Can cardiac tamponade be diagnosed by echocardiography? Experimental studies

N-terminal pro-B-type natriuretic peptide as a marker of disease severity in patients with pericardial effusions

BACKGROUND/AIMS

N-terminal pro-B-type natriuretic peptide (NT-proBNP) has recently been introduced as a useful marker in diagnosing underlying disease in patients with dyspnea and for determining the prognosis of patients with heart failure. The purpose of this study was to evaluate the value of the NT-proBNP as a marker of disease severity in patients with pericardial effusions.

METHODS

We enrolled 69 consecutive patients who showed moderate or large pericardial effusion with preserved left ventricular (LV) systolic function; 42 patients finally participated in the study, and 13 (31.0%) of them showed cardiac tamponade. We analyzed the etiologies, the clinical and echocardiographic variables, and the serum NT-proBNP levels in these patients.

RESULTS

The mean NT-proBNP level was 751+/- 1002 ng/L (range 5 to 5289), and the median level was 385 ng/L (interquartile range 152 to 844). The NT-proBNP levels were higher in those patients with jugular venous distension (p=0.002), pulsus paradoxus (p=0.016), heart rate > or = 100/min (p=0.006), cardiac tamponade (p=0.001), large pericardial effusion (p=0.029), exaggerated respiratory variation of the transmitral inflow (p=0.006), or plethora of the inferior vena cava (p=0.01). The NT-proBNP levels showed significant correlation with heart rate (r=0.517, p<0.001) and the diameter of the inferior vena cava (r=0.329, p=0.03).

CONCLUSIONS

NT-proBNP may be useful as a marker of disease severity in patients suffering from pericardial effusion, but further prospective studies with more patients will be needed.

The pathophysiology of pericardial disease--contributions derived from echocardiography/Doppler studies in animal models

The use of acute and chronically prepared animal models of pericardial disease free of the confounding influences of other disease processes have greatly accelerated the development of echocardiographic and Doppler diagnostic methods and have allowed the correlation of these noninvasive findings with hemodynamic abnormalities.

Combined posteroanterior subepicardial fat simulating the echocardiographic diagnosis of pericardial effusion

The location and relative size of echo-free spaces observed by cardiac ultrasound have been considered reliable signs for distinguishing pericardial fat from fluid; spaces that are exclusively anterior have been considered to represent fat, while spaces that are exclusively or predominantly posterior have been considered to represent fluid. In the present study, the location and relative size of echo-free spaces in eight patients suggested the diagnosis of pericardial effusion; evaluation by computed tomography or thoracotomy, or both, in six and necropsy in two, however, disclosed that these echo-free spaces--posterior as well as anterior--were exclusively due to fat. Age appeared to be as important a predisposing factor as obesity in the accumulation of excess subepicardial fat. No M-mode or two-dimensional features were found to be reliable in differentiating fat from fluid, although excessive amplitude of the posterior pericardial echo on the M-mode study favored the diagnosis of fat. Thus, the finding of echo-free spaces by cardiac ultrasound, even when the posterior space is isolated or larger than an accompanying anterior space, is not necessarily indicative of pericardial fluid. In elderly patients, in particular, posterior echo-free spaces due to fat may invite an incorrect diagnosis of pericardial effusion or pericarditis. In patients in whom echo-free spaces represent an unexpected finding of cardiac ultrasound examination, computed tomography of the chest may be helpful in establishing whether they are due to fat or fluid.

Clinical and hemodynamic correlation in patients with pericardial effusion and swinging heart by echocardiography

The clinical and hemodynamic findings in 13 consecutive patients with "swinging heart" on M-mode echocardiography were analyzed. In these patients the anterior right ventricular and posterior left ventricular walls and interventricular septum moved almost parallel to each other throughout the cardiac cycle, often with exaggerated excursion. In 10 of 13 patients right heart catheterization revealed the hemodynamic profile of cardiac tamponade, while one additional patient was found to have evidence of cardiac compression at the time of surgery. In the remaining two patients no acute invasive diagnostic procedures were performed. During the same observation period cardiac tamponade was observed in five patients without echocardiographic evidence of a swinging heart, and four of these had large clots in the pericardial space. Thus, the swinging heart pattern appears to be a reliable marker of cardiac tamponade, except in those patients with intrapericardial lesions which mechanically limit cardiac motion.

Failure of the aortic valve to open during inspiration in cardiac tamponade

A new echocardiographic sign, failure of the aortic valve to open during inspiration, is described in a 35-year-old man with cardiac tamponade. There was disappearance of the radial pulse and blood pressure during inspiration and the usual clinical and echocardiographic signs.

Diagnosis and management of postoperative pericardial effusions and late cardiac tamponade following open-heart surgery

The clinical and laboratory findings of 28 patients identified as having late pericardial effusions were examined. Eleven of these patients were asymptomatic; 9 patients had moderate symptoms including fatigue, malaise, weight gain, and dyspnea on exertion, and 8 patients with similar symptoms had evidence of cardiac tamponade. Ten patients underwent right heart catheterization in the intensive care unit; normal hemodynamics were confirmed in 4 and cardiac tamponade in 6 patients. Pericardiocentesis was effective in decompressing cardiac tamponade in 7 of 8 patients. One patient required operative subxiphoid drainage after unsuccessful pericardiocentesis. In addition, 5 patients with moderate clinical symptoms and pericardial effusions, who did not have cardiac tamponade, underwent pericardiocentesis because of a need for chronic anticoagulant therapy. The remaining patients were managed successfully by observation, discontinuation of warfarin when possible, fluid restriction, and diuretic therapy. All but 1 patient was symptomatically improved. A diagnostic and therapeutic schema is presented as an aid to early recognition of this troublesome and potentially lethal complication.