A&P Test 4 Flashcards
What are the causes of arrhythmias?
abnormal rhythmicity in the pacemaker
* Firing faster/slower
* current sent in a wrong direction
* ectopic pacemaker
Shift of pacemaker from sinus node
Blocks at different points in the transmission
* might cause ectopic pacemaker
Abnormal pathways of transmission in the heart
* normally have a very defined pathway and speed. Ectopic pacemakers might cause AP to go in a different path
Spontaneous generation of abnormal impulses from any part of the heart
* VRM increased
What can cause an ectopic pacemaker in a pacemaker cell?
Increased VRM
Things that increase VRM are things that prevent the heart from _________
Resetting itself
I.e Ischemia in the AV node increase VRM so that the AV node still fires but it is an abnormal beat aka arrhythmia
Anything that increases VRM increases the risk of what
An ectopic pacemaker
Increased K+ levels in the blood leads to an increased ________
VRM
Tachycardia
Abnormal Sinus rhythm where the SA node is firing faster than normal d/t an abnormal SA node. This generates a faster P wave
With sinus tachycardia we should have a normal ____ on the EKG and a short ______
normal looking EKG with a normal P wave
and Short PR interval
What defines Sinus Tachycardia?
HR >100 BPM
What causes ST?
- Increased body temperature
- Reflex stimulation of the heart by the sympathetic system or a loss of stimulation of the vagus system
What toxic conditions did Dr. Smidt mention that increase VRM and can cause ST?
Nicotine
Alcohol
Acidosis
Hyperkalemia
What is the definition of sinus bradycardia?
HR <60 BPM
a normal EKG, just slow
What happens in athletes with a physicological hypertrophy of the heart?
They have a high Stroke volume
Slow heart bc of high stroke volume, don’t need as many BPM
Vagal stimulation to slow down the HR if high HR isn’t needed
What causes sinus bradycardia?
Being an athlete (physiologic hypertrophy)
In general, having a ____ HR is a good thing
Low
If you have a high resting heart rate, your _____ probably isn’t what it is supposed to be
Stroke volume
High resting HR is usually d/t
Hyperthyroidism
Could be a valve problem
Causes for bradycardia
Usually d/t increased vagal
Neural reflex to drugs (increase in HR, baroreceptors see this, phenylephrine increases HR)
Decrease in sympathetic nervous system
Atrial tachycardia that comes and goes
Paroxysmal atrial tachycardia
What does Paroxysmal tachycardia look like in a pt.?
What would cause this?
Sometimes we have normal R-R intervals and sometimes we have fast HR
Something that temporarily blocks vagal stimulus. When the vagus nerve goes back to normal HR goes back to normal
What do the P & T waves look like atrial tachycardia?
T wave goes away, it is hidden under the QRS. They overlap and become indistinguishable.
P wave goes away when the _____
SA node is ischemic
When the SA node is blocked what happens?
The fastest self discharge rate tissue takes over as the pacemaker of the heart
Usually AV node
If AV node isn’t working then
Purkinje fibers take over but gives us a very slow heart rate
If you have a ventricular rate of 20 , what kind of activity can you do?
You can maybe walk around your house but can’t be a professional basketball player
Depending on which part of the AV node is sending out an AP what might happen?
You could have an inverted P wave d/t the AV sending retrograde AP towards the SA node.