Clin Med - Arrhythmias Flashcards
What are the types of AV blocks?
- first degree
- second degre: mobitz typ I (Wenckenbach) and mobtiz type II
- third degree
general presentation on EKG of first degree AV block
-PR interval > .21 sec with ALL atrial pulses CONDUCTED
general presentation on EKG of second degree AV block
-INTERMITTENT blocked beats
general presentation on EKG of third degree AV block
- COMPLETE heart block
- no atrial impulses are conducted to the ventricles
medications in the etiology of first and second degree heart block
- digitalis
- Ca++ channel blockers
- beta blockers
chronic or transient etiologies of first and second degree heart block
- ischemia
- inflammatory dzs (lymes)
- fibrosis
- calcifications
- infarction
in a second degree, mobitz type I (Wenchenbach), what is the pattern of the PR interval? and the cause?
- PR interval progressively lengthens w/ RR interval shortening before a dropped beat
- almost always d/t AV node conduction abnormality
What are the characteristics of a second degree mobitz type II AV block?
- no lengthening of AV conduction
- intermittent non-conducted atrial beats
- usually d/t dz involving bundle of His
- may progress to 3rd degree block
which AV block is usually “nodal so narrow” ?
-Mobitz I
narrow in terms of QRS
Which AV block is usually “infranodal so wide” ?
-Mobitz II
A third degree heart block is usually d/t what?
a lesion distal to the bundle of His
3rd degree heart block may be associated with what other arrhythmia?
bilateral BBB
characteristics of a third degree heart block
- QRS wide and ventricular beats usual <45 BPM
- atrial conduction through atrial node is completely blocked
- may be asymptomatic
- may feel fatigues, SOB, have syncope
EKG notes from a 3rd degree block
- no dropped beats
- all p waves come at the same interval
- atria and ventricles are working just not working together
- p wave may show up in the QRS
How is an AV block diagnosed?
- incidental finding or
- symptomatic patient gets EKG
PE of pt w/ AV block
- bradycardia
- may be asymptomatic
When does AV block only need monitoring?
-asymptomatic pts w/ good perfusion
What is the treatment for AV block when they do not qualify for monitoring only?
permanent pacing
When does AV block require permanent pacing as treatment?
- symptomatic bradyarrhythmias
- asymptomatic mobitz type II
- complete heart block
BBB definition
- a complete or partial interruption of the electrical pathways of the bundle of his
- can be right, left, bifasciular or trifasicular
bifasicular
- when 2 pathways are blocked
- right bundle, left bundle, posterior fascicle, left anterior fascicle
trifasicular
- RBBB with alternating left hemi-block
- alternating RBBB and LBBB
- bifasicular block w/ prolonged infranodal conduction
T or F; BBBs can occur in normal hearts.
True
What dz processes can cause BBBs
- ischemic heart dz
- inflammatory dz
- infiltrative dz
- cardiomyopathy
- postcardiotomy
what dz processes are specific to RBBBs
- pulmonary embolism
- chronic lung dz
symptoms of BBB
- most have none
- syncope
- the symptoms of the underlying cause
diagnosing BBB
- incidental finding
- EKG if symptomatic
tx of BBB
- tx underlying disorder
- may need pace maker if syncope is occuring
- most need none
paroxysmal supraventricular tachycardia (PSVT) definiton
-regular, fast (160-200) HR that originated in heart tissue other than the ventricles
etiology of PSVT
- accessory pathways of electrical conduction b/w the atria and the ventricles
- AV node is bypassed
sx of PSVT
- some can have very mild sx
- palpitations
- dizziness
- syncope
- light headed
- chest pain
- SOB
- weakness/fatigue
PE findings in PSVT
-tachy and regular rhythm
What will diagnose PSVT when using and EKG or holter monitor?
- rapid regular rhythm
- QRS could be narrow or wide
- may have delta wave present (preexcitation)
vagal stimulation treatments
- plunging face into ice water
- rubbing neck just below jaw line
- bare down
- cough
when do you use medical intervention as opposed to vagal stimulation?
- if vagal stim. doesn’t work
- if episode lasts more than 20 min
- if symptoms are severe
What defines a PSVT patient as unstable?
- hypotension
- altered mental status
- signs of shock
- chest pain
- heart failure
treatment of unstable PSVT patient
- try vagal maneuvers while prepping for:
- synchronized cardioversion
- consider adenosine 6mg
treatment of stable PSVT patient
- vagal maneuvers frist
- consider adenosine if vagal stim. doesn’t work
- beta blocker or Ca++ channel blocker
Wolf-parkinson white syndrome (WPW)
- supraventricular tachy arrhythmia
- preexcitation pathway
What is the defining feature of WPW on EKG?
-delta wave
What is the possible progression of WPW?
- up to 30% will develop a. fib or flutter
- can degenerate into v. fib
- needs electrophys and often ablation
When does a patient with PSVT need to see a specialist?
- WPW pattern on EKG
- pts w/ recurrent sx despite tx
- pts w/ pre-excitation and hx of a fib/flutter
When do you admit a PSVT patient?
- syncope
- hx of syncope and pre-excitation on EKG
PVC
- ventricular extrasystoles
- isolated beats that originate from ventricular tissue occurring before a normal heartbeat
sx of PVC
- commonly none
- may be aware of strong/skipped beat
if PVCs are frequent, what could the progress to?
- v. tach
- v. fib
causes/risk factors for PVCs
- age
- alcohol (boo)
- caffeine (boo)
- cold meds
- CAD
- heart failure
- stress (boo)
- valve disorders
- electrolyte disorders
- hyperthyroidism
diagnosis of PVCs
- w/ EKG or holter
- may be individual beats
- bigeminy or trigeminy
increased frequency of PVCs during exercise is associated w/ what?
increased risk of cardiovascular mortality
what do you rule out before treating PVCs
- electrolyte disorder
- thyroid disorder
in a generally healthy pt w/ no other problems, what is the treatment for PVCs?
- none required
- avoid caffeine, stimulants and reduce stress
in pts w/ structural herat dz or bothersome sx, what is the treatment for PVCs?
- beta blockers
- weight risks w/ benefits for tx
In pts with frequent PVCs refractory to other tx, what is the option?
catheter ablation
sick sinus syndrome
- sinus arrest
- sinoatrial exit block
- persistant sinus brady w/ no specific cause
- can alternate brady-tachy
- brady d/t disordered SA node or impaired conduction from SA to atrium
what is the characteristic feature of sick sinus syndrome?
the heart does not respond to normal stimuli to increase the rate such as exercise
misc. facts about sick sinus syndrome
- usually asymtomatic
- usually elderly
- may have intermittent SVT mixed w/ the brady-arrhythmia
- often have concomittant a. fib
- may be caused by meds
diagnosing sick sinus syndrome
- sometime hard
- PE
- ECG w/ carotid sinus pressure (not done in office)
- ambulatory monitor or electrophys studies
what meds can cause sick sinus syndrome?
- beta blockers
- Ca++ channel blockers
- digoxin
- sympatholytic agents (clonidine, gaufcaine, alpha methyldopa)
- antiarrhythmics
what are causes of sick sinus syndrome not related to meds?
- sarcoidosis
- amyloidosis
- Chagas dz (parasite from bug poop)
- various cardiomyopathies
what is NOT a common cause of sick sinus syndrome?
coronary dz
symptoms of sick sinus syndrome
- mostly asymptomatic
- syncope
- dizziness
- confusion
- palpitations
- fatigue
- heart failure
- angina
tx of sick sinus syndrome if pt is asymtomatic
-non as long as perfusion is good
whats the first step in the tx of sick sinus syndrome?
remove any offending meds to see if it resolves
what’s the tx for sick sinus syndrome in symptomatic pts?
- permanent pacing
- dual is preferred
- pace first, then tx for the tachyarrhythmias
torsades de pointes
form of ventricular tachy in which QRS morphology inverts around the baseline of the EKG
etiology of torsades
- hypokalemia
- hypomagnesemia
- drugs that prolong QT interval
sx of torsades
(same as v. tach)
- fainting
- angina
- lightheadedness
- dizziness
- palpitations
- SOB
diagnosing torsades
- EKG
- lab studies for electrolytes
- echo
- electrophys
what is the treatment of choice for torsades?
-IV mag sulfate
alternative treatment for torsades?
- IV beta blockers
- cardiac pacing
ventricular tachycardia
- 3 or more consecutive ventricular premature beats
- >100 bpm
sustained vs. non sustained criteria for v. tach
- NON-sustained: <30s
- sustained: >30s
sx of v. tach
- fainting
- angina
- lightheadedness
- dizziness
- palpitations
- SOB
causes/risk factors of v. tach
- structural abnormality in heart
- prior MI
- CAD
- heart failure
- previous heart surgery
- myocarditis
- heart valve dz
what are other causes of v. tach
- antiarrhythmic meds
- changes in blood chemistry or pH
- lack of O2
PE in v. tach
- rapid HR
- low BP
- LOC
- absent pulse
diagnosis of v tach
- EKG
- echo
- CXR
- angio if echo is inconclusive
- electrophys
- cardiac MRI
what is true in all cases of sustained v tach?
- all should be admitted
- emergent
in sustained v tach, if pt has symptoms (hypotension, shock, chest pain, etc.), what is the treatment?
- CPR, ACLS protocol
- cardioversion
in cardioversion of sustained v. tach, what are the guidelines?
- wide/regular: 100J synchronized
- wide/irregular: defib
in sustained v. tach that is urgent but w/o symptoms, what is the treatment?
- IV access
- EKG
- lab studies
- consider adenosine
- consider antiarrhythmic infusion
treatment of NON-sustained v. tach
- lab studies and CXR
- if no heart dz, may not need tx
- w/ heart dz: beta blockers
- amiodarone is a consideration
if a pt. w/ non-sustained v. tach has sustained v. tach during electrophys studies, what is the treatment?
implantable defibrillator
v. fib
- ventricles of the heart quiver or fibrilate which stops adequate blood flow from heart
- fatal unless immediately corrected
etiology of v. fib
- v. tach
- acute ischemia or infarct
- complete heart block
- sinus node arrest
- CAD
- acidosis
other risk factors for v. fib
- drowning/hypothermia
- drugs (legal and illegal)
- electrical shock
- very low BP
- hypo/hyperkalemia
- previous MI
- congenital heart dz
- cardiomyopathy
- pneumothorax
- thrombosis
- tamponade
- hypovolemia
S/S of v. fib
- sudden loss of responsiveness
- not breathing or only gasping
what are early signs of v. fib?
- chest pain
- rapid heartbeat
- dizziness
- nausea
- SOB
- LOC
Tx of v. fib?
- CPR ACLS
- O2
- attach monitor
- check rhythm
- shock
- start IV
- continue CPR
- advanced airway
- drug therapy (epi and amiodarone)
- tx reversible causes
diagnosis of v. fib
- always emergent situation
- after ACLS/CPR to resume life sustaining rhythm, you can ID the cause of it
