Ahmed Raza
Reviewed by
Jessica Munoz DPN, RN, CEN,
providing nurse training at Yale New Haven Health-Bridgeport Hospital since 2022. Previously in healthcare and education at Griffin Hospital, St. Vincent's College of Nursing and Sacred Heart University Medical Center.
Sudden cardiac arrest (SCA) is a medical emergency often caused by a chaotic heart rhythm known as ventricular fibrillation (VF). In VF, the heart’s chambers contract irregularly and ineffectively, preventing blood flow to vital organs. VF is recognized on cardiac monitors as a rapid, irregular waveform. If untreated, VF is fatal within 8 to 10 minutes.
Defibrillation is the process of delivering an electrical current to the heart to stop VF and restore a normal rhythm. Studies demonstrate that early defibrillation significantly improves survival rates:
Defibrillation is the primary treatment for two life-threatening cardiac rhythms:
According to the AHA, VF and pulseless VT require prompt defibrillation to improve survival. VF is the most common initial rhythm in witnessed cardiac arrests, especially in adults.
Heart disease is a leading cause of death globally, responsible for approximately 17.9 million deaths annually. Defibrillation is particularly effective when performed promptly, as survival depends on the rapid return of organized cardiac activity.
Defibrillation works by delivering a controlled electrical shock to the heart, which:
Factors influencing defibrillation success include:
Modern biphasic defibrillators optimize energy delivery by automatically adjusting for transthoracic impedance—the resistance of the chest wall.
Energy levels for defibrillation depend on the type of device and the patient’s age:
Studies demonstrate that modern biphasic defibrillators are equally effective at lower energy settings compared to higher-energy monophasic shocks, while reducing the risk of tissue damage.
While defibrillation is life-saving, certain risks must be considered:
Effective defibrillation requires proper electrode placement and adherence to protocols, including prompt response after VF onset.
Many countries have adopted public access defibrillation (PAD) programs, recognizing the importance of early intervention. These programs train laypersons to use automated external defibrillators (AEDs), simple portable devices designed to guide users in delivering a shock. Studies show public AED use improves out-of-hospital cardiac arrest (OHCA) survival rates.
Integrating early defibrillation into emergency care systems is critical to improving outcomes in sudden cardiac arrest. Communities must continue expanding PAD programs and public education efforts.
Survival rates are significantly higher when defibrillation is performed within minutes of VF onset. However, after 10 minutes of VF, the odds of survival are nearly zero. Early intervention remains the most effective way to save lives in cardiac emergencies.
Reviewed by Jessica Munoz DPN, RN, CEN, providing nurse training at Yale New Haven Health-Bridgeport Hospital since 2022. Previously in healthcare and education at Griffin Hospital, St. Vincent's College of Nursing and Sacred Heart University Medical Center.
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