Feasibility of Reduced Iodine Loads for Vascular Assessment Prior to Transcatheter Aortic Valve Implantation (TAVI) Using Spectral Detector CT

Reduced iodine loads for computed tomography (CT)-based vascular assessment prior to transcatheter aortic valve implantation (TAVI) may be feasible in conjunction with a spectral detector CT scanner. This prospective single-center study considered 100 consecutive patients clinically referred for pre-TAVI CT. They were examined on a dual-layer detector CT scanner to obtain an ECG-gated cardiac scan and a non-ECG-gated aortoiliofemoral scan. Either a standard contrast media (SCM) protocol using 80 mL Iohexol 350 mgI/mL (iodine load: 28 gI) or a body-mass-index adjusted reduced contrast media (RCM) protocol using 40-70 mL Iohexol 350 mgI/mL (iodine load: 14-24.5 gI) were employed. Conventional images and virtual monoenergetic images at 40-80 keV were reconstructed. A threshold of 250 HU was set for sufficient attenuation along the arterial access pathway. A qualitative assessment used a five-point Likert scale. Sufficient attenuation in the thoracic aorta was observed for all patients in both groups using conventional images. In the abdominal, iliac, and femoral segments, sufficient attenuation was observed for the majority of patients when using virtual monoenergetic images (SCM: 96-100% of patients, RCM: 88-94%) without statistical difference between both groups. Segments with attenuation measurements below the threshold remained qualitatively assessable as well. Likert scores were 'excellent' for virtual monoenergetic images 50 keV and 55 keV in both groups (RCM: 1.2-1.4, SCM: 1.2-1.3). With diagnostic image quality maintained, it can be concluded that reduced iodine loads of 14-24.5 gI are feasible for pre-TAVI vascular assessment on a spectral detector CT scanner.

The Feasibility of Deep Learning-Based Reconstruction for Low-Tube-Voltage CT Angiography for Transcatheter Aortic Valve Implantation

OBJECTIVE

The purpose of this study is to evaluate the efficacy of deep learning reconstruction (DLR) on low-tube-voltage computed tomographic angiography (CTA) for transcatheter aortic valve implantation (TAVI).

METHODS

We enrolled 30 patients who underwent TAVI-CT on a 320-row CT scanner. Electrocardiogram-gated coronary CTA (CCTA) was performed at 100 kV, followed by nongated aortoiliac CTA at 80 kV using a single bolus of contrast material. We used hybrid-iterative reconstruction (HIR), model-based IR (MBIR), and DLR to reconstruct these images. The contrast-to-noise ratios (CNRs) were calculated. Five-point scales were used for the overall image quality analysis. The diameter of the aortic annulus was measured in each reconstructed image, and we compared the interobserver and intraobserver agreements.

RESULTS

In the CCTA, the CNR and image quality score for DLR were significantly higher than those for HIR and MBIR ( P < 0.01). In the aortoiliac CTA, the CNR for DLR was significantly higher than that for HIR ( P < 0.01) and significantly lower than that for MBIR ( P ≤ 0.02). The image quality score for DLR was significantly higher than that for HIR ( P < 0.01). No significant differences were observed between the image quality scores for DLR and MBIR. The measured aortic annulus diameter had high interobserver and intraobserver agreement regardless of the reconstruction method (all intraclass correlation coefficients, >0.89).

CONCLUSIONS

In low tube voltage TAVI-CT, DLR provides higher image quality than HIR, and DLR provides higher image quality than MBIR in CCTA and is visually comparable to MBIR in aortoiliac CTA.

Transcatheter Aortic Valve Implantation: Addressing the Subsequent Risk of Permanent Pacemaker Implantation

Transcatheter aortic valve implantation (TAVI) is now a commonly used therapy in patients with severe aortic stenosis, even in those patients at low surgical risk. The indications for TAVI have broadened as the therapy has proven to be safe and effective. Most challenges associated with TAVI after its initial introduction have been impressively reduced; however, the possible need for post-TAVI permanent pacemaker implantation (PPI) secondary to conduction disturbances continues to be on the radar. Conduction abnormalities post-TAVI are always of concern given that the aortic valve lies in close proximity to critical components of the cardiac conduction system. This review will present a summary of noteworthy pre-and post-procedural conduction blocks, the best use of telemetry and ambulatory device monitoring to avoid unnecessary PPI or to recognize the need for late PPI due to delayed high-grade conduction blocks, predictors to identify those patients at greatest risk of requiring PPI, important CT measurements and considerations to optimize TAVI planning, and the utility of the MInimizing Depth According to the membranous Septum (MIDAS) technique and the cusp-overlap technique. It is stressed that careful membranous septal (MS) length measurement by MDCT during pre-TAVI planning is necessary to establish the optimal implantation depth before the procedure to reduce the risk of compression of the MS and consequent damage to the cardiac conduction system.

