Lecture 1: Dysrhythmias Flashcards
define depolarization
process where resting membrane potential of heart becomes more positive. occurs when Na and Ca2+ ions flow into cells leading to rapid change in cell’s electrical charge.
heart sends signal, causing cells in atria and ventricles to depolarize. causes the muscle fiber to contract.
this initiates the contraction of heart muscle, which pumps blood through the chambers.
inside of cell becomes more positive (sodium, potassium and chloride needs to move for contraction for heart to beat)
Ectopic
(SA node is the beginning point of domino effect) we have a coordinated contraction and if the impulse starts in a different locations then it is ectopic (still falls but not right sequence and not as effective)
when heart beats out of its usual rhythm or place.
repolarization
is the process where cell’s membrane potential returns to its resting, negative state after depolarization. during repolarization, K ions move out of cell restoring internal -‘ve charge.
after heart muscle contracts, electrical charge within cells begins to return to baseline. Preparing cells for next depolarization.
allows heart muscle to relax after contraction, so it is ready to contract again.
(all electrolytes move back to where they need to be so it can happen again) happens very quickly
permeability
(sodium, potassium, and chloride needs to pass) changing permeability affects this cycle (meds can alter this cycle)
absolute refractory period
(when sodium and potassium move back to where they need to be (there has not been enough electrolyte movement of electrolytes for depolarization to happen again)
“no entry zone”. time after heart muscle cell has depolarized when it cant fire again no matter what. gives heart time to rest and recover.
relative refractory period
(it could be set off, but not the same magnitude of depolarization if we are only part way through repolarization)
like a “half open door” for heart cells. heart cells can fire again, but only if signal is strong enough. time when heart is still recovering but if the heart gets a big enough push it could beat again.
describe to me how blood moves thru the heart (this is a horrible cue card going to have to whiteboard + look at notes)
- R atrium: blood comes from body, low in o2 into R atrium
- R ventricle: blood moves to the right ventricle
- lungs: r ventricle pumps blood into lungs to get oxygen
- L atrium: oxygen-rich blood returns to heart, entering the L atrium
- L ventricle: blood moves to the L ventricle
- Body: L ventricle pumps oxygen - rich blood out to the body
R atrium -> R ventricle -> lungs -> L atrium -> L ventricle -> body
describe the hearts automaticity
heart can contract by itself, independently of any signals or stim from body. heart contracts in response to electrical current conveyed by conduction sys.
heart attacks SA node
every cell in the heart can start the domino effect
3 main parts of the conduction system for the heart
- (sinoatrial) SA node
- AV node
- conduction fibers within the ventricle, specifically the bundle of His, bundle brances, and Purkinje fibres
describe to me the intrinsic pacemaker rates of cardiac conduction tissue
- If everything is good, SA node is the pacemaker (60-100 beats per minute)
- SA node sends signals to depolarize, the other parts won’t have a chance to take over because everything is synchronized and beautiful
- No SA node, then AV node will say (hey this is not good (less than 60 beats a min), it will start depolarizing at a rate of 40-60
- Less than 40 per minute, then the Purkinje fibers will start (40-15)
- It is a failsafe method
This is dysrhythmia
describe cardiac monitoring and telemetry (6 lead)
- Top is cardiac monitoring strip (usually they have 2)
- Connected straight to wall and monitored at bedside
Portable units around their neck (wires connect to stickers on chest)
describe an ECG
- Heart from different views
- Tracings of electrical energy as it moves towards a lead
- Looking from a different view of the heart
- Energy moves as it depolarizes (energy coming towards me is more positive)
- Going up means net energy is moving towards it
- Positive when coming towards the lead (positive deflection), then drops when it goes away (negative deflection)
- Ventricles (bigger QRS) is representative of the current as it goes through (bigger whether positive or negative)
- Think of the lead as an eye
Lead 2 is most easy to read
describe cardiac monitoring
- Emergency (chest pain, SOB) to see changed (shows PQRST)
- Quick view to show us anything obvious with the heart
