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Cardiovascular Exam II > Arrhythmias > Flashcards

Arrhythmias Flashcards

1
Q

One type of arrhythmia is an irregular rhythm, usually caused by multiple, active automaticity sites which are often parasystolic. What does it mean to be parasystolic?

A

Insensitive to overdrive suppression

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2
Q

One type of arrhythmia is an irregular rhythm, usually caused by multiple, active automaticity sites which are often parasystolic. What are the 3 main types of irregular rhythms?

A

Wandering pacemaker

Multifocal atrial tachycardia (MAT)

Atrial fibrillation

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3
Q

Etiology of wandering pacemaker

A

Produced by pacemaker activity wandering from SA node to nearby atrial automaticity foci

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4
Q

EKG changes with wandering pacemaker

A

Produces cycle length variation and variation in P’ shape

Overall rate is in normal range

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5
Q

What type of arrhythmia mimics a wandering pacemaker, but with a rate >100bpm?

A

Multifocal atrial tachycardia

[see varying P’ shape, atrial rate exceeds 100, irregular ventricular rhythm]

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6
Q

Multifocal atrial tachycardia is found in pts with what conditions?

A

Primarily COPD or digitalis toxicity

[overall association with lung disease includes COPD, pneumonia, ventilator theophylline; also associated with beta agonists, electrolyte abnormalities like hypokalemia, hypomagnesemia, sepsis]

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7
Q

Arrythmia caused by continuous, rapid firing of multiple atrial automaticity foci in which no single impulse depolarizes the atria completely and only the occasional, random atrial depolarization reaches the AV node to be conducted to the ventricles

A

Atrial fibrillation

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8
Q

“______” refers to a beat or rhythm response of an automaticity focus to a pause in pacemaking activity

A

Escape

[i.e., an escape rhythm = automaticity focus escapes overdrive suppression to pace at its inherent rate; escape beat = automaticity focus transiently escapes overdrive suppression to emit one beat]

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9
Q

A ____ escape rhythm becomes the dominant pacemaker after sinus arrest, with an inherent range of _____-_____

A

Atrial; 60-80

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10
Q

A junctional escape rhythm (aka idiojunctional rhythm) occurs after sinus arrest AND failure of atrial automaticity foci; or if there is a complete conduction block in the proximal AV node. What is the inherent range of this type of escape rhythm, and what other changes are seen on ECG?

A

Inherent range 40-60

Produces a series of lone QRS complexes, may produce retrograde atrial depolarization —> inverted P’ waves with upright QRS

[note that inverted P’ wave may be before, after, or buried within QRS]

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11
Q

Inherent rate and circumstances in which you might see a ventricular escape rhythm (aka idioventricular rhythm)

A

Inherent rate = 20-40

Occurs with complete conduction block in ventricular system BELOW the AV node; or total failure of SA node and all automaticity foci above the ventricles

[this is RARE — and referred to as downward displacement of the pacemaker]

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12
Q

Specific ventricular escape rhythm in which pacing is so slow that pt loses consciousness and you must constantly maintain/monitor their airway

A

Stokes Adams Syndrome

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13
Q

Upon transient sinus block of one pacemaking stimulus from the SA node, if the pause is sufficient enough, you may see an atrial _____ _____

A

Escape beat

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14
Q

ECG finding associated with atrial escape beat

A

P’ wave that is different shape/appearance than others; the SA node then quickly resumes pacing and tracing returns to normal

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15
Q

If the SA node misses one pacing cycle, and there is no atrial focal response, the result is a junctional escape beat. What is the resulting change on ECG?

A

There may bay retrograde atrial depolarization, resulting in inverted P’ before or after QRS

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16
Q

If the SA node and all atrial and junctional foci fail, there may be a resulting ventricular escape beat. What usually causes this?

A

Burst of parasympathetic activity, which depresses SA node, atrial, and junctional foci, leaving ventricular foci to respond

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17
Q

Premature beats occur when there is an irritable focus that spontaneously fires a single stimulus. What are some potential causes of irritable atrial or junctional foci?

