The fully expanded lung is covered by a thin membrane called the pleura.

The inside of the chest wall is also covered with the same membrane and, between the two layers of pleura is a thin film of liquid which enables the two surfaces to glide smoothly over each other as the person breathes.

Pleurisy is inflammation of these pleural membranes.

In pneumothorax, air enters this potential cavity between the two pleural layers and air pressure causes the underlying lung to collapse.

In the past, an artificial pneumothorax was created in some cases of tuberculosis so as to collapse and rest the lung.

A pneumothorax may occur from a penetrating wound of the chest or it may arise spontaneously, usually as the result of rupture of a small bleb, or blister-like projection, on the lung surface.

This bulla or bleb is usually a small congenital abnormality. Rupture usually occurs in the teens or early twenties, and men suffer from it five times as commonly as women.

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These bypass channels can be used on one or all three arteries.

There is no doubt that this type of operation can produce substantial benefits for the patient and can improve the quality of his life. Although results seem to indicate that this procedure can prolong life in those with coronary artery disease, there has not been sufficient time to prove it.

The main reason for surgery is severe angina that interferes with the reasonable quality of life and stops him from carrying out normal daily activities.

Operation is also considered in unstable angina. There are several states, coronary insufficiency, crescendo angina and Prinzmetal angina, where the condition appears to worsen over several days and may end in a complete block of the artery. Urgent operation is considered to prevent this catastrophe.

As a result of myocardial infarction, several structural complications may develop within the heart and affect the valves, the dividing septum or the wall of the chambers of the heart. Operation may be necessary to repair this damage and it may be opportune to carry out bypass surgery at the same time.

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