Listening to the heart with a stethoscope is the most widely used method for the detection of heart murmurs, but Zargis Medical (Princeton, New Jersey) has developed an auscultatory device it hopes will become the new standard of care.
The Zargis Acoustic Cardioscan, cleared by the FDA earlier this month, is the first computer-aided device to support primary care physicians in analyzing heart sounds for the identification of suspected murmurs, a potential sign of heart disease. It improves upon a stethoscope which is subject to the limitations of the human auditory system by electronically acquiring, processing and analyzing heart sounds and providing printable results. If a murmur has been detected, the Cardioscan assists physicians in their referral decision to a specialist or for further testing.
"This is the first product which provides murmur detection on the basis of the heart sound recording alone," Ray Watrous, PhD, Zargis' founder and chief technology officer, told Cardiovascular Device Update. "We are looking forward to introducing this technology to physicians, and hopefully it will be helpful to them."
The non-invasive, portable device consists of an electronic stethoscope connected to a laptop computer and printer. The Cardioscan software implements voice-guided protocols through a graphical user interface.
"We provide voice prompts for listening to the heart on the chest surface at four standard locations," Watrous explained. The display features a graphical representation of the chest, "which has little points that light up in sequence to help the person using the device to track which site they should be listening to on the chest," he said. "We record 20 seconds of heart sounds at each of the four locations. That data is then stored in the computer and analyzed, and the results are presented in graphical form."
The software uses a pattern-matching, signal-processing algorithm that analyzes the two dominant heart sounds important for the detection of murmurs S1, or the "lub" sound and S2, or the "dub" sound which identify the systolic and diastolic phase of the heart. Should there be any murmurs present, the device will draw a shaded box around the murmurs to indicate at which location they were found and where those murmurs occur in the heart-beat cycle, Watrous said.
"There are many reasons why someone may have a murmur, and thankfully, they are not all related to heart disease," Watrous said. "On the other hand, in certain heart diseases such as valve disease, stenosis of the valve or a congenital anomaly in heart such as septal defect, the flow of blood across the septal wall or through a stiffened or prolapsing valve often will generate a murmur, and that's what physicians are listening for and trying to identify."
As part of the company's FDA submission, a clinical study found that the Cardioscan detected heart murmurs with a sensitivity of 91.8% and a specificity of 68%. Cardioscan also achieved 91% sensitivity and at least 92% positive predictivity in the identification of S1 and S2. In comparison, an earlier study published by the American Medical Association (AMA; Chicago, Illinois) reported only a 20% correctness among 450 internal medicine and family practice physician residents in identifying 12 basic heart sounds and murmurs with a stethoscope.
"This device could provide doctors with a much needed tool to help them provide better care to their patients while optimizing the healthcare process," Zargis President and Chief Executive Officer Shahram Hejazi, PhD, said in a statement.
Watrous called the Cardioscan's ability to record the heart sounds "very valuable" in tracking a patient's heart sound history by comparing recordings. "It also gives a way for the physician to print out a hard copy of the heart sounds, which could be placed in the patient's file so there's a physical, graphical record of the heart sounds."
The company said the Cardioscan would initially be launched to a select group of physicians, teaching hospitals and other healthcare professionals. "This product is intended to support primary care physicians in making diagnostic decisions and referral decisions," Watrous said. "We see a use also for cardiologists, and we have ongoing R&D which will lead to additional diagnostic features that will be very helpful for physicians in screening and doing diagnostics evaluation of their patients."
He declined to cite a price for the device, but said it is a less costly diagnostic method than echocardiography or ultrasound. "Depending on the circumstances, echocardiography can be very expensive. Typically, what will happen is if a physician listens to someone's heart and determines that they have a murmur which is suspicious, they will refer them to a cardiologist and in many cases directly for cardiac ultrasound. The sonographer will spend 20 to 30 minutes with the patient, a cardiologist will read the echocardiogram, and that whole process can cost $1,000," Watrous said. "So in comparison to that, we are offering a very low-cost alternative."
Watrous, who wrote the key patents surrounding the technology while at Siemens Corporate Research (also Princeton), said the Cardioscan has been in development for seven years. Zargis Medical, originally called Sound Diagnostics, was formed in 2001 to commercialize the acoustic technology pioneered at Siemens in partnership with Speedus (Brooklyn, New York), through its Speedia Wireless subsidiary. A majority-owned subsidiary of Speedus, Zargis Medical currently has two other products on the market related to the Cardioscan.
The Zargis Acoustic Cardioscan Viewer is a phonocardiogram software application that allows the user to record, condition, display, and print heart sounds that are recorded through an electronic stethoscope. "This is mainly for people who want to, and feel comfortable with, analyzing heart sounds on their own," Watrous said.
The Zargis Acoustic Cardioscan Tutor is a non-invasive teaching system that analyzes heart sound recordings for the presence of suspected murmurs. Using advanced acoustic signal processing algorithms, this product identifies S1, S2, S3 and murmurs that users may interpret as those same heart sounds. A graphical user interface displays the results. "This is a product that has all of the functionality of the Cardioscan with additional analytical capabilities that are very useful in teaching auscultation of the heart," he said.
And the company plans to add more features and functions to the Cardioscan. "There's a whole inventory of heart sounds, and all of these sounds have diagnostic significance." Watrous said. "Our goal is to be able to detect and identify all of them so the physician can be able to have the best interpretation of the sounds being recorded in the patient."