Three-dimensional imaging of the aortic valve and aortic root with computed tomography: new standards in an era of transcatheter valve repair/implantation

A CT-based technique to predict optimal projection for self-expanding TAVI in patients with different aortic valve anatomies

Background

Optimal projection is essential for valve deployment during transcatheter aortic valve implantation (TAVI). The purpose of this study was to propose an approach to predict optimal projection in TAVI candidates with different aortic valve anatomies.

Methods

331 patients undergoing self-expanding TAVI were included and the so-called non-coronary cusp (NCC)-parallel technique was utilized, which generated the predicted projection by connecting NCC commissures on the transverse plane on the pre-procedural computed tomography images.

Results

37.8% of the study cohort were bicuspid aortic valve (BAV) patients. Around 80% of both NCC-parallel views and final views were in the right anterior oblique (RAO) and caudal (CAU) quadrant. There was less than 5° change required from the NCC-parallel view to the final implanted view in 79% of tricuspid aortic valve (TAV) patients but only in 27% (13/48) of type 0 BAV patients with coronary arteries originated from the different cusps. After excluding the above mentioned BAV patients, 62.3% (48/77) of BAV patients needed less than 5° change to achieve optimal projection and only in 8 patients, the angular change was larger than 10° in either left/right anterior oblique or cranial/caudal direction.

Conclusions

The NCC-parallel technique provides reliable prediction for optimal projection in self-expanding TAVI in all TAV and most BAV patients, with a vast majority of views in the RAO and CAU quadrant.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02387-7.

Systematic Approach to High Implantation of SAPIEN-3 Valve Achieves a Lower Rate of Conduction Abnormalities Including Pacemaker Implantation

BACKGROUND

The conventional method of implanting balloon-expandable SAPIEN-3 (S3) valve results in a final 70:30 or 80:20 ratio of the valve in the aorta:left ventricular outflow tract with published rates of permanent pacemaker around 10%. We sought to evaluate whether higher implantation of S3 reduces conduction abnormalities including the need for permanent pacemaker.

METHODS

We included consecutive patients who underwent transfemoral transcatheter aortic valve replacement using S3 between April 2015 and December 2018 and compared outcomes with typical valve deployment strategy to our more contemporary high deployment technique (HDT). We excluded patients with nontransfemoral access or valve-in-valve.

RESULTS

Among 1028 patients, HDT was performed in 406 patients (39.5%). Mean implantation depth under the noncoronary cusp was significantly smaller with HDT compared with conventional technique (1.5±1.6 versus 3.2±1.9 mm; P<0.001). Successful implantation was achieved in 100% of the patients in both groups with no cases of conversion to open heart surgery, second valve implantation within the first transcatheter aortic valve replacement, or coronary occlusion during transcatheter aortic valve replacement. One patient (0.2%) had valve embolization with HDT (P=0.216). Thirty-day permanent pacemaker rates were lower with HDT (5.5% versus 13.1%; P<0.001), as were rates of complete heart block (3.5% versus 11.2%; P<0.001) and new-onset left bundle branch block (5.3% versus 12.2%; P<0.001). There were no differences in mild (16.5% versus 15.9%; P=0.804), or moderate-to-severe aortic regurgitation (1% versus 2.7%; P=0.081) at 1 year. HDT was associated with slightly higher 1-year mean gradients (13.1±6.2 versus 11.8±4.9 mm Hg; P=0.042) and peak gradients (25±11.9 versus 22.5±9 mm Hg; P=0.026). However, Doppler velocity index was similar (0.47±0.15 versus 0.48±0.13; P=0.772).

CONCLUSIONS

Our novel technique for balloon-expandable S3 valve positioning consistently achieves higher implantation resulting in substantial reduction in conduction abnormalities and permanent pacemaker requirement after transcatheter aortic valve replacement without compromising procedural safety or valve hemodynamics. Operators should consider this as an important technique to improve patient outcomes.

