Advanced Cardiovascular Life Support (ACLS) uses standardized protocols to manage life-threatening emergencies like cardiac arrest. The immediate goal of ACLS is to restore spontaneous circulation and breathing through a rapid, structured response. Pulseless Ventricular Tachycardia (PVT) is one of the four core rhythms leading to cardiac arrest, requiring immediate and specific ACLS intervention. Its swift and correct management is directly tied to a patient’s chance of survival, demanding a shock-first approach.
Defining Pulseless Ventricular Tachycardia
Pulseless Ventricular Tachycardia is a state where the heart’s ventricles are contracting extremely rapidly, typically at a rate between 150 to 250 beats per minute. This rapid electrical activity originates abnormally within the lower chambers of the heart. The defining feature of this condition is the electrical activity being decoupled from the mechanical function of the heart.
The heart muscle receives organized electrical signals, but the contractions are so fast that the ventricles cannot fill with blood between beats. This lack of filling causes a cessation of effective cardiac output, meaning no blood is pumped to the body’s organs. The patient presents without a palpable pulse, despite the monitor displaying an organized rhythm. This distinguishes PVT from Ventricular Tachycardia with a pulse, and from Ventricular Fibrillation (V-Fib), which involves chaotic and disorganized electrical activity.
Recognition and Differentiation on the Monitor
Identifying PVT begins with observing the patient’s cardiac monitor, where the rhythm appears as a series of wide, rapid QRS complexes. These complexes, which represent ventricular depolarization, are typically uniform in shape, giving the rhythm a monomorphic appearance. The rate is usually fast, often exceeding 180 beats per minute, and the rhythm is generally regular.
Observing this wide-complex tachycardia pattern immediately triggers a time-sensitive clinical assessment. Checking for a pulse is necessary, as the electrical rhythm alone is insufficient for diagnosis. If the patient has a pulse, the treatment pathway involves synchronized cardioversion and antiarrhythmic medications. Failing to recognize PVT delays the immediate defibrillation required for a pulseless patient.
The Core ACLS Treatment Sequence
The management of PVT follows the shockable branch of the ACLS Cardiac Arrest Algorithm, prioritizing electrical therapy and high-quality cardiopulmonary resuscitation (CPR). Once PVT is confirmed by the absence of a pulse, high-quality chest compressions must be initiated immediately (100 to 120 compressions per minute). The defibrillator should be attached without delay, and a shock delivered as soon as it is ready. Current guidelines recommend using a biphasic defibrillator, with the initial energy dose typically set between 120 and 200 Joules, or the maximum manufacturer recommendation.
Following the shock, chest compressions are immediately resumed for two minutes before checking the rhythm again, minimizing interruptions to blood flow. If the PVT persists after the first shock and two minutes of CPR, the sequence continues with a second shock and the administration of the primary vasopressor medication.
Epinephrine is given at a dose of 1 milligram intravenously or intraosseously every three to five minutes throughout the resuscitation effort. Epinephrine increases perfusion pressure to the heart and brain, enhancing the chance of successful defibrillation and return of spontaneous circulation. If the rhythm remains PVT after the third shock, an antiarrhythmic drug is introduced to stabilize the heart’s electrical system.
The first-line antiarrhythmic for persistent PVT is Amiodarone, administered as a 300 milligram intravenous or intraosseous bolus. If the arrhythmia continues despite further shocks, a second dose of Amiodarone, 150 milligrams, can be given. Alternatively, Lidocaine may be used, with an initial dose of 1 to 1.5 milligrams per kilogram. These medications suppress abnormal electrical activity in the ventricles, but they are adjuncts to the core therapies of CPR and defibrillation.
Identifying and Addressing Underlying Causes
Even with execution of the defibrillation and medication sequence, a patient may remain in PVT if the underlying cause of cardiac arrest is not identified and corrected. ACLS providers use the “H’s and T’s” mnemonic to quickly review the most common reversible causes:
- H’s (Systemic Problems): Hypovolemia (low blood volume), Hypoxia (lack of oxygen), Hydrogen ion excess (acidosis), Hypo- or Hyperkalemia, and Hypothermia (low body temperature).
- T’s (Mechanical or Toxic Issues): Tension pneumothorax, Tamponade (cardiac), Toxins, and Thrombosis (coronary or pulmonary).
If the cause is Hypovolemia, administering intravenous fluids is as important as giving epinephrine. If PVT is refractory (does not respond to standard treatment), addressing these underlying conditions simultaneously with the resuscitation algorithm is paramount.