VENTRICULAR TACHYCARDIA

VENTRICULAR TACHYCARDIA

VENTRICULAR TACHYCARDIA

Ventricular tachycardia (VT or V-tach) is a type of abnormal heart rhythm, or arrhythmia. It is classified as either nonsustained (lasting less than 30 seconds and terminating spontaneously) or sustained with a heart rate greater than 100 beats/min. In individuals without heart disease, non­sustained ventricular tachycardia is generally associated with a benign prognosis. In patients with structural heart disease, nonsustained ventricular tachycardia is associated with an increased risk of subsequent symptomatic ventricu­lar tachycardia and sudden death, especially when seen more than 48 hours after myocardial infarction.

Ventricular tachycardia is a frequent complication of acute myocardial infarction and dilated cardiomyopathy but may occur in chronic coronary disease, hypertrophic cardiomyopathy, myocarditis, and in most other forms of myocardial disease. It can also be a consequence of atypical forms of cardiomyopathies, such as arrhythmogenic right ventricular cardiomyopathy. However, idiopathic ventricu­lar tachycardia can also occur in patients with structurally normal hearts.

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Accelerated idioventricular rhythm is a regular wide complex rhythm with a rate of 60–120 beats/ min, usually with a gradual onset. It occurs commonly in acute infarction and following reperfusion with thrombo­lytic medications. Treatment is not indicated unless there is hemodynamic compromise or more serious arrhythmias.

Torsades de pointes, a form of ventricular tachycardia in which QRS morphology twists around the baseline, may occur in the setting of severe hypokalemia, hypomagnese­mia, or after administration of a medication that prolongs the QT interval. In nonacute settings, most patients with ventricular tachycardia have known or easily detectable cardiac disease, and the finding of ventricular tachycardia is an unfavorable prognostic sign.

Symptoms and Signs

Patients commonly experience palpitations, dyspnea, or lightheadedness, but on rare occasion may be asymptom­atic.

Syncope or cardiac arrest can be presenting symptoms in patients with underlying cardiac disease or other severe comorbidities. Episodes may be triggered by exercise or emotional stress.

Complications of ventricular tachycardia

Ventricular tachycardia may cause severe complications, especially the longer it lasts.

The complications may include:

  • Ventricular tachycardia storm. This consists of three or more episodes of sustained ventricular tachycardia in 24 hours. This is associated with poor survival rates both in the short and long term.
  • Heart failure. Without treatment, 30 percent of people with sustained ventricular tachycardia may experience heart failure.
  • Sudden cardiac death. Sustained ventricular tachycardia is associated with a risk for sudden death.

Diagnosing ventricular tachycardia

Your doctor will make a diagnosis by performing a physical exam and running certain tests. During the exam, your doctor will listen to your heart, and if you’re responsive, they may ask about your symptoms. They’ll also check your pulse and blood pressure.

If ventricular tachycardia is suspected, your doctor will order certain tests. These may include:

  • Electrocardiogram (ECG). An ECG measures the electrical activity of the heart. It records a picture of the heart’s electrical activity, allowing doctors to spot abnormalities.
  • Cardiac MRI (CMRI). This imaging test uses strong magnets and radio waves to produce clear, cross-sectional images of the heart. This lets doctors look at the heart in more detail.
  • Transesophageal echocardiography. In this procedure, an ultrasound probe is inserted into the esophagus. The probe uses high-frequency sound waves to create detailed images of the heart. These pictures give doctors a better view of the heart structures and valves.

How is VT treated?

Treatment will depend on your symptoms. No treatment may be needed if:

  • You don’t have underlying heart disease
  • You are not having difficult symptoms
  • Your VT episodes don’t last a long time

If you do have symptoms, your healthcare provider might prescribe medicine (a beta-blocker or antiarrhythmic medicine) to control your heart rhythm.

For VT that is sustained or life-threatening, an implantable cardiac defibrillator (ICD) may be used. This is especially true when there is no reversible cause identified or if you have another condition that predisposes you to further episodes of VT. This small device is implanted into your chest. It’s connected to your heart with wires. When an abnormal heartbeat occurs, the ICD can either overdrive pace the VT to stop it or, if needed, deliver an electric shock to restore your normal heartbeat.

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Some VT may be treated with catheter ablation. This procedure uses radiofrequency energy to destroy the abnormal heart tissue that is causing the rapid heartbeat.

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