Defibrillators | Restoring a normal heart rhythm

From early manual devices to modern automated systems, the journey of defibrillation technology reflects significant progress in patient outcomes and survival rates.

Defibrillators, critical tools in emergency medicine, have significantly improved survival rates for individuals experiencing cardiac arrest by promptly restoring normal heart rhythm. With millions affected by cardiac arrest annually, defibrillators play a pivotal role in interrupting life-threatening cardiac arrhythmias, particularly ventricular fibrillation, and ventricular tachycardia. By delivering a controlled electric shock either externally or internally, they depolarize the heart muscle, allowing its natural pacemaker to resume normal rhythm. This process is vital as it can be the only way to restore a normal heart rhythm and save lives. Evolving from experimental stages they are widely available today as AEDs in public spaces, enabling even untrained bystanders to administer life-saving treatment during emergencies.

The defibrillator restores a normal heartbeat in individuals experiencing cardiac arrhythmias or sudden cardiac arrest. It encompasses various settings, including hospitals, ambulances, public spaces, and even homes. Modern defibrillators are designed with advanced technologies, including automated features that analyze the heart’s electrical activity and deliver shocks only when necessary. Defibrillators are undergoing a remarkable evolution, transforming into sleek, efficient, and user-friendly lifesaving devices. The latest advancements in defibrillator technology are revolutionizing its design, giving it a modern and streamlined appearance while enhancing its functionality. The devices are user-friendly, often equipped with visual and audio prompts to guide both medical professionals and laypersons through the resuscitation process.

The portability of defibrillators, particularly AEDs, allows for rapid deployment in various settings, making them indispensable tools in the chain of survival.

There seems to be an urgent need for improved education and awareness regarding defibrillator usage to enhance their utilization rates and ultimately improve outcomes for cardiac arrest patients. Recent research presented at the British Cardiovascular Society Conference reveals that despite defibrillators being available, they were used in only ten percent cardiac arrest cases.

That said, in countries as cost conscious and as vast as India, the need for low cost portable defibrillators has always been there. Data shows that cardiac arrests, leading to mortality outside the hospital settings are as high as 70 percent. And early defibrillation within minutes is the prime treatment to improve survival.

Springer Science has published a paper proposing the development of a low-cost, portable, disposable defibrillator to improve accessibility and survival rates. The proposed design features an encased portable battery with a capacitor that delivers biphasic shocks tailored for both pediatric and adult patients.

The device allows for up to six shocks with stored energy and includes a small display for viewing heart rhythm. Tests conducted at the Sree Chitra Tirunal Institute for Medical Sciences and Technology at Thiruvananthapuram, Kerala demonstrated a high level of accuracy, around 98.03 percent in diagnosing cardiac rhythms.

The developed system is user-friendly, portable, and compact, with the ability to select between adult and pediatric shock options and control energy release. Weighing only 1.3 kg and sized like a notebook, the device represents a significant advancement in accessibility. Future enhancements may include conversion to a wireless Internet of Things (IoT) based system for improved operation feasibility.

A valuable addition in the wearable cardioverter defibrillators (WCD) category was reported by researchers at the American Heart Association Scientific Sessions held in Philadelphia. Unlike current garment-based devices, the Jewel patch-wearable cardioverter defibrillator (P-WCD) is a low-profile, lightweight system that adheres to a patient’s torso, enabling near-continuous protection.

The device is water-resistant and can be worn during activities of daily living including showering. The device uses a novel machine learning algorithm that accurately detects abnormal heart rhythms, resulting in a low false alarm rate and timely defibrillation when needed.

The device met its primary efficacy and safety endpoints. Instead of having to teach and train patients how to manage the wearable defibrillator, this device aligns with the patient’s lifestyle and asks very little of the patient. With the advances made in medical therapy for heart failure, some patients are getting better and only have temporary risk for sudden cardiac arrest. It is not yet approved for commercial use in the United States. Further research is warranted to refine patient selection and optimize the use of WCD systems.

