The ST segment refers to the flat section of anelectrocardiogram (ECG)reading and represents the interval between jagged heartbeats.当一个人心脏病发作时，此段将不再平坦，但会出现异常升高。
STEMI是acute coronary syndrome (ACS).冠状动脉内斑块破裂时会发生急性冠脉综合征。造成动脉部分或完全阻塞。阻塞本身是由破裂区域周围形成血凝块引起的。
When obstructed,the portion of the heart muscle serviced by that artery will quickly suffer from a lack of oxygen,打电话ischemia.胸痛心绞痛）这通常是第一个迹象。If the obstruction is extensive enough,一些心肌会开始死亡，resulting in myocardial infarction.
- 如果冠状动脉完全阻塞，导致心肌组织死亡，we refer to that as STEMI,最糟糕的ACS形式。
- However,在某些情况下，凝块会形成，dissolve,and re-form during a period of hours or days without causing a fixed obstruction.当这种情况发生时，the person may experience on-again-off-again angina even when resting.This type of ACS is called不稳定型心绞痛.
- In between STEMI and unstable angina is a condition some refer to as a "partial heart attack." This occurs when the obstruction doesn't completely stop the blood flow.当一些细胞死亡发生时，肌肉的其他部分会存活下来。医学术语是非ST段抬高型心肌梗死。（NSTEMI).
Regardless of how an ACS event is classified,it is still considered a medical emergency since unstable angina and NSTEMI are often early warning signs of a major heart attack.
STEMI will typically result in intense pain or pressure in or around the chest,经常放射到颈部，jaw,shoulder,or arm.大量出汗，breathlessness,一种即将到来的毁灭感也很普遍。At times,这些迹象可能不太明显，表现为非特异性或全身性症状，如：
- Pain around the shoulder blades,手臂，chest,jaw,left arm,or upper abdomen
- Nausea and vomiting
- Fatigue or sudden exhaustion
- Dizziness or lightheadedness
- Increased or irregular heart rate
As a general rule of thumb,anyone at significant risk of a heart attack should pay close attention to any unusual symptom arising from above the waist.
在大多数情况下，the diagnosis of STEMI can be made quickly once the person is under medical care.A review of symptoms,accompanied by the evaluation of the ST segment on the ECG,通常足以让医生开始治疗。A review ofcardiac enzymesmay also help but usually arrives well after acute treatment is started.
It is important to stabilize the person as quickly as possible.In addition to pain and distress,STEMI can cause sudden death due to心室颤动(a serious disturbance of the heart rhythm) or acute heart failure (when the heart cannot pump enough blood to properly supply the body).
心脏病发作后，the muscle itself may be left with substantial permanent damage.慢性心力衰竭是一个常见的后果，as is the increased risk of dangerous cardiac arrhythmias (irregular heartbeats ).
这需要速度。除非动脉在堵塞后的三小时内被打开，at least some permanent damage can be expected.一般来说，如果动脉在攻击后的前六小时内畅通，大部分的损伤可以减至最小。直到12小时，可以避免一些损坏。After that,疏通动脉的时间越长，损失越大。
Once the acute phase of treatment is over and the blocked artery is reopened,there is still a lot that has to be done to stabilize the heart,减少再次心脏病发作的几率。