Fast Heartbeat in the Lower Heart

Background Image

In most healthy people, a normal heart rate is 60 to 100 beats per minute. A heart rate faster than 100 beats a minute is called tachycardia.

Get Prepared For Discussions with Your Doctor

Get Prepared

For Discussions with Your Doctor

Share Your Feedback Via a Brief Survey

Share Your Feedback 

Via a Brief Survey


To help you understand tachycardia, it helps to understand your heart's electrical system.The heart’s pumping action is driven by electrical stimulation within the heart muscle. The heart’s electrical system allows it to beat in an organized pattern. Electrical signals in your heart can become blocked or irregular, causing a disruption in your heart’s normal rhythm. When your heart beats out of rhythm, it may not deliver enough blood to your body.

Sometimes a rate above 100 beats is normal. For example, when you are exercising, your body needs more oxygen and so your heart rate rises to meet this demand. Other times, a fast heartbeat greater than 100 beats a minute is not normal and is the result of a problem with the heart or irregular electrical signals in the heart. If you have a fast heart rate, it could be caused by a type of tachycardia.

These types of arrhythmias are categorized by where they originate:

  • In the atria (the upper chambers of the heart)
  • In the ventricles (the lower chambers of the heart)

Tachycardias that originate in the ventricles—or the lower chambers of the heart—are:

Ventricular Tachycardia

Ventricular tachycardia, also called VT, occurs when abnormal electrical impulses start in the lower chambers of the heart (the ventricles) causing the heart to beat too quickly. With this disorder, the heart doesn't fill with enough blood between beats to meet the body's needs.

Sometimes, ventricular tachycardia lasts for 30 seconds or less and is harmless. However, these episodes may put you at risk for more serious ventricular arrhythmias. A sustained episode of VT (more than 30 seconds) is a medical emergency as it can quickly become ventricular fibrillation. Ventricular fibrillation is a life-threatening arrhythmia demanding immediate treatment with either an external defibrillator or an implantable cardioverter defibrillator (ICD).

What Are the Symptoms?

Following are symptoms of ventricular tachycardia:

  • Palpitations, rapid thumping or a pounding sensation in your chest
  • Fatigue or light-headedness
  • Fainting
  • Shortness of breath
  • Chest pain

What Are the Causes?

Causes of ventricular fibrillation include:

  • Coronary artery disease
  • Heart attack
  • Diabetes
  • High cholesterol
  • High blood pressure
  • Cigarette smoking
  • Drug or alcohol abuse
  • High fat diet
  • Sedentary lifestyle
  • Stress
  • Certain medications (over-the-counter and prescriptions, including decongestants and diet and herbal supplements)
  • Heart surgery
  • Family history of heart disease
  • Congenital heart disorders (heart problems present at birth, usually involving the heart's chambers or valves)
  • Advancing age
  • Gender (males are more susceptible)

Animation

    Recommended animation:
  • Fast Heartbeat Arrhythmias: Ventricular Tachycardia

View Understanding Arrhythmias and Treatment Options Animations 

Ventricular Fibrillation

Ventricular fibrillation (VF) occurs when rapid, chaotic electrical impulses cause the lower chambers of the heart (the ventricles) to quiver rather than pump blood. Ventricular fibrillation can occur spontaneously (generally caused by heart disease) or when ventricular tachycardia has persisted too long. When the ventricles fibrillate, they do not contract normally, so they cannot effectively pump blood. The instant VF begins, effective blood pumping stops. Most often, VF leads to sudden cardiac arrest.

What Are the Symptoms?

The first, and usually only, symptom associated with ventricular fibrillation is a sudden loss of consciousness due to inadequate blood supply to the brain.

What Are the Causes?

Possible causes of VF include:

  • Heart attack
  • Heart failure
  • Heart surgery
  • Coronary artery disease
  • Diabetes
  • High cholesterol
  • High blood pressure
  • Cigarette smoking
  • Drug or alcohol abuse
  • Excess weight
  • High fat diet
  • Sedentary lifestyle
  • Stress
  • Certain medications (over-the-counter and prescriptions, including decongestants and diet and herbal supplements)
  • Family history of heart disease
  • Congenital heart disorders (heart problems present at birth, usually involving the heart's chambers or valves)
  • Advancing age

Animation

    Recommended animation:
  • Fast Heartbeat Arrhythmias: Ventricular Fibrillation

View Understanding Arrhythmias and Treatment Options Animations

Long QT Syndrome

Long QT syndrome (LQTS) is a rare, and sometimes fatal, heart rhythm disorder that results from abnormalities in the heart's electrical recharging system (the area that causes it to beat). It is characterized by fast, chaotic heartbeats that may lead to fainting or, in some instances, sudden death. It often is present from birth. (The QT in the name refers to the measure of time between the start of the Q wave and the end of the T wave in the heart's electrical cycle.)

What Are the Symptoms?

Many people with LQTS do not have signs or symptoms. Those who do may experience fainting, seizure or sudden cardiac death.

Symptoms may occur:

  • During physical activity or emotional upset
  • After being startled by sudden noises such as sirens or alarm clocks
  • During sleep or upon waking up

What Are the Causes?

Inherited LQTS is caused by genetic factors. These genes control the production of certain types of ion channels in your heart. The genes may result in your body making too few ion channels, ion channels that do not work properly or both.

Acquired LQTS may be caused by certain medicines or other medical conditions. Currently, more than 50 medications have been recognized to cause LQTS. Some of these medicines include:

  • Antihistamines and decongestants
  • Diuretics
  • Antibiotics
  • Antidepressants
  • Cholesterol-lowering medicines and some diabetes medicines
  • Too much diarrhea or vomiting that causes a major loss of potassium or sodium ions may cause LQTS until the levels of these ions in the blood return to normal. Also, anorexia nervosa and certain thyroid disorders may cause a drop in potassium ion levels in the blood, leading to LQTS.

Animation

    Recommended animation:
  • Fast Heartbeat Arrhythmias: Long QT Syndrome

View Understanding Arrhythmias and Treatment Options Animations