Assessment of left ventricular outflow tract and aortic root: comparison of 2D and 3D transthoracic echocardiography with multidetector computed tomography

AIMS

Accurate echocardiographic assessment of left ventricular outflow tract (LVOT) and the aortic root is necessary for risk stratification and choice of appropriate treatment in patients with pathologies of the aortic valve and aortic root. Conventional 2D transthoracic echocardiographic (TTE) assessment is based on the assumption of a circular shaped LVOT and aortic root, although previous studies have indicated a more ellipsoid shape. 3D TTE and multidetector computed tomography (MDCT) applies planimetry and are not dependent on geometrical assumptions. The aim was to test accuracy, feasibility, and reproducibility of 3D TTE compared to 2D TTE assessment of LVOT and aortic root areas, with MDCT as reference.

METHODS AND RESULTS

We examined 51 patients with 2D/3D TTE and MDCT at the same day. All patients were re-examined with 2D/3D TTE on a different day to evaluate 2D and 3D re-test variability. Areas of LVOT, aortic annulus, and sinus were assessed using 2D, 3D TTE, and MDCT. Both 2D/3D TTE underestimated the areas compared to MDCT; however, 3D TTE areas were significantly closer to MDCT-areas. 2D vs. 3D mean MDCT-differences: LVOT 1.61 vs. 1.15 cm2, P = 0.019; aortic annulus 1.96 vs. 1.06 cm2, P < 0.001; aortic sinus 1.66 vs. 1.08 cm2, P = 0.015. Feasibility was 3D 76-79% and 2D 88-90%. LVOT and aortic annulus areas by 3D TTE had lowest variabilities; intraobserver coefficient of variation (CV) 9%, re-test variation CV 18-20%.

CONCLUSION

Estimation of LVOT and aortic root areas using 3D TTE is feasible, more precise and more accurate than 2D TTE.

Preprocedural three-dimensional planning aids in transcatheter ductal stent placement: A single-center experience

OBJECTIVES

Describe the use of three-dimensional (3D) patent ductus arteriosus (PDA) modeling to better define ductal anatomy to improve preprocedural planning for ductal stent placement.

BACKGROUND

Ductal stenting is an alternative to surgical shunting in patients with ductal dependent pulmonary blood flow. Ductal anatomy is often complex with extreme tortuosity and risk of pulmonary artery isolation, thus increasing procedural risks.

METHODS

CT angiograms were segmented to produce 3D PDA models. Ductal morphology was characterized with attention to access approach, degree of pulmonary artery offset/risk of isolation and ductal tortuosity. 3D models were retrospectively compared with biplane angiography.

RESULTS

3D modeling was performed in 12 patients with adequate image quality for complete analysis in 11; median (interquartile range) age/weight 17 days (8-20 days) and 3.1 kg (2.4-3.9 kg). The PDA was reverse oriented in nine with average length of 17.2 ± 2.5 mm and high tortuosity (mean tortuosity index 52, range 3-108). From 3D modeling, two patients were excluded from ductal stenting-extreme ductal tortuosity and threatened pulmonary artery discontinuity, respectively. Ductal stenting was successful in the remaining nine with no major procedural complications. 3D modeling predicted a successful access approach based on the aortic orientation of the ductus in all patients (five carotid, two axillary, two femoral). When comparing 2D angiography with 3D models, angiography consistently underestimated ductal length (-3.2 mm ± 1.6 mm) and tortuosity (-14.8 ± 7.2).

CONCLUSIONS

3D modeling prior to ductal stent placement for ductal dependent pulmonary blood flow is useful in procedural planning, specifically for eligibility, access approach, and accurate ductal measurements. Further studies are needed to determine if 3D planning improves procedural outcomes.

