J Vet Cardiol. 2025 Dec 2;64:1-13. doi: 10.1016/j.jvc.2025.11.006. Online ahead of print.
ABSTRACT
INTRODUCTION/OBJECTIVES: The coronary sinus (CS) and great cardiac vein (GCV) are crucial in cardiac electrophysiology and can be arrhythmogenic in humans. In horses, CS/GCV catheterisation is increasingly performed for arrhythmia diagnosis and treatment. Improved anatomical understanding of these structures is needed to clarify relationships to surrounding structures.
ANIMALS, MATERIALS AND METHODS: Postmortem examinations of 64 adult warmblood equine hearts were carried out. Middle cardiac vein and vein of Marshall ostia locations were described. Right atrial myocardial sleeve (MS) length was measured from the CS ostium. In 23 horses, CS/GCV length in the coronary groove and distance to left atrial myocardium (LAm), left ventricular myocardium (LVm) and mitral annulus were measured at eight levels. The MS and LAm relationship was assessed histologically.
RESULTS: The middle cardiac vein opened more frequently into the right atrium than the CS, with the vein of Marshall consistently present near the Vieussens valve. Mean (standard deviation) CS length was 28 (13) mm. Right atrial MS extended 52 (18) mm into the GCV in 63 of 64 horses. The mean CS/GCV length was 240 (36) mm in the coronary groove. The GCV-LAm distance changed from median [interquartile range] of 10 [6] mm (CS end) to 2 [2] mm (mid-left free wall) to 32 [13] mm near the paraconal interventricular sulcus with opposite LVm relationships. Histology showed myocardial connections between MS and LAm.
STUDY LIMITATIONS: The limitations of this study included postmortem material from warmblood horses, single-observer measurements and lack of in vivo assessment.
CONCLUSIONS: Coronary sinus/GCV trajectory is important for optimal catheter positioning. Right atrial MS might contribute to arrhythmogenesis, and tributary variations may impact CS/GCV catheterisation in horses.
PMID:41422744 | DOI:10.1016/j.jvc.2025.11.006