Surgery Involving the Heart

　　1. The heart-lung machine (pump-oxygenator1) is a valuable addition to the modern operating room. This machine has made it possible to perform many operations on the heart and other thoracic organs which could not otherwise be done. There are several types of machines in use, all of which serve as2 a temporary substitute for3 the patient’s heart and lungs.

　　2. The machine siphons off4 the blood from the large vessels entering the heart on the right side so that no blood passes through the heart and lungs. The blood is returned to the general circulation for body distribution through one of the large arteries. While passing through the machine, the blood is oxygenated by means of5 an oxygen inlet, and carbon dioxide6 is removed by various chemical means. These are the processes that normally take place between the blood and the air in the lung tissue. While in the machine, the blood is also “defoamed” to be sure that all air bubbles are removed, since such bubbles could be fatal to the patient by obstructing blood vessels. An electric motor in the machine serves as a pump during the surgical procedure to distribute the processed blood throughout the body by means of the artery mentioned above.

　　3. Diseased valves may become deformed and scarred from endocarditis so that they are ineffective and often obstructive. In some cases a special small knife can be inserted into the heart chamber and the valve can be cut so that it no longer obstructs the blood flow. The valve may even become partially functional. In other cases there may be so much damage that replacement is the only resort. Substitute valves made of7 plastic materials have proved to be a lifesaving measure for many patients. Very thin butterfly valves made of dacron or other synthetic material have also been successfully used.

　　4. Artificial hearts or parts of hearts designed to assist the ventricles in their pumping function have not proved as successful as the artificial valves. However, research continues and it is quite possible that an effective device may soon be ready for use. More spectacular is the transplantation of a human heart from the body of a person who has recently died. Tissues of the donor and the recipient should be as closely matched as possible to avoid rejection by the recipient’s antibody mechanism. This rejection syndrome is the most serious problem related to heart transplants.

　　练习：

　　1.Paragraph 1 ______

　　2.Paragraph 2 ______

　　3.Paragraph 3 ______

　　4.Paragraph 4 ______

　　A The Heart Transplantation

　　B How the Heart-lung Machine Works

　　C A Machine Making Many Kinds of Thoracic Operations Possible

　　D A Temporary Substitute for the Diseased Valve

　　E Operations on Cardiac Valves and Substitutes for Valves

　　F How Every Part of the Heart Performs Its Function

　　5.The blood is oxygenated and carbon dioxide in it is removed ______.

　　6.The heart-lung machine is an essential helper for surgeons ______.

　　7.Endocarditis may cause valves to be damaged ______.

　　8.It is extremely important in heart transplantation ______.

　　A and finally they fail to function properly

　　B to perform many surgical operations on the chest

　　C when it passes through the heart-lung machine

　　D and they no longer obstruct the blood flow

　　E to match tissues of the donor and the recipient

　　F when the ineffective valves are replaced by artificial ones

　　答案与题解：

　　1.C　本题答案主要在第一段第二句，该句说到没有人工心肺机许多胸外科手术就无法做。

　　2.B　第二段详细叙述了人工心肺机的工作原理，它是如何在手术期间代替心脏的功能的。

　　3.E　第三段讲述了缺损瓣膜的手术及其代用品。

　　4.A　第四段主要讲心脏移植及其代用品。

　　5.C　此问题的答案在第二段第三句，该句说的就是血液在通过人工心肺机时得以充氧并将二氧化碳排出。

　　6.B　本题是根据第一段前两句得出的结论，它是胸外科医生必不可少的助手。

　　7.A　第三段第一句讲的就是本题的意思。

　　8.E　文章最后两句说组织匹配是为了避免排异反应，故它是心脏移植中最重要的事情。

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