NOVA- Anesthesia ECG Quiz 5

Normal P waves

Origin in atria at or near the sinus node

Abnormal P wave

Atrial origin other than sinus node or retrograde activation from AV node

No P waves

Origin below atria, ectopic rhythm

Narrow QRS

Ventricular depolarization is following normal conduction path- efficient/ fast conduction

Wide QRS

Ventricular depolarization is initiated within ventricular myocardium- slow conduction

Sinus/ atrial origin

1:1 P:QRS

AV dissociation

Not 1:1 P:QRS

Types of nonsinus arrhythmias: ectopic rhythms

-junctional rhythm

-idioventricular rhythm

Ectopic rhythms

-nonsinus arrhythmias

-refers to originating outside of sinus node

-can be a single beat or a sustained beat

-caused by enhanced automaticity of a non-sinus node pacemaker site

-disorder or impulse formation

-digitalis toxicity, caffeine, alcohol, stimulants, and psychological stress

Junctional rhythm

-absence of P waves or possibly retrograde P waves

-narrow QRS

-40-60bpm (AV NODE ORIGIN)

Accelerated Junctional Rhythm

-regular

-rate: 100-150bpm

-P Wave: NONE or INVERTED

-PR Interval: None or <0.12

-QRS: <0.12 sec

Idioventricular rhythm

-absence of P waves

-wide QRS

-rate <40bpm (ventricular origin)

-regular

Accelerated idioventricular rhythm

-p waves absent

-wide QRS

-P:QRS n/a

-regular

-rate: 75-100pm

-origin: ventricular foci, accelerated and over-driving other pacemakers

-seen during acute MI or during early hours of reperfusion (favorable sign that occluded coronary artery has been successfully reopened)

Reentrant rhythms

Abnormal rhythms due to the creation of a reentry loop

-most commonly caused by a combination of adjacent tissue heterogeneity and premature beat

-continues for as long as depolarization wavefront encounters excitable tissue

-disorder of impulse transmission

Types of nonsinus arrhythmias: reentrant rhythms

-premature atrial contraction (PAT)

-junctional premature beat (PJC)

Premature atrial contraction (PAC)

-common benign phenomena

-can initiate sustained arrhythmias

-originates in the atrium, NOT SA NODE

-distinguished by contour of P wave and timing (happens earlier than next anticipated sinus wave)

-normal QRS

Junctional premature beat (PJC)

-common benign phenomena

-originates in the AV node

-absent or retrograde P wave

-normal QRS

-happens early

Types of sustained supraventricular arrhythmias

-AV nodal reentry tachycardia (AVNRT)

-atrial fibrilation

-atrial flutter

-multifocal atrial tachycardia (MAT)

-paroxysmal atrial tachycardia (PAT)

AV node reentry tachycardia (AVNRT)

-P waves buried within QRS

-pseudo R' seen in V1

-narrow QRS

-1:1 P:QRS

-Regular rhythm

-150-250bmp

-Origin: AV node reentry loop

-common arrhythmia, usually initiated by premature supraventricular beat, sudden onset/ termination

Treatment for AV node reentry tachycardia (AVNRT)

-vagal maneuvers (slows conduction through AV node)

-adenosine 6mg, second dose 12mg (blocks AV node)

-synchronized cardioversion 50-100J

Carotid massage

-common vagal maneuver

-check for carotid bruits or history for known carotid artery disease

-lay pt supine, extend neck and rotate head away

-palpate carotid artery at angle of jaw, apply pressure for 10-15s

Atrial flutter

-P waves- characteristic "sawtooth" pattern or flutter waves (F waves) (most prominent in leads II and III

-Narrow QRS

-Multiple Ps: 1 QRS

-depends on degree of AV block

-regular rhythm

-250-350bpm for atrial rate, ventricular rate is 1/2, 1/3, or 1/4

-origin most commonly, single reentry circuit along annulus of tricuspid valve

-uncommon arrhythmia

Atrial flutter AV block

-AV node cannot handle the extraordinary number of atrial impulses

-2:1 block most common

-carotid massage might increase the degree of the block (does not terminate rhythm)

