Objectives:

This angle is used primarily to demonstrate the Left Main and the Circumflex arteries, and is the best view for demonstrating the proximal Obtuse Marginal branch. The Left Anterior Descending artery is also seen however is often overlapped by the Diagonal branches. Acquisition time should be long enough to obtain adequate contrast filling of the distal arteries, and if necessary pan to the anatomical right to visualise collateral filling of the Right Coronary artery. Visualising the right coronary artery filling distally may assist Cardiologist of the possible lesion length occurring in that artery.

Catheter Positioning:

Ensure the catheter is located in the top left corner of the screen.

Alternatives:

More CAU (eg. RAO 30 / CAU 40):

This decreases the foreshortening of the proximal circumflex improving visualisation. The distal circumflex can be foreshortened and overlapped by distal branches. Foreshortening of the LAD occurs mid /distal with overlap of the diagonal branches.

Less CAU (eg. RAO 30 / CAU 10):

Increases foreshortening of proximal circumflex, however improves visualisation distally by separating the distal branches. The obtuse marginal is often overlapped by large septals from the LAD or diagonal branches.

More RAO (eg. RAO 40 / CAU 20):

This separates the diagonal branches further from the LAD, demonstrating them inferior to the LAD. This view can also improve visualisation of the mid / distal Obtuse Marginal branch

Less RAO (eg. RAO 10 / CAU 20):

This separates the diagonal branches further from the LAD, demonstrating them superior to the LAD.

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