Validation of a low-dose contrast 64-slice cardiac computed tomography angiography protocol for aortic valve annulus sizing

Cardiac computed tomography angiography (CCTA) is the gold standard for accurately sizing the aortic valve annulus prior to aortic valve replacement. A reduction of contrast volume administered for CCTA, without sacrificing image quality, is desirable. Signal-to-noise ratio represents final CCTA image quality. Consecutive patients referred to CCTA for aortic valve annulus sizing were retrospectively analyzed. Patients were grouped into a low-dose contrast (LDCT) group and traditional dose contrast (TDCT) group. In the LDCT group, contrast dose was <50% of the maximal allowable dose (3.7 × estimated glomerular filtration rate). Guided by a time-density curve, the contrast was administered in a two-stage infusion, and retrospectively gated images were acquired with a 64-multidetector computed tomography scanner. Out of 123 patients (age 80 ± 9 years; 46% female), 65 (52.9%) underwent LDCT and 58 (47.2%) underwent TDCT. Contrast volume was significantly lower in the LDCT group (LDCT 41.2 ± 9.8 vs TDCT 76.2 ± 14.2 mL; P < 0.001). The signal-to-noise ratio of the aortic root was 10.4 ± 4.1 for the LDCT group and 8.4 ± 3.3 for the TDCT group (P = 0.004). Aortic root dimensions could be measured in both LDCT and TDCT groups. In conclusion, LDCT with 64-slice CCTA can effectively size the aortic valve annulus to direct aortic valve replacement while offering reduced contrast exposure.

Managing Stroke During Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement (TAVR) has become the default treatment option for high-risk patients with aortic stenosis and an alternative to surgical aortic valve replacement in intermediate-risk patients. There are, however, concerns regarding strokes during TAVR. Reported stroke rates vary strongly depending on the type of study, stroke definition, cohort and study period. Furthermore, stroke after TAVR occurs in three distinct phases: 1) early high-risk, directly procedure related; 2) elevated risk interval between day 2 and day 30; 3) late hazard interval. Each of these phases is caused by the different aetiologies of stroke. This review summarises the different aetiologies and potential strategies for managing stroke during TAVR.

Value of Image Fusion in Coronary Angiography for the Detection of Coronary Artery Bypass Grafts

BACKGROUND

Coronary angiography is more complex in patients with coronary artery bypass grafts (CABG). Image fusion is a new technology that allows the overlay of a computed tomography (CT) three-dimension (3D) model with fluoroscopic images in real time.

METHODS AND RESULTS

This single-center prospective study included 66 previous CABG patients undergoing coronary and bypass graft angiography. Image fusion coronary angiographies (fusion group, 20 patients) were compared to conventional coronary angiographies (control group, 46 patients). The fusion group included patients for whom a previous chest CT scan with contrast was available. For patients in this group, aorta and CABG were reconstructed in 3D from CT acquisitions and merged in real time with fluoroscopic images. The following parameters were compared: time needed to localize the CABG; procedure duration; air kerma (AK); dose area product (DAP); and volume of contrast media injected. Results are expressed as median. There were no significant differences between the 2 groups in patient demographics and procedure characteristics (access site, number of bypass to be found, and interventional cardiologist's experience). The time to localize CABG was significantly shorter in the fusion group (7.3 versus 12.4 minutes; P=0.002), as well as the procedure duration (20.6 versus 25.6 minutes; P=0.002), AK (610 versus 814 mGy; P=0.02), DAP (4390 versus 5922.5 cGy·cm(2); P=0.02), and volume of iodinated contrast media (85 versus 116 cc; P=0.002).

CONCLUSIONS

3D image fusion improves the CABG detection in coronary angiography and reduces the time necessary to localize CABG, total procedure time duration, radiation exposure, and volume of contrast media.

Peri-procedural imaging for transcatheter mitral valve replacement

Mitral regurgitation (MR) has a high prevalence in older patient populations of industrialized nations. Common etiologies are structural, degenerative MR and functional MR secondary to myocardial remodeling. Because of co-morbidities and associated high surgical risk, open surgical mitral repair/replacement is deferred in a significant percentage of patients. For these patients transcatheter repair/replacement are emerging as treatment options. Because of the lack of direct visualization, pre- and intra-procedural imaging is critical for these procedures. In this review, we summarize mitral valve anatomy, trans-catheter mitral valve replacement (TMVR) options, and imaging in the context of TMVR.

