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(Chest. 2004;125:1306-1314.)
© 2004 American College of Chest Physicians

Exercise Performance and Skeletal Muscles in Patients With Advanced Chagas Disease*

María Montes de Oca, MD; Sonia H. Torres, MD, PhD; José G. Loyo, MD; Francia Vazquez, MD; Noelina Hernández, PhD; Begoña Anchustegui, BS and Juan J. Puigbó, MD, PhD

* From the Pulmonary Division (Drs. Montes de Oca and Vazquez), University Hospital of Caracas, Central University of Venezuela; Section for Muscle Adaptation (Drs. Torres, Hernández, and Ms. Anchustegui), Institute of Experimental Medicine, Cental University of Venezuala; Centro Médico de Caracas (Dr. Loyo); and Cardiomyopathy Unit (Dr. Puigbó), University Hospital of Caracas, Caracas, Venezuela.

Correspondence to: María Montes de Oca, MD, CCS 5150, PO Box 025323, Miami, FL 33102-5323; e-mail: mmdeoca{at}cantv.net

Study objective: This study was designed to evaluate the peripheral muscle metabolic and structural characteristics in patients with advanced Chagas disease (ChD), and whether they were related with exercise performance.

Design: Cross-sectional study.

Setting: Outpatient cardiomyopathy clinic of a university hospital.

Patients and methods: We studied 11 stage II patients, 8 stage III patients, and 11 healthy volunteers. All patients underwent exercise testing and peripheral muscle biopsies. The muscles were also studied in control subjects. Muscle biopsy specimens were analyzed for histochemical characteristics. In six patients, the muscle was studied ultrastructurally.

Results: The data demonstrate more glycolytic and less oxidative capacity of the peripheral muscle in patients with advanced ChD (increased proportion of type IIb fibers, increased proportion of fibers with low nicotinamide adenine dinucleotide diaphorase activity, high proportion of darkly stained fibers for {alpha}-glycerophosphate dehydrogenase activity, and lower levels of citrate synthase). Many capillaries in patients with ChD had an abnormal aspect: they were either closed or showed a thicker wall. The ultrastructural study also showed fiber atrophy and abnormal capillaries even in patients with normal functional capacity. Some muscle characteristics (enzyme activity, mean cross-sectional area of the fiber, and capillarity) related with exercise parameters (anaerobic threshold, and peak oxygen pulse).

Conclusions: These findings indicate that patients with advanced ChD have decreased oxidative capacity and a shift to anaerobic metabolism in the skeletal muscle. They also suggest that muscular abnormalities are related to oxygen delivery, which is probably reduced in part by the abnormal muscle microvasculature. Those changes could affect oxygen extraction, and therefore exercise tolerance in these patients.

Key Words: cardiomyopathy • Chagas disease • exercise test • pulmonary gas exchange • skeletal muscle






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