ECG Flashcards
what is the pacemaker pace of the SA node?
60-100bpm
what is the pace of the AV node?
40-60
what is the pace of the ventricle cells?
20-40bpm
what is preload?
The amount of stretch on the right ventricle from blood returning to the heart
More stretch = more forceful contraction….up to a point!
what is after load?
The force against which the left ventricle must pump
systemic vascular resistance – SVR
how many electrodes are you putting on your patient for a 12 lead?
- 6 chest leads and 4 limb leads
what are leads?
leads refer to the tracing of the voltage between the electrodes on the ECG printout
(idk if we need to know this) which leads are the interior leads?
leads II, III, and aVF. Look at electrical activity from the vantage point of theinferiorsurface (diaphragmatic surface of heart)
(idk if we need to know this) what leads are the lateral leads?
(I, aVL, V5and V6 ) Look at the electrical activity from the vantage point of thelateralwall of leftventricle
(idk if we need to know this) what leads are the septal leads?
(V1and V2) Look at electrical activity from the vantage point of theseptalsurface of the heart (interventricular septum)
(idk if we need to know this) what leads are the anterior leads?
(V3and V4) Look at electrical activity from the vantage point of theanteriorwall of the right and left ventricles (Sternocostal surface of heart)
what does a positive waveform mean?
electrical current moves towards the positive electrode
if the current moves away from the positive electrode what does the wave look like?
inverted waveform
how are the leads placed for a 5 lead? remember the saying think she used
RA white (white to the upper right), RL green (clouds over grass), LL (left leg red- smoke over fire), V1 smoke over fire, LA left arm (black)
what does the P wave mean?
atrial depolarization
what does QRS mean?
ventricular depolarization
what does T wave?
ventricular repolarizatin
how many seconds is one small box?
0.04 s
how many seconds is one large box?
0.2 s
what is the amplitude of one large box?
0.5mV or 5mm
what are the normal features of the P wave: height, seconds duration, placement?
Precedes the QRS
2 – 3mm high
0.6 – 0.12 seconds duration
Rounded, smooth, and upright in lead II
what is important to evaluate when looking at the PR interval? what is happening during this time?
duration. tracks the atrial impulse from the atria through the AV node, bundle of his and r and l bundle branches
what is the duration of the PR interval?
0.12-0.2 seconds
what do changes in the PR interval indicate?
an altered impulse formation or a conduction delay, as seen in AV block
what do you pay special attention to when evaluating the QRS complex?
duration and configuration
characteristics of QRS complex? location, duration, height, what does it consist of?
follows PR interval.
5 to 30 mm high but differs for each lead used
0.06 to 0.10 second, or half of the PR interval
consists of the Q wave (the first negative deflection after the P wave), the R wave (the first positive deflection after the P wave or the Q wave), and the S wave (the first negative deflection after the R wave
where does the PR interval start and end?
starts at the BEGINNING of the p wave and the BEGINNING of QRS
what do you pay attention to for the St segment?
pay attention to deflection
where is the ST segment?
extends from the S wave to the beginning of the T wave
is the ST segment positive or negative?
usually isometric (neither positive or neg)
the point that marks the end of the QRS complex and the beginning of the ST segment is known as the
J point
what does a change in the ST segment indicate?
myocardial damage. might be elevated or depressed
what do you evaluate when looking at a T wave?
amplitude, configuration and deflection
what is the height of the T wave? duration?
.5mm and duration is not measured
what do you look at for the Qt wave? where is it?
the duration.
beginning of QRS and end of T wave
what does the WT interval measure? when does it vary?
vernacular depolarization AND repolarization.
varies according to heart rate
prolonged Qt intervals indicate what?
relative refractory perid is longer.
it is a congenital conduction- system defect in families
short QT intervals may result from what?
dignoxin toxicity or hypercalcemia
is the U wave always present? where is it? what does it look like?
no. after T wave. rounded and upright
what is the U wave?
represents the recovery period of the Purkinje or ventricular conduction fibers
a prominent U wave may be due to what?
hypercalcemia, hypokalemia or digoxin toxicity
what are the 8 steps for an 8 step interpretation?
- determine the rhythm
- determine the rate
- eval the P wave
- measure the PR interval
- measure the QRS
- eval the T wave
- measure the QT interval
- note any abormalities and conclude your analysis
how do you determine the rhythm?
measure from P-P and R-R
are they regular ? using caliper or paper
how do you determine the rhythm?
Count the small squares between two consecutive P waves and then divide 1,500 by that number to get the atrial rate. To obtain the ventricular rate, use the same method with two consecutive R waves. ie: 1500/20 = 75 BPM
or
print a 6 second strip and count number of P waves and multiply by 10 and repeat for R waves
every 3 sec is marked
what do you ask yourself when evaluating the P wave?
How do they look? Normal? Upright? Rounded? Are they all a similar size and shape?
Is there one P wave per QRS complex?
how do you measure the PR interval?
count small squares between the P and beginning of QRS and multiply by 0.04
how do you measure the QRS?
Measure from the end of the PR interval to the end of the S wave
Count the number of small squares and multiply by 0.04
what do you ask yourself when evaluating the t wave?
Are there T waves?
Are they upright in lead II?
Are they all the same shape?
Does each T wave follow a QRS complex?
how od you measure the QT interval?
Count the number of small squares between the beginning of the QRS complex and the end of the T wave, where the T wave returns to the baseline and multiply by 0.04
does the QT interval increase or decrease when the heart increases?
decreases
what do you ask yourself for abnormalities ?
Are there any ectopic beats?
Anything else unusual?
Is the ST segment isoelectric? Elevated? Depressed?
Record and document your findings
how do you document your analysis?
name your strip based on:
The origin of the rate (sinus node, atria, AV node, or ventricles)
The rate (bradycardic, tachycardic)
Rhythm abnormalities (flutter, fibrillation, heart block, escape rhythm, or other arrhythmias)
