Week 10: Cardiac Rhythm Disorders Flashcards
What are the 2 major phases of the cardiac cycle
- Contraciton (Depolarization)
2. Relaxation (repolarization)
Chronotrophy
Heart Rate
Ionotrophy
Contraction Force
Dromotrophy
Conduction Speed
Path of Cardiac Conduction
SA Node –> AV Node –> Bundle of His –> Right and Left Bundle Branch –> Purkinje Fibers
Depolarization
when Na moves into a cell and K moves out
activity causes electrical activity which causes cardiac muscle movement
as one cell depolarizes it makes the next do so as well and causes a chain reaction
Repolarization
occurs when the cell returns to its resting or baseline state
SA Node
Sinus Node / Sinoatrial Node
Main pacemaker of the heart
Stimulates 60-100 BPM through depolarization
Located high in the right atrium
What part of the heart conduction pathway can a right sided MI destroy
the SA node –> this leads to bradycardia and hypotension
Tx when a Right Sided MI occurs
IV fluids!!!
Nitroglycerin
Patient to cath lab
AV Node
atrioventricular Node
Gatekeeper of the heart
fires if the SA node rate is too low at an intrinsic rate of 40-60 BPM
What does the AV node allow for
it allows the atria to contaract and empty by slowing impulses from the SA node
Where is the AV node located
small group of cells in the lower right atrium
Bundle of HIS
short bundle of fibers at the bottom of teh AV node
they are specialized electrical cells that travel in the septum and spread to both sides of the heart in both ventricles
leads into the bundle branches
The Bundle Branches
Left and Right
Rapidly conduct impulses to the left and right ventricles after the Bundle of HIS
The Purkinje Fibers
Terminal point in the conduction system in the ventricles
they are hair like fibers spreading out from the bundle branches along the endocardial surface of the ventricles
rapidly conduct the impulse to the ventricular cells
The Purkinje Fibers are capable of causing impulses at ___-___ BPM
20-40
P Wave
a normally small smooth and rounded bump at the start of the impulse
indicated atrial contraction / atrial depolarization
PR Interval
Conduction from the atrium to Purkinje fibers depolarizing
Measured from start of P wave to the tip of the R
How long is the PRI usually
normally less than 1 large (or 5 small) blocks so less than 0.2 seconds
So usually 0.12-.20 seconds
Each small box on the EKG is ___ s
0.04 seconds
Each large box on the EKG is ___ s
0.2 seconds
5 of the large boxes (25 small boxes) on the EKG is ___ s
1 second
QRS Complex
Occurs with ventricular contraction/depolarization
Q is the first down, R is the first up, and S is the negative deflection after r
Usually less than 2.5 small boxes (0.1 s) –> 0.06-0.1 s
T Wave
Follows the QRS
Indicated ventricular repolarization
heart resting period
What wave indicates a vulnerable period of the heart where if there is an issue something lethal can occur
T Wave
Different deflections from baseline of the PQRS complex indicates..
