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Clin med exam 2 anatomy exam 1 > EKG I & II > Flashcards

EKG I & II Flashcards

1
Q

In a 3 lead EKG, what does lead I measure?

A

Lead I measures electrical potential between left arm (+) and right arm (-)

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2
Q

In a 3 lead EKG, what does lead II measure?

A

Lead II measures electrical potential between left leg (+) and right arm (-)

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3
Q

In a 3 lead EKG, what does lead III measure?

A

Lead III measures electrical potential between left leg (+) and left arm (-)

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4
Q

What 3 pieces of information can you get from a 3 lead EKG?

A
  • HR
  • Regularity of heart beat
  • Length of conduction in different parts of the heart *May fail to reveal various abnormalities (12 lead EKG is now standard of care)
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5
Q

Name all of the leads included in a 12 lead EKG

A
  • Limb leads I, II, and III
  • Augmented leads aVR, aVL, and aVF
  • Precordial or chest leads V1-V6.
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6
Q

In the X-axis, each small box is ____mm and represents ____sec.

Each large box is 5 small boxes and represents ____sec.

5 large squares equals ____sec.

A

In the X-axis, each small box is 1 mm and represents 0.04 sec.

Each large box is 5 small boxes and represents 0.20 sec.

5 large sqaures equals 1 sec.

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7
Q

In the Y-axis, each small box represents ____mV and each large square represents ____mV

A

In the Y-axis, each small box represents 0.1 mV and each large square represents 0.5 mV.

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8
Q

What is the primary pacemaker of the heart, located in the upper right atrium?

A

Sinoatrial node (SA node).

  • Intrinsic rate 60-100 bpm
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9
Q

This structure slows impulses and backs up the pacemaker (i.e. if SA node stops working), and is located in the lower right atrium. AKA “gatekeeper”

A

Atrioventricular node (AV node)

  • Intrinsic rate 40-60 bpm
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10
Q

Which structure spans from the AV node through the top portion of the ventricular septum and has an intrinsic rate of 20-40 bpm?

A

Bundle of his

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11
Q

The intrinsic rate of the left and right bundle branches is ______bpm

A

20-40 bpm

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12
Q

The intrinsice rate of Purkinje fibers is _____bpm

A

10-30 bpm

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13
Q

What does the P-wave represent?

A
  • Depolarization of atria in response to SA node triggering.
  • A normal P wave means the SA node is properly initiating the beat
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14
Q

What does the PR interval represent?

A
  • Atrial depolarization through the onset of ventricular depolarization (delay of AV node to allow filling of ventricles).
  • Used to measure the regularity of the rhythm (if R-R distance is the same throughout, you have a regular rhythm)
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15
Q

What does the QRS complex represent?

A

Ventricular depolarization - time from the AV node through the Purkinje fibers

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16
Q

What does the ST segment represent?

A

Beginning of ventricle repolarization (the time between ventricular depolarization to repolarization)

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17
Q

What does the T-wave represent?

A

Ventricular repolarization/relaxation

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18
Q

Dimentions of a normal P-wave:

  • Normally (upright/inverted), but may be (upright/inverted) in aVR and V1.
  • Up to _____mm in amplitude
  • Less than _____ sec (or less than _____ small boxes)
A
  • Normally upright, but may be inverted in aVR and V1.
  • Up to 2.5 mm in amplitude
  • Less than 0.12 sec or less than 3 small boxes
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19
Q

What does “sinus” mean?

A

Sinus only means SA node is pacing. It does not necessarily mean nl EKG.

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20
Q

The presence of broad, notched (bifid) P waves in lead II or V1 is a sign of ____________________.

A

The presence of broad, notched (bifid) P waves in lead II or V1 is a sign of left atrial enlargement.

  • Causes: HTN, aortic stenosis, HOCM if seen in combination with LVH
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21
Q

The presence of peaked P waves (high amplitude) in leads II and V1 is indicative of _______________.

A

The presence of peaked P waves (high amplitude) in leads II and V1 is indicative of right atrial enlargement.

  • Causes: pulmonary hypertension, chronic lung disease, TS
22
Q

What are ectopic P waves? Are they upright or inverted?

A
  • Waves that do not originate from the SA node.
  • Upright if coming from high in atria
  • Inverted if coming from lower or from AV node
23
Q
  • How is the PR interval measured?
  • What is the nl duration (sec)?
A
  • Measured from beginning of P wave to onset of QRS complex
  • Normal duration <0.20 sec (1 large box)

***You need to measure multiple PR intervals!!! It can vary and can indicate AV blocks

24
Q
  • How is the QRS complex measured?
A
  • Begins where the first wave complex deviates from baseline and ends where last wave of complex flattens at, above, or below the baseline.
25
Q

What are the normal dimensions of the QRS complex?

A
  • Less than 0.12 sec (3 small boxes)
  • Amplitude varies from <5 mm to >15 mm.
  • If QRS complexes are large enough to touch each other = LVH
26
Q

What are the normal dimensions of a Q wave?

A

Should be less than 2 boxes in amplitude and 1 box in duration

27
Q

What does a pathological Q wave look like and what does it mean?

