Patients implanted with cardiac resynchronization pacemakers at the University of Illinois Medical Center at Chicago are breathing easier now that physicians are using a new method to help optimize heart failure therapy.
The Shape-HF Cardiopulmonary Testing System (Shape Medical Systems) allows physicians to assess the physiological effect of therapy in real time while the patient exercises at a level consistent with normal daily activity.
"The overall implication of the system is that it can improve how we program CRT devices and patient response to the device," Abraham Kocheril, MD, a professor of medicine and director of clinical electrophysiology, told Cardiovascular Business News.
The system, which gained FDA approval earlier this year and was introduced at the 2009 Heart Rhythm Society (HRS) in Boston, allows physicians to quantify shortness of breath while tracking and measuring patient progress and response to therapy. Its test parameters offer criteria for patient functional classification, correlate with biochemical markers of heart failure (BNP and ANP), and provide data that are predictive of patient mortality and hospitalization risk, according to the company.
But the biggest benefit of the method is that "it makes people feel better," Kocheril said, something that is a change from the conventional method of just putting in the CRT device. The responder rate for CRT for heart failure is about 70 percent, which means that 30 percent of patients don't feel better after implantation.
The conventional method relies on echo measurements to get the best cardiac output. "While the Shape test does have a high measure of cardiac output, it also gives gas exchange analyses to tell us how the heart and lungs are working together and whether the CRT device is having an impact on the lungs," Kocheril said.
The ability to tailor a device to a patient is just another step toward delivering more personalized medicine. As the patient exercises at a steady rate, the physician adjusts therapy settings every two minutes. At the end of the test, during which four to five therapy settings are tested, the system uses a computer algorithm to rank the physiological response to exercise at each setting, which the physician reviews to choose the most appropriate programming for the patient.
The first phase of testing--done by an advanced practice nurse and tech--might be to set the timing between the atrium and ventricle to see how much that helps the patient. The second phase would consist of adjusting the timing between the ventricles and setting those parameters--all of which can be done while the patient is walking at one mile per hour.
Kocheril said that the system is beneficial even in the 70 percent of patients who do respond well to CRT, because optimization settings could result in further improvement in symptoms and exercise capacity.
Another way of using the Shape-HF test is analyzing gas exchange parameters in patients without CRT devices. This alternative use does not require the use of a treadmill.
"It can be incorporated into different research protocols for assessing people who have heart and lung disease to get an objective baseline measurement and to get further measurements on therapy to see how well they are doing," Kocheril said.
The university's medical center pays a monthly fee to use the system. This means there is no upfront cost of buying hardware or software. According to the company, the fee per month varies depending on how many are purchased and the volume of use. "If a cardiologist put this to work today, the average cost per test is about $70," said Clarence Johnson, president of Shape Medical Systems. The per test cost takes labor and lease components into account.