Preoperative TAVR Planning: How to Do It

Transcatheter aortic valve replacement (TAVR) is a well-established treatment option for patients with severe symptomatic aortic stenosis (AS) whose procedural efficacy and safety have been continuously improving. Appropriate preprocedural planning, including aortic valve annulus measurements, transcatheter heart valve choice, and possible procedural complication anticipation is mandatory to a successful procedure. The gold standard for preoperative planning is still to perform a multi-detector computed angiotomography (MDCT), which provides all the information required. Nonetheless, 3D echocardiography and magnet resonance imaging (MRI) are great alternatives for some patients. In this article, we provide an updated comprehensive review, focusing on preoperative TAVR planning and the standard steps required to do it properly.

Comparison of Deep Sedation and General Anesthesia With an Endotracheal Tube for Transcaval Transcatheter Aortic Valve Replacement: A Pioneering Institution's Experience

OBJECTIVES

Transcaval transcatheter aortic valve replacement (TC-TAVR) is an alternative approach to transcatheter aortic valve replacement involving deployment of the bioprosthetic valve via a conduit created from the inferior vena cava to the descending aorta in patients for whom the traditional transfemoral approach is not feasible. By analyzing the largest known cohort of TC-TAVR patients, the authors wished to compare hospital length of stay and post-procedure outcomes between patients who underwent the procedure under deep sedation (DS) and patients who underwent general anesthesia with an endotracheal tube.

DESIGN

Retrospective, single-center study.

SETTING

Henry Ford Hospital in Detroit, MI.

PARTICIPANTS

Patients undergoing TC-TAVR from 2015 to 2018.

MEASUREMENTS AND MAIN RESULTS

Seventy-nine patients were included in the analysis, which consisted of 38 under general anesthesia with an endotracheal tube and 41 under DS. The sample was divided into a general anesthesia (GA) group and DS group. There were no significant differences in implant success rate or post-procedure outcomes, including in-hospital mortality (p = 0.999) and major vascular complication rate (p = 0.481), between the two groups. Patients in the GA group stayed a median of 24 hours longer in the intensive care unit (ICU) (p < 0.001) and one day longer in the hospital (p = 0.046) after the procedure compared to patients in the DS group. The median procedure time was significantly lower (135 minutes) in the DS group compared to the GA group (167 minutes, p < 0.001).

CONCLUSIONS

Patients undergoing TC-TAVR under DS had similar postoperative outcomes and shorter post-procedure hospital and ICU lengths of stay compared to general anesthesia. In the authors' experience, DS is the preferred anesthetic technique for TC-TAVR.

Inter- and intra-observer repeatability of aortic annulus measurements on screening CT for transcatheter aortic valve replacement (TAVR): Implications for appropriate device sizing

OBJECTIVES

To investigate intra- and inter-observer repeatability of aortic annulus CT measurements for transcatheter aortic valve replacement (TAVR) by readers with different levels of experience and evaluate the impact of different multi-reader paradigms to improve prosthesis sizing.

METHODS

82 TAVR screening CTAs were evaluated twice by three raters with six (R1 = radiologist), three (R2 = 3D-laboratory technician) or zero (R3 = medical student) years of experience. Results were translated into hypothetical TAVR size recommendations. Intra- and inter-observer repeatability between single readers and three different multi-reader paradigms ([A]: two readers, [B]: three readers, or [C]: two readers + an optional third reader) were evaluated.

RESULTS

Intra-observer variability did not differ significantly (range: 50.1-67.8mm2). However, we found significant differences in mean inter-observer variance (p = 0.001). Multi-reader paradigms led to significantly increased precision (lower variability) for scenarios [B] and [C] (p = 0.03, p < 0.05). Compared to single readers, all multi-reader strategies clearly lowered the rate of discrepant device size categorization between repeated measurements (22-26% to 5-10%).

CONCLUSIONS

Aortic annulus CT measurements for TAVR are highly reproducible. Multi-reader strategies provide higher precision than evaluations from single readers with different levels of experience and could effectively be implemented with two readers and an optional third reader (Paradigm C) in a clinical setting.

Image quality and contrast agent exposure in cardiac computed tomography angiography prior to transcatheter aortic valve implantation procedures using different acquisition protocols

BACKGROUND

ECG-gated cardiac computed tomography angiography (CCTA) has found widespread use for prosthesis sizing before transcatheter aortic valve implantation (TAVI). However, still little data exists on the optimal scan-strategy in such patients. We hypothesized that prospectively triggered CCTA can enable the visualization of aortic valve structures and peripheral arteries with lower radiation and contrast agent exposure in patients considered for TAVI compared to retrospectively gated protocols.

