arrhythmia overview

8/12/2019 Arrhythmia Overview

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Arrhythmia Overview

Antonia Anna Lukito


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Arrhythmia

Heart rhythm disorders (arrhythmias) areproblems that affect the electrical system, or"wiring," of the heart muscle. Heartarrhythmias are very common and nearlyeveryone will experience an abnormal heartrhythm some time during their lives. Most

are not serious.


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Categorization

Arrhythmias can be categorized in threemain ways:

the rate (too slow or too fast); the location (ventricles-lower chambers

of heart or atria-upper chambers); and

the beat (steady or chaotic andirregular).


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Types of Heart Rhythm Disorders

Bradycardia

Tachycardia Premature Heart Beat

Fibrillation


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Bradycardia

Describes a heartbeat that is too slow (less than 60beats a minute).

A normal heart contracts about 100,000 times eachday, at a rate of 60 to 100 times a minute.

The weak pace may mean the heart doesn't beatoften enough to ensure blood flow.

Slow heart rates can be the result of certain

medications, congenital heart disease, or thedegenerative processes of aging.

Heart block (or AV Block) and Sick Sinus Syndromeare forms of bradycardia.


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Tachycardia (tachy =fast) is a too-rapid heartbeat. There are two predominant types of tachycardia:

supraventricular tachycardia (SVT) and ventriculartachycardia (VT).

The most common type of SVT is atrial fibrillation, anirregular and rapid heartbeat in the upper chambers of theheart (or atria).

At times, ventricular tachycardia (VT) can change withoutwarning into a deadly arrhythmia called ventricular

fibrillation (VF). It is the number one cause of sudden cardiac arrest. Within

seconds, an individual loses consciousness and, withoutimmediate emergency treatment, will die within minutes.


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Premature Heart Beat

Occurs when the heart's regular rhythm isinterrupted by early or premature beats.

It may feel as if the heart has skipped a beat.

Usually it is not serious. If the beat arises from locations in the atria

(upper chambers) it is called premature atrialbeat.

Premature ventricular beats (also calledpremature ventricular contractions or PVCs)arise from the ventricles (lower chambers).


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Fibrillation

Describes a heartbeat that is chaotic, orirregular, and may seem to skip beats or beatout of rhythm. This occurs when a chamberof the heart goes into spasm and fails topump.

There are two types of fibrillation: atrialfibrillation and ventricular fibrillation


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Treatment Options

Lifestyle Changes Medications

Cardiac Ablation Electronic Devices

Implanted Cardioverter Defibrillators (ICDs)

Pacemakers Devices for Heart Failure

Surgery


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Lifestyle Changes

Since other heart disorders increase the riskof developing arrhythmias, lifestyle changesoften are recommended.

In addition, improving health can lesson thesymptoms of arrhythmias and other heartdisorders as well as prove beneficial tooverall patient health


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Medications

Medications can control abnormal heartrhythms or treat related conditions such ashigh blood pressure, coronary artery disease,heart failure, and heart attack.

Drugs also may be administered to reducethe risk of blood clots in patients with certaintypes of arrhythmias


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MANAGEMENT OF TACHY-ARRHYTHMIAS

Tachyarrhythmia Supraventricular Paroxysmal supraventricular tachycardias Atrial fibrillation

Atrial flutter Multifocal atrial tachycardia Junctional tachycardia Sinus tachycardia

Ventricular Ventricular tachycardia ( 5 beats at 120 bpm; non-

sustained 30s; monomorphic, polymorphic;with pulse, pulseless)

Ventricular fibrillation


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MANAGEMENT OF TACHY-ARRHYTHMIAS

DiagnosisObtain a 12-lead ECGEcho may be necessary to exclude structural heart disease? invasive electrophysiological study

Acute treatmentIf in doubt and patient, treat as VT. If patient haemodynamically unstable,

immediate DC cardioversion/defibrillationActive seek out and treat causes (acute coronary syndrome, acute

respiratory insufficiency of various aetiologies, sepsis, electrolytes)Correct electrolytes : keep serum K > 4 mmol/L and Mg > 2 mmol/L


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Narrow Complex Tachy-arrhythmias

Haemodynamic unstableImmediate DC cardioversion (50J for PSVT/A flutter; 200J for AF)

Haemodynamic stable Vagal maneouvres

Carotid Massage IV adenosine 6 mg (ATP=10mg) ---2 min---6 mg(10)---2 min---12 mg(20) IV Verapamilm 5mg over 3-5 mins, to maximum 15 mg IV Amiodarone (loading dose of 150mg over 10 mins, may repeat if failed to rate control;

followed by infusion 30 mg/hour) caution side effectsIf failed to rate-control with amiodarone may consider other anti-arrhythmics eg Diltiazem (0.25 to 0.35 mg/kg loading followed by infusion 5-15 mg/hour) caution

hypotension IV Beta - blockers (metoprolol titrate 0.5-1mg, esmolol 0.5mg/kg/min for one min followed by

0.05-0.2mg/kg/min) caution hypotension IV Digoxin (1 mg over 24 hours in increments of 0.25 to 0.5 mg, followed by 0.125 mg to 0.25

mg daily)


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Wide Complex Tachy-arrhythmias

Haemodynamic unstableImmediate DC cardioversion start at 100J, increase if

unsuccessful

Defibrillation according to ACLS protocol for VF and pulselessVT

Haemodynamic stableSVT (see above)

