For years the gold standard cardiopulmonary exercise testing has been an important method for assessing prognosis in heart failure patients. But according to Clarence Johnson, president/COO of Shape Medical Systems (St. Paul, Minnesota), that gold standard method is "very, very hard on the patient, it's a tough test to interpret, specialized training is required, it's very costly, [and] it's done in specialized centers." So, Shape has designed a device that it hopes will offer doctors a better alternative to assess heart-lung interaction in patients with chronic heart failure and other cardiopulmonary disease.

"The system is called Shape-HF cardiopulmonary testing system, and it's unique in that it takes a very complex diagnostic and risk assessment tool and makes it very simple," Johnson told Medical Device Daily.

The Shape-HF system received FDA clearance in April. Johnson, who spoke to MDD from the Minneapolis Heart Institute on Friday where patients where being tested on the Shape-HF, said the system is small and simple enough to be used right in the doctor's office.

Shape says a recent Mayo Clinic (Rochester, Minnesota) study validates the measurement accuracy of its Shape-HF system. Data collected by the system compared favorably to that of the Mayo Clinic Cardiopulmonary Research System and reflected a tight reproducibility of the results, the company noted.

The study involved testing 22 subjects simultaneously on the Shape-HF and the Mayo Clinic Cardiovascular Research System. Pneumotachs, providing air flow to the respective test systems, were connected in series for the tests. The order of the pneumotach for each system was alternated for two test runs separated by 15 minutes of rest. Each subject was tested at rest and as power was increased on a cycle ergometer to 50 Watts, 70 Watts and 125 Watts, with three minutes of exercise at each exercise work rate.

The last 30 seconds of data for each interval for each run was then averaged. The averages of all subjects for rest and the three exercise intervals were then averaged for each run. According to the company, the average values for each run showed a "remarkably consistent" parallel and match for all measurements, which included heart rate, oxygen uptake, carbon dioxide output, tidal volume, end-tidal partial pressure of carbon dioxide, oxygen saturation, and breathing frequency. Prior to each test run, the Mayo system was calibrated manually; the Shape-HF was calibrated automatically using its dynamic autocalibration feature that does not require manual calibration prior to testing, Shape said. The company added that a manuscript detailing the study is in development and will be submitted for publication.

The study validated that the system works, which is important, but most importantly it defines reproducibility, he said.

"It was not a study designed to answer clinical questions, it was designed to answer whether or not these parameters are reproducible and it turns out they are very reproducible," Johnson said. He said that was a benefit for the company, but also for the physicians because it helps them understand that they can rely on the integrity of the test's outcome.

Unlike CPX testing which is done at maximal exercise effort, which Johnson said is very difficult for heart failure patients, the Shape-HF test is done at submaximal exercise effort. The patient doesn't have to exercise to any given level of effort so they can be comfortable while doing it, he said. The test takes about six minutes, only three minutes of which are exercise, he said.

Johnson said the Shape-HF system enables "serial testing on patients so physicians can have a good look at what's happening physiologically with the patient over time." That's "unique in heart failure management today," he added.

According to the company, Shape-HF is the first gas exchange-testing device specifically designed for cardiology. Shape-HF quantifies the severity of dyspnea on exertion and fatigue and evaluates the interaction between the heart, lungs, and other organ systems. This makes it possible for the physician to evaluate therapy options for the individual patient and track patient progress, Shape said. The company added that the Shape-HF provides real-time physiological assessment to help physicians optimize cardiac resynchronization therapy at exercise levels consistent with patient daily activity.

Amdanda Pedersen, 229-471-4212; amanda.pedersen@ahcmedia.com