The inferior radiolucent area within the cardiac silhouette: validation as a landmark for coronary sinus catheterization.
BACKGROUND
Catheterization of the coronary sinus (CS) plays a preponderant role in device implantation and electrophysiology. Nevertheless, catheterization of this structure can be time-consuming and is related to operator experience. An inferior radiolucent area of the cardiac right anterior oblique (RAO) view has been suggested as a landmark to guide CS catheterization. However, the true relationship of this area with the CS ostium (CSO) has not been studied.


METHODS
Thirty-five consecutive patients who underwent right coronary angiography were prospectively enrolled in the study. Fluoroscopic images of the heart in the right anterior oblique, both immediately before and during the venous phase of right coronary angiography, were recorded and digitally stored. Postprocedure measurements of the inferior radiolucent area within the cardiac silhouette and, subsequently, the distance of this area to the CSO, were performed by two independent observers.


RESULTS
A radiolucent area of 9.5 +/- 3.0 x 11.0 +/- 3.4 mm was identified in the inferior annulus by the two evaluators in all patients. No significant differences in the dimensions of this area were found between the two observers. The CSO was 9.6 +/- 7.2 mm superior and 0.1 +/- 9.0 mm posterior to the radiolucent area and no statistically significant differences were found between the two observers.


CONCLUSION
An inferior radiolucent area can be identified within the cardiac silhouette in most patients in the RAO view. This area is slightly anterior and inferior to the CSO and can be used for catheterization guidance of this latter structure.