METHODS

All studies were performed using a 256 multi-detector single source CT (iCT Philips, Best, Netherlands). With the prospective protocol the whole volume from the heart to the iliofemoral arteries scanned using prospective triggering. With the retrospective protocol a first retrospectively gated scan was performed for the heart and the iliofemoral part was subsequently scanned using a second non-triggered scan. Image quality was assessed semi-quantitatively and signal-to-noise- (SNR) and contrast-to-noise-ratios (CNR) were obtained for all scans.

RESULTS

Prospective CCTA was performed in 74 and in 34 patients, respectively using non-tailored and BMI adapted scans, whereas retrospective CCTA was performed in 57 patients. Prospective scans required lower contrast agent administration compared to retrospective scans (71 ± 8 mL versus 91 ± 15 mL, p < 0.01) and resulted in lower radiation exposure (26 ± 7mSv for retrospective versus 15 ± 3mSv for non-tailored prospective versus 8 ± 4mSv for BMI-adapted prospective scans, p < 0.01). Visual image quality was better for the evaluation of aortic valve structures and similar for the assessment of iliofemoral anatomy with prospective versus retrospective scans. In addition, contrast density, SNR and CNR were higher in the ascending aorta with prospective versus retrospective CCTA (434 ± 98HU versus 349 ± 112HU; 35 ± 14 versus 24 ± 9 and 31 ± 11 versus 16 ± 7, p < 0.001 for all). Subsection analysis by heart rate groups demonstrated that both image quality and CNR were significantly higher in patients with prospective versus retrospective CCTA, irrespective of the heart rate during image acquisition.

CONCLUSION

Prospectively triggered CCTA allows for improved visualization of aortic valve structures and peripheral arteries in patients scheduled for TAVI with simultaneously reduced contrast agent dose and radiation exposure. Therefore, this acquisition mode seems to be the preferred for the evaluation of patients considered for TAVI.

Ascending Aortic Endoballoon Occlusion Feasible despite Moderately Enlarged Aorta to Facilitate Robotic Mitral Valve Surgery

Objective

Aortic occlusion with an endoballoon is a well-established technique to facilitate robotic and minimally invasive mitral valve surgery. Use of the endoballoon has several relative contraindications including ascending aortic dilatation greater than 38 mm in size. We sought to review our experience using the endoballoon in cases of totally endoscopic mitral valve surgery with aortic diameters greater than 38 mm.

Methods

A retrospective review of our single-site database was conducted to identify patients undergoing totally endoscopic mitral valve surgery by a single surgeon using an endoballoon and who had ascending aortic dilation. We defined aortic dilation as greater than 38 mm. Computed tomography was done preoperatively on all patients to evaluate the aortic anatomy as well as iliofemoral access vessels. Femoral artery cannulation was done in a standardized fashion to advance and position the endoballoon, to occlude the ascending aorta, and to deliver cardioplegia.

Results

From October 2011 through June 2015,196 patients underwent totally endoscopic mitral valve surgery using an endoballoon at our institution. Twenty-two patients (11.2%) had ascending aortic diameters greater than 38 mm (range, 38.1–16.6 mm; mean, 40.5 ± 2.5 mm). In these cases, there were no instances of aortic dissection or other injury due to balloon rupture, balloon migration, device movement leading to loss of occlusion, or inability to complete planned surgery due to occlusion failure.

Conclusions

Our experience suggests that it is possible to successfully use endoaortic balloon occlusion in patients with ascending aortic dilation with proper preoperative imaging and planning.

Low contrast medium-volume third-generation dual-source computed tomography angiography for transcatheter aortic valve replacement planning

PURPOSE

To investigate feasibility, image quality and safety of low-tube-voltage, low-contrast-volume comprehensive cardiac and aortoiliac CT angiography (CTA) for planning transcatheter aortic valve replacement (TAVR).

MATERIALS AND METHODS

Forty consecutive TAVR candidates prospectively underwent combined CTA of the aortic root and vascular access route (270 mgI/ml iodixanol). Patients were assigned to group A (second-generation dual-source CT [DSCT], 100 kV, 60 ml contrast, 4.0 ml/s flow rate) or group B (third-generation DSCT, 70 kV, 40 ml contrast, 2.5 ml/s flow rate). Vascular attenuation, noise, signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were compared. Subjective image quality was assessed by two observers. Estimated glomerular filtration (eGFR) at CTA and follow-up were measured.

