cardio 2 Flashcards
Normal Sinus Rhythm:
~60bpm
if sinus bradycardia…
Doesn’t mean something is wrong à physiological arrythmia
rate for sinus bradycardia
less than 60 bpm
Rate for sinus tachycardia
> 100bpm
What happens with sinus tachycardia
fever heart rate increases
what happens w/ sinus arrhythmia
on inspiration rate increases, on expiration rate decreases
Goes away as you age
what is 2:1 AV block
AP doesn’t get down the ventricle
Block of conduction or propagation in AV node
why is 2:1 av block problematic?
Problematic because heart rate is 1⁄2 (60 bpm à 30 bpm)
- Cardiac output and blood flow is 1⁄2
- Need pacemaker cells
Every ____ action potential is blocked on its way from travelling from the atrium to the ventricles (in 2:1 av block)
second
where is the 2:1 av blocked?
Blocked either in the Purkinje fibers, bundle of his, bundle branches or in the AV node
rate of ventricle in 2:1 av block
For every 2nd activation of the atrium there is only 1 activation of the ventricle which can
gradually worsen
The rate of the ventricle is 1⁄2
What is a complete Av block
Only P waves, no QRS Complexes & no AP reaches the ventricle
There is one transient wave because it comes back but if it stays you are in complete AV block because you have no cardiac output
treatment for complete AV block
electronic pacemaker
in complete AV block, what happens after P wave
After the P-wave there is a little dip which corresponds to the atrium repolarization
If you look carefully enough 1/12 leads will show atrial repolarization but it occurs at the same time as the QRS wave so you can only see it during complete AV block
can you get complete av block with qrs complexes
You can still get complete AV block with QRS complexes except this time the QRS complexes are
not related in time
- Independent pacemakers
- Normally the SA node is the pacemaker in the heart because other pacemaker areas in your heart usually don’t manifest because they are suppressed
why are other pacemaker areas suppressed in complete Av
The reason they are suppressed is because they get the input from the SA node
at about once/second.
what is the subsidiary pacemaker
During Complete AV block there are some cells in the ventricle that are no longer
subject to this input so the QRS complexes are generated in the ventricles
i.e. they aren’t getting into the ventricles via the His-Purkinje fibers; instead they are getting in via the ventricular muscle, the Purkinje fibers
and one of the bundle branches
if theres a complete av block with no subsidiary pacemaker
just p waves
The rate of subsidiary pacemakers are much _____ than the SA node and sometimes they are
so ____ that the person dies anyways
slower, slow
heart rate, cardiac output and BP too low
systole
ventricles contracting (to draw together/contract)
Isovolumetric ventricular contraction:
o AV valves closed
o Aortic and Pulmonary valves closed
o Atria relaxed
o Ventricles contract
Ventricular ejection
o Blood flows out of ventricle o AV valves closed o Aortic and Pulmonary valves open o Atria relaxed o Ventricles contract
What happens to the AV valve when pressure(ventricles) > pressure(atria)
the AV valve will close which is the start of
ventricular systole
Once contraction of the ventricle starts (vent. eject.)…
the volume starts to increase, called isovolumetric contraction,
volume of the ventricle is constant because both valves are closed -> ‘iso’
