Methods: Of 2,300 patients who underwent open heart surgery between January 2010 and September 2012, 118 (39 males, 79 females; mean age: 55.4±15.2 years; range 19 to 80 years) who required a revision surgery for bleeding and/or cardiac tamponade were retrospectively analyzed. Data of TTE were available in 73 patients. Diagnostic specificity and sensitivity of the TTE and clinical parameters including hypotension, oliguria, and metabolic acidosis were estimated with respect to surgical confirmation. Sensitivity and specifity rates were compared using the Cochrane Q test and McNemar test.

Results: The mean and median time from the first operation were 12.0±11.7 and nine days, respectively (0 to 62 days). Overall mortality occurred in 28 patients (38.4%). Among patients with surgically confirmed tamponade, TTE showed 64.5% sensitivity, whereas hypotension was present in 92.0%, oliguria in 80.6% and metabolic acidosis in 45.1% (p<0.001). Among patients with unconfirmed tamponade, TTE showed 90.9% specificity, whereas hypotension was present in 54.5% patients, oliguria in 81.8% and metabolic acidosis in 45.4% (p=0.07). Specificity rates showed constancy with time, while sensitivity rates tended to increase after seven days.

Conclusion: Transthoracic echocardiography plays an important role in the evaluation of postoperative hemodynamic impairment. However, its high false negativity rate for diagnosis of cardiac tamponade should be kept in mind to prevent further delay in patients with high clinical suspicion.