***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background The preoperative evaluation of aortic root diameters is important for determining the surgical strategy in patients with aortic valve disease . The purpose of this study was to evaluate the usefulness of real-time three-dimensional echocardiography ( 3D-echo ) for the evaluation of aortic root diameters compared with two-dimensional echocardiography ( 2D-echo ) and to evaluate aortic root dynamics . Methods We prospect ively investigated 23 patients with aortic stenosis ( AS ) and 37 normal controls . With 2D-echo , aortic root diameters were measured from the parasternal long-axis view . With 3D-echo , long-axis and short-axis views of the aortic root were reconstructed from the full-volume image , and aortic root diameters were measured at mid-systole , end-systole , mid-diastole , and end-diastole . These aortic root diameters were compared between 2D and 3D measurements , regarding intraoperative and computed tomographic measurements as the gold st and ard . In addition , dynamic changes of aortic root diameters during a cardiac cycle were evaluated . Results Aortic root diameters measured by 3D-echo were larger than those measured by 2D-echo ( annular diameter 19.6 ± 2.1 vs. 21.2 ± 2.2 mm , p < 0.0001 ) , and 3D measurements were closer to intraoperative and computed tomographic measurements than 2D measurements . The diameter of the aortic annulus increased during diastole , but the changes during a cardiac cycle were significantly smaller in patients with AS than in normal controls ( 2.0 ± 2.2 vs. 7.8 ± 3.4 % , p < 0.0001 ) . Conclusions Aortic root diameters can be more accurately measured by 3D-echo than 2D-echo  . Dynamic change of the aortic annulus during a cardiac cycle was smaller in patients with AS . 3D-echo is useful for the quantitative evaluation of the aortic root , including dynamics during a cardiac cycle OBJECTIVES We sought to compare 3 methods of measurements of the aortic annulus , transthoracic echocardiography ( TTE ) , transesophageal echocardiography ( TEE ) , and multislice computed tomography ( MSCT ) , and to evaluate their potential clinical impact on transcatheter aortic valve implantation ( TAVI ) strategy . BACKGROUND Exact measurement of the aortic annulus is critical for a patient 's selection and successful implantation . METHODS Annulus diameter was measured using TTE , TEE , and MSCT in 45 consecutive patients with severe aortic stenosis referred for TAVI .  The TAVI strategy ( decision to implant and choice of the prosthesis ' size ) was based on manufacturer 's recommendations ( Edwards-Sapien prosthesis , Edwards Lifesciences , Inc. , Irvine , California ) . RESULTS Correlations between methods were good but the difference between MSCT and TTE ( 1.22 + /- 1.3 mm ) or TEE ( 1.52 + /- 1.1 mm ) was larger than the difference between TTE and TEE ( 0.6 + /- 0.8 mm ; p = 0.03 and p < 0.0001 , respectively ) . Regarding TAVI strategy , agreement between TTE and TEE overall was good ( kappa = 0.68 ) , but TAVI strategy would have been different in 8 patients ( 17 % ) . Agreement between MSCT and TTE or TEE was only modest ( kappa = 0.28 and 0.27 ) , and a decision based on MSCT measurements would have modified the TAVI strategy in a large number of patients ( 40 % to 42 % ) . Implantation , performed in 34 patients ( 76 % ) based on TEE measurements , was successful in all but 1 patient with grade 3/4 regurgitation . CONCLUSIONS In patients referred for TAVI , measurements of the aortic annulus using TTE , TEE , and MSCT were close but not identical , and the method used has important potential clinical implication s on TAVI strategy . In the absence of a gold st and ard , a strategy based on TEE measurements provided good clinical results BACKGROUND Precise evaluation of the aortic root geometry prior to transcatheter aortic valve implantation is important for procedural success in patients with aortic stenosis ( AS ) . To determine the potential for 3-dimensional transesophageal echocardiography ( 3DTEE ) , the aims of the present study were : ( 1 ) to assess the accuracy of 3DTEE