Arrhythmia

ARRHYTHMIA
Edited by Yingmin Chen

* Definition of Arrhythmia:
The Origin, Rate, Rhythm, Conduct velocity and sequence of heart activation are abnormally.

Anatomy of the conducting system
Pathogenesis and Inducement of Arrhythmia
* Some physical condition
* Pathological heart disease
* Other system disease
* Electrolyte disturbance and acid-base imbalance
* Physical and chemical factors or toxicosis


Mechanism of Arrhythmia
* Abnormal heart pulse formation
* Sinus pulse
* Ectopic pulse
* Triggered activity
* Abnormal heart pulse conduction
* Reentry
* Conduct block

Classification of Arrhythmia
* Abnormal heart pulse formation
* Sinus arrhythmia
* Atrial arrhythmia
* Atrioventricular junctional arrhythmia
* Ventricular arrhythmia
* Abnormal heart pulse conduction
* Sinus-atrial block
* Intra-atrial block
* Atrio-ventricular block
* Intra-ventricular block
* Abnormal heart pulse formation and conduction

Diagnosis of Arrhythmia
* Medical history
* Physical examination
* Laboratory test

Therapy Principal
* Pathogenesis therapy
* Stop the arrhythmia immediately if the hemodynamic was unstable
* Individual therapy

Anti-arrhythmia Agents
* Anti-tachycardia agents
* Anti-bradycardia agents
Anti-tachycardia agents
* Modified Vaugham Williams classification
* I class: Natrium channel blocker
* II class: ß-receptor blocker
* III class: Potassium channel blocker
* IV class: Calcium channel blocker
* Others: Adenosine, Digital

Anti-bradycardia agents
* ß-adrenic receptor activator
* M-cholinergic receptor blocker
* Non-specific activator

Clinical usage
Anti-tachycardia agents:
* Ia class: Less use in clinic
* Guinidine
* Procainamide
* Disopyramide: Side effect: like M-cholinergic receptor blocker

Anti-tachycardia agents:
* Ib class: Perfect to ventricular tachyarrhythmia
1. Lidocaine
2. Mexiletine
Anti-tachycardia agents:
* Ic class: Can be used in ventricular and/or supra-ventricular tachycardia and extrasystole.

1. Moricizine
2. Propafenone

Anti-tachycardia agents:
* II class: ß-receptor blocker
* Propranolol: Non-selective
* Metoprolol: Selective ß1-receptor blocker, Perfect to hypertension and coronary artery disease patients associated with tachyarrhythmia.
* III class: Potassium channel blocker, extend-spectrum anti-arrhythmia agent.
* Amioarone: Perfect to coronary artery disease and heart failure patients
* Sotalol: Has ß-blocker effect
* Bretylium
* IV class: be used in supraventricular tachycardia
* Verapamil
* Diltiazem
* Others:
Adenosine: be used in supraventricular tachycardia

Anti-bradycardia agents
* Isoprenaline
* Epinephrine
* Atropine
* Aminophylline
Proarrhythmia effect of antiarrhythmia agents
* Ia, Ic class: Prolong QT interval, will cause VT or VF in coronary artery disease and heart failure patients
* III class: Like Ia, Ic class agents
* II, IV class: Bradycardia

Non-drug therapy
* Cardioversion: For tachycardia especially hemodynamic unstable patient
* Radiofrequency catheter ablation (RFCA): For those tachycardia patients (SVT, VT, AF, AFL)
* Artificial cardiac pacing: For bradycardia, heart failure and malignant ventricular arrhythmia patients.

Sinus Arrhythmia

Sinus tachycardia
* Sinus rate > 100 beats/min (100-180)
* Causes:
* Some physical condition: exercise, anxiety, exciting, alcohol, coffee
* Some disease: fever, hyperthyroidism, anemia, myocarditis
* Some drugs: Atropine, Isoprenaline
* Needn’t therapy
Sinus Bradycardia
* Sinus rate < 60 beats/min
* Normal variant in many normal and older people
* Causes: Trained athletes, during sleep, drugs (ß-blocker) , Hypothyriodism, CAD or SSS
* Symptoms:
* Most patients have no symptoms.
* Severe bradycardia may cause dizziness, fatigue, palpitation, even syncope.
* Needn’t specific therapy, If the patient has severe symptoms, planted an pacemaker may be needed.
Sinus Arrest or Sinus Standstill
* Sinus arrest or standstill is recognized by a pause in the sinus rhythm.
* Causes: myocardial ischemia, hypoxia, hyperkalemia, higher intracranial pressure, sinus node degeneration and some drugs (digitalis, ß-blocks).
* Symptoms: dizziness, amaurosis, syncope
* Therapy is same to SSS
Sinoatrial exit block (SAB)
* SAB: Sinus pulse was blocked so it couldn’t active the atrium.
* Causes: CAD, Myopathy, Myocarditis, digitalis toxicity, et al.
* Symptoms: dizziness, fatigue, syncope
* Therapy is same to SSS

Sinoatrial exit block (SAB)
* Divided into three types: Type I, II, III
* Only type II SAB can be recognized by EKG.