- Lets us know HR, disease or injury, pacemaker function, evaluates if a med is working
Evaluate if a patient is having an MI
3 lead or 5 lead
describe a 12 lead ECG
One is bisecting and the other looks at planes (look at the diagrams)
describe 5 lead cardiac monitoring (pic on the slides insert later)
- LL left leg
- RA right arm, etc
- Colour coordinated
White to the right, smoke (black) above fire (red), brown at the chest, white clouds over green grass
define afterload
what are we pumping against
(pressure or resistance against which ventricles pump to eject blood)
Preload
force exerted at the end of diastole (filling), and we are now going to contract, once they are filled that is preload. Preload determines how effective our contraction is going to be
describe contraction
mechanical event
ability of cardiac cells to shorten, causing cardiac muscle contraction in response to electrical stim
venous return
blood amount going into right atrium
stroke volume
amount of volume moved out of ventricles
ejection fraction
% of blood pumped out of ventricle with each contraction (each ventricle ejects a % (50-80%) (more volume in ventricle the more volume)
cardiac output
stroke volume (that goes out with each contraction) then multiple by contraction (HR per minute)
diastole
rest period with filling
term implies ventricular diastole
bp
force exerted by circulating blood volume
shock
not getting output we need
systole
contraction of heart where blood is propelling into pulm artery and aorta (implied ventricular systole)
heart failure
condition where heart is unable to pump enough blood to meet metabolic needs of body, may result from any condition impairing preload, afterload, cardiac contractility, HR
define cardiac cycle
1 complete mech cycle of heartbeat, beginning with ventricular contraction and ending with ventricular relaxation
describe the cardiac cycle
- Majority of filling in ventricles is passive
- Atrial kick at the end, pumps the last bit from the atria into the ventricles
- Ventricles are full of blood, there is higher pressure in fill ventricles
- AV valves that were open, now snap shut (S1)
- Closed system (AV and pulmonary valves shut)-isovolumetric contraction
- Ventricular muscles tense and contract, when pressure is at its peak, aortic and pulmonic valve open, and blood leaves-ventricular systole-blood moves forward
- Ventricle are now less blood filled, pressure is now greater in aorta and pulmonary system
- Aorta and pulmonic valves snap shut (S2) isovolumetric relaxation (closed system)
- Atria that fills (pressure is greater), AV valves will open, this is now passive filling into ventricles and depolarization in atria, at the end is contraction and atrial kick
Atria empties and ventricles is full, valves shut (isovolumetric relaxation)
5 steps of cardiac cycle
- atrial systole
- isovolumetric contraction
- ejection
- isovolumetric ventricular relaxation
- passive ventricular filling
before depolarization describe the electrolyte concentrations
- Inside of heart is more negative (depolarized state)
- Blood levels are the same basically
- More potassium, sodium, and calcium in the cells vs outside
- Inside of cell is more negative
After repolarization we want the electrolytes to return to this so that depolarization can occur
describe depolarization
- Depolarization is electricity going through muscle
- Does not mean heart contracts
- We hope that the heart is contracting
- Check pulse to see if they are contracting
- If someone’s heart does not pump
- NOT the same thing
- We hope that one causes the other
- Depolarization is an electrical event
Contraction is a mechanical event
describe the phase 0 of action potential
1. description
2. ionic movement
3. mechanisms
- Upstroke
- Na+ into cell, K+ leaves the cell, Ca2+ moves slowly into cell
- Fast Na+ channels open
describe the phase 1 of action potential
1. description
2. ionic movement
3. mechanisms
- Overshoot
- Na+ into cell slows, Cl- into cell, K+ leaves cell
- Fast Na+ channel close partially
describe the phase 2 of action potential
1. description
2. ionic movement
3. mechanisms
- Plateau
- Na+ and Ca2+ into cell, K+ out
- Multiple channels (Ca2+, Na+, K+) open to maintain membrane voltage
describe the phase 3 of action potential
1. description
2. ionic movement
3. mechanisms
- Repolarization
- K+ out of cell
- Ca2+ and Na+ channels close; K+ channels remains open
describe the phase 4 of action potential
1. description
2. ionic movement
3. mechanisms
- Resting membrane potential
- Na+ out, K+ in
- Na+-K+ pump
define a rhythm stip
