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.systems based core clinical specialties > P and QRS waves > Flashcards

P and QRS waves Flashcards

1
Q

Electrocardiogram (ECG)

A

Graphic record of the electrical potentials produced by cardiac myocytes (voltage over time)
Dx arrythmias

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2
Q

Positioning of the ECG

A

Right lateral recumbency
Black: LA, white: RA, red: LL green: RL

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3
Q

Limb leads: frontal plane

A

Lead 1: right arm to left arm
Lead 2: Right arm to left leg
Lead 3: left arm to left leg

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4
Q

Bipolar leads

A

Contain a negative pole (-) and positive pole
Limb leads 1, 2 and 3

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5
Q

Unipolar leads (augmented)

A

Measures the electric potential @ 1 point with respect to null point
Augmented leads aVR, aVL, and aVF

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6
Q

Cardiac conduction system

A
  1. Sinus node (initiation of electrical impulse 60-180 bpm)
  2. AV node (only link between atrium and ventricles 40-60 bpm)
  3. Purkinje fibers (inherent rate of 20-40 bpm)
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7
Q

Rule of ECG

A

Rapid depol/ repol= narrow tracing
Slow depol/ repol = wide tracing

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8
Q

P wave

A

Organized atrial depolarization
absent or sometimes= no atrial depolarizations

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9
Q

What happens when you never see a P wave?

A

Slow regular ventricular complexes
Atrial flutter or fibrillation
Atrial standstill

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10
Q

What happens when you sometimes see a P wave?

A

P with ventricular complexes
Sinus node disease

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11
Q

QRS complex

A

Ventricular depolarization
Q is first - delfection, R is first + deflection
S always second - or first - after + QRS

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12
Q

T wave

A

Ventricular repolarization
T +, -, or biphasic
Each beat MUST have a T wave

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13
Q

Intervals

A

The amount of time it takes for a wave of conduction to propagate through the heart

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14
Q

PR interval

A

Beginning of P to beginning of Q
Atrial depol and conduction through the AV node

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15
Q

QT interval

A

Beginning of Q to the end of T
Ventricular activity

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16
Q

Calculating HR with 25 mm/sec

A

Average: 30 large boxes= 6 sec
Number of complexes x 10
Instantaneous: 1500/ # small boxes between consecutive R waves

17
Q

Calculating HR with 50 mm/sec

A

Average: 30 large boxes= 3 sec
Number of complexes x 10
Instantaneous: 3000/ # small boxes between consecutive R waves

18
Q

When is each method for calculating HR used?

A

Average used to irregular arrhythmias
Instantaneous used to regular rhythms or non-sustained arrhythmias

19
Q

What happens when there ISN’T a P wave for every QRS?

A

Early: premature, late: escape
Ectopic v. sinus beat
Looks similar: supraventricular/ atrial
Looks different: Ventricular

20
Q

Ventricular premature contractions (VPCs)

A

No associated P waves
Earlier than expected sinus beat
QRS of ectopics look different from sinus QRS
premature: wide and bizarre

21
Q

Atrial premature contractions (APCs)

A

No associated P waves
Earlier than the next expected sinus beat
QRS of ectopics look similar to sinus QRS
above the ventricle

22
Q

Ventricular escapes

A

Some sinus, bradycardia
Ectopics have no associated P wave, late
QRSs of ectopics are wide and bizarre

23
Q

Escape beats: safety mechanism

A

Sinus mode:P wave, narrow QRS complex
AV node: No P wave, narrow QRS
Ventricle (purkinje): No P, wide QRS
beats generated by pacemakers when sinus rate becomes too slow or arrests

24
Q

Abnormal P waves

A

P wave + when initiated from sinus node
P wave - from abnorm origin in atrium

25
Q

___________ cells only work as pacemaker if diseased

A

Atrial myocardial cells
abnormal P waves

26
Q

1st degree AV block

A

Prolongation of PR interval (dogs: 0.13, cat: 0.09)
Slow conduction in the AV node

27
Q

What caused 1st degree AV block?

A

Fibrosis in the AV node
↑ vagal tone (physiologic, systemic disease, drugs like betablocks- digoxin)
exception to rule (QRS for every P)

28
Q

2nd degree Type 1 AV block (Wenckebach)

A

Gradual prolongation of the PR interval than dropped P
sometimes no QRS for every P

29
Q

2nd degree Type 2 AV block

A

Some conduction through the AV node
No pattern of PR prolongation
Dropped Ps are random
sometimes no QRS for every P

30
Q

3rd degree AV block

A

Impulse always blocked in AV node (sinus faster than escape rate)
Secondary pacemaker takes over
always no QRS for every P

31
Q

Bundle branches

A

Rapidly propagate the wave of depol through the L and R ventricles

32
Q

Left bundle branch block

A

Right ventricle depol rapidly and normally via the right bundle branch
Left ventricle activated late and slowly making QRS wide and bizarre

33
Q

Left ventricular hypertrophy

A

Sinus rhythm with skinny, tall R waves

34
Q

Right bundle branch block

A

Left ventricle depol rapidly and normally via left bundle branch
Right ventricle activated late and slowly making QRS wide and bizarre

35
Q

Right ventricular hypertrophy

A

Sinus rhythm with skinny, deep S waves

.systems based core clinical specialties (27 decks)

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