Cardiology: Cardiac Rhythm Disturbances

First line to evaluate Rhythm

EKG

EP Study

- invasive catheter based test that maps the heart's electrical activity

- electrode catheters are advanced through a vein into the heart

- records electrical signals from inside the heart

EP Study: Evaluates (4)

- location and mechanism of an arrhythmia

- SA and AV node/conduction system

- presence of an accessory pathway

- ability to induce an arrhythmia under controlled conditions

EP Study ID (4)

- recurrent or unexplained SVT

- suspected AVNRT or AVRT/WPW

- selected wide complex tachycardias

- when catheter ablation is being considered

Catheter Ablation

- minimally invasive procedure used to eliminate abnormal electrical pathways or arrhythmia-producing tissue

- radiofrequency energy, cryotherapy, or other energy sources are used to ablate the target tissue

What should be done before a Catheter Ablation?

EP Study first to find the electrical problem

Catheter Ablation ID (6)

- AVNRT

- AVRT/WPW

- A. Flutter

- Focal atrial tachycardia

- A. Fib

- V. Tachycardia

Catheter Ablation: AVNRT where to ablate

Ablate the slow pathway

Catheter Ablation: AVRT/WPW where to ablate

Ablate the accessory pathway

Catheter Ablation: A. Flutter where to ablate

Ablate the reentry circuit

Catheter Ablation: Focal Atrial Tachycardia where to ablate

Ablate the ectopic focus

Catheter Ablation: A.Fib usually involve

Pulmonary vein isolation (PVI)

4 Mechanisms of Arrhythmias

1. Abnormal Automaticity

2. Abnormal Impulse Conduction

3. Reentry

4. Triggered Activity

Abnormal Automaticity (3)

- cardiac cells fire when they shouldn't

- creates an abnormal/ectopic pacemaker

- PACs, PVCs, focal atrial tachycardia

Abnormal Impulse Conduction (2)

- electrical impulse if delayed of blocked

- AV blocks, BBB

Reentry (2)

- electrical impulse travels in a continuous loop, repeatedly reactivating tissue

- AVNRT, AVRT/WPW, A. Flutter

Triggered Activity (3)

- extra impulse occurs after the normal action potential

- electrolyte abnormalities, medications, or prolonged QT

- torsades de pointes

Rhythm Interpretation 5 Steps

1. Rate

2. Rhythm

3. P waves

4. PR Interval

5. QRS

No clear P waves + irregularly irregular

A. Fib

Sawtooth Waves

A. Flutter

Regular narrow-complex tachycardia

SVT (AVNRT)

Wide-complex tachycardia

V-tach

Progressively longer PR w/ dropped QRS

Mobitz 1 Heart block

Fixed PR + sudden dropped QRS

Mobitz 2 Heart block

P waves and QRS march independently

Complete heart block (III)

Polymorphic VT + prolonged QT

Torsades

Sinus Dysrhythmias (4)

- Sinus tachycardia

- Sinus bradycardia

- Sinus arrhythmia

- Sick Sinus Syndrome (SSS)

Sinus Tachycardia EKG (4)

- rate > 100bpm

- regular rhythm

- normal sinus P wave before every QRS

- usually gradual onset

Sinus Tachycardia Causes (6)

- exercise, pain, anxiety

- dehydration, hemorrhage, anemia, hypoxia

- fever, infection

- HF, PE

- hyperthyroidism

- caffeine, meds

Sinus Tachycardia tx

Find and treat the underlying cause

Sinus Bradycardia EKG (4)

- rate

Sinus Bradycardia Causes (4)

- athletes, sleep, increased vagal tone

- medications

- sinus node dysfunction, ischemia

- hypothyroidism, hypothermia, OSA

Sinus Bradycardia tx asx

No treatment

Sinus Bradycardia tx sx

identify and correct reversible cause

Sinus Bradycardia compromise initial tx (4)

- assess airway and breathing: O2/ventilation prn

- cardiac monitoring and IV access

- obtain EKG

- Identify and tx reversible causes

Sinus Bradycardia Compromise tx

Atropine

Sinus Bradycardia Compromise if tx ineffective (3)

- Transcutaneous pacing (TCP)

and/or

- Dopamine infusion or epinephrine infusion

- expert consult and transvenous pacin

Atropine MOA

- blocks parasympathetic (vagal) effects on the heart

- increase SA node firing; improve AV nodal conduction

- increases HR

Atropine Dosing (3)

- 1mg IV bolus

- repeat every 3-5 min

- max total dose: 3mg

Atropine ADE (6)

- tachycardia

- palpitations

- dry mouth

- blurred vision

- urinary retention

- confusion (older adults)

When can Atropine be ineffective?

