Possible VSD at 19 weeks?

Today I went in for my anatomy exam and my OB mentioned that the tech was having a hard time identifying the correct function of the heart during the ultrasound. I know she was having a hard time seeing one of the walls (?) or ventricles maybe in the heart. They’re referring me to a specialist to get it looked at more closely to rule out any signs of VSD or Ventricular Septal Defect. Has anyone had this come up in their ultrasound? If so, can you explain your situation and how everything went?

My OB isn’t too worried about it and considered everything else was coming along and growing properly, but did want to look into this situation further to rule out any possibilities.