ABSTRACT
Heart failure is associated with modifications of skeletal muscle cells, which could participate in the exercise limitation of the patients. However, the mechanical efficiency of the skeletal muscle has not been fully evaluated in these patients. We therefore measured VO2 during prolonged exercise (15 min) at constant load to obtain stable conditions. Load was chosen after maximal stress test as 35% and 65% of load at anaerobic threshold. VO2 during assisted cycling was subtracted from that during constant load to evaluate the relationship between VO2 and Watt. Twenty CHF patients (peak VO2 17.6 ml/kg/min, LVEF <35%) have been compared to 11 controls (peak VO2 40.2 ml/ml/kg). VO2 was similar in the two groups at rest and during assisted cycling. Ventilation on contrary was higher in CHF patients. The relationship between VO2 and Watt was similar in the two populations, indicating that skeletal muscle mechanical efficiency was not altered in CHF patients. In conclusion, histological modifications present in skeletal muscle of CHF patients do not translate into altered skeletal muscle efficiency.
Subject(s)
Energy Metabolism , Heart Failure/metabolism , Muscle, Skeletal/metabolism , Adult , Chronic Disease , Exercise Test/methods , Humans , Middle AgedABSTRACT
The aim of this study was to assess cardiorespiratory tolerance to exercise in children with non-operated, paucisymptomatic and untreated froms of Ebstein's anomaly. The authors undertook a prospective study in 11 children, mean age 9.6 years, who had lung function tests, cardiorespiratory exercise stress tests (bicycle ergometry N = 8, treadmill N = 3) and contrast echocardiography. All parameters of spirometry were normal. Contrast echocardiography showed a right-to-left interatrial shunt in 7 children (group 1) whereas the remaining 4 children had no shunt (group 2). The resting oxygen saturation was 97.4 +/- 2%, with no difference between the two groups. On the other hand, oxygen saturation at peak VO2 (VO2 max) was 90 +/- 9.5%, significantly lower in group 1 than in group 2 (85.7 +/- 2.2% vs 98.2 +/- 1.2%; p = 0.03). In group 1, the VO2 max was correlated to oxygen saturation (r = 0.98; p < 0.001, N = 6). The oxygen desaturation was correlated with presence of a right-to-left interatrial shunt (p = 0.01). The reduced exercise tolerance of non-operated, paucisymptomatic children with Ebstein's anomaly is due to a right-to-left interatrial shunt. In patients with poor exercise tolerance, contrast echocardiography is advised for the detection of these atrial shunts.
Subject(s)
Ebstein Anomaly/complications , Exercise Tolerance , Heart Septal Defects, Atrial/complications , Adolescent , Child , Ebstein Anomaly/diagnostic imaging , Ebstein Anomaly/physiopathology , Echocardiography, Doppler , Exercise Test , Female , Heart Septal Defects, Atrial/diagnostic imaging , Heart Septal Defects, Atrial/physiopathology , Humans , MaleABSTRACT
The aim of the study was to evaluate cardiorespiratory exercise tolerance in asymptomatic children with Ebstein's anomaly. Eleven children with a mean age of 9.6 years were prospectively studied by spirometry, cardiopulmonary exercise testing (bicycle ergometer n = 8, treadmill test n = 3), and contrast echocardiography. A right-to-left atrial shunt was detected by contrast echocardiography in 7 children (group 1), whereas no shunt was found in 4 (group 2). VO2 max was decreased [84.5 (SD = 16.8)] and was strongly correlated to oxygen saturation in group 1 (p < 0.0001). Oxygen saturation at peak uptake was significantly decreased compared to baseline [97.4 (SD = 2.0) vs 90% (SD = 9.5%), p = 0.02] and was significantly lower in group 1 than in group 2 [85.7 (2.2) vs 98.2% (SD = 1.2%), p = 0. 03]. Oxygen desaturation was related to a right-to-left atrial shunt (p = 0.01). Decreased VO2 max was also correlated to the small size of the left ventricle (p = 0.05). We concluded that decreased exercise tolerance in children with asymptomatic Ebstein's anomaly is related to a right-to-left atrial shunt and to a small left ventricle. In case of poor exercise tolerance, a contrast echocardiography should be performed to detect an atrial septal defect.
Subject(s)
Ebstein Anomaly/physiopathology , Exercise Tolerance , Adolescent , Child , Ebstein Anomaly/diagnostic imaging , Echocardiography, Doppler, Color , Exercise Test , Exercise Tolerance/physiology , Female , Follow-Up Studies , Hemodynamics , Humans , Male , Prospective Studies , Respiration , SpirometryABSTRACT
Neonatal anatomical correction of transposition of the great arteries (TGA) has transformed the prognosis of this condition but the diagnosis must be made rapidly. The aim of this retrospective study was to evaluate the benefits of antenatal diagnosis on the outcome of TGA. The cases of 50 consecutive neonates with TGA with or without ventricular septal defect hospitalised between 1989 and 1996 were reviewed. All these children underwent anatomical correction of their malformation in the neonatal period. In seventeen of the children the diagnosis was made in the antenatal period at a gestational age of 28.7 +/- 5 weeks of amenorrhea and the other 33 had a postnatal diagnosis at 6.2 +/- 13 days. The clinical and echographic features were identical in the two groups. The risk factors of mortality for the whole population were a Yacoub type B or C coronary disposition, an intramural coronary course, difficulties in reimplantation of the coronary arteries and/or peroperative haemodynamic failure. In the authors' experience, the time of diagnosis (antenatal or postnatal) did not had on the management and prognosis of TGA. Studies with larger population groups are probably necessary to demonstrate the possible benefits of antenatal diagnosis.
