The Gallavardin phenomenon is a physical exam finding in patients with aortic valve stenosis. Auscultation at the cardiac apex reveals a murmur that sounds holosystolic and may mimic the murmur of mitral regurgitation.
This is the result of radiation of the murmur of aortic valve stenosis to the apex rather than coexistent mitral regurgitation. This finding is sometimes referred to as "Gallavardin dissociation."
To determine if the apical murmur is indeed due to mitral regurgitation or radiation of the murmur of aortic stenosis, dynamic auscultation can be utilized. Handgrip exercises or transient arterial occlusion increases afterload and will increase the murmur of mitral regurgitation while not changing that of aortic stenosis.