Severe Subpulmonic Obstruction by Accessory Valve Tissue Mimics a Fallout's Tetralogy Physiology

Objectives: We report a case of severe subpulmonic obstruction in a neonate due to accessory valve tissue, miming a Tetralogy of Fallot physiology diagnosed by transthoracic echocardiography and surgically repaired. To our knowledge, an accessory aberrant dysplastic valve tissue in the right ventricular outflow tract (RVOT), associated with an atrial septal defect Ostium II and perimembranous ventricular septal defect, has not been described previously in a neonate.

Methods: A 4-day-old boy was referred to our Department for severe cyanosis evaluation. On examination, the baby had a heart rate of 150 beats per minute, blood pressure of 90/58 mm Hg and a systemic oxygen saturation of 65 to 75% in room air. Cardiovascular examination revealed a systolic murmur of grade 3/6 in the left lower parasternal area. Transthoracic echocardiography revealed an accessory aneurysmatic tissue oscillating within the right ventricular outflow tract (RVOT), resembling an “hammock,” one cm below the pulmonary valve and a max velocity of 4.5 to 5 m/s across the RVOT. In addition an atrial septal defect (ASD) ostium II with right to left shunt, a large perimembranous ventricular septal defect (VSD), mild infundibular hypertrophy and closed ductus arteriosus. In view of worsening cyanosis, we scheduled the child for surgery. The surgical technique involved a midline sternotomy, cardiopulmonary bypass with ascending aortic, bicaval cannulation, and cardioplegic arrest. Surgery was performed from the right atrium. Inspection revealed an ASD ostium II, a normal tricuspid valve, a large perimembranous VSD. In the RVOT, an accessory redundant dysplastic valve-tissue, resembling a pulmonary valve without connection with the tricuspid, the VSD or the pulmonary valve and mild infundibular hypertrophy were seen. Resection of the aberrant valve, of the infundibular hypertrophy and closure of the ASD and VSD were performed. The histological examination, confirmed the diagnosis of dysplastic valve tissue.

Conclusion: Isolated subpulmonary membranes are extremely rare and only two cases have been reported in the literature. To our knowledge an accessory aberrant dysplastic valve tissue oscillating within the RVOT, resembling an “hammock,” associated with ASD ostium II, perimembranous VSD and clinically miming tetralogy of Fallot physiology was never previously reported.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
19 February 2021