Assessment Of Global And Regional Torsion Of Anatomic Left Ventricle In Patients After The Arteries Switch Operation By Speckle Tracking Imaging

Complete transposition is the most common form of cyanotic congenital heartdisease that presents in a neonate (second most frequent overall). Abnormal septationof the truncus arteriosus results in connection of the pulmonary artery to the leftventricle and of the aorta to the right ventricle. These babies uniformly are cyanotic,although they may not be in distress while the PDA and foramen ovale provideadequate mixing of the venous flow streams. This condition creates two circulationsin parallel, with systemic venous blood being returned to the aorta and pulmonaryvenous flow being directed back to the pulmonary arteries. Echocardiography plays avital role in diagnosing it. An atrial septal defect is present in most patients. The sizeand direction of the interatrial shunt can be assessed with Doppler techniques.Coronary artery anomalies are present in more than one-third of patients. Detectionrequires careful recording of the ostia. Ventricular function and size are importantparameters that should also be assessed with echocardiography. Approximatelyone-third of patients with transposition have a ventricular septal defect，since venousadmixing is adequate in these patients, it’s not easy to detect until they have keyfeatures of pulmonary hypertension. In this case, subjects with significant rightventricular hypertension were excluded from evaluation of ventricular performancebecause of the associated left-ward septal displacement and consequent abnormal leftventricular configuration under these circumstances.The evaluation of patients after surgical correction of transposition relies heavilyon echocardiographic techniques. Two distinct surgical procedures have beenperformed for treatment of this condition. In the past, the most common form ofpalliation for transposition was an intraatrial baffle (also known as a Mustard,Senning, or atrial switch) procedure. The arterial switch procedure is currently thestandard approach for anatomic correction of transposition. This method has several practical and theoretic advantages over the intraatrial baffle procedure and has nowbecome the operation of choice in most situations. The procedure involves transectionof both great arteries and reanastomosis of the pulmonary artery to the right ventricleand the aorta to the left ventricle. Thus, the normal structure-function relationships ofthe ventricles are restored. Echocardiographic evaluation after the arterial switchprocedure should focus on assessment of left and right ventricular function and thedetection of any newly created structural problems, either involving the ventricles, thegreat artery anastomoses, or the origin of the coronary arteries.The recent developed2-dimensional (2D) speckle tracking imaging (STI)ultrasound has been proved useful to evaluate LV torsional deformation noninvasivelywith validation and detect subclinical cardiac dysfunctions in several congenital heartdefects. The aim of this study was to assess left ventricular rotation and twist inpatients with transposition of great arteries with intact ventricular septum (TGA/IVS)before and within five years after the arterial switch operation (ASO)， andabnormalities can be detected earlier combined with traditional indexes of leftventricular function.This paper is to assess the global and regional left ventricular torsion in15patients with TGA/IVS before and two or three weeks after ASO using2D-STI. Basaland apical short-axis images were acquired to obtain LV twist versus time profiles andanalyze rotation of6segments and the peak twist, time to peak twist at each plane.We compared these indexes between groups. In addition,25(age range,0.5–60months) patients who successfully underwent ASO repair were followed up toevaluate LV twist and untwisting. They were divided into early and late categories(older than half a year) according to examined age. The LV peak systolic torsionand systolic twisting and diastolic untwisting velocities were determined bySTI. The difference between postoperative groups and corresponding control groupswere observe and the relationship between peak untwisting velocity and septal e’ inthose groups were also analysised. Results①Compared with pre-operation, the wall thickness (SWTd and PWTd) in thepostoperative group was significantly higher（P<0.01）,giving rise to elevatedRWT(P<0.01) although it was lower before operation（P<0.05）,besides RWTcorrelated positive with age at operation（r=0.73,p=0.004）.②The peak E and A velocity were higher before operation while e′was lowerresulting in raised E/e’. After the operation, both mitral inflow velocities fellespecially A wave and e’ continued to decline. EF value in preoperative groupwas higher than that in postoperative group and control group.③Seen from the apex level，the subpulmonary left ventricle performed almost thesame wringing motion as the normal LV that with clockwise rotation at the baseand counter clockwise rotation at the apex. The apical and basal rotation, peaktwist and time to peak twist were similar between them (P>0.05). The peakapical rotation in postoperative group was significantly depressed compared withpreoperative group (P<0.01) while basal and global parameters were similar(P>0.05).④Compared with controls, patients had a notably higher regional rotation ofanterior and anteroseptal segments at basal level before operation (all P<0.05)but reduced apical rotation of inferoseptal, inferior and posterior wall afteroperation (all P<0.01).⑤LV peak apical rotation (P=0.01), twist (P=0.02) and peak untwisting velocity(PUV)(P=0.001) were lower in patients early after the operation than incorresponding control group.⑥No significant difference in LV twisting and untwisting was noted between thelater group and control2(P>0.05).⑦For the normal younger group(control1), PUV correlated positively withe’(r=0.68, p<0.001),however, there were no significant relationship betweenPUV and e’ in younger patient group and older age group(older patient group and control2).Conclusions⑴Rotation was relatively inhomogenous both in pre-and postoperative patients withTGA/IVS. Basal rotation being greatest in the anteroseptal and anterior wall in thepreoperative group may be a compensatory behavior to maintain contractileproperties. Apical rotation being lowest in the posterior, inferior andposteriorseptal wall might be the reason of myocardial ischemia during theoperation. The anatomic LV is prone to being concentric remodeling whichdespairs LV filling, and it will become obvious when the operation time is delayed.However, this trend can be overcome after operation if operated in time.⑵Two dimensional speckle tracking echocardiography may sensitively detectimpaired LV torsional mechanics in patients with TGA/IVS early after ASO, andthe impairment of LV relaxation leads to increased LV filling pressure which isconsistent with higher E/e’. However, patients recovered well thereafter and theoverall midterm outcome of ASO is satisfying.