Catheter-based optical approaches for cardiovascular medicine: progress, challenges and new directions

Catheterization of the heart is crucial for many diagnostic and therapeutic procedures in cardiovascular medicine. In this review, we discussed developments of catheter-based optical tools and approaches for cardiovascular medicine. We provided a background in gross and microscopic anatomy of the normal and diseased heart. We overviewed optical properties of cardiac tissues, such as scattering, absorption and fluorescence, and related optical properties to tissues constituents. Furthermore, we introduced optical modalities for tissue characterization, in particular, spectroscopy, confocal, multi-photon and light sheet fluorescence microcopy, and optical coherence tomography. We then surveyed example applications in cardiovascular medicine and contrasted established clinical tools and approaches with catheter-based optical approaches and tools. First, we explored assessment of heart transplant rejection and reviewed alternative catheterized optical approaches. Rejection is commonly assessed using endomyocardial biopsy, i.e. the excision and histological assessment of tissue samples. A further application is atrial fibrosis mapping. Atrial fibrosis is an important predictor for prognosis of atrial fibrillation patients, yet clinical tools for fibrosis mapping in patients are lacking. We surveyed clinical tools for assessing catheter ablation of the heart, which is an indispensable therapy for arrhythmia. Last, we discussed methods and protocols for guiding coronary angioplasty and stent placement. For all applications, we explored the current and potential role of catheterized optical tools. We concluded with a discussion of technical challenges and open questions related to clinical translation of the catheter-based optical approaches. Our review stressed the potential of catheterized optical tools to improve diagnosis and treatment of patients with heart disease.