RESULTS

Besides a higher body-mass-index in group B (24.8±3.8 kg/m² vs. 28.1±5.4 kg/m², P=0.0339), patient characteristics between groups were similar (P≥0.0922). Aortoiliac SNR (P=0.0003) was higher in group B. Cardiac SNR (P=0.0003) and CNR (P=0.0181) were higher in group A. Subjective image quality was similar (P≥0.213) except for aortoiliac image noise (4.42 vs. 4.12, P=0.0374). TAVR-planning measurements were successfully obtained in all patients. There were no significant changes in eGFR among and between groups during follow-up (P≥0.302).

CONCLUSION

TAVR candidates can be safely and effectively evaluated by a comprehensive CTA protocol with low contrast volume using low-tube-voltage acquisition.

KEY POINTS

• Third-generation dual-source CT facilitates low-tube-voltage acquisition. • TAVR planning can be performed with reduced contrast volume and radiation dose. • TAVR-planning CT did not result in changes in creatinine levels at follow-up. • TAVR candidates can be safely evaluated by comprehensive low-tube-voltage CT angiography.

Multimodality Assessment of Ascending Aortic Diameters: Comparison of Different Measurement Methods

BACKGROUND

Transthoracic echocardiography (TTE), multidetector computed tomography (MDCT), and magnetic resonance imaging (MRI) have been widely used to monitor aortic diameters, with no consensus as to the best measurement approach. Thus, the aim of this study was to establish the best measurement methods by two-dimensional (2D) TTE, MDCT, and MRI to achieve comparable aortic diameters.

METHODS

One hundred forty patients with severe aortic valvular disease or aortic dilatation were prospectively evaluated using 2D TTE and MDCT (n = 70) or MRI (n = 70). The aorta was measured at three different levels: sinuses of Valsalva, sinotubular junction, and ascending aorta. Three different measurements were made by 2D TTE-inner edge to inner edge, leading edge to leading edge (L-L), and outer edge to outer edge-and then compared with the inner edge-to-inner edge and outer edge-to-outer edge measurements of cusp-to-cusp and cusp-to-commissure diameters by MDCT or MRI. Inter- and intraobserver variability was analyzed.

RESULTS

Aortic diameters by 2D TTE, MDCT, and MRI showed excellent inter- and intraobserver variability using all conventions. Significant underestimation was observed of all aortic diameters assessed by 2D TTE using the inner edge-to-inner edge convention compared with those obtained by MDCT or MRI (P < .0001). However, excellent accuracy was observed by 2D TTE when the L-L convention was used and compared with the internal diameter by MDCT and MRI (mean differences, 0.6 ± 2.6 mm [P = .158] for MDCT and 0.4 ± 3.5 mm [P = .852] for MRI). Cusp-to-cusp diameters were slightly larger than cusp-to-commissure diameters. The diameter by 2D TTE using the L-L convention correlated best with the noncoronary cusp-to-right coronary cusp diameter determined by both MDCT and MRI.

CONCLUSIONS

Aortic root and ascending aortic diameters measured by 2D TTE using the L-L convention showed accurate and reproducible values compared with internal diameters assessed by MDCT or MRI. This approach permits a multimodality follow-up of patients with aortic diseases and avoids disparities in measurements obtained by different conventions.

Aortic root volume is associated with contained rupture of the aortic annulus in balloon-expandable transcatheter aortic valve replacement

BACKGROUND

Aortic annulus rupture is a rare, but potentially fatal complication of transcatheter aortic valve replacement (TAVR), especially when it occurs by balloon-expandable devices. In order to improve the predictability of procedures and avoid ruptures we investigated whether or not the aortic root volume measures is a useful indicator of risk, and if it could be useful for the prosthesis size selection.

METHODS AND RESULTS

From a retrospective series of 172 TAVR patients, seven experienced contained aortic annulus ruptures. The receiver operating curves were used to illustrate sensitivity and specificity of the different aortic annulus size and aortic root volume measures. The annulus area oversizing of ≥20% resulted in a sensitivity of 100%, specificity of 55.76%, and positive predictive value (PPV) of 8.75%. In patients receiving 26 mm prostheses, the aortic root volume (ARV <13600 mm(3)) provided a better specificity and PPV (79.63 and 18.52%, respectively). A two-step testing procedure considering the area derived average annulus diameter (Darea <23 mm) as a first separating parameter and then the ARV (<13,600 mm(3)) as a further indicator showed the most promising results with the PPV of 31.25%. Regardless of the procedure steps no false negative results were predicted.

CONCLUSIONS

Our data show that the ARV provides a better predictive value for correct prosthesis sizing than established annulus measurements, especially in 'borderline' annuli. We suggest a two-step testing procedure for prostheses size selection, considering Darea and ARV to minimize the risk of annulus rupture. Prospective studies and examination of larger datasets are warranted to confirm these findings.

