Steerable catheters in cardiology: Classifying steerability and assessing future challenges

Objective: This review aims to provide a structured classification of the underlying steering mechanisms in steerable catheters and to assess their future challenges. Methods: Existing, patented, and experimental designs of steerable catheters are classified with respect to their steerability. Subsequently, the classification is used as a tool for defining future requirements and challenges for steerable cardiac catheters. Results: The results of the classification provide two categories of steering at a fundamental level: 1) Force generation in the tip and 2) force transmission to the tip. The former group consists of force generating steering mechanisms as a result of 1) electric, 2) thermal, and 3) magnetic actuation. The latter group comprises force transmitting steering mechanisms as the result of 4) hydraulic chamber actuation or 5) mechanic cable actuation. Each category can be further subdivided into multiple subcategories. Future requirements and challenges are found for steering and positioning capabilities, cardiac applications and safety, and miniaturization potential. Conclusion: A structured classification is presented which identifies the different steering mechanisms in steerable catheters. The classification proves to be a useful tool in determining future requirements and challenges, being invaluable for future application-driven design. Significance: Using the applied classification as a tool for future design will not only provide insight into previously applied steering technology, it will identify new and unexplored options too. Additionally, insight into the requirements and challenges for catheter steering toward and inside the heart, will allow more dedicated systems, allowing intervention- and patient-specific instrument manipulation.