- graphic tracing of electrical impulses
- movement of charged ions across membranes of myocardial cells creates certain wave forms on the tracings
- wave forms represent depolarization and repolarization of myocardial cells
describe a rhythm strip
graphic tracing of electrical impulses
movement of charged ions across membranes of myocardial cells creating wave forms on tracings
wave forms represent depolarization + repolarization of myocardial cells
S1
at beginning of ventricular depolarization
S2
beginning of ventricular repolarization
what is a cardiac monitor paper
graphical display of electrical energy generated by the heart over time
- 0.04 seconds (memorize this number)
- One little box is 0.04 seconds is 1mm
Each dash is 3 seconds between (6 seconds on the image total)
define waveforms
standard paper speed - 25mm/s
how many seconds is P waves
0.06 to 0.12 sec
P Wave: atrial depolarization
how many seconds is PR interval
0.12 to 0.20 sec
represents the time it takes an impulse to travel from atria to atrioventricular node the bundle of His, and the Purkinje fibres
how many seconds is QRS complex
0.06 to 0.12 seconds
Longer than that, longer than normal to depolarize through ventricles, something is slowing it down
how many seconds is ST segment
deviation from baseline
how many seconds is QT interval
0.34 to 0.43 seconds
at normal HRs, the QT interval is less than one half of the R-R interval when measured from one QRS complex to the next
distance btwn every complex should be _______________
the same (use paper to mark each QRS and then slide to ensure they are equal)
look at ipad notes for rhythm determination
how do we calculate HR
- Count number of complexes in a 6 seconds strip and multiply by 10 (gives HR per minute)
- All test strips will be 6 seconds
Irregular rhythms this is just an estimate
When on a monitor, this can be consistent if you have a regular HR
Look to make sure its staying consistent, and if its inconsistent we can make it into a range on their chart
The strip will have pt name, date, time, etc. - quick way to figure out HR
Not the best method is HR is irregular
On exam they will all be 6 second strips
describe P wave
- SA node depolarizes, and goes through atria to beginning of AV node
- Time it takes for all that movement should be 0.12-0.20
Want our P waves to all look the same
If our Impulses are at the same spot, P wave will look the same
P wave is atrial depolarization
If P wave is abnormal you know this is a atrial issue
what is a controlled HR, brady… etc
HR being controlled means HR less than 100
Brady is less than 50
Athletes run a lower HR
105,110, 120 - this isn’t good, there’s lots of things that can happen when our HR is too high for too long that’s bad long term
Exercise increases HR, BP may also increase, mechanism the body has to meet the needs of the body
Overall is not a great thing for our functioning
Majority of our atrial filling is passive, systolic kick adds the final bit of blood
Need to have good contraction, when the kick happens we want it at the end
Passive filling is time #1 factor
If a HR too fast, not enough blood can enter atria before it closes
Have to think about the “backroom” why is tachy bad
what is diastole
when there’s rest: we lessen diastole if HR is really fast, means less blood flow to the heart vessels
what is systole
when there’s contraction
if P wave is prolonged what does this mean
If P is prolonged the depolarization is slowed down, something is going on
If tissue is dead, if someone had a heart attack affecting the AV node, if they have a lytes imbalance
1.describe what a P-QRS ratio should look like
2.what happens if there is P without QRS
3.and QRS without P
- every P for every QRS
- P without QRS means it did not go thru AV node
- QRS without P, then it started in ventricles
P is SA node
What is QRS
ventricular depolarization
the R side of our heart is…
pulmonary
the L side of our heart is…
systemic
if we have P without QRS
If we don’t have this we can have P without a QRS, which means atria depolarize but our ventricles did not, or no P but QRS meaning no action in atria, but ventricles depolarized
how do we want our SA node, and our ventricles
Every part of heart has its own rate, and own descending values
We want our SA node is coordinated and well timed, that follows w atria and ventricular depolarization
Our ventricles can do one of two things - they can depolarize early, or they can be waiting and waiting and nothing comes from AV node, we want our ventricle to depolarize itself for C/O
tell me about the Q wave.
