FYI = Warning it's long

• by heartu
• 2010-05-06 08:05:18
• Conditions, Meds & Tests
• 1429 views
• 3 comments

I have been reading a nymber of posts in which arguments ensue regarding what are arrhythmias and what tests should be perfomed based on symptoms. I have found this info on the American Heart Association site, which or any layperson can understand. Only an ECG/EKG can determine if a person has an arrhythmia. A qualified doctor can read and interpret an ECG as to what is going on with the heart's electrical system.

http://www.americanheart.org/presenter.jhtml?identifier=3

Electrocardiography (ECG)
An arrhythmia is considered documented if it can be recorded on an electrocardiogram (ECG or EKG.) This is the standard clinical tool for diagnosing arrhythmias. It records the relative timing of atrial and ventricular electrical events. It can be used to measure how long it takes for impulses to travel through the atria (the heart's upper chambers), the atrioventricular (AV) conduction system and the ventricles (the heart's two lower, pumping chambers). Because of the fleeting nature of arrhythmias, a person who complains of symptoms that suggest arrhythmia may often have an ECG that appears normal. Electrocardiographic techniques are passive; they can only record an arrhythmia if it occurs spontaneously while the ECG is being taken.

To conduct an ECG, the healthcare professional places small patches or stickers called electrodes on different parts of the body. One is put on each arm and leg and several across the chest. They don't hurt. With various combinations of these electrodes, different tracings of the heart's electrical activity can be made and permanently recorded on paper or in a computer.

Three major waves of electric signals appear on the ECG. Each one shows a different part of the heartbeat.

The first wave is called the P wave. It records the electrical activity of the atria (the heart’s upper chambers).
The second and largest wave, the QRS wave, records the electrical activity of the ventricles (the heart’s lower chambers).
The third wave is the T wave. It records the heart's return to the resting state.
Doctors study the shape and size of the waves, the time between waves and the rate and regularity of beating. This tells a lot about the heart and its rhythm.


Holter monitor (continuous ambulatory electrocardiographic monitor)
Suspected arrhythmias sometimes may be documented by using a small, portable ECG recorder, called a Holter monitor (or continuous ambulatory electrocardiographic monitor). This can record 24 hours of continuous electrocardiographic signals. While an ECG is sort of a 12-second "snapshot" of the heart's electrical activity, the Holter monitor is more like a "movie."

As with an ECG, electrodes are taped to the chest. The wires are connected to a portable, battery-operated recorder that can run for 24 to 48 hours. You can do most normal activities while being tested. You may need to keep a diary or log of your activities and symptoms.

At the end of the measurement period, the recorder’s tape or memory is analyzed on a computer that rapidly identifies rhythm disturbances that occurred while you were wearing the monitor. The diary helps your healthcare professional see how your activities or symptoms correspond to recorded events in your heart.

For suspected arrhythmias that occur less frequently than every day, your doctor might have you wear an event monitor.


Transtelephonic monitor (or event recorder)
Sometimes arrhythmia symptoms happen infrequently or pass so quickly that you can't get to a doctor or hospital. In these cases, a transient event monitor may be used. This small recorder is sent home with you for a month or two. When you have symptoms, attach the recorder with bracelets, finger clips or patches under the arms. The ECG will be recorded and stored. When it's convenient, you can transmit the ECG by phone to your cardiologist to be analyzed.


Treadmill testing
This is an option that provokes arrhythmias and makes their diagnosis (and thus their proper treatment) easier. A treadmill test may be used for people whose suspected arrhythmias are clearly exercise-related. It is important to know if exercise makes an arrhythmia worse. To test this, you will walk and run on a treadmill — or ride a stationary bicycle — while your heart rate and rhythm are monitored.



Tilt table studies
A tilt test may be advised for some people who've had recurrent fainting spells (syncope). This test shows how your heart rate and blood pressure respond to a change in position from lying down to standing up. In this test, an intravenous line (a small plastic tube in a vein) is usually started in case medications need to be given during the test. A catheter also may be placed in the artery to monitor blood pressure from inside the artery. If a cause of the fainting spells is found, medications can be given through the intravenous line to help prevent the episodes.