different views or LEADS of hearts conduction patterns (lead 2-3 may look different)
When Assessing EKGs it is important to look at what 2 things
- Rhythm - regular/irregular - the origin of beat
2. Rate - number of ventricular contractions per minute
We should check the EKG first to see if there is a…
P wave
We can check rhythm by
measuring distance between P-P2 R-R2 waves and comparing peaks
What are the 3 methods of calculating rate off an EKG
- # Small boxes Between QRS Complexes / 1500
- # Large boxes between QRS complexes / 300
- 6 Second Method - number of peaks x 10
What are the things to ask when evaluating the P wave and PR Interval
Does the rhythm originate in the atrium
Are P waves regular
Are P waves followed by QRS
Is the Pr normal .12-.2 in length or is it longer than .2
What are the things to ask when evaluating QRS complex
Is it normal duration of .06-.1 or is it higher
Do the QRS complexes look the same - wide ones can indicate ventricular arrhythmias
What are the thigns to ask when evaluating ST Segments
Is T Wave height less than 1/2 the QRS height
Is ST elevation above or depression below isometric line - indicates ischemic changes or MI
Raised ST increases threshold which can…
cause a heart attack
What are some other unusual findings on EKGs to see
ST Depression
Q Waves - scar from MI
Ectopic Beats - originate from abnormal pathways
Abnormal Herat Rhythms
Sinus rhythm
normal rhythm
Premature Rhythm
complex earlier than expected
Compensatory rhythm
pause in the beat occurring after a premature beat
Junctional rhythm
at or below AV node, above ventricle
Normal Sinus Rhythm
Rate 60-100 BPM
Regular R to R Interval
Normal PR Interval
Sinus Bradycardia
Rate < 60 BPM
Regular R to R interval
Normal PR Interval
P Wave
Beats are initiated in SA node
Sinus Tachycardia
Rate >100 BPM
Regular R to R Interval
P Wave Present
Normal PR Interval
Beat Initiated in SA Node
Sinus Arrhythmia on EKG
Rate 60-100 BPM
IRREGULAR R-R INTEVAL
P wave present and Normal PRI
Beat initiated in SA Node
BPM increases with inhalation and decreases with exhalation!!!
Dysrhythmias
disorders of formation or conduction (or both) of electrical impulses within heart
potentially alters blood flow, causes hemodynamic changes
Dysrhythmias can cause disturbances of…
rate
rhythm
both rate and rhythm
Dysrhythmias are diagnosed by …
analysis of electrographic waveform
Dysrhythmias can be ___ or ___ in origin
supraventricular (above - SA/AV node)
Ventricular (bundle branches/perkinje)
What are the 3 most common Supraventricular Rhythms
Junctional Rhythms
A Fib
A Flutter
What are the 3 most common Ventricular Rhythms
PVC
VT
VF
What is more deadly supraventricular or ventricular rhythms?
Ventricular Rhythms
Premature Atrial Contraction (PAC)
Abnormal P Wave that comes early and fuses with T wave
There is then a pause after it occurs
Lots of people have this occur
What can cause PAC
caffeine
Nicotine
stress
ischemia (big problem)(
Atrial Fibrillation
Rate: 400-600 BPM atrial; Ventricular rate varies but can be high as 110-160
R to R is irregular
No P WAVES!!!
QRS appears normal usually
What is the most common rhythm seen next to normal sinus rhythm (NSR)
A fib
If A Fib has a rapid ventricular rate as well…
this may cause reduced cardiac output
A Fib may lead to …
Mural Thrombi
In A Fib what is lost and can lead to heart failure
atrial kick
Tx for A Fib
Watch for CO (BP, UO, LOC, Color)
Meds - variety used to control rate or restore normal rhythm (digozin, verapamil, beta blockers)
ASA - anticoagulants
Watchman
Cardioversion or pacemaker may be necessary if unstable
Watchman
Device that is like a coffee filter surgically implanted into the inferior vena cava/major vessel/vessel that catches the clots if you were prone to clots
Atrial Flutter
Regular R-R Rhythm!!!
Similar to A Fib but has no P Waves - rate is still high (fast though)
Saw Tooth Pattern P Waves
Atrial rate usually 200-300 and ventricular rate usually normal
In A Flutter the patient shows s/s of
Decreased CO
What may form in A Flutter
Mural Thrombi
Persistent atrial flutter converts…
to sinus rhythm or atrial fib by itself or in response to meds
What is A Flutter treatment like
A Fib Treatment
Junctional Rhythms
Rate 40-60
R-R Regular
No P Wave or Inverted P Wave
Occurs above ventricle and at the AV node or Bundle of HIS
What is Junctional Rhythm like
treat underlying causes: pacemaker, drug toxicity
tx s/s!
Where is the junctional rhythm issue occurring?
