ECG DSA 1 Karius from Website

Question 1

PR interval

What it corresponds to and how it is calculated

Answer 1

AV delay

measured from the beginning of the P wave to the beginning of the QRS complex

typically .12-.20 seconds

the current velocity is around 25 mm/sec, and the boxes are 1 mm/sq, so 1/25= .04 sec/sq

count the number of boxes beginning/end of p wave will give you

3 squares X .04 sec/sq = .12 sec

Question 2

QRS duration

what it corresponds to and how it is calulated

Answer 2

ventricular contraction

the entire width of the QRS is measured, and the sum is multiplied by .04sec/sq

.08 sec

Question 3

QT interval

Answer 3

This segment tells the total duration of the ventricular event, from when the first cell depolarizes to the repolarization of the last cell (which should be the same cell).

The Long QT syndromes are associated with an increased death rate from spontaneous ventricular arrhythmias in otherwise (apparently) healthy individuals. The QT interval is very dependent on the heart rate, so you will often see the designation “QTc”, denoting that the printed interval has been corrected for the heart rate.

. Count the number of squares: 12

2. Multiply the number of squares by the unit time per square:

12 squares x 0.04 sec/square=

0.48 seconds

Question 4

RR Interval

Answer 4

measures heart rate

For Leads, use the distance between R’s
For the aVx’s, use the distance between Q’s

These values = Distance/beat

multiple sqs/beat by the time value .04sec/sq = sec/beat (RR interval)

now, inverting this number gives you beats/sec

multiplying this times the usual factor beats/minute

beats/sec x 60sec/min = beats/minute