Low-volume contrast medium protocol for comprehensive cardiac and aortoiliac CT assessment in the context of transcatheter aortic valve replacement

RATIONALE AND OBJECTIVES

To investigate the diagnostic performance of a comprehensive computed tomography (CT) protocol for both cardiac and aortoiliac evaluation of patients considered for transcatheter aortic valve replacement (TAVR) using a single, low-volume contrast medium (CM) injection.

MATERIALS AND METHODS

Forty-four TAVR candidates were retrospectively analyzed. All underwent retrospectively electrocardiogram-gated cardiac CT followed by high-pitch CT angiography of the aortoiliac vasculature using one of two single injection protocols of 320 mgI/mL iodine CM: group A (n = 22), iodine delivery rate-based (1.28 gI/s), 60-mL CM volume, 4.0 mL/s flow rate; group B (n = 22), clinical routine protocol, 100-mL CM volume, 4.0 mL/s flow rate. Mean arterial attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were calculated. Subjective image quality was assessed.

RESULTS

Aortic root and iliofemoral dimensions could be analyzed in all cases. Patient characteristics showed no significant differences. Mean attenuation at the levels of the aortic root (285.8 ± 83.0 HU vs 327.5 ± 70.8 HU, P = .080) and the iliofemoral access route (256.8 ± 88.5 HU vs 307.5 ± 93.2 HU, P = .071), as well as SNR and CNR were nonsignificantly lower in group A compared to group B. Subjective image quality was equivalent.

CONCLUSIONS

In multimorbid TAVR patients, the performance of a combined CT protocol using a single low-volume CM bolus is feasible with maintained image quality compared to a standard protocol.

Feasibility of ultra-low contrast 64-slice computed tomography angiography before transcatheter aortic valve implantation: a real-world experience

AIMS

To investigate the feasibility, image quality, and clinical implications of an ultra-low-dose contrast injection computed tomography angiography (CTA) protocol in patients scheduled for transcatheter aortic valve implantation (TAVI).

METHODS AND RESULTS

Images obtained with 64-slice CT were retrospectively evaluated in 162 TAVI candidates with a body mass index (BMI) of ≤29 kg/m(2). A multiphasic, low iodine dose and BMI-adapted CM protocol was administered in all patients (BMI <22 kg/m(2): 40 mL; BMI 22-29 kg/m(2): 55 mL). All images were evaluated for image quality, vessel attenuation, and estimated radiation dose. The anatomy, diameters, perimeter, and area of the aortic annulus were assessed. Anatomy and diameters of peripheral vessels were also evaluated. Image quality of the aortic root and ilio-femoral vessels was diagnostic in all patients. Vascular attenuation was >200 HU at any vessel level. The mean diameters of the aortic annulus were 22 ± 3 mm (range: 16-28 mm) × 26 ± 3 mm (range: 20-33 mm); the mean perimeter was 77.0 ± 7.1 mm. After CTA, a total of 137 patients (84.6%) underwent TAVI. Mean estimated radiation dose was 20.2 ± 4.6 mSv.

CONCLUSION

With our protocol, we achieved images of the aortic annulus and aorto-iliac anatomy of sufficient quality to allow patient selection and procedural planning for TAVI, with a substantial reduction of the amount of injected CM.

Pre-interventional assessment and calcification score of the aortic valve and annulus, with multi-detector CT, in transcatheter aortic valve implantation (TAVI) using the Medtronic CoreValve

Background: Transcatheter aortic valve implantation (TAVI) provides an acceptable alternative for aortic valve replacement in the elderly, but needs accurate pre-procedural imaging to optimise intervention. Objectives: To evaluate an alternative manual aortic valve calcification scoring system with computed tomography, for patients undergoing TAVI. We hypothesise a correlation between the Free State aortic valve calcium computed tomography score (FACTS) scoring system, valve plaque density and procedure-related complications. Methods: Twenty patients suitable for TAVI were selected according to standard international guidelines and received multimodality imaging prior to intervention. Images were reviewed by two reviewers who were blinded to each other’s scores. Where large inter-individual score variations existed, retraining was done and scores repeated, using a double-blinded method. Matched scores were included in the final analysis. Rosenhek calcification scores were used as a standard of reference. Results: The study comprised 9 (45%) men and 11 (55%) women, with a median age of 83.5 years. Median EuroSCORE was 15.5. FACTS scores ≥6 were associated with the presence of a paravalvular leak (p = 0.01). Procedure-related complications (left bundle branch block, repositioning of the valve and anaemia) were seen in patients with plaques measuring ≥1000 HU (p = 0.07). Conclusion: The FACTS score and averaged valve plaque HU showed potential for predicting a paravalvular leak and procedure-related complications, and could be valuable in the future for optimising patient selection for TAVI.

