At rest, a healthy heart beats around 60 to 100 times per minute. When the heartbeat rises to more than a hundred per minute, it is known as tachycardia. A higher heart rate, coupled with conduction problems, can lead to improper filling and improper blood flow within the heart. This can reduce the ability of the heart to pump enough blood for the whole body. When this happens, you may feel lightheaded or lose consciousness.

Ventricular arrhythmias may occur even in a structurally sound heart. A minor abnormality in the electrical system of the bottom chambers of the heart can cause the heart to go out of rhythm. Ventricular tachycardia is a serious medical emergency characterized by a rapid heart rate that can lead to sudden cardiac arrest if not treated promptly. 

What are the symptoms of ventricular tachycardia?

The most common symptoms and signs of ventricular tachycardia occur due to the heart's pumping inefficiency and its inability to supply enough blood and oxygen to the whole body. Some of these include:

• Weakness or dizziness
• Feeling your heart pounding
• Feeling lightheaded
• Feeling short of breath
• Pain in your chest

Ventricular tachycardia can be divided into two types based on how long it lasts. These are ‘nonsustained’ ventricular tachycardia that lasts less than 30 seconds and resolves independently. Such brief episodes may not always cause symptoms. If ventricular tachycardia lasts more than 30 seconds, this is known as ‘sustained’ ventricular tachycardia. It can lead to ventricular fibrillation and sudden death. This is a severe condition and requires treatment.

 What is the difference between ventricular tachycardia and ventricular fibrillation?

Although both conditions do have an abnormality with the heart rhythm, ventricular fibrillation is considered a more severe condition. In ventricular tachycardia, the heart muscles still function correctly, although they may not receive ample time to fill appropriately before they contract. However, in ventricular fibrillation, your muscles are not contracting correctly and are twitching instead. This means that they are not pumping blood into your body. This can lead to sudden death.

What causes ventricular tachycardia?

Your heart rate is usually controlled by electrical impulses that trigger the contraction of your heart muscles. When something happens to the conduction of the signals, and they get sent too quickly to the ventricles, tachycardia occurs. When the heart rate is high, the ventricles do not get time to dilate or relax properly. Although it may be hard to determine the exact cause of ventricular tachycardia, some conditions have been known to cause the symptoms. 

These include:

• Diseases that affect the structure of the heart, such as previous infection, Heart Attack, or a congenital abnormality
• Heart failure
• Coronary artery disease
• Cardiomyopathy
• Congenital coronary artery abnormalities
• Electrolyte imbalances
• Imbalances in blood PH
• Inherited conditions like long qt syndrome, arrhythmogenic right ventricular dysplasia
• Side effects of medication
• Stimulants like cocaine or methamphetamine

 Who is at risk of developing ventricular tachycardia?

The risk of developing ventricular tachycardia increases with age or if somebody in the family already has the condition or another heart rhythm problem. A history of a previous heart attack also increases the risk of developing ventricular tachycardia due to damaged heart muscles. There are also some medications that may increase your chances of developing ventricular tachycardia.

 What are the complications of ventricular tachycardia?

Ventricular tachycardia can lead to severe complications, especially if it lasts long. Some complications that are developed due to ventricular tachycardia include ventricular tachycardia storm and heart failure. Sustained ventricular tachycardia also increases the risk of sudden cardiac death. Other possible complications include frequent fainting spells and the inability to perform day-to-day activities such as driving.

A ventricular tachycardia storm occurs when more than three episodes of sustained ventricular tachycardia occur within 24 hours. Such a situation is associated with poor survival rates. Without treatment, one-third of the patients may experience heart failure from sustained ventricular tachycardia. 

How is ventricular tachycardia diagnosed?

Your doctor will first try to understand your symptoms and perform a physical examination while checking your pulse and listening to your heart through a stethoscope. Then, your doctor will recommend further tests to understand the ventricular tachycardia's nature and cause.

The most common test which is recommended first is the electrocardiogram or ECG. However, your doctor may also recommend other tests, such as using a Holter monitor to understand how your heart rhythm varies throughout the day or a treadmill stress test to know how the heart rate and function vary with exercise. A cardiac event monitor records when something goes wrong and may also send alerts. 

Your doctor may also need to do blood tests to understand the state of your heart health. Blood tests help to rule out even such as missed heart attacks or also help to proactively understand factors like lipid problems that can worsen your condition.

How is ventricular tachycardia treated?

Ventricular tachycardia requires treatment, especially when the symptoms last more than 30 seconds. Your doctor will try to understand the factors that cause ventricular tachycardia and try to solve those. Sometimes these treatments help to improve the abnormal heart rhythm or prevent the problems from returning. 

 Some of the treatment methods used include:

• RCA or radiofrequency catheter ablation - is a process where your doctor uses a catheter to destroy tissue and reduce the conductivity of specific pathways. Radiofrequency ablation is usually considered safe but it is sometimes linked to complications if damage to your heart and blood vessels, bleeding, or infection.
• ICD or implantable cardioverter-defibrillator These are devices that monitor and control your heart rhythm. When the device detects a problem, such as ventricular tachycardia, and detects that the problem is sustained, it quickly sends an electrical signal to your heart to get it back into normal rhythm.

Medications: Sometimes medications may be recommended to maintain a normal rhythm, but these medications usually have side effects and may be prescribed only after a thorough check of your health condition.

We hope you found this blog by Dr. Shyam Mohan useful.