INTRODUCTION:
In patients who underwent an atrial switch repair (Mustard or Senning
procedures) (1) for complete transposition of the great arteries
(D-TGA), the morphological right ventricle (RV) acts as a systemic
ventricle and the systemic atrioventricular (AV) valve is anatomically
the tricuspid valve (TV). Chronic systemic pressure load on the RV might
lead to ventricular dysfunction, progressive tricuspid regurge (TR), and
heart failure (HF). (2) In patients who underwent atrial switch repair,
the systemic ventricular function is an independent predictor of
exercise capacity. Therefore, atrial switch operations are accompanied
by increased morbidity and delayed mortality, mainly because of heart
failure (3) and ventricular tachycardia due to dysfunction of the
systemic RV (4). In these patients, RV function deterioration is a
progressive and accumulating condition. (5) So, accurate assessment of
RV function and the contractile reserve is mandatory to anticipate the
need for heart failure treatment in these patients.
The systemic RV function can be assessed by several imaging modalities
including angiography, radionuclide imaging, and magnetic resonance
imaging (). (6) However, echocardiography is still used predominantly
for the assessment of RV function, as it is noninvasive, applicable,
available, and inexpensive modality.
Theoretically, stress echocardiography (SE) may deliver more information
about the myocardial contractile reserve, and the behavior of the TR
during stress. Myocardial contractile reserve measured by stress testing
has been defined as the difference of ventricular function at rest and
under loading conditions. As, Dobutamine acts directly and mostly on b-1
adrenergic receptors of the myocardium, producing an increase in heart
rate and contractility, dobutamine stress echocardiography (DSE) can
assess contractile reserve in such patients. (8)
RV has a complex geometry, so, the assessment of systemic RV function
and RV contractile reserve by echocardiography is better to be based on
quantitative assessment. Two-dimensional (2D) speckle tracking
echocardiography () has established as a valuable tool to assess global
and regional myocardial deformation. (9,10) 2D Myocardial speckle
tracking strain (S) is a consistent Doppler and angle independent
technique that quantitatively measures ventricular geometry and systemic
RV myocardial dysfunction. (11-14)
To redefine the role of echocardiography in the functional assessment of
systemic right ventricular contractile reserve in post-Senning children,
we aimed to quantitatively assess the systemic RV contractile reserve in
such patients by interrogating speckle-tracking based global
longitudinal strain (GLS) measurement during Dobutamine Stress
Echocardiography (DSE).