A novel contribution towards coherent and reproducible intravalvular measurement of the aortic annulus by multidetector computed tomography ahead of transcatheter aortic valve implantation

BACKGROUND

As current multidetector computed tomography (MDCT) measurements underestimate the size of the aortic annulus ahead of transcatheter aortic valve implantation (TAVI), a strategy of approximate annulus area oversizing has been adopted recently.

AIMS

To measure the aortic annulus using a novel complementary intravalvular MDCT slice.

METHODS

Fifty-five patients with severe aortic stenosis were selected for MDCT ahead of and 1 month after CoreValve(®) TAVI. Two MDCT slices were analysed and compared: the current standard virtual basal ring (VBR) at the nadir of the aortic cusps; and a novel slice, defined as the basal (lowest) complete commissural coaptation (BCCC) plane.

RESULTS

BCCC is an intravalvular plane lying 5.2±0.8 mm above the VBR. The BCCC annulus is almost circular, unlike the VBR (mean eccentricity index 0.09±0.04 vs 0.3±0.1, respectively). The mean BCCC annulus diameter was 26.6±2.3 mm, 16% larger than that of the VBR (23.9±2.2 mm; P<0.001). The BCCC annulus area proved coherent with the orifice area measured after TAVI on the projection of the same slice (i.e. systematically equal to or greater than the latter [mean difference, +2.3±1.4 mm]), in contrast to the wider scatter found for the VBR (-1.3±2.0 mm). Once the sclerotic calcified valves have been pushed back by the implant, the aortic orifice after TAVI will inevitably be equal to or less than the diameter of the virtually unvalved annulus before TAVI.

CONCLUSION

Based on the present results, we recommend including a BCCC slice to complete aortic annulus sizing, in order to optimize implant calibration.

MDCT evaluation of aortic root and aortic valve prior to TAVI. What is the optimal imaging time point in the cardiac cycle?

OBJECTIVES

To determine the optimal imaging time point for transcatheter aortic valve implantation (TAVI) therapy planning by comprehensive evaluation of the aortic root.

METHODS

Multidetector-row CT (MDCT) examination with retrospective ECG gating was retrospectively performed in 64 consecutive patients referred for pre-TAVI assessment. Eighteen different parameters of the aortic root were evaluated at 11 different time points in the cardiac cycle. Time points at which maximal (or minimal) sizes were determined, and dimension differences to other time points were evaluated. Theoretical prosthesis sizing based on different measurements was compared.

RESULTS

Largest dimensions were found between 10 and 20% of the cardiac cycle for annular short diameter (10%); mean diameter (10%); effective diameter and circumference-derived diameter (20%); distance from the annulus to right coronary artery ostium (10%); aortic root at the left coronary artery level (20%); aortic root at the widest portion of coronary sinuses (20%); and right leaflet length (20%). Prosthesis size selection differed depending on the chosen measurements in 25-75% of cases.

CONCLUSION

Significant changes in anatomical structures of the aortic root during the cardiac cycle are crucial for TAVI planning. Imaging in systole is mandatory to obtain maximal dimensions.

KEY POINTS

• Most aortic root structures undergo significant dimensional changes throughout the cardiac cycle. • The largest dimensions of aortic parameters should be determined to optimize TAVI. • Circumference-derived diameter showed maximum dimension at 20% of the cardiac cycle.

The Role of Computed Tomography Angiography in Patients Undergoing Evaluation for Minimally Invasive Cardiac Surgery: An Early Program Experience

Objective

An increasing number of patients are undergoing surgical procedures using minimally invasive cardiac surgery (MICS). These techniques use conventional or retrograde arterial perfusion with direct aortic cross-clamping or endoballoon occlusion. Precise knowledge of the arterial tree is required to avoid complications and to plan for the operation. We examined the role of computed tomography angiography (CTA) in evaluating patients for MICS.

Methods

We reviewed all consecutive candidates undergoing CTA during preoperative evaluation for MICS aortic, mitral, tricuspid, Maze, atrial septal defect, or myxoma procedures between February 2008 and May 2010. The CTA findings of patients excluded from MICS were compared against those successfully undergoing MICS.

Results

One hundred eleven MICS candidates underwent preoperative CTA. Thirty-five (32%) had single or multiple CTA findings precluding MICS and underwent sternotomy. Seventy-six (68%) had favorable CTA findings and underwent MICS. The MICS group had a mean age of 62 years, with 29 women (39%); the non-MICS group had a mean age of 68 years, with 17 women (48%). Of the patients excluded from MICS, two (6%) had diminished or absent lower extremity pulses. All MICS patients (except for aortic) had successful use of the endoballoon. There were no perfusion or peripheral vascular complications. There was one stroke, one lymphocele, and one death (chronic obstructive pulmonary disease exacerbation).

