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

Patient will present as → a 37-year-old woman with a history of hypertension presents to the emergency department with complaints of shortness of breath. She was placed on a telemetry monitor. An EKG is performed and demonstrates a regular rhythm at a rate of 75 bpm, each QRS complex is preceded by a normal P wave, P waves are upright in leads I and II, and inverted in aVR, the PR interval remains constant, and each QRS complex is < 100 ms wide. 

Normal ECG 2

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

Patient will present as → a previously healthy 34-y/o long-distance runner who sustained a prolonged viral illness followed by persistent fatigue. She was evaluated 6 months later for excessive heart rate increases with minimal exertion (walking across the room) associated with palpitations. She developed near syncope with running and was unable to keep up with her mother for more than a 500-m jog. Her resting heart rate was 95 b.p.m. without orthostatic changes in pulse or blood pressure. Heart rate with minimal exercise was 190 b.p.m., which slowed gradually upon rest; this was reproducible.

Tachycardia ECG paper

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

Patient will present as → a 65-year-old woman with a past medical history notable for squamous cell carcinoma of the vallecula. Her vital signs are HR 48 bpm, BP 90/70 mmHg, RR 11 rpm, and T 98.2F.  The ECG demonstrates normal sinus rhythm with a rate of 48 beats/min.

Sinus Bradycardia

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

Atrial fibrillation

Patient will present as → a 65-year-old woman with palpitations. Her past medical history is notable for chronic obstructive pulmonary disease (COPD) for which she has been hospitalized once in the last year. On exam her T 98.4F, HR 86, BP 105/70, RR 18, SpO2 94% on room air consistent with her baseline. The ECG demonstrates low-amplitude fibrillatory waves without discrete P waves and an irregularly irregular pattern of narrow QRS complexes.

!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

Patient will present as → a 74-y/o presents for her annual physical examination and notes increasing fatigue over the prior 3 months. Her history is notable for longstanding, but now well-controlled, systolic hypertension. A physical examination demonstrates a blood pressure of 130/70 mm Hg and an irregular pulse of approximately 120 bpm at rest. The ECG shows continuous and regular atrial activation with a sawtooth pattern, most obvious in leads II, III, and aVF.

Atrial Flutter Unlabeled

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 

Patient will present as → a 68-year-old male with complaints of “a fluttering sensation in the chest”, dizziness, and a syncopal episode earlier today. Vital signs are as follows: T 98.8 F, HR 40 (irregular), BP 90/56, RR 28, O2 Sat 95% RA. The physical exam is significant for a weak pulse, widened pulse pressure, crackles auscultated at the bilateral lung bases, and cannon a-waves noted at the internal jugular veins. An electrocardiogram is obtained and is shown here.

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

First degree AV block

Patient will present as → a 45 y/o male presents for a preoperative physical. He feels well, with no significant PMH. A routine EKG is performed demonstrating a PR interval of greater than 0.20 seconds without associated disruption of atrial to ventricular conduction.

De-Rhythm 1stAVblock (CardioNetworks ECGpedia)

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 that the PR Interval will be longer than normal (over 0.20 seconds) without disruption of atrial to ventricular conduction.

  • (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

Patient will present as → a 44-year-old woman presents to the emergency room with a right radial fracture. Although she denies chest pain, a routine electrocardiogram is performed showing increasing PR intervals followed by a dropped beat.

Type I Wenckebach heart block

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

  • With second-degree heart block, Type I (Wenckebach) 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
  • The Wenckebach pattern tends to repeat in P:QRS groups with ratios of 3:2, 4:3 or 5:4

Type II: Mobitz

Patient will present as → a 72-year-old female with a history of hypertension, hyperlipidemia, and type 2 diabetes presents to the ED for three days of intermittent palpitations and shortness of breath. She states that she has had trouble climbing the stairs at home. She denies any chest pain, syncope or near syncope, cough, or other complaints. Vital signs are normal except for a pulse of 50. An EKG is performed and demonstrates marked sinus bradycardia, nonspecific ST and T wave abnormalities, and P waves which occasionally have no corresponding QRS complex without prior prolongation of the PR interval.

