8/5- Arrhythmias Flashcards Preview

_MS2 Cardio > 8/5- Arrhythmias > Flashcards

Flashcards in 8/5- Arrhythmias Deck (62):
1

What is a normal QRS complex time/width? Long?

Normal is ~120 ms, long is anything over about 140

2

What are the 3 steps in diagnosing any arrhythmia?

1. Determine if the QRS complexes are narrow or wide

2. Determine if the QRS complexes or regular or irregular (distance of more than 1/2 a box between complexes)

3. Determine if P waves or evidence of atrial activity are present (relation between P wave and QRS) 

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3

What are possible arrhythmias if QRS complexes are narrow and regular?

- Sinus tachycardia

- Atrial tachycardia

- Atrial flutter

- AVNRT

- AVRT

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4

What are possible arrhythmias if QRS complexes are narrow and irregular?

- MAT

- Atrial flutter with variable conduction

- Atrial fibrillation

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5

What are possible arrythmias if QRS complexes are wide?

- SVT with BBB

- Ventricular tachycardia

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6

What is this? Analyze 

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- HR ~ 150 bpm (tachycardia)

- Positive upright (normal) P waves in front of every QRS complex (1:1 P:QRS ratio)

- QRS is nice and slim; no conduction problem down from the atrium

- Limited analysis because there's only 1 lead, but this P wave morphology may indicated sinus wave tachycardia

Most likely: sinus tachycardia

- This is just a rate problem

7

What is sinus tachycardia typically a response to?

Sinus tachycardia is almost always a physiologic response

8

What may cause sinus tachycardia?

- Hypotension

- Hypovolemia/anemia/acute bleed

- MI/depressed EF/tamponade

- Hypoxemia

- Fever

- Anxiety/pain

- Medications

- (Hyperthyroidism)

9

What other types of sinus tachycardia are present (rarely)?

- Sinus node reentrant tachycardia

- Non paroxysmal sinus tachycardia

- Postural orthostatic tachycardia syndrome (POTS)

10

What is this? 

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- P wave present before every QRS complex (this is probably ~ lead II: P waves are negative)

- P wave looks a little uncharacteristic (although only 1 lead here): ectopic P waves (anything originating from any other place than the sinus node)

Ectopic atrial tachycardia

11

What are some common causes of atrial tachycardia?

- Structural (atrial) heart disease/diseased atria

- Sympathetic stimulation

- Toxins/drugs

12

What is the heart rate range for atrial tachycardia?

120-250 bpm (typically ~ 160)

13

T/F: Atrial tachycardia typically causes hemodynamic compromise?

False; atrial tachycardia usually does NOT cause hemodynamic compromise

14

Treatments for atrial tachycardia?

- Withdraw sympathetic stimuli/drugs

- Rarely (if ever) use antiarrhythmics

- Often does not respond to cardioversion

15

What is this? Analyze

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Atrial Tachycardia with Block (PAT with Block)

- Arrows pointing at P waves (negative here)

- No 1:1 conduction here; P waves too fast and ventricles can't respond to each one. You basically see conduction every 4th P wave

- "Block" from inability of AV node to handle atrial tachycardia rate; may be protective, but bad if it causes heart rate to drop too low

16

What could cause atrial tachycardia with block (PAT with block)?

Digoxin toxicity

17

What is a common treatment for really any type of tachycardia?

Catheter ablation

18

What is this? Analyze

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- Continuous undulation of isoelectric line; no straightish segment between P waves

- Sawtooth line pattern of isoelectric line

Atrial flutter

19

What does the conduction pattern look like in atrial flutter?

Depolarization is traveling continuously in an atrial circuit; there's basically no free atrial activation that would create straight isoelectric line between P waves 

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20

What may cause atrial flutter?

Diseased or dilated atria

21

What is the heart rate in atrial flutter?

Usually 300 (with 2:1 AV block)

22

Treatment for atrial flutter?

- Unstable: synchronized cardioversion (shock the pt)

- Slow AV conduction (Metoprolol, Verapamil or diltiazem, not digoxin acutely)

- Convert back to sinus

- Recently, anticoagulate like AF (stagnant blood in parts of the atria may cause clots... -> brain)

23

What is this? Analyze 

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- Narrow complex tachycardia; regular

- Don't see clear P wave

Narrow complex QRS tachycardia with no regular P wave; there are 2 possibilities from here:

- AVNRT or AVRT??

24

What is AVNRT (name)? What is the conduction pathway?

AV Nodal Re-Entrant Tachycardia (AVNRT)

- Rhythm originates in AV node

- Atria and ventricles are activated almost simultaneously, thus P and QRS occur almost the same time (P waves can't be observed) 

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25

What causes AVNRT?

"Micro-reentrant pathway"

- Usually "paroxysmal", often triggered by PAC

- Rarely correlated with any heart disease; occurs in structurally normal hearts (?)

26

Treatment for AVNRT?

- Unstable: cardiovert

- Block AV conduction:

---Vagal-enhancing maneuvers

---Adenosine (6 mg,12,12): almost always works

---Verapamil or Diltiazem

---Beta blockers

- Ablation

27

What is this? Analyze

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- Cousin to AVNRT, but this AVRT

- There is a P wave (outside the QRS; commonly not seen)

28

What is AVRT? What is the conduction pathway?

