| Heart Attack (Acute Myocardial Infarction) Heart attack (or acute myocardial infarction (AMI)) occurs when one of the blood vessels in the heart muscle becomes blocked and the blood flow in the muscle becomes interrupted. Due to the lack of oxygen supply, heart muscle cells will become damaged and may undergo cell death (myocardial necrosis). The blockage of blood vessel is usually caused by the rupture of atherosclerotic plaque resides on the vessel wall. Atherosclerotic plaque is matrix of fatty materials, proteins and cells that accumulate on the vessel. This matrix slowly grows in size over a period of decades. As these plaques grow, they narrow and weaken the vessel walls. Some of the plaques eventually rupture and expose substances that lead formation of blood clots. These blood clots then block the blood flow the blood vessel and lead to heart attack. If you are experiencing symptoms of a heart attack, immediately call 911 for emergency medical help for treatment to limit the amount of damage to your heart. Heart Attack Symptoms Discomfort, heaviness, or pressure in the chest or arm Radiating pain to the back, jaw, throat or arm Shortness of breath, choking feeling, nausea, vomiting or dizziness, extreme weakness, rapid or irregular heartbeats If you think you are experiencing a heart attack, immediately call 911 for emergency medical help for immediate treatment to limit the amount of damage to your heart. Diagnosis Upon arrival to the emergency room, electrocardiogram (also called EKG or ECG) would be used to evaluate the health of your heart. This is achieved by monitoring the electrical activity of the heart through small electrode attached to the skin of your chest, arms, and legs. The results from EKG allow your doctor to diagnose a heart attack by assessing the blood flow in the heart muscle and the rhythm of the heart. Cardiac enzyme test for cardiac troponin (cTn) will also be performed to evaluate the extent of heart damage. Cardiac troponin isoform T (cTnT) is currently the preferred biomarker for the diagnosis and prognosis of acute cardiac diseases. Normally, only a low level of cTnT is present in your blood. However, if your heart muscle is injured by a heart attack, damaged heart muscle cells would undergo cell death and release cTnT into the bloodstream. Only a small volume of blood sample from your arm is required for this enzyme test. Current assays can detect cTn at levels from 0.01 to 1 microgram per liter. The European Society of Cardiology/American College of Cardiology task force has defined the upper limit of normal troponin level as level above the 99th percentile in a normal healthy population. The troponin enzyme level and 12-lead electrocardiogram (EKG) results are generally used together to stratify patients into risk groups when they are being admitted to the hospital. |
Heart Attack
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