How far is the left circumflex coronary artery from the mitral annulus?

When too much closeness harms: circumflex artery injury during mitral valve surgery

Occlusion of the left coronary circumflex artery (LCX) during surgical procedures of the mitral valve is an infrequent but potentially life-threatening complication (1-3). Due to its close anatomical relationship to the posterior mitral valve annulus, there is a relevant risk of causing a stenosis or an occlusion of the left circumflex artery, especially by surgical annular sutures. The perioperative clinical course is heterogeneous, ranging from-initially-asymptomatic or solely electrocardiographic abnormalities to cardiogenic shock. Both severely impaired ventricular contractility or malignant arrhythmia may potentially lead to a weaning failure from cardiopulmonary bypass (CPB) and eventually result in chronic heart failure with persistently reduced ejection fraction. Possible therapeutic strategies include the immediate reopening of causal sutures, aortocoronary bypass grafting or percutaneous coronary intervention (PCI), yet PCI seems to be the preferred method at present.

Acute iatrogenic complications after mitral valve repair

BACKGROUND AND AIM OF THE STUDY

Mitral valve repair is the procedure of choice to correct mitral regurgitation. However, some dangerous iatrogenic complications can occur at the end of the procedure. Therefore, we sought to review the most frequent and clinically relevant acute iatrogenic complication following mitral valve repair.

METHODS

A thorough review of the literature has been performed. Criteria for considering studies for this non-systematic review were as follows: observational and interventional studies investigating the acute iatrogenic complications following mitral valve repair, and essential review studies pertinent to the topic.

RESULTS

The most frequent is the systolic anterior motion. Due to a systolic dislocation of the anterior leaflet toward the outflow tract, it causes both obstruction of the outflow tract and mitral regurgitation. Often it is due to excess of catecholamines or to reduced filling of the left ventricle but sometimes needs further surgical maneuvers, focused on moving posteriorly the coaptation line. It can be obtained by shortening the posterior leaflet or increasing the size of the ring or applying an Alfieri stitch to limit the movements of the anterior leaflet. Another complication, often underdiagnosed and potentially lethal, is the injury of the circumflex artery that happens at the level of the anterolateral commissure or P1 zone. Two mechanisms are involved. The first one is the direct injury of the artery by a stitch (roughly 25% of the patients present a distance artery-annulus <3 mm. The second one is the distortion of the artery, attracted toward the annulus by a misplaced stitch. The attraction causes kinking with stenosis of different degrees till functional occlusion. However, the artery has to be far from the annulus and the atrial tissue has to be stiff and resistant, as after an infective process, to move the circumflex artery toward the annulus without tearing. Positioning the stitches very close to the mitral leaflets in the dangerous area is the only prevention to the complication. The treatment in the operating theater is partial or total removal/reimplantation of the annular sutures or coronary artery bypass grafting to the circumflex area. If the injury is demonstrated only after coronary angiography, percutaneous revascularization can be attempted before further surgical treatment.

CONCLUSIONS

Acute iatrogenic complication after mitral repair exists and may compromize patient outcome. Raising awareness about these issues, the precautions to prevent them, and the manners of resolution is therefore mandatory.

Computed tomography to identify risk factors for left circumflex artery injury during mitral surgery

OBJECTIVES

Cases in which the left circumflex coronary artery (LCX) runs close to the mitral annulus are considered high risk for LCX injury during mitral surgery. We investigated the anatomical relationship between the LCX and the mitral annulus using 3-dimensional (3D) computed tomography (CT).

METHODS

We constructed 3D-CT images of the LCX and the mitral annulus before surgery in 122 patients with mitral regurgitation (MR). We classified coronary dominance by 3D-CT and MR aetiologies (degenerative, atrial functional MR, ventricular functional MR and Barlow's disease) using echocardiography. We detected the point on the mitral annulus closest to the LCX (X point) and measured the minimum distance from the LCX to the mitral annulus (mCAD). We judged whether atrioventricular disjunction existed using CT. We also investigated the factors affecting mCAD and examined how coronary dominance and MR aetiologies relate to the location of the X point.

RESULTS

The median mCAD was 4.2 mm (range 0.9-11.4 mm). Considering coronary dominance and MR aetiologies, mCAD was shorter in patients with left coronary dominance and Barlow's disease. The X point mostly existed on the lateral side of the posterior annulus, but it sometimes existed on the medial side. Multiple regression revealed left dominance and mitral annular disjunction as significant factors affecting mCAD (P = 0.01).

CONCLUSIONS

The anatomical relationship between the LCX and the mitral annulus can be recognized using superimposed 3D-CT images. This approach is useful to avoid LCX injury in mitral valve surgery since the X point varies between patients.