VT or uncertain IV Amiodarone (loading dose of 150mg over 10 mins, may repeat if

failed to rate control; followed by infusion 30 mg/hour)


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Bradyarrhythmia

Heart rate < 60 bpm Sinus node dysfunction (sinus bradycardia, sinus

pause, sick sinus syndrome)

AV node dysfunction (1 st , 2 nd , 3 rd degree AV block) Actively seek and eliminate causes (ICU mediated,

extrinsic)

ICU vagally mediated causes Intubation, suctioning, increased intracranial pressure,

urination, defaecation, vomiting , stretching


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Extrinsic causes Drugs ( antiarrhythmic agents) Electrolytes (K, Mg, Ca)

Hypothyroidism

Hypothermia

Sepsis

Specific infection ( eg. endocarditis) AMI (inferior AMI related AV blocks often transient;

Anterior AMI related AV blocks often irreversible)

Bradyarrhythmia


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Acute treatment

May not need immediate treatment if haemodynamically stableCorrect electrolytes

Treat if Symptomatic sinus bradycardia (hypotension, ischaemia, escape ventricular

arrhythmia)

Ventricular asystole

Symptomatic AV block (2nd degree Type I or 3rd degree with narrow -complexescape rhythm)

Give Atropine: IV 0.6 mg (max 3 mg)

Isoprenaline: Infusion at 0.5 10 mcg/min (caution in ischaemic heart disease)

Pacing: for symptomatic bradycardia .Types including transcutaneous/epicardial/transvenous/permanent


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PACINGIndications for urgent transcutaneous pacing1. Sinus bradycardia with symptoms (SBP


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Indications for temporary transvenous pacing

1. Asystole

2. Symptomatic bradycardia (includes sinus bradycardia withhypotension and Type I 2 nd degree AV block with hypotensionnot responsive to atropine)

3. Mobitz type II 2 nd degree AV block

4. 3rd

degree heart block5. Bilateral BBB (alternating BBB or RBBB with alternating

LAFB/LPFB)6. Newly acquired or age indeterminate bifascicular block (LBBB,

RBBB with LAFB or LPFB) with 1 st degree AV blockMonitor to ensure appropriate pacing and sensing functions and

absence of dislodgment (CXR)Frequent (at least once per 24 hours) testing of pacing thresholds

(pacing energy is usually set at more than 3 times the threshold)


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Pacemakers

Devices that "pace" the heart rate when it istoo slow (bradycardia) can take over for theheart's natural pacemaker, the sinoatrialnode, when it is functioning improperly.Pacemakers monitor and regulate the rhythmof the heart and transmit electrical impulses

to stimulate the heart if it is beating tooslowly.


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Oral Anticoagulant in Atrial Fibrillation

Age less than 60, no heart disease, lone atrial fibrillation treat with aspirin. Age less than 60, heart disease, but really no risk factors treat with aspirin. Age greater than 60, but no risk factors treat with aspirin. Add diabetes and coronary artery disease treat with warfarin to an INR of 2 to

3. Age >75 treat with warfarin to an INR of 2 to 3.

Other high-risk patients (heart failure, EF


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Electronic Devices

By delivering a controlled electric shock tothe heart, defibrillators, or cardioverters"shock" the heart back into a normal heartrhythm

Sometimes the devices are external, such asin an emergency situation. Often, the

electronics are implanted in the patient'schest


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Implanted Cardioverter Defibrillators(ICDs)

ICDs are 99 percent effective in stopping life-threatening arrhythmias and are the mostsuccessful therapy to treat ventricularfibrillation, the major cause of sudden cardiacarrest.

ICDs continuously monitor the heart rhythm,automatically function as pacemakers for heart

rates that are too slow, and deliver life-savingshocks if a dangerously fast heart rhythm isdetected.


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Ventricular tachycardia with an ICD


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Devices for Heart Failure

The U.S. Food and Drug Administration (FDA)recently approved a special type of pacemakerfor certain patients with heart failure.

In Cardiac Resynchronization Therapy, animplanted device paces both the left and rightventricles (lower chambers) of the heart

simultaneously. This resynchronizes muscle contractions and

improves the efficiency of the weakened heart


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Cardiac Ablation

In this procedure, one or more flexible, thintubes (catheters) are guided via x-ray into theblood vessels and directed to the heartmuscle.

A burst of radiofrequency energy destroysvery small areas of tissue that give rise to

abnormal electrical signals


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Catheter Ablation


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Surgery

Although surgery is sometimes used to treatabnormal heart rhythms, it is morecommonly elected to treat other cardiacproblems, such as coronary artery diseaseand heart failure.

Correcting these conditions may reduce the

likelihood of arrhythmias


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Indications for surgical ablation to treat AF

Patients with symptomatic AF undergoing othercardiac surgery

Selected patients with asymptomatic AF

undergoing cardiac surgery in whom ablationcan be performed with minimal risk Stand-alone surgery for AF should be considered

for patients with symptomatic AF who prefer a

surgical approach, have failed one or moreattempts at catheter ablation, or are notcandidates for catheter ablation


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Figure 1 The corridor procedure for AF

Lee, R. et al. (2009) Surgery for atrial fibrillationNat. Rev. Cardiol. doi:10.1038/nrcardio.2009.106


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Figure 2 The surgical maze



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Figure 3 Bipolar radiofrequency ablation using Cardioblate BP2 (Medtronic,Inc., Minneapolis, MN)


Permission obtained from S. Klein, Medtronic, Inc., Minneapolis, MN

arrhythmia overview

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