Supracristal Ventricular Septal Defect

A supracristal (also known as subpulmonic or doubly committed) ventricular septal defect (VSD) lies above the crista supraventricularis and below the pulmonic valve, such that the aortic and pulmonary valves are in fibrous continuity.

Supracristal ventricular septal defects are the least common of the VSDs, comprising between 2%-3% of cases. They are hard to detect on echocardiography, but have a typical appearance on angiography and MRI.

On angiograms in the frontal projection, a jet of contrast material can be seen passing from the left ventricle beneath the left aspect of the aortic valve into the outflow tract of the right ventricle just below the pulmonary valve.

Axial MR images at the level of the right ventricular outflow tract reveal a defect between the base of the aorta and the upper posterior aspect of the right ventricular infundibulum. Cine MRI will a flow jet in the distal right ventricular outflow tract into the main pulmonary artery.

Supracristal ventricular septal defects are seen in is association with:

• Aortic regurgitation
• Balloon-like dilatation of the right coronary sinus
• Prolapse of the right coronary cusp into the right ventricular infundibulum
• Right coronary sinus-right ventricular fistula
• Double outlet right ventricle with supracristal ventricular septal defect (Taussig-Bing anomaly).

References

• Bremerich J, Reddy GP, Higgins CB. MRI of supracristal ventricular septal defects. J Comput Assist Tomogr. 1999 Jan-Feb;23(1):13-5.
• Jaffe RB, Scherer JS. Supracristal ventricular septal defects: spectrum of associated lesions and complications. AJR Am J Roentgenol. 1977 Apr;128(4):629-37.
• Miller LR, Nemeth M, Flamm SD, Sung C, Stainback RF. Supracristal ventricular septal defect. Tex Heart Inst J. 2006;33(1):96-7.