Respiratory variation in mitral flow velocity in pericardial effusion and cardiac tamponade.

It has been suggested that the presence of increased respiratory variation in mitral flow velocity (RVIMFV) in patients with pericardial effusion (PE) represents significant hemodynamic compromise regardless of the amount of PE or 2D-echo findings. Recent experimental data do not, however, support this aspect. The aim of this study was to evaluate the relation of RVIMFV to clinical, hemodynamic, and 2D-echo findings in patients with PE and cardiac tamponade (CT). Therefore, 11 patients with PE and CT were studied with right-heart, pericardial, and arterial pressure measurements in conjunction with 2D and Doppler echocardiography during three stages of gradually decreasing PE, ie, (1) before any PE drainage, (2) after partial PE drainage, and (3) after full drainage. A significant RVIMFV was noted during all three stages of our study. It was maximal at the early stage [respiratory difference in mitral flow velocity (delta MFV): 16.8 +/- 6.3 cm/sec, 24.1%, P = 0.0000026] coinciding with pulsus paradoxus, high pericardial pressure, and diastolic right heart collapse, and it decreased slightly after partial drainage when all signs of CT receded (delta MFV: 13.7 +/- 9.7 cm/sec, 18%, P = 0.00043). However, there was still some RVIMFV (delta MFV: 8.7 +/- 7.6 cm/sec, 13.9%, P = 0.0017) after full pericardial drainage. It is concluded that the presence and the magnitude of RVIMFV is not predictive of hemodynamic compromise in patients with PE.