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Perfusion 1 - Dysrhythmias
Terms in this set (95)
Causes of altered conduction
•Congenital or anatomical defects
•Lack of oxygen: ACS, hypoxemia, anemia
•Metabolic derangements: acidosis, hypo/hyperkalemia, hypo/hypernatremia, hypo/hypercalcemia, hypomagnesaemia
•Drugs: stimulants, sedatives, nicotine, caffeine
•Sympathetic over-stimulation...even fear
•Just because...only the Shadow knows
cardiac conduction system
sinoatrial (SA) node- sends impulse to atria
atrioventricular (AV) node- delays impulse to ventricles
bundle of His (AV bundle)
Purkinje fibers- distributes electrical impulse starting at the apex of the heart and moving upwards to pump upwards
Electrical vs Mechanical activity of heart
-Thousands of electrical impulses stimulate all the cardiac cells in a coordinated wave motion. Each myocyte is joined into the next, forming bands. The bands join together into sheaths making the muscle of the heart. 1st electrical.
-When all the cells are stimulated, the mechanical event, contraction of the muscle unit, occurs. When these muscle cells are no longer electrically stimulated, the muscle relaxes. 2nd mechanical.
Inherent rates of each node
•SA node 60 - 100 BPM
•AV node 40- 60 BPM
•Ventricles/purkinge fibers 20 - 40 BPM
Only particular cells of the heart can be a pacemaker. (T/F)
False. Any cardiac cell can be a pacemaker if inappropriately stimulated by electrolytes, ischemia, or if it does not perceive a stimulus from the pacemaker cells above it.
Electrical events of the cardiac cycle
- P wave (atrial depolarization)
- P-Q OR P-R Segment
(conduction thru AV node and AV bundle)
- Atria contract
- Q wave
- R wave
- S wave
- S-T segment (ventricles contract)
- T wave (ventricular repolarization)
The P wave
-First wave in the cardiac cycle representing atria depolarization.
-It starts when the SA node fires.
The QRS complex
-Represents ventricular depolarization
-Composed of 2 or more waves
>Q wave - can be absent or present
>R wave - the initial wave of the QRS if the Q wave is not present
-Should be <0.12 sec
The T wave
-Represents ventricular repolarization
-Occurs after the QRS and should be in the same direction as the QRS
-This is the period where the heart is gearing itself up for the next electrical impulse and contraction.
ECG graph paper
-Horizontal lines represent time and vertical lines represent amplitude
--1 small box= 0.04 seconds
-1 Large box = 0.2 sec
-5 Large box = 1 sec
ECG Rhythm Analysis
Determine heart rate
Determine heart rhythm
Analyze P waves
Measure the PR interval
Measure the QRS duration
Are the QRS complexes narrow or wide
Interpret the cardiac rhythm
premature ventricular contraction (PVC)
-Come from ectopic focus in ventricles
-Wide and distorted shape compared with QRS
-Premature occurrence of a QRS
Pathophysiology of PVC
-Irritable foci in the ventricle wants to take over as pacemaker
-Organized cells want SA node to be pacemaker
-Irritable foci in ventricle continues to take over, this leads to decrease CO
-The PVC may or may not have an associated pulse that gets perfused
>Pulse can be weak, dampened, or not produced.
Causes of PVC
-Chemical changes of imbalances in the body
-Certain medication (aminophylline, epinephrine, isoproterenol - asthma)
-Alcohol or illegal drugs
-Increased levels of adrenaline in the body that may be caused by caffeine, tobacco, exercise, energy drinks, or anxiety
-CAD, congenital heart disease, hypertension, HF
How many PVCs in a row require treatment?
Six of more per minute or three or more in a row.
Treatment of PVCs
-Most people don't need treatment
-Always check if symptomatic
-Lifestyle changes (tobacco, caffeine)
-Oxygen for hypoxia
-Amiodarone 150 mg IVSP over 10 minutes followed by drip (if it works)
-Lidocaine, beta blockers
Radiofrequency catheter ablation
radiofrequency catheter ablation
To treat certain cardiac arrhythmias, radiofrequency energy is delivered from the tip of a catheter inserted through a blood vessel into the heart. The treatment destroys or ablates the tissue causing the arrhythmia.
every other beat is a PVC
-Wide and bizarre QRS
-No P wave
-More than one shape
>Means the heart has more than one place that is irritable
occur in pairs
every third beat is a PVC
three or more PVC's occur in a row; also considered ventricular tachycardia
R on T phenomenon
-A PVC whose R wave falls on the T wave of the preceding complex
-Dangerous due to PVC firing during the refractory phase of ventricular repolarization
>Excitability of heart cells increase during this time, and risk for PVC to start VT or VF is great
Torsades de pointes
-Polymorphic ventricular tachycardia, characterized by shifting sinusoidal waveforms on ECG; can progress to ventricular fibrillation.
