Leftventricular geometry ininfants with d-transposition ofthegreatarteries andintact interventricular septum

Theprolate ellipsoid geometryoftheleft ventricle withnormally related greatarteries minimizes wall tension andfunctionally commits theventricular septumtothesystemic ventricle. Age- andpressure-dependent changes inangiographically determined left ventricular volumeandmass measurements havebeenreported inpatients withd-transposition ofthegreatarteries andintact interventricular septum.Theobjective ofthis study was toevaluate thechanges inleft ventricular geometryinthis lesion during infancy bymeans ofsubxiphoid two-dimensional echocardiography. Leftventricular geometryinthetransverse equatorial plane oftheventricle was evaluated in19 neonates within 24hrofinitial cardiac catheterization, in16of19within 24hrofcardiac catheteriza- tion before performance ofSenning's- procedure, andinfive of19after postoperative catheterization. Ventricular geometry wasqualitatively evaluated according toventricular septal orientation andquanti- tatively bycorrelation oftheleft andright ventricular systolic pressureratio withthetransverse minor axis ratio. Qualitative changes inleft ventricular geometry during infancy andafter intra-atrial baffle procedure were demonstrated bysubxiphoid two-dimensional echocardiography. Theend-systolic transverse minoraxis ratio showedsignificant correlation (r = .58, p < .001) withthepeaksystolic pressureratio. Theevolution ofdynamic left ventricular outflow stenosis inpatients withd-transposi- tion ofthegreat arteries andintact interventricular septum was related to,butnotsolely determined by, theprogressive change inleft ventricular geometry. Changes inleft ventricular geometry ind-transpo- sition ofthegreat arteries withintact ventricular septum may havefunctional implications regarding angiographic volumedeterminations andtiming ofarterial "switch" procedures. Circulation 68,No.4,733-739, 1983. THESYSTEMICLEFTVENTRICLEisaprolate el- lipsoid withcircular geometry inthetransverse equato- rial plane.' 2Thisconfiguration minimizes wallten- sionandfunctionally commitstheinterventricular septum(IVS) totheleft ventricle.3 Two-dimensional echocardiography hasdemonstrated changes inleft ventricular geometry caused byvolume overload ofthe right ventricle.4 Pressure-dependent