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Ablation Surgery (Catheter Ablation
Surgery)
In this procedure, one or more flexible, thin tubes (catheters) are introduced
under X-ray guidance into the blood vessels and directed to the heart
muscle. A burst of radio frequency energy destroys very small areas of
tissue that give rise to abnormal electrical signals.
AED
See External Defibrillator.
Antiarrhythmic Drugs
Medication designed to prevent or treat cardiac arrhythmias.
Arrhythmia
An irregular heartbeat. This could be a rhythm that's abnormally slow
(bradycardia) or a rhythm that's too fast (tachycardia). See also bradycardia
and tachycardia.
Atherosclerosis
See Coronary Artery Disease.
Atria
Plural for atrium. See Atrium.
Atrial Fibrillation
Extremely rapid, irregular atrial impulses. This rapid rate does not allow
the atria to pump blood effectively into the ventricles. It can also cause
irregular rapid ventricular beats.
Atrial Flutter
A cardiac arrhythmia in which the atrial contractions are rapid (230-380
per minute), but regular.
Atrioventricular Node (AV node or
AV junction)
Electrical signals from the sinoatrial (SA) node travel from the atria
through the AV node before moving to the ventricles. The AV node helps
keep the upper and lower heart chambers beating in synchrony. When the
AV node is blocked, it can result in a slow heartbeat called heart block.
An artificial pacemaker can take over an impaired AV node to restore a
more normal heart rate.
Atrium
The heart is divided into four chambers. The upper chambers are called
atria, the lower chambers are called ventricles. The atria receive blood
from the veins and pump the blood to the ventricles through the tricuspid
(right) or mitral (left) valve.
Automatic External Defibrillator
(AED)
See External Defibrillator.
Bradycardia
A condition in which the heart beats at less than 60 beats per minute.
This heart rate may be too slow or irregular to meet the body's demands.
(This is different than a physically fit person who may have a heart rate
below 60.)
Cardiac Catheterisation
Cardiac catheterisation (also called cardiac cath or coronary angiogram)
is a procedure that allows the doctor to "see" how well your
heart is functioning. The test involves inserting a long, narrow tube
called a catheter into a blood vessel in your arm or leg, and guiding
it to your heart with the aid of a special X-ray machine. Contrast dye
is injected through the catheter so that X-ray movies of your valves,
coronary arteries and heart chambers can be created.
Cardiologist
Physician specially trained in the diagnosis and treatment of heart disease.
Cardiomyopathy
Cardiomyopathy is a disease of the heart muscle. The heart loses its ability
to pump blood and, in some instances, heart rhythm is disturbed, leading
to irregular heartbeats, or arrhythmias. Usually, the exact cause of the
muscle damage is never found.
Cardiopulmonary Resuscitation
(CPR). The mechanical pushing of the heart (hands pushing on rib cage)
and breathing (through the mouth) done in a rhythmic pattern. These actions
keep blood and oxygen circulating through the body. CPR is often used
as a first emergency response until an external defibrillator can be applied
to restart the heart.
Cardioversion
An implantable cardioverter defibrillator (ICD) therapy used to treat
rapid heart rhythms. Cardioversion consists of shock impulses that may
progress from low-energy to high-energy levels, depending on the therapy
needed to stop the rapid rhythm.
Cardiovascular
Nurse
Works in a hospital area where patients with arrhythmias and other heart
problems are monitored.
Cardiovascular Technician
Assists doctors with cardiovascular procedures and surgeries.
Catheter (cath lab; electrophysiology, or EP)
lab nurse/technician
Participates in electrophysiology studies and surgeries for pacemakers
and implantable cardioverter-defibrillators (ICDs).
Chemotherapy drugs
Certain drugs used in chemotherapy may weaken the heart muscle and result
in low ejection fraction and heart failure.
Coronary artery disease (CAD)
One of the most common causes for heart failure. Hardening of the coronary
arteries leads to a blockage of blood flow, resulting in a weakening of
the heart muscle. Obstructed coronary arteries also cause heart attacks,
damaging the affected portion of the heart muscle.
Conduction Pathway
Pathways that conduct electrical impulses to the atria through the atrioventricular
(AV) node and around the ventricles, thereby causing the heart to beat
and pump blood throughout the body.
Defibrillation
An ICD therapy option used to treat ventricular fibrillation. Defibrillation
consists of high-energy shock impulses.
Defibrillator
See ICD.
Diagnostic Test
This is a test that is ordered by a physician to determine or rule out
a condition.
Dyssynchrony
A condition in which the two lower chambers of the heart are not beating
together as they do normally. In a normal heart, both sides beat together
and are effectively "synchronised."
Echocardiogram
(echo)
A type of ultrasound test that uses high-pitched sound waves to produce
an image of the heart. An echocardiogram is used to evaluate how well
the heart chambers fill with blood and pump blood to the rest of the body
with each heartbeat (called the ejection fraction).