Electrophysiologic testing
This method has become extremely valuable for provoking known but infrequent arrhythmias and for unmasking suspected arrhythmias. This procedure is done using local anesthesia. Temporary electrode catheters are placed through peripheral veins (or arteries) into the heart using a fluoroscope. Then these catheters are positioned in the atria, ventricles or both, and at strategic locations along the conduction system. They record cardiac electrical signals and "map" the spread of electrical impulses during each beat, thus showing where the heart block is (AV node vs. His-Purkinje system). This test also shows where tachycardia originates (supraventricular vs. ventricular) far better than an ECG usually does.

The ability to electrically stimulate the heart at programmed rates and induce precisely timed premature beats lets a doctor assess electrical properties of the heart's conduction system. Most significantly, it also triggers latent tachycardia or bradycardia. Induced tachycardias can usually be stopped by rapid pacing via the electrode catheters. Sometimes an externally applied shock may be required if the patient loses consciousness during the tachycardia. Being able to "turn on" and "turn off" tachycardias during electrophysiologic studies allows antiarrhythmic drugs to be tested quickly for effectiveness. This can be done during a single study using intravenous therapy or during short follow-up studies with oral medication. Electrophysiologic testing has been performed safely worldwide; complications only rarely occur.



Esophageal electrophysiologic procedure
In some situations, your cardiologist may advise doing an esophageal electrophysiologic procedure. This is used to diagnose or treat the type of tachycardia you have. A thin, soft, flexible plastic tube will be inserted into your nostril and positioned in the esophagus (the tube that connects the mouth and stomach). Because the esophagus is close to the heart's upper chambers (atria), an ECG recording there gives more precise information than a regular ECG. An electrical stimulator may be used to make the heart beat faster to try to restart your arrhythmia. This helps your doctor make the right diagnosis.

During this procedure certain medications may be tested to find the most effective one. This procedure also may be done to temporarily stop certain types of arrhythmias.



Transthoracic echocardiography (TTE)
An echocardiogram uses ultrasound waves to map a picture of the heart, much like sonar is used to study solid objects in the sea. You may only think of ultrasound being used to monitor a baby's growth, but ultrasound waves can also show the heart's size, structure and motion. A technician has you turn on your left side. The technician places some gel on your chest and then moves a transducer over your chest and obtains images of your beating heart. It's a non-invasive test that's simple, painless and often provides valuable information about a heart with an arrhythmia.


This link identifies the causesof arrhythmias :

http://www.americanheart.org/presenter.jhtml?identifier=15

Causes and Symptoms of Arrhythmias

Causes

Normally, the heart's most rapidly firing cells are in the sinus (or sinoatrial or SA) node, making that area a natural pacemaker.

Under some conditions almost all heart tissue can start an impulse of the type that can generate a heartbeat. Cells in the heart's conduction system can fire automatically and start electrical activity. This activity can interrupt the normal order of the heart's pumping activity.

Secondary pacemakers elsewhere in the heart provide a "back-up" rhythm when the sinus node doesn't work properly or when impulses are blocked somewhere in the conduction system.
An arrhythmia occurs when:

The heart's natural pacemaker develops an abnormal rate or rhythm.
The normal conduction pathway is interrupted.
Another part of the heart takes over as pacemaker.
Symptoms
Arrhythmias can produce a broad range of symptoms, from barely perceptible to cardiovascular collapse and death.

A single premature beat may be felt as a "palpitation" or "skipped beat."

Premature beats that occur often or in rapid succession may cause a greater awareness of heart palpitations or a "fluttering" sensation in the chest or neck.
When arrhythmias last long enough to affect how well the heart works, more serious symptoms may develop:

Fatigue
Dizziness
Lightheadedness
Fainting or near-fainting spells
Rapid heartbeat or pounding
Shortness of breath
Chest pain
In extreme cases, collapse and sudden cardiac arrest




And finally this link identifies treatment goals for those with diagnosed heart arrhythmias:

http://www.americanheart.org/presenter.jhtml?identifier=559

Do you need treatment?
Most arrhythmias are considered harmless and are left untreated. Once your doctor has documented that you have an arrhythmia, he or she will need to find out whether it’s abnormal or merely reflects the heart’s normal processes. He or she will also determine whether your arrhythmia is clinically significant – that is, whether it causes symptoms or puts you at risk for more serious arrhythmias or complications of arrhythmias in the future. If your arrhythmia is abnormal and clinically significant, your doctor will set a treatment plan.

Treatment goals:

Prevent blood clots from forming to reduce stroke risk
Control your heart rate within a relatively normal range
Restore a normal heart rhythm, if possible
Treat heart disease/condition that may be causing arrhythmia
Reduce other risk factors for heart disease and stroke