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).

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.

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.

There are many different medicines that have diuretic effects.

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!

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.

"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.

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.