Echocardiologist
A cardiologist who performs cardio-vascular examinations using echocardiograms
to produce a picture of a heart and great vessels using high-frequency
sound waves.
Ejection fraction (EF)
A measurement of how much blood (what fraction or percentage of blood)
the pumping chambers of the heart (the left and right ventricles) are
able to pump out, or eject, and supply to the organs (brain, kidneys,
liver, etc.) and muscles of your body.
Electrocardiogram (ECG)
A recording of the heart's activity.
Electrophysiologist
A cardiologist with a specialisation in the diagnosis and treatment of
arrhythmias. Electrophysiologists are experts in the electrical function
of the heart.
Electrophysiology (EP) study
A study used to evaluate the electrical system of the heart.
Exercise ECG
See Stress Test.
External Defibrillation
An electric shock given to the heart through paddles placed on the chest
in order to restart the electrical system of the heart. External defibrillation
may be done using a manual external defibrillator or an automated external
defibrillator (AED).
External Defibrillator (AED)
Portable devices used to electrically stimulate a fibrillating heart.
Using an external defibrillator, strong electric shocks are passed between
paddles and electrodes placed on a patient's chest.
External Loop Recorder
A device that monitors heart rhythm and rate for up to one month. During
this test, the patient wears a device on the wrist or around the waist.
When symptoms are experienced, the patient presses a button on the device
to make a recording of the heart activity that just occurred.
Heart
Attack or Myocardial Infarction
When the heart muscle is damaged because blood is blocked from reaching
it, a heart attack occurs. A heart attack is also called a myocardial
infarction (MI) because the middle layer of the heart muscle (myocardium)
is damaged or is non-functional (infarct).
Heart's Electrical System
The heart has its own electrical system. Special tissues conduct electrical
signals that travel along pathways through the heart to stimulate the
heart to beat, that is, the contractions of the heart's chambers pump
the blood throughout the heart and into the body.
Heart Failure
Heart failure occurs when your heart muscle doesn't pump as much blood
as the body needs. "Failure" doesn't mean that the heart has
stopped pumping, just that it is failing to pump as effectively as it
should. Heart failure is most often caused by a problem with the left
ventricle of the heart.
Heart Rhythm Specialist
See Electrophysiologist.
Heart Rhythm Team
A team of doctors, nurses, technician and other healthcare professionals
who provide care for your heart condition and other medical conditions.
Heart Valve Disease
Valves within the human heart that open and close automatically to control
the flow of blood into, through, and out of the heart. These valves open
to ensure that blood flows into the heart chambers as needed, and they
close to ensure that blood does not flow back into the heart after it
has been pumped out to the lungs and body.
Heavy alcohol use
If alcohol is used excessively over an extended period, it has a toxic
effect on the heart muscle.
High blood pressure (hypertension)
Uncontrolled high blood pressure causes the heart to work extra hard to
pump blood through the body. A constantly overworked heart ultimately
progresses to heart failure.
Holter Monitor
A device that measures and records heart rhythm over 1-3 days. This test
may be done when an ECG does not show the arrhythmia and it still is suspected
to be the cause of symptoms. Patches with wires are placed on the chest.
The wires are connected to a portable monitor that can be attached to
a purse or belt.
Implantable (Cardioverter) Defibrillator
(ICD)
An ICD is a small device placed inside the body that treats abnormally
rapid heart rhythms. It can deliver several types of therapies, including
cardioversion, defibrillation, and anti-tachycardia pacing. An ICD is
usually implanted in the upper chest or in the abdominal area.
Insertable Loop Recorder
A device that continuously monitors the heart rhythm for up
to 14 months. This small device is placed under the skin during a short
procedure using a local anaesthetic. When a symptom is experienced, the
patient places a hand-held activator over the recorder. Later, a physician
analyses the stored information.
Leads
A thin insulated wire with electrodes (electrical contacts) located near
the tip.
Long-Term Support Pacing
Therapy
Sometimes after a shock is delivered, the heart rate may be too slow.
If that happens, or if there is any other reason the heart may slow down,
the defibrillator sends pacing pulses, like a pacemaker, that raise the
heart rate back to normal.
Manual External
Defibrillator
Portable devices used to electrically stimulate a fibrillating heart.
Using an external defibrillator, strong electric shocks are passed between
paddles and electrodes placed on a patient's chest.
Multiple Gated Acquisition Test (MUGA)
A small dose of radioactive material is injected intravenously into the
bloodstream. A scanning device then reveals how much blood the heart is
able to eject out of both the left and right ventricles.
Myocardial Infarction (MI or heart attack)
After one or several heart attacks, scar tissue prevents the heart from
working efficiently, leading to a weakening and dilating of the heart
chambers (left and right ventricle) and frequently progressing to heart
failure. See Heart Attack.
Myocarditis (inflammation of the heart muscle)
Myocarditis is most often caused by a viral infection, leaving the heart
muscle damaged.
