Download Ch. 20-Drugs Used to Treat Dysrhythmias

Chapter 20
Drugs Used to Treat
Dysrhythmias
•the
heart pumps blood to itself through coronary arteries
and to the rest of the body’s tissues
•there
are 2 phases of heart action:
•diastole: resting phase, heart chambers fill with blood, heart
is relaxed in this phase
•systole: working phase, heart contracts, blood is pumped
through the vessels when the heart contracts
•systole
and diastole make up the cardiac cycle
•the conduction system (electrical system) controls the cardiac
cycle
•heart muscle must relax and fill with blood and contract to
pump blood, in a coordinated fashion. Otherwise cells
do not get enough blood and oxygen
•to
coordinate the cardiac cycle the heart’s muscle fibers
are linked together
•an electrical impulse starts in wall of right atrium, it’s
conducted to muscles fibers in right and left atria, causing
the atria to contract. Then the impulse moves to the
ventricles, and causes them to contract
•for every heartbeat an electrical impulse is conducted
through the heart
4 structures in the heart wall make up the conduction
system (see fig. 20-1 pg. 256):
•sino-atrial node (SA node)
•atrio-ventricular node (AV node)
•atrio-ventricular bundle (AV bundle aka bundle of His)
•purkinje fibers
•SA
node: starts the impulse in the right atrium, its also called the
pace-maker. It sets the beat of the heart
•the electrical impulse travels from the SA node to the right and left
atria
•the right and left atria contract as the impulse travels through them.
Blood pumps to ventricles
•electrical impulse reaches AV node, it is at the bottom of the right
atrium near the right ventricle
•the impulse travels through the AV node to the AV bundle, aka
bundle of His, in the wall separating the right and left
ventricles
•AV bundle has right and left branches, they extend to all parts of the
ventricular wall
•the right bundle branch conducts the impulse to the right ventricle
•left bundle branch conducts the impulse to the left ventricle
•Purkinje fibers branch into the myocardium from the right and left
bundle branches
•when impulse reaches the ventricular muscle, the ventricles contract
•after contracting the ventricles relax
•arrhythmia:
without rhythm
•dysrhythmia: an abnormal rhythm
•there
is a disturbance in the normal electrical conduction
causing:
•an abnormal heart muscle contraction
•an abnormal heart rate
•areas
outside the SA node can act as a pacemaker, this causes
an irregular heart beat
•some rhythms are life-threatening
•blocks can occur in the conduction system, block prevents
impulse from traveling in a normal manner, can be lifethreatening
•electrocardiograms
(ECGs): record the electrical activity
of the conduction system
•this is recorded in waves
•waves give the cardiac cycle a distinct appearance
•each wave represents electrical activity in a certain part
of the heart
•the P wave, QRS complex, and T wave are the major parts
of cardiac cycle
•if a problem occurs in a part of the conduction system,
the wave for that part appears abnormal
•by studying ECG doctor determines the site of problem
in the conduction system or the area of heart
muscle damage
•see
fig. 20-2 pg. 257
Types of Dysrhythmias:
•normal
sinus rhythm impulses start in SA node
•the heart rate is between 60-100 beats per minute
•various heart disease cause changes in conduction system
•dysrhythmias are classified by origins within the heart tissues
Supraventricular dysthythmias: these develop above
the bundle of His:
•Sinus
tachycardia: heart rate is rapid, Impulses start in SA node
(fig 20-4 p. 258)
•Sinus
bradycardia: heart rate is slow, impulses start in SA node
(fig 20-5)
•Premature atrial contraction (PAC): SA node sends out impulse early
(fig 20-6)
•Paroxysmal atrial tachycardia (PAT): normal rhythm that suddenly
turns into tachycardia. Bursts(paroxysms) of tachycardia
occur. The tachycardia stops suddenly. (fig 20-7)
supraventricular dysrhythmias cont…
•atrial
flutter:
impulses start in the atria at a rapid rate
-ventricles do NOT respond to every impulse (fig 20-8),
-more P waves than QRS complexes
-QRS complexes occur at regular impulses
-persons pulse is regular
•atrial
fibrillation: impulses start in atria at multiple sites
-no P waves
-Impulses are conducted to the ventricles at irregular intervals (fig 20-9)
-pulse is irregular.
