What is Ventricular Tachycardia?
Ventricular tachycardia is an abnormal heart rhythm where the ventricles beat quickly, but evenly. This is similar to ventricular fibrillation, but the ventricles beat quickly and unevenly. The term tachycardia refers to a fast heart rate.
Ventricular tachycardia may develop as a complication of a heart attack because scar tissue can form in the ventricle muscle within days, months, and or years after a heart attack. Additionally, it can occur in patients with cardiomyopathy, heart failure, heart surgery, myocarditis, and valvular heart disease.
In ventricular tachycardia abnormal electrical signals originate in the ventricles, instead of the normal pathway from the atria down to the ventricles. If left untreated, ventricular tachycardia may lead to a dangerous and life-threatening ventricular fibrillation.
Both of these arrhythmias impair blood flow out of the heart (cardiac output) and are both medical emergencies.
Animation of Ventricular Tachycardia
How does ventricular tachycardia occur?
Sometimes the electrical impulses ‘short circuit’ and travel across the heart in an abnormal way. Abnormal electrical pathways produce irregular heartbeats and rhythms known as arrhythmias. Arrhythmias occur when other areas of the heart, other than the SA node, begin sending out their own impulses and take over the pacemaker function of the SA node. The sites that take over could be from any area of the atria, AV node, or ventricles, in this case the ventricles.
The rapid rate does not allow the complete filling of the ventricles to pump blood out to the entire body. Symptoms of ventricular tachycardia such as lightheadedness or dizziness may be felt.
How is it classified?
Ventricular tachycardia can be classified in several ways.
Based on the morphology: (shape of the beats on EKG)
Monomorphic ventricular tachycardia: all the beats appear to match each other on an electrocardiogram (EKG). i.e. right ventricular outflow tract (RVOT)
Polymorphic ventricular tachycardia: beat to beat variability seen on an EKG. i.e. torsades de pointes (“twisting of the points”)
By the duration of the episode:
Non-sustained ventricular tachycardia- a fast heart rhythm which terminates within 30 seconds
Sustained ventricular tachycardia- a fast heart rhythm that lasts for more than 30 seconds
On the basis of symptoms:
Pulseless ventricular tachycardia- no effective cardiac output and no effective pulse, causing cardiac arrest. Pulseless VT requires defibrillation.
Idiopathic ventricular tachycardia- occurs in younger individuals; cause of ventricular tachycardia is unknown, but presumed to be due to congenital causes
What are the causes?
Ventricular tachycardia can be due to abnormalities or diseases of the heart, or by diseases elsewhere in the body affecting the heart. Ventricular tachycardia may occur after open heart surgery, substance abuse, or medications.
Heart abnormalities and diseases include:
- Congenital heart defects (heart defect from birth)
- Coronary artery disease (decreased blood supply to the heart) or atherosclerosis
- High blood pressure
- Heart attack
- Cardiomyopathy and congestive heart failure
- Rheumatic fever and pericarditis (inflammation of the heart)
- Abnormalities of the heart valves, especially mitral stenosis and mitral regurgitation
- Hypertrophy (enlarged heart)
Diseases elsewhere in the body affecting the heart:
- Pulmonary embolism (blood clot in lung)
- Chronic obstructive pulmonary disease (COPD) and emphysema
- Sleep apnea
- Electrolyte imbalances (low potassium/ magnesium levels)
- Consuming large amounts of alcohol (binge drinking)
- Cocaine, amphetamines, diet pills, caffeine, or cold medicines
- Carbon monoxide intoxication
First week following open heart surgery
Who is at risk?
The following are at risk of developing ventricular tachycardia:
- Increasing age
- Family history of ventricular tachycardia
- Drinking alcohol or binge drinking
- Use of recreational drugs
- Electrolyte imbalances
- Heavy caffeine use
- Heart failure patients and COPD patients
- Pericarditis (inflammation of the heart) and autoimmune diseases
- Other chronic conditions including thyroid disorders and sleep apnea
What are the symptoms?
Symptoms of ventricular tachycardia occur because the heart rate is beating so fast, blood pressure falls; therefore the heart can not pump enough oxygen rich blood to the body causing symptoms. Some patients may be unaware of their heart beating abnormally. Although characteristic symptoms include:
- Shortness of breath
- Sensation of neck fullness
- Rapid pulse rate
- Chest pain (angina)
- Fainting (syncope)
- Intolerance to exercise
- Swelling of the legs or abdomen
What are the complications?
