Secure management of Critical National Infrastructures (CNI) is a burning challenge to any state. As a CNI, Electronic Healthcare System (EHS) infrastructure records citizens' medical records, raising security and privacy concerns. Traditional EHS functions independently where patients' records are recorded and maintained in centralized systems that produce massive redundant data. Due to the noncoherence of these systems, data atomicity is not maintained; hence research results based on these data create questioning. Moreover, medical records are valuable for research but cannot be public due to security and privacy. Blockchain (BC) is currently considered a potential solution for the challenges. Blockchain can integrate every independent EHS as a bridging platform. The solution can ensure data uniqueness and overcome security issues. The prime difficulties for the integration are data synchronization of the traditional EHS and BC-based EHS. Furthermore, the autonomous interoperability between SQL and NoSQL database used in typical EHS and BC-based EHS, respectively, is a prime challenge. Therefore, this research proposes a Blockchain-based framework that bridges Traditional E-Health Systems(TEHS) and allows uninterruptible data exchanges between two systems, even for archive medical records. Beyond that, the framework shows an elevated way to overcome a single point of failure, data security, access control, etc., issues in a centralized system. Finally, the testbed implementation justifies the proposed architecture.