After the arterial switch operation (ASO) for transposition of the great arteries (TGA), many patients have an impaired exercise tolerance. Exercise tolerance is determined with cardiopulmonary... Show moreAfter the arterial switch operation (ASO) for transposition of the great arteries (TGA), many patients have an impaired exercise tolerance. Exercise tolerance is determined with cardiopulmonary exercise testing by peak oxygen uptake (VO2peak). Unlike VO2peak, the oxygen uptake efficiency slope (OUES) does not require a maximal effort for interpretation. The value of OUES has not been assessed in a large group of patients after ASO. The purpose of this study was to determine OUES and VO2peak, evaluate its interrelationship and assess whether exercise tolerance is related to ventricular function after ASO. A cardiopulmonary exercise testing, assessment of physical activity score and transthoracic echocardiography (fractional shortening and left/right ventricular global longitudinal peak strain) were performed to 48 patients after ASO. Median age at follow-up after ASO was 16.0 (IQR 13.0-18.0) years. Shortening fraction was normal (36 +/- 6%). Left and right global longitudinal peak strain were reduced: 15.1 +/- 2.4% and 19.5 +/- 4.5%. This group of patients showed lower values for all cardiopulmonary exercise testing parameters compared to the reference values: mean VO2peak% 75% (95% CI 72-77) and mean OUES% 82(95% CI 77-87); without significant differences between subtypes of TGA. A strong-to-excellent correlation between the VO2peak and OUES was found (absolute values: R = 0.90, p < 0.001; normalized values: R = 0.79, p < 0.001). No correlation was found between cardiopulmonary exercise testing results and left ventricle function parameters. In conclusion, OUES and VO2peak were lower in patients after ASO compared to reference values but are strongly correlated, making OUES a valuable tool to use in this patient group when maximal effort is not achievable. Show less
In CHF patients exercise capacity is decreased (low physical fitness). The degree of exercise intolerance in CHF is paralleled by an increased mortality, moreover, several studies suggest that... Show moreIn CHF patients exercise capacity is decreased (low physical fitness). The degree of exercise intolerance in CHF is paralleled by an increased mortality, moreover, several studies suggest that increasing exercise capacity in CHF improves prognosis. Therefore, improving exercise capacity is one of the major issues in CHF-related treatment. Besides this decreased exercise capacity CHF patients also have a low autonomic fitness (high neurohumoral activation and a low baroreflex sensitivity (BRS)), which causes structural end-organ damage and increases mortality. The current therapeutic regimen in CHF mainly focuses on the blocking of the neurohumoral activation but not on the removing of neurohumoral activation. In this thesis we have studied the effects of exercise and cardiac resynchronization therapy (CRT) on both physical and autonomic fitness in CHF patients. We found that exercise improves both physical and autonomic fitness. Also, we showed that is possible to increase BRS without actual exercise, by mimicking exercise associated nerve traffic by means of TENS (transcutaneous electrical nerve stimulation). Furthermore, we found that CRT acutely improves BRS, and this improvement had predictive value for the anatomical response after six months of CRT. In conclusion, both exercise and CRT are capable to improve the fitness of CHF patients Show less
