Quantitative aortography for assessment of aortic regurgitation in the era of percutaneous aortic valve replacement

Paravalvular leak (PVL) is a shortcoming that can erode the clinical benefits of transcatheter valve replacement (TAVR) and therefore a readily applicable method (aortography) to quantitate PVL objectively and accurately in the interventional suite is appealing to all operators. The ratio between the areas of the time-density curves in the aorta and left ventricular outflow tract (LVOT-AR) defines the regurgitation fraction (RF). This technique has been validated in a mock circulation; a single injection in diastole was further tested in porcine and ovine models. In the clinical setting, LVOT-AR was compared with trans-thoracic and trans-oesophageal echocardiography and cardiac magnetic resonance imaging. LVOT-AR > 17% discriminates mild from moderate aortic regurgitation on echocardiography and confers a poor prognosis in multiple registries, and justifies balloon post-dilatation. The LVOT-AR differentiates the individual performances of many old and novel devices and is being used in ongoing randomized trials and registries.

Online Quantitative Aortographic Assessment of Aortic Regurgitation After TAVR: Results of the OVAL Study

OBJECTIVES

The aim of this study was to investigate the online assessment feasibility of aortography using videodensitometry in the catheterization laboratory during transcatheter aortic valve replacement (TAVR).

BACKGROUND

Quantitative assessment of regurgitation after TAVR through aortography using videodensitometry is simple, reproducible, and validated in vitro, in vivo, in clinical trials, and in "real-world" patients. However, thus far the assessment has been done offline.

METHODS

This was a single center, prospective, proof-of-principle, feasibility study. One hundred consecutive patients with aortic stenosis and indications to undergo TAVR were enrolled. All final aortograms were analyzed immediately after acquisition in the catheterization laboratory and were also sent to an independent core laboratory for blinded offline assessment. The primary endpoint of the study was the feasibility of the online assessment of regurgitation (percentage of analyzable cases). The secondary endpoint was the reproducibility of results between the online assessment and the offline analysis by the core laboratory.

RESULTS

Patients' mean age was 81 ± 7 years, and 56% were men. The implanted valves were either SAPIEN 3 (97%) or SAPIEN 3 Ultra (3%). The primary endpoint of online feasibility of analysis was 92% (95% confidence interval [CI]: 86% to 97%) which was the same feasibility encountered by the core laboratory (92%; 95% CI: 86% to 97%). Reproducibility assessment showed a high correlation between online and core laboratory evaluations (R² = 0.87, p < 0.001), with an intraclass correlation coefficient of 0.962 (95% CI: 0.942 to 0.975; p < 0.001).

CONCLUSIONS

This study showed high feasibility of online quantitative assessment of regurgitation and high agreement between the online examiner and core laboratory. These results may pave the way for the application of videodensitometry in the catheterization laboratory after TAVR. (Online Videodensitometric Assessment of Aortic Regurgitation in the Cath-Lab [OVAL]; NCT04047082).

Hinge point-based annular plane with abnormal aortic cusps in transcatheter aortic valve replacement

A virtual aortic annular plane that is built using the three hinge points, known as the hinge point-based annular plane (HPAP), is routinely used during transcatheter aortic valve replacement (TAVR). Abnormal aortic cusps (AAC) with unequal length and size influence the relationship of the HPAP to the aortic root axis significantly and pose challenges to valve deployment, leading to paravalvular leak and valve embolisation. Obtaining a centreline-based aortic annular plane in addition may help to understand valve deployment behaviour in AAC better.

Transcatheter heart valve interventions: where are we? Where are we going?

Transcatheter heart valve interventions have transformed the outcomes of patients with valvular heart disease (VHD) who are unfavourable candidates for surgery. Technological advances have allowed extension of these interventions to younger or lower risk patients and those with other forms of VHD and may in the future permit earlier treatment of VHD in less symptomatic patients or those with moderate disease. The balance of risks and benefits is likely to differ between lower and higher risk patients, and more evidence is needed to evaluate the net benefit of transcatheter technology in these groups. As academic researchers, clinicians, industry, and patient stakeholders collaborate to research these broader indications for transcatheter valve interventions, it is essential to address (i) device durability and deliverability, (ii) specific anatomical needs (e.g. bicuspid aortic valves, aortic regurgitation, mitral and tricuspid valve disease), (iii) operator training, and (iv) the reinforced importance of the multidisciplinary Heart Team.

"Vascular Outlining": Augmented Imaging for Transfemoral Access-A Preclinical Investigation

BACKGROUND

Advanced visualization software tools have been used in clinics to improve the safety and accuracy of transcatheter procedure. Imaging techniques have greatly evolved during the era of transcatheter aortic valve implantation (TAVI). In a retrospective analysis, we investigated the feasibility of augmented fluoroscopy for iliofemoral access using a novel "Vascular Outlining" roadmapping technology.

