NSC2500: Heart Failure Pathophysiology and Pharmacology Report

This report provides a comprehensive overview of heart failure, encompassing its normal physiology, pathophysiology, risk factors, and causes. It delves into the pharmacology of Digoxin, a key medication in heart failure treatment, discussing its mechanism of action, pharmacokinetics, clinical considerations, and potential side effects. The report emphasizes the importance of understanding the pathophysiology and pharmacology of heart failure for registered nurses, highlighting the relevance to clinical practice. The report includes relevant references from medical journals and textbooks to support the information presented, offering a valuable resource for students in healthcare and related fields. The report also addresses the role of factors such as cardiac contractility, myocardial oxygen, and ventricular performance requirements in the context of heart failure, further enriching the understanding of the disease.

HEART FAILURE

Normal Physiology
 Cardiac contractility, myocardial
oxygen and ventricular performance
requirements are determined by
preload, afterload, substrate
availability, heart rate and viable
myocardium.
 Cardiac is the product of heart rate
and stroke volume (Dittmer, 2012).
 Preload is the heart's loading
condition at the end of it is filling and
relaxation phase.
 Afterload is considered to be the force
resisting the myocardial fibre
contraction at the beginning of systole.
 The cardiac reserve is the heart ability
for increasing its performance above
the level of resting in response to
physical and emotional stress.

Pathophysiology of Heart failure
RISK FACTORS
 High blood pressure
 Coronary artery disease
 Heart attack
 Diabetes
 Sleep apnea (Sosin, 2010).
 Congenital heart defects
 Valvular heart disease
 Viruses
 Alcohol use
 Tobacco use
 Obesity
 Irregular heartbeats

Pathophysiology of heart failure
Causes
 Coronary heart disease is considered to be the most common cause of
heart failure.
 Coronary heart disease narrows the supply of oxygen and blood to the
heart.
 Cardiomyopathy is the heart muscle disorder that weakens the function of
the heart (Braunwald, 2013).
 Congenital heart defect
 Heart valve disease
 High blood pressure
 Heart attack and diabetes
 HIV
 Anaemia
 Cancer treatment like chemotherapy
 Diabetes
 Alcohol or drug misuse

Pathophysiology of heart failure
Identification

Pharmacology
 Digoxin has been used for hundreds of
years in the treatment of heart failure.
 It is being produced naturally by the
foxglove flowering plant (Canfield,
Hansen & Rackner, 2012).
 It stimulates the muscle of the heart for
contracting more forcefully.
 It improves the symptoms of heart
failure and prevents further heart failure.

Pharmacodynamics and
Mechanism of Action
 Digoxin increases the efficiency and
strength of the heart contractions.
 It increases the contraction force of heart
muscle by inhibiting the activity of the
enzyme that controls the movement of
sodium, potassium and calcium (DeSilva,
2013).
 Inhibiting activity of the enzyme increases
the calcium in the muscle of the heart.

Pharmacokinetics
 Digoxin is being well observed in the intestinal
gastrointestinal tract.
 The oral bioavailability of Digoxin usually
remains high (70%-80%), even if the digoxin
metabolism within the gastrointestinal tract can
occur by hydrolysis in the acidic environment of
the stomach in some patients (Feldman, 2010).
 Digoxin has a large distribution volume
because of the high affinity for cardiac and
skeletal muscles, kidney and intestines.

Pharmacology
 Digoxin is used rarely as the first line
agent. It is being used in combination
with the other drugs.
 Digoxin increases the vagal tone that
leads to a decrease in the conduction
through the AV node (Katz & Konstam,
2009).
 Digoxin inhibits the sodium that
accumulates in myocytes.

Pharmacology
Side effects
 Breast enlargement
 Bradycardia
 Gastrointestinal effects (Braunwald,
2013).
 Loss of appetite
 Visual disturbances
 Skin rash
 CNS effects

Pharmacology
Clinical consideration
 Digoxin must be avoided in the heart block
because of the increase in the risk of the
conduction abnormalities.
 Digoxin is depicted eliminated through the
renal route and its dose should be decreased
in the patients with the failure of renal
(Canfield, Hansen & Rackner, 2012).
 Electrolyte abnormalities increase the digoxin
toxicity which includes hypomagnesaemia,
hypocalcaemia and hypokalemia.

Relevance to practice
 The registered nurses should gain a thorough
knowledge of pathophysiology and physiology of
heart failure.
 It will assist to determine the symptoms and signs
of heart failure (Canfield, Hansen & Rackner,
2012).
 The understanding of the pharmacology is also
important.
 The registered nurses should also gain an
understanding of the indications, contraindications
and side effects of the medicine.