Exercise MR imaging in the assessment of pulmonary regurgitation and biventricular function in patients after tetralogy of fallot repair.

Abstract

To assess the responses of pulmonary regurgitation (PR) and biventricular function to submaximal exercise by using a magnetic resonance (MR) imaging exercise protocol with young adult patients who underwent tetralogy of Fallot repair at a young age. Fifteen patients with corrected tetralogy of Fallot (mean age, 17.5 years +/- 2.5 [SD]) underwent MR imaging at rest and during exercise for the evaluation of PR and biventricular function. Results were compared with findings from 16 control subjects (mean age, 17.5 years +/- 2.3). Mean age at tetralogy of Fallot repair was 2.1 years +/- 1.6, and mean follow-up time after repair was 15.4 years +/- 2.6. Exercise level at MR imaging was calculated individually and corresponded to 60% of peak oxygen uptake. The parameters of cardiac function obtained at rest and during exercise were compared by using a paired t test. An unpaired t test was used to compare parameters of cardiac function between patients and control subjects. PR decreased during exercise (from 27 mL/m(2) +/- 17 to 23 mL/m(2) +/- 15; P =.012). At rest, right ventricular (RV) ejection fraction was normal (>47%) in 80% of patients. RV response to exercise in the patient group was abnormal compared with response in the control group, as demonstrated by an increase in RV end-diastolic volume index (132 mL/m(2) +/- 36 to 137 mL/m(2) +/- 38; P =.041) and no significant change in end-systolic volume index or ejection fraction. In only one patient, RV ejection fraction increased by more than 5%. Left ventricular response was not different between patients and control subjects. MR imaging is well suited to assess cardiac response to exercise, and findings revealed a decrease in PR and an abnormal RV response to exercise in patients with corrected tetralogy of Fallot.