METHODS

The Vascular Outlining prototype device (Philips Healthcare) application was used with iliofemoral angiography of 10 patients undergoing transfemoral TAVI. The software processes any conventional angiographic sequences, extracting the static outline of vessels and projecting the two-dimensional vessel margins as a roadmap on live fluoroscopy. Post-processed results were clinically assessed to determine whether the technical performance of the tool is sufficient.

RESULTS

Augmented imaging was possible in all investigated angiography sequences. The analysis of software-generated images showed accurate projection of the two-dimensional outline of the iliofemoral vessels as an overlay on the live fluoroscopy image in most cases. Overlay inaccuracy was only observed in cases with low contrast or patient movement.

CONCLUSION

In static and contrasted angiography sequences, "Vascular Outlining" showed accurate image overlay. We identified that the quality of the vascular outline is dependent on the opacification of the contrast injection and the stability of the patient on the table. With further development. this application might increase the accuracy of femoral puncture and reduce the incidence of vascular complications. Clinical trials are needed to confirm these hypotheses.

Feasibility and applicability of static vascular outline roadmapping during transcatheter aortic valve implantation

BACKGROUND

We investigated the application and feasibility of a novel software tool designed for the visualization of the aortic root during transcatheter aortic valve implantation (TAVI). The final positioning of the device prior deployment remains the most critical phase during TAVI.

METHODS

Philips "Vascular Outlining" prototype application was used during balloon expandable Edwards Lifesciences SapienXT valve deployment. It processes any angiographic sequences, extracting the static outline of vessels and projecting the two-dimensional vessel margins as a roadmap on live fluoroscopy. Preoperational planning, sizing and anatomical assessment of access routes were performed using computed tomography scans and the Philips "HeartNavigator" software.

RESULTS

Fifteen high-risk aortic stenosis patients (mean age 82.0±6.6 years) underwent TAVI via transfemoral (N.=8), transapical (N.=4), and transaortic (N.=3) access routes. Mean logistic EuroSCOREs and STS-scores were 19.7±4.3% and 7.9±3.1%, respectively, mean aortic gradient was 66.3±18.3 mmHg. All valves were implanted successfully with none or trivial paravalvular regurgitation in 11 patients, mild in 3 patients, and moderate in 1 patient. TAVI was performed in all cases with only one aortic root contrast media injection during valve deployment. No major stroke or cardiovascular death occurred within 30 days.

CONCLUSIONS

"Vascular Outlining"-guided implantation of the SapienXT valve is feasible. This new feature might increase the accuracy of valve placement and also may reduce the need for extra contrast media use during valve deployment. However, the lack of real-time motion compensation limits its wide application, as the overlay does not move together with respiratory and cardiac motion.

Substantial radiation reduction in pediatric and adult congenital heart disease interventions with a novel X-ray imaging technology

Background

Pediatric catheterization exposes patients to varying radiation doses. Concerns over the effects of X-ray radiation dose on the patient population have increased in recent years. This study aims at quantifying the patient radiation dose reduction after the introduction of an X-ray imaging technology using advanced real time image noise reduction algorithms and optimized acquisition chain for fluoroscopy and exposure in a pediatric and adult population with congenital heart disease.

Methods

Patient and radiation dose data was retrospectively collected (July 2012–February 2013) for 338 consecutive patients treated with a system using state of the art image processing and reference acquisition chain (referred as “reference system”). The same data was collected (March–October 2013) for 329 consecutive patients treated with the new imaging technology (Philips AlluraClarity, referred as “new system”). Patients were divided into three weight groups: A) below 10 kg, B) 10–40 kg, and C) over 40 kg. Radiation dose was quantified using dose area product (DAP), while procedure complexity using fluoroscopy time, procedure duration and volume of contrast medium.

Results

The new system provides significant patient dose reduction compared to the reference system. Median DAP values were reduced in group A) from 140.6 cGy·cm² to 60.7 cGy·cm², in group B) from 700.0 cGy·cm² to 202.2 cGy·cm² and in group C) from 4490.4 cGy·cm² to 1979.8 cGy·cm² with reduction of 57%, 71% and 56% respectively (p < 0.0001 for all groups).

Conclusions

Despite no other changes in procedural approach, the novel X-ray imaging technology provided substantial radiation dose reduction of 56% or higher.

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x-ray radiation dose in pediatric patients is of specific concern as congenital heart disease is more often treated by interventional measures.

