title: Computerized evaluation of Valsalva's Maneuver before and during alpha-adrenoceptor blockade with alfuzosin.
abstract: 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.
mesh_terms: D000317:Adrenergic alpha-Antagonists; D000328:Adult; D000959:Antihypertensive Agents; D001794:Blood Pressure / Q000187:drug effects; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008954:Models, Biological; D011799:Quinazolines; D014636:Valsalva Maneuver
chemical_list: D000317:Adrenergic alpha-Antagonists; D000959:Antihypertensive Agents; D011799:Quinazolines; C047638:alfuzosin