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An individualized protocol is more accurate than a standard protocol for assessing exercise capacity after heart
M T Olivari1, C W Yancy, R L Rosenblatt
1Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, USA.
Background:
Subjective improvement and normalization of exercise tolerance are reported by most of patients after heart transplantation. However, objective measurements often do not confirm the subjective improvement. This disparate observation may be related to the methods used to test exercise tolerance. We postulated that an individualized, more gradual exercise protocol might allow a more accurate assessment of exercise tolerance than standard protocols for patients with transplanted, denervated hearts.
Methods:
Eleven stable heart recipients exercised on a treadmill using two different protocols. Protocol A was a standard Naughton's protocol, and protocol B was an individualized Naughton's protocol, in which the slope of the treadmill was increased only after a steady state in heart rate and oxygen consumption had been achieved and maintained for 30 seconds.
Results:
Patients exercised longer and reached a higher workload with protocol B than with protocol A. Time to anaerobic threshold was significantly prolonged by protocol B. Minute ventilation and oxygen consumption at anaerobic threshold were significantly higher with protocol B than with protocol A. At peak exercise, heart rate, oxygen consumption, oxygen pulse, and minute ventilation were similar with the two protocols and exceeded 75% of the predicted corresponding maximal values for a normal matched population.
Conclusions:
The use of an individualized, gradual exercise protocol for heart transplant recipients detected a significantly better submaximal exercise capacity than a standard protocol, which is more consistent with the subjective improvement in functional capacity in this population.