Recent developments in echocardiographic imaging

PURPOSE OF REVIEW

This review provides an outline of recent applications related to the use of ultrasonography in various catheter-based procedures for the repair of many valvular abnormalities.

RECENT FINDINGS

Percutaneous interventions are becoming a safe and effective therapeutic modality in the management of various valvular defects. The intrinsic ability of ultrasound to provide real-time accurate assessment of cardiac and valvular structural and functional abnormalities makes this modality distinctively useful in the execution of percutaneous valvular procedures and evaluation of their results.Clinical applications of myocardial deformation and cardiac mechanics have been investigated in an increasing number of clinical applications. Speckle tracking accurately measures myocardial deformation parameters and has been recently applied to the evaluation of mitral insufficiency mechanisms.

SUMMARY

Recent developments in echocardiography are promoting this modality from its traditional role of diagnostic technique into one suitable for aiding in the execution of complex catheter-based procedures and for accurate monitoring of therapeutic response in many clinical settings.

Imaging and minimally invasive aortic valve replacement

Cardiovascular imaging has been the most important tool allowing for innovation in cardiac surgery. There are now a variety of approaches available for treating aortic valve disease, including standard sternotomy, minimally invasive surgery, and percutaneous valve replacement. Minimally invasive cardiac surgery relies on maximizing exposure within a limited field of view. The complexity of this approach is increased as the relationship between the great vessels and the bony thorax varies between individuals. Ultimately, the success of minimally invasive surgery depends on appropriate choices regarding the type and location of the incision, cannulation approach, and cardioprotection strategy. These decisions are facilitated by preoperative imaging, which forms the focus of this review.

Multidimensional MDCT angiography in the context of transcatheter aortic valve implantation

OBJECTIVE

Transcatheter aortic valve implantation has emerged as a viable treatment alternative for patients with severe aortic stenosis who are not surgical candidates. Multidimensional (3D and 4D) MDCT angiography plays a critical role in the safety, success, and outcome of an institutional transcatheter aortic valve implantation program.

CONCLUSION

Given the increasing therapeutic role of this innovative technique, an understanding of essential imaging concepts in its context is critical for appropriate image acquisition and interpretation.

Aortic valve adaptation to aortic root dilatation: insights into the mechanism of functional aortic regurgitation from 3-dimensional cardiac computed tomography

BACKGROUND

The 3-dimensional relationship between aortic root and cusp is essential to understand the mechanism of aortic regurgitation (AR) because of aortic root dilatation (ARD). We sought to test the hypothesis that the stretched cusps in ARD enlarge to compensate for ARD.

METHODS AND RESULTS

Computed tomography imaged 92 patients (57 with ARD, 29 with moderate to severe AR, 28 without significant AR) and 35 normal controls. Specialized 3-dimensional software measured individual cusp surface areas relative to maximal mid-sinus cross-sectional area and minimal 3-dimensional annular area, coaptation area fraction, and asymmetry of sinus volumes and intercommissural distances. Total open cusp surface area increased (P<0.001) from 7.6±1.4 cm(2)/m(2) in normals to 12.9±2.2 cm(2)/m(2) in AR-negative and 15.2±3.3 cm(2)/m(2) in AR-positive patients. However, the ratio of closed cusp surface area to maximal mid-sinus area, reflecting cusp adaptation, decreased from normals to AR-negative to AR-positive patients (1.38±0.20, 1.15±0.15, 0.88±0.15; P<0.001), creating the lowest coaptation area fraction. Cusp distensibility (closed diastolic versus open area) decreased from 20% in controls and AR-negative patients to 5% in AR-positive patients (P<0.001). Multivariate determinants of AR and coaptation area fraction reflected both sinus size and cusp-to-annular adaptation. ARD was also progressively asymmetrical with root size, and individual cusp surface areas failed to match this asymmetry.

