None — The Blood Vessels and Cardiovascular Disease
The circulatory system is a network of blood vessels that carry blood through the body. Oxygenated blood is pumped from the left side of the heart and travels through the arteries, branching out into smaller and smaller vessels. Eventually, the arteries connect with tiny vessels, called capillaries. The walls of the capillaries are very thin, enabling oxygen to be released from the red blood cells into the tissues. At the same time, waste gases are absorbed into the blood. The other end of the capillaries connects to the veins, the network of vessels that carry deoxygenated blood back to the right side of the heart. From here, the blood is sent to the lungs, where the waste gases are released and replaced with fresh oxygen. The oxygenated blood is then returned to the left side of the heart.
Cardiovascular disease is the name used to refer to conditions that affect the heart and blood vessels. The American Heart Association estimates 81.1 million Americans have one or more forms of cardiovascular disease. That amounts to one in three adults in the U.S. Cardiovascular disease is the leading cause of death in this country, killing 2,300 Americans each day. Some of the most common forms of cardiovascular disease include: high blood pressure, coronary heart disease, stroke and heart failure.
Fingertip Screening
Vascular reactivity refers to the ability of the blood vessels to respond to temporary changes in the need for blood flow. When more blood is needed for the tissues (like during exercise), the vessels widen. Constriction, or narrowing, of the blood vessels may occur in instances like extreme cold or shock, when the body needs to decrease blood to the extremities in order to provide more blood to the major organs. In early stages of cardiovascular disease (before symptoms become evident), vascular reactivity decreases.
Morteza Naghavi, M.D. of the University of Houston in Houston, TX, has invented a simple, non-invasive test to screen patients for vascular reactivity, and thus, potential cardiovascular disease. The test, called VENDYS®, is a type of digital thermal monitoring system.
VENDYS uses a fingertip temperature probe in conjunction with a traditional blood pressure cuff. The fingertip temperature is measured before the blood pressure arm cuff is inflated, giving doctors a baseline temperature reading. The cuff is inflated and held at the inflation state for about five minutes. Naghavi explains this blocks blood flow through the arm, causing fingertip temperature to fall in response to the decreased flow of warm blood. When the cuff is deflated, normal blood flow is restored and the fingertip temperature begins to rise. The rise in temperature is called the temperature rebound. It peaks within minutes of the cuff deflation, reaching a peak (the rebound measuring point) and then falling back to normal.
Naghavi says the higher and faster the temperature rebound, the better the vascular reactivity. That indicates the blood vessels are quickly responding to the changing flow of blood into the fingertips. On the other hand, if the temperature is slow to return to normal, the blood vessels are not responding as expected, possibly because they are not healthy.
Investigators have compared the results of VENDYS with those obtained through standard imaging (CT scans and X-rays) in patients being screened for plaque buildup in the coronary arteries. The researchers found patients who had more plaque in their coronary arteries had lower temperature rebound measurements with VENDYS.
The results show that VENDYS could be used as a screening tool for cardiovascular disease. Naghavi cautions the results would not be considered definitive. Rather, the results could determine which patients need further screening and testing. The extra cost of the device is expected to be minimal, about $50.00. Thus VENDYS could become an inexpensive screening tool in doctors' offices. In addition, the test could be used to follow patients and determine if treatments are having any effect on cardiovascular health.
Naghavi estimates VENDYS will be introduced into the marketplace in about a year-and-a-half. Eventually, it is hoped VENDYS will be available as an extra component to public blood pressure machines found in drug stores and other retail stores.
AUDIENCE INQUIRY
For information about VENDYS®, go to http://www.endothelix.com .
For general information on cardiovascular diseases: American Heart Association, http://www.heart.org.
National Heart, Lung and Blood Institute, http://www.nhlbi.nih.gov .