prehospital care.docx

8/10/2019 Prehospital Care.docx

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Prehospital Care

Care of hemodynamically unstable patients is guided by ACLS protocols, including

direct current (DC) cardioversion.

Symptomatic patients may benefit from intravenous (IV) rate-controlling agents, either

calcium-channel blockers or beta-adrenergic blockers.

Emergency Department Care

Immediate interventionsABCs

Patients placed on cardiac monitor, O2, and ABCs are being assessed, ECG, IV access

Unstable patients require immediate DC cardioversion.8

o Hypotension

o Decompensated CHF

o Ongoing ischemia or infarction

These initial interventions occur simultaneously by the team of physicians and nursestaking care of the patient.

Routine care9,10

In most circumstances, the patient is stable but has an elevated ventricular response andwill require rate-controlling medications, with a heart rate goal of under 80. This

recommended heart rate target was challenged in the RACE II study that examined HR of

110 versus less than 80. The lenient arm had no difference than the strict control arm per

a composite outcome of cardiac death, CHF, stroke, systemic bleeding, and life-threatening arrhythmic events.

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If there is another clinical condition driving the tachycardia, such as fever, infection, ordehydration, then efforts at temperature control and restoration of normovolemia will aidin controlling the tachycardia.

Consideration of anticoagulation based upon patient risk factors may also begin in the

emergency department.

Cardioversion12

Cardioversion can be pharmacologic based or electrical.

Anticoagulation and cardioversion may be indicated. Since there is a risk of thrombus formation

and fragmentation, patients in atrial fibrillation for greater than 48 hours should receivetherapeutic anticoagulation (INR 2-3 range) for 3 weeks prior to cardioversion. Alternatively,

these patients can undergo heparinization, and TEE, and cardioversion if no thrombus is

detected. In each case, anticoagulation needs to be continued for an additional 4 weeks.

Electrical cardioversion13


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DC cardioversion is the treatment of choice in the unstable patient with atrial fibrillation.

Cardioversion is indicated in patients with first time atrial fibrillation or in patients with

paroxysmal atrial fibrillation.

Since atrial fibrillation begets atrial fibrillation, one may delay or prevent permanent

atrial fibrillation by decreasing the overall time spent in atrial fibrillation in these early

clinical stages. There is little utility in cardioverting stable patients with permanent atrial fibrillation, and

the goal in this group is rate control.

Placement of pads or paddle positions include anterior-lateral (ventricular apex and right

infraclavicular) and anterior-posterior (sternum and left scapular), with at least one studysuggesting increased efficacy with the anterior-posterior method.

Biphasic waveforms are proved to convert atrial fibrillation at lower energies and higher

rates than monophasic waveforms.

Strategies include dose escalation (70, 120, 150, 170J for biphasic) or (100, 200, 300,360J for monophasic) versus beginning with single high energy/ highest success rate for

single shock delivered.

Patients who are stable and/or awake and can tolerate sedation should be pretreated, withtypical regimens involving midazolam, fentanyl, and propofol.

Cardioversion of patients with implanted pacemakers and defibrillator devices is safe

when appropriate precautions are taken. Keeping the cardioversion pads in an AP

orientation ensures that the shocks are not directly over the generator. Alteration in pacerprogrammed data has been reported, as well as heart block and elevated enzymes if the

current gets conducted through a pacer lead.

Stunning of the atria and stasis can occur after cardioversion, and this can lead tothrombus formation even though the patient is in sinus rhythm. Therefore, patients would

undergo anticoagulation for several weeks afterwards.

Risks of cardioversion

o Risks with sedation

o Risk of thromboembolism (70 kg) was evaluated. This treatment was successful in terminatingAF in 94% of episodes (mean time to symptom resolution of 133 minutes).

Rate control

In most instances, patients presenting to the ED have preexisting atrial fibrillation and a rapid

ventricular response. These individuals may already be on beta-blockers or calcium channel


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blockers, and initial attempts at rate control should be initiated with same class medications

given intravenously, trying to avoid mixing classes of nodal blocking agents.

Extreme care must be taken in patients with preexcitation syndrome and atrial fibrillation.

Blocking the AV node in some of these patients may lead to AF impulses exclusively

transmitted down the accessory pathway, and this can result inventricular fibrillation.(Ifthis happens, the patient will require immediate defibrillation.) Alternative therapies for

the treatment of arrhythmia in this group include procainamide and amiodarone.