Type II Mobitz

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 (complete heart block)

Patient will present as → a 29 y/o man presents with extreme fatigue and shortness of breath. On physical examination, the patient has bradycardia with a regular heart rate of 32/min and normal blood pressure. EKG demonstrates completely independent atrial and ventricular activity, with no relation between the P wave and the QRS complex.

De-Rhythm 3rdAVblock (CardioNetworks ECGpedia)

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 waves do not match the QRS one for one

Bundle branch block

Patient will present as → a 32-year-old male presents to your clinic for evaluation of a recent onset of dizziness that occurred while he was upright and was generally associated with exertion. This especially concerned him since he was working as a bricklayer. During one episode at work, he found himself down on the floor but was not sure if he actually passed out. The patient smokes one pack of cigarettes per day and drinks four to six beers daily on the weekend. On physical examination, his blood pressure is 145/88 and his HR is 64 bpm and regular. He is modestly overweight, with a distribution of fat consistent with a beer belly. A 12-lead ECG showed sinus rhythm, rate 60, with an R and R’ (upward bunny ears) in V4-V6. There were no previous ECGs immediately available.

Bundle branch block

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:

  • Paroxysmal SVT – no structural abnormalities
  • AV nodal reentrant tachycardia
  • Wolff Parkinson White – Bundle of Kent fibers and delta wave on EKG
  • 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 Lead II-2

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

Patient will present as → a 25-year-old female patient with complaints of sudden onset of a pounding heartbeat, which is regular and “too rapid to count.” She reports that the episodes begin and terminate abruptly and are associated with shortness of breath and chest discomfort. On exam, the patient appears anxious, her heart rate is 170 bpm. EKG demonstrates a shortened PR interval, widened QRS, and delta waves.

De-Rhythm WPW (CardioNetworks ECGpedia)

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

Patient will present as → a 72-year-old man is admitted for exacerbation of COPD. On the third day, he reports dizziness associated with occasional chest pain. His telemetry reveals an irregular rhythm with a pulse of 124/min. The EKG demonstrates an irregularly irregular rhythm, rate of 120 bpm, discrete P waves before every QRS complex with 4 different P wave morphologies.

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

Patient will present as → a 24-year-old college student complaining of a feeling as though his heart is momentarily stopping followed by a feeling of his heart in his throat. He appears anxious and reports a weight loss of about 7 lbs. over the past 3 months. On auscultation of his heart, you notice an occasional skipped beat, followed by a brief pause and then a regular rhythm. His laboratories reveal a TSH of 0.001 and on his EKG, you notice a wide, bizarre QRS complex, greater than 0.12 sec and no identifiable p wave.

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

Patient will present as → a 44-year-old man presents with several months of nearly constant palpitations and “skipped beats.” His past medical history is notable for hypertension and obesity, treated with gastric bypass surgery 9 years prior. He denies alcohol and illicit drug use. An EKG performed to assess his current symptoms of palpitations is notable for sinus rhythm with an abnormal (non-sinus) P wave followed by a normal QRS complex. Holter monitoring documented a 19% burden of unifocal PACs.

Premature Atrial Beats

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

Patient will present as → a 30-year-old woman presented to our outpatient clinic describing a 3-year history of palpitations. An EKG performed in the clinic demonstrates several premature narrow QRS complexes without a preceding p wave.
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

Patient will present as → a 24-year-old woman presents to your clinic with complaints of anxiety along with occasional palpitations. She reports that when they occur she feels a pause in her heart followed by an extra hard beat often times felt in her throat. Laboratory evaluation reveals a TSH of 0.02. EKG demonstrates normal sinus rhythm with occasional broad QRS complexes (≥ 120 ms) with abnormal morphology.

