Patients Resources/Glossary

Ablation. A catheter-based, minimally invasive procedure to destroy the "nerve" or "nerves" in the heart that cause rapid heartbeat.  Click this link for more detailed discussion.

Accessory Pathway.  An extra pathway that causes rapid heart beat.  It is the cause for the WPW syndrome.

AICD.  This abbreviation stands for Automatic Implantable Cardioverter Defibrillator.

AF, AFib.  These are common abbreviations for Atrial fibrillation.

Arrhythmia. A general term to describe irregular heartbeat. It is synonymous with the layman's term "irregular heartbeat."

Atrial fibrillation.  A rapid and irregular heartbeat that originates in the upper chambers of the heart, the atria.  See link for more discussion.

Atrio-ventricular Node (AV node). A nerve bundle in the middle part of the heart which processes and relays signal from the upper chamber (atrium) to the lower chamber (ventricle). This relay station is important in that the atrium acts as a "pacemaker" for your heart, generating signals for heart beat. This signal must be transmitted to the ventricle for one to have a heartbeat. If the AV node does not function, then we may have a condition of heart block and slow heartbeat.  See this link for a brief description of normal physiology of the heart.

Atrium. The upper chambers of the heart, of which there is the right and the left atrium. These chambers' main function is to collect blood and transport to the ventricles for the ventricle to eject blood for circulation. The atrium is important in several ways.  It contains the sinus node, the main pacemaker of the heart that generates every heartbeat.  It is also a source of irregular heartbeat, such as atrial fibrillation, atrial flutter, and SVT.  See this link for a brief description of normal physiology of the heart.

AV Block.  A conduction block that occurs at the Atrial-Ventricular level.  This applies to the electrical function of the heart, not related to any blockage in the artery.

AVNRT.  Atrioventricular Nodal Reentrant Tachycardia, rapid rhythm originating near the AV node.

BiV, Biventricular.  This is a surgery to implant an extra lead (wire) in the left ventricle for "Cardiac Resynchronization Therapy" for the treatment of heart failure.  See also "Cardiac Resynchronization Therapy" below.

Bradycardia. In English, it simply means slow heartbeat. (See section on heart block).

Bundle Branch Block.  This refers to the electrical conduction defect in one of the two cables of the heart, the right bundle and the left bundle.  See also RBBB and LBBB.

Cardiac Electrophysiology.  See Electrophysiology.

Cardiac Resynchronization Therapy (CRT). This is a new form of surgery that "resynchronizes" a failing heart.  In many patients with heart failure, the heart is enlarged and the ventricles do not beat in a synchronous, or organized, fashion. Standard pacemakers and defibrillators utilize two wires for pacing. CRT devices takes advantage of a third wire that allows simultaneous pacing of the right and the left ventricles. This therapy, surgery for which requires specialized training and expertise, has been shown to improve patients with heart failure.

Cardioversion.  This procedure restores normal rhythm of the heart by delivering a quick shock through the chest.

Defibrillator (internal defibrillator, ICD, AICD). A defibrillator is a pacemaker that is also capable of shocking the heart. A pacemaker, on the other hand, only paces the heart and does not shock the heart. The reason to implant a defibrillator is that a patient may have a rapid, irregular, and life threatening arrhythmia.  It will shock the heart at the very instant that the heart goes into this rhythm.

Echocardiogram, Echo.  This is a non-invasive, ultrasonic picture of the heart.

Ejection Fraction (EF). This is a measure of how well, or how poorly, the heart is beating. It measures the amount of blood that is ejected with each heartbeat relative to the total amount of blood in the heart before the ejection. Having an ejection fraction of 50% means the heart squeezes 50% of its volume with each heart beat (normal EF is 50-70%).  This number is one of the most important measurements in cardiology and electrophysiology. Patients with a very low ejection fraction (<35%) are often candidates for an implantable defibrillator (ICD or AICD).

EKG, ECG.  Electrocardiogram, or Electrocardiograph, is a basic recording of your heart rhythm.

Electrophysiology and ElectrophysiologistElectrophysiology is the study of electrical disturbances of the heart. An Electrophysiologist is a Cardiologist with added certification in Electrophysiology. He or she generally has gone through 7-8 years of specialized training after graduating from medical school to be in this field.

Electrophysiology study. This procedure is performed by inserting one or several catheters from the veins in the groin or in the neck and into the heart. Electrical stimulation is then applied to the heart to investigate its electrical properties and uncover arrhythmias. This procedure is performed by an Electrophysiologist.

EMR.  Electronic Medical Record.  Records are kept in the computer rather than on paper, thus the name "paperless."

Event Monitor.  This is a "patient-triggered" outpatient long-term (30 days) recording of heart rhythm.  See this link for detail.

Fibrillation. This is a very rapid and irregular, chaotic rhythm. It can occur either in the atrium or the ventricle. The rate is often so fast (> 300 beats per minute) such that it renders the chamber involved paralyzed and pulseless.  Fibrillation in the atrium (atrial fibrillation) can cause many symptoms and the complication of stroke.   Fibrillation In the ventricle (ventricular fibrillation) is immediately fatal.

Holter.  This is a 24-hour continuous recording of your heart rhythm.  See this link for detail.

Heart Block.  This refers to a "block" in the electrical conduction of the heart, not the artery.

Heart Failure.  This is a general term referring to a syndrome where patient experiences shortness of breath and reduced activity tolerance due to afailing heart.

