VENTRICULAR TACHYCARDIA

What Is Ventricular Tachycardia?

The heart has two upper chambers, which are called atria, and two lower chambers, which are called ventricles. In normal rhythm, the heartbeat starts in the sinoatrial (SA) node, which acts as the heart’s natural pacemaker in the upper right chamber. The SA node sends an electrical signal to contract the atria. The signal then moves throughout the heart’s electrical system, which causes the ventricles to contract. In ventricular tachycardia, the electrical signal starts at a site in the lower chambers of the heart.

  • Ventricular tachycardia (VT) is an abnormally rapid heart rhythm originating from the ventricles of the heart, typically at a rate of 120 to 300 beats per minute.
  • Normal and coordinated contraction of the ventricles is important for the heart to pump blood to the brain and the rest of the body and to maintain a normal blood pressure.
  • Abnormal and fast rhythms from the ventricle may impair the ability of the pump to supply blood to the brain and the rest of the body as a result of the rapid rate and weak contractions.
  • If the heart rate increases to more than 300 beats per minute and becomes totally uncoordinated, this is usually called ventricular fibrillation (VF), which will cause sudden cardiac death.

Symptoms of Ventricular Tachycardia

Symptoms may start and stop suddenly. Brief episodes of ventricular tachycardia may not cause any symptoms in some people. Others may experience:

Sustained or more serious episodes of ventricular tachycardia may cause:

  • Loss of consciousness or fainting
  • Cardiac arrest (sudden death)

Risk Factors/Causes of VT

Any condition that puts a strain on the heart or damages heart tissue can increase your risk of ventricular tachycardia. Lifestyle changes or medical treatment may decrease the risk associated with the following factors:

  • Lack of oxygen to the heart due to tissue damage from heart disease
  • Abnormal electrical pathways in the heart present at birth (congenital heart conditions, including long QT syndrome)
  • Structural heart disease (cardiomyopathy)
  • Medication side effects
  • An inflammatory disease affecting the skin or other tissues (sarcoidosis)
  • Abuse of recreational drugs, such as cocaine
  • Imbalance of electrolytes, mineral-related substances necessary for conducting electrical impulses
  • In some cases, the exact cause of ventricular tachycardia can’t be determined (idiopathic ventricular tachycardia)
  • A family history of ventricular tachycardia or other heart rhythm disorders.

Workup for VT

The most effective way to prevent ventricular tachycardia is to reduce your risk of developing heart disease. If you already have heart disease, it is important to monitor your heart disease and follow your treatment plan to lower your risk of ventricular tachycardia.

Once you have been diagnosed with VT, you will likely be asked to undergo testing to evaluate for underlying causes. Workup may include one or some of the following:

Treatment for Ventricular Tachycardia

Based on the type of ventricular tachycardia that you have (sustained or nonsustained), what the morphology (form) of your VT is, and whether you have structural heart disease will determine what type of treatment your provider will recommend to you.

Treatment options may include one or a combination of the following:

  • Medications: Some types of VT may be susceptible to medications such as beta-blockers (metoprolol) or calcium channel blockers (diltiazem or verapamil). Other types of VT may require stronger antiarrhythmic medications such as flecainide, sotalol, or amiodarone.
  • Catheter ablation: During an ablation, the electrophysiologist is able to determine where the ventricular tachycardia signals are originating from and then target those areas of the heart by using radiofrequency. An ablation for VT can be done on either the inside and/or the outside of the heart.
  • Implantable cardioverter defibrillator (ICD): Many patients with VT are at risk of sudden cardiac death. An ICD, which provides a shock as needed, is the most effective method of restoring a potentially life-threatening rhythm such as VT or VF back to a normal rhythm.

Treatment Options for Structural Heart Disease

There are 3 treatment options for VT in patients with structural heart disease, although many patients require a combination: an ICD, antiarrhythmic medications, or catheter ablation.

