Md2 Block2 Ecg How To Read

Front 1

#1

Back 1

Determining the Rhythm

rhythm is either sinus rhythm or not sinus rhythm.

(SA node). lead II

Hint 1

P wave before every QRS complex
upright
normal morphology,

NSR
>100, then “sinus tachycardia”
< 60, then “sinus bradycardia”

Front 2

#2

Back 2

no P waves present or the P wave morphology abnormal

-rhythm must be determined
-different arrhythmias exist and include

Hint 2

atrial fibrillation,
atrial flutter,
ectopic atrial rhythms, junctional rhythms

ventricular rhythms =
ventricular tachycardia
ventricular fibrillation.

Front 3

what dysfctn occurs when
sinus rhythm is still said to be present.

Back 3

Note that when “AV dissociation” is present as previously described (complete heart block or ventricular tachycardia),
there may not be a P wave before every QRS complex, however as long as the P wave is upright in lead II, sinus rhythm is still said to be present.

Front 4

LAD

Back 4

left axis deviation

right axis deviation =

Can P wave or T wave axis
be measured/

Hint 4

RAD

Yes

Front 5

To determine the QRS axis, the ____ leads need to be examined

Back 5

limb
(not the precordial leads).

Hint 5

Front 6

Lead Vectors

I
II
II
AVL
AVF
AVR

Back 6

I = 0
II = +60
III = +120
AVL = -30
AVF = +90
AVR = -150

Hint 6

Front 7

normal QRS axis

Left axis deviation

Right axis deviation

Back 7

- 30 and +90 degrees.

-30 and -90

+90 and +180

Indeterminate axis is between

Hint 7

+/- 180 and -90 degrees.
NW = northwest axis or indeterminate axis

Front 8

The fastest, non-specific method to determine the QRS axis is to find the major direction of the QRS complex (positive or negative) in leads

Back 8

I
aVF.

Front 9

If the QRS complex is upright (positive) in both lead I and lead aVF, then the axis is

Back 9

normal

Front 10

If the QRS is upright in lead I and downward (negative) in lead aVF, then the axis is between

Back 10

0 and -90 degrees,

likely ____ axis deviation.

However, the axis could fall between 0 and -30 which is technically a _____ QRS axis.

To further distinguish normal from left axis deviation in this setting, look at ______ If it is downward (negative), then the axis is more towards -90 and left axis deviation is present.

Hint 10

left

normal
lead II.

If the QRS complex in lead II is upright (positive), then the axis is more towards 0 degrees and the QRS axis is normal.

Front 11

If the QRS is predominantly _______ in both leads I and aVF, then the axis is indeterminate.

Back 11

downward


If the QRS is downward (negative) in lead I and upward (positive) in lead aVF, then the axis is _________.

Hint 11

rightward

Front 12

SA node, the physiological pacemaker. This electrical impulse is propagated throughout the right atrium, and through ____ _____ to the left atrium, stimulating the myocardium of the atria to contract.

Back 12

Bachmann's bundle

As the electrical activity is spreading throughout the atria, it travels via specialized pathways, known as__ ____ from the SA node to the AV node.

Hint 12

internodal tracts,

Front 13

Atrial enlargements can =
2ct

Back 13

widen the P wave or increase the P wave amplitude.

Front 14

PR interval. This represents the time that it takes for the electrical impulse generated in the

Back 14

sinus node to travel through the atria and across the AV node to the ventricles.

Front 15

normal PR interval is =
or
milliseconds (ms). =

Back 15

0.12 to 0.20 seconds

120 to 200

Some refer to the PR interval as the PQ interval which can be confusing.

Hint 15

If no Q wave is present, then the interal is measured from P to R. If no R wave is present, the interval is measured from P to Q.

Front 16

Multiple abnormalities of the PR interval can occur including =

Back 16

prolongation,
shortening
variation from beat to beat.

Front 17

A prolonged PR interval indicates delayed conduction of the

Back 17

SA nodal impulse
to the ventricles and is called

A short PR interval can be seen then the AV node delay is bypassed such as in =

The PR interval will vary in =

Hint 17

1st degree AV block.

