Search

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.

This is the first study to assess the feasibility and accuracy of real-time 3-dimensional echocardiography (RT-3DE) for the measurements of left ventricular (LV) mass in patients with congenital heart disease (CHD) compared with magnetic resonance imaging (MRI). Twenty patients (60% men) with CHD were evaluated by MRI and RT-3DE on the same day. Their mean age was 29 +/- 8 years (range 19 to 49). RT-3DE was performed with a Philips Sonos 7500 echocardiographic system and LV mass analyses with the assistance of TomTec software. The results for LV mass obtained by manual tracing were compared with Signa 1.5-T MRI data. The acquisition of RT-3DE data sets was feasible in all 20 patients. Nine patients (45%) had good, 5 patients (25%) moderate, and 6 patients (30%) poor image quality of the 3-dimensional data set. The time of 3-dimensional data acquisition was 4 +/- 2 minutes. Off-line image processing and tracing required approximately 11 +/- 3 minutes. A very good correlation was observed between RT-3DE data with sufficient image quality and MRI (r = 0.98, y = 0.96x + 4.1, SEE 9.8 g), with a mean difference of 2.0 +/- 20 g. Interobserver agreement was excellent (r = 0.99, y = 0.97x + 3.81), with a mean difference of -1 +/- 11 g. In conclusion, the assessment of LV mass from RT-3DE data is feasible in patients with CHD. The mass of an abnormally shaped left ventricle can be determined with high accuracy and low interobserver variability in patients with good or moderate echocardiographic image quality.