CONCLUSIONS

Aortic cusp enlargement occurs in ARD, but cusp adaptation and distensibility become limited in prominent, asymmetrical ARD, leading to AR. Optimal AR repair tailored to individual patient anatomy can benefit from appreciating valve adaptation and 3-dimensional relationships; understanding cusp adaptation mechanisms may ultimately provide therapeutic opportunities to improve such compensation.

[Investigation techniques and importance of CT for diagnostics of cardiac valvular diseases]

CLINICAL/METHODICAL ISSUE

Cardiac computed tomography (CT) is the first-line modality for coronary assessment. In addition valvular morphology and function can be evaluated.

STANDARD RADIOLOGICAL METHODS

The method of choice for the evaluation of cardiac valves is echocardiography, followed by magnetic resonance imaging.

METHODICAL INNOVATIONS

Recent technical improvements and advances in temporal resolution allow a detailed anatomical and functional evaluation of the cardiac valves.

PERFORMANCE

Cardiac CT provides an excellent image quality of the aortic and mitral valve thus enabling an evaluation of the morphology. In addition, cardiac CT allows an assessment of aortic valve function with respect to the grading of stenosis and regurgitation.

ACHIEVEMENTS

Cardiac CT is not considered the first-line modality for the evaluation of cardiac valves; however, beyond coronary assessment CT provides important information on the morphology and function of cardiac valves.

PRACTICAL RECOMMENDATIONS

Cardiac CT can be a useful imaging alternative for patients in whom other more commonly used methods, such as echocardiography and magnetic resonance imaging fail to provide the necessary information.

Aortic root geometry in patients with aortic stenosis assessed by real-time three-dimensional transesophageal echocardiography

BACKGROUND

The authors hypothesized that aortic root geometry is different between bicuspid and tricuspid aortic stenosis (AS) that can be assessed using real-time three-dimensional (3D) transesophageal echocardiography. The aims of this study were (1) to validate the accuracy of 3D transesophageal echocardiographic measurements of the aortic root against multidetector computed tomography as a reference, (2) to determine the difference of aortic root geometry between patients with tricuspid and bicuspid AS, and (3) to assess its impact on pressure recovery.

METHODS

In protocol 1, 3D transesophageal echocardiography and contrast-enhanced multidetector computed tomography were performed in 40 patients. Multiplanar reconstruction was used to measure the aortic annulus, the sinus of Valsalva, and the sinotubular junction area, as well as the distance and volume from the aortic annulus to the sinotubular junction. In protocol 2, the same 3D transesophageal echocardiographic measurements were performed in patients with tricuspid AS (n = 57) and bicuspid AS (n = 26) and in patients without AS (n = 32). The energy loss coefficient was also measured in patients with AS.

RESULTS

In protocol 1, excellent correlations of aortic root geometric parameters were noted between the two modalities. In protocol 2, compared with patients without AS, those with tricuspid AS had smaller both sinotubular junction areas and longitudinal distances, resulting in a 23% reduction of aortic root volume. In contrast, patients with bicuspid AS had larger transverse areas and longitudinal distances, resulting in a 30% increase in aortic root volume. The energy loss coefficient revealed more frequent reclassification from severe AS to moderate AS in patients with tricuspid AS (17%) compared with those with bicuspid AS (10%).

CONCLUSIONS

Three-dimensional transesophageal echocardiography successfully revealed different aortic root morphologies between tricuspid and bicuspid AS, which have different impacts on pressure recovery.

Standardized imaging for aortic annular sizing: implications for transcatheter valve selection

The safety and efficacy of transcatheter aortic valve replacement procedures are directly related to proper imaging. This report revisits the existing noninvasive and invasive approaches that have concurrently evolved to meet the demands for optimal selection and guidance of patients undergoing transcatheter aortic valve replacement. The authors summarize the published evidence and discuss the strengths and pitfalls of echocardiographic, computed tomographic, and calibrated aortic balloon valvuloplasty techniques in sizing the aortic valve annulus. Specific proposals for 3-dimensional tomographic reconstructions of complex 3-dimensional aortic root anatomy are provided for reducing intermodality variability in annular sizing. Finally, on the basis of the sizing approaches discussed in this review, the authors provide practical recommendations for balloon-expandable and self-expandable prostheses selection. Strategic use of echocardiographic, multislice computed tomographic, and angiographic data may provide complementary information for determining the anatomical suitability, efficacy, and safety of the procedure.

