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Congestive heart failure (CHF)
is the condition in which heart is unable to maintain an output
sufficient for the metabolic functions of the tissues and organs of
the body.
Most of the cases are due to the fall
of myocardial contractile function (systolic dysfunction).
Example: Ischemic injury ;
pressure or volume overload ; dilated cardiomyopathy .
Sometimes, failure may result from an
inability of the heart chambers to relax sufficiently during diastole
to fill the ventricles properly (diastolic dysfunction).
Example: Massive left ventricular
hypertrophy ; myocardial fibrosis ; deposition of amyloid ;
constrictive pericarditis.
CHF is characterized by diminished
cardiac output (forward failure) or stagnation of blood in the venous
system (backward failure) or both.
Adult myocytes cannot multiply,
pressure or volume stress causes adaptive hypertrophy of heart
followed by ventricular dilation ( to improve contraction by stressing
of myofibres according to Sterling law of Heart).
Other compensatory changes are increase
of blood volume by retention of salt and water and tachycardia. These
compensatory changes finally, become burden on cardiac function,
leading to progressive CHF.
Left-sided cardiac failure:
Causes:
1. Systemic hypertension (most common
cause).
2.
Ischemic heart disease.
3. Mitral or aortic valve disease.
MITRAL VALVE LESIONS
4. Primary myocardial disease.
Clinical presentation:
1. Due to obstruction to pulmonary
vascular out-flow there is pulmonary congestion and edema.
2. Reduction of renal perfusion causes:
(i) Salt and water retention (ii)
Ischemic acute tubular necrosis
(iii) Impairment of waste excretion
causing azotemia.
3. Reduced perfusion of central nervous
system causes hypoxic encephalopathy (irritability to coma).
Right-sided cardiac failure:
Causes:
1. Most common cause is the left
ventricular failure, causing pulmonary congestion and raised pulmonary
arterial pressure.
2. Intrinsic disease of lungs and
pulmonary vasculature causing obstruction to right ventricular
out-flow (cor pulmonale).
3. Pulmonary or tricuspid valve
disease.
4. Congenital heart disease in which
there is left-to-right shunt.
Example: (i)
Patent foramen ovale ; (ii) Patent ductus arterisus and
(iii) Interventricular septal defect.
5. Other causes:
i) Extracardiac circulatory failure.
Example: Haemorrhage ;
vasovagal syncope etc.
ii) Impaired atrial filling by external
compression. Example:
Constrictive pericarditis.
Clinical presentation:
1. Congestion and edema of portal and
dependent peripheral sites (Eg: feet, ankle, sacrum) and effusions in
pleura and peritoneum (ascites).
2. Hepatomagaly - Centrilobular
congestion and atrophy of central hepatocytes (nutmeg liver).
Centrilobular necrosis due to chronic
passive venous congestion may cause sinusoidal rupture with central
hemorrhagic necrosis followed by hemosiderosis , central fibrosis and
cardiac sclerosis.
3. Congestive
splenomegaly with
sinusoidal dilation, focal hemorrhage followed by hemosiderosis and
fibrosis.
4. Renal
congestion causes acute hypoxic tubular necrosis.
Microscopic features:
There is atrophy of the cardiac
myocytes with perinuclear deposition of lipofuscin and myocytolysis.
There is diffuse perivascular or interstitial fibrosis.
Fate of the patients:
Patients die of progressive congestive
heart failure or due to acute myocardian infarction or an arrythmia.
Visit:
Myocardial Infarction ;
Angina Pectoris.
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