-Atria quiver, not contract
-Blood not pumped from atria to ventricles in normal amounts, thus
inadequate blood pumped to rest of body
•junctional
rhythms: impulses start in the AV node, there are no P waves (fig
20-10), these can occur at normal or slow rates
blocks in conduction pathways:
-described by degree of the block:
•first-degree heart block:
-impulse takes longer to travel from SA node to AV note
-PR interval is longer than normal (fig 20-11)
-rhythm is regular
•second-degree
heart block:
-some impulses from SA node do not reach ventricles
-Impulses from SA node take longer and longer to travel through the AV
node until a beat is skipped
-QRS complex does NOT follow a P wave (fig 20-12)
-rhythm is irregular
•third-degree heart block:
-impulse is blocked between the atria and ventricles (fig 20-13)
-Impulse cannot reach the ventricles
-ventricles must create their own impulses
-P waves appear but are not related to QRS complexes
-QRS complexes are wider than normal
-Heart rate is very slow
-LIFE THREATENING DYSRHYTHMIA!!!
Ventricular dysrhythmias: these develop below
the bundle of His:
•Premature
ventricular contraction (PVC):
-impulse created in ventricles
-occurs earlier than the next regular beat
-QRS complex is wide and bizarre (fig 20-14)
-unifocal PVCs come from one site, all look the same
-multifocal PVCs created in many sites (fig. 20-15)
-bigeminy: every second complex is a PVC (fig 20-16)
-trigeminy: every third complex is a PVC
-two PVCs can occur in a row (fig 20-17)
-they can be unifocal or multifocal, called coupled PVCs
-a run of ventricular tachycardia is several PVCs in a row (fig
20-18) rhythm returns to normal
-PVCs can mean heart muscle is irritable
-LIFE THREATENING!!!
Ventricular dysrhythmias cont….
Ventricular tachycardia (VT):
-impulses start in ventricles
-heart rate can change from 40-250 beats per minute
-QRS complexes are wide and bizarre
-rhythm looks like a series of PVCs (fig 20-19)
-LIFE THREATENING!!!
-if not corrected it progresses to ventricular fibrillation
Ventricular fibrillation (VF or V fib):
-impulses start from multiple sites in ventricles
-P waves and QRS complexes are not present (fig 20-20)
-ventricles quiver, not contract
-DEADLY!!! person is in cardiac arrest
Asystole:
-means no contraction
-no electrical action occurs in heart (fig 20-21)
-DEADLY!!! person in cardiac arrest
•conduction
system tissues are affected by calcium and
sodium
•ion is atom with electrical charge
•atom
is smallest part of an element
•element
is a simple substance that cannot be broken
down into another substance
•calcium
and sodium are elements:
-calcium: SA and AV nodes depend on calcium ions for
electrical conduction
-sodium: atrial muscle, His-Purkinje system, and
ventricular muscle depend on sodium for
contraction
Drug Therapy for Dysrhythmias:
•Anti-dysrhythmic
agents are drugs used to prevent or
correct abnormal heart rhythms
•depending on drug, anti-dysrhythmic agents affect the
heart’s conduction system by:
-inhibiting sodium ion movement, this depresses the
heart muscle
-prolonging or shortening the duration of electrical
stimulation on the cells
-increasing or decreasing the time between
electrical impulses
-slowing the conduction rate between the atria and
ventricles
Delegation Guidelines
Drug Therapy for Dysrhythmias:
Some drugs used to treat dysrhythmias are given
parenterally- by intramuscular or intravenous injection.
Because you do NOT give parenteral dose forms, they are
not included in this chapter. Should a nurse delegate the
administration of such to you, you must:
- remember that parenteral dosages are often very
different from dosages other routes
-Refuse the delegation. Make sure to explain why.
Do NOT just ignore the request. Make sure
the nurse knows that you cannot give drug
and why
Drug therapy for Dysrhythmias
amiodarone hydrochloride (Cordarone):
-slows the rate of electrical conduction, increases the time
between contractions
-drug is given to convert the following dysrhythmias to
normal sinus rhythm:
- supraventricular tachycardias – rapid arrhythmias
that occur above the bundle of His
- atrial fibrillation
- atrial flutter
- bradycardia-tachycardia syndromes
- ventricular tachycardia
- ventricular fibrillation
Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
amiodarone hydrochloride (Cordarone):
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema, fainting, palpitations
(person says “heart skips beats” or “my heart is racing”), measure BP, apical pulse (for 1
min), and respirations
PLANNING: oral dose forms are: 100, 200, 400mg tablets
IMPLEMENTATION: initial adult dose is 800-1600mg daily in divided doses for 1-3
weeks. Then a dosage of 600-800mg is given for about 1 month, lowest effective dose
should be used (usually 400mg)
EVALUATION: report and record:
-fatigue, tremors, involuntary muscle movements, sleep problems, numbness and tingling,
coordination problems, dizziness, confusion. Many of these resolve when dose
is reduced or drug is discontinued, provide for safety
-dyspnea on exertion, non-productive cough, chest pain with breathing: symptoms resolve
when drug is discontinued
-blurred vision, narrowed peripheral vision, halos: provide for safety, resolve when drug is
discontinued
- nausea, vomiting, constipation, abdominal pain, anorexia: common with high