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the effect of advanced real time image noise reduction algorithms and optimized acquisition chain for fluoroscopy and exposure was studied.

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A state of the art image processing and reference acquisition chain was compared to the new imaging technology in 338 vs 329 consecutive patients.

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Patients were divided into three weight groups: A) below 10 kg, B) 10-40 kg, and C) over 40 kg according to clinical practice and procedure complexity.

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the novel X-ray imaging technology provided substantial radiation dose reduction of 56% or higher.

CT angiography-fluoroscopy fusion imaging for percutaneous transapical access

OBJECTIVES

The aim of this proof-of-principle study is to validate the accuracy of fusion imaging for percutaneous transapical access (TA).

BACKGROUND

Structural heart disease interventions, including TA, are commonly obtained under fluoroscopic guidance, which lacks important spatial information. Computed tomographic angiography (CTA)-fluoroscopy fusion imaging can provide the 3-dimensional information necessary for improved accuracy in planning and guidance of these interventions.

METHODS

Twenty consecutive patients scheduled for percutaneous left ventricular puncture and device closure using CTA-fluoroscopy fusion guidance were prospectively recruited. The HeartNavigator software (Philips Healthcare, Best, the Netherlands) was used to landmark the left ventricular epicardium for TA (planned puncture site [PPS]). The PPS landmark was compared with the position of the TA closure device on post-procedure CTA (actual puncture site). The distance between the PPS and actual puncture site was calculated from 2 fixed reference points (left main ostium and mitral prosthesis center) in 3 planes (x, y, and z). The distance from the left anterior descending artery at the same z-plane was also assessed. TA-related complications associated with fusion imaging were recorded.

RESULTS

The median (interquartile range [IQR]) TA distance difference between the PPS and actual puncture site from the referenced left main ostium and mitral prosthesis center was 5.00 mm (IQR: 1.98 to 12.64 mm) and 3.27 mm (IQR: 1.88 to 11.24 mm) in the x-plane, 4.48 mm (IQR: 1.98 to 13.08 mm) and 4.00 mm (IQR: 1.62 to 11.86 mm) in the y-plane, and 5.57 mm (IQR: 3.89 to 13.62 mm) and 4.96 mm (IQR: 1.92 to 11.76 mm) in the z-plane. The mean TA distance to the left anterior descending artery was 15.5 ± 7.8 mm and 22.7 ± 13.7 mm in the x- and y-planes. No TA-related complications were identified, including evidence of coronary artery laceration.

CONCLUSIONS

With the use of CTA-fluoroscopy fusion imaging to guide TA, the actual puncture site can be approximated near the PPS. Moreover, fusion imaging can help maintain an adequate access distance from the left anterior descending artery, thereby, potentially reducing TA-related complications.

Onset timing of cross-sensory activations and multisensory interactions in auditory and visual sensory cortices

Here we report early cross-sensory activations and audiovisual interactions at the visual and auditory cortices using magnetoencephalography (MEG) to obtain accurate timing information. Data from an identical fMRI experiment were employed to support MEG source localization results. Simple auditory and visual stimuli (300-ms noise bursts and checkerboards) were presented to seven healthy humans. MEG source analysis suggested generators in the auditory and visual sensory cortices for both within-modality and cross-sensory activations. fMRI cross-sensory activations were strong in the visual but almost absent in the auditory cortex; this discrepancy with MEG possibly reflects the influence of acoustical scanner noise in fMRI. In the primary auditory cortices (Heschl's gyrus) the onset of activity to auditory stimuli was observed at 23 ms in both hemispheres, and to visual stimuli at 82 ms in the left and at 75 ms in the right hemisphere. In the primary visual cortex (Calcarine fissure) the activations to visual stimuli started at 43 ms and to auditory stimuli at 53 ms. Cross-sensory activations thus started later than sensory-specific activations, by 55 ms in the auditory cortex and by 10 ms in the visual cortex, suggesting that the origins of the cross-sensory activations may be in the primary sensory cortices of the opposite modality, with conduction delays (from one sensory cortex to another) of 30-35 ms. Audiovisual interactions started at 85 ms in the left auditory, 80 ms in the right auditory and 74 ms in the visual cortex, i.e., 3-21 ms after inputs from the two modalities converged.

