Lecture 5: Kirk and Arrhythmia's Flashcards
Draw a sinus rhythm and explain which part represents what
Sinus rhythm shown in picture below
P wave: atrial depolarization
QRS complex: ventricular depolarization
T wave: ventricular repolarization
Explain the rule of 300
aka how to count Heart Rate on the EKG
Count the number of BIG boxes between QRS complex peaks
Then do this math:
(300/ the number of boxes in between QRS peaks) = HR
In a sinus rhythm explain where the heart rate is being paced from
In sinus rhythm, the SA node or the “pacemaker” is the fastest of the automaticity points in the heart, and therefore controls the entire system’s pace
The SA node normally beats about 60-100 beats/min
Explain the wave of automaticity in the heart?
Which beats fastest, and then go down from there
SA Node (60-100)
Atrial Foci (60-80)
Junctional Foci (aka the AV node itself… 40-60)
Ventricular Foci (20-40)
Explain “sinus arrhythmia”
Sinus arrhythmia: (non pathological) variability in heart rate caused primarily by respiratory changes in parasympathetic/”vagal” nerve activity to the SA node
Inspiration causes increase in HR by inhibition of PSNS activity (stretch receptors in lung feed back and decrease HR)
Expiration causes decrease in HR caused by stimulation of parasympathetic nerve activity
What are the four questions you should ask while evaulating every EKG?
What does the answer to each question tell you?
- Are normal P waves present? (is the origian the atria/junctional (supraventricular) or in the ventrical)
- Are the QRS complexes narrow or wide? (narrow is < 0.12 seconds, it is conducted by His-Perkinje system) or not?
- What is the relationship between P waves and QRS complexes? (is there AV dissociation?)
- Is the rhythm regular or irregular?
Explain what an “Escape Beat” is:
An escape beat is essentially a loss of the __________, causing a ______ to kick in and take over
An “Escape Beat” is essentially loss of the SA node overdrive pacing, causing a downstream automaticity foci to kick in and take over (when it is normally overridden by the SA node)
So, you will have a transient Sinus Block, followed by a pause on the EKG and then an automaticity focus where the escape beat kicks in and takes over
Sinus Block:
- SA node firing is __________
- ______ to determine whether SA node failed to fire or fails to cause atrial depolarization
- Difference between sinus arrest and sinus exit block?
Sinus Block:
- SA node firing is not picked up on the EKG
- No way to determine whether SA node failed to fire (aka “sinus arrest”) or fails to cause atrial depolarization (aka “sinus exit block”)
- Sinus arrest means that the AV node failed to fire at all, but Sinus exit block means that the SA node did fire but failed to depolarize the atia
Way to tell the difference on the EKG is whether or not the escape beat pick up on the same pattern (sinus exit block because still paced by SA node)… but this is a unreliable method
Explain an Atrial Escape Beat
Also draw what it will look like on an EKG
Atrial Escape Beat:
In an atrial escape beat, there will be a long pause followed by a P’ wave
This is because the SA node stops pacing, and some atrial pacemaker will kick in and take over (aka the P’)
Explain a “Junctional Escape Beat”
What will that look like on an EKG?
“Junctional Escape Beat” : this essentially means there is a pause in SA node firing, and the “junction”/AV node picks up and causes a ventricular depolarization
On the EKG, there will be a pause followed by a QRS complex… note there is no P’ wave
In this case you can get retrograde P waves from the AV node firing
Explain what a ‘Ventricular Escape Beat’ is
What will that look like on the EKG?
Ventricular Escape Beat:
There will be an SA pause followed by a WIDE QRS complex
This is because some ectopic pacemaker in the ventricles is picking up the slack…you don’t get a nice narrow QRS complex indicating that the wave of depolarization travelled down the His-Perkinje system… because it clearly did not
Explain the difference between escape beats and escape rhythms
Escape rhythms will NOT return back to normal sinus rhythm
AKA beats go back to normal afterwards
Explain what an atrial escape rhythm is
What will that look like on an EKG?
Atrial Escape Rhythm:
P’ waves will all look different, because there might be different atrial pacemaker kicking in each time
The HR will also be slower than normal
Escape rhythms occur with ______
(meaning a very sick SA node)
Escape rhythms occur with sinus arrest
(a very sick SA node)
Explain “Junctional Escape Rhythms”
What will they look like on the EKG?
“Junctional Escape Rhythms” mean that there will be no P’ wave
Ends up in a slower HR (even slower thatn atrial escape rhythm)
“Ventricular Escape Rhythms”
What do they look like on an EKG
‘Ventricular Escape Rhythms”:
There is no p waves and ends up in WIDE QRS complexes
VERY slow heart rate
Ventricular Escape Rhythms:
- Also called _____________ (involves total failure of the SA node and all automaticity foci)
- Rare and dangerous
- Results in fainting called “________”
- Essential a final, futile attempt of ______
Ventricular Escape Rhythm:
- Also called “downward displacement of the pacemaker”
- Rare and dangerous
- Results in fainting (“Stokes-Adam Syndrome”)
- Essentially a final, futile attempt to sustain life
last ditch attempt for the ventricles to save the heart, doesn’t last long, BP will plummet and CO will go down
Premature Beats:
- AKA ______ beats
- Beats that occur _______
- Originates from ________ foci
- Atrial/Junctional/ Ventricular
- Some are _____ others are serious
- Can be caused by ______ toxicity or ____ stimulation
Premature Beats:
- AKA ectopic beats
- Beats that occur earlier than expected
- Originates from irritable foci
- Atrial/Junctional/Ventricular
- Some are innocuous, others are serious
- Can be caused by digitalis toxicity or beta adrenergic stimulation (like asthma inhalers)
What does a Premature Atrial Beat look like on an EKG and what does a Premature Junctional Beat look like on an EKG?