Conclusions

Computed tomography angiography is of fundamental importance in evaluating patients for MICS. It can identify calcified regions that make for threatening catheter passage with subsequent retrograde arterial perfusion. Abnormalities of the arterial tree are identified. The use of CTA-guided patient selection can thus avoid major perioperative complications.

Caval-aortic access to allow transcatheter aortic valve replacement in otherwise ineligible patients: initial human experience

OBJECTIVES

This study describes the first use of caval-aortic access and closure to enable transcatheter aortic valve replacement (TAVR) in patients who lacked other access options. Caval-aortic access refers to percutaneous entry into the abdominal aorta from the femoral vein through the adjoining inferior vena cava.

BACKGROUND

TAVR is attractive in high-risk or inoperable patients with severe aortic stenosis. Available transcatheter valves require large introducer sheaths, which are a risk for major vascular complications or preclude TAVR altogether. Caval-aortic access has been successful in animals.

METHODS

We performed a single-center retrospective review of procedural and 30-day outcomes of prohibitive-risk patients who underwent TAVR via caval-aortic access.

RESULTS

Between July 2013 and January 2014, 19 patients underwent TAVR via caval-aortic access; 79% were women. Caval-aortic access and tract closure were successful in all 19 patients; TAVR was successful in 17 patients. Six patients experienced modified VARC-2 major vascular complications, 2 (11%) of whom required intervention. Most (79%) required blood transfusion. There were no deaths attributable to caval-aortic access. Throughout the 111 (range 39 to 229) days of follow up, there were no post-discharge complications related to tract creation or closure. All patients had persistent aorto-caval flow immediately post-procedure. Of the 16 patients who underwent repeat imaging after the first week, 15 (94%) had complete closure of the residual aorto-caval tract.

CONCLUSIONS

Percutaneous transcaval venous access to the aorta allows TAVR in otherwise ineligible patients, and may offer a new access strategy for other applications requiring large transcatheter implants.

Incidental findings in computed tomographic angiography for planning percutaneous aortic valve replacement: advanced age, increased cancer prevalence?

BACKGROUND

Increased age is linked with a higher cancer risk according to model calculations. Patients with severe atherosclerotic aortic stenosis are of old age, therefore, a high incidence of malignancies should be found.

PURPOSE

To evaluate the prevalence of clinically significant and potentially malignant incidental findings at computed tomographic angiography (CTA) performed in patients with severe aortic stenosis being assessed as to their suitability for transcatheter aortic valve replacement (TAVR).

MATERIAL AND METHODS

Between August 2008 and April 2010, CTA of the thoraco-abdominal aorta and the pelvic arterial vessels was performed in 131 patients. There were 62 women (47%) and 69 men (53%); the mean age was 81.6 years (range, 64-91 years). Incidental findings were recorded and categorized as potentially malignant, clinically significant, and clinically insignificant. Clinically significant findings were defined as those requiring immediate therapy, intervention or imaging, or follow-up examination.

RESULTS

Of the 131 study patients, 31 (23.7%) presented significant extravascular incidental findings, 19 (14.5%) in the thorax, and 12 (9.2%) in the abdomen. Five lesions (3.8%) were considered potentially malignant, three of them (2.3%) were new and highly suspicious for malignancies (two renal cell carcinomas and one hepatocellular carcinoma). In two patients (1.5%) mediastinal lymphadenopathy was found (recurrent malignant lymphoma und new metastases from known bladder cancer).

CONCLUSION

The prevalence of highly suspicious malignant incidental findings in patients undergoing TAVR is 3.8% with an average age of 81.6 years which is not high compared to prevalence in the literature dealing with patients aged <70 years.

ACR appropriateness criteria imaging for transcatheter aortic valve replacement

Although aortic valve replacement is the definitive therapy for severe aortic stenosis, almost half of patients with severe aortic stenosis are unable to undergo conventional aortic valve replacement because of advanced age, comorbidities, or prohibitive surgical risk. Treatment options have been recently expanded with the introduction of catheter-based implantation of a bioprosthetic aortic valve, referred to as transcatheter aortic valve replacement. Because this procedure is characterized by lack of exposure of the operative field, image guidance plays a critical role in preprocedural planning. This guideline document evaluates several preintervention imaging examinations that focus on both imaging at the aortic valve plane and planning in the supravalvular aorta and iliofemoral system. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Conformational pulsatile changes of the aortic annulus: impact on prosthesis sizing by computed tomography for transcatheter aortic valve replacement

OBJECTIVES

This study sought to investigate pulsatile changes of the aortic annulus and their impact on prosthesis selection by computed tomography (CT).

