Telemedicine provides a variety of products and services aimed at expediting the flow of digitized patient records. For efficient consultations, it is essential to centralize patient data, enabling easy access to the patient’s medical history during consultations. Consequently, it is crucial for patients to utilize a secure tool with comprehensive security solutions to safeguard their information. In our effort to enhance the security of electrocardiogram (ECG) signals exchanged in telemedicine, we propose a frequency-domain watermarking approach in this chapter. This method involves concealing electronic patient records within corresponding ECG signals. The signal is initially transformed into a two-dimensional (2D) image, and the frequency content is extracted using a redundant discrete wavelet transform (RDWT). The resulting coefficients undergo Schur decomposition, and the watermark bits are incorporated by adjusting the least significant bit of the eigenvalues. Imperceptibility tests demonstrate that this approach generates a watermarked signal closely resembling the original, thereby preserving the diagnostic content. Robustness tests further indicate that the watermark can withstand commonly employed attacks in watermarking.