ICD

Many patients at risk for VT with structurally normal hearts are at risk of sudden cardiac death and, as such, are treated with an ICD.

  • This is the most effective method of restoring a potentially life-threatening rhythm such as VT or VF back to a normal rhythm.
  • However, an ICD does nothing to prevent the heart from going into VT. The ICD is a “safety net” and has been likened to having an ambulance crew accompany you 24 hours a day.

Antiarrhythmic Medications

Antiarrhythmic medications that modify the conduction of the electric impulse of the heart can be effective in suppressing VT.

  • These medications can reduce the risk of recurrence by 75% but have potential side effects that include proarrhythmia, or the worsening of the heart rhythm. For this reason, initiation of antiarrhythmic agents often requires close monitoring.
  1. Amiodarone, the most effective drug, has many side effects, which can involve toxicity to the vital organs like the liver, thyroid, lungs, eyes, and skin.

Catheter Ablation

  • The third treatment option is catheter ablation. Because of the discomfort associated with frequent ICD shocks and the side effects of antiarrhythmic drugs, catheter ablation is an important additional treatment option for many patients already using these therapies.

VT Treatment Options

There are two main treatment options for VT in patients without structural heart disease: medications or catheter ablation.

Medications

  • For RVOT VT, medications may be prescribed to suppress VT such as beta-blockers (Metoprolol or Atenolol) or calcium channel blockers (Verapamil or Diltiazem). However, these medications only have a 25–50% rate of efficacy. Alternate therapy includes antiarrhythmic medications such as Flecainide, Sotalol, and Amiodarone. These can also be trialed if simple beta-blockers or calcium channel blockers are ineffective. Amiodarone, the most effective drug, has many side effects, which can involve toxicity to the vital organs like the liver, thyroid, lungs, eyes, and skin.

Catheter Ablation

  • Catheter ablation of RVOT-VT now has cure rates approaching 90%, which makes it a preferable option given the young age of patients with RVOT VT.
  • Ablation of other outflow tract sites such as the aortic valve cusps has also been very successful. Catheter ablation is an excellent choice for patients when medications are not effective, tolerated, or preferred.

Endocardial Ventricular Tachycardia Ablation

When is Catheter Ablation an Appropriate Treatment?

  • There are a large variety of ablations available to patients with heart rhythm disorders (catheter, surgical, or alternative techniques).
  • Catheter ablation is a minimally invasive, non-surgical procedure that is performed by an electrophysiologist (EP), an electrician for your heart.
  • The goal of ventricular tachycardia ablation is to stop the incorrect electrical signals and restore a normal heart rhythm.

Inside the Heart (endocardial ablation)

  • If your abnormal heartbeat is coming from inside your heart, special catheters are used to transmit electrical energy (radiofrequency ablation) or extreme cold (cryoablation) to the target area, damaging the tissue and causing scarring, blocking the electrical signals that are contributing to your ventricular tachycardia.
  • Our cardiologists have extensive experience with radiofrequency (RF), which is currently their preferred method of ablation. We are currently using high-energy, short-duration ablations that allow for your cardiologist to complete the procedure in a shorter time with less risk to you.
  • When the VT focus is identified, radiofrequency energy is applied to a small area (4 to 5 mm in diameter) to destroy the abnormal tissue.
  • The number of burns required to treat the VT varies among patients.

Outside the Heart (epicardial ablation)

  • If your abnormal heartbeat is being caused by tissue on the outside of your heart, it is possible to use a long needle to access your heart. The needle is inserted through the skin on your chest and advanced through the lining of the fluid-filled sack (pericardium) that surrounds your heart. A hollow tube (sheath) is inserted, and catheters are passed through the tube to access the outside surface of the heart.

Endocardial-Epicardial Ablation for VT

  • Sometimes ventricular tachycardia ablation involves treatment inside the heart (Endocardial) and (Epicardial) outside the heart at the same time. This is called a hybrid ablation.

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