PANCE Blueprint Cardiology (13%)

Conduction Disorders (PEARLS)

The NCCPA™ PANCE Cardiology System Content Blueprint covers 10 different conduction disorders


Conduction Quick Cram
Normal sinus rhythm Regular rhythm of the heart cycle stimulated by the SA node with an average heart rate of 60-100 bpm
Sinus tachycardia Sinus rhythm but with a heart rate over 100 bpm
Sinus bradycardia Sinus rhythm with a resting heart rate of < 60 bpm in adults, or below the normal range for age in children
Atrial fibrillation/flutter Irregularly irregular rhythm with disorganized and irregular atrial activations and an absence of P waves

Regular, sawtooth pattern and narrow QRS complex

Atrioventricular block First Degree AV Block: The PR interval is longer than 0.2 seconds or one block on EKG.

Type I Second Degree (Wenckebach): progressive lengthening of PR interval then missed QRS complex.

Type II Second Degree (Mobitz): fixed PR interval with occasional dropped QRS complexes

Third Degree AV Block: no association between P wave and QRS complex

Bundle branch block Left: R and R’ (upward bunny ears) in V4-V6

Right: R and R’ (upward bunny ears) in V1-V3

Paroxysmal supraventricular tachycardia Narrow complex tachycardia
Premature Beats PVC: Early wide bizarre QRS, no p wave seen

PAC: abnormally shaped P wave

PJC: Narrow QRS complex, no p wave or inverted p wave

Sick sinus syndrome Brady-tachy: Arrhythmia in which bradycardia alternates with tachycardia

Sinus arrest: prolonged absence of sinus node activity (absent P waves) > 3 seconds

Sinus arrhythmia Normal, minimal variations in the SA Node's pacing rate in association with the phases of respiration. Heart rate frequently increases with inspiration, decreases with expiration
Torsades de pointes Polymorphic ventricular tachycardia that appears to be twisting around a baseline
Ventricular fibrillation Erratic ventricular rhythm without identifiable P waves, QRS complexes, or T waves
Ventricular tachycardia Wide complex tachycardia with three or more consecutive ventricular premature beats

Normal Sinus Rhythm

normal-sinus-rythm

Normal sinus rhythm refers to both a normal heart rate and rhythm.

  • Normal heart rates are from 60 to 100 beats per minute.
  • Electrical impulse originates in the sinoatrial node (SA).
  • P waves are upright and appear before each QRS and have the same shape.
  • Intervals between the P waves are regular although some variations can occur with respiration.

Sinus Tachycardia

sinus-tachycardia

Sinus tachycardia is a normal sinus rhythm but with a heart rate over 100 bpm.

  • It is a normal response to exercise, excitement and some illnesses.

Sinus Bradycardia

sinus-bradycardia

Sinus bradycardia is a sinus rhythm with a rate of 40-60 bpm

Atrial fibrillation/flutter

afib

Irritable sites in the atria fire very rapidly, between 400-600 bpm

  • This very rapid pacemaking caused the atria to quiver
  • The ventricles beat at a slower rate due to the AV node is blocking of some of the atrial impulses

Presentation:

  • Elderly, excessive alcohol use
  • Symptoms range from syncope, dyspnea, palpitations to no symptoms
  • Irregularly irregular pulse

EKG: Low-amplitude fibrillatory waves without discrete P waves and an irregularly irregular pattern of QRS complexes

Treatment:

  • Rate: Calcium channel blocker (diltiazem, verapamil) or beta-blocker (metoprolol)
  • Rhythm:
    • Duration <48 hours - cardioversion, amiodarone (obtain echo to determine if a clot is present prior
      to cardioversion)
    • Duration >48 hours - anticoagulation for 21 days prior to cardioversion

Anticoagulation is determined by CHA2DS2-VASc  or CHADS2 scoring to assess the risk of stroke

  • 0 points – no therapy or 81–325 mg/day of aspirin
  • 1 point – either 81–325 mg/day of aspirin or anticoagulation
  • 2 or more points – anticoagulation

Atrial Flutter

atrial-flutter

There are two types of atrial flutter

  • Type I (also called classical or typical) has a rate of 250-350 bpm
  • Type II (also called non-typical) are faster, ranging from 350-450 bpm