dosages, resolve with lower dosages or divided doses
-dysrhythmias: drug may cause dysrhythmias or cause existing ones to worsen
-skin reactions: rash, burning, tingling, redness, blistering: from exposure to sun (photosensitivity). person should wear sunscreen, long sleeved shirts, avoid exposure
to sun
-anorexia, nausea, vomiting, jaundice: may signal liver toxicity
Drug therapy for Dysrhythmias cont…
-Beta blockers are widely used as anti-dysrhythmic
agents (ch.14)
-by blocking beta receptors, they block the heart’s
response to sympathetic nerve stimulation
-heart rate, BP and cardiac output are reduced
-see table 14-2 for beta blockers used to treat
dysrhythmias
-they are effective in converting the following
dysrhythmias to normal sinus rhythm:
•various ventricular dysrhythmias
•sinus tachycardia
•paroxysmal supraventricular tachycardia
•premature ventricular contractions
•atrial flutter when tachycardia is present
•atrial fibrillation when tachycardia is present
Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
for beta blockers:
See chapter 14
Drug Therapy for Dysrhythmias cont…
Disopyramide (Norpace):
-Prolongs
the simulation on the cells and increases the time
between electrical impulses
-Effective
in converting the following dysrhythmias to normal
sinus rhythm:
-atrial fibrillation
-paroxysmal supraventricular tachycardia
-runs of ventricular tachycardia
-ventricular tachycardia
Drug therapy for Dysrhythmias
Assisting With the Nursing Process
disopyramide (Norpace):
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema, fainting,
palpitations (person says “heart skips beats” or “my heart is racing”),
measure BP, apical pulse (1 min) and respirations, ask about bowel
elimination and urination
PLANNING: oral dose form: 100, 150mg tablets
100, 150mg extended release capsules
IMPLEMENTATION: dosage depends on person needs, usually 400800mg/day, usually 150mg every 6 hours
EVALUATION: report and record:
- dry mouth, nose and throat: provide oral hygiene, give, hard candy or ice
chips if care plan allows
-bradycardia, signs of heart failure(ch. 21): signs of myocardial toxicity
-difficulty starting a urine stream: run tap water or immerse hand in
water, measure input/output
-constipation, abdominal distention, flatus: ask about bowel elimination and
expelling gas
Drug therapy for Dysrhythmias cont…
flecainide acetate (Tambocor):
-slows
conduction rate through atria and ventricles
-effective
in converting the following dysrhythmias to normal
sinus rhythm:
-ventricular tachycardia
-paroxysmal supraventricular tachycardia
-premature ventricular contractions
Drug therapy for Dysrhythmias
Assisting With the Nursing Process
flecainide acetate (tambocor):
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema,
fainting, palpitations (person says “heart skips beats” or “my heart is racing”),
measure BP, apical pulse (1 min) and respirations, observe for signs and
symptoms of heart failure (ch.21)
PLANNING: oral dose forms: 50, 100, 150 mg tablets
IMPLEMENTATION: initial dose is 100mg every 12 hours, increased
by 50mg twice a day every 4 days. Usual dose is 150mg 2x/day,
max daily dose is 400mg
EVALUATION: report and record:
-dizziness, headache, constipation, nausea: mild, tend
-vision
to resolve
disturbances: provide for safety
-signs and symptoms of heart failure (ch 21), may cause heart failure or
existing heart failure to worsen
-dysrhythmias: may cause or worsen dysrhytmias
Drug therapy for Dysrhythmias cont…
mexiletine (Mexitil):
•shortens
the duration of electrical stimulation on the cells
•increases
the time between electrical impulses
•effective
in converting the following dysrhythmias to normal
sinus rhythm:
•ventricular tachycardia
•premature ventricular contractions
Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
mexiletine (Mexitil):
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema, fainting,
palpitations (person says “heart skips beats” or “my heart is racing”), measure BP,
apical pulse (1 min) and respirations, ask about GI symptoms, observe orientation to
person, time and place. Observe for agitation
PLANNING: oral dose forms: 150, 200, 250mg tablets
IMPLEMENTATION: usual dose is 200-400mg every 8 hours, give
drug with food or antacids, if ordered
EVALUATION: report and record:
-nausea, vomiting, indigestion: occur
-dysrhythmias: may
-fine
usually with higher doses
cause them or worsen existing ones
hand tremors, coordination problems, light-headedness, blurred vision,
double vision, involuntary eye movement, difficult speech, confusion,
numbness and tingling, drowsiness, seizures: signal toxic effect on CNS
-confusion: observe
for confusion and persons orientation to person, time and
place, provide for safety
Drug therapy for Dysrhythmias cont…
moricizine (Ethmozine):
•slows
the conduction rate between atria and
ventricles
•effective in converting ventricular dysrhythmias to
normal sinus rhythm
•it can cause other dysrhythmias, it is used when
benefits are greater than the risk
Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
moricizine (Ethmozine):
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema,
fainting, palpitations (person says “heart skips beats” or “my heart is
racing”), measure BP, apical pulse (1 min) and respirations, ask about
GI symptoms, observe orientation to person, time and place.
