L11 - arrththymia Flashcards
what does ECG measure
electrical activity
what happens during P wave
atrial depol
what happneds during QRS complex
ventri depol
what happends during T wave
ventri depol
what is R-r interval
calculates HR
what is P-R interval
from start of atrial depol to the start of ventr depol
what is QRS duration
total time of ventric depol
what is Q-T interval
from start of ventr depol to the end of ven depol
- used to get info about AP duration (APD)
what is arrythmia
disturbnace in the rate or rhythm of the heart beat
what is sinus rhythm
normal one
what is tachcardyia
has shorter r-r intervals
-has a faster HR
what is bradycardia
longer R-R intervals
-slower HR
causes of arrhythimas
- loss of electrical activity
- genetic associated with environmental
- can reduce CO
- most common arryhthimas is atrial fibrilla tion
classification of atthythimas regarding the location
superventic- location above the ventricles
ventricular - in the ventricles
classification of atthythimas regarding the mechanisms
- triggered ectopic activity - leading to DADs and EADs
- disturbances in conduction - like AVN conduciton and re entry circuit formation
what is ectopic activiity
when other site in the heart (not SAN) start to generate their own heart activity
- most commonly in posteroir left atrial wall
causes of ectopic activity
DADS - delayed depol EADS - early afterdepol
how does DADs leads to ectopic acitvity
- Ca overload in the SR so it leaks out
- Ca removed by the Na/Ca exchanger so One Ca ion out and 3 Na ion in
- there is net charge of 1+
- RMP becomes positive and leads to depol inwards current
how does EADS lead to
- caused by a prolongation fo APD with reduced K efflux
- prolongation allows for L type Ca channels to recover and reactivate
causes od conduction disturbances in arryhthima
AVN conduction block - electrical wave not passed through the AVN
- re entry circuit formation
what is re entry circuit formation
one or multiple self sustaining circuits in the hearts
types of re enrty circuits
macro, micro , muiltple micro circuits
- increase HR
how are re entry circuits fromed
- when there is a damaged tissue in the heart
- once it repairs, the it causes the circuits to be in loop rather than in one direction
factors affecting the formation of re entry circuits
slower the conduction velocity
the shorter refractory peroid is
shorter the wavelength ,
the more likely the re entry circuits will be formed
what determines the time of refractory peroid
by the no of available and recovered VG NA channels
what does shorter APD lead to
- rapid return to the neg RMP
- Na channels recover faster
- shorter refractory peroid
- re entry circuit
what does longer APD lead to
NA channels recover more slowly and longer refractory peroid
- but ifits too long, can cause EADs
what determines CV
charge graident between 2 cells
what happens if the depol current is reduced
- longer to reach threshold as the charge gradient is reduced
- reduces CV and increase risk for ren enrty circuit
classes of anti arrhythimic drugs (AADs
1,2,3,4
what is class 1 AAD
VG Na channel blocker s
what is class 2 AAD
B adrenoreceptor antagonist
-decrease SNS activity
what is class 3 AAD
VG K channels blocker
what is class 4 AAD
L type Ca channel blocker
