Aids to cardiac auscultation.

Despite the wide application of aids for cardiac auscultation, their diagnostic efficacy has not been comprehensively evaluated. The most commonly used auscultatory aids, including respiration (Carvallo's maneuver), Müller and Valsalva maneuvers, squatting, standing, handgrip, intrinsic cycle length changes, and amyl nitrite, are discussed. A review of the literature suggests that enthusiasm for these aids must be tempered because of limitations in sensitivity and specificity as well as weaknesses in the methods used in the validation studies.