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

Cardiac Arrhythmias.ppt

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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

Bradycardia-tachycardia syndrome.ppt

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Arrhythmias and EKGs

Arrhythmias and EKGs

Outline
* Sinus Arrhythmia and Sick Sinus Syndrome
* Multifocal Atrial Tachycardia
* Bigeminal Rhythms
* Preexcitation and AVRT

Mechanisms of Arrhythmogenesis
Sinus Arrhythmia
EKG Characteristics: Presence of sinus P waves
Variation of the PP interval which cannot be q attributed to either SA nodal block or PACs

When the variations in PP interval occur in phase with respiration, this is considered to be a normal variant. When they are unrelated to respiration, they may be caused by the same etiologies leading to sinus bradycardia.

Sick Sinus Syndrome
* Characterized by a collection of symptoms and ECG findings due to chronic dysfunction of the sinoatrial (SA) node:
o Chronic and severe sinus bradycardia
o Sinus pauses
o Sinus arrhythmia
o Complete sinus arrest
o Progressive development of atrial arrhythmias (a-flutter, a-fib, atrial tachycardia)
* Patients are usually elderly and present with lightheadedness and/or syncope, but it can also manifest as angina, dyspnea, and palpitations.

* About 50% of people with SSS also display some degree of dysfunction of the AV node
Sinus bradycardia (rate of ~43 bpm) with a sinus pause

Etiologies of Sick Sinus Syndrome
Familial SSS (due to mutations in SCN5A)
Infiltrative diseases
Pericarditis
Lyme disease
Hypothyroidism
Rheumatic fever
Sinus node firbosis
Atherosclerosis of the SA artery
Congenital heart disease
Excessive vagal tone
Drugs
Tachycardia-Bradycardia Syndrome
* Common variant of sick sinus syndrome severe bradycardia alternates with paroxysmal tachycardias, most often atrial fibrillation.
* There is usually a prolonged pause in the cardiac rhythm following cessation of the tachyarrhythmia.
Tachycardia-Bradycardia Syndrome
Abrupt termination of atrial flutter with variable AV block, followed by sinus arrest with a junctional escape beat.

Multifocal Atrial Tachycardia
Bigeminal Rhythms
* Arrhythmias in which each normal sinus beat is followed by a premature contraction (PAC, PJC, or PVC).
* Results in a couplet rhythm which can be detected by pulse or auscultation.
* Generally benign
Atrial Bigeminy
Ventricular Bigeminy
Preexcitation
ECG Characteristics of WPW:
1. Short PR interval
2. QRS prolongation
3. Delta wave
Preexcitation is a condition characterized by an accessory pathway of conduction, which allows the heart to depolarize in an atypical sequence.
The most common form of preexcitation is called Wolfe-Parkinson-White (WPW) syndrome, in which a direct atrioventricular connection allows the ventricles to begin depolarization while the standard action potential is still traveling through the AV node.

AV Reentrant Tachycardia (AVRT)
In patients with WPW, a reentrant rhythm can be generated where the AV node serves as one arm of the reentrant circuit, and the accessory pathway as the other.

Types of AVRT
* Orthodromic AVRT (More common) – Narrow complex tachycardia in which the wave of depolarization travels down the AV node and retrograde up the accessory pathway.
* Antidromic AVRT (Less common) – Wide complex tachycardia in which the wave of depolarization travels down the accessory pathway and retrograde up the AV node.

Mechanism of orthodromic AVRT
Mechanism of antidromic AVRT
What is this arrhythmia?
Antidromic AVRT
Classification Scheme for Arrhythmias

Arrhythmias and EKGs.ppt

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