Early Complication of Mustard Procedure after Late Repair

A 25-year-old woman with complete transposition of the great arteries presented for routine follow-up one year post Mustard procedure. She previously underwent balloon atrial septostomy (Rashkind procedure) early after birth, but her family declined further surgery. She developed progressive pulmonary hypertension early in life, shortness of breath on moderate exertion, followed by progressive exercise intolerance and desaturation (80-85%) over the preceding two years. Pre-operative pulmonary pressure was estimated at approximately 90 mmHg by cardiac catheterization. Subsequently, she underwent a palliative Mustard procedure. Recovery was uneventful with improvement of her functional status and oxygen saturation between 90-95%. Routine transthoracic echocardiogram (TTE) one year postprocedure revealed a severely dilated, hypertrabeculated systemic right ventricle with mild systolic dysfunction and normal sub-pulmonary left ventricular size and systolic function. Additionally, color Doppler showed turbulence at the junction of the upper and lower limbs of the systemic venous baffles suggestive of significant stenosis without baffle leak (Fig. 1, Supplementary movie 1-3). Cardiovascular magnetic resonance confirmed the TTE findings of significant narrowing of the superior vena cava (SVC) and inferior vena cava (IVC) baffles at the venoatrial junction. The pulmonary venous portion of the baffle was patent. The main pulmonary artery and both branches were severely dilated (Fig. 2, Supplementary movie 4-7). Due to the presence of significant narrowing of the SVC/ IVC baffles, cardiac catheterization was recommended to assess the gradients across the stenotic areas and to potentially perform balloon angioplasty/stenting. However, the patient declined as she felt noticeable improvement of her symptoms following the Mustard procedure. Herein we present a rare case describing a known complication of Mustard procedures as early as one year post-operatively, in addition to the Mustard procedure itself, which was delayed until 24 years of age. The etiology of baffle stenosis postMustard procedure is not clear however, speculations include difficult sizing of the baffles in adult heart, localized scarring of the patch at the suture line or perhaps anatomical distortion. Surprisingly, the patient had an improvement in symptoms after the procedure despite this significant subsequent obstruction of the systemic venous pathways.