Sensitivity of Right Atrial Collapse and Right Ventricular Diastolic Collapse in the Diagnosis of Graded Cardiac Tamponade

Right atrial collapse (RAC) and right ventricular diastolic collapse (RVDC) have been shown to be useful two-dimensional échocardiographie signs in well-established cardiac tamponade. To assess the value of these signs in cardiac tamponade of varying severity, we studied 8 closed-chest spontaneously breathing dogs with twodimensional echocardiography during varying grades of tamponade induced by intrapericardial saline infusion via a preplaced catheter. Early tamponade was defined as the state when pericardial effusion caused a 20% decline in cardiac output but with normal systolic arterial pressure and a pulsus paradoxus less than 10 mm Hg. Moderate and severe tamponade were stages with progressively decreasing cardiac output and systolic arterial pressure and increasing pulsus paradoxus over 10 mm Hg. Neither RAC nor RVDC was present in any animal in the control state. Sensitivity of RAC was 50% during early tamponade and 100% during moderate and severe tamponade; the specificity was 100% during all grades of tamponade. The sensitivity of RVDC was 38, 63 and 75% during early, moderate and severe tamponade; the specificity was 88% during all stages. Thus, presence of RAC and RVDC in pericardial effusion indicates that hemodynamic deterioration has begun even though conventional signs such as pulsus paradoxus may be absent. As tamponade progresses, the sensitivity of both signs increases. At all grades of tamponade, RAC tends to be more sensitive than RVDC.