Ischemia means that the flow of blood (and therefore oxygen) to a part of the body has been reduced; cardiac ischemia means not enough blood and oxygen are flowing into the heart muscle, which can severely damage it and lead to a heart attack. In this episode of Second Opinion, you'll learn how to recognize the symptoms of cardiac ischemia, how it is treated, and how you can take steps to prevent it. 

The heart is a muscle, about the size of a fist, whose main job is to pump blood to all parts of the body, bringing needed nutrients and oxygen and delivering waste products to other organs for removal.  The heart has four chambers. The upper two are the atria (the right and the left atrium) and the lower two are the right and left ventricles. These chambers contract in a regular sequence, or rhythm (the heartbeat); the contractions enable the heart to pump blood.  The rhythm of the contractions is controlled by the heart's "pacemaker," a group of cells in the right atrium (called the sinoatrial node, SA node, or sinus node) that generate electrical impulses.  This is the "normal" rhythm, usually at a rate of 60 to 100 beats a minute.   These impulses travel across the heart's chambers, making them contract.

The coronary arteries are the blood vessels that bring blood to the heart.  When these arteries become hard and narrowed, the blood supply to the heart becomes reduced.  Arteries usually harden and narrow because they get clogged with a fatty substance called plaque.  This condition is known as coronary artery disease, coronary heart disease, or atherosclerosis and is a leading cause of cardiac ischemia.  Sometimes the plaque in the arteries ruptures or tears; a blood clot can form, badly blocking the artery, which can lead to a heart attack.  The coronary arteries can also be narrowed by spasm, and sometimes the narrowing is from a thick cholesterol deposit known as a "soft" plaque.

A heart attack  means the supply of blood and oxygen to the heart has been so drastically reduced that cells in the heart die.  The more severe the heart attack, the more heart muscle dies.  The technical name for the heart muscle is the myocardium, and the most widely used technical term for a heart attack is myocardial infarction.  But you may also hear the terms coronary thrombosis or coronary occlusion.  

Cardiac ischemia usually causes chest pain, a condition known as angina  or angina pectoris.  But you can have cardiac ischemia with no pain, no symptoms. This is called  "silent ischemia," and an individual may not be aware of the ischemic episode. One can even have a heart attack with no symptoms at all, called a silent heart attack.

But the good news is that heart attacks are no longer necessarily fatal.  Better understanding of the causes, signs and symptoms of heart disease plus new treatment methods mean that the majority of people who have a heart attack now survive.

Cardiac ischemia can also cause arrhythmia , an abnormal heart rhythm.  For more information about arrhythmia, watch the Heart Rhythm Disorder episode of Second Opinion and visit its web page.