Wolff-Parkinson-White syndrome or
Lown-Ganong-Levine syndrome.

second degree type I AV block (Wenckebach).

Front 18

PR segement is the area beteween the P wave and the onset of the QRS complex. This is supposed to be isoelectric similar to all segments.

PR segment elevation can be seen in lead ___ due to .

Back 18

aVR

pericarditis

The PR segment is not commonly referred to since the above mentioned conditions are relatively rare.

Hint 18

Abnormalities of the Q waves are mostly indicative of myocardial infarctions and are discussed in the ECG criteria review sections. The terms Q wave myocardial infarction and non-Q wave myocardial infarction are old designations of different types of myocardial infarctions where the end result is Q wave development or the absence of Q wave development respectively.

Front 19

R wave morphology itself is not of great clinical importance, however at times it can vary.

Back 19

In lead V1 the R wave is usually quite small, however if the R wave is large in V1 (greater in amplitude than the S wave), then significant pathology may be present

Hint 19

Causes of an R wave to S wave ratio of greater than 1 in lead V1 include a right bundle branch block, Wolff-Parkinson-White syndrome, an acute posterior myocardial infarction, right ventricular hypertrophy and isolated posterior wall hypertrophy (which can occur in Duchenne's muscular dystrophy).

Front 20

In the setting of a right bundle branch block there may be two ____ -____ present giving the classic _________ ____ appearance of the QRS complex. In this setting, the second R wave is termed =

Back 20

R waves

“bunny ear”

R1
R’
“R prime”

Front 21

A large slurred S wave is seen in lead I and V6 in the setting of a =

Back 21

right bundle branch block.

Front 22

In the normal ECG, there is a large S wave in ____ which progressively becomes _____ to the point where almost no S wave is present in ___

Back 22

V1

smaller

V6.

Front 23

The normal duration (interval) of the QRS complex is=

When the duration is between _______ ______ seconds it is intermediate or slightly prolonged.

Back 23

0.08 and .10 seconds
(80 and 100 ms).

0.10 and 0.12

A QRS duration of greater than ____ seconds is considered abnormal

Hint 23

0.12

Front 24

A widened QRS duration occurs in the setting of a

Back 24

right BBB
left BBB
non-specific intraventricular conduction delay
ventricular arrhythmias ie:
ventricular tachycardia

Front 25

T waves should be upright in most leads (except =

Back 25

aVR
V1

T waves should be asymmetric in nature.
The second portion of the T wave should have a steeper decline when compared to the incline of the first part of the T wave.

If the T wave appears symmetric, cardiac pathology may be present such as _____ . Many abnormal T wave patterns exist .

Hint 25

ischemia

Front 26

normal QT interval
QT interval is less than ______
Females have a ____ QT interval than males.

Back 26

400-440 ms
(0.4 to 0.44 seconds).

longer

Also, lower heart rates result in a _______ QT interval.

Hint 26

longer

info
Due to the heart rates effects, the corrected QT interval (QTc) is frequently used. Slower heart rates normally have longer QT intervals and the opposite is true as well. The QTc corrects for this normal variation of the QT interval with heart rate by incorperating the RR interval (which depends on the ventricular rate).

The QTc is considered prolonged if greater than 450 ms in males and 470 in females and is calculated using the Bazett’s formula as below:

Front 27

The ST segment is the portion of the ECG from the =

Back 27

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

The ST segment normally remains isoelectric and thus ST segment depression or ST segment elevation can indicate cardiac pathology.

Front 28

TP Segment

The portion of the ECG from the end of the

Back 28

T wave to the beginning of the P wave.

info

Hint 28

This segment should always be at baseline and is used as a reference to see if the ST segment is elevated or depressed since there are no specific disease conditions which elevate or depress the TP segment.

During states of tachycardia the TP segment is shortened and may be difficult to visualize altogether. It is good to examine the TP segment closely for the presence of U waves or atrial activity that could indicate pathology.