Coronary veins: comprehensive CT-anatomic classification and review of variants and clinical implications.

Recent developments in cardiac pacing and trans-coronary vein ablations have demonstrated the increasing value of imaging of the cardiac venous system (CVS), especially computed tomographic (CT) mapping of the coronary veins. In contrast to that for coronary arteries, the literature for coronary veins is scarce. Moreover, a complete, highly efficient, and clinically useful classification of the CVS is not as straightforward as for the coronary arteries. The CVS comprises polymorphous types of venous conduits with notable anatomic variations. Recent anatomic classification divides the cardiac veins into two main groups: tributaries of the greater CVS and tributaries of the lesser CVS, consisting of the thebesian vessels. The greater CVS is subdivided into two groups: coronary sinus and non-coronary sinus tributaries. Imaging information about the CVS in this review is useful for a better understanding of the spatial orientation of the CVS and furthers proper use of the correct nomenclature for this important system. The authors describe the clinical implications of the different imaging techniques for assessment of the coronary veins, where cardiac CT venous mapping has major advantages. The role of CT in anatomic classification, assessment of anatomic variants, and diagnosis of pathologic changes of the CVS is discussed. The authors also underscore the particular role of CT venous mapping for cardiac interventions, especially for left ventricular pacing in cardiac resynchronization therapy and in percutaneous mitral annuloplasty.