A 
Epinephrine from adrenals
Sympathetic stimulation (or decreased parasympathetic stim)
Caffiene, amphetamines, cocaine, other stimulants
Beta 1 agonists
Excess digitalis
Toxins
Ethanol
Hyperthyroid
Stretch
O2 (to some extent)
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18
Q

ECG findings with premature atrial beats

A

P’ wave earlier than expected (appears different from sinus-generated P) — will be upright when focus is close to SA node, inverted when further away

The SA node then resets to continue pacing one cycle length from premature stimulus (requires that dominant center is depolarized by premature beat)

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19
Q

Why might you see slightly widened QRS following a premature atrial beat?

A

Aberrant ventricular conduction because the ventricles were still partially refractory when the premature beat occurred

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20
Q

Why might you see a dropped QRS following a premature atrial beat? What ECG finding does this mimic?

A

If premature atrial beat is not conducted through AV node, may see dropped QRS; mimics heart block

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21
Q

What is it called when you see a premature atrial beat coupled to the end of each normal cycle?

A

Atrial bigeminy

[atrial trigeminy is coupled to the end of every 2 cycles]

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22
Q

What causes a premature junctional beat? What is seen on ECG?

A

AV junction spontaneously fires stimulus that depolarizes ventricles and sometimes retrograde to atria (inverted P’)

Often see widened QRS because ventricles are still partially refractory

AV junctional bigeminy (PJB after each normal cycle); AV junctional trigeminy (PJB after every 2 cycles)

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23
Q

Which automaticity foci are considered the most sensitive to O2?

A

Ventricular automaticity foci - when they sense low O2 they emit a premature ventricular beat (may occur with airway obstruction, absence of air d/t things like drowning, minimal oxygenation at lungs, reduced cardiac output, poor coronary blood supply, etc.)

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24
Q

Other than low O2, what are some causes of premature ventricular beats?

A 
Hypokalemia
Mitral valve prolapse
Stretch
Myocarditis
Sometimes beta 1 agonists
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25
Q

Premature ventricular beats usually occur early in the cycle, and are easily recognized by what characteristics on ECG?

A

Great width and amplitude of QRS, usually opposite the polarity of the other QRS complexes

Premature ventricular beats do NOT depolarize the SA node, so SA node continues pacing on schedule, but the ventricles are refractory d/t extra beat so a pause is seen

ST-T wave moves in opposite direction of QRS

Can also see bigeminy or trigeminy

Can be unifocal (QRS’s appear uniform) or multifocal (multiple QRS morphologies present)

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26
Q

____+ premature ventricular beats in a minute is considered pathologic

A

Six

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27
Q

______ ______ = premature ventricular contractions coupled to a long series of normal cycles (dual rhythm with pacing from 2 sources)

A

Ventricular parasystole

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28
Q

Condition characterized by a run of 3+ PVCs in rapid succession (rate of 120-200), usually regular with wide QRS

A

Ventricular tachycardia

[sustained V-tach when >30 seconds]

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29
Q

If a PVC falles on a ____ wave, it potentiates ischemia in something called ______ phenomenon, which may result in dangerous arrhythmias

A

T; R on T

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30
Q

Tachyarrhythmias are rapid rhythms originating in very irritable automaticity foci. What are the 3 types of tachyarrhythmias and their associated rates?

A

Paroxysmal tachycardia = 150-250 bpm

Flutter = 250-350 bpm

Fibrillation = 350-450 bpm

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31
Q

Paroxysmal atrial tachycardia and paroxysmal junctional tachycardia can not typically be distinguished, and are usually treated the same way anyway, so they can generally be referred to using what blanket term?

A

Paroxysmal Supraventricular Tachycardia

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32
Q

ECG findings with paroxysmal supraventricular tachycardia

A

P’ waves that appear different from normal P waves, otherwise normal P’-QRS-T cycles; when paroxysmal junctional tachycardia may see retrograde atrial depolarization with inverted P’ before, after, or buried in QRS

May see widened QRS d/t aberrant ventricular conduction (aka still refractory)

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33
Q

ECG findings with paroxysmal atrial tachycardia with AV block

A

Rapid rate, spiked P’ waves

2:1 ratio of P’:QRS

34
Q

What should you suspect as the etiology for paroxysmal atrial tachycardia with AV block?

A

Digitalis excess or toxicity

35
Q

Paroxysmal junctional tachycardia may lead to AV nodal re-entry tachycardia (AVNRT). What does that mean?