The ICDs that were used in the 1980s were solely intended to identify and abolish ventricular fibrillation by administering a high-energy shock. Because those initial gadgets could not identify unstable ventricular tachycardias (VTs) that may develop into ventricular fibrillation, additional pacemakers were necessary to offer alternate bradycardia pacing, resulting in lethal synergy. In the early 1990s, new-generation devices came into clinical use. ATP was incorporated in these devices and low-energy shocks for terminating VTs, substantial programmability, and telemetry functionalities. For quick charging time and delivering high-voltage shocks, devices initially used had cylindrical aluminium electrolytic capacitors and silver vanadium pentoxide batteries. Nevertheless, due to the short service time and high maintenance of these batteries, lithium-silver vanadium manganese oxide batteries are currently being utilized, extending an ICD’s service life.

An ICD system’s ability to successfully resuscitate a potentially deadly ventricular arrhythmia depends on effective detection and timely shock delivery. The ICD lead and ICD generator are vital elements of this device. The lead, for instance, is an absolute lifeline whose job is to transmit essential data about the cardiac rhythm to the ICD generator, which then delivers life-sustaining treatment as necessary. Malfunctioning of an ICD lead can result in severe outcomes, such as pacemaker failure, defibrillator failure, inappropriate shocks, and even death.

AI integration. AI is increasingly integrated into defibrillator technology, revolutionizing its capabilities. Through AI algorithms, defibrillators can analyze complex cardiac data in real-time, allowing for more accurate and timely diagnosis of life-threatening rhythms. AI-driven defibrillators can adapt to individual patient needs, optimizing treatment delivery and improving patient outcomes. The incorporation of AI holds promise for enhancing the effectiveness and efficiency of defibrillator therapy, marking a significant advancement in cardiac care.

In clinical practice, both external defibrillators (EDs) and implantable cardioverter defibrillators (ICDs) rely on sophisticated shock advisory algorithms to distinguish shockable from non-shockable heart rhythms, with recent advancements incorporating machine learning (ML) algorithms for enhanced accuracy. The paramount importance lies in promptly identifying shockable rhythms such as ventricular fibrillation (VF) and ventricular tachycardia (VT) to deliver timely, life-saving interventions.

AI holds promise in reducing response times and improving the efficiency of rhythm identification, potentially saving more lives. Despite these advancements, sudden cardiac arrests (SCAs) remain a significant global health concern, underscoring the critical need for effective interventions like CPR and defibrillation.

The integration of AI into prehospital emergency care offers opportunities to enhance detection of shockable rhythms, predict resuscitation outcomes, and improve overall patient care. Nonetheless, challenges such as data quality, regulatory complexities, and security vulnerabilities must be addressed through collaborative efforts among researchers, healthcare providers, and regulatory bodies to fully leverage AI’s potential and improve survival rates in cardiac arrest management.

Drones equipped with AED. There is an urgent need for novel initiatives to shorten the time to defibrillation as well as to reach out-of-hospital cardiac arrests occurring in private homes. Researchers at Karolinska Institute, Sweden have evaluated the possibility of alerting drones equipped with automated external defibrillators (AED) to patients with suspected cardiac arrest.

Over the course of an 11-month trial in the suburbs of Gothenburg, the team showed they could get the devices to the scene of a medical emergency before an ambulance 67 percent of the time. Generally, the AED arrived more than three minutes earlier, giving bystanders time to attach the device before paramedics reached the patient. In one case, this saved a patient’s life.

Admittedly, the approach will not work everywhere. In rural areas, the technology would likely lead to even bigger reductions in response time, but lower population density means the cases would be too few to justify the investment. And in big cities, ambulance response times are already relatively rapid and high-rise buildings would make drone operation challenging.

One promising future direction could be to combine drone-delivered AEDs with existing smartphone apps that are used to quickly alert volunteers trained in first aid to nearby medical emergencies.

The future of defibrillation continues to evolve, driven by a shared commitment to improving cardiac care and outcomes worldwide.