Cardiopulmonary exercise testing in clinical practice

The review is dedicated to the use of the cardiopulmonary exercise testing (CPET) in clinical practice. Main modes of CPET, most popular protocols and testing methods are discussed in details. Ample space is dedicated to main parameters measuring during CPET, their physiological values and changes in different pathological states. Main indications for CPET are presented and special attention is given to the use of CPET in chronic heart failure, apnea, lung diseases, skeletal muscle fiber and mitochondrial myopathy, rehabilitation. Emerging applications of CPET like congenital heart disease, pulmonary resection and several other are also discussed.

Exercise Testing, Physical Training and Fatigue in Patients with Mitochondrial Myopathy Related to mtDNA Mutations

Mutations in mitochondrial DNA (mtDNA) cause disruption of the oxidative phosphorylation chain and impair energy production in cells throughout the human body. Primary mitochondrial disorders due to mtDNA mutations can present with symptoms from adult-onset mono-organ affection to death in infancy due to multi-organ involvement. The heterogeneous phenotypes that patients with a mutation of mtDNA can present with are thought, at least to some extent, to be a result of differences in mtDNA mutation load among patients and even among tissues in the individual. The most common symptom in patients with mitochondrial myopathy (MM) is exercise intolerance. Since mitochondrial function can be assessed directly in skeletal muscle, exercise studies can be used to elucidate the physiological consequences of defective mitochondria due to mtDNA mutations. Moreover, exercise tests have been developed for diagnostic purposes for mitochondrial myopathy. In this review, we present the rationale for exercise testing of patients with MM due to mutations in mtDNA, evaluate the diagnostic yield of exercise tests for MM and touch upon how exercise tests can be used as tools for follow-up to assess disease course or effects of treatment interventions.