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 Cardiovascular diseases are the number one killer of men and women. Although older
people are at a higher risk, such a sweeping generalization overlooks a large number
of younger people. For these reasons, early recognition and early treatment are the
keys to survival.
 The heart is divided down the middle into two sides, right and left, each with an upper
chamber called the atrium and a lower chamber called the ventricle.
 The largest of the four heart valves that keep blood moving through the circulatory
system in the proper direction is the aortic valve, which lies between the left ventricle
and the aorta, the body’s main artery.
 The tricuspid valve separates the right atrium from the right ventricle. The mitral
valve separates the left atrium from the left ventricle. Two semilunar valves, the
aortic valve and the pulmonic valve, divide the heart from the aorta and the
pulmonary artery.
 The heart’s electrical conduction system controls heart rate and helps to keep the atria
and ventricles working together. The mechanical pumping action of the heart can
occur only in response to an electrical stimulus. The electrical conduction system
consists of the sinoatrial (SA) node, the atrioventricular (AV) node, the bundle of His,
the right and left bundle branches, and the Purkinje fibers.
 Cardiac muscle cells have a special characteristic called automaticity. Automaticity
allows a cardiac muscle cell to contract spontaneously without a stimulus from a
nerve source. Impulses from the sinoatrial node cause the other myocardial cells to
contract.
 Regulation of heart function is provided by the brain via the autonomic nervous
system, the hormones of the endocrine system, and the heart tissue. Baroreceptors and
chemoreceptors sense abnormalities in pressure and chemical composition.
 The two phases of the cardiac cycle are systole, the pumping phase, and diastole, the
resting phase.
 During periods of exertion or stress, the myocardium requires more oxygen. This is
supplied by dilation of the coronary arteries, which increases blood flow.
 Chest pain or discomfort that is related to the heart usually stems from ischemia
(decreased blood flow) to the heart. The tissue soon begins to starve and, if blood
flow is not restored, eventually dies.
 Diminished blood flow to the myocardium is usually caused by atherosclerosis, a
disorder in which cholesterol and other fatty substances build up and form a plaque
inside the walls of blood vessels.
 Occasionally, a brittle plaque will crack, causing a blood clot to form. A blood clot
may break loose and begin floating in the blood, becoming what is known as a
thromboembolism. A thromboembolism is a blood clot that is floating through blood
vessels until it reaches an area too narrow for it to pass, causing it to stop and block
the blood flow at that point.
 Heart tissue downstream suffers from a lack of oxygen and, within 30 minutes, will
begin to die. This is called an acute myocardial infarction (AMI), or heart attack.
 Chest pain may be caused by a brief period when heart tissues do not get enough
oxygen. The discomfort associated with this is called angina. Angina pain is similar
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to the pain of an acute myocardial infarction (AMI), but responds to nitroglycerin
administration. However, angina can be a sign that an AMI will occur in the future.
Myocardial tissues that are ischemic but are not yet dying can cause pain called
angina. The pain of AMI is different from that of angina in that it can come at any
time, not just with exertion; it lasts up to several hours, rather than just a few
moments; and it is not relieved by rest or nitroglycerin.
In addition to chest pain or pressure, signs of AMI include sudden onset of weakness,
nausea, and sweating; sudden arrhythmia; pulmonary edema; and even sudden death.
Heart attacks can have three serious consequences. One is sudden death, usually the
result of cardiac arrest caused by abnormal heart rhythms called arrhythmias. These
include tachycardia, bradycardia, ventricular tachycardia (VT), and, most commonly,
ventricular fibrillation (VF).
The second consequence is cardiogenic shock. Symptoms include restlessness;
anxiety; pale, clammy skin; pulse rate higher than normal; and blood pressure lower
than normal. Patients with these symptoms should receive oxygen, assisted
ventilation as needed, and immediate transport.
The third consequence of AMI is congestive heart failure (CHF), in which the
damaged myocardium can no longer contract effectively enough to pump blood
through the system. The lungs become congested with fluid, breathing becomes
difficult, the heart rate increases, and the left ventricle enlarges.
Signs of CHF include swollen ankles from pedal edema, high blood pressure, rapid
heart rate and respirations, rales, and sometimes the pink sputum and dyspnea of
pulmonary edema.
Treat a patient with CHF as you would a patient with chest pain. Monitor the patient’s
vital signs. Give the patient oxygen via a nonrebreathing mask. Allow the patient to
remain sitting up.
In treating patients with chest pain, obtain a SAMPLE history, following the
OPQRST-I mnemonic to assess the pain; measure and record vital signs; ensure that
the patient is in a comfortable position, usually semireclining or half sitting up;
administer prescribed nitroglycerin and oxygen; and transport the patient, reporting to
medical control as you do.
If a patient is not responsive, you may perform the following, depending on the
patient’s age, weight, and your local protocol:
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Unresponsive adult or a child who is older than 8 years and weighing
at least 55 lb, perform automated external defibrillation with adult
electrodes
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Unresponsive infant or child who is younger than 8 years who weighs
less than 55 lb, perform automated external defibrillation with special
pediatric pads
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Unresponsive infant between the ages of 1 month and 1 year, use a
manual defibrillator. If a manual defibrillator is not available, an
automated external defibrillator (AED) equipped with a pediatric dose
attenuator may be used. If neither is available, an AED without a
pediatric dose attenuator may be used.
Follow local protocols to treat a patient in cardiac arrest. Ensure a patent airway, and
obtain an advanced airway as soon as possible. Establish IV access.
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Termination of efforts should be based on local protocol and direct communication
with online medical control.
The AED requires the operator to apply the pads, power on the unit, follow the AED
prompts, and press the Shock button if indicated. The computer inside the AED
recognizes rhythms that require shocking and will not mislead you.
The three most common errors in using certain AEDs are failure to keep a charged
battery in the machine, applying the AED to a patient who is moving, and applying
the AED to a responsive patient with a rapid heart rate.
Do not touch the patient while the AED is analyzing the heart rhythm or delivering
shocks.
Effective cardiopulmonary resuscitation (CPR) and early defibrillation with an AED
are critical interventions to the survival of a patient in cardiac arrest. If the patient is
in cardiac arrest, start CPR, beginning with chest compressions, and apply the AED
as soon as it is available.
If paramedics are responding to the scene, stay where you are and continue CPR and
defibrillation as needed. Do not wait for the paramedics to arrive to begin
defibrillation. If paramedics are not responding, begin transport if the patient regains
a pulse, if you have delivered 6 to 9 shocks, or if the AED gives three consecutive
messages (separated by 2 minutes of CPR) that no shock is advised. Follow your
local protocols regarding when it is appropriate to transport the patient.
If an unresponsive patient has a pulse but loses it during transport, you must stop the
vehicle, reanalyze the rhythm, and defibrillate again or begin CPR, as appropriate.
The chain of survival, which is the sequence of events that must happen for a patient
in cardiac arrest to have the best chance of survival, includes recognition of early
warning signs and immediate activation of EMS, immediate CPR by bystanders, early
defibrillation, early advanced care, and integrated post-arrest care. Seconds count at
every stage.