Conduction system disorders Flashcards
symptoms of conduction system disorders
Palpitations: **
- “Extra beat”, “Fluttering”, “Heart beating out of chest”
SOB **
Chest pain **
Diaphoresis - excess sweating
-Dizziness(room spinning- rule out vertigo)/lightheadedness(sit to stand)
Syncope - fainting**
-Cough
-Fatigue
-Weakness
Arrhythmias become significant when disrupts cardiac output
Cryptogenic stroke and ILR
- after stroke of unknown cause -> push for ILR to check for AFIB**
- one stroke significantly increases risk for second stroke
-Crystal AF study: 88% of pts who had afib would have been missed if they were only monitored for 30 days instead of loop
-MRI safe
-3 year monitor
Takes spontaneous recording of:
-Tachycardia
-Bradycardia
-Pauses
-Irregular rhythms
Triggered symptom events recorded
dx of conduction system
1) 12 lead Electrocardiogram (EKG)
2) Holter monitor- 24hrs – 30 days
3) Implantable Loop Recorder (ILR)
- Useful for cryptogenic CVA: check for afib
Palpitations sx/description
-“Extra beat”
-“Fluttering”
-“Heart beating out of chest”
paroxysmal supraventricular tachycardia definition
General term:
- rate 150-250 bpm/min
- NARROW QRS -> normal ventricular depolarization
- rapid heartbeat originating from atria
paroxysmal supraventricular tachycardia types
MC: AV node re-entry**
- P-wave hidden in T-wave
- narrow QRS
- short circuit around the AV node
Other types of PSVT:
-Atrial Tachycardia
-Multifocal Atrial Tachycardia
-Junctional Tachycardia- rapid firing from AV
causes of PSVT
-Excessive caffeine (stop at 2 8oz cups)
-Post myocardial infarction (MI) - ischemic ds
-Structural heart disease
-Chronic lung disease
-Amphetamines
-Myocarditis/pericarditis
-Pulmonary embolism- right heart typically affected
-Idiopathic
PSVT = Please Eat SCAMPI
-pulmonary embolism
-excess alc or caffeine
-structual heart ds
-chronic lung ds
-amphetamines
-myocarditis
-post MI
-idiopathic
SVT acute phase tx for hemodynamically unstable pt
Unstable = synchronized CARDIOVERSION to reset heart
SVT prevention and definitive tx
Prevention:
-Beta-blockers: atenolol, metoprolol, carvedilol
-Calcium cannel blockers: diltiazem, verapamil
Definitive treatment for SVT: radiofrequency ablation **
SVT acute phase tx for hemodynamically stable pt
*Carotid massage NOT RECOMMENDED in elderly -> CVA risk
DEFINITIVE TX: RADIOFREQUENCY ABLATION
first determine if stable vs unstable -> if stable:
1st line: Vagal maneuvers
-Bearing down (valsalva)
- cough
- holding breath
- moves that increase intrathoracic pressure -> stimulate vagus nerve -> slow HR
Pharmacological interventions:
Narrow QRS complex:
- Adenosine: 6mg IV then 12 mg IV push
- causes AV node arrest for 6s
- adenosine temporarily blocks conduction through AV node -> interrupts circuit
Wide QRS complex:
- Amiodarone (prof doesnt recommend)
-note: if you gave adenosine with afib it wouldnt do anything -> not coming from AV node
Amiodarone: description, half life and side effects
Class 3 antiarrhythmic drug - blocks K+ channels; but also Beta, Ca, Na+
Half life: 58 hours
Common side effects:
-Nausea
-Fatigue
-Tremors
Adenosine MOA and half life
MOA:
- causes vasodilation
- Transient heart block at AV node in hopes SA node resets on its own
- Half life <10 seconds
SVT medication for NARROW complex hemodynamically stable
Adenosine ADRs and Contraindications
Most common side effects:
-METALLIC taste*
-“IMPENDING DOOM”*
-Chest pain
-SOB
-Facial flushing
-Lightheadedness
Contraindications:
-Asthma
-Long QT syndrome
-2nd/3rd degree heart blocks
Amiodarone: ADR and contraindications
ADR:
-Hepatotoxicity
-Pulmonary fibrosis
-Optic neuritis
-Thyroid dysfunction- MC
-blue skin discoloration in the sun
Contraindications:
-2nd/3rd degree heart block
-Prolonged QT
-Pregnancy
-Sinus node dysfunction
-“<65 yo, ablation not this, this is a very toxic drug; not good for pts over 65 yrs; dr hates this drug”
atrial fibrillation definition + common cause of afib
Definition:
- rate 350 – 450 bpm
-Multiple foci in the atria rapidly firing - Irregularly irregular rhythm
-NO P-wave present
-Irregular QRS intervals
Common cause:
-“Holiday heart” syndrome: excessive alc or withdrawl*
-> pt young, having drinks, etc”
length categories of AFib
Paroxysmal- Less than 7 days
Persistent- Longer than 7 days
Chronic- Arrhythmias presents for at least 1 year without resolution
3 questions when looking at afib
-hows the rate
-hows the rhythm
-protected from stroke? are they on anticoagulants?
