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CCN > Cardiac Rhythm Analysis > Flashcards

Cardiac Rhythm Analysis Flashcards

1
Q

What are the standard limb leads?

A

Lead 1 –> RA Neg, LA Pos
Lead 2 –> RA Neg, LL Pos
Lead 3 –> LA Neg, LL Pos

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2
Q

What are bipolar and unipolar leads?

A

Three standard leads are bipolar, chest leads are unipolar

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3
Q

What does P wave represent?

A

Atrial depolarization. Normal is smooth, rounded, upright, no more than 2.5mm high

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4
Q

What does PR interval represent?

A

Time taken from atrial depolarization and delay in conduction at the AV node.

Normal is 0.12 - 0.20 seconds

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5
Q

What does QRS complex represent?

A

Ventricular depolarization. Normal is 0.06 - 0.10 secs

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6
Q

What do Q waves represent?

A

Ventricular septum depolarization.

Should be less than 1 box wide and less than 1/4 height of the following R wave, or it is pathological.

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7
Q

What does ST segment represent?

A

End of ventricular depolarization and beginning of ventricular repolarization. Starts at J point, depression or elevation is anything +- 1mm from the isoelectric line

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8
Q

What does ST elevation represent?

A

Myocardial injury, pericarditis (Global ST), ventricular aneurysm, electrolyte imbalances

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9
Q

What does ST depression represent?

A

Myocardial ischemia, NSTEMI, electrolyte imbalance

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10
Q

What does T wave represent?

A

Ventricular repolarization.
In first 1/2, cells are in absolute refractory.
Normal T wave is upright, rounded, less than 5 boxes in height and larger than P waves.

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11
Q

What does a peaked T wave represent?

A

Myocardial infarction or hyperkalemia

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12
Q

What does a negative / inverted T wave represent?

A

Myocardial ischemia, subarachnoid bleed

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13
Q

What does a flattened T wave represent?

A

Hypokalemia

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14
Q

What is the QT interval?

A

Duration of ventricular depolarization and repolarization, in NSR should not exceed 0.44 secs. Should be 1/2 of RR.

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15
Q

What does lengthened QT interval represent?

A

Longer refractory period, caused by electrolyte imbalances, hypothermia, meds (amiodarone, haloperidol, antibiotics, antidepressants)

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16
Q

Normal Sinus Rhythm: Criteria?

A

HR 60-100, regular, PR normal, QRS normal

17
Q

Sinus Bradycardia: Criteria, physiology, significance?

A

HR < 60, regular, PR normal, QRS normal

Caused by PSNS dominance, electro-conduction is normal but just slower

CO might be low, hypotension, decrease LOC, shock, ischemic chest discomfort. If HR is low an escape rhythm may take over

18
Q

Sinus Bradycardia: Etiology and treatment?

A

Myocardial infarction, meds (Ca channel blockers, beta blockers), increased ICP

Treatment if symptomatic: Atropine 0.5mg IV push (can repeat every 3-5 mins max 3mg). If ineffective consider dopamine, epinephrine, cardiac pacing

19
Q

Sinus tachycardia: Criteria, physiology, significance?

A

HR 100-150, regular, PR normal, QRS normal

Faster electro-conduction, SNS dominance

Diastolic filling time decreases as HR increases, decreased perfusion to coronary arteries, potential loss CO

20
Q

Sinus Tachycardia: Etiology and treatment?

A

Anxiety, pain, shock states, stimulants

Treat underlying cause

21
Q

Sinus arrhythmia: Criteria, physiology, significance?

A

Irregular rhythm, PR normal, QRS normal

SA node influenced by variation in PSNS, causes increase in rate during inspiration and decrease in rate during expiration.

Normal variation due to changes in intrathoracic pressure

22
Q

Sinoatrial block vs Sinus arrest: Criteria, physiology?

A

Sinus block: Missing PQRST(s), pause length is exact multiple of the underlying R-R (maps out)
SA node generates an impulse on time but is blocked from exiting, atrial cells do not depolarize.

Sinus arrest: Missing PQRST(s), pause length is not an exact multiple of underlying rhythm
SA node fails to initiate an impulse, loss of automaticity, when SA node fires again it can begin at any time

23
Q

Sinus block + arrest: Etiology and treatment?

A

Ischemia of SA node, inferior wall MI, sick sinus syndrome, meds (beta blockers, calcium channel blockers)

Review meds, if symptomatic may use atropine / pacing

24
Q

What is altered atrial automaticity?