Value of cardiac CT in comprehensive aortic valve and root evaluation before percutaneous aortic valve replacement

BACKGROUND

Aortic stenosis (AS) is the most frequent valvular heart disease, and patients who develop AS are at a high risk of sudden death. There is no medical cure available, and aortic valve replacement is the only effective treatment for advanced disease. Preoperative evaluation is the cornerstone of therapy and is necessary for selecting the implantation technique and valve.

PURPOSE

To evaluate the role of cardiac CT in comprehensive aortic valve and aortic root evaluation before percutaneous aortic valve replacement.

MATERIAL AND METHODS

Thirty-four patients with severe aortic valve stenosis were evaluated by cardiac CT. The aortic valve calcification grade defined by cardiac CT was compared to the operative findings. The mean calculated aortic annulus diameter (CAAD) measured by cardiac CT was compared to the aortic annulus diameter measured by transthoracic echocardiography (TTE) as well as during the operation. The distances from the aortic valve annulus to the coronary ostia (right and left) were measured by cardiac CT and compared to the intraoperative measurements. The findings from the CT coronary angiography and conventional coronary angiography were compared.

RESULTS

There was strong agreement (k = 0.865) between the calcification grade by cardiac CT and the intraoperative grading. There was a stronger correlation (r = 0.948) between the CAAD assessed by cardiac CT and intraoperatively compared to the correlation between the intraoperative versus TTE measurements (r = 0.660). The distances measured between the aortic annulus and the right and left coronary artery ostia by cardiac CT were strongly correlated with the distances measured intraoperatively (r = 0.966 and 0.940 in the right and left sides, respectively). Cardiac CT detected three coronary artery stenotic lesions and three patent stents. All findings were confirmed by conventional coronary angiography. Thirteen percent of the evaluated coronary artery segments were of non-diagnostic quality by cardiac CT.

CONCLUSION

Cardiac CT substantially facilitates the assessment of aortic root morphology prior to aortic valve replacement.

The clinical anatomy and pathology of the human arterial valves: implications for repair or replacement

A thorough understanding of valvar anatomy is essential for design engineers and clinicians in the development and/or employment of improved technologies or therapies for treating valvar pathologies. There are two arterial valves in the human heart--pulmonary and aortic valves. Both are complex structures whose normal anatomical components can vary greatly between individuals. We discuss the anatomy, pathology, and challenges relating to transcatheter and surgical repair/replacement of the arterial valves in a translational manner. The high prevalence of aortic valvar pathologies in the burgeoning elderly population, coupled with poor clinical outcomes for patients who go untreated, has resulted in prolific spending in the research and development of more effective and less traumatic therapies. The accelerated development of therapies for treating arterial valves has been guided by anatomical information gathered from high-resolution imaging technologies, which have focused attention on the need for complete understanding of arterial valvar clinical anatomies. This article is part of a JCTR special issue on Cardiac Anatomy.

Cardiac imaging in valvular heart disease

The aim of this article is to provide a perspective on the relative importance and contribution of different imaging modalities in patients with valvular heart disease. Valvular heart disease is increasing in prevalence across Europe, at a time when the clinical ability of physicians to diagnose and assess severity is declining. Increasing reliance is placed on echocardiography, which is the mainstay of cardiac imaging in valvular heart disease. This article outlines the techniques used in this context and their limitations, identifying areas in which dynamic imaging with cardiovascular magnetic resonance and multislice CT are expanding.

