Cardiac Electrophysiology Consultants of South Texas, P.A.

Medical Center Tower I
7950 Floyd Curl Drive
Suite 803
San Antonio, TX 78229
tel: 210-615-9500
fax: 210-615-9600
email: office at
Specializing in the compassionate care of people who suffer from abnormalities of the electrical system of the heart Current Insurance Plans: We accept most major commercial insurance plans. Please call for details.
Medicare: We have opted out of Medicare, and are happy to care for Medicare beneficiaries on an affordable cash basis. Note: Federal law prohibits signing the Federally-mandated opt-out contract with a Medicare beneficiary who is in an emergency situation.
No insurance? No problem! Consider our affordable Fee for service (direct pay).
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General information about the heart for patients, their family members, and concerned laymen

| A | B | C | D | E | F | G | H | I | J | K | L | M |
| N | O | P | Q | R | S | T | U | V | W | X | Y | Z |

Please let us know if you have corrections, additions, comments, or questions about the glossary.
- A -
   Accessory Pathway
     A congenital (but not necessarily hereditary) abnormality in the heart consisting of a tiny, extra muscle strand that connects the upper and lower chambers of the heart. In the normal heart, there is electrical insulation between the atria and the ventricles. The atrioventricular (AV) node penetrates this insulation, and is normally the only way for electrical activity (which makes the heart contract) to get from the body's natural pacemaker in the right atrium to the powerful ventricles.

Accessory pathways, because they provide additional ways for electricity to travel through the heart, create a condition in which electricity can travel in a circle: down the AV node and back up the pathway, or visa versa. Each time electricity travels such a circle, it generates a heart beat. Because it can travel rapidly, the heart can go quite fast. The resulting rhythm is called "atrioventricular reentrant tachycardia".

Accessory pathways can conduct in both directions or only in one direction. When they conduct from the atria to the ventricles, they cause a characteristic sign on the electrocardiogram called a "delta" wave. These pathways are called "manifest" pathways, because they can be detected on the electrocardiogram. When they conduct only from the ventricles to the atria, they are called "concealed". People who have concealed accessory pathways can have atrioventricular reentrant tachycardia, but do not have Wolff-Parkinson-White Syndrome (the criteria for which include a delta wave).

  Acute (adjective)
     With sudden onset or rapidly changing. Used in contrast to subacute, which implies longer duration or less rapid change, and to chronic, which implies indefinite duration or virtually no change. The time scale depends on the subject under discussion. An "acute" myocardial infarction lasts about a week. An attack of "acute" endocarditits lasts only a few days (in the survivors).
  Afterload Reducing Agents
     Medications that relax the arteries, into which the heart pumps, and thereby make it easier for the heart to pump. They are useful for treatment of hypertension, congestive heart failure, and regurgitation of the mitral and aortic valves. Also known as "vasodilators".
  Atrium (singular), Atria (plural)
     The upper chambers of the heart. These are weaker, "primer" pumps that push an additional bit of blood into the more powerful lower chambers of the heart. They are useful, but not necessary, for staying alive. The right atrium receives blood from the body and pushes it towards the lungs. The left atrium receives oxygen-rich blood from the lungs and pushes it towards the body.
- B -
     An abnormal but usually harmless rhythm characterized by occurrence of one premature ventricular complex (PVC) after each normal QRS complex. This rhythm usually does not progress to dangerous forms of fast ventricular rhythms. Note that in this rhythm, two PVCs never occur one right after the other.
     Slow heart rate. For adults, less than 60 beats per minute. The heart rate can be low for a variety of reasons.
- C -
     A method for stopping almost all types of fast heart rhythms. This method consists of applying a brief but powerful electrical field to the heart, and is commonly known as "shocking the heart". It works by bringing all parts of the heart to the same "level" electrically for a short period of time (measured in thousandths of a second). This interrupts all known types of fast heart rhythm. The heart muscle then lies dormant until its natural pacemaker tissue (or an artificial pacemaker) generate electrical activity that makes the heart muscle contract again. As you can see, cardioversion will not stop sinus tachycardia, which is the rhythm that occurs when the natural pacemaker tissue is firing rapidly!

