Ventricular Tachycardia—Meaning, Causes, Treatment and Catheter Ablation for VT
Ventricular tachycardia, or VT, is a serious condition in which a person suffers from abnormal heart rhythm disorders. The abnormal heartbeats originate from the lower chambers of the heart.
In VT, the heart rate normally exceeds 150 to 200 beats per minute, which is way more than the normal heart rate (60-100 heartbeats per minute). Such fast heartbeats prevent the heart from pumping blood in an appropriate manner. And it can further lead to loss of consciousness, dizziness, extreme fatigue, shortness of breath, and sudden cardiac arrest as well.
To prevent these health dangers, it is important to get the right treatment at the right time. After medications, catheter ablation for VT stands as the most effective. It is a minimally invasive procedure that eliminates faulty electrical pathways in the heart. As the root of VT is targeted, the heart can restore a normal heart rate.
In order to understand how catheter ablation for VT is the most suitable procedure, it is important to know VT in detail. If you knew how healthy electrical signals in the heart work and what causes VT, you would gain a better understanding of the benefits of catheter ablation. It will help you know why catheter ablation has slowly become a preferred treatment for VT.
Understanding Ventricular Tachycardia (VT)
Your heart runs by means of a perfectly tuned electrical system. This system is based on the sinoatrial node, which is located in the right atrium. It acts as the natural pacemaker for your heart.
By sending impulses through particular electrical pathways, which further trigger the contraction of atria and ventricles, it keeps your heart working in an appropriate way. However, if a person is suffering from ventricular tachycardia, this normal pattern is disrupted.
The ventricles start giving electrical impulses from an unusual, abnormal site at a chaotic or rapid pace. It no longer responds to ideal top-down signals. These faulty signals generally occur due to the following three reasons:
Structural Heart Disease
Poor heart health is a prime reason for VT. Congenital abnormalities, cardiomyopathy, or previous heart failure can distort the heart muscle and create a pathway for VT.
Idiopathic VT
When an abnormal electrical focus arises near the outflow tracts of the ventricle, people, even having a normal heart, can experience VT.
Scar Tissue from Previous Heart Damage
Another common reason behind VT is a scar in the ventricles. Such scars can occur due to a past heart attack or myocardial infarction. It creates faulty pathways where impulses can re-enter, loop, or spin abnormally, which is also known as reentry circuits. These circuits halt normal electrical conduction and let VT erupt and sustain.
Irrespective of the main cause, VT can have serious consequences such as fainting, progression to ventricular fibrillation, and reduced cardiac output. Hence, it is crucial to get it treated at the right time.
Medicines, ICDs and Catheter Ablation for VT
Medicines
Medicines can suppress VT; however, they might not eliminate it completely. They often leave some side effects as well. So, when antiarrhythmic medicines like amiodarone do not have the potential to treat ventricular tachycardia, doctors prefer the use of ICDs (implantable cardioverter-defibrillators) and catheter ablation for VT.
ICDs
ICDs generally give a shock, which helps in eliminating VT once it begins, but they cannot prevent VT from occurring. Multiple ICD shocks are not recommended, as they can cause both emotional and physical distress. If a person needs ICDs frequently, it may be a sign of worsening heart health.
Catheter Ablation
This medical procedure eliminates the main electrical source causing VT. It uses either extreme heat or cold to damage the responsible tissue completely. This results in decreased frequency of VT, fewer or no ICD shocks, and reduced symptoms.
In many cases, especially for patients having VT storm or recurrent VT where they suffer back-to-back episodes of VT in a very short time period, catheter ablation becomes a lifesaver.
What happens during Catheter ablation for VT
Preparation for Ablation
Patients undergo imaging studies such as cardiac MRI, which help the doctor to examine heart health and structure and spot areas of scar. In some cases, patients undergo a CT scan for a detailed mapping as well. During the ablation procedure, patients are generally given deeper anesthesia.
Catheter Insertion
Catheter—a thin, flexible tube—is inserted into the blood vessels of the patients through the neck, groin area, or arm. Then the electrophysiologist guides the catheter through the arteries or veins into the heart using 3D mapping, symptoms, and X-ray imaging.
Electrical Mapping
The medical team creates a detailed electrical map of the patient’s ventricles to spot the origin site of VT and understand its circulation. This mapping can be done in two ways: • Activation Mapping • Substrate Mapping It is the most meticulous and time-consuming part of the ablation procedure.
Ablation of Faulty Tissue
After identifying the site where faulty signals originate, the electrophysiologist applies either: Radiofrequency (extreme heat to cauterize the abnormal tissue) Or Cryoablation (extreme cold to freeze the abnormal tissue) The abnormal focus or reentry pathway is eliminated, which ensures that electrical impulses do not travel in an abnormal pattern. This results in a massive reduction or complete elimination of VT.
Testing
After carrying out the procedure, the electrophysiologist uses programmed electrical stimulation to induce VT again. This is done to test the effectiveness of catheter ablation. If they cannot induce VT, and the remaining VT is less frequent, slower, and non-dangerous, ablation is marked as successful.
Recovery Period
Once the ablation is done, doctors remove the catheters and apply pressure at the insertion site. The patient is monitored while the anesthesia wears off. In general, patients are kept under observation overnight. However, in some cases, doctors might extend the stay in the hospital for two days.
Frequently Asked Questions
Who can have catheter ablation for ventricular tachycardia?
Patients who have:
- Undergone multiple ICD shocks
- Recurrent VT in spite of being on antiarrhythmic medication
- VT storm
- No tolerance for antiarrhythmic medications
- Structural heart disease
- Idiopathic VT
What are the risks associated with catheter ablation?
Even though catheter ablation is a safe medical procedure, there may be some risks in rare situations; they include:
- Blood vessel injury
- Damage to normal conduction pathways
- Blood clots
- Stroke
- Groin hematomas or bleeding
- Recurrence of VT
