Peak dobutamine stress echocardiography (DSE):
At peak DSE, 17 (54.84 %) patients developed dyspnea and were in New York Heart Association (NYHA) function class II/III. Only, two (6.45%) patients developed arrhythmias in the form of infrequent atrial ectopics.
There was no significant decrease in oxygen saturation from 97.75 ± 1.50 % at rest to 96.25 ± 1.41 % at peak DSE (P = 0.07). Despite, heart rate increased significantly from 98.45 ± 15.76 bpm at rest to 121.50 ± 17.20 bpm at peak stress (P = 0.021*), the patient showed chronotropic incompetence as 12 (38.721%) patients did not reach the expected target heart rate for age at peak stress (173.56 - 178.77 bpm), and 19 (61.29%) patients underwent immediate dobutamine withhold due to appearing of symptoms (dyspnea or arrhythmia) during the examination. Blood pressure increased significantly from 106.50 ± 13.09 / 72.50 ± 10.24 mmHg at rest to 132.25 ± 13.03 / 82.50 ± 12.51 mmHg at peak stress (P = 0.042*).
With peak DSE, no patients developed pulmonary or systemic baffle stenosis or obstruction in the LVOT. Tricuspid systemic valve regurge was more apparent post-stress to be; mild only in 11 (35.48 %) patients, moderate in 15 (48.39 %) patients, and severe in 5 (16.13 %) patients.
Despite RV EDV showed no significant decrease from 53.95 ± 10.31 ml at rest to 50.25 ± 8.84 ml at peak stress (P = 0.31), RV ESV significantly decreased from 32.15 ± 9.70 ml at rest to 30.35 ± 9.50 ml at peak stress (P =0.010*).
The contractile reserve was not evident as measured by RV EF that increased but non significantly from 40.13 ± 2.93 % at rest to 42.47 ± 2.80 % at peak stress (P = 0.063), with <5% improvement in RV EF. Figure (1) showed a non-significant (<5%) increase in RV EF by Simpson’s method in a post-Senning 13 years old child from 39% at rest to 42% at peak stress Echocardiography.
However TAPSE and RV GLS showed that there is still a contractile reserve in Senning patients in the childhood age; TAPSE increased significantly from 13.81 ± 1.26 mm basally to 15.34 ± 2.61 mm at peak stress (P = 0.003*), and RV GLS improved significantly > - 2% from -11.89 ± 1.31 % basally to -15.78 ± 0.93 % at peak stress (P <0.001*). Dobutamine stress echocardiography and contractile reserve in Senning patients were shown in table (2). Figure (2) showed the quantitatively assessed contractile reserve in a Senning patient child of 11 years old with an improvement of RV GLS from -11.2 % at rest to -15.6 % at peak dobutamine stress Echocardiography.
19 (61.29%) patients showed masked RV contractile reserve with >2% improvement in RV GLS despite < 5% improvement in RV EF. These patients underwent anti-fibrotic and anti-failure medications in the form of angiotensin-converting enzyme inhibitors/ angiotensin receptor blockers (ACEI/ARBs), spironolactone therapy, and sometimes beta-blockers (In patients without symptoms of heart failure).