Over time, they become laden with cholesterol products, particularly LDL, and become foam cells. A cholesterol core forms as foam cells die. In response to growth factors secreted by macrophages, smooth muscle and other cells move into the plaque and act to stabilize it. A stable plaque may have a thick fibrous cap with calcification. If there is ongoing inflammation, the cap may be thin or ulcerate. Exposed to the pressure associated with blood flow, plaques, especially those with a thin lining, may rupture and trigger the formation of a blood clot (thrombus). The cholesterol crystals have been associated with plaque rupture through mechanical injury and inflammation. Other causes
Atherosclerotic disease is not the only cause of myocardial infarction, but it may exacerbate or contribute to other causes. A myocardial infarction may result from a heart with a limited blood supply subject to increased oxygen demands, such as in fever, a fast heart rate, hyperthyroidism, too few red blood cells in the bloodstream, or low blood pressure. Damage or failure of procedures such as percutaneous coronary intervention or coronary artery bypass grafts may cause a myocardial infarction. Spasm of coronary arteries, such as Prinzmetals angina may cause blockage. Tissue death
If impaired blood flow to the heart lasts long enough, it triggers a process called the ischemic cascade; the heart cells in the territory of the blocked coronary artery die (infarction), chiefly through necrosis, and do not grow back. A collagen scar forms in their place.
BII-phobics may be given pictures of needles or blood, asked to illustrate needles or scenes with blood, or to speak about their phobic triggers. This systematically progresses to the point of the individual directly confronting a phobic stimulus: being given a needle, witnessing blood being drawn, etc. As exposure continues, it is expected that the phobic response will become less pronounced, and symptoms less debilitating.While AT targets the phobia’s physiological response, aiming to raise blood pressure and directly prevent fainting, AR focuses mainly on helping an individual avoid the phobia’s associated anxiety. A phobic will learn progressive relaxation techniques to help to calm themselves upon exposure to a trigger. Temporary alleviation of symptoms
Drinking water before a triggering experience such as blood donation has been indicated to aid in prevention of a fainting response. Water will increase sympathetic nervous system activation, raising blood pressure and combating vasovagal response.Certain physical maneuvers also have the capacity to temporarily boost blood pressure, alleviating symptoms of pre-syncope like lightheadedness by boosting blood flow to the brain. These include the phobic individual crossing their legs, making tight fists with both hands, or engaging muscles of the trunk or arms. Coughing, which can similarly increase cranial blood flow, can also be useful as a coping mechanism to avoid pre-syncope and syncope.Symptoms of a phobic response are generally able to be fully alleviated within a few minutes simply by removing the phobic trigger.