-Treatment includes magnesium sulfate.
Torsades de pointes causes
-Prolonged QT interval
a very rapid heartbeat that begins within the ventricles
Causes of VT
-Early or late complication of myocardial infarction
-Valvular heart disease
-Changes in blood chemistry (low or high potassium or magnesium)
-Changes in pH
-Lack of oxygen
VT treatment - Long Term and Emergent
-Dependent on symptoms and type of disorder
Long term treatment
-Implantable cardioverter defibrillator (ICD)
-Defibrillation or cardioversion
-Anti-arrhythmic meds (IV amiodarone, lidocaine, procainamide)
Monomorphic vs Polymorphic V Tach
Monomorphic ventricular tachycardia demonstrates a stable QRS morphology from beat to beat while polymorphic ventricular tachycardia has changing or multiform QRS variance from beat to beat.
Treatment of VT with a pulse - Stable and Unstable pt
-Amiodarone 150 mg over 10 minutes
>Start at 100 joules
-The pt will soon become pulseless, then follow the pulseless Vtach/Vfib algorithm
Ventricular fibrillation (V-fib)
-Is rapid, disorganized depolarization of the ventricles
-Is a life-threatening dysrhythmia
-The heart's electrical activity becomes disordered
-The heart's lower (pumping) chambers contract in a rapid, unsynchronized way
-The ventricles "fibrillate" rather than beat
-The heart pumps little or no blood
-Collapse and sudden cardiac arrest follows - MEDICAL EMERGENCY
-Common: After MI. Lack of oxygen to muscle tissues
-Electrolyte imbalances: potassium, magnesium, calcium, phosphorus
-Drugs: cocaine, digitalis
-Same as VT causes
Minutes to Defibrillation: Chance of survival from cardiac arrest
1 minute - 90%
Drops 10% for each additional minute
coarse ventricular fibrillation
VF with fibrillatory waves greater than 3 mm in height
fine ventricular fibrillation
Ventricular fibrillation in which there are very small deflections of the baseline
Cardiac Arrest Algorithm for Vtach/Vfib
-CPR 2 minutes
-If rhythm still shockable then shock
-CPR 2 minutes
>Epinephrine every 3-5 minutes
-CPR 2 MIN
>Amiodarone or lidocaine
Cardiac Arrest Algorithm - Asystole/PEA
-CPR 2 MIN
>Epinephrine every 3-5 minutes
-CPR 2 MIN
>Treat reversible causes
epinephrine, norepinephrine, dopamine
•Adrenergics are drugs with effects that are similar to or mimic the effects of the SNS neurotransmitters norepinephrine, epinephrine, and dopamine. These neurotransmitters are known as catecholamines.
•Chronotropic and ionotropic effects: aim is to produce a cardiac output
Catecholamines produce a sympathomimetic response. They are either endogenous substances such as epinephrine, norepinephrine, and dopamine or synthetic substances such as __________________________________.
dobutamine and phenylephrine.
_________________________ markedly prolongs the action potential duration and the effective refractory period in all cardiac tissues. Besides exerting these dramatic effects, it is also known to block both the alpha-and beta-adrenergic receptors of the sympathetic nervous system
Amiodarone (Cordarone, Pacerone)
•Class III anti-dysrhythmic
Clinically it is one of the most effective antidysrhythmic drugs for controlling supraventricular and ventricular dysrhythmias. It is indicated for the management of sustained VT, ventricular fibrillation, and nonsustained VT. It is reported to be effective in 40% to 60% of all patients with VT.
•prototypical Ib anti-arrhytmic drug. It is effective for the treatment of ventricular dysrhythmias.
•Effects the heart by making it difficult for the ventricles to develop a dysrhythmia. This action is known as raising the ventricular fibrillation threshold. It occurs by decreasing the sensitivity of the cardiac cell membrane to impulses and decreasing the cell's ability to depolarize on its own (decreasing automaticity). Many of these effects are accomplished by blocking the fast sodium channels.
Post-Cardiac Arrest Care
1) Optimize ventilation and oxygenation
2) Treat hypotension
-12 lead EKG
Consider emergent cardiac intervention if:
-Unstable cardiogenic shock
-Mechanical circulatory support requires
3) Follow commands (if no, therapeutic hypothermia)
4) Advanced critical care
Once the patient resumes a perfusing rhythm and somewhat stable, then plan to do what?
-Apply Target Temperature Management (TTM)
-Place on meds: anti arrhythmic drugs
-Insert ICD: constantly monitors heart rhythm.
-Perform coronary angioplasty and stent
-Currently, advance cardiac life support (ACLS) guildelines state that a temperature between 33-36 C is recommended for at least 24 hours after achieving the target temperature.
