Author + information
- Received June 22, 1992
- Revision received August 26, 1992
- Accepted September 8, 1992
- Published online March 15, 1993.
- ↵∗Address for correspondence: Donna M. Mancini, MD, Hospital of the University of Pennsylvania, Cardiovascular Division. 3 White Building, 3400 Spruce Street, Philadelphia, Pennsylvania 19104.
Objectives. The short- and long-term effects of valvuloplasty on exercise capacity, ventilation and skeletal muscle oxygenation were investigated to determine whether a dissociation between hemodynamic improvement and exercise capacity occurs in patients with mitral stenosis.
Background. Percutaneous balloon mitral valvuloplasty in patients with mitral stenosis results in immediate hemodynamic improvement at rest and with exercise. Improved exercise capacity has been described at 3 months after valvuloplasty. In patients with left ventricular dysfunction, acute therapeutic interventions that produce hemodynamic benefit do not immediately improve exercise capacity.
Methods. Maximal bicycle exercise with measurement of respiratory gases was performed in 11 patients with mitral stenosis before and at 48 h and 3 months after successful percutaneous balloon mitral valvuloplasty. Respiratory and leg skeletal muscle oxygenation were assessed by monitoring changes in light absorption of the serratus anterior and vastus lateralis muscles using near-infrared spectroscopy and were expressed as percent deoxygenation.
Results. Mitral valvuloplasty significantly increased mean mitral valve area from 1.0 ± 0.2 to 1.7 ± 0.3 cm2(p < 0.05). Immediately after valvuloplasty, peak exercise oxygen consumption (o2), o2at the anaerobic threshold, ventilation, peak respiratory and leg muscle deoxygenation all remained unchanged. At submaximal work loads, respiratory muscle deoxygenation was attenuated (25 W: before 12 ± 4%; 48 h 4 ± 3%; 50 W: before 10 ± 5%; 48 h 5 ± 4%; both p < 0.05).
At 3 months, significant improvement in peak o2(before 10.9 ± 5%; 3 months 14.6 ± 6.2 ml/kg per min; p < 0.05) and o2at the anaerobic threshold (before 7.1 ± 2.4; 3 months 8.4 ± 2.3; p < 0.05) were observed, whereas ventilation remained unchanged. No further improvement was seen in respiratory muscle deoxygenation. Vastus lateralis deoxygenation at submaximal work loads tended to be decreased.
Conclusions. Long-term changes in skeletal muscle and the lungs preclude immediate enhancement of exercise performance after balloon mitral valvuloplasty. Immediate symptomatic improvement probably results from an immediate decrease in the work of breathing. Long-term symptomatic improvement results from changes that occur in the peripheral skeletal musculature as well as from the reduced work of breathing.
- Received June 22, 1992.
- Revision received August 26, 1992.
- Accepted September 8, 1992.