A

A Q wave can be pathological if it is:

  • Deeper than 2 small squares (0.2 mV) and/or
  • Wider than 1 small square (0.04 s)

It’s ok to not see a QW, but large QW can indicate current MI or prior MI.

28
Q
A

From the end of the QRS complex to the beginning of the T wave.

29
Q

It’s important to determine if the ST segment is elevated or depressed by using the isoelectric line. Greater than ____small boxes may be pathologic. Use the _____ interval as reference to see if ST is elevated or depressed.

A

It’s important to determine if the ST segment is elevated or depressed by using the isoelectric line. Greater than 2 small boxes may be pathologic. Use the PR interval as reference to see if ST is elevated or depressed.

30
Q

What does ST elevation represent?

A
  • Infarction
  • Pericarditis - diffuse elevation in all/most leads
  • Early repolarization
31
Q

What does ST depression represent?

A
  • Ischemia
  • After Digitalis administration (Digitalis is an inotropic medication that helps the heart squeeze harder, used with CHF)
32
Q

What is the J point?

A
  • The point at which the ST segment “takes off” from the QRS complex is called the J point. It represents the end of ventricular depolarization.
  • May not be evident
  • May indicate early repolarization, ischemia/infarction, or pericarditis
33
Q

What can inverted T waves be indicative of?

A
  • Cardiac ischemia
  • Left ventricular hypertrophy
  • CNS injury
  • Digitalis administration
  • Hypokalemia
34
Q

T wave amplitude more than half the height of QRS complex (peaked T waves) may indicate __________ or __________.

A

T wave amplitude more than half the height of QRS complex (peaked T waves) may indicate myocardial ischemia or hyperkalemia

35
Q

How is the QT interval measured?

A

Beginning of QRS complex to end of T wave

36
Q

What does the QT interval represent?

A

Ventricular depolarization and repolarization (how quickly the ventricle contracts and relaxes)

37
Q
  • What is the normal duration of QT interval?
A
  1. 33 sec - 0.47 sec (>0.5 is abnormal!)
    - As a rule of thumb, the QT interval should be half the R-R interval
    - Most EKGs will provide a corrected QT (QTc)
38
Q

Prolonged and shortened QT interval both increase risk of ____________.

A

Prolonged and shortened QT interval both increase risk of ventricular tachycardia - torsades.

39
Q
  • Prolonged QT can be genetic or caused by ________, __________, or ___________.
  • Shortening can be due to __________.
A
  • Prolonged QT can be genetic or caused by medications, hypothyroidism, or hypocalcemia.
  • Shortening can be due to hypercalcemia
40
Q

Where would you see a U wave and what would it represent?

A
  • Thought to represent repolarization of the papillary muscles or Purkinje fibers
  • If present, will follow the T waves (seen more often in young athletes and bradycardia)
  • If large, may represent hypokalemia, thyroid disease, medication effect
41
Q
A
42
Q

What are the two most common ways to calculate rate on the EKG?

A
  • Six-second method (simplest, quickest, andmost commonly used method - used to approximate rate in regular rhythms)
  • Triplicate methods
43
Q

How do you calculate HR using the 6-second method?

A

Count the # of QRS complexes in a 6 second interval and multiply # by 10.

44
Q

How do you calculate HR using the triplicate method?

A
  • Find an R wave that falls on a dark line
  • Count out to the right each dark line as 300, 150, 100, 75, 60, 50 bpm.
  • If irregular rhythm, report as range from smallest to biggest.
45
Q

What can an indeterminate axis represent?

A

Emphysema, hyperkalemia, lead placement

46
Q

What are the steps for EKG interpretation? (acronym)

A

Age of pt

Rate

Axis

Rhythm

Evaluate each EKG element as follows:

P wave (peaked or absent? PR interval short/prolonged?)

Q wave (deep Q wave? QT interval short/prolonged?)

R wave

ST segment (elevation/depression?)

T wave (peaked or inverted? U wave?)

47
Q

What does axis represent?

A
  • Refers to general direction of the heart’s depolarization
  • Should be in the direction of the most muscle in the heart - usually the left ventricle
  • Clinical relevance: hypertrophy, ischemia/infarction, blocks
48
Q

Describe the thumb method of determining axis orientation

A
  • Left thumb is Lead I and right thumb is aVF
  • If QRS is predominantly positive, hold that thumb up, and if negative, down
  • If Lead I and aVF are positive = both thumbs up = normal
  • If Lead I positive and aVF negative = left thumb up, right thumb down = left axis deviation (LAD)
  • If Lead I negative and aVF positive = left thumb down, right thumb up = right axis deviation (RAD)
  • If both Lead I and aVF negative = both thumbs down = indeterminate: (if lead II positive = normal. If lead II negative = LAD)
49
Q

What can a left axis deviation (LAD) represent?

A
  • Left ventricular hypertrophy (LVH)
  • Emphysema
  • Hyperkalemia
  • Atrial septal defect
  • Obesity
50
Q

What can a right axis deviation (RAD) indicate?

A
  • Normal in kids and tall thin adults
  • Right ventricular hypertrophy
  • Chronic lung dz
  • PE
51
Q

What does regularly irregular mean?

A
  • Patterned irregularity or “group beating”
52
Q

What does irregularly irregular mean?

A

Clin med exam 2 anatomy exam 1 (8 decks)

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