Tachycardia


Tachycardia

Description, Causes and Risk Factors:

Heart is made up of four chambers — two upper chambers (atria) and two lower chambers (ventricles). The rhythm of heart is normally controlled by a natural pacemaker — the sinus node — located in the right atrium. The sinus node produces electrical impulses that normally start each heartbeat.

From the sinus node, electrical impulses travel across the atria, causing the atria muscles to contract and pump blood into the ventricles. The electrical impulses then arrive at a cluster of cells called the atrioventricular node (AV node) — usually the only pathway for signals to travel from the atria to the ventricles.

The AV node slows down the electrical signal before sending it to the ventricles. This slight delay allows the ventricles to fill with blood. When electrical impulses reach the muscles of the ventricles, they contract, causing them to pump blood either to the lungs or to the rest of the body.

Tachycardia is a fast or irregular heart rhythm, usually more than 100 beats per minute and as many as 400 beats per minute. At these elevated rates, the heart is not able to efficiently pump oxygen-rich blood to your body.

Tachycardia can occur in either the upper heart chambers (atrial tachycardia) or lower heart chambers (ventricular tachycardia). Tachycardia is caused by something that disrupts the normal electrical impulses that control the rhythm of your heart's pumping action. Many things can cause or contribute to problems with the heart's electrical system, which may include:

    Heart-related conditions such as high blood pressure (hypertension).

  • Poor blood supply to the heart muscle due to coronary artery disease (atherosclerosis), heart valve disease, heart failure, heart muscle disease (cardiomyopathy), tumors, or infections.

  • Other medical conditions such as thyroid disease, certain lung diseases, electrolyte imbalance, and alcohol or drug abuse.

  • Emotional stress or drinking large amounts of alcoholic or caffeinated beverages.

  • Smoking.

  • Side effects of medications.

  • Coronary artery disease (atherosclerosis).

  • Heart failure (poor pumping heart).

  • Heart attack (myocardial infarction).

  • Congenital heart defects (condition you are born with).

  • Inflammatory or degenerative heart conditions.

  • Chronic lung disease.

Other Risk factors may include:

    Old age.

  • Family history.

Symptoms:

Symptoms of tachycardia include:

    Shortness of breath.

  • Dizziness.

  • Sudden weakness.

  • Fluttering in the chest.

  • Lightheadedness.

  • Fainting.

Diagnosis:

Your doctor can make a diagnosis of a specific tachycardia based on your answers to questions about symptoms, a physical exam and heart tests.

Common tests include the following.

    Holter monitor: This portable ECG device is carried in your pocket or worn on a belt or shoulder strap. It records your heart's activity for an entire 24-hour period, which provides your doctor with a prolonged look at your heart rhythms. Your doctor will likely ask you to keep a diary during the same 24 hours. You'll describe any symptoms you experience and record the time they occur.

  • Electrocardiogram (ECG): An electrocardiogram — also called an ECG or EKG — is a primary tool for diagnosing tachycardia. An ECG uses small sensors (electrodes) attached to your chest and arms to record electrical signals as they travel through your heart. Your doctor can look for patterns among these signals to determine what kind of tachycardia you have and how abnormalities in the heart may be contributing to a fast heart rate.Your doctor may also ask you to use portable ECG devices at home to provide more information about your heart rate. These devices include:

  • Event recorder: This portable ECG device is intended to monitor your heart activity over a few weeks to a few months. You activate it only when you experience symptoms of a fast heart rate. When you feel symptoms, you push a button, and an ECG strip of the preceding few minutes and following few minutes is recorded. This permits your doctor to determine your heart rhythm at the time of your symptoms.

  • Electrophysiological test: Your doctor may recommend an electrophysiological test to confirm the diagnosis or to pinpoint the location of problems in your heart's circuitry. During this test, thin, flexible tubes (catheters) tipped with electrodes are threaded through your blood vessels to various spots in your heart. Once in place, the electrodes can precisely map the spread of electrical impulses during each beat and identify abnormalities in your circuitry.

  • Tilt table test: This test helps your doctor better understand how your tachycardia contributes to fainting spells. Under careful monitoring, you'll receive a medication that causes a tachycardia episode. You lie flat on a special table, and then the table is tilted as if you were standing up. Your doctor observes how your heart and nervous system respond to these changes in position.

  • Additional tests: Your cardiologist may order additional tests to diagnose an underlying condition that is contributing to tachycardia and judge the condition of your heart.

Treatment:

There are several treatment options available for people who experience tachycardia. Tachycardia can be ventricular (in the lower chambers of the heart) or atrial (in the upper chambers of the heart). Your cardiologist will determine the treatment that's best for your condition.

Ways to slow your heartbeat include:

    If medical condition is contributing to tachycardia — for example, some form of heart disease or hyperthyroidism — treating the underlying problem may prevent or minimize tachycardia episodes.

  • Vagal maneuvers. Your doctor may ask you to perform an action, called a vagal maneuver, during an episode of a fast heartbeat. Vagal maneuvers affect the vagus nerve, which helps regulate your heartbeat. The maneuvers include coughing, bearing down as if you're having a bowel movement, and putting an icepack on your face.

  • Medications. If vagal maneuvers don't stop the fast heartbeat, you may need an injection of an anti-arrhythmic medication to restore a normal heart rate. An injection of this drug is administered at a hospital. Your doctor may also prescribe a pill version of an anti-arrhythmic drug, such as flecainide (Tambocor) or propafenone (Rythmol), to take if you have an episode of a fast heartbeat that doesn't respond to vagal maneuvers.

  • Cardioversion. In this procedure, a shock is delivered to your heart through paddles or patches on your chest. The current affects the electrical impulses in your heart and restores a normal rhythm. It's typically used when emergency care is needed or when maneuvers and medications aren't effective.

  • Implantable cardioverter-defibrillator. If you're at risk of having a life-threatening tachycardia episode, your doctor may recommend an implantable cardioverter-defibrillator (ICD). The device, about the size of a cell phone, is surgically implanted in your chest. The ICD continuously monitors your heartbeat, detects an increase in heart rate and delivers precisely calibrated electrical shocks to restore a normal heart rhythm.

  • Surgery. Open-heart surgery may be needed in some cases to destroy an extra electrical pathway. In another type of surgery, called the maze procedure, a surgeon makes small incisions in heart tissue to create a pattern or maze of scar tissue. Because scar tissue doesn't conduct electricity, it interferes with stray electrical impulses that cause some types of tachycardia. Surgery is usually used only when other treatment options don't work or when surgery is needed to treat another heart disorder.

Preventive Measures:

    Exercise and eat a healthy diet.

  • Maintain a healthy weight.

  • Keep blood pressure and cholesterol levels under control.

  • Stop smoking, if you smoke.

  • Drink in moderation.

  • Don't use recreational drugs.

  • Use over-the-counter medications with caution.

  • Limit caffeine.

  • Control stress.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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