Below SA Node but above the ventricle
PVC (Premature Ventricular Complexes)
Normal QRS, Flipped T Wave - looks like wide bizarre QRS complexes that come in early and have a pause after
What may cause PVCs to happen
Premature Depolarization in Ventricular Myocardium:
Hypoxia Myocardial Ischemia Hypokalemia Acidosis Exercise Increased Digoxin Level Increase with Aging More common with CHD
Not dangerou w/ normal hearts; higher mortality with heart disease
PVCs may indicate what serious problems occurring
MI
Digoxin Toxicity
Hypoxia
Electrolyte Imbalance (Potassium)
Associated with Acute MI
PVC are dangerous when…
- more than 6 per minute
- its near a T wave
- In couplets or triplets or more in a row
- Multifocal
- when associated with acute MI
Treatments for PVC
Acute - IV Lidocaine
Treat Cause: Hypokalemia
Other agents for long term control ex: Cortisol - amiodarone (push slow)
If ischemic problem - nitrates (vasodilates) and O2
Bigeminy
normal sinus beat interspersed with PVC
Trigeminy
2 sinus beats interpersed with PVC
Causes of Bigeminy/Trigeminy
MI, CHF, Digoxin Toxicity
Treatments for Bigeminy and Trigeminy PVC
Long term problems: Antiarrhythmics, Procan SR, Pronestyl
V-Tach
Ventricular Tachycardia
No P Waves
Wide Bizarre QRS Complex - VTach Mountains
Ventricular Rate of 150-200+ BPM
rhythm - Regular
How lethal is V Tach
can be very lethal - pulseless V Tach even needs defibrillation or CPR as it means no perfusion (its just electrical activity)
What is the first thing to do when a patient enters V Tach
check patient and talk to them and feel for a pulse
Causes for V Tach
similar to PVCs but this is considered more dangerous because of decreased cardiac output and its ability to degenrate further
What is V Tach called based on if its 30 seconds or longer
If less than 30 seconds = Nonsustained VT
If more than 30 sec = Sustained VT
V Tach is a precursor to…
ventricular fibrillation
What can occur with V Tach for the patient
inadequate perfusion leading to loss of consciousness
V Tach Treatment
IV lidocaine or amiodarone
Cardioversion (Sync Shock)
Treat Underlying Cause: MI, K Imbalance, Chornic - may need implantable defibrillator
What can be assumed is low if K is low
Magnesium
Ventricular Fibrillation
No P Waves, No QRS Complex, Rhythm is Irregular and Chaotic, rate is rapid and uncoordinated and ineffecteive
No CO = No pulse
Fatal if not treated
During V Fib what will be absent
A pulse is definitely absent
V Fib is ___ if not treated
Fatal
V Fib is a cause of…
sudden cardiac death
Treatment of V Fib
Defibrillation (Immediate!) and or CPR!!!!!!!!
Use ACLS protocols for defibrillation
Antiarrhythmic drugs may be used as well
Cardioversion and Defibrillation
treat tachydysrhythmias by delivering electrical current that depolarizes critical mass of myocardial cells - when cells repolarize, sinus node usually able to recapture role as heart pacemaker
What happens in Cardioversion
current delivery synchronized with the patients ECG
What happens in defibrillation
current delivery is not synchornized with the patient EKG
you often have to do this first when you cannot sync and then do cardioversion after
Safety Measures for Cardioversion and Defibrillation
Assure good contact between skin, pads, or paddles
PLace paddles so they do not touch bedding or clothing and are not near mediation patches or o2 flow
If cardioverting turn sync on
if defibrillating turn sync off
no wet or metal surface
dont touch patient when attached
A user of Defibrillation must be ___ ____
ACLS trained
What has to be used when a user is not ACLS certified
AED - Automatic Defibrillation
Asystole
No rate
