Week 3 - Cardiac Dysrhythmias Flashcards
what are dysrhytmias
- abnormal cardiac rhythmns
describe how to electrical conduction system works
- SA node (upper RA) –> AV node –> bundle of His –> right and left bundle branches –> perkinje fibers
what does the cardiac impulse in the SA node cause
- atria contract
what is the function of the AV node
- delays the passage of elecrical impulses
= ensure the atria have ejected all blood, give ventricles time to fill
what is an ECG
- graphic tracing of the electrical impulses produced the heart
what is the pacemaker of the heart
SA node
what does the P wave on an ECG represent
- atrial contraction (deporalization)
what does the P-R segment represent on an EK
- time it takes for the impulse to travel from the SA node to the bundle of his, bundle branches,and purkinje fibers to a point immediately before ventricular contarction
what does the QRS complex represent
- firing of the AV node
& ventricular depolarization (conraction)
what does the S-T segment represent
- time between ventricular depolarization and repolarization
what does the T wave represent
- ventricular repolarization before ventricular diastole
what can cause dysrhythmias
- disorders of impulse formation
what are some common cardiac causes of dysrhythmias (6)
- CHF
- MI
- myocardial cell degeneration
- conduction defects
- accessory pathways
- hypertrophy of heart muscle
what are some other conditions that can cause dysrhythmias (13)
- acid-base imbalance
- alcohol
- coffee, tea
- CT disorders
- drug effects, toxicity
- electric shock
- electrolyte imbalances
- hypoxia
- shock
- emotional shock
- metabolic conditions
- near-drowning
- poisoning
what is a high priority with management of dysrhythmias
- determination of rhtyhmn by cardiac monitoring
what can be done to evaluate cardiac dysrhytmias (5)
- continuous ECG monitoring
- electrophysiological test (invasive)
- holter monitoring
- event recorder monitoring
- exercise treadmill testing
what is an electrophysiological test
- involves introducing several electrode catheters transvenously thru the femoral vein to the R side of the heart
- then electrical stimulation is done to induce dysrhythmia
what may be required w electrophysiological test
- immediate cardioversion or defibrillation bc it may induce serious dysrhythmias
what is a holter monitor
- device that record the ECG while the pt is ambulatory
- can record heart rhythmns for 24-48 hrs
what must a pt do when having a holter monitor
- keep diary where actvities and symptoms are recorded
what is holter monitor useful for (3)
- detecting signif dysrhythmias
- evaluates the effects of drugs during a pts normal normal activities
- can detect ischemia via the ST segment
what is a limitation of the holter monitor
- pts w serious ventricular dysrhytmias may not experience them during the monitored time
what are event monitors
- recorders activated by the pt & can only be used when they are experiencing symptoms
- pt then transmits the rhythm to a central monitoring company via phone
what is a pro to event monitors
- easier method of documenting a dysrhythmia than the 24 hr method, especially if symptoms are not occurring daily
what is exercise treadmill testing used for
- evaluation of cardiac rhythmn in response to exercise
what is important to assess after we know the rhythmn and HR
BP
- some dysrhythmias cause rlly low BP –> if low for long period of time = more & more bradycardia = eventually astolic and MI
what is sinus bradycardia
- conduction pathway is the same as in sinus rhythm
- but SA node fires at less than 60 beats/min
what can cause sinus bradycardia (9)
- sleep
- carotid sinus massage
- hypothermia
- increased intraocular pressure
- increased vagal tone
- hypothyroidism
- increased ICP
- obstructive jaundice
- inferior wall MI
what are signs of sinus bradycardia (8)
- pale & cool skin
- hypotension
- weakness
- agina
- dizziness
- syncope
- confusion & disorientation
- SOB
what is sinus tachycardia
- conduction pathway is same as normal sinus rhythmn
- but SA node firing at faster than 100 beats/min
what can cause sinus tachy (13)
- exercise
- fever
- hypotension
- hypovolemia
- anemia
- hypoxia
- hypoglycemia
- MI
- HF
- hyperthyroidism
- anxiety
- fear
- effect of drugs (epi, norepi, caffeine, atropine)
what are signs of sinus tachy (5)
- dizzy
- dyspnea
- hypertension
- increased MI consumption
- angina
what is atrial fibrillation
- characterized by total disorganization on atrial electrical activity , resulting in loss of effective atrial contractionw
= atria beat irregularly (quiver) = do not beat effectively to push fluid into ventricles
what is the focus of treatment for afib
- rapid assessment on potential hemodynamic instability
- treat underlying cause
what is the most common dysrhytmia
- afib
what are risk factors for afib (13)
- increasing age
- CAD
- rheumatic heart disease
- cardiomyopathy
- HTN heart disease
- HF
- pericarditis
- alcohol
- caffeine use
- electrolyte disturbances
- stress
- cardiac surgery
- thyrotoxicotis
what does an ECG look like during afib (3)
- v high atrial rate
- high or low ventricular rate
- P waves replace by chatoic, fibrillatory waves
what can afib result in (4)
- decreased CO
- thrombi formation
- stroke
- low BP
how does afib result in decreased CO & BP (4)
- ineffective atrial contraction
- loss of atrial kick
- rapid ventricular response
- heart and atria not able to fill and contract to move blood to ventricles like it should
how does afib lead to clot formation
- d/t blood stasis
what is the goal of treatment for afib (5)
- decrease & control ventricular response
- prevent thrombi –> cerebral embolic response (stroke)
- get back into normal sinus rhythm
- treat cause
- treat low BP
what may be used to convert afib back to NSR (3)
- cardioversion
- antidysrhytmia drugs
- long term anticoag treatment
before cardioverting a pt with afib, what must the nurse do? why?
