Silicon Labs microprocessors are at the heart of a new type of ambulatory cardiac monitor designed for continuous operation for up to 14 days, which requires high performance with relatively low power consumption.
Cardiac monitors have been available for more than a century. Yet, Dr. Gust H. Bardy, a cardiac electrophysiologist, had low confidence in their ability to accurately capture arrhythmias. When his wife, Lorene, became ill with heart rhythm problems, his skepticism increased. It was not possible to get clear and precise recordings of her various rhythm disorders. She died April 26, 2012, from cardiac arrest that was the result of broader cardiac and vascular abnormalities. Exactly one year later, Dr. Bardy began a journey to improve both the signal quality and the diagnostic accuracy of ambulatory heart rhythm monitors both as a public health mission and to honor Lorene. It was at this time that he launched Bardy Diagnostics and engaged a small team of engineers to translate the goal of cardiac rhythm diagnostic precision into the circuit board of the device that monitors the heart. Much of this work revolved around showing more nuance in the recorded ECG, educating the team on the diversity and complexity of cardiac rhythm disorders, and significantly altering and improving the software routinely used with ambulatory ECG monitors.
To develop a more accurate method for identifying heart arrythmias by improving the signal quality, diagnostic accuracy, and practicality of ambulatory heart rhythm monitors.
Silicon Labs’ EFM32TG210 MCU offers the size, low power consumption, and integrated peripherals to help Bardy Diagnostics create a small, lightweight portable cardiac monitor.
The Carnation Ambulatory Monitor, or CAM, is the first P-wave centric cardiac rhythm monitoring device designed specifically for accuracy and to accommodate the active lifestyles of users.
Today, the WHO estimates that cardiovascular diseases (CVDs) are the leading cause of death globally, taking an estimated 17.9 million lives each year. Heart rhythm disorders account for a large proportion of these deaths. Accurately and rapidly identifying those at the highest risk of arrhythmias and ensuring they receive appropriate and timely treatment can prevent premature deaths. New technologies offer the chance to increase the accuracy and efficacy of traditional ECG monitoring devices by resolving smaller signals and finer details in the cardiac waveform leading to more specific diagnoses.1 2
Creating a Smarter Niche with CAM, an Ambulatory Cardiac Monitor
Accurate diagnosis starts with an accurate ECG tracing. The better-known electrocardiogram – or ECG/EKG – is a device designed to record the electrical activity of the heart. This device is non-invasive, usually involving electrodes placed on the skin of the chest and limbs to measure electrical activity from the heart. The output signal can be used to determine or detect abnormal heart rhythms (i.e., arrhythmias) that may cause cardiac arrest, stroke, or loss of consciousness. These monitors, known as long-term ECG (LT-ECG) monitors, are worn 24/7 for up to 14 days without a change of monitoring electrodes, allowing patients to shower, sleep comfortably, and engage in exercise. This is in stark contrast to the historical Holter monitor, worn for just 1-2 days with multiple dangling wires and simplistic engineering and heart rhythm analysis. Dr. Bardy’s invention, the CAM™ Patch, is an LT-ECG device offering exceptional comfort and compliance.
“While a traditional monitor is excellent at detecting R-waves (the largest electrical signal from the heart), and certainly an important part of the cardiac waveform, the R-wave alone is insufficient to diagnose many abnormal heart rhythms," says Gabriel. "There is just so much other information buried in low amplitude shifts of the other waves. What appears to be a small shift in waveform shape can prove critical for helping people get the specific treatment they need to improve their health and manage serious disease.”
The CAM system at all levels of the design needed to be optimized to capture these tiny and delicate signals. And yet, human factors were of utmost importance as the device needed to be minimally intrusive to the patient’s daily activities.
“Let’s be honest, when you have an octopus of cables and sensors wrapped around your body, as has been the case with typical cardiac monitors, about the only place you are going to be is hiding in your bedroom.”
From Dr. Bardy’s perspective, if you want to practice good medicine and revolutionize a field absolutely, every aspect of the design is critical. Every piece must be made with love, from the packaging to the training of those who do the overreading of the ECG. And yet, everything pivots around the key feature of the Bardy monitor: the ability to sense very fine, nuanced electrical signals from the heart. This is an electrical design challenge as much as it is mechanical, biological, and chemical. Size, weight, and comfort are absolutely critical for success. But without the subtle details of the ECG, all else has little value.
Reflecting the company’s unwavering dedication to quality and clarity, as well as its patient-first ethos, Gabriel doesn’t mince his words. “Having the gumption to try something different is key. What was state-of-the-art 50 years ago is bad medicine today. The CAM is very much like a flower, the petals being the different aspects of the design: chemical, mechanical, electrical, firmware, software, hardware, algorithms, and especially the humans that make the final overreading decisions. If just one petal is removed, the beauty of the flower is greatly diminished.”