if they are having wide and deep waves what is this
vice versa for shallow and narrow
Q wave - many ppl don’t have this actually
If they are wide and rly deep, they are called pathological which is abnormal - usually means they have had a heart attack and this is the remanence
Shallow and narrow is normal
If you don’t have a negative deflection, don’t have a Q wave
describe T wave for me
0.10 - 0.25 seconds ST segment
this is the repolarization of ventricles
sodium and potassium return where they should be
can you describe to me the difference between absolute and relative
This is super imposing phases of the cardiac cycle over rhythm strip
As we come into downward slope we are making K and Na back to where they are supposed to be
Flat is when ventricles are repolarized
Na or K not enough - absolute refractory period
Relative - there is enough for a possible reaction from cell
The reason we know this is because later we are going talk about defibrillating patients
what happens if u defibrillate a normal person
it could cause an abnormal rhythm and cause something that changes C/O
what does the QT interval represent
electrical depolarization and repolarization of the ventricles
Electrical depolarization and repolarization of the ventricles
Some meds, some abnormalities can expand this period
We want to monitor this
define artifacts you’d see on a ECG
look at ipad
describe to me what a normal sinus rhythm looks like
Heart rhythm:
HR:
P waves:
P to QRS ratio:
PR Interval:
QRS Complex:
Treatment:
Heart rhythm: regular
HR: 60-100 bpm
P waves: uniform and upright
P to QRS ratio: 1:1
PR Interval: 0.12-0.20 seconds
QRS Complex: narrow, less than 0.12 seconds
Treatment: none
describe to me what a sinus tachycardia looks like
Heart rhythm:
HR:
P waves:
P to QRS ratio:
PR Interval:
QRS Complex:
Treatment:
Heart rhythm: regular (impulse origin remains SA node)
HR: greater than 100-180 bpm
P waves: uniform and upright
P to QRS ratio: 1:1
PR Interval: 0.12-0.20
QRS Complex: narrow, less than 0.12 seconds
Treatment: consider slowing HR (looking at underlying cause, metoprolol), consider that increased HR may be in response to decrease stroke volume
describe what a sinus tachycardia can cause and potential s/s
- can increase or decrease CO, response is highly individualized and influenced by atrial rate, contractile state of myocardium and circulating blood volume
- dizziness and hypotension due to decreased CO
- increased myocardial oxygen consumption may lead to angina
you want to understand whats going on**
describe to me what a sinus bradycardia looks like
Heart rhythm:
HR:
P waves:
P to QRS ratio:
PR Interval:
QRS Complex:
Heart rhythm: regular
HR: less than. 60 bpm
P waves: uniform and upright
P to QRS ratio: 1:1
PR Interval: 0.12-0.20 seconds
QRS Complex: narrow, less than 0.12 seconds
atropine, transcutaneous pacing
treatment for sinus bradycardia
- only symptomatic bradycardia needs to be treated
- atropine 0.5 mg IVP q3-5 mins up to 3 mg
- transcutaneous pacing
- consider pt’s current medications: example too much metoprolol can make them quite bradycardic
describe the C/O of sinus bradycardia
- CO is not significantly decreased until rate falls below 50 bpm. when HR falls below 50 bpm CO may be inadequate to meet the bodies o2 demands
s/s of sinus bradycardia
hypotension, pale cool skin, weakness, angina, dizziness, syncope, confusion, disorientation, SOB
what are atrial dysrhythmias
- atrial dysrhythmias reflect abnormal electrical impulse formation and conduction in the atria
- most atrial dysrhythmias are not life-threatening
- increases in HR shorten all phases of the cardiac cycle
Most are non-life threatening is bc the majority of filling into the ventricles is passive, so we don’t have a contraction of the atria - as long as we have a controlled HR (less than 100) and lost the atrial kick most people are okay (many ppl have this and aren’t in any immediate danger) not perfect we don’t love them but not the worst thing
When they start having HF,and other CVS issue this is a much bigger issue
Shortening of the filling
Atrial rhythms can be fast
tell me how to identify premature atrial contraction
Heart rhythm: regular except for premature beats (impulse of origin of underlying rhythm remains in SA node)
HR: usually in normal range (60-100 bpm)
P waves:
regular P wave - uniform, upright,smooth, rounded
premature beat - upright, flattened, notched
P to QRS ratio: 1:1 or QRS may be absent following premature P wave
PR Interval: 0.12-0.20 seconds
QRS Complex: narrow, less than 0.12 seconds
