3. Heart Failure
● Old term: Congestive Heart Failure
● Definition: Progressive condition in which the heart is not
able to pump blood at a rate sufficient to meet the
metabolic demands of the peripheral tissue
● Decreased cardiac output, increased congestion
4. Types of heart failure
1) Depending of onset:
Chronic heart failure: gradual development of HF
Acute heart failure: sudden development of HF
5. 2) Depending on output:
Systolic dysfunction: decrease in Ejection
Fraction(EF)
Diastolic dysfunction: inability of heart chamber to
expand and fill sufficiently during diastole
2) Left- or right-sided HF
6. Causes of heart failure
Left-sided heart failure Right-sided heart failure
● Ischemic heart
disease(IHD) - Most
common cause
● Hypertension
● Aortic and mitral valve
disorders
● Myocardial diseases
Right-sided valvular heart
disease
Lung disorders such as:
● Emphysema
● Chronic bronchitis
● Pulmonary
hypertension
7. Pathogenesis of heart failure
- Takes time for congestive heart failure to develop, as heart
has the ability to compensate with various mechanisms
- These compensatory mechanisms maintain cardiac output
by increasing diastolic ventricular filling pressure and end-
diastolic volume
- Mechanisms include:
1. Frank-Starling mechanism(or Starling’s Law)
2. Myocardial hypertrophy
3. Activation of neurohumoral system
8. 4. Release of norepinephrine
5. Activation of RAA system
6. Release of ANP
9. 1. Frank-Starling mechanism(or Starling’s Law): the
greater the volume of blood flowing into the ventricle,
more is the stretching of the walls of the heart and more is
the force of contraction of the heart
2. Myocardial hypertrophy: chamber may or may not dilate
3. Activation of neurohumoral system: to increase heart
function by regulating filling volume and pressure
10. 4. Release of norepinephrine: increases heart rate,
myocardial contraction and vascular resistance
5. Activation of renin-angiotensin-aldosterone system:
Decreased EF → decreased blood supply to kidney →
activation of RAAS → retention of salt and water →
increased fluid volume
6. Release of Atrial Natriuretic Peptide(ANP): tries to
lower blood pressure in response to RAAS, but ultimately
is unable to
11. Mechanism of heart failure
LVF/RVF → Reduced cardiac output
↓
Compensatory mechanisms:
1) Neurohumoral system
2) Cardiac compensatory mechanisms
12. Activation of RAAS:
Causes sodium and water retention
↓
Increased intravascular volume
Sympathetic nervous system:
Causes vasoconstriction
Increased blood pressure and cardiac workload
↓
Further stress on myocardium
↓
CONGESTIVE HEART FAILURE
1) Neurohumoral activation
13. Tachycardia and increased myocardial contractility
↓
Increased cardiac workload
↓
Compensatory hypertrophy and dilatation
2) Cardiac compensatory mechanisms
14.
15. References:
● Dr. Ramadas Nayak - Textbook of Pathology for Allied
Health Sciences
Questions:
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