First Sentence

"Psychological factors play a very important role in the existence and formation of heart diseases, especially coronary heart disease (CHD). Nowadays, heart diseases especially CHD which its clinical spectrum varies from silence ischemia to stable angina, unstable angina, myocardial infection and sudden heart death is one of the three main causes of death in the industrial countries besides cancer and brain stroke. Fifty million people die annually around the world; 12 million of them die because of cardiovascular diseases.Stress can affect person's health through behavioral and physiologic changes. Stress can also lead to heart diseases through psychological changes. It seems that stress has direct effects on coronary arteries and heart muscles. Nontraditional risk factors, such as psychological traits, have been increasingly recognized as important contributors to the genesis and outcomes of coronary artery disease. Mental stress induces significant peripheral arterial vasoconstriction, with consequent increases in heart rate and blood pressure. These changes are thought to underlie the development of myocardial ischemia and other mental stress-induced adverse cardiac events."