Identifying brain regions for integrative sensorimotor processing with ankle movements

The objective of this study was to define cortical and subcortical structures activated during both active and passive movements of the ankle, which have a fundamental role in the physiology of locomotion, to improve our understanding of brain sensorimotor integration. Sixteen healthy subjects, all right-foot dominant, performed a dorsi-plantar flexion task of the foot using a custom-made wooden manipulandum, which enabled measurements of the movement amplitude. All subjects underwent a training session, which included surface electromyography, and were able to relax completely during passive movements. Patterns of activation during active and passive movements and differences between functional MRI (fMRI) responses for the two types of movement were assessed. Regions of common activation during the active and passive movements were identified by conjunction analysis. We found that passive movements activated cortical regions that were usually similar in location to those activated by active movements, although the extent of the activations was more limited with passive movements. Active movements of both feet generated greater activation than passive movements in some regions (such as the ipsilateral primary motor cortex) identified in previous studies as being important for motor planning. Common activations during active and passive movements were found not only in the contralateral primary motor and sensory cortices, but also in the premotor cortical regions (such as the bilateral rolandic operculum and contralateral supplementary motor area), and in the subcortical regions (such as the ipsilateral cerebellum and contralateral putamen), suggesting that these regions participate in sensorimotor integration for ankle movements. In future, similar fMRI studies using passive movements have potential to elucidate abnormalities of sensorimotor integration in central nervous system diseases that affect motor function.

Identifying brain regions for integrative sensorimotor processing with ankle movements

The objective of this study was to define cortical and subcortical structures activated during both active and passive movements of the ankle, which have a fundamental role in the physiology of locomotion, to improve our understanding of brain sensorimotor integration. Sixteen healthy subjects, all right-foot dominant, performed a dorsi-plantar flexion task of the foot using a custom-made wooden manipulandum, which enabled measurements of the movement amplitude. All subjects underwent a training session, which included surface electromyography, and were able to relax completely during passive movements. Patterns of activation during active and passive movements and differences between functional MRI (fMRI) responses for the two types of movement were assessed. Regions of common activation during the active and passive movements were identified by conjunction analysis. We found that passive movements activated cortical regions that were usually similar in location to those activated by active movements, although the extent of the activations was more limited with passive movements. Active movements of both feet generated greater activation than passive movements in some regions (such as the ipsilateral primary motor cortex) identified in previous studies as being important for motor planning. Common activations during active and passive movements were found not only in the contralateral primary motor and sensory cortices, but also in the premotor cortical regions (such as the bilateral rolandic operculum and contralateral supplementary motor area), and in the subcortical regions (such as the ipsilateral cerebellum and contralateral putamen), suggesting that these regions participate in sensorimotor integration for ankle movements. In future, similar fMRI studies using passive movements have potential to elucidate abnormalities of sensorimotor integration in central nervous system diseases that affect motor function.

Towards an understanding of gait control: brain activation during the anticipation, preparation and execution of foot movements

While a detailed understanding of brain activity with hand movements has developed, less is known about the functional anatomy of motor control for foot movements. Here we have used fMRI to define brain activity associated with unilateral foot extension and flexion, component movements of gait. We studied brain responses to visually cued active and passive movements and periods of either preparation (before active movement) or anticipation (before passive movement) with a pseudo-randomized block design. A mixed-effects (n = 12) contrast of the active movement condition vs. rest identified brain activation in regions including the medial wall of the primary sensorimotor cortex, consistent with expected somatotopy. Medial wall activation during passive movement vs. rest was less intense and localized to the same region. Frontal and association cortices were more active during preparation or anticipation periods than during the movements themselves. A contrast of preparation to move vs. active movement showed significant activation in the medial frontal and frontopolar gyri and the precuneus. Contrast of the anticipation of movement with the passive movement condition revealed activation in the dorsal premotor cortex and precuneus. Our study thus provides evidence for somatotopy in multiple functional regions in the motor control network. The anterior prefrontal activity is involved in the preparation for cued movement with distinct regions of the medial motor cortex (including SMA and CMA) preferentially involved in motor program planning and execution. This direct characterization of brain activation patterns associated with foot movements promises use of fMRI for the functional analysis of pathologies of gait.

The Effect of Heat Treatment on Chalcopyrite

The influence of conventional heat treatment and microwave radiation on chalcopyrite was investigated. There was a significant increase in the proportion of material recovered to magnetic fraction and magnetic susceptibility with conventional heating time. XRD analysis detected phase changes in conventional heat-treated chalcopyrite, which increases the magnetic susceptibility of the ore and enables its effective magnetic separation, which is impossible to achieve in its original state.

With microwave treatment, the magnetic susceptibility increases and the proportion of material recovered to magnetic fraction on the induced rolls is also increased. However, XRD analysis failed to detect any phase changes. A possible explanation for this observed behaviour is that the more magnetic component that has been formed by microwave treatment is below the threshold of detection of the XRD analyser. Taking into account that results from the froth flotation tests indicated that % weight fraction in the concentrate decreases with microwave exposure time, the change might be due to a surface effect.