title: Magnetic resonance imaging of constant total heart volume and center of mass in patients with functional single ventricle before and after staged Fontan procedure.
abstract: It has been previously demonstrated that total heart volume (contents of pericardium) throughout the cardiac cycle varies by < 5% and location of center of mass by < 3 mm. The hypothesis has thus developed that for maximal efficiency, the heart should expend minimal energy in displacing extracardiac structures by maintaining a constant intracycle total heart volume and center of mass. This is achieved in the normal heart mainly by a piston-like movement of the atrioventricular valve plane toward the ventricular apex. As this has never been studied in the single ventricle heart or at various stages of Fontan reconstruction, it is conceivable that these patients may not exhibit the constancy of total heart volume and location of center of mass, which may lead to a poor outcome in some. The total heart volume and center of mass relationship was therefore evaluated in 25 children (0.4 to 237 months) with functional single ventricles at all stages of Fontan reconstruction using multiphase, multislice spin-echo or cine-magnetic resonance imaging. No significant difference was seen in variation between total heart volume and maximal volume between patients before bilateral cavopulmonary anastomosis (hemiFontan) (5.1 +/- 2.9%), after hemiFontan (3.6 +/- 1.6%) and after Fontan (8.2 +/- 7.7%); however, in 4 of 10, 1 of 8 and 5 of 7 patients, respectively, the total heart volume varied by < 5%. Across surgical subgroups, significant differences were found in the center of mass displacement (total, anteroposterior and superoinferior planes) but not in directionality of displacement.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia.
authors.forename: M A
authors.initials: MA
authors.lastname: Fogel
authors.forename: P M
authors.initials: PM
authors.lastname: Weinberg
authors.forename: K E
authors.initials: KE
authors.lastname: Fellows
authors.forename: E A
authors.initials: EA
authors.lastname: Hoffman
mesh_terms: D000704:Analysis of Variance; D006348:Cardiac Surgical Procedures / Q000379:methods; D002306:Cardiac Volume; D002648:Child; D002675:Child, Preschool; D006330:Heart Defects, Congenital / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D006352:Heart Ventricles / Q000002:abnormalities* / Q000601:surgery; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007223:Infant; D016018:Least-Squares Analysis; D008279:Magnetic Resonance Imaging; D011446:Prospective Studies