Introduction
Following surgical augmentation of the right ventricular outflow tract (RVOT), patients with repaired TOF (rTOF) develop moderate to severe pulmonary regurgitation (PR), which causes ventricular dilation due to excess volume load [1]. Patients with rTOF may also have residual pulmonary stenosis (PS) or develop right ventricle-to-pulmonary artery (RVPA) conduit stenosis overtime, resulting in mixed pulmonary disease[2, 3]. The effects of excess volume loading and increased afterload result in abnormal ventricular remodeling and predispose patients to increased risk of ventricular dysfunction, arrhythmia, and death[4]. Mild PS in rTOF is thought to be cardioprotective against the need for pulmonary valve replacement (PVR); however, moderate to severe stenosis necessitates intervention[3]. Recent multicenter prospective data in patients with rTOF demonstrated that right ventricular hypertrophy, right ventricular dysfunction, and older age at PVR is associated with death and sustained ventricular tachycardia (VT)[4]. Re-establishment of a competent pulmonary valve is essential to reverse abnormal ventricular remodeling and mitigate risks[5-8].
Due to increased risk of sudden cardiac death in patients with rTOF, function assessment is paramount for prognosis and risk stratification[9-11]. Myocardial strain imaging by speckle tracking echocardiography (STE) is a unique modality to assess ventricular function[12]. Strain imaging calculates the change in length between two specified areas of the myocardium or lengthening and shortening of the myocardium throughout the cardiac cycle[13, 14]. Studied extensively in heart failure, strain imaging has demonstrated ventricular dysfunction in the setting of preserved EF[15, 16]. In rTOF patients, function by ejection fraction (EF) and right ventricular global longitudinal strain (GLS) have been shown not to improve following reestablishment of a competent pulmonary valve [17, 18]. The goal of this paper was to evaluate the effect of significant pre-procedural afterload on RV and LV GLS by STE in rTOF patients with mixed pulmonary disease following TPVR. We hypothesize that mixed pulmonary disease with significant stenosis will have lower strain magnitude with minimal improvement in RV GLS overtime following TPVR.