Sick Sinus Syndrome (SSS)
* SSS: The function of sinus node was degenerated. SSS encompasses both disordered SA node automaticity and SA conduction.
* Causes: CAD, SAN degeneration, myopathy, connective tissue disease, metabolic disease, tumor, trauma and congenital disease.
* With marked sinus bradycardia, sinus arrest, sinus exit block or junctional escape rhythms
* Bradycardia-tachycardia syndrome

Sick Sinus Syndrome (SSS)
* EKG Recognition:
* Sinus bradycardia, ≤40 bpm;
* Sinus arrest > 3s
* Type II SAB
* Nonsinus tachyarrhythmia ( SVT, AF or Af).
* SNRT > 1530ms, SNRTc > 525ms
* Instinct heart rate < 80bmp

Sick Sinus Syndrome (SSS)
* Therapy:
* Treat the etiology
* Treat with drugs: anti-bradycardia agents, the effect of drug therapy is not good.
* Artificial cardiac pacing.

Atrial arrhythmia
Premature contractions
* The term “premature contractions” are used to describe non sinus beats.
* Common arrhythmia
* The morbidity rate is 3-5%
Atrial premature contractions (APCs)
* APCs arising from somewhere in either the left or the right atrium.
* Causes: rheumatic heart disease, CAD, hypertension, hyperthyroidism, hypokalemia
* Symptoms: many patients have no symptom, some have palpitation, chest incomfortable.
* Therapy: Needn’t therapy in the patients without heart disease. Can be treated with ß-blocker, propafenone, moricizine or verapamil.

Atrial tachycardia
* Classify by automatic atrial tachycardia (AAT); intra-atrial reentrant atrial tachycardia (IART); chaotic atrial tachycardia (CAT).
* Etiology: atrial enlargement, MI; chronic obstructive pulmonary disease; drinking; metabolic disturbance; digitalis toxicity; electrolytic disturbance.........

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Cardiac Arrhythmias

Cardiac Arrhythmias
By:Elise Georgi Morris, M.D.

Objectives
* Identify common arrhythmias encountered by the family physician
* Discuss arrhythmia etiologies
* Discuss initial primary care work-up and treatment
* Practice questions

Normal Sinus Rhythm
Implies normal sequence of conduction, originating in the sinus node and proceeding to the ventricles via the AV node and His-Purkinje system.
EKG Characteristics: Regular narrow-complex rhythm

Sinus Bradycardia
* HR< 60 bpm; every QRS narrow, preceded by p wave
* Can be normal in well-conditioned athletes
* HR can be<30 bpm in children, young adults during sleep, with up to 2 sec pauses

Sinus bradycardia--etiologies
* Normal aging
* 15-25% Acute MI, esp. affecting inferior wall
* Hypothyroidism, infiltrative diseases
(sarcoid, amyloid)
* Hypothermia, hypokalemia
* SLE, collagen vasc diseases
* Situational: micturation, coughing
* Drugs: beta-blockers, digitalis, calcium channel blockers, amiodarone, cimetidine, lithium

Sinus bradycardia--treatment
* No treatment if asymptomatic
* Sxs include chest pain (from coronary hypoperfusion), syncope, dizziness
* Office: Evaluate medicine regimen—stop all drugs that may cause
* Bradycardia associated with MI will often resolve as MI is resolving; will not be the sole sxs of MI
* ER: Atropine if hemodynamic compromise, syncope, chest pain
* Pacing

Sinus tachycardia
* HR > 100 bpm, regular
* Often difficult to distinguish p and t waves

Sinus tachycardia--etiologies
* Fever
* Hyperthyroidism
* Effective volume depletion
* Anxiety
* Pheochromocytoma
* Sepsis
* Anemia
* Exposure to stimulants (nicotine, caffeine) or illicit drugs
* Hypotension and shock
* Pulmonary embolism
* Acute coronary ischemia and myocardial infarction
* Heart failure
* Chronic pulmonary disease
* Hypoxia

