Drugs for Cardiac
Disorders
Dr. Kathy Ham
Disorders Requiring
Drugs
• Heart Failure
• Dysrhythmias
• Pain
Drugs for Heart Failure
• Heart failure- when the heart cannot pump enough
blood to meet tissue oxygen and nutrient demands
• Heart is distended, becomes hypertrophied,
sodium and water are retained, causing
decreased renal blood flow
• A combination of drugs are used- the primary ones
are designed to increase cardiac output and get rid
of excess fluid
• 3 pronged attack- increase cardiac output,
vasodilate, and increase fluid output
Drugs
• Inotropic Agents- cardiac glycosides
• digoxin (Lanoxin)
• Phosphodiesterase Inhibitors-
• inamrinone (Inocor)
• milrinone (Primacor)
• Diuretics and ACE inhibitors may
also be used
Digoxin
• Also called a cardiac glycoside
• Comes in PO or IV form
• MOA- exerts a cardiotonic or positive
inotropic effect- improves pumping
ability; also has negative
chronotropic and dromotropic
effects- slows the heart rate and
rate of electrical conduction
• Works best when patient achieves a
steady state tissue concentration-
check therapeutic level frequently
Digoxin
• Indications
• Heart failure
• Atrial fibrillation
• Atrial flutter
• Contraindications
• Severe myocarditis
• Heart blocks
• Electrolyte imbalances
• Renal failure
Digitalization
• Start on loading dose and decrease to maintenance
dose
• May be done slowly (PO) or rapidly (IV)
• Digoxin level- 0.8 to 2 ng/ml therapeutic range
• Digoxin toxicity- treated with Digibind- symptoms:
• Changes in heart rhythm or rate
• Nausea, vomiting
• Visual problems
• Headaches
• Anorexia
• Disorientation
Patient Teaching
• Take as prescribed- do not miss a dose- if a dose is
missed, do not take a double dose
• Do not take other meds unless OK by your doctor
• Do not substitute with generic med
• EKG and electrolytes needed periodically
• Learn to count your pulse for a full minute- hold
med if less than 60 in an adult and less than 90 in
an infant, less than 70 in a child or adolescent
• Call health care provider if heart rate exceeds 100
and/or is irregular
• May be on salt restrictions
• Notify physician if weight gain of 2 lbs in 1 day or 5
lbs in 1 week
Lifespan Considerations
• Children
• Small window of safety
• Take care with calculating and measuring
• Elderly
• Widely used- many side effects are seen,
particularly dysrhythmias
• Reduced dosages are usually required due to
impaired renal and/or liver function
• Many commonly used drugs in the elderly
increase serum digoxin levels
Antidysrhythmic Drugs
• These drugs affect the heart’s electrical
conduction system
• Primarily used for tachydysrhythmias
• Convert rhythms
• Correct fast rates when cardiac output
is impaired
• For fatal dysrhythmias
Definitions
• Automaticity- the heart’s ability to
generate an electrical impulse- the
SA node normally has the highest
degree of automaticity
• Conductivity- the ability of cardiac
tissue to transmit electrical
impulses
Classes
• Class I- Sodium Channel Blockers
• 1A- quinidine (Quinaglute)
• 1B- lidocaine (Xylocaine)
• 1C- flecainide (Tambocor)
• Class II- Beta Adrenergic Blockers- propranolol
(Inderal)
• Class III- Potassium Channel Blockers- amiodarone
(Cordarone)
• Class IV- Calcium Channel Blockers- diltiazem
(Cardizem)
• Others- such as adenosine (Adenocard)- short half
life, acts like calcium channel blockers
Mechanism of Action
• Drugs used for rapid dysrhythmias-
• Reduce automaticity (spontaneous
depolarization of myocardial cells)
• Slow conduction of electrical impulses
through the heart
• Prolong the refractory period of
myocardial cells (right after ventricular
contraction, when the cardiac cells
cannot respond to stimuli)
Nursing Care
• Assess for conditions that may cause dysrhythmias
and treat- such as MI, electrolyte imbalance, drug
therapy, tissue ischemia, chronic lung disease
• Caution to avoid habits that will precipitate
dysrhythmias- such as smoking, caffeine,
overeating, alcohol intake, stimulant drugs, stress,
fever
• Monitor apical heart rate and rhythm and BP
• Check EKG and lab reports of serum electrolytes
and any drug levels, such as digoxin or phenytoin
• Adverse effects may include heart blocks,
dysrhythmias, hypotension, dizziness
Patient Teaching
• Take medications exactly as prescribed- taking
with meals may decrease gastric upset
• Know the name of your drug and what therapeutic
effects and side effects to expect
• You will need frequent medical supervision for
measurements of heart rate, BP, lab tests and EKG
• Try to identify triggers for irregular heart rate and
avoid
• Avoid over-the-counter cold medicines, appetite
suppressants, and antisleep medications
• Report dizziness or fainting
Lifespan Considerations
• Children
• Used less frequently than in adults
• Less information available about what is
effective
• Digoxin is the only FDA approved
antidysrhythmic drug in children
• Elderly
• Dysrhythmias are common but only
those causing symptoms of circulatory
impairment should be treated with these
drugs because they may experience
serious adverse drug effects
Antianginal Drugs
• Used to treat the pain of inadequate myocardial
oxygen supply
• Two classes of drugs are used to treat angina-
• Nitrates
• Beta adrenergic blockers
• Adjunctive drugs-
• Aspirin
• Antilipemics
• Antihypertensives
• Calcium channel blockers
Mechanism of Action
• Nitrates- nitroglycerin (Nitrostat)
• Relax smooth muscles in vessel walls- causes
vasodilation
• Beta blockers- propanolol (Inderal);
metoprolol (Lopressor)
• Block sympathetic stimulation of the heart-
results in reduction in heart rate and myocardial
contractility- improves coronary blood flow
• Calcium channel blockers- diltiazem
(Cardizem)
• Vasodilate, decrease force of contraction and
slow conduction system- improves myocardial
blood flow
Goals of Therapy
• Relieve acute anginal pain
• Reduce the number and severity of acute
attacks
• Improve exercise tolerance and quality of
life
• Delay progression of CAD
• Prevent MI
• Prevent sudden cardiac death
Nursing Care
• Assess chest pain- type, where, how long,
radiation, associated symptoms
• Oxygen if needed
• Assess meds taken
• Assess apical pulse, BP, EKG, serum
cholesterol, cardiac enzymes
• Withhold if systolic BP is less than 90
• IV nitroglycerin requires a special infusion
set
Patient Teaching
• Keep nitro tabs in original container in easy to
reach location- replace after 3 months-decomposes
if exposed to heat, light, moisture, or air
• May cause headache or dizziness- sit or lie down
when taking for 30 minutes
• Should taste burning or stinging, if not it is not
potent enough
• Take every 5 minutes X3 for chest pain if needed- if
no relief, seek care
• If using ointment or patch- place over nonhairy
area, do not rub, rotate sites, clean well after
removing- don’t place below elbow or knee level
• Avoid meds that stimulate the heart
• Avoid alcohol and smoking
Lifespan Considerations
• Children-
• Safety and effectiveness have not been
established- nitroglycerin has been used
IV for heart failure and in the OR for BP
control
• Elderly-
• Commonly used- watch for dizziness,
monitor BP