Monitoring myocardial stiffness changes with shear wave elastography (SWE) has promising potential for assessing chemotherapy-induced cardiotoxicity for pediatric cancer patients. While ultrasound B-scan with adult cardiac probes on children is commonly acceptable, SWE can be challenging due to the narrow intercostal spaces of children, which hinders the effective transmission of the push beam and detection beam for shear wave generation and shear wave detection. This study aimed at addressing this challenge by implementing cardiac SWE on a pediatric cardiac probe (P7-4) with pulse-inversion harmonic imaging (PIHI) and time-aligned sequential tracking (TAST). The performance of the proposed pediatric cardiac SWE sequence (P7-4 PIHI-TAST) was systematically compared with an adult cardiac transducer equipped with the same PIHI and TAST cardiac SWE sequence (P4-2 PIHI-TAST), and a pediatric cardiac SWE sequence with fundamental imaging TAST shear wave detection (P7-4 Fundamental-TAST). In vivo transthoracic scans in healthy pediatric volunteers demonstrated substantial improvement of shear wave signal quality using the P7-4 PIHI-TAST sequence, as compared to the adult P4-2 PIHI-TAST sequence and the pediatric P7-4 Fundamental-TAST sequence. The results showed higher increase in SWE success rate among younger children when using the pediatric transducer. Also agreeing with previous studies, this study demonstrated that PIHI shear wave detection could substantially improve the shear wave signal quality as compared to fundamental imaging shear wave detection.