Heart Failure

Learning outcomes:
By the end of this session and with appropriate self study you should be able to:
?explain the pathophysiology of heart failure
?describe the clinical characteristics of the principal types of heart failure, and the circumstances which lead to its development
?identify targets for drug action for the manipulation of cardiac output
?describe the principles involved in the general management of heart failure, and the categories of drugs used in its therapy
In mild to moderate forms of heart failure, cardiac output is normal at rest and only becomes impaired when the metabolic demand increases during exercise or some other form of stress.

Etiology
coronary artery disease (CAD) has become the
predominant cause in men and women and isresponsible for 60–75% of cases of HF.
•Hypertension contributes to the development of HF
in 75% of patients, including most patients with
CAD.
• Both CAD and hypertension interact to augment
the risk of HF, as does diabetes mellitus
Etiology
•20-30% unknown ( dilated cardiomyopathy)
•Viral
•Alcoholic & toxic
•Genetic
•Autosomal dominant
•Anaemia & arteriovenous fistula
Pathogenesis of heart failure with a depressed ejection fraction
•However, with time the sustained activation of these systems can lead to
secondary end-organ damage within the ventricle, with worsening left
ventricular remodeling and subsequent cardiac decompensation
•there is activation of a family of countervailing vasodilatory
molecules, including the atrial and brain natriuretic peptides (ANP and
BNP), prostaglandins (PGE2 and PGI2), and nitric oxide (NO), that
offsets the excessive peripheral vascular vasoconstriction
•The decreased cardiac output in HF patients results in an "unloading"
of high-pressure baroceptors in the left ventricle, carotid sinus, and
• with a resultant generalized increase in efferent sympathetic tone, and
non-osmotic release of arginine vasopressin (AVP) from the pituitary.
• AVP [or antidiuretic hormone (ADH)] is a powerful vasoconstrictor
that increases the permeability of the renal collecting ducts, leading to
•These afferent signals to the CNS also activate efferent sympathetic
nervous system pathways that innervate the heart, kidney, peripheral
vasculature, and skeletal muscles.