measurements of the aortic root using multidetector computed tomography ( MDCT ) as a reference , and ( 2 ) to examine whether aortic root geometry differs between patients with and without AS . METHODS AND RESULTS 3DTEE and contrast-enhanced MDCT were performed in 35 patients . Multiplanar reconstruction was used to measure the left ventricular outflow tract ( LVOT ) and aortic annulus diameter/area , aortic valve area ( AVA ) , and distances between the annulus and coronary artery ostium . The same 3DTEE measurements were performed in patients with ( n=71 ) and without AS ( n=80 ) . Aortic annular and LVOT areas measured by 3DTEE were slightly but significantly smaller compared with values obtained with MDCT . Both methods revealed that the aortic annulus and LVOT have an oval shape . Aortic annular and LVOT area , AVA and the distances between the aortic annulus and the coronary ostia correlated well between the 2 modalities . Only minor differences in aortic root geometry were observed between patients with AS and those without . CONCLUSIONS The geometry of the aortic annulus can be reliably evaluated using 3DTEE as an alternative to MDCT for the assessment of aortic root OBJECTIVES The precise sizing of the aortic annulus is crucial in order to select the most appropriate valve size for  transcatheter aortic valve implantation ( TAVI ) .  Owing to the closed heart situation in TAVI , sizing has to be performed based on preoperative imaging when compared with direct sizing during conventional procedures . The aim of the study was to evaluate valve sizing performed either by CT-scan or by echocardiography by comparing these imaging-based measurements with direct intraoperative sizing . METHODS Prior to the st and ard conventional aortic valve replacement , 26 patients underwent cardiac CT-scan and echocardiographic examination .  Maximal annular diameter was measured by echocardiography at end-diastole and end-systole , including the leaflet calcifications . The CT-scan maximal , minimal and mean diameters were measured as well as the ' effective ' diameter ( CT(eff ) ) . CT(eff ) represents the diameter of a circle with the exact same area as the measured area of the annular circumference reconstructed from the CT- data set . Direct intraoperative diameters were measured after decalcification using metric sizers . RESULTS CT(eff ) and end-systolic echocardiographic diameters showed best agreement with intraoperative direct sizing ( intraop ) in the Bl and -Altman analysis [ mean difference for transoesophageal echocardiography ( TEE ) vs intraop 0.5 mm ( limits of agreement -2.5 - 3.5 ) ; mean difference for transthoracic echocardiography ( TTE ) vs intraop 0.38 mm ( limits of agreement -3.28 - 4.03 ) and CT(eff ) vs intraop -0.56 ( limits of agreement -3.16 - 2.05 ) ] . In patients with an oval-shaped annulus , CT(eff ) demonstrated the best agreement with intraop [ mean difference -0.32 ( limits of agreement -2.29 to 1.66 ) ] . CONCLUSIONS Both the ' effective ' CT diameter and end-systolic TEE values are the most reliable approaches for preoperative aortic annulus sizing . In patients with a pronounced oval-shaped annulus , the ' effective ' CT diameter seems to be the method of choice . Therefore , aortic annulus measurement using ' effective ' CT diameters should be included into current recommendations for TAVI sizing AIMS Accurate measurement of left ventricular outflow tract diameter ( LVOTd ) is essential for reliable estimation of aortic valve area ( AVA ) using the continuity equation . Transesophageal echocardiography ( TEE ) can accurately delineate the LVOT . The aim of this study was to assess the accuracy and reproducibility of LVOTd measurement using transthoracic echocardiography ( TTE ) with harmonic imaging when compared with TEE , in both systole and diastole . METHODS AND RESULTS We prospect ively studied 50 patients [ 20 with aortic stenosis ( AS ) and 30 without AS ] .  