In significant infranodal conduction disease

Transcutaneous Pacing (TCP)

- temporary external cardiac pacing through defibrillator/pacing pads

- used as bridge until cause is corrected or more definitive pacing is available

- select pacer mode, start low (60-80) and gradually increase up

Transcutaneous Pacing (TCP) ID

When sx bradycardia persists despite atropine; persistent instability

Is Transcutaneous Pacing (TCP) painful?

It can be painful in a conscious patient

Sinus Arrhythmia EKG (4)

- normal sinus P wave before every QRS

- irregular rhythm associated with respiration

- HR increases with inspiration

- HR decreases with expiration

Sinus Arrhythmia causes (3)

- normal physiologic variation

- increased vagal tone

- mc in children and young healthy adults

Sinus Arrhythmia tx

None; reassurance

Sick Sinus Syndrome (sinus node dysfunction) EKG (4)

- sinus bradycardia

- sinus pauses/arrest

- tachy-brady syndrome

- chronotropic incompetence (inadequate HR increase with activity)

Sick Sinus Syndrome Causes (7)

- age related fibrosis of the sinus node (mc)

- ischemic heart disease

- infiltrative disease

- prior cardiac surgery

- medications that suppress sinus-node fx

- metabolic/endocrine abnormalities

- OSA

Sick Sinus Syndrome tx (2)

- identify and correct reversible causes

- if sx: permanent pacemaker

Sick Sinus Syndrome

What is

Sick Sinus Syndrome

What is

Premature Atrial Complexes (PAC) EKG (5)

- premature beat originating in the atria

- early P wave with a different morphology than the sinus P wave

- normal/narrow QRS

- followed by a brief, noncompensatory pause

- underlying rhythm may be regular

Premature Atrial Complexes (PAC) Causes (7)

- often occur in healthy adults

- increased sympathetic activity/stress

- caffeine, alcohol, tobacco, stimulants

- electrolyte abnormalities

- hypoxis

- hyperthyroidism

- structural heart dz/atrial enlargement

Premature Atrial Complexes (PAC) sx (2)

- often asymptomatic

- palpitations or sensation of a "skipped beat"

Premature Atrial Complexes (PAC) tx (4)

- usually no tx needed

- identify and correct triggers/causes

- frequent/sx: B-Blocker

- frequent may warrant evaluation for underlying heart dz or atrial arrhythmias

2 Types of Tachycardias

1. Narrow Complex

2. Wide Complex

Narrow Complex Tachycardias (5)

- sinus tachycardia

- Suptraventricular tachycardias (AVNRT/AVRT)

- A. Fib

- A. Flutter

- Multifocal Atrial Tachycardia

Wide Complex Tachycardias (4)

- SVT with aberrancy

- SVT with preexcitation (WPW)

- V. Tachycardia

- V. Fib

Supraventricular Tachycardia (SVT)

What is

Supraventricular Tachycardia (SVT)

- rapid rhythm originating above the ventricles

- regular, narrow complex

- AVNRT (mc) or AVRY

- suddent onset and termination

Regular + Narrow + Fast: What should you think

Supraventricular Tachycardia (SVT)

Supraventricular Tachycardia (SVT) sx (5)

- palpitations

- dyspnea

- chest discomfort

- lightheadedness/dizziness

- syncope (severe)

Supraventricular Tachycardia (SVT) EKG (5)

- regular rhythm

- narrow QURS (

Supraventricular Tachycardia (SVT) Stable tx (2)

- vagal maneuvers

- adenosine 6mg rapid IV push + NS flush

Supraventricular Tachycardia (SVT) if tx unsuccessul

Adenosine 12mg rapid IV push + flush

Supraventricular Tachycardia (SVT) is persistent tx

B-Blocker or diltiazem/verapamil

Supraventricular Tachycardia (SVT): recurrent sx SVT tx

Catheter ablation

Supraventricular Tachycardia (SVT) Unstable tx

Synchronized cardioversion (50-100 J) (electrocute them)