A

Continuous re-entry circuit develops (including AV node and lower atria) and rapidly paces the atria and ventricles; No P waves are seen

Mechanism:

  1. Premature atrial impulse enters slow path but is blocked at the fast path
  2. Impulse is conducted forward through slow path
  3. Ventricles activated in synchrony
  4. Impulse is conducted backward through fast path
  5. Impulse activates atria retrogradely and re-enters slow path
36
Q

Characteristic ECG pattern of paroxysmal ventricular tachycardia

A

Enormous, consecutive PVC-like complexes

SA node is still pacing, but it will be buried in the tracing

Signs of AV dissociation or extreme right axis deviation are also characteristic

37
Q

Paroxysmal ventricular tachycardia is most likely to occur in what pt populations?

A

Elderly pts with ischemia of ventricles

38
Q

Type of polymorphic ventricular tachycardia, characterized by shifting sinusoidal waves on EKG; can lead to ventricular fibrillation

A

Torsades de pointes

39
Q

Causes of Torsade de Pointes

A 
Hypokalemia
K+ channel blockers
Congenital abnormalities (long QT syndrome)
40
Q

Arrhythmia characterized by “sawtooth” appearance on ECG representing atrial depolarization

A

Atrial flutter

41
Q

_____ maneuvers increase ____ node refractoriness allowing fewer flutters to be conducted to ventricles and may help to reduce symptoms associated with atrial flutter

A

Vagal; AV

42
Q

______ flutter produces a series of smooth sine waves, rarely self resolves, and almost always precedes a deadly arrhythmia

A

Ventricular flutter (deadly arrhythmia it leads to is ventricular fibrillation)

43
Q

What usually triggers Afib?

A

Usually initiated by parasystolic foci in the pulmonary vein ostia of the LA

44
Q

ECG appearance of Afib; what leads are best to identify it?

A

Appears as wavy baseline without identifiable P or P’ waves; QRS response is not regular and may be fast or slow

“Irregularly irregular”

Best Leads = II, III, aVF

45
Q

Condition characterized by totally erratic EKG without identifiable waves with gradually diminishing amplitude as the heart fails

A

Ventricular fibrillation

46
Q

Most common type of ventricular pre-excitation syndrome

A

Wolff-Parkinson-White syndrome

47
Q

WPW is characterized by abnormal fast accessory condition pathway from the atria to the ventricle (bundle of ____) which bypasses the rate-slowing AV node; thus the ventricles begin to partially depolarize earlier, leading to characteristic _____ wave with ______ QRS and _____ PR interval

A

Kent; delta; widened; shortened

48
Q

WPW may result in re-entry circuit, leading to _____ ____

A

Supraventricular tachycardia

49
Q

Condition in which AV node is bypassed by extension of the anterior internodal tract; absence of conduction delay in AV node allows “James” bundle to conduct atrial depolarization directly to the His bundle without delay

A

Lown-Ganong-Levine syndrome

50
Q

Lown-ganong-levine syndrome allows atrial conduction be transmitted directly to the His bundle without delay. This may lead to what complication?

A

Rapid atrial arrhythmias like atrial flutter

51
Q

Autosomal dominant disorder leading to increased risk of ventricular tachyarrhythmias and SCD, most common in asian males

A

Brugada syndrome

52
Q

ECG findings associated with Brugada syndrome

A

RBBB with ST elevation in V1, V2, V3

[these pts need pacemakers/ICD]

53
Q

Condition characterized by stenosed anterior descending coronary artery in which angioplasty is necessary to prevent impending MI

A

Wellens syndrome

54
Q

Long QT syndrome predisposes to dangerous ventricular arrhythmias. What defines a QT segment as long?

A

A long QT segment exceeds 1/2 the cardiac cycle

55
Q

What typically causes long QT syndrome? What is the major complication of concern?

