The heart’s ability to pump blood effectively relies on a coordinated electrical system. When this system malfunctions, it can lead to various heart rhythm problems, some of which are life-threatening. Ventricular tachycardia (VT) is one such arrhythmia where the heart’s lower chambers beat unusually fast, and medical intervention, often involving electrical shock, becomes necessary to restore a normal rhythm.
What is Ventricular Tachycardia
Ventricular tachycardia (VT) is an abnormal heart rhythm that originates in the ventricles, the heart’s lower pumping chambers. This condition causes the ventricles to beat at a very rapid rate, typically between 150 to 250 beats per minute, though sometimes as slow as 110 beats per minute. A normal resting heart rate usually falls between 60 to 100 beats per minute.
When the heart beats too quickly due to VT, it cannot fill adequately with blood between beats, reducing the amount of oxygenated blood pumped to the body. This diminished blood flow can lead to various serious symptoms such as chest pain, dizziness, shortness of breath, or fainting. If prolonged, VT can progress to cardiac arrest, which can lead to sudden death.
Electrical Shock Therapy for VT
Electrical shock therapy is a direct and immediate treatment for ventricular tachycardia. The two main types are defibrillation and synchronized cardioversion, both delivering electrical energy to reset the heart’s activity.
Defibrillation is an urgent, unsynchronized, high-energy shock used for life-threatening arrhythmias like pulseless ventricular tachycardia. The unsynchronized shock is delivered immediately to stop chaotic electrical activity within the heart, allowing the heart’s natural pacemaker to re-establish a normal rhythm. For pulseless VT, an initial biphasic defibrillation shock of 120 Joules (J) is common, which can be increased to 200 J if needed.
Synchronized cardioversion, in contrast, is used for ventricular tachycardia when the patient has a pulse, especially if the VT causes instability. This procedure delivers a lower-energy electrical shock precisely timed with a specific point in the heart’s electrical cycle, specifically the R-wave of the QRS complex. This synchronization avoids shocking during the T-wave, a vulnerable period where an unsynchronized shock could induce a more dangerous rhythm like ventricular fibrillation. For monomorphic VT with a pulse, synchronized cardioversion often starts with a biphasic shock of 100 J, which can be increased up to 200 J.
After the Initial Shock
After electrical shock therapy for ventricular tachycardia, immediate and ongoing medical care is important. Healthcare providers closely monitor the patient’s heart rhythm and overall condition to ensure stability and detect any recurrence of VT or other arrhythmias.
Identifying and addressing the underlying cause of VT is a key next step. VT can occur due to existing heart conditions like damage from a prior heart attack, cardiomyopathy, or heart valve disease. This may involve further diagnostic tests and specialized treatments.
While the electrical shock corrects the immediate rhythm disturbance, additional treatments are needed to prevent future VT episodes. These include anti-arrhythmic medications, catheter ablation to destroy the specific heart tissue causing abnormal signals, or the implantation of a device such as an implantable cardioverter-defibrillator (ICD). An ICD continuously monitors heart rhythm and can deliver an electrical shock if it detects a life-threatening arrhythmia. Long-term medical follow-up is important for managing heart health and reducing recurrence risk.