A previously undescribed type of quadricuspid aortic valve: type H.

The discovery is reported of a previously undescribed type of quadricuspid aortic valve, which was comprised of two equal-sized smaller cusps and two unequal-sized larger cusps. This was proposed as the eighth type of quadricuspid valve, type H. This anatomic variation is the only type of quadricuspid valve that could exist in theory, but has not been previously described. It would therefore, complete the morphological classification of this entity.