PAB: p’ followed by a QRS that happens to be earlier than normal
PJB: QRS wave that comes in without a p’ wave earlier than normal
Explain what a “Blocked PAC” is
What will it look like on the EKG?
Blocked PAC:
- the SA node fires so early that the AV node is not repolarized yet, therefore you get a P wave with no QRS complex to go with it
The ventricles are not yet repolarized and therefore can’t fire
PVC:
Ventricular Foci Become Irritable Because:
- Low ____
- Low ____
- Other pathologies (like _____)
PVC:
Ventricular Foci become irritable because:
- Low oxygen (very sensitive indicator of ischemia)
- Low K+ (hypokelemia)
- Other pathology (mitral valve prolapse, myocarditis)
PVC’s usually have long compensatory pauses because the beat after is strong (long time for ventricles to repolarize, long time for Ca to enter and preload to happen)
Explain what the EKG will look like for:
A. Single PVC
B. Bigeminy or Trigeminy
C. Multiforme
Single PVC: pretty common, one weird wide QRS
Bigeminy or Trigeminy: 1 PVC : 1 Normal Beat or
2:1
Multiform: runs of three or more, multiform (different appearances of PVCs)
Explain what an R on T is
What will it look like on an EKG?
R on T’s are when a PVC happen during the downstroke of the T wave
The donstroke of the T wave is a vunerable period (relative refractory). If a PVC hits then, it can lead to runs of PVCs (ventricular tachycardia)
What is SVT/Paroxysmal Supraventricular Tachycardia?
What does it look like on an EKG?
SVT:
Essentially the heart is being paced faster than normal by something above the ventricles
Atrial tacycardia will have all p waves
Junctional tachycardia will have no p waves
Carotid Massage:
- Goal: Increase _____ activity to slow sinus firing and conduction through the AV node
- Trick ______ into sensing _____ and therefore ____
- Will only fix _____
Carotid Massage:
- Goal: Increase vagal activity to slow sinus firing and conduction through the AV node
- Trick baroreceptors into sensing high BP and decrease sympathetic and increase parasympathetic
- Won’t fix vtach, only SVT
What is Atrial Flutter?
What does it look like on an EKG?
Atrial Flutter:
SAW TOOTH PATTERN
250-350 bpm
Single extremely irritable atrial automaticity focus
Back to back identical atrial depolarization
Beats are regularly spaced out
RE-entry
Ventricular Flutter:
Explain what it is
Explain what it looks like on an EKG
Ventricular Flutter:
- 250-350 bpm
- Single extremely irritable ventricular automaticity focus
- Back to back identical ventricular depolarization (SINE WAVE pattern)
Torsades De Pointes: “Twisting of the Point”
- Rapid _____ rhythm
- Caused by low _____
- ______ ventricular pumping
- Can degenerate into ____, but often reverts back to sinus rhythm simultaneously
What does it look like on an EKG?
Torsades De Pointes:
- Rapid ventricular rhythm
- Caused by low K, K channel blockers, Long QT syndrome
- No effective ventricular pumping
- Can degenerate into VFib (and Sudden Cardiac Death) but often reverts to sinus rhythm spontaneously
LONG QT SYNDROME:
- What is it?
Long QT Syndrome:
- Genetic disorder, from mutations in ion channels ( like sodium and potassium channels)
- Affects 1 in 3000-5000 people
- Lengthening of the vunerable period
Fibrillation:
- Rapid discharge from ________
- Either ____ or _____ foci
- Many foci firing, no depolarization spreads far
- HR of ____ is hypothetical
- Chambers ______
Fibrillation:
- Rapid discharge from many irritable foci
- Either atrial foci or ventricular foci
- Many foci firing, no depolarization spreads far
- Rate of 350-450 is hypothetical, impossible to get a real rate
- Chambers do not pump at all
Atrial Fib:
Explain what it is
What does it look like on an EKG
What is the big risk with AFib patients
Atrial Fib:
Atrial Fibrillation is really fast foci firing in the atria where it kinda jiggles around, never really pumps
The EKG has a squiggly baseline with QRS complexes that are not at a regular rhythm: irregularly irregular
AFib patients are at a high risk of stroke because the blood pools in the atria and then can coagulate and become clots
VFib:
Explain what it is
What does it look like on an EKG?
VFib:
Quivering Ventricles
VF is a type of cardiac arrest
Death is imminent
Requires immediate defibrillation and CPR
What is Wolf Parkinson White Syndrome?
What does it look like on an EKG?
Wolf Parkinson White Syndrome:
A syndrome in which an extra electrical pathway in the heart causes a rapid heartbeat
The extra electrical pathway is through the bundle of kent and back to the SA node (after going through his perkinje highway)
Common in children
Causes a slurred QRS/slow uptake into QRS complex
Explain what First Degree AV Block is
What does it look like on an EKG?
First Degree AV Block:
essentially a slow AV node
normally PR interval is about 120-200 msec(3-5 small boxes)
longer than that is first degree av block
Explain what Mobitz Type I / Wencebach is
What does it look like on an EKG
Type of second degree av block
pr interval is longer and longer until it drops a beat
Explain what mobitz tpe II is
Mobitz Type II is a type of AV block
It usually is a problem with the His Perkinje System and not the AV node
It is regular intervals of dropped beats
Third Degree Block
The P waves and QRS complexes are independent of one another
Essentially it’s a full AV node block
Describe some of the pharmalogical treatments for arrhthmyias
