Bridging Blockchains: A Comprehensive Analysis of Interoperability Challenges and Multi-Blockchain Architectures

The rapid evolution of blockchain technologies has intensified the need for interoperable and multi-chain infrastructures, particularly in domains that rely on secure and auditable data management, such as healthcare. This paper presents a structured literature review on blockchain interoperability and multi-blockchain architectures, with emphasis on their applicability to healthcare data-sharing systems. Through a systematic examination of existing models—including Polkadot, Hyperledger Cacti, and Cosmos—we organize and analyze the main approaches proposed in the field. The study offers three primary contributions: (i) the systematization of the key technical and organizational challenges involved in enabling interoperability across heterogeneous blockchains; (ii) the mapping and classification of current solutions and architectural strategies reported in the literature; and (iii) the identification of multi-blockchain consensus as a promising and underexplored research direction for reducing external trust assumptions in cross-chain operations. The findings aim to support researchers and practitioners in understanding current limitations and guiding future investigations on interoperable blockchain ecosystems. healthcare studies [22, 31, 34]. The core challenge is enabling effective data exchange across these isolated systems while preserving blockchain’s intrinsic security and trust [5, 14, 34]. Interoperability is now a fundamental requirement for robust solutions in critical domains [23]. This paper provides a holistic overview of multi-blockchain research, focusing on critical trends and challenges relevant to global scientific and industrial communities. Our work is structured as: • Related Work: A review of existing literature on blockchain interoperability and multi-blockchain architectures. • Fundamentals: Conceptual foundation of blockchain, consensus mechanisms, and cross-chain communication principles. • Multi-Blockchain Architectures: Analysis of prevalent cross-chain communication approaches, including Relay models, Polkadot, Hyperledger Cacti, and Cosmos. • Trends and Challenges: Identified challenges such as communication across heterogeneous systems, shared consensus mechanisms, regulatory compliance, and decentralized identity verification. • Conclusion: Summarizes key findings and outlines future research directions.