Exercise capacity and skeletal muscle structure and function before and after balloon mitral valvuloplasty

• Published in: The American journal of cardiology Vol. 76; no. 10; pp. 684 - 688
• Main Authors: Barlow, Clifford W., Long, Jeremy E.H., Brown, Garry, Manga, Pravin, Meyer, Theo E., Robbins, Peter A.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.10.1995; Elsevier; Elsevier Limited
• Subjects: Adult; Analysis of Variance; Biological and medical sciences; Biopsy; Catheterization; Citrate (si)-Synthase - metabolism; Electron Transport Complex IV - metabolism; Exercise; Exercise Test; Female; Follow-Up Studies; Heart; Hemodynamics; Humans; Male; Medical procedures; Medical research; Medical sciences; Mitral Valve Stenosis - metabolism; Mitral Valve Stenosis - physiopathology; Mitral Valve Stenosis - therapy; Muscle Contraction; Muscle, Skeletal - metabolism; Muscle, Skeletal - pathology; Muscle, Skeletal - physiopathology; Muscular system; Oxygen Consumption; Physical Endurance; Skeletal system; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the heart; Physical exercise; Human; Plasty; Mitral valve; Cardiac valvular disease; Surgery; Cardiovascular disease; Narrowing; Striated muscle
• ISSN: 0002-9149; 1879-1913
• DOI: 10.1016/S0002-9149(99)80197-0

This study evaluated the effects of balloon mitral valvuloplasty (BMV) on exercise capacity and skeletal muscle structure and function in 10 subjects with mitral stenosis (mean age ± SD 33 ± 5.5). Measurements were obtained before, and 2 weeks and 4 months after BMV to provide baseline data, to examine the effects of improved hemodynamics, and to examine the effects of resumption of normal physical activity, respectively. Valvuloplasty caused an increase in mitral valve area (0.89 ± 0.04 to 1.75 ± 0.07 cm 2; mean ± SE), and an increase in resting cardiac output (3.8 ± 0.18 to 4.6 ± 0.19 L/min, p < 0.05). At early follow-up after 2 weeks, subjects did more work (31% increase, p < 0.01) and had greater maximal oxygen consumption (11% increase, p < 0.01). However, measurements reflecting skeletal muscle histology, biochemistry, and function were unaltered at this stage. Four months after BMV, subjects had a further increase in exercise capacity compared with both baseline (58% increase, p < 0.01) and early follow-up (20% increase, p < 0.05). There were associated late increases compared with baseline in quadriceps cross-sectional area (66 ± 5.8 vs 61 ± 5.5 cm 2, p < 0.05) and torque production (125 ± 14 vs 118 ± 16 Nm, p < 0.05). The percentage of slow twitch type I fibers increased compared with baseline (41 ± 2.0% vs 33 ± 3.1%, p < 0.05), as did the size of type II fibers (5.9 ± 0.49 vs 4.9 ± 0.57 μm 2 × 10 3, p < 0.05). Citrate synthase activity at late follow-up was also greater than it was before BMV (193 ± 32.1 vs 131 ± 16.2 nmol/mg/min, p < 0.05), although cytochrome oxidase activity remained unaltered. Thus, skeletal muscle abnormalities are found in patients with mitral stenosis. An early increase in exercise capacity occurs after BMV without changes in skeletal muscle structure and biochemistry. However, longer term improvements in exercise performance are associated with alterations in skeletal muscle.