Cardioversion is generally safe and effective, and is the therapy of first choice when the patient's life is in danger because of the fast heart rhythm. It can also be done electively (i.e., as a matter of choice) when the heart rhythm does not respond to medication or a trial of medication is not desirable for some reason.

  Congestive Heart Failure
     The term "congestive heart failure" includes two groups of symptoms that are all caused by an enlarged (dilated) heart that is not able to pump enough blood to meet the body's oxygen and blood flow needs.

One group of symptoms is caused by accumulation of fluid in the air spaces of the lungs, and includes shortness of breath, particularly with exercise or during sleep, and swelling of the feet and legs. Rarely, people develop coughing, nausea and/or swelling of the abdomen. This group of symptoms is called "backward failure" because excess fluid in the lungs is unable to empty into the enlarged heart.

Another group of symptoms is caused by insufficient flow of blood from the heart into the body, and consists predominantly of fatigue. Other symptoms include pain in the abdomen and nausea.

The same two groups of symptoms can occur in other heart diseases that interfere with the pumping of the blood by the heart, including fast and slow heart rhythms, the "restrictive" cardiomyopathies, and the "constrictive" pericardial diseases.

  Chronic (adjective)
     Persisting for a long time (adjective). Used in contrast to acute, which implies sudden onset or rapid change, and acute, which implies recent onset or somewhat rapid change. The time scale depends on the subject under discussion.
  Carotid sinus massage
     A method for stopping certain kinds of fast heart rhythm. We won't tell you how to do it because you can get hurt if it is done incorrectly or if you have disease in the carotid arteries that you didn't know about. Ask your doctor, who can decide whether it is safe for you.
- D -
     A medication that increases the force of contraction of the heart. Digoxin is one of several drugs in the "digitalis" class, which comes from the Foxglove plant. It is more widely used that the others because the time it takes to affect the heart and its duration of action are more favorable for most patients than other drugs in the class such as ouabain and digitoxin. It also slows conduction through the atrioventricular node, making it useful for rate control in atrial fibrillation and atrial flutter.
     A medication that increases the rate at which the kidneys allow water to leave the body. Normally, the kidneys filter blood so that virtually everything in the blood except the cells is on track to leave the body in the urine. Then, in a very efficient manner, the kidney plucks out everything that is useful to the body. This arrangement has the desirable effect of allowing dangerous substances to leave the body (since the kidney does not retrieve them). In some disease states, however, the kidney retains too much water. Diuretic medications help the kidney retain less water than it otherwise would. The effect on the is to increase the amount of urine passed per day, weight loss, and (hopefully) relief of symptoms.

There are many different medicines that have diuretic effects.

     The symptom of shortness of breath or difficulty in breathing. The cause of dyspnea determines when the person experiences it. Asthma, for example, causes dyspnea during its exacerbations. Congestive heart failure causes exercise-induced dyspnea, because the increased oxygen demand of exercise is not met by the diseased heart; and night-time dyspnea, because fluid that accumulates in the legs during the day, when the person is upright, drains into the heart at night, when the person is horizontal. In this latter situation, the extra fluid is not handled by the diseased heart and then accumulates in the lungs.
- E -
     Infection of one or more of the heart valves. This condition often damages the affected valve(s). Endocarditis can be caused by bacteria, fungi, or other causes. The rate of damage to the affected valve(s) may be rapid, occurring over days, or slower, occurring over weeks to months. The term "acute endocarditis" applies when rapid damage occurs. This is almost always due to certain types of bacteria, so the term "acute bacterial endocarditis" is used in these cases. The term "subacute endocarditis" applies when damage is less rapid.
     A specialist who has extensive training in the diagnosis and treatment of abnormal heart rhythms. Clinical cardiac electrophysiologists graduate medical school, complete full training in Internal Medicine and in Cardiology and Cardiovascular Diseases, then complete an additional one to two years of further training, and then pass a national examination administered by the American Board of Internal Medicine.
- I -
     Insufficient oxygen supply to body tissues, usually resulting from insufficient blood flow. May also occur if the need of the tissue for oxygen is markedly increased, as happens in athletes when they get "burning" in their muscles. Myocardial ischemia can lead to angina pectoris and myocardial infarction.
- M -
   Medical Student Syndrome
     Medical Student Syndrome is what happens when people first learn about diseases. It is characterized by on-going (chronic) fear that the student has, or will have, some horrible disease. This fear arises from the recognition that some bad diseases can strike healthy people without warning. We all know this, of course. What brings on the syndrome is the concentrated study of many bad diseases, one right after the other. The student begins to imagine that he or she will soon develop one or another, and often several, of the most awful diseases.

