Dobutamine stress echocardiography (DSE):
After six hours fasting, the dobutamine stress test was used to assess
all echocardiographic parameters after dobutamine infusion [Started at
2.5 µg/kg/min, and increased gradually every 3 min and maximally to 40
µg/kg/min (Atropine was not given as it was unsafe and probably
unnecessary in such age group)]. Dobutamine stress endpoints were
taken with reaching the predicted target heart rate for age [85% (220
minus age in years)], starting symptoms (Dyspnea and or arrhythmia),
or reaching 40 µg/kg/min dobutamine dose. Heart rate and blood pressure
were recorded at every stage. Baseline and peak dose images were stored
and compared offline. (8)
A normal response to dobutamine infusion was demarcated as a progressive
increase in myocardial thickening and hyperdynamic wall motion as
assessed by RV EF, RV GLS, and TAPSE from rest to peak dose dobutamine
infusion (negative DSE). An abnormal response to dobutamine infusion was
clarified as a reduction in myocardial thickening or wall motion at any
stage of the dobutamine infusion compared with the previous stage
(positive DSE). (8) Global contractile reserve was defined as
improvement > 5% in RV EF, >2% in RV GLS,
and/or to near normal parameter Z values in TAPSE. (8) Any change in
cardiac function (improvement or worsening in RV EF, RV GLS, TAPSE),
LVOT gradients, and severity of TR was reported.