LVOTd was measured offline in a blinded fashion in both systole and diastole by two experienced observers using TTE in the parasternal long axis view and TEE in the mid-oesophageal aortic view ( approximately 130 degrees ) . There was strong correlation between TTE and TEE ( r=0.91 ) . LVOTd was slightly smaller by TTE when compared with TEE ( 2.11+/-0.21 vs. 2.16+/-0.22 cm , mean difference -0.05+/-0.09 cm , P=0.0003 ) . Compared with TEE , 95 % ( 2SD ) of LVOTd measurements by TTE were within + 0.14 and -0.24 cm . Inter- and intra-observer variability for LVOTd was 4.8+/-4.1 and 2.8+/-1.9 % for TTE and 4.2+/-3.1 and 2.5+/-1.6 % for TEE ( P=0.4 and 0.6 ) . In patients with AS , estimated AVA was 0.93+/-0.22 cm(2 ) using TTE and 0.96+/-0.24 cm(2 ) using TEE , P=0.08 . Diastolic LVOTd by TEE was slightly smaller compared with systolic LVOTd by TEE ( -0.03+/-0.07 cm , P=0.0005 ) , and there was strong correlation between the two ( r=0.95 ) . CONCLUSION We present the data regarding accuracy and reproducibility of LVOTd measurements by TTE when compared with TEE . LVOTd measurements at end-diastole may be helpful when systolic images are suboptimal BACKGROUND Computed tomography ( CT ) annular measurements are predictive of paravalvular regurgitation after  transcatheter aortic valve replacement ( TAVR ) which is a predictor of mortality and morbidity . OBJECTIVES To demonstrate the rationale and potential implication s of new CT sizing recommendations for TAVR . METHODS The CT sizing recommendations aim to ensure routine transcatheter heart valve ( THV ) oversizing of the aortic annular area [ ( THV external area/systolic annular area - 1 ) × 100 ; range , 1%-20 % ; target , 10%-15 % ] . Consecutive patients ( n = 120 ) underwent CT before TAVR with balloon-exp and able valves sized by transesophageal echocardiography ( TEE ) . Retrospectively , the CT-recommended THV size was compared with the actual size implanted . RESULTS Compared with TEE , application of the newly developed CT-based sizing recommendations would have led to implantation of a larger valve in 33.3 % ( 40/120 ) , no change in valve size in 55.8 % ( 67/120 ) , and a smaller valve in 10.8 % ( 13/120 ) . In patients when CT recommended a larger valve , the incidence of at least moderate paravalvular regurgitation was 25 % ( 10/40 ) compared with 4.5 % ( 3/67 ; P < 0.01 ) when both TEE and CT recommendations were in agreement . Using diastolic versus systolic CT measurements results in 20 % of patients receiving smaller THVs . TEE sizing result ed in 33.3 % ( 40/120 ) of valves being undersized ( THV area < CT systolic annular area ) with a mean annular oversizing of 9.4 % ± 17.4 % ( range : -21.5 % to 65.9 % ) without annular rupture . In contrast , the CT sizing recommendations results in mean annular oversizing of 13.9 % ± 8.0 % ( range , 1.3%-29.8 % ) . CONCLUSION These CT sizing recommendations enable st and ardized moderate overexpansion of the aortic annulus . Clinical outcomes from these recommendations are being prospect ively assessed in a multicenter trial BACKGROUND Accurate evaluation of aortic root geometry is necessary in congenital aortic valve lesions in children , to guide surgical or angiographical intervention . AIM To compare aortic annulus diameters measured by two- and three-dimensional transthoracic echocardiography ( 2D- and 3D-TTE ) , to determine the feasibility and reproducibility of 3D imaging and assess the dynamic changes during the cardiac cycle . METHODS Thirty children without heart disease were prospect ively included . Two orthogonal aortic annulus diameters were measured offline using multiplanar reconstruction in diastole and in systole and were compared with the measurement of the aortic annulus diameter by 2D-TTE . RESULTS Mean age was 11±3.6 years . Feasibility of 3D imaging was 100 % . The coefficients of intra- and interobserver variability were  
    Output:
    
Whereas the annular long-axis diameter showed insignificant change throughout the cycle , the short-axis diameter , area , and perimeter were significantly larger in systole compared with diastole .
Hence , the aortic annulus does undergo dynamic changes during the cardiac cycle .
In patients with large conformational changes , diastolic compared with systolic measurements can result in undersizing TAVI prostheses .