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[Skeletal muscle strength following orthotopic heart transplantation]
M Quittan1, B Sturm, G F Wiesinger
1Universitätsklinik für Physikalische Medizin und Rehabilitation, Universitätsklinik für Innere Medizin II, Wien, Osterreich. michael.quittan@akh-wien.ac.at
Aim Of The Study:
Strength measurement of thigh muscles of patients after orthotopic heart transplantation (HTX) with a sedentary lifestyle, entering a cardiac rehabilitation program.
Design:
Cross-sectional study; values are compared to patients with chronic heart failure (CHF) and healthy controls.
Methods:
Isometric and isokinetic peak torque of knee extensor and flexor muscles measured on a Cybex 6000. Twenty minutes' muscle fatigue test of knee extensor muscles. Test of motor tasks of daily living.
Results:
HTX group: n = 18, age 59 +/- 7 years, body mass index (BMI) 29 +/- 5, months after HTX 46 +/- 36 months; CHI group: n = 24, age 55 +/- 8 years, BMI 25 +/- 4, months after CHF 19 +/- 16 months; control group: n = 10, age 55 +/- 6 years, BMI 26 +/- 5. The HTX group differed significantly (p < 0.05) from the CHI group. Peak torque of knee extensor muscles: HTX: 120.3 +/- 8.4; CHI: 127.8 +/- 8.0 Nm; controls: 158.3 +/- 5.5 (ANOVA p < 0.05); peak torque of knee flexor muscles: HTX 65.6 +/- 5.9 Nm; CHI 70.1 +/- 6.2 Nm; controls 84.4 +/- 3.1 Nm(ANOVA p < 0.01). Peak torque of knee extensor muscles related to body weight: HTX: 137.4 +/- 10.0 Nm%, CHI: 162.6 +/- 9.3 Nm%, control group 202.8 +/- 5.7 Nm% (ANOVA p < 0.01). Muscle fatigue test of knee extensor muscles: isometric maximal strength (maximal voluntary contraction, MCV; HTX vs. CHI): 331.6 +/- 14.7 N vs. 335.5 +/- 18.6 N (n.s.), MVC after 5 minutes 296.3 +/- 15.7 N vs. 288.4 +/- 16.7 N; MVC after 10 minutes: 283.5 +/- 15.7 N vs. 282.5 +/- 17.7 N; MVC after 15 minutes 275.7 +/- 13.7 N vs. 280.6 +/- 21.6 N. No significant differences between groups were observed. All values were significantly lower than those of healthy controls (406.2 N; 385.9 N; 373.7 N and 369.6 N). There was a significant decline in MVC after 5 minutes compared to initial values (p < 0.01), in both patients groups but not in the control group. No further decline in MVC was observed beyond the 5th minute of the fatigue test (p > 0.05).
Conclusion:
Peak torque related to body weight and muscle endurance of knee extensor muscles of sedentary patients after orthotopic HTX do not significantly differ from those of comparable patients with CHF but do differ from those of healthy controls. Specific training of muscle strength is needed for patients even several years after orthotopic heart transplantation.