Computerized evaluation of Valsalva's Maneuver before and during alpha-adrenoceptor blockade with alfuzosin

Methodological differences exist in the evaluation of Valsalva's Maneuver. Linear and nonlinear mathematical models were described for beat-to-beat changes in blood pressure and R-R intervals occurring during the strain and release phases of Valsalva's Maneuver. This study indicated that the strain phase is linear, whereas the release phase is nonlinear; the release phase consists of a "lag phase," a "breakpoint," and an "overshoot phase." The alpha-adrenoceptor antagonist, alfuzosin, reduced baroreflex-mediated tachycardia during the strain phase and prolonged the "time lag" and "pressure lag" during the release phase; the latter change was due entirely to the reduced systolic pressure that occurred with alfuzosin at the end of the strain phase.