2. Introduction
• Heart failure is defined as the pathophysiologic statein which impaired cardiac
function is unable to maintain an adequate circulationfor the metabolic needs of
the tissues of the body. It may be acute or chronic.
• The term congestiveheart failure (CHF) is used for the chronic form of heart
failure in which the patient has evidence of congestionof peripheral circulation
and of lungs. CHF is the end-result of various forms of serious heart diseases.
Etiology
Heart failure may be caused by one of the following factors, either singly or in
combination:
1. INTRINSIC PUMP FAILURE
2. INCREASEDWORKLOAD ON THE HEART
3. IMPAIREDFILLING OF CARDIAC CHAMBERS
3. 1. INTRINSIC PUMP FAILURE
The mostcommon and most important cause of heart failure is weakening of the
ventricular muscle due to disease so that the heart fails to act as an efficient pump.
i)Ischemicheart disease
ii) Myocarditis
iv) Metabolic disorders e.g. beriberi
v) Disorders of the rhythm e.g. atrial fibrillation and fl utter.
2. INCREASED WORKLOADON THE HEART
• Iincreased mechanical load on the heart results in increased myocardialdemand
resulting in myocardial failure.
• It may be presser load or volume load.
i)Increased pressure load
a) Systemicand pulmonary arterial hypertension.
b) Valvular disease e.g. mitral stenosis,aortic stenosis,pulmonary stenosis.
c) Chronic lung diseases
4. ii)Increased volume load occurs when a ventricle is required to eject more than
normal volume of the blood resulting in cardiac failure.
a) Valvular insufficiency
b) Severe anemia
c) Thyrotoxicosis
d) Arteriovenousshuntse) Hypoxia due to lung diseases.
3. IMPAIREDFILLINGOF CARDIAC CHAMBERS
Decreased cardiac output and cardiac failure may result from extra-cardiac
causesor defect in filling of the heart.
• Cardiac tamponade e.g. haemopericardium,hydropericardium
• Constrictivepericarditis.
5. Heart failure may be acute or chronic, right-sided or left-sided
ACUTE AND CHRONIC HEART FAILURE
Depending upon whether the heart failure develops rapidly or slowly,it may be acute or
chronic.
Acute heart failure Sudden and rapid developmentof heart failure.
i) Larger myocardialinfarction
ii) Valve rupture
iv) Massive pulmonary embolism
v) Acuteviral myocarditis
vi) Acutebacterial toxaemia.
In acute heart failure, there is sudden reductionin cardiac output resulting in systemic
hypotension but oedema does not occur. Instead, a stateof cardiogenicshock and
cerebral hypoxia develops.
TYPES OF HEART FAILURE
6. More often, heart failure develops slowly as observed in the following states:
i) Myocardial ischaemia from atheroscleroticcoronary artery disease
ii) Multivalvular heart disease
iii) Systemicarterial hypertension
iv) Chronic lung diseases resulting in hypoxia and pulmonary arterial
hypertension
v) Progressionof acute into chronic failure. In chronic heart failure,
compensatorymechanisms like tachycardia, cardiac dilatation and cardiac
hyper trophy try to make adjustments soas to maintain adequate cardiac
output. The is often resultsin well-maintained arterial pressure and there is
accumulationof oedema.
.Chronic heart failure
7.
8. • Though heart as an organ eventually fails as a whole, but functionally,the left
and right heart act as in dependent units.
• The clinical manifestationsof heart failure result from accumulation of excess
fluid upstream to the left or right cardiac chamber whichever is initially affected.
Left-sided heart failure
It is initiated by stressto the left heart. The major causes are as follows:
• Systemichypertension
• Mitral or aortic valve disease (stenosis)
• Ischaemic heart disease
• Myocardial diseases e.g. cardiomyopathies,myocarditis.
The clinical manifestations of left-sided heart failure result from decreased
left ventricular output and hence there is accumulation of fluid upstream in the
lungs.
i) Pulmonary congestionand oedema causes dyspnoea.
LEFT-SIDED AND RIGHT-SIDED HEART
9. . ii) Decreased left ventricular output causing hypo perfusion and diminished
oxygenation of tissues e.g. in kidneys causing tubular necrosis and in skeletal
muscles causing muscular weakness and fatigue.
HYPERTENSIVE HEART DISEASE
• Hypertensive heart disease or hypertensive cardiomyopathyresults from systemic
hypertension of prolonged duration and manifestsby left ventricular hypertrophy.
• Even mild hypertension (blood pressure higher than140/90 mmHg) of sufficient
duration may induce hypertensive heart disease. It is the second most commonform
of heart disease.
10. Right-sidedheart failure occurs more often as a consequence of left-sided heart failure. However, some
conditions affect the right ventricle primarily, producing right-sided heart failure. These are as follows:
• As a consequence of left ventricular failure.
• Cor pulmonale in which right heart failure occurs due to intrinsic lung diseases.
• Pulmonary or tricuspid valvular disease.
• Pulmonary hypertension secondary to pulmonary thromboembolism.
• Myocardialdisease affecting right heart.
• Congenital heart disease with left-to-right shunt.
Whateverbe the underlying cause, the clinical mani-festations ofright-sided heart failure are upstream of
the right heart such as systemic(due to cavalblood) and portal venous congestion,and reduced cardiac
output. Accordingly,the pathologic changes are as under
i) Systemicvenous congestionin different tissues and organs e.g. subcutaneous edema on dependent
parts, passive congestionof the liver, spleen, and kidneys, ascites, hydrothorax, congestionof leg veins
and neck veins.
ii) Reduced cardiac output resulting in circulatory stagnationcausing anoxia, cyanosis and coldness of
extremities.
Right-sidedheart failure
11. Cor pulmonale (cor=heart;pulmonale=lung)or pulmonary heart disease is the right
heartdisease resulting from disorders of the lungs. It is characterizedright ventricular
dilatation or hypertrophy,or both. Thus, corpulmonale is the right-sided counterpartof
the hypertensive heart disease that affectsleft heart predominantly.
• Acute cor pulmonale occurs following massive pulmonary embolism resulting in
sudden dilatation of the pulmonary trunk,conusand right ventricle.
• Chronic cor pulmonale is more commonand is often preceded by chronic pulmonary
hypertension (page 466). Following chroniclung diseases can cause chronic pulmonary
hypertension and subsequentcor pulmonale:
1. Chronic emphysema
2. Chronic bronchitis
3. Pulmonary tuberculosis
4. Pneumoconiosis
5. Cysticfibrosis
COR PULMONALE
12. The most commonunderlying mechanism causing increased pulmonary blood
pressure(pulmonary hypertension)is by pulmonary vasoconstriction,activation of
coagulation pathwayand obliterationof pulmonary arterial vessels.
• Pulmonary hypertension causespressure overload on the right ventricle and
hence right ventricular enlargement.
• Initially, there is right ventricular hypertrophy,but as cardiac decompensation
sets in and right heart failure ensues, dilatation of right ventricle occurs. The
sequence of events involved in the pathogenesis of corpulmonale in early stage
the left heart failure manifestswith featuresof pulmonary congestionand
decreased left ventricular output, while the right heart failure presents with
systemicvenous congestionand involvement of the liver and spleen. CHF,
however,combinesthe featuresof both left and right heart failure.
