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Background: In patients with complex congenital heart disease (CHD) abnormal ventricular stress responses have been reported with dobutamine stress cardiovascular magnetic resonance (DCMR). These abnormal stress responses are potential indicators of long-term outcome. However, safety and reproducibility of this technique has not been reported in a larger study. The aim of this study was to report our experiences regarding safety and intra-observer and inter-observer variability of low-dose DCMR in complex CHD., Methods: In 91 patients, 110 low-dose DCMR studies were performed with acquisition of a short axis set at rest, and during dobutamine administration (7.5 μg/kg/min maximum). We assessed biventricular end-diastolic volumes, end-systolic volumes, stroke volumes, ejection fraction and ventricular mass. Intra- and inter-observer variability for all variables was assessed by calculating the coefficient of variation (%), i.e. the standard deviation of the difference divided by the mean of 2 measurements multiplied by 100%., Results: In 3 patients minor side effects occurred (vertigo, headache, and bigeminy). Ten patients experienced an increase in heart rate of >150% from baseline, although well tolerated. For all variables, intra-observer variability was <10% at rest and during stress. At rest, inter-observer variability was 10.5% maximal. With stress-testing, only the variability of biventricular end-systolic volumes (ESV) exceeded 10%., Conclusions: In patients with complex CHD low-dose DCMR is feasible, and safe. Intra-observer variability is low for rest and stress measurements. Inter-observer variability of biventricular ESV is high with stress-testing. Whether this limits the potential usefulness of DCMR for risk assessment during follow-up has to be assessed., (Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To assess pulmonary artery (PA) size, flow variables, and wall shear stress (WSS) in patients after Fontan operation at a young age., Materials and Methods: Flow in the branch PA was obtained with phase contrast velocity-encoded cardiovascular magnetic resonance imaging in 14 patients before and after low-dose dobutamine stress (7.5 microg/kg/min) and in 17 healthy controls at rest., Results: At rest, stroke index, total flow, average, and peak flow rate were all statistically significantly lower in patients than in controls (P<0.001). With stress-testing, all variables increased in patients (P<0.001), apart from stroke index, which did not change. At rest, branch PA area did not differ between patients and controls. Distensibility was lower in patients than in controls (P<0.001). With stress-testing, area and distensibility did not change. At rest, WSS was lower in patients than in controls (P<0.001). WSS increased with stress-testing (P<0.001), but not to the same levels as during resting conditions of the control group., Conclusion: PA size is normal long-term after Fontan operation at a young age. Flow variables, distensibility, and WSS are significantly lower compared to healthy controls, and do not show adequate reactions with stress-testing, which is suggestive of pulmonary artery endothelial and/or vascular dysfunction., (Copyright (c) 2008 Wiley-Liss, Inc.)

After Fontan operation, patients are limited in increasing cardiac output and in exercise capacity. This has been related to impaired preload or other factors leading to decreased global ventricular performance with stress. To study these factors, the stress responses of functionally univentricular hearts were assessed at rest and during low-dose dobutamine stress using cardiovascular magnetic resonance imaging. Thirty-two patients after Fontan completion at young age were included (27 with total cavopulmonary connection, 5 with atriopulmonary connection; mean age 13.3 years, range 7.5 to 22.2; 23 male patients; median follow-up after Fontan operation 8.1 years, range 5.2 to 17.8). A multiphase short-axis stack of 10 to 12 contiguous slices of the systemic ventricle was obtained at rest and during low-dose dobutamine stress cardiovascular magnetic resonance imaging (maximum 7.5 microg/kg/min). With stress-testing, heart rate, ejection fraction, and cardiac index increased adequately (p <0.001). There was an abnormal decrease in end-diastolic volume and an adequate decrease in end-systolic volume (p <0.001). Stroke volume did not change with stress testing (p = 0.15). At rest, dominant left ventricles had higher ejection fractions than dominant right ventricles (p = 0.01), but this difference disappeared with stress testing. In conclusion, a functionally univentricular heart after Fontan completion at young age has an adequate increase in ejection fraction with beta-adrenergic stimulation. However, as a result of impaired preload with stress, cardiac output can be increased only by increasing heart rate.