if the irritable site is close to SA node, the atrial P wave will look very similar to P waves initiated by SA node
treatment for premature atrial contraction
usually none, assess pt status
describe to me what afib looks like
Heart rhythm:
HR:
P waves:
P to QRS ratio:
PR Interval:
QRS Complex:
Heart rhythm: atrial and ventricular rhythms are irregular
HR: atrial rate 350-700 bpm, ventricular rate varies, usually slower (can be controlled afib [less than 100] or uncontrolled afib [greater than 100])
P waves: no consistently identifiable P wave
P to QRS ratio: more fibrillatory waves than QRS
PR Interval: not measurable
QRS Complex: usually narrow, less than 0.12 seconds
treatment for afib
conversion, rate control, anticoagulation, ablation
give me the general gist of afib
When someone is in Afib, no depolarization, no consistency, many spots in the atria that are excited depolarizing and causes a wacky rhythm
No normal beats, changes the rhythm
No coordinated flow, or coordinated contraction
No coordinated kick at the end
As long as we are controlling their HR, we aren’t affecting ventricular contraction
All of these impulses are hitting the AV node (gatekeeper) if its letting random bits through
Pulse is irreg
Treatment: convert back itno normal sinus rhythm, but this is very hard
Can use electricity or meds
If HR is 60, we don’t need to give the med bc its controlled
But if its 100+ obvi give
When blood pools it clots, this can cause risk of blood clots, strokes, PE (R side), L side can go anywhere else
Treatments are in order of what you should do
describe to me what atrial flutter looks like
Heart rhythm:
HR:
P waves:
P to QRS ratio:
PR Interval:
QRS Complex:
Heart rhythm: atrial regular, ventricular may be regular or irregular
HR: atrial rate 250-300 bpm, ventricular rate varies, usually slower
P waves: flutter waves
P to QRS ratio: more flutter waves than QRS
PR Interval: not measurable
QRS Complex: usually narrow, less than 0.12 sec
treatment of atrial flutter
conversion, rate control, anticoagulation, ablation therapy
give me the sparknotes of atrial flutter
Excitability in one spot - Afib is everywhere
Sawtooth P waves bc its coming from the same spot
More So likely this will feel reg
We control this w medication or conversion
Ablation since its in one spot is more useful
atrial fibrillation/flutter - describe CO intake and thrombi possibility
- can cause decrease CO due to losing the atrial kick and rapid ventricular response and precipitate HF, angina
- thrombi may form in atria as a result of blood stasis -> may develop and travel to brain causing a stroke
afib /flutter treatment
- CCBs (diltiazem)
- B-adrenergic blockers (metoprolol)
- digoxin
- antidysrhythmic agents (amiodarone)
- cardioversion for new onset afib or afib not responding to meds or unstable pt
describe ventricular dysrhythmias sparknotes version
Inherent rate - sometimes w ventricular contractions this can be a defense mechanism, for example damage this could happen so that contraction happens and cardiac output actually happens
SA generated but blocked
SA nodes fine, but nothing came from above to below, the ventricular would know its not depolarizing so it would do it itself so body can function
Rate of SA nodes is slower - for example from damage
These are all safety mechanisms!
describe ventricular dysrhythmias/when do ventricles become the pacemaker?
- SA node fails to discharge
- impulse from SA node is generated but blocked as it exits the SA node
- rate of discharge of SA node is slower than that of ventricles
- irritable site either ventricle produces an early beat or rapid rhythm
describe to me what premature ventricular contraction (PVC) looks like
Heart rhythm:
HR:
P waves:
P to QRS ratio:
PR Interval:
QRS Complex:
Heart rhythm: regular except for premature beat if impulse of origin of underlying rhythm remains in SA node
HR: usually in normal range (60-100 bpm), depends on underlying rhythm
P waves: regular P wave - uniform and upright
premature beat - absent
P to QRS ratio: PVC will not have a P wave
PR Interval: none
QRS Complex: greater than 0.12, wide and bizarre
treatment for premature ventricular contraction (PVC)
none if CO not impacted, frequent PVC’s can decrease CO as they interrupt diastolic filling
- o2 therapy for hypoxia
- electrolyte replacement
- drugs: B-adrenergic blockers, procainamide, amiodarone, lidocaine
sparknotes of PVC’s
Not a rhythm, it is an isolated beat/complex
There is an underlying rhythm (sinus tach/brad/afib/atrial flutter)
Then randomly your going to have this wide bizarre looking beat
Starts in ventricle so don’t have a P wave w it. So usually looks normal.