Atrial fibrillation

-P waves absent

-narrow QRS

-P:QRS unrelated/ variable

-irregularly irregular

-chaotic atrial activity 500 bpm (loss of atrial kick)

-origin: multiple tiny reentrant circuits in atria

-most common sustained arrhythmia

Atrial fibrillation

-risk factors: elderly, OSA, HTN, obesity, and alcoholism

-symptoms: angina, SOB, dizziness

-treatment:

-rate control: B blockers or Ca channel blockers in addition to an anticoagulant

-rhythm control: antiarrhythmic meds, catheter ablation, cardioversion

Multifocal atrial tachycardia (MAT)

-P waves present (varying morphology)

-need > 3 different P wave morphology to diagnose

-narrow QRS

-1:1 P:QRS

-varying irregular PR intervals

-rate: 100-200bpm

-<100bpm- wandering pacemaker

-origin: multiple sites in atria

-common in pts with severe lung disease

Paroxysmal atrial tachycardia (PAT)

-P waves normal

-narrow QRS

-1:1 P:QRS

-regular rhythm (warm up and cool down periods)

-rate: 100-200 bpm

-origin: enhanced automaticity of ectopic focus in atria

-caused by healthy hearts and digitalis toxicity

-CAROTID MASSAGE HAS NO EFFECT

Types of ventricular arrhythmias

-premature ventricular contractions (PVCs)

-ventricular tachycardia

-ventricular fibrillation

-accelerated idioventricular rhythm

-torsades de pointes

Premature ventricular contractions (PVCs)

-most common ventricular arrhythmia

-typically occur randomly

-origin: ventricular myocardium

-wide abnormal QRS (>0.12s)

-no P waves, sometimes retrograde

-usually followed by prolonged compensatory pause before next beat (>3 is considered VT)

Bigeminy

Alternating normal and PVC

Trigeminy

PVC occurs every THIRD beat

Rules of malignancy

-frequent PVCs

-runs of consecutive PVCs

-multiform PVCs

-R on T- PVCs falling on T wave, a vulnerable period in cardiac cycle, my percipitate VT

-PVCs during an acute MI

Ventricular tachycardia

-P wave absent

-wide QRS

-P:QRS n/a

-regular rhythm

-rate: 120-200bpm

-origin: ventricles

-scarred myocardium provides reentrant track (NO RESPONSE ON CAROTID MASSAGE)

CO and coronary perfusion

Sustained VT severely compromises what two things?

Treatment for VT

Acute-

ACLS with pulse (amiodarone, lidocaine, and procainamide)

ACLS without pulse (defibrillation and CPR)

Chronic-

Antiarrhythmic drugs and catheter ablation

Ventricular fibrillation (VF)

-p waves absent

-QRS absent

-P:QRS n/a

-spasmodic (coarse) or gentle undulation (fine) of ECG tracing

-seen almost solely in dying hearts

-most frequently encountered arrhythmia in sudden death

-often preceded by VT

-need immediate CPR and defibrillation

Torsade de Pointes

-twisting of the points

-outline looks like a party streamer

-P wave absent

-wide and polymorphic QRS

-associated with prolonged QT interval (QTc is associated with prolonged ventricular repolarization)

-caused by HypoCa2+, HypoMg2+, and HypoK+

-PVC falling during the QTI initiates this

-long QT syndrome

-treatment: magnesium

Supraventricular

Which arrhythmias are associated with a narrow QRS complex?

-may terminate with carotid massage

-cannon A and fusion beats are not seen

Ventricular

Which arrhythmias are associated with a wide QRS complex?

-no response to carotid massage

-may see cannon A waves and fusion beats

Bundle branch block and aberrant conduction

What two cases cause supraventricular origin arrhythmias to result in a wide QRS? These may terminate with carotid massage.

Cannon A waves

Seen in ventricular tachycardia

-occurs when atria contract against closed mitral/ tricuspid valves

Fusion beats

Seen in ventricular tachycardia

-atrial depolarization slips through AV node, results in QRS morphology that looks part supraventricular/ ventricular