AV Re-entrant Tachycardia (AVRT)

- Both atria and ventricle are equal participants in tachycardia

- Conduction happens in reverse from ventricle to atrium; don'c contract simultaneously (ventricles first)

- May see retrograde P wave distorting ST segment

- This is orthodromic (anti-dromic could have reversed conduction path and weird ventricle pattern) 

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29

What causes AVRT?

"macro reentrant loop" involving bypass tract

- Usually "paroxysmal"

30

Orthodromic conduction (shown earlier) occurs in ___% of cases while antidromic (may resemble VT) occurs in ___%

Orthodromic: 90-95%

Antidromic: 5%

31

Treatment for AVRT?

- Unstable: cardiovert

- Stable: block or slow AV node conduction

- Ultimately: ablation

32

The following distinguishing characteristics of narrow complex regular tachycardia point to what types of arrhythmias?

- Normal P waves ->

- Abnormal P waves ->

- Flutter waves ->

- No atrial activity ->

- Normal P waves -> sinus tachycardia

- Abnormal P waves -> atrial tachycardia

- Flutter waves -> atrial flutter

- No atrial activity -> AVNRT or AVRT

33

What is this? 

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Multifocal Atrial Tachycardia (MAT)

34

Conduction pattern in MAT?

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35

How can MAT be diagnosed?

- 3 or more distinct P waves

- Ventricular rate 100

36

What cuases MAT?

Usually occurs in pts with pulmonary disease, esp COPD

37

Treatment for MAT?

- TREAT UNDERLYING DISEASE

- Try to decrease sympathomimetics

- Attempts to suppress arrhythmia or block AV conduction are usually futile*

38

What is this? 

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Atrial flutter (with variable conduction)

39

What is the conduction pattern in atrial flutter?

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40

What is this? 

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Atrial fibrillation

41

What is the conduction pattern in atrial fibrillation?

- May also be due to focus in pulmonary vein 

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42

What may cause atrial fibrillation?

- HTN

- Ischemia/CAD

- Atrial dilation (MV disease, etc)

- Toxins

- Pericarditis

- Pulmonary emoblus

- Hyperthyroidism

- Vagal or sympathetic mediated

- (Pulmonary vein)

Many AF causes may be caused by focus in pulmonary vein

43

Nomenclature in atrial fibrillation:

- Paroxysmal, episodic:

- Persistent:

- Permanent:

Nomenclature in atrial fibrillation:

- Paroxysmal, episodic: AF converts to NSR spontaneously

- Persistent: AF terminates only after intervention

- Permanent: AF resists attempts to restore NST

44

Treatment for atrial fibrillation?

- Unstable: cardiovert

- Stable: slow ventricular response rate or electively cardiovert

- If in afib > 48 hrs or unknown time, anticoagulate or obtain TEE to r/o thrombus; then cardioversion and/or ibutilide

45

Recap: The following distinguishing characteristics of narrow irregular tachycardia point to what types of arrhythmias?

- Multiple different P waves ->

- Flutter waves ->

- No atrial activity ->

Narrow irregular tachycardias:

- Multiple different P waves -> MAT

- Flutter waves -> atrial flutter

- No atrial activity -> atrial fibrillation

46

What is this? Analyze

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"Boringly regular" QRS complexes in WCTs due to SVT

47

What is this? Analyze 

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Slightly irregular QRS complexes in VT

48

What is the conduction pattern in atrial and ventricular dissociation in ventricular tachycardia?

(P wave dissociation/AV dissociation)

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49

What is this? Analyze

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VT with AV dissociation

50

What is the conduction pattern in ventricular tachycardia?

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51

What may cause ventricular tachycardia?

- Acute ischemia or acute myocardial infarction

- Reentry around old scar or aneurysm

- Medications that prolong QT interval

52

Treatment for ventricular tachycardia?

- Unresponsive or pulseless: defibrillation

- Unstable: synchronized cardioversion

- Stable: antiarrhtyhmic agents

53

What is this?

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Ventricular tachycardia: Torsades de Pointes

54

What is this?

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Atrial tachycardia with block; flutter

55

What is this? 

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Multifocal atrial tachycardia

- see 3 or more morphologies

56

What is this?

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Sinus tachycardia with bundle branch block

- Rate here is little more than 100

- Note aVL and V1 leads

57

What is this? 

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?

58

What is this? 

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?

59

What is this? 

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?

60

What is this? 

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?

61

Side effects of antiarrhythmic therapy?

- Negative inotropy

- QT prolongation and torsades de pointes

- Pro-arrhythmic

* Suppressing PVCs increases death

* Treating atrial fibrillation by trying to suppress the arrhythmia is not better than anticoagulating and controlling the rate

* AICDs (defibrillators) are better than antiarrhyhmics in pts with ventricular tachycardia (VT)

62

What is Amiodarone?

Drug for antiarrhythmic therapy

- Beta blocking, Ca-channel blocking, and direct; acts on SA node, AV node, atrial and ventricular tissues

- When starting: follow for bradycardia and heart block

- Longer term (q6 mo): liver function tests, thyroid function tests (esp TSH), CXR (pulmonary fibrosis)

- Important drug interactions: increases INR, increases digoxin level

- Useful loading dose: bolus, then 1 mg/kg/hr; 400 BID-TID

- Usual maintenance dosing:

---Atrial arrhythmias; 100-200 qD

---Ventricular arrhythmias: 200-400 qD