ARRT Cardiac-Interventional Radiography cheat sheet

Coronary origins: left main arises from the left posterior aortic sinus and divides into LAD and LCx; the RCA arises from the right anterior sinus.

LAD supplies the anterior LV wall, the anterior two-thirds of the interventricular septum, and the apex; LCx supplies the lateral and posterolateral LV.

RCA supplies the right ventricle and inferior LV wall and gives rise to the SA node branch in about 60% and the AV node branch in about 90% of individuals.

Dominance is defined by the artery supplying the posterior descending artery: right dominant ~85%, left dominant ~8%, codominant ~7%.

Cardiac output = heart rate × stroke volume (normal 4–8 L/min); cardiac index = CO/BSA (normal 2.5–4.0 L/min/m²).

Ejection fraction = (EDV − ESV)/EDV; normal 55–70%, reduced systolic function below 40%.

Left coronary flow occurs predominantly in diastole, so tachycardia shortens diastolic perfusion time and worsens subendocardial ischemia.

Normal valve areas: aortic 3–4 cm², mitral 4–6 cm²; severe aortic stenosis is defined by area <1.0 cm², mean gradient ≥40 mmHg, or peak velocity ≥4 m/s.

French sizing: 1 Fr = 1/3 mm; diagnostic coronary catheters are typically 4–6 Fr and guide catheters 5–8 Fr.

Catheter selection: Judkins left and Judkins right curves engage coronary ostia in a normal aorta; Amplatz curves are used for dilated or tortuous ascending aortas.

Angiographic significance: ≥70% diameter stenosis in a major epicardial artery, or ≥50% in the left main, is generally considered flow-limiting.

FFR ≤0.80 across a stenosis indicates hemodynamic significance and benefit from revascularization; FFR >0.80 supports deferring intervention.

ACT targets with unfractionated heparin: 250–300 seconds for PCI, or 200–250 seconds when a glycoprotein IIb/IIIa inhibitor is used.

TIMI flow: 0 = no flow, 1 = faint penetration, 2 = partial filling, 3 = normal brisk flow; TIMI 3 is the post-PCI goal.

PCI technique: balloon inflation typically 8–14 atm; stenting followed by post-dilation for malapposition; drug-eluting stents reduce restenosis versus bare metal.

Transradial access reduces access-site bleeding and permits early ambulation; radial spasm is mitigated with intra-arterial vasodilators.

Cineangiography is typically acquired at 15 frames per second, with 30 fps used for rapid motion; pulsed fluoroscopy is usually 7.5–15 frames per second.

Viewing rules: LAO cranial shows the LAD and diagonals; LAO caudal (spider) shows the left main bifurcation; RAO caudal shows the LCx.

Foreshortening is minimized when the vessel segment lies perpendicular to the central ray; a stenotic segment should be imaged in at least two orthogonal projections.

Magnification increases spatial resolution but raises patient dose roughly in proportion to the square of the magnification factor.

Pixel size = field-of-view width ÷ matrix width; a 20 cm FOV with a 1024 matrix yields pixels of about 0.2 mm.

Quantum mottle is noise from too few photons reaching the detector; it increases with low dose and large patient thickness and is reduced by higher detector dose.

Roadmap imaging subtracts a stored mask from contrast-enhanced frames; patient or table motion causes misregistration artifact.

Last image hold retains the final fluoroscopic frame after exposure ends, allowing review without additional radiation.

Occupational annual dose limits: 50 mSv whole body, 150 mSv lens of the eye, 500 mSv extremities and skin; ALARA requires operating far below these limits.

Inverse square law: scatter dose falls with the square of distance from the patient; doubling distance reduces dose to one quarter.

Typical effective dose: diagnostic coronary angiography ~3–10 mSv; complex PCI can exceed 15 mSv.

Protective shielding: 0.5 mm lead equivalent attenuates roughly 90–95% of scattered photons at fluoroscopic energies.

Dose-reduction decision rules: use pulsed fluoroscopy, tight collimation, last image hold, avoid magnification, and keep the detector as close to the patient as practical.

Skin injury thresholds: transient erythema at about 2 Gy absorbed skin dose; epilation at about 3–5 Gy; monitor cumulative dose in prolonged procedures.

Contrast premedication for prior reaction: prednisone 50 mg orally at 13, 7, and 1 hour before the procedure plus diphenhydramine 50 mg.

Declared pregnant radiation worker: conceptus dose limit of 0.5 mSv per month and 5 mSv total for the gestation (NCRP).