CCT (ASQ) cheat sheet

Normal conduction sequence: SA node → AV node → bundle of His → right and left bundle branches → Purkinje fibers.

SA node intrinsic firing rate is 60–100 bpm; AV node 40–60 bpm; Purkinje/ventricular pacemakers 20–40 bpm.

Cardiac output = heart rate × stroke volume; normal resting CO is approximately 4–8 L/min.

Frank-Starling relationship: increased ventricular filling (preload) raises stroke volume up to a physiologic limit.

Coronary arteries arise from the aortic root: left main divides into LAD and circumflex; right coronary supplies the AV node in most people.

The left ventricle has the thickest myocardium because it pumps against systemic vascular resistance; right ventricle pumps to the low-pressure pulmonary circuit.

Chordae tendineae and papillary muscles prevent AV valve prolapse during ventricular systole; semilunar valves have no chordal support.

Systemic circulation order: left atrium → mitral valve → left ventricle → aortic valve → aorta → body → vena cavae → right atrium.

Standard paper speed is 25 mm/s; one small box = 0.04 s, one large box = 0.20 s, 300 large boxes = 1 minute.

Heart rate estimate: 300 ÷ number of large boxes between R waves, or count R waves in a 6-second strip × 10.

Normal sinus rhythm: upright P in lead II, one P per QRS, PR 0.12–0.20 s, QRS < 0.12 s, rate 60–100 bpm.

Sinus bradycardia < 60 bpm; sinus tachycardia > 100 bpm; both retain normal P-QRS relationship.

Atrial fibrillation: irregularly irregular rhythm with absent discrete P waves and fibrillatory baseline.

Ventricular tachycardia: wide QRS (> 0.12 s), rate typically > 100 bpm, no consistent P-QRS association.

Ventricular fibrillation: chaotic, irregular, wide undulating waveform with no identifiable QRS complexes; pulseless.

First-degree AV block: PR > 0.20 s with every P conducted; Mobitz I shows progressive PR lengthening; Mobitz II shows constant PR with dropped beats.

Asystole appears as a flat line; confirm in more than one lead and check leads/connections before treating.

12-lead ECG electrode placement: limb leads on arms and legs; V1 4th intercostal space right sternal border, V2 4th ICS left sternal border, V4 5th ICS midclavicular, V3 midway between V2 and V4.

Exercise stress testing is interpreted against target heart rate, commonly 85% of age-predicted maximum (220 − age).

Holter monitor records 24–48 hours of continuous ECG; event monitors are used for infrequent symptoms over longer periods.

Echocardiography assesses wall motion, valve function, and ejection fraction; normal EF is approximately 55–70%.

Cardiac catheterization measures pressures and coronary anatomy; the left heart is accessed retrograde via the aorta.

Troponin and CK-MB are cardiac biomarkers; troponin rises within hours of myocardial injury and remains elevated for days.

BNP is released by stretched ventricular myocardium and supports diagnosis of heart failure.

Tilt-table testing provokes neurally mediated syncope by positional change under continuous monitoring.

Defibrillation for VF/pulseless VT: biphasic 120–200 J (manufacturer range) or monophasic 360 J, with immediate CPR resumption after shock.

Synchronized cardioversion delivers shock on the R wave to avoid inducing VF; used for unstable tachycardias with a pulse.

Standard electrode placement for defibrillation is right infraclavicular (sternum) and left lateral (apical) positions.

Universal precautions: gloves for all contact with blood or body fluids; hand hygiene before and after patient contact.

Before any shock, announce 'clear,' visually confirm no one is touching the patient or bed, and confirm oxygen is directed away.

Continuous SpO2 and ECG monitoring during sedation or stress testing; report new dysrhythmia or desaturation promptly.

Document rhythm, energy delivered, number of shocks, and patient response for every emergency event.

Fall and skin safety: inspect electrode sites for irritation, rotate sites, and secure cables to prevent traction injury.

ECG machine calibration standard: 1 mV input produces a 10 mm deflection at 25 mm/s paper speed.

Common artifacts: baseline wander from movement or respiration, 60-Hz interference from electrical sources, and muscle tremor from shivering.

Loose or dried electrodes raise skin impedance and increase artifact; clip hair and abrade skin rather than shaving if possible.

Lead reversal signs: reversed arm leads invert lead I; precordial misplacement distorts R-wave progression across V1–V6.

Defibrillator checks include battery charge, self-test, cable and paddle condition, and documented energy output verification.

Daily equipment checks should confirm monitor alarms are enabled and audible, with appropriate rate and SpO2 limits.

Store electrodes sealed and within expiration; dried gel degrades signal quality and adhesion.

Holter and event recorder quality control includes verifying clock time, battery status, and complete lead attachment before discharge.