rate categories of afib
Based on ventricular rate:
-Rapid ventricular response: Rate ≥ 100
-Moderate ventricular response: Rate 60-100-
-Slow ventricular response: Rate < 60
“think regular HR”
causes of atrial fibrillation
-Ischemic heart disease *** -> need to r/o CAD first
-Structural heart disease: MC = mitral stenosis
-Alcohol consumption
—
-Hyperthyroidism
-Pheochromocytoma
-Embolism (Pulmonary)
-Sepsis
-Post-operative stress
-Anemia
-Cardiomyopathy
-Electrolyte disturbance
“ayyy ferb (AFib) -> I SHAPE SPACE”
-ischemic hd - CAD
- structural - MC mitral stenosis
- alcohol
- pheochromocytoma
- embolism
-sepsis
-post op stress
-anemia
-cardiomyopathy
-electrolyties
afib treatment acute phase: less than 48 hours
Less than 48 hours from onset -> Synchronized CARDIOVERSION
only do if you are sure about <48h
afib treatment acute phase: Greater than 48 hours
Greater than 48 hours tx:
1) Anticoagulation + rate control for 3 WKS
- clot breaks down in 3 weeks with medication
2) TEE BEFORE CARDIOVERSION:
- visualizes the left atrial appendage and check for clot*
3) Cardioversion
- > cardioversion causes an increased risk of thromboembolic events***
-Ablation therapy
-TEE** = visualizes left atrial appendage
AFib: rate and rhythm control meds
Rate control medication:
-Beta-blockers
-Calcium channel blockers
-Digoxin
Rhythm control medications:
- class 1 and 3 antiarrhythmic medications: amiodarone
Who do we anticoagulate??
based on CHADS2 score vs. CHADSVASC score
Score:
-0 points- none or ASA
-1 point- ASA or full anticoagulation
-2 or greater- full anticoagulation
CHA2DS2VASc score: how to calculate
- C - Congestive heart failure (1 point)
- H - Hypertension (1 point)
- A2 - Age ≥75 years (2 points)
- D - Diabetes Mellitus (1 point)
- S2 - Prior Stroke or TIA or thromboembolism (2 points) -> retinal artery occlusion is a TIA
- V - Vascular disease (prior myocardial infarction, peripheral artery disease, or aortic atheroscleoris) (1 point)
- A - Age 65–74 years (1 point)
- Sc - Sex category (i.e., female gender) (1 point)
If their score is 0 and female: DO not give a point
Score:
-0 points- none or ASA
-1 point- ASA or full anticoagulation
-2 or greater- full anticoagulation
CHA2DS2VASc = percentange risk for stroke in patients with AFib
Warfarin MOA, metabolism, INR goal levels
MOA:
-Blocks vitamin K dependent clotting factors in the liver
- Factors II, VII, IX, and X + Protein C and S
-Can be reversed with Vitamin K or fresh frozen plasma****
- Metabolism: Cytochrome P450
Monitor INR
- Standard goal: 2-3
- pts with mechanical heart valves: 2.5 – 3.5
-> if even goes .1 under -> start over therapy
Warfarin: factors affecting INR
Decreasing INR:
-Leafy green vegetables: spinach, broccoli, brussels sprouts
- Phenytoin
- phenobarbitol
-St. Jonhs wart- OTC supplement
Increasing INR:
-Alcohol
-ANTIBIOTICS: quinolones, amoxicillin, metronidazole
-Amiodarone
-Steroids
INR too high: risk bleeding event
INR too low: risk blood clotting
atrial flutter definition
Rate 250 – 350 bpm (rate of atrium not HR)
-Reentry circuit in the atrium
-*Produces a “SAW-TOOTH” pattern
-Classified as atrial to ventricular conduction ratio
- ex: 3 flutter waves and 1 QRS complex: 3:1 conduction
atrial flutter causes
Causes:
-COPD**
-Cardiomyopathy
-Structural heart disease -Atrial septal defect
-Myocarditis
-Hyperthyroidism
-Idiopathic
-these things just exacerbate the deformity thats already there
“you make my heart flutter i cant BREATHE bc of COPD”
atrial flutter tx
-More successful with ablation therapy -> ablation is tx for life
-Anticoagulation
-Treatment for atrial fibrillation
atrial flutter = reentry circuit in the atrium
“you make my heart flutter, i cant breathe (COPD) -> i need to cut you off (ablation tx) and heal (anticoagulants)”
ventricular tachycardia definition + sustained vs nonsustained
Definition: ventricular rate of 150-250 bpm
-3 of more premature ventricular contractions in a row (PVC)
-Unifocal (monomorphic)
-Multifocal (polymorphic)
Nonsustained vs. sustained
-NSVT: < 30 seconds
-Sustained VT: > 30 seconds -> Even if spontaneous resolution
- if sustained VT -> need a deliberator
torsades de pointes def and treatment
Polymorphic Vtach
-“Twisting of the points”
-QRS complex twists around axis
-Torsades = Warning sign of VFIB
Treatment:
-First line: MAGNESIUM 1g IV push*
-Defibrillation if no pulse
right bundle branch block (RBBB) description and ekg
Electrical impulses are delayed in the right bundle branch
-delayed contraction in right ventricle
“WiLLIAM MaRRoW”
EKG:
-leads V1 and V2*
-RsR complex
-T-wave inversions
right bundle branch block (RBBB) causes and treatment
Causes:
-Increased RIGHT ventricular pressures:
-Cor pulmonale
-PE
-Myocardial ischemia
-Idiopathic
Treatment- Rule out underlying cause
left bundle branch block (LBBB)
Delay occurs in the left bundle branch
-delayed contraction in left ventricle
- usually pathologic
“WiLLIAM MaRRoW”
EKG:
-Leads V5 and V6
-Broadened R wave
-T-wave inversions
-Widened QRS in V1 and V2
left bundle branch block (LBBB) causes and treatment
Causes: Myocardial fibrosing
-HTN
-Myocardial ischemia: LAD **
-Cardiomyopathies
Treatment- Rule out underlying disease; do an ischemic workup
second degree type 1 - wenkebach
-Intermittent block within the AV NODE
-Progressive lengthening of PR interval with eventual non-conducting P wave*
-Caused by conduction arriving at time when AV node is absolutely refectory
“it gets longer and longer till you get a wenkebach”
Tx: none required unless sx
- eventually there is a p wave with no QRS
