Acute myocardial infarction (AMI) occurs when
oxygenated blood cannot reach the myocardium and muscle tissue
dies. It is caused when a coronary artery is completely blocked
or occluded.
AMI is caused by the same mechanism as angina except that AMI
results in tissue death and is not reversible. Patients with AMI
can experience:
AMI is a severe form of myocardial ischemia.
The blood flow through a coronary artery with atherosclerosis
is stopped by a blood clot or spasm. Next, the process
of anaerobic metabolism begins that produces lactic
acid and carbon dioxide. The accumulation of lactic
acid and carbon dioxide causes pain. A sustained
reduction in blood flow then causes tissue death.
Other conditions can reduce blood flow and cause myocardial
ischemia leading to AMI. These include shock, dysrhythmias
and pulmonary embolism. All prevent oxygen from reaching
the heart muscle.
Chest discomfort is one possible symptom of AMI.
The discomfort can occur in the center of the chest
that lasts more than a few minutes. It can go away
and come back. The discomfort can feel like fullness,
pressure, squeezing or pain.
Another symptom can be discomfort in other areas
of the upper body including pain or discomfort
in one or both arms, the back, neck, jaw or stomach.
Shortness of breath is another possible symptom
of AMI. Shortness of breath can occur with or without
chest discomfort.
Other associated symptoms can include dyspnea, nausea,
vomiting, diaphoresis, dizziness and a feeling of
impending death.