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Anatomy and Physiology

To understand what occurs in heart failure, it is useful to be familiar with the anatomy of

the heart and how it works. The heart is composed of two independent pumping

systems, one on the right side, and the other on the left. Each has two chambers, an

atrium and a ventricle. The ventricles are the major pumps in the heart.

The external structures of the heart include the ventricles, atria, arteries, and veins.

Arteries carry blood away from the heart while veins carry blood into the heart. The

vessels colored blue indicate the transport of blood with relatively low content of oxygen

and high content of carbon dioxide. The vessels colored red indicate the transport of

blood with relatively high content of oxygen and low content of carbon dioxide.

The Right Side of the Heart

The right system receives blood from the veins of the whole body. This is "used" blood,

which is poor in oxygen and rich in carbon dioxide.

The right atrium is the first chamber that receives blood.

The chamber expands as its muscles relax to fill with blood that has returned

from the body.

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The blood enters a second muscular chamber called the right ventricle.

The right ventricle is one of the heart's two major pumps. Its function is to pump

the blood into the lungs.

The lungs restore oxygen to the blood and exchange it with carbon dioxide,

which is exhaled.

The Left Side of the Heart

The left system receives blood from the lungs. This blood is now oxygen rich.

The oxygen-rich blood returns through veins coming from the lungs (pulmonaryveins) to the heart.

It is received from the lungs in the left atrium, the first chamber on the left side.

Here, it moves to the left ventricle, a powerful muscular chamber that pumps the

blood back out to the body.

The left ventricle is the strongest of the heart's pumps. Its thicker muscles need

to perform contractions powerful enough to force the blood to all parts of the

body.

This strong contraction produces systolic blood pressure (the first and higher

number in blood pressure measurement). The lower number (diastolic blood

pressure) is measured when the left ventricle relaxes to refill with blood between

beats.

Blood leaves the heart through the ascending aorta, the major artery that feeds

blood to the entire body.

The Valves

Valves are muscular flaps that open and close so blood will flow in the right direction.

There are four valves in the heart:

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The tricuspid regulates blood flow between the right atrium and the right

ventricle.

The pulmonary valve opens to allow blood to flow from the right ventricle to the

lungs.

The mitral valve regulates blood flow between the left atrium and the left

ventricle.

The aortic valve allows blood to flow from the left ventricle to the ascending

aorta.

The Heart's Electrical System.

The heartbeats are triggered and regulated by the conducting system, a network of

specialized muscle cells that form an independent electrical system in the heart

muscles. These cells are connected by channels that pass chemically caused electrical

impulses.

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Pathophysiology

Predisposing Factor:

Age

gender

Precipitating Factor: Sedentary Lifestyle

Diet

Tobacco Life

History of stroke

Decreased elasticity of blood vessels and formation of plaques on blood vessels

Narrowing of the blood vessels

Necrosis and scarring of the vascular endothelium

Impediment of blood flow to the body

Excessive stretching of the myocardial muscle

Increased Preload

Increased workload of the heart

Dilation of the ventricles

Increased stretching of the myocardial muscle

A

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Ineffective cardiac contraction and increase O2 demand of cardiac muscle cells

Decreased contraction of cardiac muscle

Decreased cardiac output and systemic perfusion

Activation of neurothermal pathways in order to increase circulating blood vessels

Cardiac Remodelling

Continued neurohormonal stimulation

Decreased blood filling

Increased stroke volume and Decreased cardiac output

Inadequate perfussion Increased wall tension

B C

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B

Pallor Decreased blood flow

to the kidneys

Decrease perfusion in

the coronar arteries

Increase Pulmonar

Pressure

Kidneys Produces

hormones

Salt and water

retention

Edema

Fatigue and weakne

Conversion of aerobic

metabolism to

anaerobic metabolism

Deprivation of cardiac

muscles of nutrients

needed for survival

Normal balance

between oxygensupply and demand is

disrupted

Ischemia

Decreased adenosineCauses reduce

contractility

Decrease Cardiac

output

Bradycardia

Lactic acid prod.

Irritation of

m ocardiac cells

Chest Pain

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C

Separation of mitral

valves leaflets

Increase pulmonary

pressure

Impaired left

ventricular relaxation

Increase diastolic pressure exceedinghydrostatic and osmotic pressure in

pulmonary capillaries

Increased capillary

pressure in the lungs

Fluid shifts from thecirculating blood into the

interstitium, bronchioles,

bronchi and alveoli

Increased capillary

pressure in the lungs

Decreased lung

expansion

Dsypnea Fluid trapped in

pulmonary treesBilateral Crackles