After familiarizing yourself with the concepts and terminology introduced in the section Angulation, you can use this section to see examples of standard viewing angles. Because of differences in individual anatomy, the exact angles of angulation often need to be adjusted to optimize images.

These angles are by no means exhaustive or definitive. Rather, this is a starting point to understand commonly used projections.

Guiding principles

<aside>

• Cranial is best for inferiorly located vessels (PDA, PL, distal LAD/LCx/RCA)
• Caudal is best for superiorly located vessels (LM, proximal LAD/LCx/RCA)
• RAO is best for left sided vessels (LCx, LAD)
• LAO is best for right sided vessels (RCA) </aside>

By coronary segment

• Left main coronary artery
  • Ostium: LAO caudal, LAO cranial
  • Body: AP caudal, LAO caudal (particularly for LAD/LCx bifurcation)
• Left anterior descending
  • Proximal: LAO caudal, AP caudal
  • Mid: RAO cranial, AP cranial, LAO cranial (particularly for diagonal bifurcation)
  • Distal: RAO cranial
• Left circumflex coronary artery
  • Proximal: RAO caudal, LAO caudal, AP caudal
  • Mid: RAO caudal (particularly for OM bifurcation), LAO caudal, LAO cranial
  • Distal: RAO cranial, RAO caudal
• Right coronary artery
  • Ostium: LAO caudal
  • Proximal/mid: LAO, LAO caudal
  • Distal: LAO cranial, AP cranial (particularly for PDA/PL bifurcation)
  • Posterior descending artery/posterolateral: RAO

By angiographic projection

Left circulation

RAO caudal

The base will be to the left of the screen and the apex to the right. The anterior heart is toward the top of the screen, and the inferior heart is toward the bottom.

The mid to distal LAD and diagonal branches are typically overlapped.

• Annotated anatomy

<aside> ⭐

This angle is best for visualizing the LM, LCx and branch vessels, and often the proximal LAD.

</aside>

• Examples

AP caudal

The base will be to the left of the screen and the apex to the right. The anterior heart is toward the top of the screen, and the inferior heart is toward the bottom.

The mid to distal LAD and distal LCx are typically overlapped (with themselves, not with one another).

• Annotated anatomy

<aside> ⭐

This angle is best for visualizing the proximal major vessels (LM, LAD, LCx). As compared to LAO caudal, you often get better proximal LAD visualization at the expense of LCx branch vessels.

</aside>