Sinus Tachycardia--treatment
* Office: evaluate/treat potential etiology :check TSH, CBC, optimize CHF or COPD regimen, evaluate recent OTC drugs
* Verify it is sinus rhythm
* If no etiology is found and is bothersome to patients, can treat with beta-blocker

Sinus Arrhythmia
* Variations in the cycle lengths between p waves/ QRS complexes
* Will often sound irregular on exam
* Normal p waves, PR interval, normal, narrow QRS

Sinus arrhythmia
* Usually respiratory--Increase in heart rate during inspiration
* Exaggerated in children, young adults and athletes—decreases with age
* Usually asymptomatic, no treatment or referral
* Can be non-respiratory, often in normal or diseased heart, seen in digitalis toxicity
* Referral may be necessary if not clearly respiratory, history of heart disease

Sick Sinus Syndrome
* All result in bradycardia
* Sinus bradycardia (rate of ~43 bpm) with a sinus pause
* Often result of tachy-brady syndrome: where a burst of atrial tachycardia (such as afib) is then followed by a long, symptomatic sinus pause/arrest, with no breakthrough junctional rhythm.

Sick Sinus Syndrome--etiology
* Often due to sinus node fibrosis, SNode arterial atherosclerosis, inflammation (Rheumatic fever, amyloid, sarcoid)
* Occurs in congenital and acquired heart disease and after surgery
* Hypothyroidism, hypothermia
* Drugs: digitalis, lithium, cimetidine, methyldopa, reserpine, clonidine, amiodarone
* Most patients are elderly, may or may not have symptoms

Sick sinus syndrome--treatment
* Address and treat cardiac conditions
* Review med list, TSH
* Pacemaker for most is required

Paroxysmal Supraventricular Tachycardia
* Refers to supraventricular tachycardia other than afib, aflutter and MAT
* Occurs in 35 per 100,000 person-years
* Usually due to reentry—AVNRT or AVRT

PSVT
* Initial eval: Is the patient stable?
* Determine quickly if sinus rhythm
* If not sinus and unstable, cardioversion
* Unstable sinus tachycardia---IV beta-blocker, and treat cause
* Sxs of instability would include: chest pain, decreased consciousness, short of breath, shock, hypotension—unstable sxs require shock
* If stable, determine whether regular rhythm (sinus or PSVT) vs irregular (afib/flutter, MAT)? p waves (MAT vs. AF)?
* If regular, determine whether p waves are present, if can’t see---administer adenosine (6mg, can give 2 doses) or CSM or other vagal maneuvers)

* CSM or adenosine commonly terminate the arrhythmia, esp, AVRT or AVNRT
* Can also use CCB or beta blockers to terminate, if available
* Counsel to avoid triggers, caffeine, Etoh, pseudoephedrine, stress
* No p waves —junctional tachycardia, AVRT or AVNRT, Afib
* AVRT and AVNRT: can have retrograde p waves and short RP interval
* Abnormal p waves morphology: MAT

Atrial Fibrillation
* Irregular rhythm
* Absence of definite p waves
* Narrow QRS
* Can be accompanied by rapid ventricular response

Atrial Fibrillation—causes and associations
* Hypertension
* Hyperthyroidism and subclinical hyperthyroidism
* CHF (10-30%), CAD
* Uncommon presentation of ACS
* Mitral and tricuspid valve disease
* Hypertrophic cardiomyopathy
* COPD
* OSA
* ETOH
* Caffeine
* Digitalis
* Familial
* Congenital (ASD)

Atrial fibrillation--assessment
* H & P—assess heart rate, sxs of SOB, chest pain, edema (signs of failure)
* If unstable, need to cardiovert
* Echocardiogram to evaluate valvular and overall function
* Check TSH
* Assess for RVR
* Assess onset of sxs—in the last 24-48 hours? Sudden onset? Or no sxs?

