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PCCN > Cardiac Rhythms > Flashcards

Cardiac Rhythms Flashcards

1
Q

Sinus node
1- where
2- rate of automaticity

A

1- upper right atrium

2- 60 to 100 beats/min

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2
Q

AV node
1- where
2- rate of automaticity

A

1- low right atrium, near tricuspid valve

2- 40 to 60 beats/min

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3
Q

AV node primary functions (3 total)

A

1- slows conduction of impulses from atria to ventricles to allow time for atria to empty/contract
2- acts as backup pacemaker if Sinus node fails
3- protects the ventricles by screening out dangerously rapid atrial impulses

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4
Q

Bundle of His location

A

at the bottom of the AV node, leading to R/L bundle branches

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5
Q

Bundle Branches

A

Right –> Right ventricle, Left –> Left ventricle (has two devisions: anterior and posterior fascicles)

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6
Q

Purkinje fibers
1- location
2- rate of automaticity

A

1- spread out from the bundle branches along the ventricles

2- 20 to 40 beats/min

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7
Q

P wave
1- what it represents on ECG
2- duration

A

1- atrial depolarization 2- less than 0.11 second

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8
Q

QRS complex
1- what it represents on ECG
2- duration

A

1- ventricular depolarization

2- 0.04 to 0.10 seconds

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9
Q

T wave 1- what it represents

A

1- ventricular repolarization

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10
Q

PR interval 1- what it represents 2- duration

A

1- time required for the impulse to travel through the atria, AV junction, to the purkinje system
2- 0.12 to 0.20 seconds

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11
Q

QT interval 1- what it represents 2- duration

A

1- duration of ventricular depolarization and repolarization
2- Men < 0.45 seconds Women < 0.46 seconds

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12
Q

ECG graph paper seconds / mV
HORIZONTAL (seconds) 1- small box 2- large box
VERTICAL (millivolts, millimeter) 1-small box 2- large box

A

HORIZONTAL 1- small box = 0.04 sec 2- large box = 0.20 sec

VERTICAL 1- small box = 0.1 mV (1 mm) 2- large box = 5 mV (5 mm)

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13
Q

Treatment(s) of SYMPTOMATIC bradycardia (HR<60)

A

Atropine 0.5mg IV, temporary or permanent pacing, DC potentially responsible medications, minimize vagal stimulation

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14
Q

Treatment of sinus arrest
(sinus arrest is when more than one sinus impulse in a row fails to form [vs sinus pause- in which only one impulse fails to form])

A

DC potentially responsible medications, minimize vagal stimulation
IF periods of sinus arrest frequent & cause hemodynamic compromise- Atropine 0.5mg IV, temporary or permanent pacing

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15
Q 
Treatment of atrial tachycardia 
1- acute treatment
--Stable
--Unstable
2- ongoing management
A
  1. Acute Treatment:
    - IV beta-blocker, diltiazem or verapamil if hemodynamically stable
    - synchronized cardioversion if hemodynamically unstable
    - Adenosine to restore SR or Dx tachycardia
  2. Ongoing Management:
    - Catheter ablation
    - oral BB’s, diltiazem, verapamil
    - flecainide or propafenone
    - sotalol or amiodarone
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16
Q

Treatment of SVT of unknown mechanism

A
  • vagal maneuvers
  • adenosine (6mg rapid IVP, may repeat w/ 12mg if necessary)
  • synchronized cardioversion
  • IV verapamil or diltiazem (hemodynamically stable)
  • IV BB’s (hemodynamically stable)
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17
Q

Acute Treatment of Atrial Flutter

A
  • pharmacological cardioversion w/ PO dofetilide or IV ibutilide
  • IV or PO BB’s, diltiazem, or verapamil (for rate control if hemodynamically stable)
  • synchronized cardioversion
  • IV amiodarone for rate control
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18
Q

Classifications of A Fib

A

Paroxysmal: episodes that terminate spontaneously or w/ intervention within 7 days of onset
Persistent: episodes that last more than 7 days
Long-standing persistent: continuous AF lasting > 12 months
Permanent: >23 months & decision made to stop attempts to restore/maintain SR
Recurrent: 2+ more episodes

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19
Q

CHA(2)DS(2)VASc score (0 - 10)

A 
C = CHF
H = hypertension
A(2) = age> 75 years (2 pts) 
D = diabetes
S(2) = Hx stroke, TIA, thromboembolism (2 pts)
V = vascular disease (prior MI, PAD,  aortic plaque)
A = age 65-74
Sc = sex category female
20
Q

What does the CHA-DS-VASc score used to assess?