EKG: Regular, sawtooth pattern (F-waves), narrow QRS complex

Occasionally occurs in COPD, congestive heart failure, atrial septal defect, coronary artery disease

Similar treatment as atrial fibrillation

Atrioventricular block 

  1. 1st degree: PR interval > .2 seconds
  2. 2nd degree two types:
    1. type 1 – longer, longer, drop now you’ve got a Wenckebach
    2. type 2 – some get dropped some get through now you’ve got Mobitz 2
  3. 3rd degree: P’s and Q’s don’t agree now you’ve got 3rd degree

First degree AV block

First Degree AV BLOCK

PR interval > .2 seconds

First-degree heart block is actually a delay rather than a block. It is caused by a conduction delay at the AV node or bundle of His. This means than the PR Interval will be longer than normal (over 0.20 sec.).

  • (PR interval longer than 1 big box 0.20 seconds)

Second degree AV block Type 1 (Wenckebach) and Type 2 (Mobitz)

Type I: Wenckebach block

second-degree-heart-block-type-i

Wenckebach (longer, longer, longer drop now you've got a Wenckebach)

With second-degree heart block, Type I, some impulses are blocked but not all. More P waves can be observed vs QRS Complexes on a tracing. Each successive impulse undergoes a longer delay. After 3 or 4 beats the next impulse is blocked. On an EKG tracing, PR Intervals will lengthen progressively with each beat until a QRS Complex is missing. After this blocked beat, the cycle of lengthening PR Intervals resumes. This heart block is also called a Wenckebach block.

Type II: Mobitz

second-degree-heart-block-type-ii

MOBITZ 2 (some get dropped some get through now you've got mobitz 2)

With Mobitz Type II blocks, the impulse is blocked in the bundle of His. Every few beats there will be a missing beat but the PR Interval will not lengthen.

Third degree AV block

third degree av block

P’s and Q’s don’t agree now you've got 3rd degree

With this block, no atrial impulses are transmitted to the ventricles.

As a result, the ventricles generate an escape impulse, which is independent of the atrial beat. In most cases the atria will beat at 60-100 bpm while the ventricles asynchronously beat at 30-45 bpm.

  • There is no electrical communication between the atria and the ventricles complete AV dissociation. P wave do not match the QRS one for one

Bundle branch block

bbb

With this conduction block, either the left or right bundle branch is blocked intermittently or fixed.

The QRS complex is wider than normal (> 0.12 sec.).

Using a 12 lead EKG, blocks in either the left or right bundle branch may be diagnosed.

  • QRS complex > .12 seconds
  • May be due to MI
  • Left: R and R’ (upward bunny ears) in V4-V6
  • Right: R and R’ (upward bunny ears) in V1-V3

Paroxysmal supraventricular tachycardia

Summary of supraventricular tachycardia:

Heart rate: 150-250 BPM

Types:

  1. Paroxysmal SVT – no structural abnormalities
  2. AV nodal reentrant tachycardia
  3. Wolff Parkinson White – Bundle of Kent fibers and delta wave on EKG
  4. Multifocal atrial tachycardia: EKG: Irregular tachycardia, narrow QRS complex, abnormally shaped P waves with different morphology

Treatment:

  • Valsalva for stable patients
  • Adenosine for symptomatic patients
  • Definitive treatment: Radiofrequency ablation
  • WPW- do not administer adenosine nor calcium channel blockers

Supraventricular Tachycardia 

svt

A faster than normal heart rate beginning above the heart's two lower chambers in the atria, AV junction or SA node

Wolff-Parkinson-White Syndrome

wolff-parkinson-white-syndrome

This occurs when the impulse travels between the atria and ventricles via an abnormal path, called the bundle of Kent

  • The impulse, not being delayed by the AV node, can cause the ventricles to contract prematurely
  • EKG characteristics include a shorter PR Interval, longer QRS complex and a delta wave (click here)

Multifocal Atrial Tachycardia

multifocal-atrial-tachycardia

When multifocal atrial tachycardia occurs, multiple (non-SA) sites are firing impulses.