The syndrome usually subsides when the student realizes, often upon awakening or in the shower, the power of statistics. The odds of getting one horrible disease are really quite low. The odds of getting more than one are far lower than that. So, while anything is possible, none of the diseases is particularly likely. Once this is recognized, the symptoms of the syndrome usually disappear. Good luck!

- N -
   Neurocardiogenic Syncope
     Fainting that is currently thought to be due to a hyperactive reflex between the heart and the brain. Also known as the "simple faint," it occurs most commonly when a person is in the upright position and may be dehydrated (having skipped breakfast and then going to a hot room such as church). The loss of consciousness begins gradually, over seconds to minutes, so that the person usually has time to sit down or at least to cushion the fall. (By contrast, other types of faints occur abruptly, and people often injure themselves because they have no time to cushion the fall.) Often, the person with neurocardiogenic syncope notices nausea and sweatiness before losing consciousness.

Neurocardiogenic syncope is most accurately diagnosed with a "tilt table test" which, although not perfect, is the best available and is right about 70-90% of the time. Several medications reduce or eliminate the occurrence of fainting episodes. These include the beta blockers and some anticholinergic agents, as well as newer therapies wih serotonin upake inhibitors.

- O -
   Orthostatic Blood Pressure
     "Orthostasis" is the word that describes what happens when a person is standing up. "Orthostatic blood pressure changes" is the phrase that describes what happens to the blood pressure when a person stands up. This is a useful concept because the blood pressure usually falls a little bit when a person changes from the lying to the sitting and the sitting to the standing positions. In some cases, however, the blood presssure falls a lot so that the person feels faint. In these cases, the person is said to be "orthostatic" (which is a shorthand phrase).

"Orthostasis" (using the shorthand phrase, now) can cause symptoms in normal people when they rise rapidly from the squatting to the standing position. It can cause symptoms more easily in people whose nervous system doesn't adapt as rapidly as normal to the fall in blood pressure: the many risk factors include diabetes mellitus, certain neurologic disease, and certain medicine. Another important cause of orthostasis is dehydration, either from insufficient oral fluid intake or from fluid loss such as internal bleeding.

A test for clinically significant orthostasis is done in three stages. First, the person lies down for a few minutes, and the blood pressure and pulse are measured (and recorded). Both arms should be checked to make sure that the higher of the two pressures is recorded (if there is a difference). Then, the person sits up for a few minutes and the process is repeated. Finally, the person stands for at least five minutes, and a final measurement of blood pressure and pulse is made. The person is "orthostatic" if the pulse rises by 20-30 beats per minute or more or if the blood pressure falls by 30 mmHg or more. Young people with dehydration willl usually show a pulse rise. Older people with systemic diseases like diabetes will usually show a blood pressure fall without much of a pulse rise.

The treatment depends on the cause. For otherwise healthy people, the best advice is to stand up slowly! In other cases, see a doctor for advice.

