Points
The Valsalva maneuver is performed by forceful expiration (about 40 mmHg) against a closed nose and mouth, producing a complex hemodynamic process involving 4 phases.
LV preload is reduced during the strain phase (phase II), and changes in mitral inflow are observed to distinguish normal from pseudonormal filling (PNF) patterns.
The patient must generate a sufficient increase in intrathoracic pressure, and the sonographer needs to maintain the correct sample volume location between the mitral leaflet tips during the maneuver. A decrease of 20 cm/s in mitral peak E velocity is usually considered an adequate effort in patients without restrictive filling.
In cardiac patients, a decrease of ≥50% in the E/A ratio is highly specific for increased LV filling pressures, but a smaller magnitude of change does not always indicate normal diastolic function.