Atrial Fibrillation EKG (5)

- irregularly irregular rhythm

- no distinct P waves

- variable R-R intervals

- QRS usually narrow

- V rate is variable; > 100bpm

Atrial Fibrillation Causes (8)

- increasing age

- HTN/DM

- CAD/HF

- Valvular heart disease; mitral dz

- Obesity/OSA

- hyperthyroidism

- alcohol use

- pulmonary dz

Atrial Fibrillation sx (6)

- may be asymptomatic

- palpitations

- fatigue/exercise intolerance

- dyspnea

- lightheadedness

- chest discomfort

Atrial Fibrillation Complications (3)

- thromboembolism/stroke

- HF

- tachycardia mediated cardiomyopathy

Atrial Fibrillation tx (4)

- assess hemodynamic stability first

- rate or rhythm control

- assess need for anticoagulation based on stroke risk

- tx contributing conditions/risks

Paroxysmal Atrial Fibrillation

- terminates spontaneously or with intervention within ≤ 7 dyas

- episodes may recur

Persistent Atrial Fibrillation

- continuous for > 7 days

- often requires rhythm control

Longstanding persistent Atrial Fibrillation

- continuous for >12mo

- rhythm-control strategy

Permanent Atrial Fibrillation

- joint decision to stop attempts to restore/maintain sinus rhythm

- AF accepted

- rate control and stroke prevention

- not defined by a specific duration

Atrial Fibrillation Evaluation

- EKG (initial)

- Labs

- Imaging

- TEE

Atrial Fibrillation Labs (5)

- CBC

- BMP/CMP

- Mg

- TSH

- Troponin is ischemia/ACS suspected

Atrial Fibrillation Imaging (2)

- CXR

- Echo (TTE)

Atrial Fibrillation Unstable tx

Synchronized cardioversion

Atrial Fibrillation Stable Management

- identify and treat contributing causes

- control sx (rate or rhythm)

- assess stroke risk

- admit or outpatient management

If long term anticoagulation is contraindicated, what should you consider?

Left Atrial Appendage Occlusion (LAAO)

Atrial Fibrillation: Rhythm Control ID (4)

- sx AF despite adequate rate

- recently dx AF

- tachycardia-mediated cardiomyopathy

- HF when AF is contributing to sx/LV dysfunction

Atrial Fibrillation: Rhythm Control options (3)

- electrical cardioversion

- antiarrhythmic medications

- catheter ablation/pulmonary vein isolation

Atrial Fibrillation: Rhythm Control Medications (7)

- amiodarone

- flecainide

- propafenone

- sotalol

- dofetilide

- dronedarone

Atrial Fibrillation: Rate Control tx (3)

- Beta Blocker (metoprolol tartrate)

- Diltiazem or Verapamil

- Digoxin

What patient population is rate control preferred in?

Older patients ≥75-80yo

How to assess stroke risk

CHA2DS2-VASc

CHA2DS2-VASc

C-Chronic Heart Failure (1)

H-HTN (1)

A - Age > 75 years (2)

D-Diabetes Mellitus (1)

S-Stroke/TIA (2)

V-Vascular disease (1)

A - Age 65- 74 years (1)

Sc-Gender: Female (1)

CHA2DS2-VASc Low risk

- 0 to 1

- no anticoagulation

CHA2DS2-VASc Intermediate risk

- 1 to 2

- reasonable to anticoagulated/consider

CHA2DS2-VASc High risk

- men: ≥2

- women: ≥3

- anticoagulation recommended

Atrial Fibrillation: Stroke Medications (2)

- DOACs

- Warfarin

What stroke medication is preferred for most patients with A. Fib?

DOACs

DOACs (3)

- Apixaban

- Rivaroxaban

- Dabigatran

Warfarin ID (2)

- mechanical heart valve

- moderate-severe rheumatic mitral stenosis

Oral Anticoagulation major AE

Bleeding

AF + PCI tx (5)

- anticoagulation for AF and antiplatelet therapy for stent

- DOAC + ASA + clopidogrel (1-4wks)

- then DOAC + clopidogrel for up to 12mo

- after 12mo: DOAC alone

- DOAC and clopidogrel preferred