EKG

Question 0

P wave normal dimensions

Answer 0

Atrial depolarization

Amplitude : .05-.25 (.5-2.5) tiny boxes
Duration: .06-.11 sec (1.5-2.75) small boxes.

Question 1

EKG paper

Answer 1

5 small boxes : 1 sec
1 small box : .2 sec
1 tiny box: .04

1 small box up: .5 mv
1 tiny box: .1

Question 2

P-wave questions

Answer 2

Are they present?

Do they occur regularly?

Is there a P wave for every QRS?

Are P waves smooth, rounded, and upright?

Do all P waves have similar shapes?

Question 3

PR interval normal

Answer 3

.12 - .20 sec (3-5 tiny boxes)

Questions

Does PR interval falls within the norm?
Is it constant across paper?

Question 4

QRS complex norms

Answer 4

.06-.12 (1.5-3 boxes)

Question

Fall within range?
Are they similar in appearance across ECG

Question 5

T waves

Answer 5

Repolarization of Ventricle.

Note downward (negative deflection) or tall pointed peaks

Question 6

QT interval

Answer 6

.36-.44 sec (9-11 tiny boxes)

Less than half R-R interval in HR below 100

Question 7

The 8 steps

Answer 7

1- Rythm
2- Rate
3- P wave
4- PR interval
5- QRS interval
6- T wave
7- QT interval
8- ST segment

Question 8

Rhythm

Answer 8

For ventricular rhythm, examine the R to R intervals on the EKG strip. Calipers or paper marks can be used to fix the distance for one R-R interval and then this distance can be compared to other R-R pairs.

Are they regular, meaning that each heart beat’s R-R interval is equal? Small variations of up to 10% are considered equal. Is the rhythm regularly irregular? For example is there a pattern, such as increasing R-R durations? Or perhaps groups of similar intervals as illustrated on the right? Or are R-R intervals completely irregular?

For atrial rhythm, observe the P-P intervals. Are they regular (minor variations can be caused by the breath cycle)? If P-P intervals are irregular, is there a pattern?

Question 9

Heart Rate

Answer 9

There are several methods for determining heart rate. Our first method is simple. Count the number of QRS complexes over a 6 second interval. Multiple by 10 to determine heart rate. This method works well for both regular and irregular rhythms. In the first image, we can count 7 QRS complexes, so the heart rate is 70.

The second method uses small boxes. Count the number of small boxes for a typical R-R interval. Divide this number into 1500 to determine heart rate. In the second image, the number of small boxes for the R-R interval is 22.5. The heart rate is 1500/21.5, which is 69.8

Question 10

The cardiac cycle

Answer 10

is a term referring to any or all of the events related to the flow or blood pressure that occurs from the beginning of one heartbeat to the beginning of the next.

Question 11

5 PHASES OF THE CARDIAC CYCLE

Answer 11

 1. Isovolumetric Ventricular Contraction

 2. Ventricular Ejection
 3. Isovolumetric Relaxation
 4. Ventricular Filling
 5. Atrial Systole

Question 12

ISOVOLUMETRIC VENTRICULAR CONTRACTION

Answer 12

 Response to ventricular depolarization (QRS)

 Tension in the ventricles increase
 Pressure increases: closes MV and TV
 PV and AV stay closed during entire phase

Question 13

Pressure vs tension

Answer 13

The ventricle develops tension, not
pressure (P=QR)

Question 14

VENTRICULAR EJECTION

Answer 14

 When ventricular pressure > aortic and pulmonary pressure -
the AV and PV open
 Ejection is about 70 % of the blood

(EF %) Ejection Fraction = SV / EDV