Elsevier

Cardiovascular Pathology

Volume 25, Issue 5, September–October 2016, Pages 375-380
Cardiovascular Pathology

Original Article
Spatial relationship of coronary sinus–great cardiac vein to mitral valve annulus and left circumflex coronary artery: implications for cardiovascular interventional procedures

https://doi.org/10.1016/j.carpath.2016.06.001Get rights and content

Abstract

Background

The spatial relationship of the coronary sinus–great cardiac vein (CS–GCV) to free posterior portion of the mitral valve annulus (MVA) and left circumflex coronary artery (LCx) has gained importance with the advent of cardiovascular interventional procedures such as percutaneous transvenous mitral annuloplasty (PTMA) and mitral isthmus (MI) ablation.

Methods

In 50 normal (nondilated cardiomyopathy, or non-DCM) and 20 dilated cardiomyopathy (DCM) cadaveric hearts, the diameter and distance from the MVA of CS–GCV and its spatial relationship to LCx along the free posterior portion of the MVA were studied.

Results

The diameter of the CS–GCV increased from the beginning to termination in both non-DCM and DCM cases. The CS–GCV was located farthest from the MVA in the vertical plane in the middle of its course and in the horizontal plane at its beginning. The LCx was located above the CS–GCV in direct contact with the epicardial aspect of MI in 12% non-DCM and 15% DCM cases and was wedged between the CS–GCV and MI in 20% non-DCM and 15% DCM cases.

Conclusions

Knowledge of the separation between the CS–GCV and MVA in the horizontal and vertical planes could help in selecting suitable candidates and the preprocedural prediction of success of PTMA. Awareness of the spatial relationship of LCx with CS–GCV in MI would help to reduce the risk of incomplete MI block due to a heat sink effect or damage to the LCx by direct thermal injury during MI ablation.

Introduction

The arrangement of arterial and venous structures in the free posterior portion of the mitral valve annulus (MVA) has gained importance with the advent of cardiovascular interventional procedures such as percutaneous transvenous mitral annuloplasty (PTMA) and mitral isthmus (MI) ablation [1], [2].

PTMA has emerged as a palliative treatment for mitral regurgitation. The annuloplasty device is placed into coronary sinus–great cardiac vein (CS–GCV) which indirectly reduces the diameter of mitral annulus [3], [4]. Since PTMA exploits the fact that the CS–GCV is located near the MVA, cases with anatomical proximity between the CS–GCV and MVA plane are considered ideal for PTMA [5], [6]. However, most of the part of CS–GCV is located along the left atrial wall at a significant distance away from the true mitral annulus. This may result in ineffective reduction of mitral annular dimensions by the PTMA device [7], [8]. Secondly, left circumflex coronary artery (LCx) lying deep to the CS–GCV is at risk of extrinsic compression with the annuloplasty device inserted into the CS–GCV. Due to these anatomical limitations, all mitral regurgitation patients might not be ideal candidate for this procedure [9], [10], [11], [12].

The MI area is located on the posteroinferior wall of the left atrium (LA) between the left inferior pulmonary vein and the MVA [13]. Catheter ablation for atrial fibrillation is undertaken by complete electrical isolation of the pulmonary veins combined with the creation of a MI conduction block [2]. Blood flow in the epicardial blood vessels such as the CS–GCV and LCx running in the MI area can act as a “heat sink” leading to inadequate heating of the atrial myocardium and reducing the efficacy of radiofrequency ablation at the MI. Such cases may require an adjunctive epicardial ablation from within the CS–GCV to achieve MI block [14], [15]. The LCx, sandwiched between the CS–GCV and MI, not only hinders the success of the epicardial approach due to the “heat sink” effect but also increases the risk of arterial injury [16], [17]. Knowledge of the diameter of the CS–GCV, its distance from the MVA, and spatial relationship with the LCx would make it possible to avoid complications and develop better strategies in PTMA and MI ablation procedures. The aim of the present work was to study the dimensions, course, and spatial relationship of the CS–GCV to the MVA and LCx along the free posterior portion of the MVA.

Section snippets

Methods

This study was conducted on 50 nondilated cardiomyopathy (non-DCM) and 20 dilated cardiomyopathy (DCM) cadaveric heart specimens. Non-DCM group consisted of 32 men and 18 women with an average age of 40.60 ± 10.12 years (age range 18–75 years). The DCM group consisted of 16 men and 4 women with an average age of 36.0 ± 13.9 years (age range 20–55 years). In the non-DCM group, only the cases with noncardiac cause of death were included. Out of 20 DCM cases, 13 had idiopathic DCM and 7 had viral

Diameter of CS–GCV

The average diameter of CS–GCV increased from Z6 to Z1 in both non-DCM and DCM cases (Table 1). In the MI area (Z4), the diameter was 2.64 ± 0.66 mm (1.5–3.8 mm) in non-DCM cases and 2.79 ± 0.95 mm (1.7–4.0 mm) in DCM cases. There was no statistically significant difference (P >.05) in the diameter of the CS–GCV at each zone between the non-DCM and DCM groups as verified by the unpaired t test.

Vertical distance between CS–GCV and MVA

In both non-DCM and DCM groups, the CS–GCV was located along the posterior wall of LA at variable distance

Discussion

Clinical trials (PTOLEMY-2, TITAN, EVOLUTION) have proved that percutaneous CS-based mitral annuloplasty can significantly reduce functional mitral regurgitation with improved quality of life in patients who cannot undergo surgery [18], [19], [20]. Hoffman et al. [21] reported significant reduction of mitral annulus diameter and area after implanting a Viacor PTMA device in a 66-year-old male patient, unsuitable for surgical annuloplasty. Although percutaneous treatment of MR has aroused great

Conclusions

Knowledge of the separation between CS–GCV and MVA in the horizontal and vertical planes could help in selecting suitable candidates and in preprocedural prediction of the success of PTMA. Awareness of the accurate location of LCx relative to CS–GCV would help to avoid the risk of incomplete MI block due to heat sink effect or damage to the LCx by direct thermal injury during MI ablation procedures. The present study reports that in both non-DCM and DCM cases, the CS–GCV is located farthest

Acknowledgments

The authors sincerely thank Mrs. Shallu Jaggi for her help with the data analysis and Mr. Pardeep Singh for his assistance in photography.

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    Funding: The study was supported by the grant from Indian Council of Medical Research, New Delhi, India [Grant No. 3/1/3/JRF-2010/HRD-77(11352)].

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