When someone goes into cardiac arrest, their heart stops beating and can’t pump blood to the brain or the rest of the body. Ventricular fibrillation (VF) is a form of cardiac arrest that occurs when the chambers (ventricles) of the heart that usually efficiently pump blood instead begin to quiver (fibrillate) in an irregular pattern. Someone experiencing VF needs immediate medical attention to survive, which should include calling 911, starting chest compressions (cardiopulmonary resuscitation or CPR) and locating an automated external defibrillator (AED). AEDs—which are available in many public places, including gyms and schools—can help shock the heart back into a normal pumping rhythm.
Current CPR guidelines recommend that an electrical shock be delivered every two minutes. Let’s compare this recommendation with a printed road map. Before real-time travel apps such as Google Maps or Waze, we relied on printed maps to show us the desired route to our destination. There were no warnings about police, no estimated travel times and definitely no updated route recalculations to use after missing a turn. We’ve come a long way in developing newer and easier-to-follow GPS systems. But unlike the evolution we’ve seen with digital maps, not as many cutting-edge updates have been made with the way we perform CPR.
A VF wave pattern is always changing—it improves or worsens depending on the quality of CPR. However, according to the current CPR guidelines, electrical shocks are given without considering the energy state of the heart. My lab believes that every unsuccessful shock unnecessarily damages the heart tissue.
In addition to measuring heart performance using an electrocardiogram (ECG)—which visually shows the electrical rhythm of the heart—we calculate a value called the amplitude spectral area (AMSA) to measure the energy in the heart. The formula for AMSA has existed since the 1980s, but computers now let us perform the calculations very quickly. AMSA technology is currently available in AEDs and is being studied in Italy.
AMSA acts as our GPS, telling us “where we are” in terms of the heart’s energy. Someone with a high-energy heart has a high likelihood of surviving cardiac arrest, while a low-energy heart needs improvement. We can use AMSA in real time to better direct the timing of electrical shocks from the AED and guide our actions during CPR.
Using AMSA as our guide, we can deliver shocks only when they can be truly effective and prevent giving unnecessary, harmful shocks. This new technology gives us turn-by-turn navigation of not only how to get to our destination, but when to turn and how long to stay on the current route.
Salvatore Aiello is pursuing a combined MD/PhD degree at Rosalind Franklin University in Chicago. His research focuses on resuscitation and translating laboratory work into clinical practice. Outside of research, Aiello leads the Medical Humanities group on campus with the hopes of finding ways to better integrate the arts into the education of health care professionals.