Digitization of healthcare has provided opportunities for improving patient care but also has brought with it major security vulnerabilities that could compromise the confidentiality, availability, and integrity of protected health information. This article reviews the proposed distributed system constructs for providing health data security between heterogeneous systems, organizations, and multiple institutions. It categorizes and reviews three approaches to distributed healthcare security: (1) Advanced Encryption Algorithms, including symmetric, asymmetric and homomorphic algorithms for encrypting health information-at-rest and in-transit, and key management mechanisms for secure access to cryptographic material across multiple nodes that may not be trusted; (2) Distributed Storage Systems, including distributed-ledger technology (DLT), distributed file systems, and fragmentation approaches for immutable patient consent and audit trail logging, redundancy to tolerate physical node compromise, and avoiding total infrastructure data loss due to localized security attacks; and (3) Access Control Mechanisms, including multi-factor authentication, role-based access control, attribute-based access control, federated identity management for distributed healthcare organizations, and patient access control and monitoring for distributed threat detection. The distributed model is now more attractive in modern health systems. Perimeter security models do not adequately protect health data. The health data moves through networks connecting hospitals, outpatient clinics, clinical research organizations, insurance companies, and third-party organizations. The proposed framework satisfies regulations according to HIPAA, the General Data Protection Regulation (GDPR), and the Health Information Technology for Economic and Clinical Health (HITECH) Act. The system can be performance optimized to balance between cryptographic strength and system responsiveness. The combination of encryption, decentralized storage, and access control provides defense-in-depth protection against cyberattacks. Future developments, such as artificial intelligence-enabled threat detection, quantum-resistant cryptographic algorithms and models for patient data control will shape how to create secure healthcare systems in our growing digital health networks.