Cath Lab Projection Trainer© Prabhu Sasankan, MD · Cardiology, Weill Cornell Medicine
steep compound angle
RAO/LAO RAO 20 CRA/CAU CRA 32

Occlusion

At risk
LAD
LCx
RCA
CORONARY PROJECTIONS

Left system

Right system

Inspect an artery

FORESHORTENED0%
BEST PROJECTIONRAO 60 / CRA 1 · 0%
Closest standard shot: RAO cranial (0% foreshortened). This is a pure geometry read — it ignores vessel overlap, spine and diaphragm, which is why the real answer is usually a compromise.

Coronary dominance

Display

Anatomy IN PATIENT COORDINATES
LEFT
RIGHT
Drag to move the gantry · scroll to zoom
room
RAO CRANIAL
Best ostial/prox LAD, mid LAD, LM, distal LAD, D1
Foreshortened mid LCx 87%

Inject

22%

Gantry

Rotation RAO 20
Angulation CRA 32

Display

Tissue 100%
Playback 1.0×

Reference angiograms

The supplied figures are the visual reference. These are different patient anatomies; the model reproduces projection relationships, not a pixel match to an individual angiogram.

Figure 21.10: left coronary angiograms in LAO and RAO cranial and caudal projections
Figure 21.11: right coronary LAO, RAO, and LAO cranial projections
Figure 21.7: right, left and balanced coronary dominance

Model & sources

An atlas-based educational reconstruction. The chamber and thoracic surfaces are anatomical meshes; the coronary tree is reconstructed from atlas centerlines with illustrative distal branches and anatomical variants. It is not a patient-specific angiogram or a clinically validated simulator.

The heart retains its position within the thorax. Both panels use one 3D coronary tree. Angiograms use a divergent beam with a 78 cm source–isocenter distance and 104 cm source–detector distance. LAO/RAO and cranial/caudal are defined by detector position; screen orientation is fixed to the patient axis.

LAO caudal: assess separation at the distal left-main bifurcation. The ostial LM and more distal LAD may still be foreshortened. The best angle varies by anatomy.

The diaphragmatic background uses one broad illustrative 3D dome in patient coordinates, projected with the coronary tree. The contour may partly leave the field in tightly collimated or steeply angled views. The radiographic background control includes the diaphragm and skeleton.

Occlusion mode

Territory. The myocardium at risk is the set of segments supplied by every vessel downstream of the chosen lesion in the current coronary tree, so dominance and the ramus variant change it. Segment supply follows the AHA 17-segment convention. Real patients vary, most of all at the apex and in the inferolateral wall.

ECG. The ST shift in each lead is the solid angle that the injured surface subtends at that electrode, computed on the atlas heart with electrodes placed on the atlas thorax. Total occlusion uses the epicardial surface of the territory; subtotal occlusion uses the endocardial surface, blended with a diffuse subendocardial pattern because ST depression does not localize reliably. Limb leads use distant electrodes and Wilson's central terminal. Amplitudes are scaled to typical values, and the QRS, T-wave and Q-wave changes at each stage are illustrative rather than measured.

Echo. Each view is a plane cut through the same atlas meshes that the 3D panel shows, and the fan in the 3D panel carries the live image. Wall motion is an illustrative inward and longitudinal displacement of each vertex, reduced (or reversed, for dyskinesis) in the segments at risk; an old infarct is drawn thinner and brighter. The planes are defined from the LV long axis. In this atlas heart the long axis points steeply anterior, so a true short-axis plane cannot reach the left parasternal skin; the probe is drawn on the beam line just outside the heart rather than at a textbook window.

Criteria and names. ST shifts are measured at the J point. Lead labels, findings and the 3D lead colors use the Fourth Universal Definition cut-points: ST elevation of 2 mm or more in V2–V3 (the cut-point for men aged 40 or older; 2.5 mm in men under 40 and 1.5 mm in women), 1 mm or more in other leads, 0.5 mm or more in V7–V9 and V4R, in two contiguous leads; ST depression of 0.5 mm or more. Pathological Q waves follow the same definition: any Q of 20 ms or more, or QS, in V2–V3; a Q of 30 ms and 1 mm or more, or QS, in two contiguous leads of I and aVL, II, III and aVF, or V4–V6; and, as the posterior equivalent, an R wave of 40 ms or more in V1–V2 with R/S ≥1 and a concordant upright T wave, without a conduction defect. A QS complex in V1 alone is normal. Infarct names (anterior, inferoposterior and so on) are built from the walls that the lesion places at risk. The universal definition and the AHA segment model call the "posterior" wall the inferobasal or inferolateral wall; the app keeps "posterior" because it remains the common clinical name. Some teaching material uses a Q of 40 ms or more than 25% of the R wave; that older rule is stricter than the universal definition.