Equipment, Instrumentation, and Safety
Core concepts
This domain covers the tools and safety systems of the cath lab: catheters, guidewires, sheaths, manifolds, transducers, and radiation and electrical safety.
Know catheter characteristics: French size denotes outer diameter (1 Fr ≈ 0.33 mm); larger French means larger bore. Catheter curves are chosen for engaging specific coronaries (e.g., Judkins left and right, Amplatz). Guidewires have a core, tip, and coating; hydrophilic wires track in tortuous vessels, while stiffer wires support device delivery. Sheaths protect the vessel and allow catheter exchange.
Understand the pressure transducer system: leveling at the phlebostatic axis, zeroing to atmosphere, and the square-wave test to check damping. Overdamping underestimates systolic and overestimates diastolic pressure; underdamping exaggerates systolic peaks. Recognize artifacts from air bubbles, kinks, and catheter whip.
Safety includes radiation protection (aprons, thyroid shields, dosimeters), electrical safety (grounding, avoiding wet floors), and infection control. Know emergency equipment: defibrillator, suction, oxygen, and code cart. Contrast reaction management and extravasation recognition are also tested.
Traps
Questions confuse over- and underdamping effects, or mix up French sizing. Remember to level the transducer at the phlebostatic axis, not the patient's shoulder. Do not assume a larger French catheter is more flexible.
Rule of thumb
Square-wave test: a crisp square wave means properly damped; a rounded wave means overdamped (underreads systolic); ringing means underdamped (overreads systolic). Level at the phlebostatic axis and zero to atmosphere.