QRS is greater than normal bc the depolarization initiating farther so takes longer (starting in a diff place)
4 types of PVC’s
- ventricular bigminy (Bi means 2 means every second one is a PVC)
- Multifocal PVC’s (there are random abnormal beats [one place thats screwed up but these don’t look the same so the tracing over it looks different bc the dominos are falling in different ways])
- coupled PVC’s (2 together)
- short run of VT (3 or more beats)
PVC VS Ventricular escape beat
PVC - premature/early didn’t wait
escape: late, they depolarize themselves
describe to me what ventricular tachycardia looks like
Heart rhythm:
HR:
P waves:
P to QRS ratio:
PR Interval:
QRS Complex:
Heart rhythm: usually regular (impulse origin of VT is on the ventricles)
HR: 110-250 bpm
P waves: usually absent
P to QRS ratio: PVC will not have a P wave
PR Interval: none
QRS Complex: greater than 0.12 sec, are all similar, often wide and bizarre
If you have a pulse u have C/O
If you see this u get a pulse
Stabilize pt, give O2, antiarrhythmic drugs
Unstable: quickly convert them, pulse or no
treatment ventricular tachycardia
CO is compromised. Pulse vs Pulseless.
- stabilize pt - O2, antiarrhythmic drugs to suppress the rhythm (ex: procainamide, amiodarone, sotalol), or defibrillation (pulseless)
Big muscle =
bigger wave (ventricles)
Smaller muscle
smaller wave (atria)
cardioversion
has pulse, VTECH, AFIB, when machine hooked up can mark their rhythm, and where the relative refractory period is, it will delay it so it is not on the relative refractory period
Relative refractory period - we do not shock them!!
Defibrillation: no pulse (no C/O), no coordinated movement, we just want to hit their heart w electricity
ventricular tachy
will come In one spot (one spot is chaotic)
need to determine pulse or no pulse
describe sparknote version of ventricular tachycardia w pulse
- 3+ ventricular beats that are wide and bizarre, in succession at a rate greater than 100 beats per minute are termed ventricular tachycardia (VT)
- there is usually severe underlying myocardial disease
- sustained VT (more than about 30 beats) often degenerates into ventricular fibrillation, resulting in death
describe to me what ventricular fibrillation looks like
Heart rhythm:
HR:
P waves:
P to QRS ratio:
PR Interval:
QRS Complex:
Heart rhythm: reg or irreg (impulse origin of VT is on the ventricles)
HR: unable to determine
P waves: undetectable
P to QRS ratio: none
PR Interval: none
QRS Complex: undetectable
treatment of ventricular fibrillation
No CO - CPR, defibrillation, ACLs protocols = treat underlying cause
sparknotes ventricular fibrillation
- is a chaotic ventricular rhythm that rapidly results in death
- multiple areas within ventricule display marked variation in depolarization + repolarization, resulting in no organized ventricular depolarization (ventricles do not contract as a unit)
Random, no cardiac output
CPR and defibrillate
NOT GOOD
Rapidly goes to death
Faster we defibrillate, the better chance at getting them back
describe to me what asystole looks like
Heart rhythm:
HR:
P waves:
P to QRS ratio:
PR Interval:
QRS Complex:
Heart rhythm: none
HR: none
P waves: usually none present
P to QRS ratio: none
PR Interval: none
QRS Complex: none
treatment for asystole
no CO - CPR, ACLS protocol
fine ventricular fibrillation may look like asystole, it is therefore necessary to check rhythm in more than one lead
*do not defibrillate this rhythm
pulseless electrical activity treatment
CPR, ACLS protocol, identification of underlying cause
Electrical conduction, no mechanical conduction
Heart for some reason is not responding to the defibrillation
Do CPR
Nothing wrong w the electrical conduction, something wrong w the heart muscle pumping itself
Check their pulse
give the sparknotes of defibrillation
they cant tell if the pt has a pulse, but it can tell if they are in asystole, VTACH, AFIB, etc. So it would tell you no shock but keep doing CPR.
Feeling for a pulse, starting CPR, and calling for help, code blue
- assess pt + check pulse
- activate code blue
- start chest compressions
- defibrillate @120-200 joules
- administer o2 if pt hypoxic
