Imaging Strategies for Coronary Sinus Annuloplasty
What Do We Expect from Imaging?
Appropriate evaluation of the coronary venous system and thus appropriate patient selection are key elements of successful device implantation and for avoiding procedural complications. Three major points need to be addressed carefully before implantation:
• the anatomy of the coronary sinus and the great cardiac vein; • the relationship between the coronary venous system and the coronary arteries; and
• the relationship between the coronary venous system and the mitral annulus.
The coronary venous system can be evaluated using three imaging modalities: echocardiography, angiography and computed tomography.
Echocardiography
Transthoracic and transoesophageal echocardiography can provide some visualisation of the coronary venous system. However, echocardiographic assessment is inconstant and allows visualisation of only a small part of the venous system (the distal part or the coronary sinus). Thus, echocardiography cannot be considered a useful technique for the evaluation of venous system anatomy. The usefulness of 3D echocardiography deserves further evaluation, but its spatial resolution remains low and it seems unlikely that it could provide an accurate assessment of the relationship between the coronary sinus and the coronary arteries.
Angiography
Catheterisation of the coronary sinus and retrograde venography has been used since the middle of the 20th century. It should be performed in at least two different views to clearly separate the branches and display the course of the main branches. Coronary venous angiography allows direct measurement of the length and diameter of the coronary sinus and the great cardiac vein. Lengths are measured using dedicated measuring catheters inserted into the veins (see Figure 4) that take into account the curvature of the veins. Diameters, either proximal or distal, can be measured all along the veins using quantitative coronary angiography (QCA), as for the quantification of coronary artery stenosis. These dimensions are crucial for the decision on the size of the device that should be implanted. As a standard method, venous angiography requires a central venous access and carries the risks of an invasive investigation. Therefore, it is usually performed just before and during the implantation. Venography is indeed crucial to guide and monitor the procedure. However, venous angiography cannot provide any assessment of the relationship between the venous system and the mitral annulus, and evaluating the relationship between the coronary arteries and the venous system may be challenging since they are difficult to image simultaneously.
Computed Tomography
Electrocardiogram (ECG)-gated multislice computed tomography has been found to be an alternative.13–16
It provides a superb, detailed and
minimally invasive assessment of the coronary venous system closed to anatomical assessment (see Figure 5). It requires injection of 60–100ml of contrast and usually exposes the patient to a radiation dose of approximately 10mSv.17
Computed tomography
allows a precise evaluation of the coronary venous system anatomy and of the relationship between this venous system and the coronary arteries and the mitral annulus. It is thus the first-choice method for imaging the venous system before device implantation. Magnetic
EUROPEAN CARDIOLOGY
Deep crosses of AIA KL Deep crosses of CA
GCV = great cardiac vein; AIA = anterior interventricular artery ; CA = circumflex artery. Arteries grey; veins black. Source: Bales 2004.20
Coronary sinus P2
Figure 1: Anatomical View of the Relationship Between the Coronary Venous System and the Mitral Annulus
Pulmonary valve
GCV
P1
Aortic valve
Tricuspid valve
P3
GCV = great cardiac vein.
Figure 2: Matrix of Potential Non-intertwined Relationships of the Great Cardiac Vein to the Anterior Interventricular Artery and Circumflex Artery
Relationships of GCV to AIA
GCV origins left of AIA (no crosses of AIA)
Superficial crosses of CA
Relationships of GCV to CA
Proximal crosses of CA Distal crosses of CA AB
CD Deep crosses of CA
GCV origins right of AIA
Superficial crosses of CA
Superficial crosses of AIA
GH Deep crosses of CA
E
F
IJ
Superficial crosses of CA
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