A

Cells other than the nodal cells can abnormally initiate an impulse (ectopic impulse). If it occurs at a fast rate, it will take over the SA impulses

25
Q

What is re-entry?

A

Abnormal path of conduction where impulses from the ventricle travel back up to the atria usually through a secondary pathway and cause early atrial depolarization. Can happen several times in a circular pattern

26
Q

How does thrombus formation occur with atrial rhythms?

A

Loss of atrial kick or abnormal contraction causes blood stagnating in the atria. 48-72 hrs later a thrombus forms.

RA thrombus –> Goes into lungs, pulmonary embolus
LA thrombus –> Goes into brain, causes stroke, or elsewhere in body

27
Q

Premature atrial complex: Criteria, physiology, etiology?

A

Early beat, upright P, different shape than P waves in underlying rhythm

Cells with enhanced automaticity fire a premature ectopic beat which produces abnormal P wave. Sometimes this can depolarize the ventricle but sometimes ventricles in absolute refractory (non-conducted PAC)

Caused by excess SNS / Sympathomimetics, atrial enlargement (CHF), valvular heart disease

28
Q

Atrial tachycardia: Criteria, physiology, etiology?

A

HR 150-250, regular rhythm, normal QRS, (PR may be unable to measure)

Re-entry circuit or enhanced automaticity, ectopic site with fast rate becomes pacemaker

Caused by excess SNS / Sympathomimetics, atrial enlargement (CHF), valvular heart disease

29
Q

Atrial tachycardia: Significance?

A

1) Increases workload of the heart, increases myocardial O2 demand
2) Decreases diastolic filling time, decrease CAD blood supply

Eventually lead to myocardial ischemia and infarction

30
Q

Atrial tachycardia: Treatment?

A

If asymptomatic: Vagal manoeuvres (bearing down, carotid sinus massage), adenosine, beta / Ca blockers, amio

If symptomatic: Synchronized cardioversion

31
Q

What is synchronized cardioversion?

A

Indicated for atrial tach and other tachycardias where pts are hemodynamically unstable. Works best for re-entry rhythms, charge stops all electrical activity allowing SA node to regain firing.

Shock is synchronized with pt R wave to prevent delivering shock during the relative refractory period

32
Q

What are the joules for synchronized cardioversion?

A

Regular rhythms 50-100J

Irregular rhythms 120-200J

33
Q

Atrial flutter: Criteria, physiology, etiology?

A

Atrial rate > 250, saw tooth atrial pattern (F waves)

Predominant re-entry rhythm, ventricular response is dependent on number of atrial impulses conducted through AV node

Caused by lung + heart disease: chronic lung disease, valvular heart disease, myocardial infarction / ischemia, post cardiac surgery

34
Q

Atrial flutter: Paroxysmal vs peristent?

A

Paroxysmal –> Self terminate in less than 7 days

Persistent –> >7 days

35
Q

Atrial flutter: Treatment?

A

Goal of rate and rhythm control.

Rate control: Metoprolol, diltiazem. Target to lower HR to < 100, anticoagulants recommended if > 48hrs

Rhythm control: Amiodarone or synchronized cardioversion if unstable (only if < 48hrs)

36
Q

Atrial fibrillation: Criteria, physiology, etiology?

A

Irregular rhythm, f waves

Enhanced automaticity or re-entry pathway, AV node is bombarded with impulses

Caused by lung + heart disease: chronic lung disease, valvular heart disease, myocardial infarction / ischemia, post cardiac surgery

37
Q

Atrial fibrillation: Treatment?

A

Goal of rate and rhythm control.

Rate control: Metoprolol, diltiazem. Target to lower HR to < 100, anticoagulants recommended if > 48hrs

Rhythm control: Amiodarone or synchronized cardioversion if unstable (only if < 48hrs)

38
Q

Multifocal atrial tachycardia: Criteria, physiology, etiology?

A

HR > 100, irregular, changing P waves, at least 3 different P shapes, normal QRS

Many ectopic sites in the atria depolarizing atrial tissue. Pacemaker “wanders” (if HR < 100, called wandering pacemaker )

Caused by lung + heart disease: chronic lung disease, valvular heart disease, myocardial infarction / ischemia, post cardiac surgery

39
Q

Multifocal atrial tachycardia: Treatment?

A

Same as A flutter and A fib, but occasionally adenosine may be given for diagnostic purposes

CCN (27 decks)

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