Atrial fibrillation--management
* Rhythm vs Rate control—if onset is within last 24-48 hours, may be able to arrange cardioversion—use heparin around procedure
* Need TEE if valvular disease (high risk of thrombus)
* If unable to definitely conclude onset in last 24-48 hours: need 4-6 weeks of anticoagulation prior to cardioversion, and warfarin for 4-12 weeks after

Atrial Fibrillation
* Cardioversion: synchronized (w/QRS) delivery of current to heart; depolarizes tissue in a reentrant circuit; afib involves more cardiac tissue, but cardiovert
* Defibrillation: non-synchronized delivery of current

Atrial fibrillation--management
* Rate control with chronic anticoagulation is recommended for first line approach for majority of patients; overall Afib is a stable rhythm
* Beta-blockers (atenolol and metoprolol) or calcium channel blockers (verapamil or diltiazem) recommended. Digoxin not recommended for rate control
* Anticoagulation: LMWH and then warfarin; can use aspirin for anticoagulation if CI to warfarin, not as effective

Atrial fibrillation--management
* Goal INR of 2.5 (2.0-3.0)
* Rhythm control---second line approach, if unable to control rate or pt with persistent sxs
* Can also consider radiofrequency ablation at pulm veins
* P wave from another atrial focus
* Occurs earlier in cycle
* Different morphology of p wave
* Benign, common cause of perceived irregular rhythm
* Can cause sxs: “skipping” beats, palpitations
* No treatment, reassurance
* With sxs, may advise to stop smoking, decrease caffeine and ETOH
* Can use beta-blockers to reduce frequency

1st Degree AV Block
* PR interval >200ms
* If accompanied by wide QRS, refer to cardiology, high risk of progression to 2nd and 3rd deg block
* Otherwise, benign if asymptomatic

2nd Degree AV Block Mobitz type I (Wenckebach)

* Progressive PR longation, with eventual non-conduction of a p wave
* May be in 2:1 or 3:1
Wenckebach, Mobitz type I
* Usually asymptomatic, but with accompanying bradycardia can cause angina, syncope esp in elderly—will need pacing if sxs
* Also can be caused by drugs that slow conduction (BB, CCB, dig)
* 2-10% long distance runners
* Correct if reversible cause, avoid meds that block conduction

2nd degree block Type II (Mobitz 2)
* Normal PR intervals with sudden failure of a p wave to conduct
* Usually below AV node and accompanied by BBB or fascicular block
* Often causes pre/syncope; exercise worsens sxs
* Generally need pacing, possibly urgently if symptomatic

3rd Degree AV Block

* Complete AV disassociation, HR is a ventricular rate
* Will often cause dizziness, syncope, angina, heart failure
* Can degenerate to Vtach and Vfib
* Will need pacing, urgent referral
* Extremely common throughout the population, both with and without heart disease
* Usually asymptomatic, except rarely dizziness or fatigue in patients that have frequent PVCs and significant LV dysfunction
* No treatment is necessary, risk outweighs benefit
* Reassurance
* Optimize cardiac and pulmonary disease management

Non-sustained Ventricular tachycardia
* Defined as 3 or more consecutive ventricular beats
* Rate of >120 bpm, lasting less than 30 seconds
* May be discovered on Holter, or other exercise testing

Non-sustained ventricular tachycardia
* Need to exclude heart disease with Echo and stress testing
* If normal, there is no increased risk of death
* May need anti-arrhythmia treatment if sxs
* In presence of heart disease, increased risk of sudden death
* Need referral for EPS and/or prolonged Holter monitoring

Ventricular fibrillation
* Defibrillation

Practice Questions—Case studies

References

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Bradycardia-tachycardia syndrome

Bradycardia-tachycardia syndrome
By: Presented by Ri

Sick sinus syndrome

* Multiple manifestations on EKG
* Sinus bradycardia
* Sinus arrest
* Sinoatrial block
* Bradycardia –tachycardia syndrom

Bradycardia-tachycardia syndrome

* Alternating patterns of bradycardia and tachycardia
* Often there is a long pause (asystole) between heartbeats, especially after an episode of tachycardia
* Tachycardia: PSVT, atrial fibrillation, atrial flutter

causes

* Most cases are idiopathic
* Intrinsic causes
* Extrinsic causes
* Cardiac surgery, especially to the atria, is a common cause of sick sinus syndrome in children.

Clinical manifestations

* Many people with sick sinus syndrome have no symptoms
* Symptoms are related to the decresed cardiac output that occurs with the bradyarrythmias or tachyarrythmias
* Fainting , Fatigue , Shortness of breath, or dyspnea, Chest pains , Confusion , Palpitations
* Bradycardia-tachycardia syndrome: peripheral thromboembolism and stroke

Treatment

* If the disorder is asymptomatic (without symptoms), no treatment is necessary
* Bradycardia-tachycardia syndrome
* Associated tachycardia may be treated with medications after the person is protected from symptomatic bradycardia by a pacemaker.
* Warfarin has been shown to decrease the number of strokes and embolic events

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