Nuclear Scan
For this test, a radioactive substance is injected during exercise. Then
a special image is taken of the heart, to see how well blood is flowing
through the heart.
Pacemaker
A pacemaker system is a two-part electrical system that includes a pulse
generator (pacemaker) and one or two leads, or wires, which deliver impulses
to the heart. The leads also carry signals back from the heart. By "reading"
these signals, the pulse generator is able to monitor the heart's activity
and respond appropriately. A pacemaker helps to pace the heart when the
natural rate is too slow (bradycardia) to pump enough blood to the body.
Pacing
The defibrillator may send pacing pulses when the heartbeat is just a
little too fast. When several pacing pulses occur rapidly, they usually
won't be felt. The patient may feel lightheaded or dizzy because of the
rapid heartbeat.
Programmer
A small computer used at the follow-up clinic to check the pacemaker.
The programmer header is often placed over the pacemaker to collect information
stored in the pacemaker.
Radionuclide Angiogram
(RNA) Test
See Multiple Gated Acquisition Test (MUGA).
Risk Assessment Quiz
A quiz designed to assess a person's risk for Sudden Cardiac Arrest.
Sinoatrial Node (SA node)
A group of cells located in the right atrium that sends out electrical
signals which make the heart pump. The SA node is the heart's natural
pacemaker. These signals travel from the SA node, through the atrioventricular
(AV) node, and then to the rest of the heart. The SA node also responds
to the need for a faster heart rate. If a person is exercising or excited,
the body will require greater blood circulation. A healthy SA node responds
to these changes in the body and increases the heart rate accordingly.
Sinus Node (SA node)
See Sinoatrial Node.
Stress Test
Reveals how well the heart functions during exercise.
Sudden Cardiac Arrest (SCA)
Sudden cardiac arrest is when the heart's lower chambers (ventricles)
suddenly develop a rapid, irregular rhythm (ventricular fibrillation)
and the quivering ventricles cannot pump blood to the body. Within seconds,
the person will not have a pulse and will be unconscious. Without immediate
treatment, the person almost always dies. Sudden cardiac arrest is not
a heart attack. Heart attack is a problem with the plumbing of the heart;
one or more of the arteries delivering blood to the heart is blocked.
Oxygen in the blood cannot reach the heart muscle and the heart muscle
is damaged.
Sudden Cardiac Death (SCD)
Natural death due to cardiac causes, noted by abrupt loss of consciousness
within an hour of the onset of acute symptoms. Preexisting heart disease
may or may not have been known to be present, but the time and mode of
death are unexpected.
Supraventricular Tachycardia (SVT)
A fast arrhythmia (over 100 beats per minute) that originates an electrical
impulse at the top of the heart. There are many types of SVTs, each named
for the generator of the abnormal heart rhythm.
Sustained Fast Heart Rhythms (tachycardia)
Tachycardias such as atrial fibrillation (AF) sustained over an extended
period may result in low ejection fraction and a damaged heart muscle.
Syncope
A temporary loss of consciousness due to lack of blood to the main portion
of the brain (the cerebrum).
Tachycardia
A category of heart rhythm disorders (arrhythmias) characterised by an
abnormally rapid or irregular heart rhythm. Known causes of tachyarrhythmias
include coronary artery disease, heart attack and heart muscle disease.
Tachyarrhythmia
See Tachycardia.
Tilt Table Test
This procedure attempts to simulate conditions that may cause arrhythmia.
It enables a physician to understand how blood pressure, heart rate and
rhythm respond to a change in position from lying down to standing. The
patient is positioned on a table, given medication, and the table is tilted
by varying degrees. The test typically lasts for a couple of hours.
Valvular
Heart Disease
One of the heart's four valves (two aortic, two mitral) may be narrowing
(stenosis) or leaking, restricting blood flow to the heart. In certain
cases, valvular endocarditis (infection of the heart valves) may cause
damage to the valves, impairing blood flow.
Ventricle
One of the two lower chambers of the heart. The right ventricle pumps
blood to the lungs. The left ventricle pumps blood to the body's organs.
Ventricular Fibrillation (VF)
A heart rhythm disorder that originates in the ventricles. It is characterised
by an abnormally rapid heart rhythm that is also highly unstable and irregular.
During VF, electrical signals are moving chaotically through the heart,
preventing it from beating properly. This often results in fainting. If
left untreated, it may result in cardiac arrest.
Ventricular Tachycardia (VT)
A heart rhythm disorder that originates in the lower chambers. VT is characterised
by a rapid heart rhythm during which patients may feel faint or dizzy,
or even collapse. During VT, the heart does not pump blood as efficiently
as it does during a normal rhythm, and rapid contractions prevent it from
filling adequately with blood between beats. VT can be dangerous, life-threatening,
if not properly treated.
Last updated: 20 January 2005
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