  • EKG: Rapid irregular rhythm > 100 bpm. At least 3 distinct P-wave morphologies
  • The PR Interval varies
  • Ventricular rhythm is irregular

Premature Beats

Premature atrial contractions (PAC), Premature junctional complexes (PJC) and premature ventricular contractions(PVC)

  • Typically benign. May cause palpitations.
  • Increased frequency with stimulants (Ie. Caffeine)

EKG: Irregular beats (three types)

  1. PVC – widened QRS
  2. PAC – abnormally shaped P wave
  3. PJC – narrow QRS usually measured at 0.10 sec or less

Every 3rd beat – trigeminy. Every other beat- bigeminy

Treatment: None or beta-blockers if symptomatic

Premature atrial beats

This rhythm strip displays the typical pattern of frequent PACs (arrows) separated by post-extrasystolic pauses

This rhythm strip displays the typical pattern of frequent PACs (arrows) separated by post-extrasystolic pauses

This occurs when an ectopic site within the atria fires an impulse before the next impulse from the SA node

  • EKG: An abnormal (non-sinus) P wave is followed by a QRS complex
    • If the ectopic site is near the SA node, the P wave will likely have a shape similar to a sinus rhythm. But this P wave will occur earlier than expected.

Premature junctional beats

Premature QRS complexes without a preceding P wave. The QRS morphology is very similar to the sinus complexes

Premature QRS complexes without a preceding P wave.
The QRS morphology is very similar to the sinus complexes

Premature junctional complex (PJC) occurs when an irritable site within the AV node fires an impulse before the SA node. This impulse interrupts the sinus rhythm

  • EKG: Narrow QRS complex, either (1) without a preceding P wave or (2) preceded by an abnormal P wave with a PR interval of < 120 ms
  • The QRS complex will be narrow, usually measured at 0.10 sec or less

Premature ventricular contractions

pvc

Premature ventricular complexes (PVCs) occur when a ventricular site generates an impulse. This happens before the next regular sinus beat.

  • EKG: Broad QRS complex (≥ 120 ms) with abnormal morphology.
  • Look for a wide QRS complex, equal or greater than 0.12 sec
  • The QRS complex shape can be bizarre
  • The P wave will be absent

Sick sinus syndrome

sick sinus syndrome

Population: Elderly

A collective term used to describe dysfunction in the sinus node automaticity and impulse generation

  • Sinus bradycardia: Sinus rhythm with a resting heart rate of < 60 bpm in adults, or below the normal range for age in children
  • Sinus pause: pause < 3 seconds
  • Sinus arrest: pause > 3 seconds
  • Tachy-Brady Syndrome: Episodes of alternating sinus tachycardia and bradycardia

Treatment: Pacemaker

Sinus arrhythmia

sinus-arrhythmia

Sinus arrhythmia represents normal, minimal variations in the SA Node pacing rate in association with the phases of respiration.

  • Heart rate frequently increases with inspiration and decreases with expiration

Torsades de pointes

torsade-de-pointes


Torsade de Pointes is a special form of ventricular tachycardia

  • EKG: Polymorphic ventricular tachycardia that appears to be twisting around a baseline
  • Etiology: Hypokalemia or hypomagnesemia
  • Treatment: IV Magnesium sulfate

Ventricular tachycardia

v tach

A sequence of three PVCs in a row is ventricular tachycardia.

  • The rate will be 120-200 bpm.
  • There are several different varieties of VT — the most being Monomorphic VT

Ventricular Tachycardia Monomorphic

ventricular-tachycardia-monomorphic

Monomorphic ventricular tachycardia occurs when the electrical impulse originates in one of the ventricles. The QRS complex is wide. Rate is above 100 bpm.

EKG: Wide complex tachycardia

Treatment:

  • Stable- amiodarone, lidocaine
  • Unstable- CPR and defibrillation

Ventricular Tachycardia Polymorphic

ventricular-tachycardia-polymorphic

Polymorphic ventricular tachycardia has QRS complexes that vary in shape and size. If a polymorphic ventricular tachycardia has a long QT Interval, it could be Torsade de Pointes.

Pacemaker Rhythm

pacemaker-rhythm

Atrial and ventricular pacing can be seen on the electrocardiogram (ECG) as a pacing stimulus (spike) followed by a P wave or QRS complex, respectively.

EKG: The appearance of the ECG in a paced patient is dependent on the pacing mode used, placement of pacing leads, device pacing thresholds, and the presence of native electrical activity

  • EKG Pacing Spikes: Vertical spikes of short duration, usually 2 ms.
    May be difficult to see in all leads
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