Exploring the Answer to: What drug is used to restart the heart?

October 13, 2025 •

3 min read

During cardiopulmonary resuscitation (CPR), pharmacological interventions are critical, though no single drug can guarantee success. So, what drug is used to restart the heart? The primary medication administered is epinephrine, a potent vasopressor used to increase blood flow to vital organs during a cardiac arrest. This article provides a comprehensive overview of the medications involved in Advanced Cardiac Life Support (ACLS).

Quick Summary

Epinephrine is the primary drug used in advanced cardiac life support (ACLS) to increase blood flow during cardiac arrest. Antiarrhythmics like amiodarone and lidocaine are also used for specific heart rhythms.

Key Points

Epinephrine is the primary drug: Used in all cardiac arrest situations to increase coronary and cerebral blood flow during CPR through its alpha-adrenergic effects.
Drugs cannot restart the heart alone: Medications are adjuncts to high-quality CPR and rapid defibrillation.
Rhythm determines antiarrhythmic use: Amiodarone and lidocaine are reserved for shock-refractory ventricular fibrillation and pulseless ventricular tachycardia.
Magnesium is for specific arrhythmias: Magnesium sulfate is indicated for Torsades de Pointes, not for routine use.
Sodium bicarbonate is not routine: Used only in specific circumstances like severe acidosis due to hyperkalemia or certain overdoses.
Atropine is no longer routinely used: Modern guidelines do not recommend atropine for asystole or pulseless electrical activity.
Survival depends on comprehensive care: While drugs improve the chance of return of spontaneous circulation, long-term survival is influenced by many factors including CPR quality.

The Resuscitation Process: More Than Just a Drug

Pharmacological interventions are only one part of a complete resuscitation effort. Essential components of treating cardiac arrest include high-quality chest compressions and swift defibrillation for certain heart rhythms. A defibrillator is crucial for stopping ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT), allowing the heart's natural rhythm to resume. Medications support these vital actions.

Epinephrine: The Primary Vasopressor

Epinephrine, also known as adrenaline, is the first-choice vasopressor in all types of cardiac arrest and is given early in the resuscitation process.

How Epinephrine Works

Epinephrine affects alpha (α) and beta (β) adrenergic receptors. Its alpha-adrenergic effects are key during CPR, causing peripheral vasoconstriction that raises blood pressure in major arteries. This action boosts blood flow to the heart and brain, improving the chances of regaining spontaneous circulation (ROSC).

When is Epinephrine Administered?

Epinephrine administration follows Advanced Cardiovascular Life Support (ACLS) guidelines and depends on the detected cardiac rhythm. For non-shockable rhythms (Asystole or Pulseless Electrical Activity - PEA), epinephrine is given as soon as vascular access is available. For shockable rhythms (VF or pVT), it's given after initial defibrillation attempts fail.

Antiarrhythmics: Correcting Electrical Chaos

Antiarrhythmic drugs help stabilize the heart's electrical activity for VF or pVT that persists despite several defibrillation attempts (shock-refractory).

Amiodarone

Amiodarone is a potent Class III antiarrhythmic. It is the preferred antiarrhythmic for shock-refractory VF and pVT and is given intravenously (IV) or intraosseously (IO).

Lidocaine

Lidocaine, a Class Ib antiarrhythmic, blocks sodium channels to reduce electrical activity. It's an alternative to amiodarone for shock-refractory VF/pVT, especially if amiodarone isn't available.

Other Critical Medications in Specific Scenarios

Magnesium Sulfate

Used for Torsades de Pointes or suspected low magnesium levels.

Sodium Bicarbonate

Generally not advised for routine cardiac arrest. Reserved for specific metabolic issues like severe acidosis from hyperkalemia or certain overdoses.

Atropine

No longer recommended for routine use in asystole or pulseless electrical activity (PEA).

Pharmacological Interventions by Cardiac Rhythm


Cardiac Rhythm	Initial Intervention (after CPR starts)	Recommended Drug Therapy
Ventricular Fibrillation (VF) & Pulseless VT	Immediate Defibrillation	Epinephrine (after failed initial shocks if rhythm persists)
VF & Pulseless VT (Shock-refractory)	Continue CPR and Defibrillation	Amiodarone OR Lidocaine
Asystole	Immediate CPR	Epinephrine as soon as possible
Pulseless Electrical Activity (PEA)	Immediate CPR	Epinephrine as soon as possible
Torsades de Pointes (Polymorphic VT)	Defibrillation	Magnesium Sulfate

Understanding Outcomes and Limitations

While drugs like epinephrine may increase the likelihood of regaining spontaneous circulation, they do not guarantee long-term survival or good neurological outcomes. The success of drug treatment is influenced by factors like the cause of arrest, time to treatment, and the quality of CPR and other support. Some research suggests epinephrine might negatively affect brain microcirculation, potentially impacting recovery. Ongoing research continues to explore optimal drug use.

For more detailed and current information, refer to guidelines from organizations like the American Heart Association (AHA) and other international resuscitation bodies. {Link: Merck Manuals https://www.merckmanuals.com/professional/critical-care-medicine/cardiac-arrest-and-cardiopulmonary-resuscitation-cpr/cardiopulmonary-resuscitation-cpr-in-adults} offer comprehensive details.

Conclusion

Addressing 'what drug is used to restart the heart?' involves understanding a multi-faceted strategy. Epinephrine is the primary medication to improve vital blood flow and increase the chances of successful resuscitation. Antiarrhythmics like amiodarone and lidocaine are used for specific rhythms resistant to initial shocks, and other drugs such as magnesium sulfate address particular causes. These drug treatments support the essential life-saving measures of high-quality CPR and defibrillation.

Frequently Asked Questions

No, drugs alone cannot reliably restart a heart. Pharmacological interventions are part of a broader resuscitation effort that includes high-quality chest compressions and, for certain rhythms, electrical defibrillation.

The first medication given in most cardiac arrest scenarios is epinephrine (adrenaline). It is administered early to increase coronary and cerebral perfusion pressure.

Antiarrhythmic drugs are used for specific rhythms that are resistant to initial electrical shocks. They are administered for 'shock-refractory' ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT).

Routine use of sodium bicarbonate is not recommended for cardiac arrest. Its use is limited to specific clinical situations, such as hyperkalemia or an overdose involving tricyclic antidepressants.

Magnesium sulfate is used specifically to treat a type of abnormal heart rhythm called Torsades de Pointes or when the patient is known or suspected to have low magnesium levels (hypomagnesemia).

Yes, modern guidelines no longer recommend the routine use of atropine for asystole or pulseless electrical activity (PEA). It was historically used for these conditions, but research has led to its removal from current recommendations.

While epinephrine increases the chance of a return of spontaneous circulation (ROSC), studies have raised concerns about its impact on long-term neurological outcomes due to potential negative effects on microvascular blood flow. However, its use remains standard practice based on current evidence.

The choice and timing of medications during cardiac arrest are determined by established international and national guidelines, such as those from the American Heart Association (AHA). These guidelines are based on scientific evidence and guide healthcare professionals in administering appropriate treatments.