PVC10

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

Patient will present as → a 45- year-old male admitted to the hospital because of several months of sudden onset of recurrent weakness accompanied by flushing of the face and dizzy spells. The patient also had recurrent spells of chest pain localized to the sternal area. The symptoms last for 10-15 seconds and sometimes 30 seconds to a minute and go away without treatment. During his stay in the ICU, the patient had similar symptoms several times and the monitor showed long periods of asystole with no ventricular activity.  This was associated with blood pressure drops and the patient felt dizzy. The echocardiogram is within normal limits.

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

Patient will present as → an 18-year-old student radiographer presents with a five-month history of blackouts which had latterly been occurring three or four times a day. They invariably occurred when she was standing, and from her description, there was no reason to think that the blackouts were other than vasovagal attacks, but their frequent occurrence was inconvenient. There were no other symptoms and no previous medical complaints. The pulse rate was 60 beats per minute and irregular; blood pressure was 100/60 mmHg with no postural drop. A three-minute electrocardiogram recorded during spontaneous respiration showed marked variation in the P-P intervals induced by respiration with an amplitude of 20-1%, well outside the normal range.

Sinus arrhythmia (transparent black)

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

Patient will present as → a 46-year-old female with a history of alcohol abuse is brought to the emergency room for altered mental status. Physical examination reveals a cachectic appearing female, normal breath sounds, and normal heart sounds without murmurs. In the emergency room, she becomes completely unresponsive for 1 minute and her blood pressure decreases to 50/30.

Rhythm torsade (CardioNetworks ECGpedia)


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 fibrillation

Patient will present as a 72-year-old male who develops coarse ventricular fibrillation while being monitored following an uneventful colonoscopy. He is immediately defibrillated using a biphasic defibrillator at 120 joules. The countershock is successful and he is converted to a sinus tachycardia. He has resumed spontaneous breathing.
Ventricular Fibrillation

Ventricular Fibrillation

Chaotic irregular deflections of varying amplitude and no useful contractions

  • No identifiable P waves, QRS complexes, or T waves
  • Rate 150 to 500 per minute
  • Amplitude decreases with duration (coarse VF -> fine VF)

Treat with unsynchronized cardioversion

  • Unsynchronized cardioversion - start CPR
  • Give 3 sequential shocks (120, 150, 180); assess rhythm
  • If VF persists --> do CPR and intubate
  • Administer two doses amiodarone 2-4 min. Administer 1 mg IV bolus epi every 3-5 minutes (will ↑ myocardial blood flow and ↓ cerebral blood flow and ↓ defib threshold)

An implantable cardioverter-defibrillator may be necessary

Ventricular tachycardia

Patient will present as → a 68-year-old female who arrives at the emergency department after a syncopal episode at work. Physical exam reveals an obese, unresponsive female with bilateral nonpalpable radial, carotid, and distal pedal pulses. Vital signs are as follows: T 99.4 F and BP 88/47. An emergent EKG is obtained (seen here).

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

Monomorphic Ventricular Tachycardia

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

polymorphic ventricular tachycardia

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

Patient will present as → a 78-year-old man who was admitted with 3 days history of fluttering in the chest, shortness of breath, and epigastric pain radiating to the back. His medical history includes exertional angina, unobstructed coronaries in 2015, hypercholesterolemia, and a single-chamber permanent pacemaker for complete heart block in 1995. The patient is conscious and tachycardiac with a blood pressure of 105/70 mm Hg. His chest is clear with signs of congestive heart failure. Blood chemistry results showed normal serum sodium, potassium, calcium, and magnesium. His cardiac troponin is >1000. ECG demonstrates ventricular tachycardia with a pacing spike followed by a P wave or QRS complex.

Pacemaker mediated tachycardia (CardioNetworks ECGpedia)

Atrial and ventricular pacing can be seen on the 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.
  • It May be difficult to see in all leads
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NCCPA™ CONTENT BLUEPRINT

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