Comparison between the Valsalva maneuver and a newly-devised expiratory valve on splitting of the second heart sound.
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D005260:Female; D006331:Heart Diseases / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010701:Phonocardiography; D012119:Respiration; D014636:Valsalva Maneuver