No Rhythm
P waves can be present if SA or AV is fxning
QRS Complex gone
No CO, Pulse, very poor prognosis
NEEDS IMMEDIANT TREATMENT
Check pt first then monitor
No pulse here
When do you shock in asystole
never - thats only done in movies
theres nothign to shock
Tx for Aystole
Must be Immediate:
EP
Atropine
Pacemaker (External, Temp internal, CPR (do this first))
Pacemaker
electronic device that provides electrical stimuli to heart muscle
Types of Pacemakers
Permanent
Temporary
What situations indicate Pacemakers
sick sinus syndrome
heart blocks
post op cardiac surgery
post MI with heart block
Heart Block
dissociation between SA node to AV to bundle branches
communication between top or bottom of the heart
What shows a pacemaker is in use on the EKG
a pacemaker spike before the QRS (and a slightly wider QRS)
ICD Implantable Defibrillators
Senses and converts V Tach and V Fib
Similar to a pacemaker with similar teaching
Medic alert bracelet
Battery check every 6 months
typically sits on left side
Complications of Pacemaker/Defibrillator Use
infection
bleeding or hematoma formation
dislocation of lead
skeletal muscle or phrenic nerve stimulation
cardiac tamponade
malfunction of pacemaker/defibrillator
Cardiac Tamponade
Bleeding into the pericardial sac leading to tamponade which restricts the heart and can lead to cardiogenic shock
Nursing Interventions for pts with Pacemakers
Monitor cardiac rhythm - sensing and capturing
Note pacemaker rate, MA (milliamps), and Mode
Patient response to pacing
Care of the patient with an ICD - assessment
device function : ECG
cardiac output
hemodynamic stability
incision site
coping
patient and family knowledge
PAIN
Patient teaching on Pacers and Defibrillators should involve
regular pacemaker monitoring
taking heart rate
avoiding magnets like in an MRI
wearing medi bracelet or having the card
Invasive Methods to Diagnose and Treat Recurrent Dysrhythmias
Electrophysiologic Studies (EPS)
Cariac Conduction Surgery: Maze Procedure or Catheter Ablation Therapy
Ablation
An a fib treatment
burning off or ablating the area causing the A Fib
Potential s/s of Cardiovascular Problems
Fatigue
Fluid Retention
Irregular Heartbeat
Dyspnea
Pain
Syncope or Near Syncope
Leg Pain
What is included in a cardiac health assessment
medication nutrition elmiination activity and exercise sleep adn rest self perception and self concept roles and relationships sexuality and reproduction coping and stress tolerance prevention strategies
Important Risk Factors for CV Disease
elevated serum lipid
HTN
tobacco use (Smoking and chewing)
sedentary lifestyle
obesity DM II
stressful lifestyle
Why do we keep an arm at the level of the heart during BP
if elevated it lowers pressure
if dependent it raises pressure
Pulse Pressure
Systolic - Diastolic
Not significant alone but in the wider picture it is
usually 30-40 mmHg
Drop can indicate heart failure, shock, hypovolemia
Increase seen with increased stroke volume likeatherosclerosis anemia hyperthyroid or pregnancy
Normal Response to Postural BP
transient increase of 5-20 BPM
drop in systolic of <10 mmHg
AND
increase in diastolic of 5 mmHg
Orthostatic or Postural hypotension can be accompanied by
dizziness
lightheadedness
syncope
3 most common causes of postural hypotension
intravascular volume depletion
inadequate vasoconstrictor mechanisms
autonomic insufficiency
When does Orthostatic BP (orthostasis) occur
when there is a drop in systolic of 20 mmHg or more, a drop in diastolic of at least 10 mmHg and a pulse rise greater than or equal to 20 bpm
Is posutral BP change from lying to sitting food enough for orthostasis diagnosis?
