Final answer:
The regurgitant jet area of less than 1.0 cm2 in a prosthetic aortic valve can be explained by ball variance, which refers to the improper seating of the ball valve within the aortic valve chamber.
Step-by-step explanation:
The regurgitant jet area of less than 1.0 cm2 in a prosthetic aortic valve can be explained by ball variance. Ball variance refers to the improper seating of the ball valve within the aortic valve chamber, which can cause a small regurgitant jet area. This is a common issue with prosthetic valves and can lead to backflow of blood and disruption of normal blood flow.