When the interventricular septum is intact, a well-formed nonsystemic ventricle with no outlet is prone to hypertension and hypertrophy after Fontan operation. Herein, we report a patient who had a complex d-transposition of the great arteries palliated over 14 years ago with a Fontan operation and presented with a hypertensive left ventricle (LV) contributing to heart failure. He underwent surgical creation of a ventricular septal defect to decompress the LV and was able to resume his desired lifestyle.