A general three-dimensional parametric geometry of the native aortic valve and root for biomechanical modeling

The complex three-dimensional (3D) geometry of the native tricuspid aortic valve (AV) is represented by select parametric curves allowing for a general construction and representation of the 3D-AV structure including the cusps, commissures and sinuses. The proposed general mathematical description is performed by using three independent parametric curves, two for the cusp and one for the sinuses. These curves are used to generate different surfaces that form the structure of the AV. Additional dependent curves are also generated and utilized in this process, such as the joint curve between the cusps and the sinuses. The model's feasibility to generate patient-specific parametric geometry is examined against 3D-transesophageal echocardiogram (3D-TEE) measurements from a non-pathological AV. Computational finite-element (FE) mesh can then be easily constructed from these surfaces. Examples are given for constructing several 3D-AV geometries by estimating the needed parameters from echocardiographic measurements. The average distance (error) between the calculated geometry and the 3D-TEE measurements was only 0.78±0.63mm. The proposed general 3D parametric method is very effective in quantitatively representing a wide range of native AV structures, with and without pathology. It can also facilitate a methodical quantitative investigation over the effect of pathology and mechanical loading on these major AV parameters.

Comparison of aortic root measurements in patients undergoing transapical aortic valve implantation (TA-AVI) using three-dimensional rotational angiography (3D-RA) and multislice computed tomography (MSCT): differences and variability

To evaluate for the first time the degree of compliance between conventional multislice computed tomography (MSCT) and three-dimensional rotational angiography (3D-RA) in measuring relevant dimensions of the aortic annulus, the aortic root and the thoracic aorta in patients undergoing TA-AVI. Twenty-seven patients (82 ± 11 years) with severe aortic stenosis received contrast enhanced ECG gated MSCT prior to TA-AVI and intra-procedural rotational angiography. The aortic annulus size, the distance to the coronary ostia and diameters of the aortic root and the thoracic aorta were measured with both methods by two observers blinded to each other. Linear regression and Bland-Altman analysis were performed to determine the degree of compliance between both methods. The limits of agreement were within two standard deviations for all measurements and with high correlation especially for the supra-annular dimensions. Sizing of the aortic annulus revealed lower interobserver variability for MSCT than for 3D-RA with a maximum deviation of 2.1 ± 2.5 and 1.7 ± 2.8 mm for diameter measurements and for the effective diameter, respectively. With current protocols intra-procedural 3D-RA provides good image quality especially for structures above the aortic annulus. Due to a lower interobserver variability in sizing the aortic annulus MSCT remains more suitable for aortic root assessment prior to TA-AVI.

Low radiation dose non-contrast cardiac CT: is it of value in the evaluation of mechanical aortic valve

BACKGROUND

Prosthetic bileaflet mechanical valve function has been traditionally evaluated using echocardiography and fluoroscopy. Multidetector computed tomography (MDCT) is a novel technique for cardiac evaluation.

PURPOSE

To evaluate bileaflet mechanical aortic valves using a low-milliampere (mA), non-contrast MDCT protocol with a limited scan range.

MATERIAL AND METHODS

Forty patients with a bileaflet mechanical aortic valve were evaluated using a non-contrast, low-mA, ECG-gated 64 MDCT protocol with a limited scan range. MDCT findings of opening and closing valve angles were correlated to fluoroscopy and echocardiography. Also, the valve visibility was evaluated on MDCT and fluoroscopy according to a 3-point grading scale.

RESULTS

The visualization score with the MDCT was significantly superior to the fluoroscopy (3 vs. 2.7). A strong correlation was noted between the opening (r = 0.82) and closing (r = 0.96) valve angles with MDCT and fluoroscopy without a statistically significant difference (P = 0.31 and 0.16, respectively). The mean effective radiation dose of the suggested protocol was 4 ± 0.5 mSv. Five valves were evaluated using transesophageal echocardiography because the valves were difficult to evaluate with transthoracic echocardiography, and all of these valves were evaluated optimally with MDCT. A high-pressure gradient was noted in nine valves, and the MDCT showed that seven of these valves inadequately opened, and two valves opened well, which resulted in patient valve mismatch. Incomplete valve closure was noted in five valves, and the echocardiography showed significant transvalvular regurgitation in all five valves.

