alaska nurse practitioner annual conference...

Alaska Nurse Practitioner Annual Conference 2009

LAURIE RACENET, RN, MSN, ANP,

CEPS, CCDS

Alaska Heart Institute

Member: Boston Scientific Allied Professional Advisory

Board

Participant in Industry Sponsored Research: Boston

Scientific, Medtronic and St. Jude Medical

Speaker for Boston Scientific Corporation and

Medtronic, Inc

No pharmaceutical relationships to disclose

Action Potential

Movement of Potassium, Sodium and Calcaim ions across the cell membranes of the myocardium

Anti-arrhythmic medications work on these ion channels

Automaticity

Re-entry

Triggered Activity

Caused by an abnormal acceleration of phase 4

These arrhythmias often warm up and slow down gradually

Often, an underlying metabolic cause can be determined

Think of this as an “itch”, that anti-arrhythmic drugs can sometimes help sooth

Examples Multifocal atrial tachycardia

VT in the acute MI (ischemia)

Common metabolic causes of automatic arrhytmias Cardiac ischemia

Hypoxemia

Hypokalemia

Hypomagnesemia

Acid-base disturbance

High sympathetic tone

Use of sympathomimetic agents

Most clinically significant arrhythmias are re-entry arrhythmias

3 things that must be present for re-entry to occur 2 parallel pathways that are connected proximately and distally 1 pathway must have a longer refractory period than the other The pathway with the shorter refractory period must conduct

electrical impulses more slowly than the other

If all these are present, a properly timed premature impulse can set off the arrhythmia circuit

Examples of re-entry arrhythmias WPW AVNRT VT in patients with scar from previous MI

Resembles automaticity in that new action potentials are created by a “leakage” of positive ions into the cell

Similar to re-entry in that it is not always spontaneous and can be triggered by properly timed premature beats

Cannot be overdrive paced

Examples: Dig toxic arrhythmias

Torsades de Pointes (think patients with Long QT)

Classes are based on their effect on the action potential

Classed as I –IV

Easiest to remember and study by class than individually

Class I (A, B and C)- sodium channel blockers

Class II – beta blockers

Class III – potassium channel blockers

Class IV – calcium channel blockers

Miscellaneous – digoxin, adenosine, magnesium

Dronedarone (Multaq) just released Aug 2009

Quinidine

Procainamide

Disopyramide (Norpace)

Prolong the QRS (Phase 0, slows the influx of sodium ions into the cell) and the QT intervals

Action Potential of

Class 1A drugs

Dosages for Class IA Drugs

Quinidine Sulfate

300 – 600mg every 6 hours

Quinidine Gluconate

324 – 972mg every 6 – 8 hours

Procainamide


Disopyramide


Nausea and diarrhea

Constipation

Heart block

Decreased appetite

Widened QRS

Prolonged QT interval

Ventricular arrhythmias

Complete AV block

Congential Long QT Syndrome

Dig toxicity

Lidocaine

Mexiletine

Phenytoin

Does not change the QRS, but shortens the QT interval

Action Potential of

Class 1B drugs

Dosages for Class IB Drugs

Lidocaine

per ACLS Protocol

Mexiletine


Phenytoin

300 – 500mg per day in divided doses

Tingling sensations

Visual changes

Slurred speech

Headache

Decreased appetite, GI upset

Confusion and mental changes


2nd of 3rd degree block

Use caution in patients with epilepsy or heart failure

Flecainide

Propafenone

Prolongs the QRS, but not the QT interval

Action Potential of

Class 1C drugs

Dosages for Class IC Drugs

Flecainide


Propafenone


Tingling sensations

Slurred speech

Blurred vision

Decreased appetite, GI upsets

Headache

Bradycardia

Widened QRS


Known coronary artery disease

2nd or 3rd degree heart block

Bifasicular block

Profanenone has some beta blocker activity

These drugs can organize atrial fib into atrial flutter. May want to add a small dose of beta blocker just in case.

Little effect on the Action Potential – effect is primarily on sinus node and secondarily on the AV node

Use bisoprolol (Zebeta), acebutelol (Sectral), pindolol for younger patients (less sleepiness, fatigue associated with these drugs)

If using for rate/arrhythmia control, it is OK to use generic and cheap.

When using for heart failure metoprolol succinate (not tartarate) Carvedilol (for patients with financial concerns, use generic

carvedilol with BID dosing instead of once a day Coreg CR) bisoprolol

Fatigue

Sleepiness

Bradycardia

Underlying bradycardias or advanced heart block

Use caution with diabetes

Use caution in patients with reactive airway disease

In heart failure patients, it may be best to diurese them before starting beta blocker

Tikosyn

Sotalol

Ibutalide

Bretyllium

Amiodarone

Prolongs the QT interval = risk for torsades

Action Potential of

Class III drugs

Dosages for Class III Drugs

Tikosyn

500mg every 12 hours

250mg every 12 hours for impaired renal function

Sotalol


Amiodarone

800 – 1600mg per day for 3 – 10 days, the 100 – 400mg per day

CLASS III DRUG CALCULATOR

9/2/2009 Age Wt, Lbs Creatinine

Enter data in yellow boxes:

Estimated Creatinine Clearance:

Male: #DIV/0! ml/min

Female: #DIV/0! ml/min

If Creatinine Clearance is: Tikosyn dose: Sotalol dose:

>60 500 bid 80-160 Q12

40-60 250 bid switch to Q24

20-40 125 bid stop drug

<20 stop drug stop drug

Most recent QTc interval: msec

QT limits during maintenance: Tikosyn Sotalol

-narrow QRS 500 520

-wide QRS (>100ms) 550 JT interval 330

May refill prescription:

____________________________, MD Laurie Racenet ANP

9/2/2009

Do not refill:______________________________________, MD

9/2/2009

Prolonged QT interval Ventricular arrhythmias, including torsades Amiodarone

Blue skin, pulmonary hypertension, liver dysfunction, hyper or hypothyroid, blindness

Also be aware of effect on heart rate. Will cause bradycardia

Be very cautious of interaction between amiodarone and Coumadin – cut Coumadin dose in half when starting amiodarone

Recently there has been evidence of an interaction between amiodarone and simvastatin at doses of 40mg and higher. Change to different cholesterol treatment when starting amiodarone

Long QT Syndromes

Tikosyn should not be given if a QTc has ever been greater than 440ms

Severe renal impairment

Uncontrolled CHF (sotalol only)

Cardiazem

Verapamil

Beware of calcuim channel blockers in systolic heart failure, but they may have some benefit in diastolic heart failure

Good rate controlling drugs

Very helpful in atrial fib

Use generic formulations

These are also anti-anginal drugs and may be a good choice if the patient has rapid heart rates and CAD with stable angina

Fatigue

Ankle Swelling (cardiazem)

Constipation

Worsening heart failure

Daytime sleepiness

Bradycardias

Severe LV dysfunction

2nd or 3rd degree heart block

Atrial fib with a known accessory pathway, such as WPW (verapamil)

Severe hypotension

Acute MI

Unclassified Anti-Arrhythmic Agents

Digoxin

Adenosine

Magnesium

Digoxin

Increases intracellular contraction

Increases parasympathetic tone

Use lower dose in elderly

Monitor for subtle signs of toxicity

Adenosine

In high concentrations has a dramatic, but short depressive effect on the SA and AV nodes

Produces high grade AV block 10 – 30 seconds after IV administration

Can terminate re-entrant arrhythmias and is useful in diagnosing atrial flutter and fib

Magnesium

Precise mechanism is not established

Most useful in treating TDP

Dromadarone (Multaq)

“Cousin” to Amiodarone

Approved for atiral fib

Has properties belonging to all 4 Vaughan-Williams Classes

Just approved for use August 2009

Dronedarone

Dosage: 400mg twice a day with the morning and evening meals

Most common side effects:

nausea, diarrhea, abdominal pain, vomiting and asthenia

Contraindications: Class IV heart failure or Class II – III heart failure with a recent decompensation requiring hospitalization or referral to a specialized heart failure clinic

Other Precautions

•Pregnancy – woman of child bearing age should use effective contraception while on drug

•Stop if QTc greater or equal to 500ms

•Maintain normal serum levels of potassium and magnesium

Drug Interactions

Simvastatin

Any drug that can prolong the QT interval is contraindicated

Calcium channel blockers

Beta blockers

Digoxin

Atrial flutter Membrane Active AADs are not a 1st line choice – ablation

has fewer side effects and is considered curative if successful (95%)

May choose to use beta blockers, calcium channel blockers or dig to slow the heart rate

Supraventricular arrhythmias Membrane active AADs are usually not indicated Consider patient circumstances – may not be 1st line

treatment

Ventricular arrhythmias Be aware that membrane active AADs do not have a

mortality advantage If EF < 35%, patient should be considered for ICD

Atrial fib

Rate control vs rhythm control

Heart failure

HRS and ACC recommend patient fail one membrane active AAD before being considered for curative ablation

Get a base line QTc (if QTc has EVER been greater than 440ms do not use Tikosyn)

Consider whether another treatment might have a stronger indication

Be sure you have ruled out treatable causes of arrhythmias

Consider Co-morbidities: Do not use class IC drugs in patients with CAD Use caution with beta blockers in patients with

diabetes or asthma Do not use calcium channel blockers in patients with

heart failure (systolic dysfunction)

Hospital admission for 3 days Serial EKGs and bloodwork QRS widening QTc prolongation BMP –watch creatinine clearance Flecainide levels Liver and thyroid function with amiodarone Baseline and yearly PFTs with amiodarone Baseline and yearly vision exam with amiodarone

EKG and blood work every 3 months Only give 3 months supply of the drug at a time Consent prior to giving drugs (?) If patients experience ventricular arrhythmias, consult EP –

the drug may need to be stopped

Be aware of potential side effects Amiodarone is a wonderfully effective drug for both

ventricular and supra-ventricular arrhythmias, BUT, it has ugly and potentially permanent side effects. Consider stopping the drug for any of the following reasons:

Unexplained SOB Vision changes Change in liver function test Symptoms of thyroid disorder Breakthrough arrhythmia requiring cardioversion

Monitor arrhythmia burden: if there is a lot of break-through arrhythmia, may need to consider the drug a failure

Bottom line:

Class I and Class III AADs are serious business. It is best to consult EP prior to initiating these meds 561-3211 – ask to speak to EP on call

Class II and Class IV drugs have a better safety profile and can be safely used to treat most arrhythmias. May want EP consult to determine if the patient is a candidate for curative ablation.

Safe monitoring of AADs can be done very effectively by NPs

Questions?

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