- P -
     The awareness of the heart beat. Usually due to one of two types of rhythms: premature complexes and tachycardias. Premature complexes are usually perceived as a pause followed by a "thump", without any associated other symptoms. Tachycardias are usually perceived as a rapid heart beat or a "fluttering" in the chest, and may be accompanied by faintness, shortness of breath, or even loss of consciousness.
- Q -
     An abnormal but usually harmless rhythm characterized by occurrence of one premature ventricular complex (PVC) after every three normal QRS complexes. This rhythm usually does not progress to dangerous forms of fast ventricular rhythms. Note that in this rhythm, two PVCs never occur one right after the other.
- S -
  Subacute (adjective)
     Recent onset or somewhat rapid change. Used in contrast to acute, which implies sudden onset or rapid change, and acute, which implies indefinite duration or virtually no change. The time scale depends on the subject under discussion.
     Fainting spell, transient loss of consciousness. There are many causes of syncope. They can be divided into those caused by problems with the heart (cardiovascular), with the brain (neurological), and with other causes (such as bleeding and dehydration). Many cardiovascular and neurological problems can cause syncope. Evaluation by a competent health care professional is advisable in all cases in which a person loses consciousness even for a moment.
- T -
     Fast heart rate. Usually, greater than 100 beats per minute. For some rhythms such as ventricular tachycardia, a somewhat higher heart rate of 120 beats per minute is used as a cutoff. The heart rate can be high for a variety of reasons.
     A blood clot, when it forms inside the body.
   Thrombolytic Drugs
     "Clot buster" medicine. It actively dissolves thrombus. By contrast, heparin and the antiplatelet drugs (aspirin, ticlcid, Rheopro, etc.) inhibit formation of new thrombus, but do not destroy old thrombus. Remember that the body has its own thrombolytic system that also dissolves thrombus.
   Thrombolytic System
     The cascade of clotting factors that break down thrombus. See your friendly hematology textbook for details.
     An abnormal but usually harmless rhythm characterized by occurrence of one premature ventricular complex (PVC) after every two normal QRS complexes. This rhythm usually does not progress to dangerous forms of fast ventricular rhythms. Note that in this rhythm, two PVCs never occur one right after the other.
- V -
  Valsalva Maneuver
     A method for stopping certain fast heart rhythms. Done with common sense, it is safe and often effective. We recommend that you have your doctor show you how to do it. If you need to do it on an emergency basis (at your own risk, mind you), the procedure is as follows:
  1. lie down, preferably with your feet raised about a foot or so.
  2. put your hand on your tummy (over the middle of the abdomen, for you good 'ol boys).
  3. press your hand in on your tummy lightly, then tighten your belly muscles so that you resist the pressure of your hand.
  4. now press your hand harder until you feel your throat close up a bit. You may also feel your bottom tighten up as if you are "bearing down" during a bowel movement. Keep up this pressure for about 10 seconds.
  5. remove your hand from your belly and release the tension in your belly muscles quickly.
  6. if the maneuver works, the heart rhythm should stop within about 5 seconds.
  7. you can repeat this maneuver somewhat more forcefully and with a longer period of pressure up to about 30 seconds, if the rhythm persists. But remember that this technique sometimes doesn't work.
The principle of the maneuver is that when you have pressure in your belly (abdomen), the blood in the your legs can't return to your heart because the veins through which it returns are compressed by the pressure. When you release the pressure suddenly, all that blood rushes in the heart which, by reflex, pushes it all out quickly. That raises the blood pressure slightly, which causes the brain to increase the "vagal tone". The vagal tone is a signal to the heart to slow down. One of the ways that vagal tone makes the heart slow down is to slow conduction through the atrioventricular (AV) node. When conduction slows through the AV node, rhythm that travel through the AV node (atrioventricular nodal reentrant tachycardia and atrioventricular tachycardia) often stop. Aren't you glad you asked?
  Ventricle (singular), Ventricles (plural)
     The lower chambers of the heart. These are stronger, "power" pumps that push blood into the lungs and into the body. They receive blood from the atria. The right ventricle is useful, but not always necessary, for staying alive. The left ventricle is necessary to sustain life, although it can keep a person alive and relatively well even if it has been severely (but not critically) damaged. The right ventricle receives blood from the right atrium and pushes it into the lungs. The left ventricle receives oxygen-rich blood from the left atrium and pushes it into the body. The pumping capacity of the left ventricle is one of the major factors that determine the blood pressure.
- W -
  Wolff-Parkinson-White Syndrome
     Wolff-Parkinson-White Syndrome is the combination of an accessory pathway that conducts from the atria to the ventricles (creating a "delta" wave on the electrocardiogram) and the occurrence of two types of fast heart rhythms (tachycardias), atrioventricular reentrant tachycardia and/or atrial fibrillation. These tachycardias can cause serious symptoms. However, people who have Wolff-Parkinson-White Syndrome but who do not have any symptoms of tachycardias do not appear to be otherwise at risk.

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