-Intubated pts with treatment initiated within 6 hours after cardiac arrest.
-Pts able to maintain a systolic BP above 90 w/ or w/o pressors
-Pts in a coma at the time of cooling
>There is a protocol that outlines the nurses role during TTM
Interventions seen with TTM protocols
-Obtain 12 lead ECG after ROSC to evaluate ST elevation
-Monitor for dysrhythmia (most commonly bradycardia) associated with hypothermia
-If life-threatening dysrhythmia arises and persists, or hemodynamic instability or bleeding develops, d/c cooling and rewarm pt
-Check skin Q2-6 hours for thermal injury
-Regularly check pts temp w/ secondary temp device
-Maintain 02 over 94%
-Do not provide nutrition during initiation, maintenance, or rewarming phases of therapy.
Why should you be careful during TTM to lower physical stimuli such as jostling, chest compressions, and endotracheal intubation?
In hypothermic pt, even when purposeful, physical stimuli can cause ventricular fibrillation in a cold heart that is functioning effectively.
QRS-complex: wide and bizarre
>AKA: DYING HEART
Causes of IVR
End stage cardiac disease
-A state of no cardiac electrical activity, hence no contractions of the myocardium and no cardiac output or blood flow
-Some activity may be present in the atria so there might be p wave present
Asystole causes - Hs and Ts
-Any condition that may cause inadequate blood flow
-Hypoxia, hypovolemia, hydrogen ion (acidosis), hyper/hypokalemia, hypoglycemia, hypothermia
-Toxins, tamponade (cardiac), tension pneumothorax, thrombosis (coronary and pulmonary, trauma
Pulseless Electrical Activity (PEA)
-Heart rhythm is observed on the ECG but not producing pulse
-Many be ANY rhythm, usually slow and irregular, with NO ASSOCIATED PULSE
-TREATED AS ASYSTOLE
-Usually an end stage dysrhythmia
implantable cardioverter defibrillator (ICD)
-Small electrical device installed inside the chest to prevent sudden death from cardiac arrest due to abnormally fast heart rhythms (vtach)
-Newer-generation ICDs may have dual function which included the ability to serve as a pacemaker
Many pts with ICDs have what issues after implantation?
Psychological stress due to lifestyle changes and receiving a shock at any time
Education for pts with ICDs
If they feel shock they should go to ED immediately
If ICD is not an option, what is?
LifeVest external defibrillator
First degree heart block
-A conduction delay through the AV node is slow
-Characteristics of NSR but PR interval is >0.20 second
causes of first degree AV block
-Drugs: digoxin, beta blocker, calcium channel blockers
Second degree heart block Type I
-AKA Wenkebach or Mobitz 1
-Longer, longer dropped beat
Mobitz I is associated with what?
Second Degree Heart Block Type II
-AKA Mobitz II
-Intermittent failure of the AV node
-PR interval is constant but there may not be a QRS for each P wave (sometimes the rhythm will have a pattern)
Mobitz II is associated with what? May require what?
-Associated with anterior MI and high rate of mortality
-May require pacer insertion
3rd degree AV block
-Complete heart block
-Atrial impulses are completely blocked at the AV node
>Atrial impulses fail to reach the ventricles
-Results in two different paces controlling the atria and ventricles
>QRS appearance based on which pacer is controlling the ventricles (junction or ventricles)
Causes of third degree AV block
-Severe heart disease, including: CAD, MI, myocarditis, cardiomyopathy, age-related
-Some systemic diseases such as amyloidosis and progressive systemic sclerosis (scleroderma)
-Drugs: Digoxin, Beta blockers, CCB
Adult Bradycardia Algorithm
>O2 if needed
>12 lead ECG
>No - Monitor
1. Atropine (1 mg bolus repeat Q3-5MIN up to 3 mg)
>If ineffective then transcutaneous pacing and/or dopamine infusion or Epinephrine infusion
2. Consider expert consultation and transvenous pacing
-IV form: increase HR and improves the AV conduction by blocking the parasympathetic influences on the heart.
How a pacemaker works
-They have one to three wires that are each placed in different chambers of the heart
-The wires in a biventricular pacemaker carry pulses from the generator to an atrium and both ventricles. The pulses help coordinate electrical signaling between the two ventricles. This types of pacemaker also is called cardiac resynchronization therapy (CRT) device.
Single chamber pacemaker
-The wires in a single-chamber pacemaker usually carry pulses from the generator to the right ventricle
dual chamber pacemaker
-The wires in a dual-chamber pacemaker carry pulses from the generator to the right atrium and right ventricle. The pulses help coordinate the timing of these two chambers contractions.
What can pacemakers do?