BACKGROUND

Precise noninvasive prosthesis sizing is a prerequisite for transcatheter aortic valve replacement.

METHODS

A total of 110 patients with severe aortic stenosis (mean age: 82.9 ± 8 years, mean aortic valve area: 0.69 ± 0.18 cm(2)) underwent electrocardiogram-gated CT. Aortic annulus dimensions were planimetrically quantified as area-derived diameter (D(A) = 2 ×✓(CSA/π), where CSA is the cross-sectional area) and perimeter-derived diameter (D(P) = P/π, where P is the length of the perimeter) in 5% increments of the RR interval. Hypothetical prosthesis sizing was based on D(A) and D(P) (23-mm prosthesis for <22 mm; 26 mm: 22 to 25 mm; 29 mm: >25 mm) and compared between maximum and traditional cardiac CT reconstruction phases at 35% and 75% of RR. Agreement for prosthesis selection was calculated by κ statistics.

RESULTS

D(A) and D(P) were increased and eccentricity was reduced during systole, with D(A-MAX) and D(P-MAX) most often observed at 20% of RR. D(P) was consistently larger than D(A). Average net differences were 2.0 ± 0.6 mm and 1.7 ± 0.5 mm by D(A-MIN) versus D(A-MAX) and D(P-MIN) versus D(P-MAX). Agreement for prosthesis sizing was found in 93 of 110 patients (κ = 0.75) by D(A-75%) and in 80 of 110 patients (κ = 0.53) by D(A-MAX) compared with D(A-35%); and in 94 of 110 patients (κ = 0.73) by D(P-75%) and in 93 of 110 patients (κ = 0.73) by D(P-MAX) compared with D(P-35%). With sizing by D(A-75%) or D(P-75%), nominal prosthesis diameter was smaller than D(A-MAX) or D(P-MAX) in 15 and 6 patients respectively.

CONCLUSIONS

Aortic annulus morphology exhibits conformational pulsatile changes throughout the cardiac cycle due to deformation and stretch. These changes affect prosthesis selection. Prosthesis selection by diastolic perimeter- or area-derived dimensions harbors the risk of undersizing.

Prosthesis oversizing in balloon-expandable transcatheter aortic valve implantation is associated with contained rupture of the aortic root

BACKGROUND

To retrospectively investigate the potential cause of contained rupture of the aortic root in balloon-expandable transcatheter aortic valve implantation (TAVI) by means of pre- and postinterventional multislice computed tomography.

METHODS AND RESULTS

Seventy-two patients (mean age 82±7 years, mean aortic valve area 0.69±0.19 cm(2)) underwent balloon-expandable TAVI using the EdwardsSAPIEN Transcatheter Heart Valve (23 mm, n=19; 26 mm, n=50; 29 mm, n=3). Aortic annulus dimensions were quantified by multislice computed tomography-based cross-sectional area assessment and average diameter calculation (CAAD) before and after TAVI. Post-TAVI multislice computed tomography data sets were available in 65 patients; contained aortic root rupture was diagnosed in 3 patients. Pre-TAVI CAAD was 23.1±1.8 mm; post-TAVI CAAD was 22.9±1.3 mm. Median relative change in CAAD pre- and post-TAVI was -0.5% (interquartile range, 3.6%). Relative increase of 5% to 10% was observed in 4 patients (1 with contained rupture), relative increase >10% in 2 patients, both with contained rupture. Mean relative oversizing, calculated as the relative difference in diameter between pre-TAVI CAAD and nominal diameter of the selected prosthesis, was 9.8%±7.8%. Relative oversizing was significantly higher in patients with contained rupture compared with patients without contained rupture (24.6%±5.4% versus 9.1%±6.6%; P<0.001). Relative oversizing ≥20% occurred in 6 patients (3 with contained rupture).

CONCLUSIONS

Contained rupture of the aortic root in balloon-expandable TAVI is associated with severe prosthesis oversizing. Multislice computed tomography-based assessment of aortic annulus dimension in conjunction with adapted sizing guidelines may reduce the incidence of severe oversizing.

Clinical indications for cardiac computed tomography. From the Working Group of the Cardiac Radiology Section of the Italian Society of Medical Radiology (SIRM)

Cardiac computed tomography (CCT) has grown as a useful means in different clinical contexts. Technological development has progressively extended the indications for CCT while reducing the required radiation dose. Even today there is little documentation from the main international scientific societies describing the proper use and clinical indications of CCT; in particular, there are no complete guidelines. This document reflects the position of the Working Group of the Cardiac Radiology Section of the Italian Society of Radiology concerning the indications for CCT.