Sinus and Atrial Rhythms Flashcards
what are the causes of sinus brady (7)
- inf/post/RV MI
- vagal stimulation
- hypoxia
- increased ICP
- meds
- sa node pathology
- athletes
causes of sinus tachy (8)
- sns stimulation
- hypoxia
- pain
- CHF
- AMI
- meds
- exercise
- fear/XIT
what is the main cause of sinus arrhythmias?
often due to respirations where the heart rate speeds up during inspiration and slows down during expiration
what are other causes for sinus arythmias?
- psns stimulation of baroreceptors
- increased vagal tone
what is sino atrial block?
occurs when the SA node initiates a beat but the signal is blocked which prevents the contraction of the atria. this will cause a brief pause in the rythm
what is the key feature for SA block?
between two p waves the pause is an exact multiple of the distance that p wave should have been
what could cause SA block? (5)
- hypoxia
- SA node damage from MI,CAD,myocarditis
- vagal tone on SA node
- carotid sinus sensitivity
- meds
what is sinus arrest?
this is when the SA node fails to fire altogether for 1 or more beats
how does sinus arrest differ from SA block
this is different because the SA node fails to fire where as in SA block the SA node does fire however the impulse is blocked and does not cause the atria to contract
what is a key feature for sinus arrest
the timming for the next beat is unpredictable in contrast to SA block. the pause can be filled by a secondary pace maker aka junctional escape beat
causes for sinus arrest (6)
- SA node damage (MI, CAD, Myocarditis)
- sudden increase in vagal tone
- carotid sinus pressure
- obstructive sleep apnea
- hypothermia
- meds
more often than not there usually isnt a treatment done for sinus arrest but if there are serious signs and symptoms what treatments could be implimented?
a treatment with atropin, pacing, and possibility of a permanent pacemaker
true or false: premature atrial complexes (PAC’s) dont affect the overall heart rate!
true! unless there is an underlying rhythm
why is PAC’s an irregular rhythm
becaus of the premature/ early beat
what shape should we expect the p wave to be in a PAC?
it could vary because the PAC could come from a different part of the atria. it could be flattened, notched, pointed, biphasic, or event lost in the preceding T wave
what should you know about the PR interval /QRS during a PAC
they could be prolonged or wide respectivly but rare
what could cause PAC’s (10)
- stimulants
- emotional stress
- metal and physical fatigue
- atrial enlargment
- digitalis
- valvular heart disease
- elctrolyte imbalance
- hyperthyriodism
- CHF
- ACS
PAC’s can sometimes initiate ….
A-fib, A flutter, or paroxysmal SVT
what will happen to the RR distance when a PAC occurs
the distance will be shorter
what is a Aberrantly conducted PAC?
the PAC takes an abnormal pathway through the ventricles leading to a wide QRS complex
how does the depolarization pathway to the ventricles occur during a PAC?
the depolarization occurs sequentially first the left bundle banch and then the right which creates the wider QRS
what is a non conductive PAC
a PAC is so early that it enteres a refractory period so the impulse does not reach the ventricles so there is not a QRS complex
how would a non conductive PAC appear as on an ECG
it may appear as a P wave with no QRS and could be mistaken for sinus arrest
what is multiform atrial rhythm formerly known as wandering atrial pacemaker
the impulse from the atria originates from at least 3 different sites above the bundle of his
what is the characteristics of multiform atrial rhythm on an ECG
the size ,shape, and direction of the P waves are different because they orriginate fromm different sites
what is multiform atrial tachycardia
similar to the multiform atrial rhythm but with a rate of >100bpm
what could cause multiform atrial rhytms (4)
- COPD
- ACS
- Valvular disease
- Hypomagnesemia
what is atrial flutter?
a re entry rhythm caused by an irritable site within the atria firing at a rapid rate
what clinical presontation would a pt with atrial flutter show
- palpations, difficulty breathing, fatigue, and chest discomfort
what could cause atrial flutter (5)
- hypoxia
- ischemic heart disease
- various cardiac pathologies
- CAD
- cardiomyopathies
-MI complications
what would a treatment be fora a pt that has a rapid ventricular rate and atrial flutter with serious S/S
synchronized cardioversion
what is atrial fibrillation
its when the electrical signals in the atria are disorganised and firing in multiple locations
where do the lectrical signals in a fib often originate?
from the pulmonary veins
what is the definiton of SVT?
tachycardias that originate above the bundle of his
what are the three types of narrow complex SVTs?
- Atrial tachycardia
- AV Nodal Reentrant Tachycardia (AVNRT)
- AV reentrant Tachycardia (AVRT)
what are characteristics of AVNRT?
rate: 150 - 250 , typically 180 to 200
rhythm: regular
waves: p wave is often hidden in QRS, PR intervals is not measurable, QRS gennerally narrow
how does a PAC cause re-entry resulting in SVT?
while the fast pathway is in refractory, the PAC may enter the AV node through the slow pathway which can lead to reentry
what are retrograde p waves in AVNRT
a small sip or inversion before the T wave on an ECG
what is AVRT?
AVRT involves a accesory pathway that by passes the AV node
true or false, accesory pathways in AVRT are typically congenital and present at birth?
true!
anterograde conduction
impulses travel from the atria to the ventricles through an accessory pathway
retrograde conduction
impulses travel back up through the accessory pathway
bidirectional conduction
accesory pathway can conduct impulses in both directions
true or false: the accesory pathways conduct impulses faster than the AV node.
TRUE
what is wold parkinson white syndrome (WPW)
A type of svt where an accesory pathway known as the bundle of kent allows impulses to bypass the AV nide
what are characteristics of WPW
- delta wave in the QRS
- shorter PR interval
- possible wodened QRS
- ST and T wave abnormalities
WPW with SVT
the impulse circulates through the accesoray pathway and av node creating a re entry circuit
what are the two types of AVRT
orthodromic AVRT and Antidromic AVRT
orthodromic AVRT + characteristic
conduction antegrades through the AV node then up through the accesory pathway
Rate: 200- 300
ECG : narrow qrs with hidden p wave
Antidromic AVRT + characterisitic
the conduction proceeds down the accessory pathway then retrogrades up the av node
rate: 200-300
ECG: wide QRS like V tach
