electrocardiomyography 2

Question 1

where does a supraventricular arrhythmia start

Answer 1

abvove the SAN

Question 2

where does a junctional arrhythmia start

Answer 2

in the AVN or bundle branches

Question 3

where does a ventricular arrhythmia start

Answer 3

in the ventricle muscle itself

Question 4

what 3 things can a ECG detect

Answer 4

conduction abnormalities
structural abnormalities
perfusion abnormalities

Question 5

how can you see electrical abnormalities

Answer 5

measuring electrical conduction

Question 6

how can we see the structural abnormality left ventricular hypotrophy

Answer 6

increase in muscle in L wall - reduce vol
left ventricle to base
L axis deviation
(can tell it is L axis deviation because the axis is deviate clockwise)

Question 7

what is cardiac axis

Answer 7

the net direction of cardiac depolarisation

Question 8

how can you tell if there are perfusion abnormalities, ie a blockage in the coronary artery

Answer 8

the tissue is ischemic so cannot contract,

Question 9

endocardium

Answer 9

inside of the heart

Question 10

myocardium

Answer 10

muscle

Question 11

epicardium

Answer 11

outside of the heart

Question 12

what are the 4 things you do before reading the ECG

Answer 12

check it is the correct recording ie the name
review the signal quality (can be changed by muscular movement, controlled by signals from the brain) and the leads - ie 12 leads, check not noisy
verify the voltage and the paper speeds (paper speed = 25ml/s, V= 10ml/mvol
review the patient and background info - will help to explain things

Question 13

steps when looking at an ECG

Answer 13

1. rate and rhythm - gap between r waves regular, or is rate irregular on rhythm strip, 60-100bpm normal rate
2. check the p wave and PR interval - how long takes for wave of depolarisation to go through the atrial myocardium and AVN (meant to impede)
3. QRS duration - 160, broad/narrow
4. QRS axis
5. ST segment - isoelectric, look at height
6. QT interval
7. T wave - tall and tented/small aand narrow- can see electrolyte disturbance and repolarisation of the heart beat.

Question 14

characteristics of a sinus rhythm

Answer 14

1:1 ratio of P:QRS - P always followed by QRS
rate regular and normal
otherwise unremarkable

Question 15

how do you calculate a rate from an ECG

Answer 15

calculate the average number of little squares * 0.04

ANS/60 = rate

Question 16

what is bradycardia

Answer 16

slow heart

Question 17

characteristics of sinus bradycardia

Answer 17

1:1 ratio
rate regular
rate slow
can be healthy - just have bigger heart, mediatation, extra vagal (ie PNS stimulation)

Question 18

quick way to calculate the rate

Answer 18

300/number of big squares

Question 19

what is tachycardia

Answer 19

fast heart

Question 20

characteristics of tachycardia

Answer 20

1:1 
rate regular 
rate fast 
not healthy 
but it is physiological eg response to overactive adrenal gland/SNS, or SV lower than it should be because of a smaller venous return

Question 21

why is resting heart rate difficult to measure

Answer 21

always going to be some excitation

in sleep - underestimate

Question 22

how can you tell axis deviation from an ECG

Answer 22

L axis deviation = L1 +ve, L3 -ve both leaving the paper

R axis deviation = L1 -ve and L3 +ve - both entering the paper

Question 23

characteristics of sinus arrhythmia

Answer 23

1:1
irregular rate - variable R-R intervals
reading depends on where it is taken
varies with breathing cycle

Question 24

characteristics of atrial fibrillation

Answer 24

oscillating baseline - atria contract asynchronously
rhythm irregular
rate may be slow
turbulent flow = blood sitting and not circulating = increased clot risk
atria not essential for the cardiac cycle - passive filling does most of it, only important in terms of contraction
QRS normal
T wave present - less obvious because smaller and baseline oscillates

Question 25

characteristics of atrial flutter

Answer 25

regular sawtooth pattern in baseline in leads 2, 3 and aVF 2:1 or 3:1 or higher not always visible in all leads T wave can be obscured or have similar morphology to the P waves has a vector because regular pattern duration of the P wave is the same

Question 26

characteristics of the 1st degree block

Answer 26

``` prolonged PR segment - slower AV conduction regular rhythm 1:1 benign but progressive disease of aging QRST fine AV valve healthy so no backflow V still contract normally ```

Question 27

characteristics of a 2nd degree heart block - Mobitz 1

Answer 27

gradual prolonged PR, until beat is skipped most P waves followed by QRS, some not regularly irregular - caused by diseased AVN also called Wencebach each part is independently regular

Question 28

characteristics of a 2nbd degree heart block - Mobitz 2

Answer 28

p wave regular - only some followd by QRS no P-R prolongation regularly irregular eg successes: failures 2:1 can rapidly deteriorate into 3rd degree heart block detected by patient as palpitations

Question 29

characteristics of 3rd degree heart block

Answer 29

complete P waves regular, QRS regular - no relationship P waves can be hidden in bigger vectors non-sinus ie no pacemaker pacemaker intrinsic setting at 75bpm AVN 50bpm ventricular myocardium- 30bpm normally because SAN is the highest rate it controls everything here ventricles act independently looks like P waves are moving L because they are less frequent than QRS

Question 30

characteristics of ventricular tachycardia

Answer 30

P waves hidden, dissociated atrial rhythm V fast and coordinated need it to be coordinated - other wise it contracts faster than it can fill rate regular and fast high risk of deteriorating into fibrillation shockable rhythm regular vectors

Question 31

characteristics of ventricular fibrillation

Answer 31

``` unable to talk - brain getting no oxygen HR .250bpm heart unable to generate an output shockable rhythm no filling irregular ```

Question 32

characterisitics of ST elevation

Answer 32

``` any deviation- blood flow problem regular rhythm and normal rate P wave visible 1:1 ST segment elevated >2mm above isoelectric line caused by infarction ```

Question 33

characteristics of ST depression

Answer 33

regular rhythm and normal rate P wave visible 1:1 ST segment depressed >2mm below isometric line caused by myocardial ischemia - coronary arties cannot supply the myocardium with enough O2