Differential diagnosis
The murmur of VSD is most commonly discovered shortly after birth. Undocumented holosystolic murmurs in the adult population is therefore more likely to be caused by Mitral Regurgitation or Tricuspid Regurgitation. Hypertrophic Cardiomyopathy should also be considered and squatting maneuver performed. (see HCM)

Also, even though Aortic Stenosis has a midsystolic murmur, the tendency is uncertainty in establishing a holosystolic murmur from a midsystolic murmur. Therefore Aortic Stenosis,  Pulmonary Stenosis and coarctaction of aorta should also be considered.