no but it can be a screening test
Allen Test
occlusion of radial and ulnar pulse test
Amplitude Scale
Absent = 0 = Need doppler
Diminished = +1
Normal = +2
Mod Increased = +3
Markedly Increased = +4
Other than pulses what other pulse should we check
the abdomen aorta for aneurysms
Pulsus Alterans
regular alteration of weak and strong beats w.o changes in cycle length
from heart failure or pericardial effusion
Bruits
a blowing sound that occurs with turbulent blood flow - suggests partial obstruction to blood flow
a palpable thrill
arteries are normally silent is why this is bad
Jugular Venous Pulse
can give information about right hear hemodynamics
while in semi fowlers you observe pulsations of right internal jugular vein and the measure of cm above sternal angle - if above 3 cm thats abnormal
may indicate heart failure or fluid overload
Where are the Aortic, Pulmonic, Tricuspid, and Mitral areas
Aortic - 2nd ICS on RSB
Pulmonic - 2nd ICS on LSB
Tricuspid - 4th ICS on LSB
Mitral - 5th ICS on LSB
Stethoscope diaphragm for ___ pitch sounds like ___ and ____
high; S1 and S2
Stethoscope bell for ___ pitched sounds like ___ and ___ and ____
low; S3 S4 murmurs
S1
first heart sound
closure of mitral and tricuspid valves
onset of systole
loudest at apex
S2
second heart sound
closure of aortic and pulmonic valves
beginning of diastole
loudest over pulmonic area
S3
third heart sound
physiologically normal in children, fit athletes and well exercised
pathologic in new onset or found after age 40
sounds like Lub Dup Ta
Gallop Rhythm / Sloshing In
S4
least common fourth heart sound
HTN and stiff walls from cardiovascular damage causes this
Ta Lub Dup - precedes S1
Best heart with bell like S3
Can mean aortic stenosis scarring or HTN
Murmurs
Are sound produced by abnormal turbulance:
bruit within a vessel
murmur across a valve
location of murmur tells what valve is troubles
can sound like whoosh, click, mechanical
Murmurs are classified by…
timing in cardiac cycle
pitch (low medium high)
location - apex, sternum
quality - soft blowing harsh mechanical
duration - throughout cycle or at the beginning
intensity - scale of I to VI
If a murmur is heard at apex between S1 and S2 then it is a ___ murmur and PROBABLY is ____
systolic; mitral valve
Cardiac Markers
CPK - creatine kinase
CRP
Troponin T and I
Homocysteine
What level should HDL be
> 35
What does LDL <160, 130, and 100 mean
<160 - primary prevention, 1 or no risk factors
<130 primary prevention, 2 or more risk factors
<100 secondary prevention, person with known CAD
Medications for cholesterol are only used for…
high levels of LDL cholesterol
A client with angina asks the nurse “What information does the EKG
provide?” The nurse would respond that the EKG primarily gives information
about the:
- Electrical conduction of the myocardium.
- Oxygenation and perfusion of the heart
- Contractile status of the ventricles
- Physical integrity of the heart muscle.
- electrical conduction of the myocardium
Which of the following are tests used to specifically evaluate the function of the heart? (Select all that apply) 1. EEG 2. TEE 3. BUN 4. CK-MM fractions 5. Holter monitor 6. Cardiac catheterization
- TEE
- Holter Monitor
- Cardiac Catheterization
When discussing the patient's elevated LDL and lowered HDL levels, the patient shows an understanding of the significance of these levels by the statement:
A. “Increased LDL and decreased HDL increase my risk of coronary artery disease.” B. “Increased LDL and decreased HDL decrease my risk of coronary artery disease.” C. “The decreased HDL level will increase the amount of cholesterol moved away from the artery walls.” D. “The increased LDL will decrease the amount of cholesterol deposited on the artery walls.”
A. Increased LDL adn decreased HDL increase my risk of CAD
In preparation for a transesophageal
echocardiography, the nurse must:
A. Have the patient drink 1 liter of water
before the test.
B. Heavily sedate the patient.
C. Inform patient that blood pressure (BP)
and electrocardiogram (ECG) will be
monitored throughout the test.
D. Inform the patient that an access line
will be initiated in the femoral artery.
C. Inform patient that blood pressure (BP)
and electrocardiogram (ECG) will be
monitored throughout the test.
Which of the following indicates a positive result of an exercise stress test? A. Chest pain B. Drop in BP and pulse C. Target heart rate reached D. ST segment depression
A. Chest Pain
In teaching the client to avoid orthostatic
hypotension, the nurse should emphasize
which of the following instructions? (select all
that apply).
1. Plan regular times for taking medications
2. Arise slowly from bed
3. Avoid standing still for long periods
4. Avoid excessive alcohol intake
5. Avoid Hot baths
- Arise slowly from bed
3. Avoid standing still for long periods
