It is well known that the reflected pressure wave in small children returns earlier than that in adolescent. The reason of early return of the reflected pressure wave in infancy is their height. The short distance between heart and reflection point makes the reflected pressure wave returning to the heart earlier. In adult, the early return (during systole) of the reflected pressure wave means disadvantage to cardiac blood supply–workload balance. The purpose of this study was to clarify whether the early return of the reflected pressure wave in small children impairs the cardiac blood supply–workload balance. This study enrolled 37 small left-to-right shunt patients with normal aortic circulation below 15 years of age. The aortic pressure waveform was recorded using a pressure sensor mounted catheter, and augmentation index and subendocardial viability ratio were calculated. The age of patients was 6.1 ± 3.2 years. The augmentation index was 8.7 ± 14.3 % and the index had a negative correlation with patients’ age (r = −0.6243, p < 0.0001). The subendocardial viability ratio, which means the cardiac blood supply–workload balance, was 0.92 ± 0.14 and the index had a positive relationship with patients’ age (r = 0.6435, p < 0.0001). The cardiac blood supply–workload balance gradually improves from infancy to young adulthood. One of the causes of the unfavorable cardiac blood supply–workload balance in infancy would be the accelerated aortic pressure wave reflection due to their short height.