- determine that the pt has had afib for less than 48 h
- cardioversion can cause clots to dislodge = increased risk of stroke
when is cardioversion contraindicated
- if clot is present
what is done to avoid a stroke during afib
- anticoag treatment
describe how afib presents chronically
- chronic on and off
- body goes from NSR to afib, etc.
what can trigger the flip to afib (4)
- body under stress
- illness
- fluid overload
- stressors
what is AV heart block
- partial or complete interuption of impulse transmission from the atria to ventricles
what are the types of AV blokc
- first degree
- second degree (type 1 and 2)
- third degree
what is first degree AV block
- type of AV block in which every impulse is conducted to the ventricles
- but the duration of AV conduction is prolonged
1st degree AV block is associated w (6)
- MI
- CAD
- rheumatic fever
- hyperthyroidism
- vagal stimualtion
- drugsd
what drugs can cause 1st degree AV block (3)
- beta blockers
- calcium channel blockers
- flecainide
what ECG characteristics are seen during 1st degree AV block (5)
- HR normal
- rhythmn regular
- P wave normal
- PR interval prolonged
- QRS normal shape and duration
what is the clinical signif of 1st degree AV block (3)
- not serious
- may be a precursor for higher degree AV blocks
- no symptoms
what us treatment for 1st degree AV block (3)
- no treatment
- modification to causative meds
- continue to monitor
what is 2nd degree AV block , type 1
= mobitz 1 or wenckebach’s heart block
- includes gradual lengthening of PR interval
- occurs d/t prolonged AV conduction time until an atrial impulse is not conducted & a QRS complex is blocked
what can cause 2nd degree AV block, type 1 (3)
- drugs
- CAD
- diseases that slow AV conduction
what drugs can cause 2nd degree AV block, type 1 (2)
- digoxin
- beta blockers
what ECG characteristics are seen with 2nd degree AV block, type 1 (6)
- atrial rate normal
- ventricular rate slower d/t unconducted atrial impulses or blocked QRS complexes
- lengthened PR interval until another QRS is blocked
- irreg. ventricular rhythmn
- P wave normal shape
- QRS normal shape and duration
what is 2nd degree AV block, type 1 usually caused by
- MI or myocardial ischemia
what is the clinical signif of 2nd degree AV block type 1
- may be a warning signal for a more serious SV block
what is the treatment for 2nd degree AV block type 1 if they have symptoms
- meds (atropine) to increase HR
- temp pacemaker
if the pt has no symptoms w 2nd degree AV block type 1, what is the treatment
- closely monitor rhythm
- monitor for hypotension
what is 2nd degree AV block, type 2
- a P wave is not conducted w progressive antedecent PR interval lengthening
= certain number of impulses from the SA node are not conducted to the ventricles = get ratios of 2:1, 3:1 etc.
