Systematic ECG Analysis

Question 1

what are the four methods of measuring HR on an ECG?

Answer 1

1) Six Second Method
2) Sequence Method
3) Small Square Method
4) Ruler Method

Question 2

what is the 6 second method?

Answer 2

of QRS complexes or P waves in a 6 second period x 10 = bpm

Question 3

what is the sequence method?

Answer 3

choose R wave that falls on a dark line, number the next 6 dark vertical lines on the paper 300, 150, 100, 75, 60, 50.

Question 4

what is the small square method?

Answer 4

count # of small boxes between P or R waves, divide by 1500 = bpm

Question 5

what is the ruler method?

Answer 5

use ECG ruler. place 0 at top of R wave, count 3 waves over from first = bpm

Question 6

what does it mean if a rhythm strip has no P waves?

Answer 6

no atrial depolarization = no contraction = no atrial kick = loss of 15-30% of preload = decreased CO

Question 7

what does ST depression or elevation mean?

Answer 7

ST depression = myocardial ischemia
ST elevation = myocardial injury or infarction

Question 8

how do you determine ST elevation or depression?

Answer 8

1) identify isoelectric line
2) identify J point
3) measure 0.06 seconds (1.5 boxes) to the right of the J point
4) if ST segment is above isoelectric line, it is considered elevated and vice versa

Question 9

what is considered significant for ST elevation/depression?

Answer 9

> 1mm (1 small box) from isoelectric line

Question 10

why does the QT interval vary with HR?

Answer 10

high HR shortens QT interval, low HR lengthens QT interval

Question 11

QTc

Answer 11

QT interval corrected for HR

Question 12

what could occur if the QT interval lengthens?

Answer 12

life threatening dysrhythmias, as the relative refractory period is lengthening therefore increasing the time where a cell is vulnerable to a strong stimulus

Question 13

what must you do when stating the rhythm?

Answer 13

state the underlying rhythm with all elements
ie) regular sinus rhythm with PVCs

Question 14

what do you state when you identify the site of impulse formation?

Answer 14

1) what pacemaker site is responsible for the ECG rhythm? SA node, atrial tissue, junctional tissue, ventricles. or a combo.

2) what is the rate of the ECG rhythm, too fast or too slow?

Question 15

what are implications for O2 supply and demand and CO if the ventricular rate is TOO SLOW

Answer 15

potential for decrease in CO d/t slow rate.

Question 16

what are implications for O2 supply and demand and CO if the ventricular rate is TOO FAST

Answer 16

• decrease in VFT = decrease in preload and CO
• decrease in coronary artery perfusion w/ potential for myocardial ischemia (coronary arteries fill during diastole, so if heart is always in systole, arteries will have inadequate time to perfuse)
• increase in myocardial O2 demand with potential for myocardial ischemia if O2 supply is not adequate

Question 17

what are implications for O2 supply and demand and CO if there is NO P WAVE

Answer 17

loss of atrial kick = decreased preload and CO

Question 18

what are implications for O2 supply and demand and CO if there are ST CHANGES

Answer 18

myocardial ischemia/injury and potential for decrease in contractility, leading to decrease in CO

Question 19

interventions

Answer 19

• HR too slow: speed it up using drugs or pacemaker
• HR too fast: slow it down using drugs or electrical conversion
• no P wave: chemically or electrically convert rhythm
• ST changes: minimize/prevent ischemia and injury to myocardium (MONA, cath lab)

Question 20

what are the 13 steps of analyzing an ECG strip?

Answer 20

1) HR
2) rhythm
3) P wave
4) PR interval
5) QRS complex
6) ST segment
7) T wave
8) QT interval
9) identify rhythm
10) site of impulse formation/conduction problem
11) causes
12) implications for O2 supply and demand
13) interventions