Maximal Oxygen Uptake and Ventilatory Anaerobic Threshold with Pediatrics Aged Group in Non-operated Ventricular Septal Defect and Surgically Repaired Tetralogy of Fallot
Authors: Sulaiman Mohamed Sirajuddin , Reybrouck Tony 
Published: August 2023

Abstract
Objective
1) To determine there is a subnormal exercise performance in children with non-operated ventricular septal defect and operated tetralogy of fallot compared to normal controls and 2) To determine physical activity is an important factor for lower exercise performance in these conditions.

Design and Setting
Retrospective Study. The data were collected from the cardio pulmonary exercise testing and physical activity questionnaire at Department of Pediatrics Cardiology and Department of Cardiovascular Rehabilitation, U.Z. Hospital, Leuven, Belgium.

Patients and Methods
Exercise testing was performed on a treadmill and respiratory gas exchange was measured on a breath by breath technique using mass spectrometry (Marquette MGA 1100, Milwaukee, USA). Exercise testing was performed on a motor driven treadmill. The treadmill speed was set at 5.6 km/hr for children six years or older. The exercise tests started at 0% inclination and systematically increased 2% per minute until the patient was exhausted or symptom-limited or at target heart rate of 170 beats / min were reached. The habitual level of physical activity was measured using standardized physical activity questionnaire.19 subjects with non-operated ventricular septal defect (VSD) (mean (SD) age at testing 11.6 (2.7) years) and 24 subjects who undergone surgically repaired tetralogy of Fallot (TOF) (age 12.7 (2.5) years) performed graded exercise testing and completed physical activity questionnaire were compared with 257 age matched normal controls.

Results
Subjects with non-operated ventricular septal defects compared to normal have mean and standard deviation of ventilatory anaerobic threshold (VAT) averaged 32.70 (6.76) ml kg-1 min-1 and 29.39 (2.68) ml kg-1 min-1 and maximal oxygen uptake( peak vo2) averaged 46.57 (7.83) ml min-1 kg-1 and 47.43 (4.54) ml min-1 kg-1. The unpaired t-test value showed no significance difference for maximal oxygen uptake (p=0.0790) and ventilatory anaerobic threshold (p=0. 7060) in patient with non-operated VSD compared to normal controls. Similarly, Subjects with surgically repaired tetralogy of fallot compared to normal have mean and standard deviation of ventilatory anaerobic threshold averaged 27.77 (3.09) ml kg-1 min-1 and 30.96 (2.76) ml kg-1 min-1 and maximal oxygen uptake (peak vo2) averaged 30.96 (2.76) ml min-1 kg-1 and 50.59 (4.97) ml min-1 kg-1.The unpaired t- test showed a significant difference for maximal oxygen uptake (p = 0.0005) and ventilator anaerobic threshold (p = <0.0001) in patients with operated TOF compared to normal controls.
The habitual level of physical activity was log transformed. There was no significance difference for physical activity (p = 0.9299) in patient with Non-operated VSD [averaged 0.68 (0.11)] compared to Normal controls [average 0.68 (0.07)]. There was a significant difference for physical activity (p =0.0043) in patients with surgically repaired TOF [averaged 0.63(0.12)] compared to normal control [averaged 0.72(0.05)]

Conclusion
Exercise performance was reduced in patients with operated tetralogy of fallot .One of the contributing factor for reduced exercise performance seems to be reduced physical activity. Hence, physical activity has to be encouraged in subjects with reduced exercise performance namely surgically repaired tetralogy of fallot.