Heart attack

Definition

A heart attack is a colloquial term referring to a serious, sudden heart
condition that presents as varying degrees of chest pain, weakness,
sweating, nausea and vomiting, sometimes causing loss of consciousness. A
heart attack is a medical emergency.

The medical term for a heart attack is acute myocardial infarction, often
abbreviated as AMI or MI. "Acute" means sudden, "myo" refers to muscle, and
"cardium" refers to a part of the heart, in this case to the heart muscle
(myocardium). "Infarction" is a medical term describing tissue death
(necrosis) caused by an obstruction of blood flow.

Causes

The underlying mechanism of a heart attack is the destruction of heart
muscle cells due to a lack of oxygen. If these cells are not supplied with
sufficient oxygen by the coronary arteries to meet their metabolic demands,
they die.

A common cause of heart attack is atherosclerosis: a gradual buildup of
fat-containing substances (plaque) in the walls of the arteries can erupt
and cause a blood clot (thrombus) to form; this thrombus can then cause a
sudden clogging of the coronary arteries. This is one reason why older
people are more susceptible to heart attacks.

Heart attacks can also occur if the work load of the heart suddenly rises
and the necessary oxygen cannot be supplied quickly enough. This is why
extreme stress or physical exertion can result in heart attacks.

Diagnosis

The classical symptom of a heart attack is chest pain. However it is present
only in 65-69% of cases. Pain most characteristic of a heart attack is
described as "intense pressure" ("like an elephant sitting on your chest")
but can also be a sharp or stabbing pain. The pain may radiate to the left
arm, neck or the back and can be slight, moderate, or severe.

Some associated symptoms include dizziness, nausea, shortness of breath and
diaphoresis (excessive sweating). In the absence of these symptoms, sharp
chest pain which goes away promptly when the patient stops moving chest and
arm muscles often is not associated with a heart attack; but a sharp chest
pain that persists despite lack of movement is a strong indicator of a heart attack.

Heart attacks sometimes occur with atypical pain or in the absence of
classical symptoms, particularly in women, who may experience simply chest
discomfort, a sensation of uncomfortable chest pressure, cold sweats,
nausea, or pain in the arm, back, jaw, or stomach (so called anginal
equivalents). Women are just as likely to die of a heart attack as men.

First Aid

If you are having a heart attack, call for help immediately. Many people
have died needlessly because they were afraid or unwilling to admit that
they were having a heart attack until too late. If possible, take an aspirin
because it makes blood clots less likely to form. Find other people who can
get help and administer CPR should your heart stop beating.

A heart attack is a life-threatening medical emergency which demands
immediate activation of the emergency medical services. Immediate transport
by ambulance to a hospital where advanced cardiac life support is available
needs to be arranged. Calm the patient as much as possible.

If the patient is conscious and able to swallow, it may be advisable to give
one baby aspirin. Look to see if the patient has nitroglycerin tablets or
patches available, particularly if they have been the victim of prior heart
attacks. As a first-aider, you may assist a conscious patient in taking
these self-rescue medications.

In wilderness first aid, a possible heart attack justifies medical
evacuation by the fastest available means, including MEDEVAC, even in the
earliest or precursor stages. The patient will rapidly be incapable of
further exertion and have to be carried out. Note the correlation between
age, exertion and the onset of chest pain.

Field Care (for EMTs)

Transport immediately if breathing and pulse are present. ("Load and go.")
Place on oxygen therapy by mask and calm the patient. Monitor closely (with
electrocardiogram if available).

Be prepared to apply advanced cardiac life support including defibrillation
and (at the paramedic level) injection of medications into the heart per
protocol. If equipment is not available, perform CPR if the heart stops beating.

About 20% of patients die before they reach the hospital; the cause of death
is often fibrillation.

Clinical Treatment

A heart attack is treated with thrombolytic drugs (such as urokinase,
streptokinase, or alteplase (recombinant tissue plasminogen activator)),
heparin, and medication to prevent arrhythmia. Immediate or delayed
treatment with angioplasty or coronary artery bypass surgery is another
option. Following a heart attack, a patient's heart rhythm is closely
monitored: antiarrhythmic medication may be needed. Some people at risk for
coronary disease are prescribed medication to prevent heart attacks (such as
aspirin or Plavix (clodipogrel)).

Doctors traveling by commercial aircraft: oxygen is available on board and
the first aid kit on jetliners contains basic cardiac drugs used in advanced
cardiac life support. If treating a potential heart attack while in the air,
ask the stewardess to get this kit for you. The pilot will divert the flight
to the nearest airport.