How Are EKG Machines Used to Screen for Coronary Artery Disease (CAD)?
CAD (Coronary artery disease), is the most frequently found version of heart disease affecting adults in the US. According to the CDC’s recent statistics, nearly 500,000 people died from CAD related heart problems in 2005. In 2006, more than 630,000 people died from some form of cardiac disease, which accounted for 26 percent of all deaths that year in the United States. When one hears numbers like these, it is no surprise that heart disease is the #1 cause of death in the US, affecting women and men about equally. It is these statistics that make the case for more frequent and earlier screenings for high-risk patients. Oftentimes, these tests begin with a routine screening on an EKG machine in a doctor’s office.
In order to diagnose coronary artery disease (CAD), the heart must be tested under controlled “stress” conditions. A stress test is a nothing more than an EKG test that is conducted while the patient is working out on a treadmill, and it is here that a doctor will be able to detect blockages that could limit the flow of blood in the coronary arteries. Here, doctors look for at least a 50% diameter reduction in one of the three major arteries of the heart.
In the more widely used exercise cardiac stress test (ECST), a patient exercises according to a pre-set protocol that progressively increases the elevation and/or speed of the treadmill every three minutes. During this time, the patient’s heart rate, blood pressure, EKG and heart rhythm are monitored continuously. A blockage will cause certain changes in an EKG report, as well as the patient’s blood pressure and heart rate.
Not all EKG stress tests use a treadmill test. A secondary form of testing can be done by stimulating the heart through chemical stimulation. This form of testing is known as physiological stress testing.