CONCLUSION

MDCT can provide a precise measurement of valve function and can potentially evaluate high-pressure gradients and transvalvular regurgitation.

Cardiovascular magnetic resonance for the assessment of patients undergoing transcatheter aortic valve implantation: a pilot study

BACKGROUND

Before trans-catheter aortic valve implantation (TAVI), assessment of cardiac function and accurate measurement of the aortic root are key to determine the correct size and type of the prosthesis. The aim of this study was to compare cardiovascular magnetic resonance (CMR) and trans-thoracic echocardiography (TTE) for the assessment of aortic valve measurements and left ventricular function in high-risk elderly patients submitted to TAVI.

METHODS

Consecutive patients with severe aortic stenosis and contraindications for surgical aortic valve replacement were screened from April 2009 to January 2011 and imaged with TTE and CMR.

RESULTS

Patients who underwent both TTE and CMR (n = 49) had a mean age of 80.8 ± 4.8 years and a mean logistic EuroSCORE of 14.9 ± 9.3%. There was a good correlation between TTE and CMR in terms of annulus size (R2 = 0.48, p < 0.001), left ventricular outflow tract (LVOT) diameter (R2 = 0.62, p < 0.001) and left ventricular ejection fraction (LVEF) (R2 = 0.47, p < 0.001) and a moderate correlation in terms of aortic valve area (AVA) (R2 = 0.24, p < 0.001). CMR generally tended to report larger values than TTE for all measurements. The Bland-Altman test indicated that the 95% limits of agreement between TTE and CMR ranged from -5.6 mm to + 1.0 mm for annulus size, from -0.45 mm to + 0.25 mm for LVOT, from -0.45 mm2 to + 0.25 mm2 for AVA and from -29.2% to 13.2% for LVEF.

CONCLUSIONS

In elderly patients candidates to TAVI, CMR represents a viable complement to transthoracic echocardiography.

[Multislice computed tomography in the selection of candidates for transcatheter aortic valve implantation]

Transcatheter aortic valve implantation is an emerging treatment option for severe symptomatic aortic stenosis in patients considered unsuitable for surgical valve replacement. The authors review the use of multislice computed tomography in the selection of candidates for transcatheter aortic valve replacement, procedural support and post-interventional follow-up. A single-center experience of the role of this imaging technique is also described. Multislice computed tomography is an essential imaging tool in the selection and exclusion of candidates for transcatheter aortic valve implantation, providing evaluation of coronary anatomy and the relationship of the coronary ostia with the aortic valve structure, and accurate analysis of the valve annulus and aortic root, left ventricular outflow tract, aorta and peripheral vascular access routes. Multislice computed tomography is also central to the choice of appropriate prosthesis size. In addition, it guides arterial puncture by image fusion techniques and enables correct prosthesis apposition to be verified. This review aims to describe the role of computed tomography in this increasingly common interventional valve procedure, providing an overview of current knowledge and applications.

Cardiac CT: practical approach to integrate appropriate indications in daily practice

Recent advances in CT technologies had significantly improved the clinical utility of cardiac CT. Major efforts have been made to optimize the image quality, standardize protocols and limit the radiation exposure. Rapid progress in post-processing tools dedicated not only to the coronary artery assessment but also to the cardiac cavities, valves and veins extended applications of cardiac CT. This potential might be however used optimally considering the current appropriate indications for use as well as the current technical imitations. Coronary artery disease and related ischemic cardiomyopathy remain the major applications of cardiac CT and at the same time the most complex one. Integration of a specific knowledge is mandatory for optimal use in this area for asymptomatic as for symptomatic patients, with a specific regards to patient with acute chest pain. This review aimed to propose a practical approach to implement appropriate indications in our routine practice. Emerging indications and future direction are also discussed. Adequate preparation of the patient, training of physicians, and the multidisciplinary interaction between actors are the key of successful implementation of cardiac CT in daily practice.