Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

ECG > PQRST ECG questions > Flashcards

PQRST ECG questions Flashcards

1
Q

Describe the quadrant method for determining axis deviation

A

Look at lead I and aVF
Examine QRS to determine if positive, isoelectric or negative
A positive QRS in lead I puts the axis in roughly the same direction as lead I
A positive in aVF aligns the axis with aVF
Combine both areas - the quadrants that overlap determine the axis
Add in lead II for greater accuracy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the isoelectric method for axis determination

A

If the QRS is positive in any given lead the axis points in roughly the same direction
If the QRS is negative the the axis is roughly in the opposite direction
If the QRS is isoelectric then the axis is at 90 to this lead

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the usual ECG paper speed?

A

25mm/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How many seconds per small and big squares?

A 
1mm = 0.04 secs (small square)
5mm = 0.2 secs (big square)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How do you estimate rate on an ECG - 3 methods

A
  1. 300/number of large squares R-R
  2. 1500/small squares R-R (useful for very fast heart rates)
  3. Number of complexes on rhythm strip x 6 (= average rate over 10 sec period)(useful in slow or irreg ECGs)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a u wave?

A

Small (0.5mm) deflection immediately following the T wave
- usually in the same direction as the T wave
- best seen in V2+V3
- Gets bigger with slower heart rates
Prominent or inverted U waves are abnormal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What causes prominent U waves?

A 
Hypocalcaemia
Hypomagnesaemia
Hypothermia
Raised ICP
LVH
Hypertrophic cardiomyopathy
Digoxin
Phenothiazines
Class Ia and II antiarrythmogenics
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What causes inverted U waves?

A 
CAD
HTN
Valvular heart disease
Cardiomyopathy
Hyperthyroidism
Congenital heart disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the PR interval

A

Time from onset of P wave to start of QRS
Reflects conduction through the AV node
Normally 120-200ms (3-5 small squares)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the abnormalities of the PR interval

A

1st degree heart block - Prolonged PR
2nd degree heart block
- Mobitz type 1: successive prolongation until a QRS in dropped (Wenkebach)
- Mobitz type 2: intermittent non-conducted p wave (no successive prolongation)
Short PR interval occurs in pre-excitation syndromes and AV nodal (junctional) rhythms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the PR segment?

A

The flat, usually isoelectric segment between the end of the p wave and the start of the QRS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the abnormalities that can occur with the PR segment

A

Pericarditis: PR segment depression, wide-spread ‘saddle-shaped’ ST elevation, reciprocal ST depression and PR elevation in aVR and V1
Atrial ischaemia: PR segment elevation or depression in patients with MI indicates concomitant atrial ischaemia or infarction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the QT interval?

A

The time from the start of the Q until the end of the T wave
Represents time for ventricular depolarisation and repolarisation
Inversely proportional to hr

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How do you calculate QTc?

A

QT divided by thr square root of RR (in seconds = 60/hr)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

When is QTc prolonged?

A

> 440ms men
460ms women
500ms is associated with an increased risk of torsades

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What causes prolonged QTC?

A 
Hypokalaemia
Hypomagnesaemia
Hypocalcaemia
Hypothermia
Myocardial ischaemia
Post-cardiac arrest
Raised ICP
Congenital
Drugs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What causes QTC < 350ms?

A

Hypercalcaemia
Congenital
Digoxin

18
Q

What is the ST segment?

A

The flat, isoelectric section between the end of the s wave (j point) and the beginning of the T wave
Represents the interval between ventricular depolarisation and repolarisation

19
Q

What causes ST elevation?

A 
AMI
Printzmetals angina
Pericarditis
Benign early repolarisation
LBBB
LVH
Ventricular aneurysm
Brugada syndrome
Ventricular paced rhythm
Raised ICP
20
Q

Which leads are septal?

A

V1-2

21
Q

Which leads are anterior?

A

V3-4

22
Q

Which leads are lateral?

A

I, aVL, V5-6

23
Q

Which leads are inferior?

A

II, III, aVF

24
Q

Which leads are RV

A

V1, V4R

25
Q

Which leads are posterior?

A

V7-9

26
Q

What causes ST depression

A 
Ischaemia
NSTEMI
Post MI
Digoxin (reverse tick)
Hypokalaemia
SVT
RBBB
LBBB
LVH
Paced rhythm
27
Q

What is the width of a normal QRS complex?

A

Normally 70-100ms
< 100ms are supraventriclaur in origin - SA, atria, AVN
>100 are either ventricualr or due to abberant conduction

28
Q

What causes broad QRS complexes?

A 
BBB (>120ms needed for diagnosis)
Hyperkalaemia
TCA OD
WPW
Paced rhythm
Hypothermia
29
Q

What causes QRS of altering height?

A

Normally due to a massive pericardial effusion

30
Q

What does a T wave represent?

A

Ventricaular repolarisation

31
Q

What are the characteristics of a normal T wave?

A

Upright except aVR and V1

Amplitutde < 5m in limb leads and < 15mm precordial leads

32
Q

What causes T wave abnormalities

A

Hyperkalaemia - peaked
Hyperacute - STEMI
Inverted - MI, ischaemia, normal in kids, BBB, ventricular hypertrophy, PE, hypertrophic cardiomyopathy, raised ICP
Biphasic - myocardial ischaemia (T waves go up the down), hypokalaemia (T waves go down then up), Wellen’s syndrome

33
Q

Where on the ECG axis are each of the leads?

A 
O - I
\+60 - II
\+90 - aVF
\+120 - III
-150 - aVR
-30 aVL
34
Q

What is an r wave?

A

The first upward deflection after the P wave

It represents early ventricular depolarisation

35
Q

What are the 3 key abnormalities that occur with the r wave?

A
  1. Dominant R in V1 - RVH, RBBB, post MI, WPW type A, incorrect lead placement, dextrocardia, hypertrophic cardiomyopathy, normal in kids and young adults
  2. Dominant R in aVR - sodium channel blocking drug toxicity, dextrocardia, incorrect lead placement, VT
  3. Poor R wave progression - R wvae < 3mm in V3 due to anteroseptal MI, LVH, inaccurate lead placement, may be normal
36
Q

What is a Q wave?

A

Any negative deflection that precedes and R wave
Represents normal L-R depolarisation of the IV septum
Small septal Q waves typically seen in left sided leads

37
Q

When is a Q wave pathological?

A 
>40ms (1mm wide)
> 2mm deep
> 25% of depth of the QRS complex
Seen in leads V1-3
May indicate current or prior MI
38
Q

Describe a normal p wave?

A

normally smooth, monophasic, should be upright in I, II and inverted in aVR
< 120ms
amplitutde: <2,5mm in limb leads, < 1,5 in precordial leads

39
Q

What happens to p waves in right atrial enlargement?

A

lead II - p waves taller

40
Q

What happens to p waves in left atrial enlargement>?

A

lead II - duration > 120ms

41
Q

What are the common abnormalities of p waves?

A

p mitrale - LAE classically due to mitral stenosis
p pulmonale - RAE usually due to pulmonary hypertension
Inverted - non-sinus in origin
Variable morphology - multifocal atrial rhythm

ECG (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions