Arrythmias, Conduction Blocks and EKGs Flashcards
Define parameters associated w/ bradycardia and tachycardia
brady <60
tachy >100bpm
define Symptomatic Bradycardia and compare it to sleep bradycardia
usually below 40 AND does not increase with physiological demand
•During sleep: common HR to drop below 60, even below 50 and sometimes below 40 without consequence
•most common ECG finding with PE is ____ ____
sinus tachycardia
si/ sx of sinus tachycardia
include sx in pts w CAD
Asymptomatic
Heart palpitations
Shortness of breath (especially with exertion) – feel they cannot catch their breath
CAD:
- Heart palpitations
- Shortness of breath – anginal sx
- Chest discomfort à sinus tach causes cardiac ischemia due to supply/demand mismatch
- Lightheadedness
- Fatigue
how do we tx sinus tachycardia
tx underlying cause
Si/Sx of SVT
••Sudden onset racing heart palpitations ** that fades suddenly
comes on suddenly and fades suddenly
contrast pathophysiologies of AVRT vs AVNRT
AVNRT Abnormal re-entrant loop around the AV node
AVRT -
Accessory pathway b/w atria and ventricle –> signal goes around and around causing tachycardia
defne pathophysiology for junctional rhythm
AV node is pacemaker -> depolarizing quickly and causing rapid HR
Junctional pacemakers usually 40-60bpm (ventricular rate)
•Differentiate based on junctional rate
recall treatment for stable SVT
first and second line
unstable SVT?
first - vagal maneuvers
second adenosine
unstable
vagal maneuvers
if unsuccessful - DC cardioversion
list meds that prolong QTc interval
Antiarrhythmic agents
- Amiodarone
- Flecainide
- Sotalol
- Antipsychotics
- Chlorpromazine
- Haloperidol
- Olanzapine
- Quetiapine
- Risperidone
- Antibiotics
- Macrolides – azithromycin
- Quinolones – levo, cipro
- Antidepressants
- Citalopram
- TCAs
length of QTc that puts pts at risk for ventricular arrythmias
QTc greater than 500 milliseconds (ms) puts patient at risk for ventricular arrythmias (Torsade de Pointe)
Si/Sx of Vtach
- Conscious w/ pulse – will show symptoms
- Unconscious with pulse
- Unconscious w/o pulse
- Heart palpitations
- Lightheadedness
- Chest pain
- Shortness of breath
- Diaphoresis (drenching sweat)
- Near syncope
- Syncope
- Sustained LOC
- Pulseless (death)
tx for vtach
Pulse present:
stable - amiodarone 150 mg IV followed by continuous infusion
unstable - cardioversion
long term implantable device
pulselessness:
CPR
- Defibrillation – as soon as it is available place on chest
- Epinephrine
- ICD
tx for torsade de pointe
first and second line
Stable
- First line: give Mg before you check levels
- Temporary transverse overdrive pacing if no response to Mg –> external pacer
Second line – if persistent or Unstable –> prompt defibrillation
causes of Vfib
•Myocardial ischemia / MI
- HF
- Hypoxemia or hypercapnia
- Hypotension / shock
- Electrolyte imbalances
- Stimulants (drugs, caffeine)
- Often preceded by Vtach
tx vfib
CPR
Defibrillation – IMMEDIATE (no cardiac output)
If pulse regained: coronary arteriography (cardiac catheterization) to tx CAD
Implantable cardioverter-defibrillator for long term management
describe conduction pathway of WPW
Accessory pathway (delta wave) creates preexcitation à electoral impulses arrive to ventricle early and bypass AV node
_Orthodromic AVR_T (narrow complex) – more common
•Impulse transmits anterograde down AV to ventricles and retrograde to atria up through accessory pathway
Antidromic AVRT (wide complex) - Opposite of above
complications of WPW in the setting of rapid afib
• can lead to dangerous ventricular arrythmias
standard tx for WPW
Nonpharmacologic – catheter ablation of accessory pathway
Pharmacologic – to slow ventricular heart rates / prevent arrythmias
differentiate b/w sustained vs nonsustained Vtach
Sustained ventricular tachycardia - 3 or more consecutive beats of ventricular origin
•Lead to vfib à death
Non-sustained ventricular tachycardia – less then 3 ventricular beats , <30s
•Asymptomatic
what is Torsades triggerd by?
- Hypokalemia – check levels before administration
- Hypomagnesemia – ok for emergent administration
- Drugs that prolong QTc
what type of arrythmia is associated w/ syncope and is a frequent complication of MI and dilated CM
SVT
what type of arrythmia is associated w/ severe CAD caused by acute MI
VFib
name some narrow complex rhythms
sinus tachycardia
SVT
AVNRT
AVRT
WPW - orthodromic AVRT
name some wide complex rhythms
sustained ventricular tachycardia
Torsade de pointe
Vfib
define the classes of Afib
Paroxysmal
persistent
long-standing
permanent
“Lone-AF”
refractory
- Paroxysmal (PAF) - intermittent
- Persistent - fails to self-terminate within 7 days & requires intervention in order to convert
- Long-standing - >12 months
- Permanent - >12 months & no longer pursue rhythm control
- “Lone AF” – without structural heart disease, lowest risk of complications.
- term not used much anymore
- Example is if patient underwent heart surgery and developed afib once after as heart was healing
- Refractory – not responding well to therapy/ keeps returning.
risk factors associated w/ Afib and Aflutter
- >65 y/o
- Men>women
- Whites most common
- Hypertension
- Elevated BMI
- Prolonged PR interval
- Valvular disease
- CHF
Triggers for Afib
- Sleep deprivation
- Physical illness
- Post-surgery
- Stress
- Hyperthyroidism
- Physical exercise
- Stimulant meds (Sudafed)
- Alcohol
- Caffeine
- Dehydration
workup in pt w/ newly diagnosed Afib
Hx and PE
- ECG – narrow QRS, irregular, no p wave
- Echo – look at mitral valve – if mitral valve disease put on anti-coagulation
- Stress test
- Labs: CBC, BMP, kidney function tests , TSH (new afib ALWAYS get both)
- Exercise stress test – assess for ischemic heart disease
- Heart monitors
FIRST Echo TTE –less invasive
•valvular heart disease (MS/ rheumatic heart disease )
SECOND Echo TEE – more invasive
•More sensitive for dx atrial thrombus à prior to cardioversion
describe a TEE echo vs TTE echo
FIRST Echo TTE –less invasive
•valvular heart disease (MS/ rheumatic heart disease )
SECOND Echo TEE – more invasive
•More sensitive for dx atrial thrombus à prior to cardioversion
goals of therapy w/ afib
- Rhythm control
- Reduce risk of stroke
- Prevent tachycardia mediated cardiomyopathy and ischemia (rate control)
- Alleviate symptoms
outline pharmacologic tx for Afib
first line - BBs or CCBs
metropolol and diltiazem (preferred in ED)
Adjuncts after maximizing BB or CCB
Digoxin - monior for dig tox
amiodarone (antiarrythmic) added in refractory Afib w/ RVR - lots of side effects
Most common side effect associated w/ amiodarone
- Abnormal LFTs
- Pulmonary toxicity – several months or years after initiation
- Most common is chronic interstitial pneumonitis
what are symptoms of digoxi toxicity?
what is digoxin effect?
- Symptoms: fatigue, dizziness, nausea (nonspecific)
- ECG changes – heart blocks
- Digoxin effect – normal to see on ECG of patients taking digoxin – Salvador dali mustache (nontoxic levels)
tx for aflutter w/ RVR
- Control ventricular rate - More difficult to control then afib
- FIRST LINE – BB or CCB
- Digoxin can be added, No amiodarone
- Convert to NSR / maintain NSR
•Ablation of IVC-TA area to break circuit
- Prevention of systemic embolization (stroke)
•Assess stroke risk - add anticoag if necessary
where is ablation performed
for what condition?
- Type 1 aflutter
- Ablation of macro reentrant pathway in right atrium involving obligatory pathway between inferior vena cava and tricuspid annulus (IVC-TA area)
outline tx for tachycardia in afib w/ RVR in acute and long term settings
ACUTE - FIRST line - BB or CCB in ED setting usually diltiazem drip
chronic - discharge on PO BB / CCB
- Oral metoprolol BID – long-acting Toprol dosed once daily
- Nadolol PO (liver failure pts / portal HTN)
- Carvedilol (HF pts)
consider Adjuncts:
- Digoxin – added if BB insufficient or intolerant
- Amiodarone – slow rate in refractory Afib
Cardioversion - if necessary
indications for urgent cardioversion
- Active ischemia
- Unstable hemodynamics
- Evidence of organ hypoperfusion
- Severe manifestations of heart failure (pulmonary edema)
- The presence of WPW
indications for nonurgent cardioversion
- New onset or newly recognized afib –> r/out clots!
- Pts with persistent afib who are limited by their symptoms
Reasons NOT TO cardiovert
- Known afib that is minimal symptomatic
- Multiple comorbidities
- Unlikely to maintain NSR
- Age - Benefits of cardioversion decrease after 80 years old
- Paroxysmal afib
describe measures taken before cardioversion is preformed
•Prior to cardioversion:
control ventricular rate & provide intravenous heparin
when is a full anticoagulation or assessment for atrial thrombus prior to cardioversion indicated
Afib >48 hrs
How do we assess for stroke
CHADs2
CHADs VASc
what are the stroke score models called that we use to assess for stroke risk prior to cardioversion
CHADS2 Score –assess annual risk of stroke
CHA2DS2-VASc –Considers age, use if score 1 or 2 on CHADS2
define CHADS2 Score and what scores are risks for stroke
- 0 – no anticoagulation therapy, low risk
- 1 or 2 – move onto CHA2DS2-VASc scoring system (i_ntermediate risk_)
- 2 – get anticoagulation usually
- >3 – high risk, provide anticoagulation
describe how the CHA2DS2-VASc model differs from CHADS2 model and how we use it to assess stroke risk.
Considers age, use if score 1 or 2 on CHADS2
IF CHADS2 score is 1 or 2 – move onto CHA2DS2-VASc scoring system
- 0 – stroke risk 0%
- 9- stroke risk 15%
- >2 – long term anticoagulation
if patients are higher risk for stroke what should we always do before performing a cardioversion
anticoag for 3 weeks prior
warfarin - usually (monitor INR)
- Dabigatran (Pradaxa)
- Rivaroxaban (Xarelto)
- Apixaban (Eliquis)
•Most common sustained arrythmia and is associated with mitral valve disease
Afib
describe pathogenesis of afib vs aflutter
afib
- Disruption of electrical conduction system usually by infiltration of inflammation of the atria
- Ectopic foci are most often located at the ostial portion of the pulmonary veins
Disorganized, rapid and irregular loss of atrial activation à loss of atrial contractility
•Results in irregular ventricular response
aflutter
- Large macro reentrant excitation in circuit of the right atrium
- Large macro reentrant pathway in right atrium involving obligatory pathways between inferior vena cava and tricuspid annulus
•Commonly occurs after initiation of antiarrhythmic drugs for atrial fibrillation
aflutter
is amiodarone used in aflutter
no - only 20-30% effective at maintaining NSR
•Atrial enlargement is most likely cause – rogue pacemakers who steal show from AV node
is describing?
Afib
how does new onset Afib present
- Heart palpitations
- Fatigue
- Lightheadedness
- Dyspnea
- Angina
- Incidental
afib w/ RVR is differeniated when what symptom is noted?
heart palpitations probably noted
valular heart disease is associated with?
how do we ALWAYS manage these pts?
Afib
life-long anticoags - increased risk for thromboemolism
Most common etiologies of first degree heart block
- Progressive Cardiac Conduction Diseases (50% of cases) –> fibrosis and sclerosis
- Ischemic heart disease (40% of cases) –> after MI resulting in death of cells that cannot conduct properly
tx of first degree AVB
If PR interval <300msec w/ narrow QRS - no intervention
If assoc wide QRS - delay may be below AV node, between His bundle and ventricles –> uncertain progression
•refer to EP for study and consideration for pacemaker
Treat underlying cause
avoid AV nodal blocking meds –> CCBs or BBs
what conduction blocks are indications for pacemakers
first degree AVB - if wide QRS complex
Second degree type I - if syncope/ other sx in setting of wide complex
second degree type II - ALL
third degree AVB - ALL
tx for second degree AVB type II
Tx underlying cause
Avoid AV nodal blocking meds
ALL will need pacemakers
tx for third degree AVB
Temporary pacer – IMMEDIATELY
•Refer to EP
Tx underlying cause
Avoid AV nodal blocking meds
what conuction blocks are likely to lead to complete heart block / worsening prognosis
second degree type II
heart block that is:
Asymptomatic
Normal (athletes and sick hearts)
Rarely progress to complete heart block
Second Degree –
Type I Wenckebache
sx in second degree AVB type II if slow rate or frequent dropped beats
If slow rate or frequent dropped beats
- Fatigue
- Lightheadedness
- Syncope
tx for second degree AVB type I Wenckebache
Tx underlying cause
Avoid AV nodal blocking meds
Monitor EKG for progression to Type II
Asymptomatic – no tx
Syncope or other sx – refer to EP for pacemaker
- Marked prolongation of conduction b/w his bundle and ventricles
- Wide complex in setting of symptoms
si/sx of third degree AVB
Chest pain – in setting of MI
Lightheadedness
Fatigue, weakness, exertional dyspnea, bradycardia
•Due to DEC CO bc of dropped beats
Ventricular tachycardia to Vfib then death
•Vtach due to physiologic demand
contrast PR interval in second degree heart block type I vs II
type I wecke - Progressively lengthening PR interval until dropped beat occurs
type II - PR intervals equal in length until dropped beat occurs
define a STEMI equivalent
- New LBBB in setting of chest pain –> cath lab
- Highly likely it is a MI
which arrythmia is associated:
with INC risk of hospitalization for HF in pts w/ stable coronary heart disease
first degree AVB
arrythmis associated w/ increased mortality in setting of CAD
LBBB
if elderly present w/ LBBB find CAD!!
management of LBBB
Young, asymptomatic w/ no CAD -> no tx
STEMI equivalent to cath lab
Tx underlying conditions
Manage risk reduction in CAD
- Well controlled BP
- Well controlled diabetes
describe EKG findings
sinus tachy
Narrow QRS complex
- Fast and regular
- P-waves are seen
identify EKG arrythmia
next steps?
Sinus Tachycardia. Treat underlying cause (if you even need to)
identify arrythmia and next steps
Atrial fibrillation.
Consider cardioversion if onset <48hrs.
Get an echo if it’s a new diagnosis.
Calculate CHADS 2 score for consideration of anticoagulation for stroke prevention.
Afib with RVR
Rapid afib puts a patient at risk for pulmonary edema due to poor forward contractile forces and fluid gets backed up in lungs.
It also puts patients at risk for demand ischemia in CAD as the rate is too fast to adequately perfuse the myocardium itself
It is common to see rate related ischemic changes such as ST depressions in rapid afib.
Treat: Rate control with AV nodal blocking CCB (diltiazem) or BBs (metoprolol).
Slow Aflutter
Note the classic _saw toothed pattern of the p wave_s (aka flutter waves).
This patient has bradycardia so you want to know if he is symptomatic and if he is on medications that lower heart rate, perhaps you need to back off those a bit.
Aflutter, like a fib, has a propensity to go fast.
If rapid, tx with nodal blocking agents and if meds are not effective consider ablation or cardioversion.
(SVT).
It is a regular rhythm so it’s not afib.
You can not see p waves so it is not sinus tach.
SVT usually originates either from the AV node itself (a junctional rhythm) or from a reentrant circuit around the AV node (AVNRT) (most common).
SVT can happen in normal hearts and sick hearts.
It is usually sudden onset and has sudden cessation.
To treat: perform vagal maneuvers, carotid massage (listen for carotid bruits first) and if those don’t work, then give adenosine first dose is 6mg, then 6mg, then 12mg. (In real life, my advice is don’t do carotid massage in patients over 50, the risk of causing a stroke from dislodging carotid plague is not worth it)
1st degree AV block (1˚ AVB).
Can be found in normal hearts.
Don’t worry about the patient.
Ventricular fibrillation. T
his patient has no cardiac output because the ventricles are not adequately contracting.
He will be unconscious and pulseless.
Do ACLS protocol:
- Call for help (call a code).
- Start CPR,
- defibrillate as soon as the defibrillator is available.
- epi (epinephrine)
3rd degree heart block.
The first clue is the variable PR intervals which are not following the Wenckebach pattern.
Note how the p waves march out at a certain rate (consistent intervals between p waves) and the QRS complexes march out at a certain rate, but they have nothing to do with each other (AV dissociation).
They are each, “marching to a different drummer.”
Treat: pacemaker
Inferior ST elevation myocardia infarction (STEMI).
- Active cath lab (door to balloon time <90min.)
- Provide Aspirin.
- Quick physical exam
- Quick history, ask about bleeding disorders.
- Heparin gtt, NTG, morphine if needed.
(Within 24 hours patient also needs beta-blocker and high dose Lipitor). Of course you might use the BB early for blood pressure, or other meds as well.
Torsade de Pointe (a type of ventricular tachycardia). It is caused by QTc prolongation. It is less likely to degrade into V-fib although it can. Tx with Magnesium 2gm IVP. Review the patient’s med list to determine what needs to be discontinued (which meds cause QTc prolongations; ie antipsychotics and antibiotics – namely fluoroquinolones (Levofloxacin) and macrolides (Azithromycin).
Second degree AV block Type I (Wenckebach or Mobitz Type I).
No tx necessary unless symptomatic from bradycardia such as fatigue or syncope then treat with pacer.
This can be seen in normal hearts but it can also degrade into Mobitz Type II.
Normal sinus rhythm develops into ventricular tachycardia.
Call a code whether the patient is conscious or not.
ACLS protocol:
If conscious and otherwise stable, and HR <150 give Amiodarone (antiarrhythmic) otherwise proceed to synchronous cardioversion.
If conscious and unstable; synchronous cardioversion.
If unconscious and pulseless, CPR and defibrillate
Second degree AV block Mobitz Type II –
Note the PR intervals are consistent duration throughout but dropped beats occur.
This is likely to degrade into third degree heart block.
Treat: pacemaker
Right bundle branch block (RBBB).
Note the r-Rˡ in V1 and the wide S waves in V5.
no treatment. Can be found in normal hearts.
Left bundle branch block. (LBBB).
If new LBBB is discovered in a pt presenting with CP, assume ACS.
LBBB is often associated with CAD so get echo, stress test even if not symptomatic
Tachy-brady syndrome. (Sick sinus syndrome with tachy/brady)
(SSS)- often you’ll see actual bradycardia, not just long pauses, but pauses are part of the deal.
Treat with Pacemaker
Sinus bradycardia –
Do you need to treat? Depends if patient is symptomatic.
If you need to treat, atropine immediately and referral to EP for pacemaker.
if new diagnosis Afib what diagnostic test is important to order
echo
Afib puts you at risk for what conditions?
pulmonary edema due to poor forward contractile forces and fluid gets backed up in lungs.
demand ischemia in CAD as the rate is too fast to adequately perfuse the myocardium itself
torsades is caused by
QTc prolongation.
It is less likely to degrade into V-fib although it can.
can Second degree AV block Type I degrade into type II?
yes
tx vtach in:
concious stable pt w/ HR <150
concious unstable
unconcious and pulseless
If conscious and otherwise stable, and HR <150 give Amiodarone .
If conscious and unstable; synchronous cardioversion.
If unconscious and pulseless, CPR and defibrillate
tx for RBBB
none
can be found in normal hearts
how do we work up LBBB?
LBBB is often associated with CAD so get echo
stress test even if not symptomatic.
treatment of bradycardia
pacemaker if symptomatic
WPW - “delta wave”
- A delta wave is slurring of the upstroke of the QRS complex.
- This occurs because the action potential from the SA node is able to conduct to the ventricles very quickly through the accessory pathway
- thus the QRS occurs immediately after the P wave, making the delta wave.
tx of persistent bradycardia
atropine
SVT is most commonly due to:
AVNRT
what does ablation target in
AVNRT
AVRT
junctional
- AVNRT – cause scarring and prevent circuit from going
- AVRT – ablate accessory pathway
- NO junctional
LBBB
V1 - t wave goes up
V6- notches appearance
RBBB
look at V1 and V6
V1 - T goes down
V6 - t wave goes up
