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Anatomical variants of left circumflex artery, coronary sinus and mitral valve can determine safety of percutaneous mitral annuloplasty.

BACKGROUND
The anatomical variants of the relations of the left circumflex artery (LCx) andthe coronary sinus (CS) determine the safety of percutaneous mitral annuloplasty (PMA) as an occlusion of the LCx and its consequences might occur in some cases. Thus, knowledge ofthe anatomy of cardiac anatomy and any variations are important for surgeons.


METHODS
In 320 (126 women, age 59 ± 11) patients, a 64-slice computed tomography (MSCT) (Aquilion 64) was performed due to a suspicion of coronary artery disease. A scanwith ECG-gating was performed using a slice thickness of 0.5 mm during a breath-hold. The helical pitch was 12.8, rotation time: 0.4 s and average tube voltage: 135 kV at 380 mA.100 mL of non-ionic contrast agent was given in three phases at an average rate of 4.5 mL/s.In each case, ten 3D volume rendering and 2D multiplanar reconstructions of the vessels were created (Vitrea 2).


RESULTS
The CS was visualized in all cases and the LCx in 315 (98.4%). In 302 (95.8%)cases, the CS was the dominant vessel; in 10 (3.17%) cases both vessels were equal and the LCxwas dominant in only 3 (0.9%) cases. 52 anatomical variants were identified; 3 of them werethe most common (in 164/315 cases; 50.8%). The CS usually lies above the atrioventricular(AV) sulcus (239-75.9%) and the LCx within the AV sulcus (173-54.9%). In 235 (74.6%)cases, the LCx was closer (than the CS) to the mitral valve. It was found that in 78 (24.7%) cases, the LCx was beneath the CS in selected phases (a risk of LCx occlusion by a PMA device).The LCx closer to the mitral valve, which is considered as a safe feature for PMA, was observed in only 75 (23.8%) of the cases. The most dangerous pattern was found in 19 cases(6.1%) - 2 or 3 CS/LCx crosses.


CONCLUSIONS
The huge anatomical variability of the anatomy of the CS/LCx strengthens the role of MSCT before PMA implantation.