Pulseless ventricular tachycardia (V-Tach) is a life-threatening cardiac rhythm disturbance characterized by extremely rapid, abnormal electrical activity originating in the lower chambers of the heart. This chaotic signaling prevents the ventricles from effectively filling or pumping blood, leading to an immediate cessation of circulation. As a form of sudden cardiac arrest, it requires immediate medical intervention, since the lack of blood flow to the brain and organs can cause death within minutes.
Immediate Recognition and Foundational Care
Treatment begins with the immediate assessment of responsiveness and confirmation of pulselessness, which signifies cardiac arrest. This triggers the activation of emergency medical services and the rapid commencement of Cardiopulmonary Resuscitation (CPR). High-quality CPR is the foundation of resuscitation, manually circulating oxygenated blood until definitive treatment is delivered.
High-quality compressions must be delivered at a rate of 100 to 120 per minute, with a depth between 2 and 2.4 inches for adults. Ensuring the chest fully recoils after each compression is necessary to maximize coronary perfusion pressure. Interruptions must be minimized; if an advanced airway is not present, compressions are paused briefly after every 30 compressions to deliver two rescue breaths.
Essential Role of Defibrillation
Defibrillation is the definitive treatment for pulseless V-Tach because the underlying problem is an electrical malfunction. The controlled electrical shock momentarily depolarizes all heart muscle cells simultaneously. This electrical reset stops the chaotic rhythm, allowing the heart’s natural pacemaker to resume a normal, organized rhythm.
Advanced biphasic defibrillators are the standard, requiring less power than older monophasic devices. Initial energy settings for biphasic devices typically range from 120 to 200 Joules (J); monophasic devices require a fixed dose of 360 J. The shock must be delivered immediately upon rhythm confirmation, followed instantly by resuming chest compressions. Subsequent shocks, if necessary, should be given at an equal or higher energy level, continuing the cycle of two minutes of CPR followed by a brief pause for rhythm check and shock.
Pharmacological Interventions During Resuscitation
Medication administration is integrated into the two-minute cycles of CPR and defibrillation attempts. The first-line drug used across all pulseless arrest rhythms is Epinephrine, a potent vasoconstrictor. A dose of 1 milligram (mg) is administered intravenously (IV) or intraosseously (IO) every three to five minutes. Epinephrine causes peripheral vasoconstriction, redirecting blood flow to the core circulation and improving supply to the heart and brain.
If pulseless V-Tach persists after initial shocks and Epinephrine, an antiarrhythmic medication is introduced to stabilize the heart’s electrical activity. Amiodarone is the preferred agent, given as an initial dose of 300 mg via IV or IO route. This drug suppresses the abnormal ventricular electrical focus by affecting multiple ion channels.
Lidocaine serves as an alternative antiarrhythmic, with an initial dose of 1 to 1.5 milligrams per kilogram (mg/kg) given IV or IO. Both antiarrhythmics aim to make the heart more responsive to the electrical shock. If V-Tach continues, a second dose of Amiodarone (150 mg) or Lidocaine (0.5 to 0.75 mg/kg) may be given after subsequent defibrillation attempts.
Identifying and Correcting Reversible Causes
Treating pulseless V-Tach requires continuous physical interventions while simultaneously searching for and correcting any underlying causes of the arrest. Medical teams rely on a systematic approach to diagnose these potentially reversible conditions, often memorized using the mnemonic “H’s and T’s.” Addressing these precipitants is important for successful resuscitation.
The “H’s” and “T’s” refer to systemic, structural, or mechanical problems:
- Hypoxia (lack of oxygen)
- Hypovolemia (low blood volume)
- Hypo- or Hyperkalemia (potassium imbalance)
- Hypothermia (low body temperature)
- Hydrogen ion excess (acidosis)
- Tension pneumothorax
- Tamponade (fluid around the heart)
- Toxins (drug overdose)
- Thrombosis (coronary or pulmonary clots)
While the immediate treatment protocol continues, the medical team concurrently investigates the patient’s history and clinical signs to identify and treat these specific issues, such as administering fluids for hypovolemia or reversing an overdose.