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Glossary of Terms
ablation – a therapeutic method in which a form of energy is used to physically destroy a small
section of damaged heart tissue that is a source of abnormal electrical activity causing or
contributing to some types of tachycardia (fast heartbeat).
American Heart Association (AHA) – an organization whose mission is to fight heart disease and
stroke. Additional information is available on the AHA website at www.americanheart.org.
antiarrhythmic medication – a group of drugs that helps control and slow heart rate by either
suppressing (slowing) the activity of tissue that is initiating electrical impulses too quickly in the
SA node, or by slowing the transmission of fast electrical impulses inside the heart.
Antiarrhythmics include several classes of drugs such as sodium channel blockers, beta-blockers,
potassium channel blockers, calcium channel blockers, adenosine, and digitalis (also called
digoxin and digitoxin).
anticoagulant – a drug that decreases the ability of the blood to clot, or coagulate; sometimes
called a blood thinner, although they do not actually thin the blood. They are used to treat certain
blood vessel, heart and lung conditions. They are also given to certain people at high risk for
forming blood clots, such as those with artificial heart valves or who have atrial fibrillation.
Anticoagulants do not dissolve clots but may prevent existing clots from becoming larger and
causing more serious problems, and are often prescribed to prevent first or recurrent heart attack
or stroke.
arrhythmia – a disturbance in the normal rate and rhythm of the heart.
atrial fibrillation – a disorder of heart rate and rhythm in which the heart’s two small, upper
chambers (atria) quiver rapidly and empty blood into the heart’s lower chambers (ventricles) in a
disorganized manner instead of beating effectively. Blood that isn’t pumped completely out of the
atria when the heart beats may pool and clot. If a piece of a clot enters the bloodstream, it may
lodge in the brain causing a stroke (ischemic stroke).
atrial flutter – very rapid beating of the heart's upper chambers (atria). This rhythm occurs most
often in people with heart diseases such as pericarditis, coronary artery disease and
cardiomyopathy. Atrial flutter is typically not a stable rhythm and often degenerates into atrial
fibrillation.
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atrium – one of the two upper chambers of the heart that receive blood from the veins and in turn
force it into the ventricles.
bradycardia – a heart rate of less than 60 beats per minute.
cardiac electrophysiologist – see electrophysiologist.
cardiologist – a specialist in the structure, function, and disorders of the heart.
congestive heart failure (CHF) – the state in which ineffective pumping of the heart results in a
buildup of fluid in the lungs and elsewhere in the body. It does not mean the heart has stopped
working altogether. Different diseases can cause the condition, including coronary artery disease,
heart attacks and diseased heart valves. Common warning signs and symptoms include: fatigue,
shortness of breath, and swelling or pain in the abdomen or lower limbs. Also referred to as heart
failure.
coronary artery bypass graft (CABG) – a heart surgery that creates new routes around narrowed
and blocked arteries, allowing sufficient blood flow to deliver oxygen and nutrients to the heart
muscles.
dyspnea – shortness of breath, difficult or labored breathing.
echocardiogram –a technique that uses a hand-held device (transducer) to send sound waves (like
sonar) into the chest to rebound from the heart's walls and valves. The recorded waves show the
shape, texture, and movement of the valves. They also show the size of the heart chambers and
how well they're working.
electrocardiogram (ECG or EKG) – measures the timing and duration of each electrical phase of
a heartbeat. During an ECG, sensors (electrodes) that can detect the electrical activity of the heart
are attached to the chest and sometimes to a person’s limbs.
electrophysiologist – cardiologists who have specialized training in the heart's electrical system.
They specialize in diagnosing and treating heart rhythm problems (arrhythmias) such as atrial
fibrillation.
event monitor – a device used by patients for 30 days to record the heart’s electrical activity.
fibrillation – fast, uncoordinated contractions of individual heart muscle fibers. The heart
chamber involved can’t contract all at once and pumps blood ineffectively, if at all.
heart block – when the normal electrical impulses that make the heart function properly become
impaired or don’t transmit while traveling from the upper to lower chambers of the heart.
heart rhythm – the coordinated rhythmic pattern of electrical activity and/or muscle contractions
in the heart.
Heart Rhythm Society (HRS) – an organization whose mission is to improve the care of patients
by promoting research, education and optimal health care policies and standards. Additional
information is available on the HRS website at www.hrsonline.org.