His Bundle.  This is an important structure connecting the upper chamber (atrium) with the lower chamber (ventricle) of the heart, without which there is heart block and heart stops.  See normal anatomy and physiology.

ICD.   This abbreviation stands for "Implantable Cardioverter-Defibrillator."  It is used interchangeably with "AICD" or "Defibrillator."

Implantable Loop Recorder.  This is a tracking device implanted under the skin to diagnose difficult-to-find arrhythmias.

Implantable Pacemaker.  This term is usually synonymous with the term "Pacemaker."  An implantable pacemaker is permanently implanted in the patient.  The term "implantable" distinguishes this from an "external" pacemaker.  It is also referred to as a "permanent" pacemaker because it is permanently implanted, as opposed to the "temporary" pacemaker which are applied externally or internally on a temporary basis.

Implantable Defibrillator.  A permanently implanted defibrillator, it is synonymous with the terms "ICD" or "AICD."

INR.  This stands for "Internal Ratio," which is a standardized measurement of how "thin" or "thick" the blood is in patients taking blood thinner like coumadin.  The higher the number, the thinner the blood, the easier for bleeding.  The lower the number, the thicker the blood, the higher chance for blood clot.

Mapping.  This is a term used to describe the diagnostic part of Electrophysiology Study where the source of the arrhythmia is "mapped" out using catheters placed within the heart chambers.  Please see this link.

Mapping, 3-D.  This is a specialized mapping technique which utilizes a computer to delineate the source of complex arrhythmias.  It does so by projecting a virtual 3-demensional image of the heart onto the computer.  This virtual reality helps the physician navigate within the heart, very much like what GPS does for driving.  Please see this link.

Left Bundle Branch Block (LBBB).  This refers to a delayed or defective conduction in the "left bundle" of the heart.  See this link.

Long QT Syndrome (LQTS).  This is a genetic, or inheritable, abnormal rhythm condition that results in prolonged "QT" interval on the EKG.  Patients can have symptoms of fainting and even sudden cardiac arrest.

P Wave.  This is the first part of the EKG cycle, generated by the atrium, or the top part of the heart.  See normal anatomy and physiology.

Pacemaker. This is an electronic device that paces the heart. The primary indication for a pacemaker today is to treat slow heartbeat (bradycardia, heart block).  A pacemaker can be "implantable" or "external."  It can be permanent or temporary.  A permanent one is inserted under the skin and is connected via one, two, or three wires that go into the inside of the heart via the veins (transvenous).  See also "Implantable Pacemaker."

Percutaneous.  This adjective refers to a procedure that is done "through the skin."  As the body is entirely covered by the skin, in reality all invasive procedures are done "through the skin."  However, In medicine, a "percutaneous" procedure refers to one that is performed by inserting small catheters through the skin via the veins or the arteries, to gain access to the heart.  This is distinguished from the "open-heart" procedure that is done by opening up the chest to gain access through the heart.  For example, an angioplasty is a "percutaneous" procedure whereas coronary bypass surgery is an "open heart procedure."  Essentially all Electrophysiology procedures are minimally invasive, percutaneous procedures.

Pro-Time, Pro-Thrombin Time, PT.  This is synonymous with INR.

R Wave.  This is the part of the EKG that is generated by the ventricles, or the lower chambers of the heart.

Radiofrequency Ablation.  A cardiac ablation procedure that utilizes radiofrequency energy.  This accounts for over 97% of all cardiac ablations.

Right Bundle Branch Block (RBBB).  his refers to a delayed or defective conduction in the "right bundle" of the heart.  See this link.

QRS.  The part of the EKG that is generated by the ventricles, or the lower chambers of the heart.  An "R wave" is a component of a "QRS."

Sick Sinus Syndrome (SSS).  This is a syndrome where the heart fails to beat on a regular basis.  It is often too slow to sustained normal daily activity and may need treatment with a pacemaker.

Stress Test.  This is a test which usually involves some form of "stress" on the heart (by treadmill or sometimes by medications) in order to uncover any underlying heart conditions.

Sudden Cardiac Death/Sudden Cardiac Arrest.  This is a lethal conditions that causes rapid demise of the patient if not immediately treated.

Supraventricular Tachycardia (SVT).  An arrhythmia which originates above the ventricle (thus, "supraventricular" tachycardia), this condition is due to an "extra nerve" in the heart.  The majority of SVTs can be treated with medications or cured with ablation.

Syncope.  In English, the word syncope means "fainting."  It does not imply any etiology, of which there are many.

Tachycardia. In English, tachycardia simply means the heartbeat is fast. This term does not distinguish the origins of the rhythm abnormality.  It is a very general term that means nothing more than that the heart is fast. One must qualify by saying what kind of tachycardia it is, e.g., atrial tachycardia, or ventricular tachycardia.

Tilt Table.  This test helps the physician identify the cause of fainting spell.  See here for detail.

Transvenous.  This terms means "through the vein."  A "transvenous" procedure is one that is done through the vein, as opposed to a "open heart" surgery.

Ventricle. The bottom chambers of the heart, of which there is the right and the left ventricle. The ventricles take the blood from the atria and pump it out of the heart into circulations in the lungs and in the body. The ventricles are the main pumping chambers of the heart.

Ventricular Tachycardia (VT).  A serious and life-threatening arrhythmia originating in the ventricles, this condition can cause palpitation, lightheadedness, fainting, and even cardiac arrest.

Wolff-Parkinson-White Syndrome (WPW).   This is a syndrome involving an extra nerve in the heart that connects between the atrium and the ventricle.  See this link for more discussion.