Types of VSDs

Q: What is Gerbode defect, a variant of Ventricular Septal Defects (VSDs)?



Answer: Most of the books/articles/experts describe four types of VSDs. The objective of this question is to highlight a technically 5th type or a variant of VSD.

Type 1:  Infundibular VSD:  This is due to the deficiency in the septum above and anterior to the crista supraventricularis, beneath the aortic and pulmonary valves. Due to location it has given names as supracristal, subarterial, subpulmonary, conal, or doubly-committed VSD. As it is very close to aortic valve, clinically it is more prone to cause progressive aortic regurgitation. 

Type 2: Membranous VSD: This is the most common type of VSD and is due to deficiency of the membranous septum. When muscular septum gets involved it is called peri or paramembranous VSD. 

Type 3: Atrioventricular or canal VSD: This is due to the deficiency of the inlet septum located beneath both mitral and tricuspid valves. 

Type 4: Muscular defects: These are bordered only by muscle within the trabecular septum. 

Gerbode defect: This is not counted as Type 5  but technically considered as a VSD. This is due to deficiency of the membranous septum separating the left ventricle (LV) from the right atrium. This is the least common type but when present causes LV-to-right atrial shunt.


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References:

1. Tidake A, Gangurde P, Mahajan A. Gerbode Defect-A Rare Defect of Atrioventricular Septum and Tricuspid Valve. J Clin Diagn Res. 2015;9(9):OD06–OD8. doi:10.7860/JCDR/2015/14259.6531

 
2. Saker E, Bahri GN, Montalbano MJ, et al. Gerbode defect: A comprehensive review of its history, anatomy, embryology, pathophysiology, diagnosis, and treatment. J Saudi Heart Assoc. 2017;29(4):283–292. doi:10.1016/j.jsha.2017.01.006