A

Typically caused by ion channel defects, but can also be drug-induced (class IA and class III antiarrhythmics, abx like macrolides, antipsychotics like haloperidol, antidepressants like TCAs, anti-emetics like odansetron)

Major complication of concern is increased risk of SCD d/t torsade de pointes

56
Q

COPD is associated with ______ hypertrophy, ____ axis deviation, and ______ (arrhythmia)

A

RV; Right; MAT

57
Q

ECG findings with pulmonary embolus

A

[tachycardia, non-specific ST-T changes]

Large S wave in lead I

ST depression in lead II

Large Q wave in lead III (with T wave inversion in V1-4)

Transient RBBB

58
Q

ECG findings in moderate to severe hyperkalemia

A

Moderate —> peaked T wave, wide flat P wave, wide QRS

Severe —> No P waves, QRS more widened

May see increased PR interval

59
Q

ECG findings in hypokalemia

A

U waves

Increased QT interval

Flat or inverted T wave

60
Q

ECG findings in hypercalcemia

A

Short QT

61
Q

ECG findings in hypocalcemia

A

Prolonged QT

62
Q

Medical conditions/situations associated with bradycardia

A

Normal people, healthy athletes, physiologic components to sleep, fright, carotid sinus massage, carotid hypersensitivity, ocular pressure (glaucoma), obstructive jaundice (effect of bile salts on SAN), sliding hiatal hernia, valsalva maneuver

diseases of atrium or SAN — CAD, inflammation, invasive neoplasm, cardiomyopathy, muscular dystrophy, amyloidosis

Drugs like digitalis, quinidine, HTN drugs like clonidine, methyldopa, reserpine, beta blockers

Acute inferior MI (d/t increased vagal tone), ischemia, acidosis, SSS, convalescence from digitalis toxicity

63
Q

What is the most common cause of an unexplained pause on ECG?

A

Nonconducted premature atrial contraction (PAC)

64
Q

What med is given in sinus bradycardia if HR is <45-50 with hemodynamic compromise/unstable acute situations?

A

Atropine

can also give epinephrine, isoproterenol, or pacemaker

[note side effects = urinary retention, abdominal distention]

65
Q

______ = property of a cardiac cell to depolarize spontaneously during phase 4 of AP/leads to generation of an impulse

A

Automaticity

66
Q

Treatment of PACs

A

Only if symptomatic — look to reverse the cause (stress, alcohol, tobacco, coffee, COPD, CAD)

Can give beta blockers — metoprolol

67
Q

Tx for MAT

A

Focus on underlying cause

IV verapamil (calcium channel blockers)

68
Q

Treatment for AVNRT (SVT)

A

Adenosine (try valsalva first to slow HR); can also give diltiazem, beta blocker, or shock if needed

69
Q

Treatment of PVCs

A

If stable, do nothing

If symptomatic or in setting of ACS — give metoprolol

If unstable (in setting of MI, acidosis, etc.), give antiarrhythmic like amiodarone, lidocaine, procainamide, etc.

70
Q

Fusion beats in the setting of ventricular tachycardia are characteristic of ______ syndrome

A

Dressler

71
Q

A 63 y/o man has been in the ED for 1.5 hours with hx of CP. EKG reveals changes consistent with anterior AMI. The pt suddenly becomes cool, clammy, and confused with systolic BP of 70. EKG at that time reveals ventricular tachycardia. What do you do?

A

Cardioversion required d/t sudden change in status

72
Q

Tx for Vfib

A

CPR, defibrillation

73
Q

Torsade de pointes tx

A

MgSO4

Overdrive pacing

Isoproternol

74
Q

If the clinical vignette ever mentions cancer or malignancy, the first electrolyte that should come to mind is _____

A

Calcium

[hypercalcemia is associated with malignancy, look for short QT interval and/or short ST segment on ECG]

75
Q

What change in pH reduces the threshold for VF?

A

Acidosis

76
Q

ECG findings in hypothermia

A

Bradycardia and J wave (Osborne wave)

77
Q

ECG changes with cor pulmonale

A

Tall, pointed P waves [p-pulmonale]

78
Q

ECG changes with cerebral hemorrhage

A

Impressive ST-T changes

[tall T waves, inverted wide T waves, etc.]

79
Q

Whenever you see widespread flattening or mild inversion of T waves without associated ST segment displacement, always think of __________

A

Hypothyroidism

80
Q

Whenever you see widespread flattening or mild inversion of T waves without associated ST segment displacement, always consider hypothyroidism.

The other most constant ECG finding in myxedema (severe hypothyroid) is low voltage of the ________. Sinus bradycardia is less often seen.

A

QRS complex

Cardiovascular Exam II (11 decks)

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