Describe Valsalva Manocuvre in dynamic auscultation ?

This consists of deep inspiration followed by forced inhalation against a closed glottis for 10-20 seconds. It can be performed by placing examiners hand over patients abdomen and asking him to apply as much force as possible.

The normal response consists of four phases:
Phase I: Transient rise in systemic BP as straining commence.
Phase 11: Reduced venous return and systolic BP with reflex tachycardia.
Phase 111: Abrupt, transient reduction in systemic BP as straining ceases.
Phase IV: Overshoot of systemic BP and reflex bradycardia.
Phase V: A,-P, interval narrows.

S₁ and S₂ arc attenuated.
Murmurs of AS and PS and of MR and TR diminish (as stroke volume and systemic BP falls). MVP click and systolic murmur begins early (as LV volume is reduced).
HOCM murmur comes early in systole.
Phase VI: S, split widens.
Murmurs on right side are accentuated. (As venous return increases). This manoeuver shouldn't be performed in patients with IHD because of the acconlpanying fall in coronary blood flow.