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hyper – prefix meaning “high.”
hypo – prefix meaning “low.”
Holter monitor – a portable ECG device that can be worn for 24-48 hours to record the heart's
activity.
long QT syndrome – an acquired or inherited condition, which may be triggered by one or a
combination of more than 50 commonly used drugs. These drugs affect the heart's electrical
function. On an electrocardiogram, the letter Q marks the point where an electrical impulse
signals the ventricles to contract. The letter T marks the point where the cells of the ventricles
have electrically recharged for the next heartbeat. When the QT interval is prolonged, ventricle
cells may not have recovered in time to properly conduct the next heartbeat. People with long QT
syndrome are prone to palpitations and fainting spells, and may have an increased risk of sudden
death.
mobile cardiac outpatient telemetry (MCOT) – a CardioNet service that allows doctors to capture
significant arrhythmic events or definitively verify that no arrhythmic event occurred over a
period of up to 21 days. Common applications include primary cardiac diagnostics, postprocedure monitoring, and drug titration for heart rate control medications.
palpitations – the sensation of the heart beating rapidly or irregularly.
premature contractions – defined as extra, early, or "skipped" beats. These beats are the most
frequent cause of irregular heart rhythms. They can start in the upper or lower chambers of the
heart.
presyncope – symptoms such as dizziness, nausea, stomachache, chest pain, shortness of breath,
or sweating that occur prior to a syncopal event.
sick sinus – a condition that occurs if the pacemaking sinus node isn't sending impulses properly.
The heart rate may be too slow, or it may speed up and slow down intermittently. If the sinus
node is functioning properly, sick sinus can be caused by an impulse block near the sinus node
slowing, disrupting, or completely blocking conduction.
sinus tachycardia – a harmless rhythm and a normal increase in heart rate that happens with fever,
excitement, and exercise. It does not require treatment, except in rare cases when an underlying
problem, such as anemia or hyperthyroidism, should be treated.
supraventricular tachycardia (SVT) – a broad term that includes many forms of arrhythmia
originating above the ventricles (supraventricular). This type of arrhythmia may also be called
paroxysmal supraventricular tachycardia (PSVT). SVTs usually cause a burst of rapid heartbeats
that begin and end suddenly and can last from seconds to hours. These often start when the
electrical impulse from a premature heartbeat begins to circle repeatedly through an extra
pathway. SVT may cause the heart to beat 160 to 200 times a minute. Although generally not lifethreatening in an otherwise normal heart, symptoms from the racing heart may feel quite strong.
These arrhythmias are common in young people.
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syncope – is temporary loss of consciousness, described as “fainting” or “passing out,” related to
insufficient blood flow to the brain.
tachycardia – a heart rate of more than 100 beats per minute.
telemetry – the science and technology of automatic measurement and transmission of data by
wire, radio, or other means from remote sources to receiving stations for recording and analysis.
vasodilator drugs – medications, such as nitroglycerin or nesiritide (Natrecor®), which cause
blood vessels to expand, thereby increasing blood flow.
ventricle – one of the two lower chambers of the heart.
ventricular tachycardia (VT) – VT is characterized by a very fast heart rate and is usually seen
with other serious heart disease. This condition can interfere with the heart's ability to pump
enough blood to the brain and other vital organs. VT usually requires prompt treatment, with
medication, radiofrequency ablation, or surgery. People with VT are often protected with an
implantable defibrillator. Because VT can lead to ventricular fibrillation (see below), it is
considered a serious condition that warrants aggressive monitoring and treatment.
ventricular fibrillation (VF) – sudden cardiac arrest or death, is caused by ventricular fibrillation,
an electrical circuitry problem. VF accounts for half of all cardiac deaths. Within seconds, an
individual loses consciousness and, without immediate emergency treatment, will die within
minutes. If treated in time, VT and VF can be converted into normal rhythm with electrical shock.
Estimates indicate that more than 70 percent of VF victims die before reaching the hospital.
Wolff-Parkinson-White syndrome (WPW) – a type of SVT is known as Wolff-Parkinson-White
syndrome (WPW). This arrhythmia is caused by an extra electrical pathway between the atria and
the ventricles. This pathway may allow electrical current to pass between the atria and the
ventricles without passing through the AV node, leading to short circuits and rapid heartbeats.
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Sources:
American Heart Association, (www.americanheart.org)
Heart Rhythm Society, (www.hrsonline.org)