We aimed to define differences between systemic right ventricle (RV) in patients with atrial switch procedure for transposition of the great arteries, and congenitally corrected transposition of the great arteries (ccTGA), which remodels early on in life and the subpulmonary RV in patients with idiopathic pulmonary arterial hypertension (iPAH) which remodels later in adulthood to the effects of progressive pulmonary hypertension.

Prospective echocardiographic assessment of consecutive patients with atrial switch procedure, ccTGA, and iPAH attending adult congenital heart program. Right ventricular long axis function by M-mode and tissue Doppler imaging; myocardial performance index; and total isovolumic time (t-IVT), ventricular filling time, and ejection time (ET) were studied and compared with normal left ventricle and RV.

Seventy-eight patients (20 atrial switch, 18 ccTGA, 20 iPAH, and 20 normal) were studied. Right ventricular long axis function was most reduced after atrial switch procedure. Diastolic filling and dysfunction varied across the groups, with atrial switch patients having the lowest myocardial early diastolic (Em) and atrial diastolic (Am) velocities and iPAH patients with the longest t-IVT, shortest filling time and ET, and lowest Em/Am, reflecting predominantly late diastolic filling. Patients with ccTGA had better preserved global systemic RV systolic and diastolic indices.

The RV develops adaptative mechanisms when faced with increased afterload, behaving more like normal left ventricle. This adaptation is closer when present from birth (ccTGA) without facing subsequent surgical insults. In iPAH, the RV adapts poorly, showing prolonged t-IVT and shortened filling and effective ETs, eventually resulting in lower stroke volume and overall poorer prognosis.