Oxygen uptake versus exercise intensity: a new concept in assessing cardiovascular exercise function in patients with congenital heart disease

OBJECTIVE—To assess the relation between exercise intensity and oxygen uptake during graded exercise in paediatric patients who underwent surgical repair of congenital heart disease, and to compare it with conventional measures of aerobic exercise function.
DESIGN—Cross sectional study. Exercise testing was performed on a treadmill and gas exchange was measured on a breath by breath basis.
PATIENTS—29 patients who underwent an atrial switch operation for transposition of the great arteries (TGA) (mean (SD) age at testing 10.3 (2.5) years) and 30 patients who underwent total repair of tetralogy of Fallot (TF) (age 12.1 (3.3) years) performed graded exercise testing. Exercise responses were compared with data obtained in 24 normal controls (age 11.4 (2.6) years).
RESULTS—The slope of oxygen uptake versus exercise intensity averaged 1.50 (0.64) ml O₂/min²/kg in the patients with TGA and 1.68 (0.75) ml O₂/min²/kg after TF repair, both lower (p < 0.005) than in normal controls (2.42 (0.68) ml O₂/min²/kg). The lower slope of oxygen uptake was correlated with a subnormal value for ventilatory anaerobic threshold, which averaged 78.0 (13.3)% of normal in TGA and 85.1 (10.6)% in TF. This was associated with a steeper slope (p = 0.001) of carbon dioxide output versus oxygen uptake above the ventilatory anaerobic threshold in TGA (1.26 (0.20)) and TF (1.20 (0.18)) compared with the normal controls (1.05 (0.13)), and also a steeper slope of ventilation versus carbon dioxide in TGA (47.0 (15.4)) and TF (41.5 (13.7)) than in the controls (30.3 (8.5)).
CONCLUSIONS—Calculation of the steepness of the slope of oxygen uptake versus exercise intensity is a valid measurement of oxygen flow to the exercising tissues, which may be limited in congenital heart disease.


Keywords: congenital heart disease; exercise testing; oxygen uptake; oxygen uptake kinetics     

Exercise performance and training in cardiac patients with atrial fibrillation

PURPOSE: Exercise training in cardiac patients with chronic atrial fibrillation (AF) has received little attention in the literature. Therefore, this study compared exercise performance and the effect of an exercise training program over a period of 3 months in patients with and without AF. METHODS: Data in patients with AF (n = 19) were compared with a control group of patients in sinus rhythm (n = 44), drawn from a database of 2,116 patients. Patients performed a maximal exercise test on the bicycle until exhaustion before and after an ambulatory exercise training program where exercise training was offered 3 times a week for 3 months. RESULTS: Before training, peak oxygen uptake (VO2) was significantly lower in patients with AF compared with the control group (1271 +/- 368 versus 1496 +/- 414 mL/min, P < 0.05). Exercise training significantly increased peak VO2 in both groups (+31%, P < 0.001 in AF and +25%, P < 0.001 in the control group). The gain in peak VO2 did not significantly differ between both groups. A significant decrease in resting heart rate was achieved in both groups after exercise training. AF was also a significant and independent determinant of peak VO2 in the total database, but not of the change in peak VO2. CONCLUSIONS: Exercise training significantly improves exercise performance in cardiac patients with AF. AF affects exercise performance but does not impair the beneficial effects of training. Patients with chronic AF should therefore not be dissuaded from participating in exercise training after a cardiac event.     

The caregene study: muscle-specific creatine kinase gene and aerobic power in coronary artery disease.

In 927 biologically unrelated Caucasian patients with coronary artery disease it was investigated whether the NcoI restriction fragment length polymorphism of the muscle-specific creatine kinase (CKMM) gene is associated with aerobic power and with the response to physical training. Physical training significantly (P<0.001) increased peak oxygen consumption in the GG, AG and AA NcoI genotypes. Covariate-adjusted peak oxygen consumption at baseline, after training and the response to training were not different across CKMM NcoI genotypes.     

Effect of exercise training in patients with an implantable cardioverter defibrillator.

AIMS: Little research exists on exercise performance and training in patients with an implemented cardioverter defibrillator (ICD) and only in a limited number of patients. This study aims to investigate the effect of exercise training in ICD patients in comparison to the effects in other cardiac patients without an ICD. METHODS AND RESULTS: 92 ICD patients were compared with a control group of 473 patients. A maximal cycle-spiroergometric test was performed until exhaustion before and after an ambulatory exercise training programme. Exercise training was offered 3 times a week for 3 months. The cut-off heart rate was set at (ICD detection rate -20 beats/min). At baseline, the ICD patients had a lower peak oxygen uptake (VO(2)) compared to the control group. Training effects were smaller for peak VO(2) (mL/min/kg) and oxygen pulse in the ICD group (18 vs. 27%, p = 0.006 and 11 vs. 17%, p = 0.016, respectively). Several appropriate shocks were delivered during (n = 5), and in between (n = 7), testing or training and one inappropriate shock during training. CONCLUSIONS: ICD patients can safely participate in an exercise training programme with favorable results. A randomised control study with evaluation of the physical and the psychosocial effects is warranted.     

The CAREGENE study: polymorphisms of the beta1-adrenoceptor gene and aerobic power in coronary artery disease.

AIMS: The heritability of aerobic power and of the response to physical training has been shown in healthy subjects. beta(1)-Adrenergic receptor (beta(1)AR) function affects exercise performance. This study aims to investigate whether the Ser49Gly and Gly389Arg polymorphisms of the beta(1)AR gene or their haplotypes are associated with aerobic power or its response to physical training in coronary artery disease (CAD). METHODS AND RESULTS: Nine hundred and thirty-five biologically unrelated Caucasian patients with CAD who had exercised until exhaustion during graded bicycle testing at baseline and after completion of 3 months of exercise training from 1990 to 2001 (n = 1095) were eligible for inclusion in the CAREGENE (CArdiac REhabilitation and GENetics of Exercise performance) study. Polymorphisms were detected using the invader assay (Third Wave Technologiestrade mark, Madison, Wisconsin, USA). Patients with the Gly49Gly genotype had significantly higher covariate-adjusted aerobic power at baseline than those with Ser49Ser and Ser49Gly (P < 0.05). Adjusted aerobic power at baseline was highest in the Ser49-Gly389/Gly49-Gly389 and Gly49-Arg389/Gly49-Arg389 haplotype combinations. Aerobic power increased significantly (P < 0.001) with physical training. There was no association with the effect of physical training. CONCLUSION: Ser49Gly and haplotype combinations of Ser49Gly and Gly389Arg of the beta(1)AR gene are associated with aerobic power, but not with the response to physical training in patients with CAD included in the CAREGENE study.     

Creation of an appendicovesicostomy mitrofanoff from a preexisting appendicocecostomy utilizing the spilt appendix technique

Continent catheterizable channels have revolutionized reconstructive surgery to achieve both urinary and fecal continence. The Mitrofanoff and Malone antegrade continent catheterizable channels offer improved quality of life relative to permanent incontinent stomas. A frequently employed surgical option for creating a Mitrofanoff when an existing appendicocecostomy exists involves harvesting a separate piece of intestine. If however the Malone has preceded the creation of a Mitrofanoff, we describe a surgical technique that may avoid the need for a bowel harvest and resultant anastomosis. We report our series of patients utilizing a novel alternative strategy in the select clinical circumstance of an existing appendicocecostomy to expand the armamentarium of the urologic reconstructive surgeon.