (Exp). This demonstrates classic pulsus paradoxus. Abbreviations as in Figure 3.

Pulse pressure is obliterated during inspiration (red arrows). Reprinted, with permission, from Turi (66).

There is a localized pericardial effusion (PE), which is all posterior. There is compression of the left ventricle. The right ventricle has invagination during diastole. The posterior location of the PE would necessitate an entry for pericardiocentesis from a modified apical window. Abbreviations as in Figure 2.

Transmitral Doppler velocity curves (showing the E and A waves) with simultaneous left ventricular and pulmonary artery wedge pressures (PAWP) in patient with pericardial tamponade. During inspiration there is a marked decrease in the initial E velocity. This is due to a dissociation of intracardiac and intrathoracic pressures seen in pericardial disease. Abbreviations as in Figure 2.

The growth of transseptal puncture over a decade of electrophysiology procedures in 33 hospitals in Italy. Reprinted, with permission, from De Ponti et al. (10).

(A) High-fidelity left and right ventricular pressure traces in a patient with pericardial tamponade. There is marked elevation and equalization of diastolic pressures with loss of early diastolic filling. The left ventricular end-diastolic pressure is 32 mm Hg. During the fourth beat, there is a marked drop in left ventricular systolic pressure and a rise in right ventricular systolic pressure, indicating enhancement of ventricular interaction. Overall, the systolic pressure is <100 mm Hg. (B) The same patient after receiving emergency treatment with intravenous fluids and nitroprusside (NTP). Although there is still evidence of enhancement of ventricular interaction and a pulsus paradoxus, the systolic pressure of the left ventricle has significantly increased to 120 mm Hg. These medical treatments are a "temporizing" approach to stabilize hemodynamics before emergency pericardiocentesis is performed.