Arrhythmias Flashcards

1
Q

Formula for cardiac output?

A

CO = SV * HR

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

What does stroke volume depend on?

A

SV depends on

1) IN - efficient diastolic filling
2) OUT - efficient heart pumping

at extremes:

tachycardia is a problem of efficient filling (too little t)

same is also true for premature beats - not enough time for ventricles to fully fill

bradycardia is a problem of efficient pumping (too slow)

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

What does P wave, QRS complex and T wave stand for?

A

P wave = atrial depolarization (activation)

QRS = ventricular depolarization (activation)

T wave = ventricular repolarization (relaxation)

* QT interval = important on wards for one condition - prolonged QT interval (by drugs, genetics), potential for lethal arrhythmias*

* ST segment - between S and T wave, especially important for MIs and ischemia*

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

Define PR, QRS and ST intervals?

A

PR - from start of P to start of QRS

PR < 0.2 s (under 5 blocks)

QRS < 0. 1 s (under 2.5 blocks), if < 0.12 s - some widening, if >0.12 s - severe widening, blockage in ventricle (bundle branch block!)

ST - from end to QRS to end of T wave

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

One more time, lets go through the whole piece of ECG!

A

Nothing is nothing, it is diastolic filling, if the time is short, there is trouble - CO effect!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a rhythm strip?

A

usually lead II along bottom (b/c it mimics direction of electric flow best)

start each ECG analysis by looking at rhythm strip

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

Approach to ECG readin’?

A

1. Rate (300-150-100-75-60-50 rule)

60-100 normal

>100 tachycardia

<60 bradycardia

or count a number of big squares btwn each QRS and divide 300 by # of squares. if 3 boxes, 100 bpm

**2. Rhythm **

  • regular
  • regular with extra random beats
  • irregular with pattern
  • irregular without pattern

3. P wave - atrial activation, priming ventricular pump

Present? Same shape and size? more of fewer than QRS complexes? relationship btwn the P wave and QRS complexes?

PR 0.12-0.2 (3-5 boxes)

**4. QRS **

normal is <= 3 squares = 0.12 seconds

wider - conduction delay, like bundle branch blocks, ectopic beats (conducted through myocardium and not conducting system, so takes longer), toxic drugs…

5. T wave

ALSO Pacemaker location

determine the location of the pacemaker:

SA, atria, AV, ventricles

and direction: does atrium activate ventricle, etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Cool mnemonic for ECG approach?

A

A RARE PQRST

DR III EEE

Age, e.g. a 60-yo patient is likely have a different pathology from a 30-yo patient
Rate, e.g. fast or slow?
Axis, e.g. left or right?
Rhythm, e.g. regular or irregular?
Evaluate each EKG element as follows:
P wave, e.g. peaked or absent? PR interval - short or prolonged?
Q wave, e.g. deep Q wave? QT inerval - - short or prolonged?
R wave, e.g. tall? look at QRS complex width for RBBB or LBBB
ST segment, e.g. elevation or depression?
T wave, e.g. peaked or inverted? U wave?

DR III EEE:

Drugs , e.g. Digoxin, tricyclic antidepressants
Rhythm and rate abnormalities, e.g. AV block of 1,2,3 degree, AFib, SVT? Interval prolongation?

  • *Ischemia?**
  • *Infarct? Deep Q wave?**
  • *Infection, e.g. pericarditis**
  • *Enlargement,** e.g. LVH, RVH, left or right atrium enlargement?
  • *Electrolyte disturbances**, e.g. hyperkalemia, hypokalemia, hypercalcemia,
  • *Endocrine causes**, e.g. hypothyroidism

How to use this approach in practice?

Look at the EKG and write down on a piece of paper:

A R A R E P Q R S T
D R I I I E E E

Circle the abnormalities you discover in step 1 – A RARE PQRST. Then, connect and try to explain these abnormalities by looking at the list of possible etiologies presented in step 2 – DR III EEE. That’s it!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the maximum HRs for different pacemakers (SA, atria, AV, ventricle)?

A

SA- maximum physiological HR is 220-age

therefore if HR>200, SA as pacemaker unlikely

P waves present, since travels to AV ->…

short PR interval unlikely, since signal starts normally and has to travel through all the stops (atria, AV, Bundle of his…); P wave followed by QRS

Atria - refractory period, HR > 200 unlikely to be in atria

atrial pacemakers have to conduct through the rest of the atria, so they do generate P wave, but it would be a different shape, as atrial pacemaker will be located in a different location from SA node

atrial fibrillation - irregular chaotic rhythm, no pattern, no P waves

atrial flutter - sawtooth

AV node - slow heart rate (normal 45-50), but can generate faster heart rate if part of re-entry circuit

AV node does not have the normal refractory period of SA, so if part of re-entry, can generate > 200 bpm

P wave timing will depend on how far in the AV node the pacemaker is - near the top - very short PR interval, then QRS, near the bottom - P after QRS

P usually inverted (upside down) because traveling in opposite direction

Ventricles - QRS will be wide because signal would travel slowly

No P wave that goes up to atria, QRS alone is hard,

sometimes there might be something in atria generating P, so P and QRS dissociated completely

shorter refractory periods than in atria, > 200 bpm possible

=> > 200 bpm usually exclude atria and SA

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

What does an ECG with pacemaker look like?

A

the first spike before QRS is called a pacing spike - it generates an electrical signal to cause ventricle to contract

pacing spike tells you where pacemaker is located - if before P wave - in atrium, if before QRS and T wave - in ventricle

we pace people normally when heart is too slow, sometimes can also rapidly pace someone out of tachycardias

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

How would you treat?

A

A:

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