Intravenous diltiazem or metoprolol are commonly used drugs for AF with RVR.

Amiodarone has been used in patients with CHF who may otherwise not tolerate

diltiazem or metoprolol. Digoxin may also be used, but its peak effect may not be for 6

hours.

Antiarrhythmic drugs

Antiarrhythmic drugs that can terminate atrial fibrillation include procainamide, disopyramide,

propafenone, sotalol, flecainide, amiodarone, ibutilide, and dronedarone. The efficacy ofantiarrhythmic drugs has been linked to the duration of atrial fibrillation.

The American College of Cardiology/American Heart Association/European Society of

Cardiology (ACC/AHA/ESC) Guidelines make the following recommendations regarding

pharmacologic conversion of atrial fibrillation (AF):

Conversion of AF less than or equal to 7 days15

o Agents with proven efficacy include dofetilide, flecainide, ibutilide, propafenone,

and to a lesser degree, amiodarone and quinidine.

o Less effective or incompletely studied agents in this scenario include

procainamide, digoxin, and sotalol. Conversion of AF lasting greater than 7 days

o Agents with proven efficacy include dofetilide, amiodarone, ibutilide, flecainide,

propafenone, and quinidine.

o Less effective or incompletely studied agents in this scenario includeprocainamide, sotalol, and digoxin.

Conversion of AF lasting greater 90 days - Oral propafenone, amiodarone, and dofetilide

have been shown to be effective at converting chronic AF to normal sinus rhythm (NSR).

The US Food and Drug Administration (FDA) mandates inpatient monitoring for dofetilide

initiation. Patients who start sotalol usually require inpatient monitoring (fortorsade de pointes),

although patients with no heart disease, QT interval


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Anticoagulation

ACC/AHA/ESC 2006 Guidelines for Antithrombotic Therapy in Patients with AF5,9,17

Opentable in new window

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Table

High risk factor Moderate risk factor Low risk

Prior CVA/TIA Age >75 Age 65-74

Mechanical heart valve HTN Female gender

Mitral stenosis CHF CAD

EF 75 Age 65-74

Mechanical heart valve HTN Female gender

Mitral stenosis CHF CAD

EF


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Some people may be treated by their GP, whereas others may be referred to a cardiologist (heart

specialist).

The first step is to try to find out the cause of the atrial fibrillation. If a cause is found, you may

just need treatment for this.

For example, medication to correct hyperthyroidism (an overactive thyroid gland) may cure

atrial fibrillation.

If no underlying cause can be found, the treatment options are:

medicines to control atrial fibrillation,

medicines to reduce the risk of stroke,

cardioversion (electric shock treatment),

ablation, or

having a pacemaker fitted.

Medicines to control atrial fibrillation

Medicines called anti-arrhythmics can control atrial fibrillation by:

restoring a normal heart rhythm, and/or

controlling the rate at which the heart beats.

The choice of anti-arrhythmic medicine depends on the type of atrial fibrillation, any othermedical conditions, side effects of the medicine chosen and how well the atrial fibrillation

responds.

Some people with atrial fibrillation may need more than one anti-arrhythmic medicine to control

it.

Restoring a normal heart rhythm

A variety of drugs are available to restore normal heart rhythm. These include:

flecainide (and other similar drugs),

beta-blockers (particularly sotalol), and

amiodarone.

New drugs are in development that may restore normal heart rhythm, but they are not widelyavailable yet. If a particular drug does not work or the side effects are troublesome, another may

be tried.


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Controlling the rate of the heartbeat

The aim is to reduce the resting heart rate to under 90 beats a minute, although in some peoplethe target is under 110 beats a minute.

A beta-blocker (such as bisoprolol or atenolol) or a calcium channel blocker (such as verapamilor diltiazem) will be prescribed.

A medicine called digoxin may be added to help further control the heart rate. In some cases,

amiodarone may be tried.

Side effects

As with any medicine, anti-arrhythmics can cause side effects. Read the patient informationleaflet that comes with the medicine for more details.

The most common side effects of anti-arrhythmics are:

Beta-blockers: tiredness, coldness of hands and feet, low blood pressure, nightmares and

impotence.

Flecainide: nausea, vomiting and heart rhythm disorders.

Amiodarone: sensitivity to sunlight (high-protection sunscreen must be worn or skin covered

up), lung problems, changes to liver function or thyroid function (regular blood tests can check

for this) and deposits in the eye (these go away when treatment is stopped).

