WIP 46 - The Unnatural History of the Left Ventricle After Double Switch Operation for Congenitally Corrected Transposition of the Great Arteries with Intact Ventricular Septum: Is Dilation the Norm?

Publication Number: WIP 46.7483

Deepak Gupta, Boston Children's Hospital, Boston, MA, United States; Shanique Sterling-Lovy, Boston Children's Hospital, Boston, MA, United States; Stuart R. Lipsitz, Boston Children's Hospital, Cambridge, MA, United States; Nikhil Thatte, Boston Children's Hospital, Boston, MA, United States

Background: The management of congenitally corrected transposition of the great arteries with intact ventricular septum (ccTGA/IVS) continues to generate debate. In this unique circulation, the morphologic right ventricle (mRV) receives oxygenated blood from the left atrium and pumps it into the aorta, while the morphologic left ventricle (mLV) supplies de-oxygenated blood to the lungs. While patients have normal saturations, the mRV functions as the systemic ventricle leading to a high rate of mRV dysfunction. Anatomic repair consisting of a double switch operation (DSO) – atrial and arterial switch – has been advocated to establish the mLV as the systemic ventricle. A pitfall is the occurrence of mLV dysfunction post-operatively due to sudden exposure to a systemic afterload. The most common outcome metric reported by prior studies has been LV ejection fraction (EF), but when ventricles are exposed to increased afterload, they often dilate to offset the diminished EF. Little is known about the volumetric change experienced by the mLV after DSO.

Objective: The primary objective is to study the volumetric evolution of the mLV following DSO in patients with ccTGA/IVS. Secondary objectives are to determine predictors of mLV dilation and if mLV dilation is associated with acquired systolic dysfunction. We hypothesize there will be increasing indexed LV volume and diminished LV EF after DSO.

Design/Methods: This is a retrospective single center cohort study of patients with ccTGA/IVS who have undergone DSO from 2004 to 2023. Echocardiograms were measured to calculate indexed mLV volumes, mass, sphericity, and EF before DSO and serial times points after DSO. Through chart review, clinical variables at time of DSO were obtained: presence of mLV dysfunction, age at DSO, age at pulmonary artery banding, presence of AV block, and valvar function. Collected data will be analyzed by utilizing a cubic spline to model the mLV dilation over time with paired t-test or Wilcoxon signed-rank test to assess for significance of volume changes and association with outcome metrics.