<prompt> Murmur increasing with Valsalva manouvre -Ventricular septal defectHCMhyperophic cardio myopathyMitral stenosisAoic stenosis  <response>: Increases 65 of the time with hyperophic cardiomyopathy; decreased 30 of the time; Increased intensity 65 sensitive and 96 specific for hyperophic cardiomyopathy as opposed to other lesions Most other murmurs decreased intensity during Valsalva. Physiologic explanation: murmur intensity increases with decreased LV volume because of increased proximity of septum and mitral valve; decreased venous return with Valsalva Ref Harrison 20th edition pg 1446 