A Comparative Study to Evaluate the Pre and Post-Operative Electrocardiographic and Echocardiographic Changes in Children with Tetralogy of Fallot Undergoing Modified Blalock–Taussig–Thomas Shunt Surgery

BACKGROUND: The modified Blalock-Taussig-Thomas shunt (mBTTS) is a palliative surgical procedure for tetralogy of Fallot (TOF). It enhances left heart filling, which may cause alterations observable in electrocardiography (ECG) and trans thoracic echocardiography (TTE). AIM: This study aims to assess if the ECG and TTE changes in TOF children undergoing mBTT shunt surgery reflect the improved pulmonary blood flow. SETTING: Tertiary care hospital. DESIGN: A prospective observational study. MATERIAL AND METHOD: Thirty-five (35) children diagnosed with TOF, who underwent mBTTS surgery, were included in this study. Pre-operative assessments included a 12-lead ECG and TTE, which were repeated 6 h postoperatively. Hemodynamic and arterial blood gas parameters were also recorded. Statistical analysis was done using a paired t-test. RESULTS: In ECG, pre-operative P axis and QRS axis were found to be 62.05 ± 20.82 and 139.88 ± 22.52, respectively, and they were reduced to 54.94 ± 18.91 (P value of 0.007) and 107.68 ± 27.18 (P value < 0.001) postoperatively. Other parameters, including P wave duration, P wave amplitude in augmented vector lead (aVL), Morris and Marcuz index, were significantly increased in the post-operative ECG. Pre-operative left atrial (LA) reservoir volume and left ventricular end-diastolic volume (LV-EDV) were found to be 5.42 ± 1.28 mL and 10.54 ± 1.78 mL, respectively, and they were increased to 10.44 ± 2.73 (P value ≤ 0.001) and 11.40 ± 1.73 (P value ≤ 0.001) postoperatively. CONCLUSIONS: Changes observed in the hemodynamics, blood gas parameters, ECG, and TTE are consistent with improved pulmonary blood flow.