UBC Theses and Dissertations
Using tissue doppler imaging during exercise to assess ventricular function and wall motion in childhood survivors of acute lymphoblastic leukemia De Souza, Astrid-Marie
BACKGROUND: Childhood survivors of Acute Lymphoblastic Leukemia (ALL) may be at risk of cardiotoxicity as a consequence of their treatment with anthracyclines. Stress echocardiography has been well established as a method to detect latent cardiac dysfunction, indicative of cardiotoxicity. Tissue Doppler Imaging (TDI) is a new echocardiographic technique that can be incorporated into current stress echocardiography protocols to potentially enhance our ability to detect early changes in cardiac function in ALL patients treated with anthracyclines. PURPOSE: To determine if ALL patients have abnormal wall motion responses to exercise. METHODS: Thirteen ALL patients (11 yrs; 9-14 yrs) and fourteen healthy children (10.5 yrs; 9-16 yrs) were studied. ALL patients were treated with a median cumulative anthracycline dose of 150 mg/m² (150-175 mg/m²). TDI was performed during semi-supine cycle ergometry at rest, peak exercise, immediately post- and 3 minutes post-exercise. The parasternal long axis (posterior wall=POS) and apical 4-chamber (lateral wall=LAT, interventricular septum=SEP, and right ventricular wall=RV) views were used to obtain measurements. Tissue velocities (S' E', A'), strain (ε[sub sys]), and tissue tracking (TT) were measured. TDI analyses were performed off-line. Oxygen capacity (VO₂) was measured concurrently. A Wilcoxon-Rank Sum test was used to determine whether there were differences between ALL patients and controls and between each stage. Data was analyzed using SPSS 12.0 Statistical Software (SPSS Inc., Chicago, IL). RESULTS: No significant differences were found between ALL patients and controls at rest, peak, immediately post-, and 3 minutes post-exercise for all TDI variables. S' and A' significantly increased in all walls, in both groups. E' significantly increased in the POS and RV, but not in the LAT and SEP. Strain did not increase with exercise in any of the segments evaluated. A significant increase in TT was only seen in the POS wall of the controls (p≤0.003); however, values were approaching statistical significance in the POS of ALL patients (p=0.004). Peak VO₂ was similar between groups. CONCLUSIONS: I have shown that TDI variables and VO₂ peak are similar in ALL patients and controls. Further studies are needed to determine the clinical usefulness of TDI during stress echocardiography.
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