The complications of ventricular tachycardia include:
- Syncope (fainting)
- Heart failure
- Thrombus (clot formation)
- Sudden cardiac arrest
When should I seek medical care?
If you experience symptoms of ventricular tachycardia, call your physician.
If you faint, have difficulty in breathing, or have chest pain lasting more than a few minutes, call emergency care or call 911. These are urgent symptoms of a potentially fatal ventricular tachycardia and must seek emergency care immediately to avoid the risk of cardiac arrest and death.
How is it diagnosed?
The diagnosis of ventricular tachycardia will be based on your history, physical examination, and certain tests.
1. Patient history
Most patients will give a history of characteristic symptoms like palpitations, dizziness, fatigue, shortness of breath, etc.
2. Physical Examination
You will be examined for signs of ventricular tachycardia including:
Weak or no pulse
Low blood pressure
Varying heart sounds heard over chest
Certain tests can be performed to determine the cause and severity of your condition including:
- Blood tests- to check potassium, magnesium, and thyroid hormone levels
- Electrocardiogram- this is a very useful and simple test that records the electrical activity of the heart and reveals ventricular tachycardia. Also shows signs of heart attack, conduction abnormalities, hypertrophy, and electrolyte imbalances.
- Chest X-ray- a simple test performed in our office showing the size and shape of the heart may also reveal the presence of fluid in the lungs.
- Echocardiogram (ECHO) – a noninvasive test performed in our office to determine the size and function of the heart’s chambers and the structure and function of the heart valves.
- 24-Hour Holter monitor- records the electrical events of the heart during your normal daily activities. This is useful in detecting evidence of arrhythmias.
- Event monitor- If symptoms of arrhythmia are infrequent and do not occur within 24 hours, an event recorder may be ordered for you for up to 30 days.
- Stress test- determines how well the heart works during exercise.
How is it treated?
The treatment goals for tachycardias are to slow a fast heart rate when it occurs, prevent future episodes, minimize complications, and treat the underlying cause.
1. Stop a fast heart rate:
A fast heart rate may terminate spontaneously, or you may be able to slow your heart rate using simple physical methods.
Medications and procedures may be required in addition to these methods.
- Vagal maneuvers: this maneuver can be done during an episode of a fast heart beat. This includes coughing or bearing down as if having a bowel movement.
- Medications: anti-arrhythmic medication can be used to restore a normal heart rate. These medications include flecainide or propafenone.
- Cardioversion: if a pulse is present, a shock is delivered to your heart through pads attached to the chest wall. The current interrupts the electrical impulses in the heart and restores a normal rhythm.
2. Preventing episodes of tachycardia:
- Catheter ablation: is a hospital procedure done to destroy areas on the heart that are causing irregular heart rhythms. A thin flexible tube is inserted into a blood vessel to access the heart. Heat is applied to the tip of the catheter to permanently destroy small areas of abnormal heart tissue. The damaged tissue is no longer capable of generating electrical impulses. A pacemaker may be placed after this procedure
- Medications: anti-arrhythmic medications may prevent tachycardia, when taken regularly. These medications include: calcium channel blockers such as diltiazem and verapamil or beta blockers such as metoprolol and esmolol or anti-arrhythmic such as lidocaine and amidarone.
- Pacemaker or ICD- a small implantable device used to regulate the heart rate and rhythm. Therefore, the heart contracts in a regular way. An ICD shocks the heart out of the dangerous rhythm.
3. Treating the underlying disease:
Treatment of an underlying condition attributing to tachycardia such as some form of heart disease or hyperthyroidism may prevent or minimize tachycardic episodes.
How can I prevent this?
Ventricular tachycardia can not always be prevented, but there are ways of reducing the risk of developing ventricular tachycardia.
Leading a healthy lifestyle may reduce the chance of coronary artery disease, which can cause ventricular tachycardia.
Some ways you can do this is by:
- No smoking!
- Drink in moderation
- Limit caffeine
- Avoid recreational drugs
- Be physically active. Engage in moderate physical activity for at least 30 minutes a day
- Eat nutritious foods low in cholesterol and fats
- Maintain a BMI below 25
- Control high blood pressure, cholesterol, and sugar
- Control stress
- Have regular physical exams and report any signs or symptoms to your physician