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Ventricular tachycardia may last only for a few seconds but can also last for minutes at a time, in which case it can be life-threatening
Ventricular tachycardia is a heart rhythm disorder that is caused by abnormal electrical signals in the lower chambers of the heart.
Also called VT or V-tach, ventricular tachycardia may last only for a few seconds but can also last for minutes at a time, in which case it can be life-threatening. In some cases it can cause sudden cardiac arrest, which is a serious medical emergency.
What is ventricular tachycardia?
A healthy heart normally beats around 60-100 times a minute at rest. However, with VT, the heart beats at least 3 times faster, which is more than 100 beats a minute.
The heartbeat is controlled by electrical signals that begin at the sinoatrial (SA) node (the heart’s natural pacemaker) and go on to follow a signaling pattern along a fixed pathway. The signaling causes the atria (upper chambers of the heart) to contract, allowing blood to flow down to the ventricles (lower chambers of the heart). The ventricles are then signaled to contract and allow the blood to move along.
In VT, abnormal electrical signaling in the ventricles causes the heart to beat abnormally fast (rates of 170 beats a minute or more). This prevents the heart chambers from filling up with blood properly. Subsequently, the heart is unable to pump sufficient blood to other parts of the body, which can lead to health problems and life-threatening complications.
What causes ventricular tachycardia?
Ventricular tachycardia caused by a disruption in the normal electrical signaling that heart rate and is produced in two ways:
- Reentry: Abnormal heart circuit inside the ventricular muscle that is triggered.
- Automaticity: Abnormal ventricular muscle that becomes self-activated.
VT can also occur in a normal healthy heart, caused by some sort of damage or scar from an accident or previous coronary illness.
Elderly people and those with a family history of heart problems are more at risk of developing VT. However, some other conditions that can cause VT or increase the risk include:
- Damage from previous heart diseases, such as a myocardial infarct, heart failure, heart valve disease, or myocarditis (inflammation of the heart muscle)
- Sarcoidosis, a condition that causes inflammation of tissues in the body
- Conditions passed down from your parents, such as long QT syndrome or Brugada syndrome
- Side effects from antibiotics, antimalarials, or thyroid hormones
- Abnormal levels of electrolytes in the blood
- Heavy use of alcohol or caffeine
- Recreational drugs, such as cocaine and methamphetamine
What are the risk factors of ventricular tachycardia?
Any condition or illness that puts strain on the heart or causes damage to the heart tissue can cause abnormal signaling and increase the risk of ventricular tachycardia. You may be more at risk of ventricular tachycardia you have:
- Structural abnormality in heart valves
- Cardiomyopathy
- Heart failure
- Coronary artery disease
- Heart attack
Hereditary disorders that can increase the risk of VT include:
- Conditions such as hypertrophic cardiomyopathy, which cause abnormal heart muscle
- Diseases that affect the heart muscle, such as sarcoidosis
- Diseases that cause changes in the heart rhythm itself, such as long QT syndrome or Brugada syndrome
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What are the signs and symptoms of ventricular tachycardia?
Brief episodes of VT may not cause any symptoms and can be difficult to notice. In other cases, VT can cause symptoms such as:
- Fast heartbeat or a fluttering feeling in the chest (palpitations)
- Dizziness
- Shortness of breath
- Lightheadedness
- Tightness in the neck
Sustained and severe episodes of ventricular tachycardia may cause:
How is ventricular tachycardia diagnosed?
Your doctor will review your medical history and symptoms and perform a physical examination. Tests ordered to confirm a diagnosis include:
- Electrocardiogram (ECG): Records the heart pace and rhythm.
- Holter monitor or event recorder: Portable ECG device that is carried in your pocket or worn as a belt or strap and records cardiac activity for a period of time (hours to weeks), allowing the doctor to monitor the heart more closely.
- Telemetry: Continuous monitoring of the heart.
- Stress monitoring: Stress tests or monitoring can help detect a problem in the heart.
Your doctor may order test images of the heart to determine whether any structural problems are affecting the blood flow and causing ventricular tachycardia. Cardiac imaging tests used include
- Echocardiogram: Creates a moving picture of the heart using sound waves.
- Magnetic resonance imaging (MRI): Provides still or moving pictures of how the blood is flowing through the heart.
- Computed tomography (CT): Combines several X-ray images to provide a more detailed cross-sectional view of the heart.
- Coronary angiogram: Studies the flow of blood through the heart and blood vessels and may reveal potential blockages or abnormalities.
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How is ventricular tachycardia treated?
The goals of VT treatment are to reestablish a normal heart rhythm, control the fast pulse when it occurs, and prevent future episodes of tachycardia.
Treatment depends on what is causing the arrhythmia and the type or severity of VT. No treatment may be required if there is no underlying coronary illness, no serious symptoms, or the VT episodes do not last for long.
Treatment options may include:
- Cardioversion: Electric shock is used to reestablish the heart’s regular rhythm. This is an emergency treatment that is used if VT occurs alongside fainting or low blood pressure.
- Medications: Medications may be prescribed to help slow the pulse. They include Nexterone, Pacerone (amiodarone), Tambocor (flecainide), Lidopen (lidocaine), Rythmol SR (propafenone) or Betapace, and Sotylize (sotalol).
- Cardiac resynchronization treatment (CRT): A pacemaker is implanted close to the collarbone, which sends signals to the ventricles to make sure they function normally.
- Implantable cardioverter–defibrillator (ICD): A device is implanted under the skin just beneath the collarbone, which sends a shock to reset the pulse if it is uneven.
- Cardiac ablation: Heat is used to destroy abnormal heart tissue, which prevents abnormal signals from conducting through the heart.