-Speed up a slow heart rhythm
-Help control an abnormal or fast heart rhythm
-Assist the ventricles if the atria are contracting abnormally
-Coordinate electrical signaling between the upper and lower chambers of the heart
-Prevent dangerous arrhythmias causes by a disorder called long QT syndrome
If pacer is set at 70 BPM and heart gets up to 80, what will happen?
Nothing, the pacer would not fire. If transcutaneous you want to make sure they don't override the set rate.
Causes for temporary pacemakers
-Chest and cardiac trauma associated with either temporary SA node or AV node dysfunction
-Metabolic and electrolyte
-Drug induced brady-arrhythmia
External Transcutaneous Pacing
-Usually used when emergent, short-term pacing is needed to stabilize patient until another pacing method can be initiated
-Located on the crash cart
-Place pads on sternum and posterior chest or around the apex and base of the heart anteriorly
-Must have defibrillator leads on
Things to remember with temporary pacing
-If hairy chest, clip hair instead of shave to avoid nicks
-Set pacemaker settings as prescribed or follow P&P for the institution
-May need analgesics or sedatives to minimized pain
-Patient and family teaching
-Goes into endocardium and from scar tissue which allows to stay in place
-Wide complex due to stimulation of ventricles
-Should carry a card in wallet with type and serial number of pacemaker;
report redness and tenderness - s/s infection
-Will need to be changed eventually to change battery
Demand Mode - Pacemaker
-The pacer only delivers paced pulses when the patient's heart rate is lower than the selected pacing rate
-All permanent pacers with a lead wire in the ventricle are this type to avoid pacing during ventricular repolarization
Fixed mode - Pacemaker
-The pacer delivers paced pulses at the selected rate
-Set rate must be higher than the patient's actual heart rate to avoid competition
Overdrive mode - Pacemaker
-Anti-bradycardia and anti-tachycardia pacing
Post Op care - Pacemaker
-Check pacer function
Identification - Pacemaker
- ALL patients with a pacemaker are supposed to carry a card that tells what brand and type of pacemaker they have
-Most people do have these cards so check them out FIRST!
Patient education Post Surgery- Pacemaker
-Carry ID card at all times.
>Medic alert bracelets also available
-Notify doctor for fever of 100 degrees or higher that lasts for a few days
-A slight bulge will be felt at the pacemaker site
-Please notify doctor if you notice the following at the site:
>A bruise that does not go away
>Soreness or yellow, green, or brown drainage from the site
>Any swelling from the site
-Avoid activity that involves rough contact with site
-Doctor will instruct when you may resume driving
-Usual are movement is allowed but avoid lifting your arm over your head on the pacemaker side or lifting over 10 pounds for 4 weeks.
Patient education - General for Pacemaker
-Advise dentist of other medical personnel you see that you have a pacemaker.
-If you require MRI, discuss with MD
-Avoid working with radar, strong magnets, or powerful electric devices, antitheft devices.
>If a powerful device makes you dizzy, step away from device
-Grounded home electrical appliances have little or no effect on pacemakers
-You will need your ID card if you go through metal detector, such as at airport
-The goal is to avoid electromagnetic fields
AV paced rhythm
spike before P and QRS
Failure to Fire Pacemaker
-If temporary pacemaker, check the connections, increase the milliamps to result in capture or increase sensitivity
-If permanent, the nurse would want to have transcutaneous pads on just in case.
failure to sense (pacemaker)
Pacemaker fails to sense naturally occurring electrical stimulation and fires inappropriately.
-Temporary, increase sensitivity
-Permanent, it would need to be interrogated (pacer company does this) and depending on the response of the client they may need to be transcutaneous paced.
Failure to capture (pacemaker)
Failure to capture means that the ventricles fail to response to the pacemaker impulse. On an EKG tracing, the pacemaker spike will appear but it will not be followed by a QRS complex.
-You should increase milliamps or mA.
bundle branch block (BBB)
Occurs when the electrical impulse is blocked from traveling down the bundle of His or bundle branches. Results in the ventricles beating at a different rate than the atria. Also called a heart block.
Left Bundle Branch Block
A Q wave is seen instead of an R wave in MCL1
-QRS greater than 0.12
-Wide S wave in leads V1 and V2
-Wide R wave in V5 and V6.
-Can mean new onset MI in that area.
Right Bundle Branch Block
Rabbit ears in V1 and MCL1 and widening of QRS as well as ST depression and T wave inversion.
In 3rd degree heart block, the SA node generates impulses but those impulses do not go to the ventricles. Therefore, the atrial and ventricles are independent.*
In 2nd degree, type 2 (Mobitz II), the p-waves (atrial rate) are usually regular while the ventricle rate is irregular. In addition, this pattern tends to be CYCLIC.*
In 1st degree AV heart block, the p-waves are always accompanied by the QRS complex.*
2nd Degree Type 2 Heart Blocks are sometimes called Wenckebach Heart Blocks.*
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