what usually causes 2nd degree AV block, type 2
- block in one of the bundle branches
what is associated w 2nd degree AV block, type 2 (4)
- rheumatic heart disease
- CAD
- anterior MI
- digitaliz toxicity
what are ECG characteristics of 2nd degree AV block, type 2
- atrial rate normal
- ventricular rate varies on degree of block
- ventricular rhythm irregular
- atrial rhythm regular
- PR interval normal or prolonged
- QRS complex duration increased (d/t bundle brach block)
what is the clinical signif of 2nd degree AV block, type 2
- often progresses to 3rd degree
- associated w poor prognosis
what s/e are seen with 2nd degree AV block, type 2 (3)
- reduced HR = reduced CO
- hypotension
- myocardial ischemia
type 2 AV block is an indication for…
- therapy w a permanent pacemaker
what is treatment for type 2 AV block
- temporary treatment before placement of pacemaker if symptomatic ex. temporary pacemaker
what is type 2 AV block called
- mobitz 2 heart block
what is 3rd degree AV Block
- complete heart block
- no impulses from the atria are conducted to the ventricles
- atria are stimulated and contract independently from the ventricles
- very serious & severe, emergency
what can cause 3rd degree AV block
- heart disease
- CAD
- MI
- myocarditis
- cardiomyopathy
- meds
what meds can cause 3rd degree heart block
- digoxin
- beta blockers
- calcium channel blockers
what ECG characteristics are present in 3rd degree heart block
- P wave normal shpe
- variable PR intervak
- no time relationship between P and QRS complex
what does 3rd degree heart block result on (5)
- reduced CO
- ischemia
- HF
- cardiogenic shock w/in 30 sec
- syncope
what is treatment for 3rd degree heart block if they have symptoms
- temporary pacemaker –> permanent
- meds to increase HR and support BP until pacemaker is initiated
what meds are used to treat 3rd degree heart block (4)
- atropine
- epi
- isoproterenol
- dopamine
what is ventricular fibrillation
- severe derangement of the heart rhythm where the ventricles are “quivering” and have no effective contarction
what can cause v fib (9)
- acute MI
- myocardial ischemia
- CAD
- cardiomyopathy
- accidental electric shock
- hyperkalemia
- hypoxemia
- acidosis
- drug toxicity
what ECG characteristics are present in v fib (4)
- HR not measureable
- rhythm irregular and choatic
- PR and QRS intervals not measureable
= no T wave seen
what signs are seen in a pt w v fib (5)
- pt unresponsive
- pulseless
- apneic state
- no contraction of ventricles = no BP = no CO
- if not rapidly treated, pt will die
what is treatment of v fib (6)
- assess circulation
- assess ABCs
- if no pulse found = advanced cardiac life support
- CPR
- defibrillation
- ACLS meds
what is an example of an ACLS med
- epi
what is asystole
- represents the total absence of ventricular activity
- the pt has died = code blue
- lethal & requires immediate treatment
what can cause asystole (3)
- advanced cardiac disease
- severe cardiac conduction system disturbance
- end stage HF
what ECG characteristics are seen in asystole
- no activity
- on occassion P waves detected
describe pts during asystole (3)
- unresponsive
- pulseless
- apneic
poor prognosis
what is treatment of asystole (5)
- CPR
- advanced cardiac life support (ACLS) such as:
- intubation
- transcutaneous pacing
- IV therapy w epi and atropine
is asystole shockable
- no
what is sudden cardiac death (SCD)
- unexpected death resulting various causes, including cardiac arrest
- refers to death from a cardiac cause
what are most SCDS caused by (3)
- ventricular dysarhythmias (specifically v tachy or v fib)
- also by primary left ventricular outflow obstruction
- extreme slowing of the heart
describe the onset of SCD
- often not sudden
- most have awareness of cardiac symptoms in the hour before
what are acute symptoms of SCD (cardiac arrest)
- angina
- palpitation
- SOB
what occurs in SCD (5)
- cardiac fnxn disrupted abruptly = immediate loss of CO & cerebral blood flow = decreased BP = stopped HR = pass out
describe the hx of a patient with SCD
- may or may not have history of CAD
death from SCD usually occurs…
- 1 hr from onset of acute symptoms
people who experience SCD d/t CAD are categorized as..
- those who did not have an acute MI
- those who did have an acute MI
what category of SCD accounts for most cases of SCD? why?
- those who did not have an acute MI
- bc get no warning signs or symptoms
what are risk factors for SCD (7)
- male sex
- FHx of premature atherosclerosis
- tobacco use
- DM
- hypercholesterolemia
- HTN
- cardiomyopathy
what interventions have helped increased survival rate r/t SCD
- CPR
- defib with an AED
pts who survive SCD require (5 ish?)
- diagnostic workup to determine if they had a MI
= ECG, cardiac markers, cardiac catheterization (to determine extent of CAD) - PCI
- CABG
- and then treatment is planned accordingly
most pts with SCD have…
- a lethal ventricular dysrhytmia that has a high incidence of recurrence
= useful to know when they are most likely to have a recurrence and what drug therapy is most effective
what is done to assess dysrhytmias in a pt who survived SCD
- 24-hr holter monitoring
- event recorders
- exercise stress testing
- signal-averaged ECG
- electrophysiological study performed w fluroscopy
- pacing electrodes to attempt to produce dysrhytmias
what is the most common approach to prevent recurrence of SCD
- use of an implantable cardioverter-defibrillator (ICD)
what is an ICD
- small battery-powered device placed in your chest to detect and stop abnormal heartbeats (arrhythmias)
- continuously monitors your heartbeat and delivers electric shocks, when needed, to restore a normal heart rhythm
what else is used to prevent recurrence of SCD
- meds (ex. amiodrone) to decrease ventricular dysrhytmias
when caring for pts who have survive SCD, what is included in nursing care (5)
- alert to pts psychosocial adaptation to this sudden “brush w death”
- help manage anxiety and depression (d/t time bomb mentality)
- possible driving restriction
- possible change in occupation
- emotional support
