Yes, pulseless ventricular tachycardia (pulseless V-tach) is a shockable rhythm. It is one of only two cardiac arrest rhythms treated with defibrillation, the other being ventricular fibrillation (V-fib). The American Heart Association’s cardiac arrest algorithm places pulseless V-tach on the same treatment pathway as V-fib, meaning the immediate priority is delivering an electrical shock as quickly as possible.
Why Pulseless V-Tach Is Shockable
In pulseless V-tach, the heart’s lower chambers are still producing organized electrical activity, but they’re beating so fast (over 100 beats per minute, often much higher) that they never get a chance to fill with blood between contractions. The result is a heart that’s electrically active but mechanically useless: no blood moves forward, no pulse can be felt, and organs begin losing their blood supply within seconds.
A defibrillator shock works by resetting that chaotic-but-organized electrical pattern, giving the heart’s natural pacemaker a chance to take back control and restart effective contractions. This is why timing matters so much. Survival drops by roughly 5 to 10 percent with every additional minute between collapse and the first shock. A rhythm that starts as pulseless V-tach can deteriorate into V-fib or eventually flatline (asystole), which carries a far worse prognosis.
Defibrillation vs. Synchronized Cardioversion
This distinction trips people up, so it’s worth clarifying. When someone has V-tach but still has a pulse, the treatment is synchronized cardioversion. That means the device times its shock to land at a specific point in the heart’s electrical cycle, avoiding the vulnerable window near the T wave that could accidentally trigger V-fib.
When V-tach is pulseless, synchronization is unnecessary. The patient is in cardiac arrest, and the goal is simply to stop the abnormal rhythm as fast as possible. The shock is delivered unsynchronized, which is technically called defibrillation. In practical terms: pulse present means synchronized cardioversion, pulse absent means defibrillation.
How Much Energy Is Used
For a biphasic defibrillator (the type found in most modern hospitals and AEDs), the initial shock is typically 120 to 200 joules, depending on the manufacturer’s settings. For older monophasic devices, the dose is 360 joules. If the first shock doesn’t work, subsequent shocks should be at the same energy level or higher, stepping up until the maximum available dose is reached.
An automated external defibrillator (AED) handles this decision-making automatically. It analyzes the rhythm, determines whether a shock is advised, and delivers the appropriate energy. Pulseless V-tach is one of the rhythms an AED will recognize as shockable.
What Happens Between Shocks
Defibrillation alone doesn’t save most patients. The AHA’s adult cardiac arrest algorithm builds a structured cycle around each shock. After the first shock, CPR resumes immediately for two minutes. During that window, rescuers establish IV or intraosseous access and begin giving epinephrine every 3 to 5 minutes to help maintain blood flow to the heart and brain.
If the rhythm remains pulseless V-tach after additional shocks, antiarrhythmic medications enter the picture. Amiodarone is the first-line option, given as a 300 mg initial dose followed by a second dose of 150 mg if needed. Lidocaine is an alternative. These drugs help stabilize the heart’s electrical activity so that the next shock has a better chance of restoring a normal rhythm.
Throughout this process, the team also investigates reversible causes. The standard mnemonic covers ten possibilities: low blood volume, low oxygen, acidosis, abnormal potassium levels (too high or too low), hypothermia, toxins or drug overdoses, cardiac tamponade (fluid compressing the heart), tension pneumothorax (air compressing a lung), and blood clots in the coronary arteries or lungs. Fixing one of these underlying problems can be the difference between a rhythm that keeps coming back and one that finally converts.
What Happens After the Heart Restarts
When a pulse returns, the situation shifts from resuscitation to stabilization. A 12-lead ECG is obtained right away to look for signs of a heart attack or other treatable causes. Blood pressure is closely managed, with the goal of keeping mean arterial pressure at 65 mmHg or higher to protect the brain and other organs.
Oxygen is given at 100% initially until reliable oxygen saturation readings are available, then adjusted downward to avoid giving too much. For patients who remain unconscious after their pulse returns, targeted temperature management (keeping body temperature controlled) is maintained for at least 36 hours. This cooling strategy helps protect the brain from the damage that follows prolonged loss of blood flow.
Why the Pulse Makes All the Difference
Ventricular tachycardia exists on a spectrum. A person with V-tach and a stable pulse might feel lightheaded or have chest discomfort but is still conscious and perfusing their organs. That person gets medications first and, if needed, a carefully timed synchronized shock. A person with V-tach and no pulse is in cardiac arrest, functionally no different from someone in V-fib. They need CPR and an unsynchronized defibrillation shock without delay.
The core takeaway: pulseless V-tach is always shockable, and speed is everything. Every minute without defibrillation significantly reduces the chance of survival. If you witness someone collapse and an AED is available, applying it immediately is the single most important intervention you can provide before professional help arrives.