CIRCC cheat sheet

Mean arterial pressure = (systolic + 2 × diastolic) / 3; a MAP ≥ 65 mmHg is the usual target for organ perfusion.

Fluid-filled catheter systems underdamp when air or compliance is present and overdamp when bubbles, kinks, or clot narrow the tubing; both distort the waveform.

Natural frequency and damping coefficient determine fidelity: optimal damping ratio is about 0.6–0.7 for accurate systolic and diastolic reproduction.

Fick principle: cardiac output = oxygen consumption / (arterial O2 content − mixed venous O2 content), with content in mL O2 per dL.

Thermodilution cardiac output uses the Stewart-Hamilton equation; injectate volume and temperature must be entered exactly or output is miscalculated.

Transducer zeroing is referenced to the phlebostatic axis (fourth intercostal space, midaxillary line); leveling errors of 2.5 cm shift readings roughly 2 mmHg.

Radiation dose is reduced by maximizing distance from the source, minimizing fluoroscopy time, and using pulsed or low-dose fluoroscopy modes.

Coronary flow reserve is the ratio of hyperemic to resting flow; a value below about 2.0 suggests functionally significant epicardial stenosis or microvascular disease.

Coronary arteries arise from the aortic sinuses: left main divides into LAD and circumflex; right coronary artery supplies the SA node in about 60% of people.

The LAD supplies the anterior wall and anterior two-thirds of the septum; the circumflex supplies the lateral wall; the RCA supplies the inferior wall and right ventricle.

Normal left ventricular ejection fraction is 55–70%; values below 40% indicate reduced systolic function and elevated procedural risk.

Cardiac output = heart rate × stroke volume; stroke volume depends on preload, afterload, and contractility.

The Frank-Starling relationship states that increasing end-diastolic volume increases stroke volume up to a point of overstretch.

Aortic stenosis severity: mean gradient ≥ 40 mmHg, peak velocity ≥ 4.0 m/s, or valve area < 1.0 cm² indicates severe disease.

Mitral stenosis is defined by valve area < 1.5 cm²; the normal mitral valve area is 4–6 cm².

Right heart pressures: normal right atrial pressure 2–6 mmHg, right ventricular systolic 15–30 mmHg, pulmonary artery systolic 15–30 mmHg.

Diagnostic catheter sizes: 4F–6F are typical for coronary angiography; larger French sizes accommodate higher flow and complex intervention.

French size equals diameter in millimeters multiplied by 3; a 6F sheath has an outer diameter of about 2 mm.

Guide catheter selection: Judkins Left for left coronary, Judkins Right for right coronary; Amplatz curves aid in anomalous or tortuous anatomy.

ACT target during PCI with heparin is typically 250–350 seconds; protamine reverses heparin if bleeding occurs.

Balloon angioplasty sizing follows a balloon-to-artery ratio near 1.0; stent deployment uses high-pressure post-dilation to optimize apposition.

Fractional flow reserve ≤ 0.80 indicates a hemodynamically significant lesion warranting revascularization.

Transseptal puncture crosses the fossa ovalis from right to left atrium, guided by fluoroscopy and often TEE or intracardiac echo.

Pericardiocentesis is performed with a subxiphoid approach under fluoroscopic or echocardiographic guidance; the needle is directed toward the left shoulder.

Informed consent must document risks including bleeding, infection, stroke, MI, arrhythmia, and contrast nephropathy before the procedure.

Contrast-induced nephropathy risk rises with baseline creatinine; hydration with isotonic saline and minimizing contrast volume are standard preventive measures.

Metformin is typically held around procedures involving iodinated contrast in patients with renal impairment per institutional protocol.

Radiation safety: use lead aprons of at least 0.5 mm lead equivalent, thyroid shields, and dosimeters; ALARA principle governs exposure.

Universal protocol requires verifying patient identity, procedure site, and consent before starting any invasive procedure.

ACT and coagulation status are checked before sheath removal; manual compression or closure devices are used per hemostasis protocol.

Anaphylactoid reactions to contrast are managed with antihistamines, steroids, and epinephrine for severe reactions; airway and hemodynamic support are priorities.

Post-procedure monitoring includes access-site assessment for hematoma or pseudoaneurysm, distal pulse checks, and vital sign surveillance.