Cardiac Path Online
Pathology of Congestive Heart Failure
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.
Congestive heart failure 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:
1. Systemic hypertension (most common cause).
3. Mitral or aortic valve disease. Mitral Valve Lesions
4. Primary myocardial disease.
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:
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.
(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.
1. Congestion and edema of portal and dependent peripheral sites (Eg: feet, ankle, sacrum) and effusions in pleura and peritoneum (ascites).
2. Hepatomegaly - 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.
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.
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