Science & Technology in Action

5th Edition

Keeping the Arteries Open


Jnr Science Cert
The lives of many people with heart disease have been improved dramatically without major surgery placing drug-eluting stents into coronary arteries that have become partially blocked.
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Lesson excerpt

The Age of Medical Devices
In general, any device that is used for medical purposes, whether for diagnosis, treatment or surgery is called a medical device. This definition covers a very wide range of products including X-ray machines, thermometers and wheelchairs. The use of the correct device can have a significant impact, saving lives, extending life span and improving the quality of life for many people. One of the devices that has enriched many lives in the last decade is the stent. In this lesson, we examine the operation of the human cardio-vascular system and some associated medical problems. We then describe how the stent is used and discuss the advent of the most modern drug-eluting stent from Cordis in Co. Tipperary.

Overview of the Human Cardiovascular System
The cardiovascular system is made up of the heart and circulatory system. The circulatory system has two parts. Pulmonary circulation passes through the lungs. Systemic circulationpasses through the remainder of the body.

The heart is often described as a pump. Its function is to circulate blood. This blood plays a crucial role in the maintenance of life. It delivers oxygen and nutrients to the organs, tissues, and cells of the body and removes carbon dioxide and waste products. Oxygenated blood is transported around the systemic circuit from the left heart through a network ofarteries, arterioles (smallarteries), and capillaries. Twenty major arteries branch off into narrower arterioles and these branch off into even smallercapillaries. These capillariesdeliver the oxygen and nutrients. The blood then returns to the right heart through venules (smallveins) which connect to veins.

The right heart then sends this deoxygenated blood through thepulmonary artery to the lungs. Having picked up oxygen from the lungs, the blood returns to the left heart through the pulmonaryveins.

True or False?

  1. The accumulation of material on the wall of an artery is called plaque. true
  2. A stent is a metal tube inserted in an artery to counteract restrictions to blood flow caused by plaque build up. true
  3. A stent is not classified as a medical device. false
  4. The systemic circulatory system passes through the lungs. false
  5. The narrowing of an artery is called stenosis. false
  6. The polymer coating of a drug-eluting stent controls the rate of drug release. true
  7. Medical devices can be marketed without official authorisation. false
  8. Balloon angioplasty is used as an alternative to bypass surgery. true
  9. Arterioles are the largest blood vessels. false
  10. Stents are usually made of metal. true