Final cardiac Flashcards
(377 cards)
What is the conduction pathway in the heart
- SA node
- Intra atrial pathways
- AV node
- Bundle of His
- Left and right bundle branches
- Purkinje fibers
Does the parasympathetic nervous system increase your SA node or decrease? What about the sympathetic nervous system?
The parasympathetic system slows the SA node (it’s like the brake)
The sympathetic system increases the SA node (it’s like the gas)
What do the waves and the intervals stand for on an ECG
P wave = depolarization of the atria
PR interval = time for the impulse to spread through the atria
QRS = depolarization of the ventricles
ST = time between ventricular depolarization and repolarization
T wave = repolarization of the ventricles
QT interval = time for entire depolarization and repolarization of the ventricles
How many seconds is a typical strip
6 seconds
How many seconds is a big box and how many seconds is a little box
Big box = 0.2 seconds
Little box = 0.04 seconds
What is the rate of the SA node and the atria
60-100
What is the rate of the AV node and bundle of His
40-60
What is the rate of the bundle branches and purkinje
20-40
How many seconds should the PR interval be?
0.12-0.20 seconds (about 3-5 little boxes)
How many seconds should the QRS complex be
Less than 0.12 seconds (less than 3 little boxes)
What is artifact
Artificial ECG info - maybe a lead is lose, pt is up walking around, etc…
What is the absolute refractory period? Why is it important? What part of the ECG wave is it?
When excitability is zero and the heart cannot be stimulated (important with cardioversion - we don’t want to shock the heart when it’s doing something). It’s from Q to the T wave.
How do we diagnosis dysrhythmias? (probably don’t need to memorize - just be familiar just in case)
- Holter monitoring (usually only worn for 24 hours)
- ZIO Patch (usually worn for 14 days)
- Event recorder monitoring (you can control when it records)
- Exercise treadmill testing
- Signal-averaged ECG (multiple ECG’s use averages for dx)
- Electrophysiologic study (“EP Study” with the use of catheters to study the origin of the dysrhythmia)
What are the steps when we look at a rhythm?
- Is the rate regular or irregular? Is it regularly irregular?(R wave to R wave)
- Rate? (multiply the R waves by 10)
- Is there one P wave in front of every QRS? Do they all look the same?
- Is the PR interval normal and consistent?
- Is the QRS narrow or wide?
- Is there a T wave?
How do we know someone is in sinus bradycardia
Rate is less than 60
What can cause sinus bradycardia 9
- Carotid sinus massage
- Hypothermia
- Hypothyroidism
- Increased intracranial pressure
- Obstructive jaundice
- MIs
- Increased vagal tone (when a pt is bearing down and passes out on toilet)
- Administration of parasympathomimetic drugs
- Drugs like beta blockers and CCBs.
What are symptoms of bradycardia
- Hypotension
- Pale, cool skin
- Weakness
- Angina
- Dizziness or syncope
- Confusion or disorientation
- Shortness of breath
(anything that you would see with decreased cardiac output)
What is our tx for bradycardia 4
- Stop offending drug (like beta blocker or CCB)
- IV atropine (1mg) (may or may not work depending on what’s causing the bradycardia)
- Pacemaker
- Dopamine or epinephrine infusion
How do we know someone is in sinus tachycardia
Their HR is over 100
What things can cause sinus tachycardia
Yes - here are the signs
- Exercise
- Pain
- Hypovolemia (Heart is working faster and faster to try and increase cardio output because volume is low)
- Myocardial ischemia (with any kind of ischemia, heart works harder to get blood to that area)
- Heart failure (HF)
- Fever
- Anxiety
- Hyperthyroidism
- Effects of drugs: Levophed, atropine, caffeine, theophylline, hydralazine, pseudoephedrine
How can we treat sinus tachycardia 2
- Treat the underlying cause! (such as pain, fever, hypovolemia (someone is really dehydrated, give them fluids, heart rate goes down)
- Vagal maneuver (have them bear down, blow into a straw)
- Drugs (beta blockers, adenosine, CCBs)
What do (premature atrial contraction) PACs look like
- Caused by ectopic focus (starting from somewhere other than the SA node)
- The p wave looks different, because it is firing prematurely from a different place in the heart (not the SA node), and then it will be followed by a narrow QRS
- This beat occurs sooner than the next expected beat
How can we tell the difference between a PAC and PVC
Since the PAC is coming from the atrium, the QRS will be narrow, versus a PVC, which is coming from the ventricle, the QRS will be wide
If someone has PACs or another dysrhythmia, how would we describe their rhythm
Describe the underline rhythm, like sinus tachycardia, with PACs