Observe for agitation and confusion
PLANNING: oral dose forms: 200, 250, 300mg tablets
IMPLEMENTATION: initial dose is 200mg every 8 hours, may be
increased by 150mg every 3 days. usual dosage is between 600900mg/day, given in divided doses around the clock, give drug with
food and milk
EVALUATION: report and record:
-hypotension, dizziness: may occur with starting drug, usually subside,
provide for safety
-nausea: give drug with food or milk
-dysrhythmias: may cause them or worsen existing
-euphoria, confusion: observe orientation to person time and place,
provide for safety
Drug therapy for Dysrhythmias cont…
procainamide hydrochloride (Procanbid):



prolongs the duration of electrical stimulation on the cells
increases the time between electrical impulses
effective in converting the following dysrhythmias to normal
sinus rhythm:
◦
◦
◦
◦
ventricular dysrhythmias
supraventricular dysrhythmias
atrial flutter
atrial fibrillation
Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
procainamide hydrochloride (Procanbid):
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema,
fainting, palpitations (person says “heart skips beats” or “my heart
is racing”), measure BP, apical pulse (1 min) and respirations
PLANNING: oral dose forms: 250, 375, 500mg capsules/tablet
and 250, 500, 750, 1000mg sustained-release tablets
IMPLEMENTATION: initial dose is 1-1.25g, followed with 750mg
one hour later if arrhythmia is still present, dosage is maintained at
0.5-1g every 4-6 hours (some every 3-4), given in divided doses
around the clock, give with food or milk
EVALUATION: report and record:
-drowsiness, sedation, dizziness, hypotension: provide for safety
- fever, chills, joint and muscle pain, skin eruptions: may signal changes
in white blood cells
Drug therapy for Dysrhythmias cont…
propafenone (Rythmol):
slows the conduction rate between the atria and
ventricles
 effective in converting atrial fibrillation and
ventricular dysrhythmias to normal sinus rhythm
 it can cause other dysrhythmias so it is used when
benefits are greater than risks

Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
propafenone (Rhythmol):
ASSESSMENT: observe for dyspnea, chest pain, fatigue,
edema, fainting, palpitations (person says “heart skips beats”
or “my heart is racing”), measure BP, apical pulse (1 min) and
respirations, ask about GI symptoms
PLANNING: oral dose forms: 150, 225, 300mg tablets
and 225, 325 and 425 extended-release tablets
IMPLEMENTATION: initial dose is 150mg every 8 hours,
every 3-4 days dosage may be increased to 225mg every 8
hours, then 300mg every 8 hours (900mg daily), drug is given
around the clock, ask nurse what to do if a dose is missed
EVALUATION: report and record:
- dizziness: provide for safety
- nausea, vomiting, constipation: give drug with food or milk
- dysrhythmias: drug may cause them or worsen existing
Drug therapy for Dysrhythmias cont…
quinidine:
 shortens the duration of electrical stimulation on
the cells
 increases the time between electrical impulses
 slows the heart rate and changes a rapid, irregular
pulse to a slow, regular pulse
 it is effective in converting the following
dysrhythmias to normal sinus rhythm:
◦
◦
◦
◦
atrial flutter
atrial fibrillation
paroxysmal supraventricular tachycardia
premature ventricular contractions
Drug therapy for Dysrhythmias cont…
Assisting With the Nursing Process
quinidine:
ASSESSMENT: observe for dyspnea, chest pain, fatigue, edema, fainting,
palpitations (person says “heart skips beats” or “my heart is racing”),
measure BP, apical pulse (1 min) and respirations, ask about bowel
elimination
PLANNING: oral dose forms for quinidine sulfate: 200, 300mg tablets and
300mg sustained-release tablets
quinidine gluconate: 324mg sustained-release tablets
IMPLEMENTATION: quinidine sulfate: 200-400mg orally 3-5x/day, max
single dose is 600-800mg, give with food/milk
quinidine gluconate: 324-972mg every 8-12 hours
EVALUATION: report and record:
- diarrhea: common with start of drug, usually subsides
- dizziness, faintness: usually subside, provide for safety
- hearing loss, headache, tinnitus, increasing mental confusion, rash, chills,
fever: result from excess quinidine
- hypotension: may occur if person is also on diuretics or anti-hypertensive
meds, provide for safety