Verapamil: constipation, low blood pressure, ankle swelling and heart failure.

Medicines to reduce the risk of stroke

The way the heart beats in atrial fibrillation means that there is a risk of blood clots forming in

the heart chambers. If these get into the bloodstream, they can cause a stroke (see

Complications).

Your doctor will assess your risk to minimise your chance of a stroke. They will consider your

age and whether you have a history of any of the following:

stroke or blood clots,

heart valve problems,

heart failure,

high blood pressure,

diabetes, or

heart disease.

You will be classed as having a high, moderate or low risk of stroke and will be given

medication according to your risk.

Depending on your level of risk, you may be prescribed warfarin or aspirin.
http://www.nhs.uk/Conditions/Atrial-fibrillation/Pages/Complications.aspxhttp://www.nhs.uk/Conditions/Atrial-fibrillation/Pages/Complications.aspxhttp://www.nhs.uk/Conditions/Atrial-fibrillation/Pages/Complications.aspx


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Warfarin

People with atrial fibrillation who have a high or moderate risk of stroke are usually prescribedwarfarin,unless there is a reason they cannot take it.

Warfarin is an anticoagulant, which means it stops the blood from clotting. There is an increasedrisk of bleeding in people who take warfarin, but this small risk is usually outweighed by the

benefits of preventing a stroke.

It is very important to take warfarin as directed by the doctor. People on warfarin need to have

regular blood tests and, following these, their dose may be changed.

Lots of medicines can interact with warfarin and cause serious problems, so check that any new

medicines are safe to take with warfarin.

Drinking more than moderate amounts of alcohol or drinking cranberry juice can also affect your

warfarin and is not recommended.

Aspirin

People with atrial fibrillation who have a low risk of stroke are likely to be given alow dose of

aspirinto take every day instead of warfarin.

People who are unable to take warfarin may also be given aspirin instead.

Cardioversion

Cardioversion may be tried in some people with atrial fibrillation. The heart is given a controlledelectric shock to try to restore a normal rhythm.

The procedure normally takes place in hospital, where the heart is carefully monitored.

In people who have had atrial fibrillation for more than two days, cardioversion is associated

with an increased risk of clot formation. If this is the case, warfarin is given for three to four

weeks before cardioversion and for at least four weeks afterwards to minimise the chance ofhaving a stroke.

If the cardioversion is successful, warfarin may be stopped. However, some people may need to

continue with warfarin after cardioversion if there is a high chance of their atrial fibrillationreturning and they have a moderate to high risk of stroke (see above).

Catheter ablation

Catheter ablation is a procedure that very carefully destroys the diseased area of your heart andinterrupts abnormal electrical circuits. It is an option if medication has not been effective or

tolerated.
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Catheters (thin, soft wires) are guided through one of your veins into your heart, where they

record electrical activity. When the source of the abnormality is found, an energy source (such as

high-frequency radiowaves that generate heat) is transmitted through one of the catheters todestroy the tissue.

This can be quite a long procedure and commonly takes two to three hours, so it may be doneunder general anaesthetic (where you are put to sleep).

For more detailed information on catheter ablation for atrial fibrillation, go to theArrhythmiaAlliancewebsite

Having a pacemaker fitted

A pacemaker is a small, battery-operated device that is implanted in your chest (just below your

collarbone). It is usually used to prevent your heart rate going too slowly, but in atrial

fibrillation, it may help your heart beat regularly.

Having a pacemaker fitted is usually a minor surgical procedure performed under a localanaesthetic (the area is numbed).

This treatment may be used when medicines are not effective or are unsuitable.

For more information, go toHealth A-Z: pacemaker implantation.
http://www.heartrhythmcharity.org.uk/http://www.heartrhythmcharity.org.uk/http://www.heartrhythmcharity.org.uk/http://www.heartrhythmcharity.org.uk/http://www.nhs.uk/conditions/PacemakerImplantation/Pages/Introduction.aspxhttp://www.nhs.uk/conditions/PacemakerImplantation/Pages/Introduction.aspxhttp://www.nhs.uk/conditions/PacemakerImplantation/Pages/Introduction.aspxhttp://www.nhs.uk/conditions/PacemakerImplantation/Pages/Introduction.aspxhttp://www.heartrhythmcharity.org.uk/http://www.heartrhythmcharity.org.uk/

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