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.