RCES flashcards

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

Resting membrane potential

Ventricular myocyte resting potential is about -85 to -90 mV, maintained mainly by inward-rectifier K+ conductance and the Na+/K+ ATPase.

Phase 0 depolarization

In atrial and ventricular myocytes and Purkinje fibers, phase 0 is driven by rapid Na+ influx through voltage-gated channels; in the AV node it is Ca2+ dependent.

AV nodal conduction delay

The AV node conducts slowly and decrementally, producing a normal AH interval of 50-120 ms; this delay allows atrial filling before ventricular systole.

Effective refractory period

ERP is the longest coupling interval that fails to propagate; it is shortest in atrial tissue, longer in the AV node, and roughly 200-250 ms in ventricular myocardium.

Coronary sinus anatomy

The coronary sinus drains most of the left ventricle, runs in the left AV groove, and enters the right atrium near the tricuspid annulus; its ostium guides LV mapping.

Bipolar electrogram filtering

Intracardiac bipolar signals are usually bandpass filtered at 30-500 Hz, reducing baseline wander and high-frequency noise while preserving local activation timing.

Ablation impedance rise

During RF ablation, impedance typically ranges about 80-150 ohms; an abrupt rise suggests coagulum or tissue desiccation, while an abrupt fall suggests steam pop or dislodgment.

RF lesion determinants

Radiofrequency lesion size depends on power, duration, electrode-tip size, contact force, irrigation, and tissue contact; standard 4-mm-tip lesions are roughly 3-6 mm deep.

50/60 Hz notch filter

The notch filter removes powerline interference at 50 or 60 Hz without affecting most electrogram frequencies, but it can distort signals near that frequency.

Normal AH interval

The AH interval, measured from the atrial electrogram to the His deflection on a His-bundle recording, is normally 50-120 ms and reflects AV nodal conduction time.

Normal HV interval

The HV interval, measured from the earliest His deflection to the earliest ventricular activation, is normally 35-55 ms and reflects His-Purkinje conduction.

Corrected sinus node recovery time

cSNRT equals the maximum post-pacing pause minus the baseline sinus cycle length; a normal value is generally less than 550 ms, indicating normal sinus node automaticity.

Concentric retrograde activation

During ventricular pacing, concentric retrograde atrial activation (His then CS ostium then proximal to distal CS) suggests conduction over the AV node rather than an accessory pathway.

Entrainment PPI-TCL

The postpacing interval minus tachycardia cycle length estimates distance from the pacing site to the reentry circuit; a difference under about 20-30 ms suggests the site is within the circuit.

Cavotricuspid isthmus ablation

CTI ablation for typical atrial flutter creates a line between the tricuspid annulus and inferior vena cava; bidirectional conduction block is the acute endpoint.

Pulmonary vein isolation endpoint

PVI requires electrical isolation of each pulmonary vein, demonstrated by entry block, exit block, and absence of PV potentials; circumferential antral lesions are standard.

Cryoablation temperatures

Cryomapping near -30°C is reversible and used to test safety; therapeutic cryoablation typically targets -50 to -70°C to create durable tissue injury.

AVNRT slow pathway target

Slow pathway modification for AVNRT targets the inferior triangle of Koch near the coronary sinus ostium; success is lack of inducible AVNRT with low heart-block risk.

Phrenic nerve injury risk

Right phrenic nerve injury can occur during right pulmonary vein or SVC ablation; pacing the phrenic nerve and monitoring diaphragm movement helps detect impending injury.

NBG pacemaker code

The NBG code describes paced chamber, sensed chamber, response to sensing, rate modulation, and multisite pacing; examples include VVI, DDD, and DDDR.

Mode switch

In DDD pacemakers, mode switch changes to a non-tracking mode such as DDIR or VVIR during atrial tachycardia or fibrillation to avoid rapid ventricular pacing.

ICD ATP therapy

Antitachycardia pacing delivers rapid ventricular bursts to terminate organized VT; it is painless and often programmed before shocks for fast VT.

CRT indication

Cardiac resynchronization therapy is indicated for selected heart failure patients with reduced ejection fraction and wide QRS, especially LBBB with QRS 150 ms or greater.

Magnet over ICD

Placing a magnet over an ICD usually suspends tachyarrhythmia detection and therapy without affecting bradycardia pacing; removal restores programmed detection.

Midazolam reversal

Flumazenil reverses benzodiazepine sedation such as midazolam; it can precipitate seizures in chronic benzodiazepine users and is given in small titrated doses.

Fentanyl reversal

Naloxone reverses opioid effects such as fentanyl-induced respiratory depression; repeated doses may be needed because naloxone's duration is shorter than many opioids.

Adenosine half-life

Adenosine has a half-life under 10 seconds and causes transient AV block; it can precipitate bronchospasm and should be used cautiously in asthma.

Lidocaine maximum dose

Lidocaine without epinephrine is limited to about 4.5 mg/kg; with epinephrine the limit is about 7 mg/kg; toxicity includes seizures and cardiac depression.

Procedure time-out

A time-out immediately before the procedure verifies patient identity, procedure, site, consent, allergies, implants, and equipment availability with the whole team.

ALARA radiation principle

ALARA means keeping radiation dose as low as reasonably achievable by minimizing fluoroscopy time, using pulsed fluoroscopy, collimation, and inverse-square distance.

Heparin ACT target

For left atrial ablation, unfractionated heparin is titrated to an activated clotting time of about 300-350 seconds to reduce thromboembolism during catheter manipulation.

SBAR handoff

SBAR structures handoff communication as Situation, Background, Assessment, and Recommendation; it improves transfer of pertinent periprocedural information between teams.