RHE cycle may be less demanding than treadmill

Stress testing alternatives could reach a larger percentage of the patient population.

The regenerative heat exchanger cycle system permits more patients to reach maximum exercise stress test with diminished perceived exertion, according to researchers from the South Carolina Heart Center, located in Columbia. The system reduces the number of submaximal terminations and pharmacologic stress tests, according to the clinical trial results.

Many people may not be able to complete a standard treadmill stress test due to comorbidities, deconditioning or orthopedic limitations, and stress testing alternatives could test more people, according to the researchers.

Findings

Jeffrey J. Fine, PhD, vice president at Cardiovascular Innovations in Beaufort, S.C. enrolled 80 people with mild to moderate CVD in the clinical cohort study. Forty of the patients had completed a treadmill stress test at the South Carolina Heart Center within the past 12 months and were retrospectively enrolled. The experimental cohort included 40 people with CVD who used the regenerative heat exchanger (RHE) cycle and the RHE exercise stress testing protocol.

Fine found that the RHE cycle and stress testing protocol allowed a significantly higher percentage of people to achieve a maximal stress test (respiratory exchange rate [RER] >1.1). When the maximal was defined by RER, an additional 13% of patients were able to reach a maximal stress test than with the treadmill; an additional 20% of patients were able to reach maximal stress test when the researchers defined maximal by heart rate.

“This product is very effective and has the potential to change the way stress testing is conducted today,” Fine said. “By allowing a larger percentage of patients to be exercise tested vs. pharmacologic testing, the system provides tremendous benefit.”

In addition, the experimental cohort attained a higher maximal RER than the control group, and when based on heart rate, more people were able to achieve a maximal stress test in the RHE cycle group compared with the control group (68% vs. 48%). Maximal oxygen uptake (VO₂ max) did not differ between the groups. Patients using the RHE cycle exercised for a shorter amount of time and had to terminate the session due to fatigue fewer times than the control group, according to the researchers.

Seven patients in the control group had to terminate their sessions (18%) due to fatigue, compared with two patients in the RHE group (5%) due to fatigue or leg pain, according to the research. Patients in the control group were more likely to perceive exertion as “very hard,” compared with patients in the RHE cycle group, who perceived the stress test as “somewhat hard,” researchers said.

Future of stress tests?

Patients and researchers noted some drawbacks to the RHE cycle system. They found that seat adjustment to the RHE cycle is difficult, and that safety straps should be added to the pedals to reduce the potential for injury. In addition, the test protocols should be added into a computer to eliminate manual adjustment, and ECG artifact should be reduced.

Fine and colleagues recommended further study of a severely diseased population to determine the validity and value to all people with CVD. However, they noted that the RHE cycle and stress-testing protocol among the mildly diseased population was successful.

The RHE cycle and stress system’s marketing is being finalized, according to Fine, and the company is beginning to manufacture the product.