A

Stroke risk in AF patients; can be used to assess type of anti-thrombotic therapy

21
Q

Idioventricular rhythm

  1. where it originates
  2. rate
  3. why it may occur
A
  1. originates- ectopic focus in the ventricles
  2. rate- < 50 beats/min
  3. occurs when the sinus node and junctional tissue fail to fire or fail to conduct impulses to the ventricle
22
Q

Ventricular tachycardia (VT) classification

  1. duration
  2. morphology
A
  1. duration
    - nonsustained = lasts < 30 seconds
    - sustained = lasts > 40 seconds
    - incessant = present most of the time
  2. morphology
    - monomorphic = QRS have same shape
    - polymorphic = QRS have varying shapes
    - bidirectional = alternating upright & negative QRS complexes
23
Q

What is Torsades de pointes (“Twisting of the points”)

A

polymorphic VT that occurs in the presents of a long QT interval

24
Q

Treatment of VT (w or w/out a pulse)

A

Pulse Present:
- Stable: first choice is amiodarone (then, lidocaine or procainamide)
- Unstable: synchronized cardioversion
No Pulse: immediate defibrillation

25
Q

Second Degree AV Block: Type I (“Wenckebach”)

A

“longer long longer drop”

  • occurs in the AV node
  • progressive increase in conduction times until one impulse fails to conduct (“dropped”) = PR intervals gradually lengthen until one P wave fails to conduct and is not followed by a QRS, then cycle repeats
26
Q

Second Degree AV Block: Type II

A
  • occurs below the AV node in the bundle of His or bundle branch system
  • sudden failure of the conduction of an atrial impulse to the ventricles without progressive increases in conduction time of consecutive P waves
  • irregular rhythm d/t blocked beats
  • periodically, a p wave is not followed by a QRS
  • QRS almost always wide (d/t associated BBB)
  • more serious than Type I (d/t higher incidence of associated sx’s & progression to complete AVB)
27
Q

Types of temporary pacing

A
  1. Transvenous
  2. Epicardial
  3. External (Transcutaneous)
28
Q

How is transvenous pacing done?

A

by percutaneous puncture of a large vein (IJ, subclavian, AC or femoral) and advancing a pacing lead into the apex of the right ventricle, the lead is attached to an external pulse generator kept on the patient or at bedside

29
Q

How is epicardial pacing done?

A

electrodes are placed on the atria or ventricles during cardiac surgery

30
Q

What are the two components of a cardiac pacing system?

A

1- pulse generator

2- pacing leads

31
Q

What are the two main functions of a pacing system?

A

capture and sensing

32
Q

What does capture mean (re: pacing systems)?

A

capture means that a pacing stimulus results in depolarization of the chamber being paced

33
Q

What are some possible reasons that capture would NOT occur?

A

if the distal tip of the pacing lead is not in contact with healthy myocardium capable of responding to the stimulus; pacing in infarcted tissue usually prevents capture; or if the catheter is not in direct contact with myocardium

34
Q

What does sensing mean (re: pacing systems)?

A

sensing means that the pacemaker is able to detect the presence of intrinsic cardiac activity

35
Q

What is asynchronous (fixed-rate) pacing and why can it be dangerous?

A

when the pacemaker paces at the programmed rate regardless of intrinsic cardiac activity
it can result in competition between the pacemaker & the hearts own electrical activity
asynchonous pacing in the ventricle is unsafe b/c of the potential for pacing stimuli to fall during repolarization & cause VF

36
Q

What does demand mean (re: pacing systems)?

A

Demand means that the pacemaker paces only when the heart fails to depolarize on it own
In demand mode, the pacemaker’s sensing circuit is capable of sensing intrinsic cardiac activity & inhibiting pacer output when intrinsic activity is present

37
Q

How do you confirm capture with external (transcutaneous) pacing?

A

the presence of a pulse with every pacing spike confirms ventricular capture

38
Q

How does one measure the QTc?

A
  • using the Bazett formula

- measured QT interval DIVIDED BY the sqaure root of the R-R interval

39
Q

Best leads for monitoring wide QRS rhythms?

A

V1 and V6 (or their bipolar substitutes- MCL1 and MCL6)

40
Q

PAC (premature atrial contraction) defining features:

A
  • narrow QRS
  • upright P wave
  • different morphology?
41
Q

PJC (premature junction contraction) defining features:

A
  • narrow QRS

- absent/inverted P wave

42
Q

PVC (premature ventricular contraction) defining features:

A
  • wide QRS
  • absent P wave
  • T wave opposite R wave
43
Q

SVT (supraventricular tachycardia) defining features:

A
  • HR > 150
  • narrow QRS
  • indistinguishable P wave (P or T wave?)
  • regular rhythm
44
Q

Junctional Rhythm defining features:

A
  • HR 40-60
  • narrow QRS
  • absent/inverted P wave
45
Q

Bundle Branch Blocks
R BBB V1 QRS Morphology characteristic?
L BBB V1 QRS Morphology characteristic?

A

R BBB: “rabbit ears” or “M” pattern; QRS points up (like a R turn signal)
L BBB: deep wife WRS “W” pattern; QRS points down (like a L turn signal)

46
Q

What is the importance of axis deviation?

What is the normal degrees of axis deviation?

A

wave of depolarization shifts AWAY from infarct and TOWARD area of hypertrophy
-30 to +90

47
Q

Normal Axis Deviation QRS: Lead 1 (+) AVF (+)
Look at lead 1 and AVF (is the QRS positive or negative)
R axis deviation 1: __ AVF: __
L axis deviation 1: __ AVF: __

A

R axis deviation 1: (-) AVF: (+)

L axis deviation: 1: (+) AVF: (-)

PCCN (3 decks)

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