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Cardiopulmonary > 12 Lead ECG > Flashcards

12 Lead ECG Flashcards

1
Q

What are the three types of cardiac cells?

A

-pacemaker: have automaticity
-conducting
-myocardial

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2
Q

What are the specialized nodes and cells in the heart? An where are the nodes located?

A

-SA node (upper part of RA)
-AV node (triangle of Koch)
-bundle of his (AV fibers)
-purkinje fibers

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3
Q

What are the intrinsic rates of SA, AV, and purkinje fibers?

A

SA: 80-100
AV: 40-60
P: 20-40

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4
Q

What is the amplitude and duration of a normal P wave?

A

0.5-2.5mm amplitude and 0.11 sec (3mm)

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5
Q

What does the PR interval represent? And what is a normal interval?

A

Time for electrical activity to move b/w the atria to the ventricles. Normally 0.12-0.2 sec (3-5mm).

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6
Q

What does the ST segment represent?

A

Isoelectric line representing the time b/w ventricle depol and repol.

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7
Q

What does ST segment depression imply?

A

Myocardial ischemia

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8
Q

What does ST segment elevation imply?

A

Myocardial infarct

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9
Q

What does the QT interval represent? And how long is it normally?

A

Represents the time for ventricles to depol and then repol. Normally <0.4 sec (10 small boxes or 2 large boxes). It is usually less than half of one R-R interval.

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10
Q

What is the ECG paper speed?

A

25mm/sec

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11
Q

What is the difference b/w an ECG electrode and an ECG lead?

A

Electrode: conductive pad attached to skin to record electrical activity
Lead: graphical representation of the heart’s electrical activity using several electrodes

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12
Q

What does the QRS axis reflect? Where does the QRS axis normally lie?

A

Reflects the general direction of electrical flow during depol. Usually lies left and downward (-30 and +90 degrees)

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13
Q

How does ventricular mass effect axis deviation?

A

More mass means more intense electrical activity (more to depol).

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14
Q

What factors cause right axis deviation?

A

-normal in the young and thin
-myocardial infarction
-anything that causes RV hypertrophy or stress (ex. severe COPD, PE)

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15
Q

What ECG changes might be seen with right axis deviation?

A

-P waves larger due to RA enlargement in leads II, III and aVF

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16
Q

What factors cause left axis deviation?

A

-may be normal in the older and obese (increased afterload)
-myocardial infarction
-dextrocardia
-high diaphragm (pregnancy, acites)

17
Q

Where is the J point?

A

Right after the QRS wave

18
Q

What is myocardial ischemia indicated by?

A

-depressed ST segment greater than 1mm below baseline at the J point in 2 or more contiguous leads
-hyperacute inversion of T waves

19
Q

Where are the V1-V6 electrodes placed?

A

V1: fourth intercostal space on right sternum
V2: fourth intercostal space on left sternum
V3: midway b/w V2 and V4
V4: fifth intercostal space at midclavicular line
V5: anterior axillary line on same horizontal level as V4
V6: mid axillary line on same level of 4 and 5

20
Q

What changes are seen on ECG if there is myocardial injury?

A

-ST segment elevated greater than 1mm above the baseline at 0.4sec past the J point
-ST segment returns to baseline with restored perfusion–> injury may be reversible

21
Q

What changes are seen on ECG when there is myocardial infarction (necrosis)?

A

-ST elevation
-pathological Q waves appear if old MI present (abnormal if they are greater than 0.4 sec wide and greater than 25% the height of R wave, appear hours to days following acute MI, generally remain for the duration of the pts life)

22
Q

What is the primary criteria for a BBB?

A

Wide QRS (greater than 0.12 sec) for a complete block.

23
Q

What chest leads are used to look at most commonly for BBB?

A

Right: V1 and V2
Left: V5 and V6 (V1 can also tell info on LBBB)

24
Q

What medical conditions can affect the R heart and are screening for with RBBB?

A

-PE
-chronic lung dx
-septal disorders

25
Q

What is the diagnostic criteria for RBBB?

A

-wide QRS
-primary disturbance is an rSR’ wave in V1 or V2
-may have a wide S wave in leads I and V6

26
Q

What pathologies do a LBBB usually indicate?

A

-cardiomyopathy
-hypertension
-CAD

27
Q

What is the diagnostic criteria for a LBBB?

A

-wide QRS
-broad rS or QS wave in lead V1
-broad monomorphic R waves in leads V5, V6 or I (size of LV increases depol time= broader and less defined complexes)
-r,R’ may appear as flattened peak rather than notched
-ST segment depression or elevation

28
Q

What does the p wave look like when there is RA enlargment?

A

-initial upstroke is greater than 2.5mm tall and peaked
-normal duration (less than 0.11 sec)
-seen in leads II, III, aVF, sometimes V1

29
Q

What does the p wave look like with LA enlargment?

A

-p wave greater than 0.12 sec and sometimes notched in limb leads
-could appear biphasic in V1, but predominantly negative or completely negative (takes longer to depol due to increased LA pr and/or volume overload)

30
Q

What are 2 causes of RA enlargement?

A

-COPD
-RV failure

31
Q

What are 3 causes of LA enlargement?

A

-mitral regurge or stenosis
-LV failure
-systemic hypertension

32
Q

What ECG changes are seen with ventricular enlargment?

A

-increased QRS amplitude
-ST depression or elevation
-asymmetrical T wave inversion

33
Q

What ECG changes indicate a RV enlargment?

A

-right axis deviation
-R wave progression in chest leads is reversed (tall R waves in V1-V3)
-deep S waves in leads I, aVL, V5 and V6

34
Q

What ECG changes indicate LV enlargement?

A

-not as obvious are RVH
-increase in QRS amplitude and duration
-taller R waves in I, aVL, V5, V6
-deeper S waves in V1 and V2
-may also see left axis deviation

35
Q

Does an ECG measure pumping ability of the heart?

A

No- it measures electrical conduction.

Cardiopulmonary (4 decks)

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