Module 3 Flashcards
How do you calculate the atrial rhythm?
Place the ruler on the P-wave and count three over
-This rule only works if the P-waves are regular and present
How do you count the ventricular rhythm?
Place the ruler on the R-R complex and count three over
What is the PR interval?
The P-R interval represents the amount of time it takes for the electrical impulse to leave the SA node, depolarize the atria, and pass through the AV junction.
What is the normal range of the PR interval?
0.12-0.20 seconds
If the heart rate is faster, the PR is?
Shorter
If the heart rate is slower, the PR is?
Longer
What does the QRS represent?
Ventricular depolarization
-If the wave of electrical activity proceeds in a normal, orderly fashion from the junction, through the remainder of the conduction system and over the right and left ventricles, then we will see a normal QRS complex.
What is the normal QRS complex?
0.10 sec
What does the ST segment represent?
It represents the time during which the ventricles have completely depolarized and repolarization begins
What does ST depression indicate?
Myocardial ischemia
What does ST elevation reflect?
Myocardial injury
When is ST depression or elevation considered significant?
When it is greater than 1mm difference
What does the T wave represent?
Ventricular repolarization; the period of time it takes both the right and left ventricles to recover
If there is no clear ST segment, where does the T wave begin?
At the end of the QRS complex
What does the QT interval represent?
represents total ventricular activity, that is, ventricular depolarization to ventricular repolarization
What is associated with lengthening of the QT interval?
Life-threatening arrhythmia
What is a normal QT?
It is based on the heart rate
What implications on cardiac output do you consider when you are looking at a rhythm strip?
- Is the ventricular rate too slow?
- Is the ventricular rate too fast?
- Is there a P wave?
- Are there any ST changes?
What impact does CO have on a slow rate?
Potential for decrease CO due to the slow ventricular rate
Rate to fast? (Effect on CO)
- leads to decrease in ventricular filling time
- decrease in coronary artery perfusion
- increase in myocardial oxygen demand
- all of the above lead to a decrease in CO
No P wave?
Potential loss of artial kick and therefore a decrease in preload, and therefore a decrease in CO
ST changes?
Poteitnal for ischemia/injury to the myocardium and therefore potential for decrease in contractility, leading to a decrease in CO
What are so inteventions for a rate that is to slow?
-Speed up the heart rate, using drugs or a pacemaker
Rate too fast?
intervention will be to slow the rate down, using drugs or electrical conversion (cardioversion/defibrillation)
No P wave?
Potential intervention will be to chemically or electrically convert the rhythm
ST changes?
Intervention will be to prevent ischemia and injury to the myocardium
What are the 13 steps to analysis a rhythm?
STEP 1: determine the atrial and ventricular rates
STEP 2: assess the rhythm; is it regular or irregular
STEP 3: identify and examine the P waves
STEP 4: examine and measure the P-R interval
STEP 5: identify, examine and measure the QRS complex
STEP 6: locate and examine the ST segment
STEP 7: locate and examine the T wave
STEP 8: locate and measure the QT interval
STEP 9: interpret the rhythm
STEP 10: state the conduction problem if one exists
STEP 11: describe the cause or possible cause of the rhythm
STEP 12: determine the implications for oxygen supply and demand, and clinical significance
STEP 13: decide on interventions
