CRAS flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

SA node firing rate

The sinoatrial node normally depolarizes at 60-100 beats per minute and serves as the dominant cardiac pacemaker because it has the fastest intrinsic automaticity.

Cardiac output formula

Cardiac output equals heart rate multiplied by stroke volume. Stroke volume is determined by preload, afterload, and myocardial contractility.

AV node conduction delay

The atrioventricular node conducts slowly, creating a physiologic delay that lets the ventricles fill before they contract.

Phase 4 depolarization

Spontaneous depolarization during phase 4 determines automaticity; a steeper slope raises the firing rate of pacemaker cells.

Reentry mechanism

Reentry requires a circuit, unidirectional block, and slowed conduction. It underlies most paroxysmal supraventricular tachycardias and atrial flutter.

Delayed afterdepolarization

A triggered beat arising from calcium overload during phase 4, classically caused by digoxin toxicity and treated by correcting the underlying cause.

ECG paper calibration

At standard speed of 25 mm/s, one small box equals 0.04 second and one large box equals 0.20 second.

Atrial fibrillation ECG

Atrial fibrillation shows irregularly irregular RR intervals, absent discrete P waves, and a fibrillatory baseline.

Ventricular tachycardia criteria

A wide-complex tachycardia with QRS over 0.12 second and rate above 100 bpm; AV dissociation and capture beats support ventricular origin.

Third-degree AV block

Complete AV block shows no relationship between P waves and QRS complexes, with an escape rhythm maintaining ventricular rate.

Holter monitor indication

A 24- to 48-hour continuous recording is used when arrhythmia symptoms occur at least daily.

Implantable loop recorder

A subcutaneous device providing continuous rhythm monitoring for up to 2-3 years, used for infrequent unexplained syncope.

Tilt-table testing

A test used to evaluate suspected vasovagal syncope when history, examination, and ECG are nondiagnostic.

Vaughan-Williams classification

A drug classification: class I sodium-channel blockers, class II beta-blockers, class III potassium-channel blockers, class IV calcium-channel blockers.

Class IC contraindication

Flecainide and propafenone are avoided in structural heart disease or reduced ejection fraction because of proarrhythmia risk.

Adenosine action

Adenosine transiently blocks AV nodal conduction and terminates AV nodal reentrant tachycardia; its half-life is under 10 seconds.

Amiodarone toxicity monitoring

Amiodarone requires periodic monitoring for thyroid, pulmonary, hepatic, corneal, and neurologic adverse effects.

NBG pacemaker code

Five positions describe chamber paced, chamber sensed, response to sensing, rate modulation, and multisite pacing.

Failure to capture

A pacing spike appears without a resulting P wave or QRS complex, indicating the stimulus did not depolarize myocardium.

ICD therapy modes

Implantable defibrillators terminate ventricular tachycardia or fibrillation with antitachycardia pacing or shocks and also provide bradycardia pacing.

Pacemaker magnet response

Magnet application typically converts a pacemaker to asynchronous pacing and suspends tachytherapy in an implantable defibrillator.

Electrophysiology study catheters

Multipolar catheters placed in the high right atrium, His bundle region, coronary sinus, and right ventricle map activation and conduction intervals.

Cavotricuspid isthmus ablation

Ablation of the cavotricuspid isthmus treats typical atrial flutter, with bidirectional conduction block as the endpoint.

Pulmonary vein isolation

Ablation encircling the pulmonary vein ostia is the cornerstone of atrial fibrillation ablation, aiming to eliminate vein triggers.

Ablation complication: tamponade

Cardiac perforation during ablation can cause pericardial effusion and tamponade, presenting with hypotension and elevated filling pressures.

ICD shock education

Patients are taught that a shock with symptoms such as syncope or chest pain requires immediate emergency evaluation.

Device interrogation checks

Follow-up interrogation assesses battery status, lead impedance, sensing, and capture thresholds to detect malfunction early.

Anticoagulation teaching

Patients on anticoagulants for atrial fibrillation learn bleeding signs, adherence, and drug or dietary interactions.

Defibrillation safety

Before defibrillation, clear all personnel, remove oxygen sources, ensure dry skin, and verify correct pad placement.

Radiation safety triad

Occupational radiation exposure is minimized by time, distance, and shielding; dosimeters track cumulative dose.

SBAR handoff

A structured communication format covering situation, background, assessment, and recommendation to reduce omission of critical information.

Scope of practice

Defines tasks a monitor technician or nurse may perform; arrhythmia interpretation requires documented training and competency validation.