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Normal Heartbeat

Each heartbeat begins in a specialized area of the right atrium called the sinus node. The sinus
node starts each heartbeat by generating a small amount of electricity, which spreads into the
muscle cells of the atria. This causes these upper chambers to contract.
Next, the electrical activity moves into the junction between the atria and ventricles. (The
ventricles are the heart’s main pumping chambers.) This area is called the atrioventricular node
or A-V node. The A-V node acts as a relay station. It takes the signal coming from the atria,
delays it slightly, then passes it into the ventricles, which causes them to beat. When the
ventricles beat, they pump blood throughout the body. This creates a pulse that can be felt at
several places in the body.
The brain tells the sinus node how fast to beat; it can speed up during exercise or in times of
stress and slow down when resting or sleeping. A normal fast heartbeat is called sinus
tachycardia. Normal slow heartbeat is called sinus bradycardia.

Diagnosis

Arrhythmias are abnormalities of the heart rate and rhythm (sometimes felt as
palpitations). They can be divided into two broad categories: fast and slow heart rates. Some
cause few or minimal symptoms. Others produce more serious symptoms of lightheadedness,
dizziness and fainting.
Some patients with otherwise normal hearts can have abnormal electrical pathways in their
hearts that cause arrhythmias. Patients with underlying problems in the function and structure of
the heart are more prone to heart rhythm problems. As patients who’ve had successful heart
surgery live longer, doctors are diagnosing more heart rhythm abnormalities.
A heart rhythm abnormality is evaluated in ways much like those used to evaluate other health
problems. The history of your symptoms, including sensation of your heart beating fast,
dizziness and fainting are very important.
Your doctor can use several tests to diagnose an arrhythmia. The first is usually an
electrocardiogram (ECG or EKG). An ECG machine records your heart’s electrical activity. The
tracings can be recorded on paper or a computer disk. However, EKGs are only a brief
snapshot of your heart rhythm and may not detect the actual arrhythmia.

The tests used to diagnose arrhythmias include exercise testing, Holter monitoring, event
recorders and electrophysiologic studies.

Types of Heart Rhythm Abnormalities
Fast Heart Rhythms.

Types of Heart Rhythm Abnormalities

  1. Supraventricular Tachycardia (SVT)
    This is the most common type of abnormal tachycardia in young adults. The fast heart rate —
    often over 150 beats a minute — starts in the heart’s upper chambers or in the upper part of the
    electrical conduction system. Symptoms include palpitations, chest pains, upset stomach,
    decreased appetite, lightheadedness or weakness. Some people can learn techniques to slow
    down their heart rate. Straining, such as closing the nose and mouth and trying to breathe out,
    may work. This is known as a Valsalva maneuver. Once the rhythm returns to normal, proper
    therapy with drugs can usually prevent future episodes. Patients often need an EP study with
    radiofrequency ablation to cure the problem.
  1. Atrial Tachycardia (including flutter or fibrillation)
    Atrial tachycardia, sometimes called atrial flutter or atrial fibrillation, is a particular type of SVT.
    This is a fast heart rate that starts in the heart’s upper chambers and is conducted to the lower
    chambers. It’s common after surgery that involves the atria (upper chambers), especially the
    Mustard, Senning and Fontan operations and in conditions that cause the atria to enlarge (most
    commonly from leakage or blockage or the mitral or tricuspid valves inside the heart). Besides a
    fast heart rate, other symptoms are fatigue, dizziness, lightheadedness and fainting. It usually
    requires treatment with medications or radiofrequency ablation.

.

This is a fast heart rate that starts in the heart’s lower chambers. It usually results from serious
heart disease and often requires prompt or emergency treatment. Symptoms can be mild but
generally are severe. They include dizziness, lightheadedness and fainting. Treatment options
include medication, radiofrequency ablation and implanting a device (defibrillator) that shocks
the heart into a normal rhythm or surgery.

This is a fast heart rate that starts in the heart’s lower chambers. It usually results from serious
heart disease and often requires prompt or emergency treatment. Symptoms can be mild but
generally are severe. They include dizziness, lightheadedness and fainting. Treatment options
include medication, radiofrequency ablation and implanting a device (defibrillator) that shocks


the heart into a normal rhythm or surgery.

This is a fast heart rate that starts in the heart’s lower chambers. It usually results from serious
heart disease and often requires prompt or emergency treatment. Symptoms can be mild but
generally are severe. They include dizziness, lightheadedness and fainting. Treatment options
include medication, radiofrequency ablation and implanting a device (defibrillator) that shocks
the heart into a normal rhythm or surgery.

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