Mitral valve analysis adding a virtual semi-transparent annulus plane for detection of prolapsing segments

Mitral valve surgery assisted by virtual and augmented reality: Cardiac surgery at the front of innovation

BACKGROUND

Given the variety in mitral valve (MV) pathology and associated surgical techniques, extended reality (XR) holds great potential to assist MV surgeons. This review aims to systematically evaluate the currently available evidence investigating the use of XR and associated technologies in MV surgery.

METHODS

A systematic database search was conducted of original articles and case reports that explored the use of XR and MV surgery in EMBASE, MEDLINE, Cochrane database and Google Scholar, from inception to February 2022.

RESULTS

Our search yielded 171 articles, of which 15 studies were included in this review, featuring 328 patients. Two main areas of application were identified: (i) pre-operative planning and (ii) predicting post-operative outcomes. The articles reporting outcomes relating to pre-operative planning were further categorised as exploring themes relevant to (i) mitral annular assessment; (ii) training; (iii) evaluation of surgical technique; (iv) surgical approach or plan and (v) selecting ring size or type. Preoperatively, XR has been shown to evaluate mitral annular pathology more accurately than echocardiography, informing the surgeon about the optimal surgical technique, approach and plan for a particular patient's MV pathology. Furthermore, XR could simulate and aid ring size/type selection for MV annuloplasty, creating a personalized surgical plan. Additionally, XR could estimate the postoperative MV biomechanical and physiological characteristics, predicting and pre-empting post-operative complications.

CONCLUSION

XR demonstrated promising applications for assisting MV surgery, enhancing outcomes and patient-centred care, nevertheless, there remain the need for randomized studies to ascertain its feasibility, safety, and validity in clinical practice.

Mitral Annular Elasticity Determines Severity of Regurgitation in Barlow's Disease

AIMS

Barlow's disease (BD) with late systolic mitral regurgitation provides diagnostic and therapeutic challenges. The mechanisms of the regurgitation are still unclear. We hypothesized that the onset and the severity of late systolic regurgitation are determined by annulus dynamics and the mechanical stresses imposed by the left ventricle.

METHODS AND RESULTS

Ten patients with BD and mitral annulus disjunction (MAD) were compared with ten healthy controls. Resting blood pressure (BP) was measured and transthoracic three-dimensional (3D) echocardiography was analyzed using a holographic display that allows tracking and measurements of mitral annulus surface area (ASA) throughout the cardiac cycle. A novel annulus elastance index (dASA/dP) was calculated between aortic valve opening and onset of mitral regurgitation. Severity of MAD was quantified as the disjunction index (mm*degree). Leaflet coaptation area was calculated using a finite element model. Peak systolic ASA in controls and patients were 9.3±0.6 and 21.1±3.1 cm², respectively (p<0.001). In patients ASA increased rapidly during LV ejection and onset of mitral regurgitation coincided closely with peak upslope of annulus area change (dASA/dt). The finite element model showed a close association between rapid annulus displacement and coaptation area deficit in BD. Systolic annulus elastance index (0.058±0.036 cm²/mmHg) correlated strongly with disjunction index (r=0.91, p<0.0001). Moreover, regurgitation volume showed a positive correlation with systolic BP (r=0.80, p<0.01) CONCLUSION: The present pilot study supports the hypothesis that annulus dilatation may accentuate mitral valve regurgitation in patients with Barlow's disease. A novel annulus elastance index may predict the severity of mitral valve regurgitation in selected patients.

Artificial Intelligence in Echocardiography for Anesthesiologists

Echocardiography is a unique diagnostic tool for intraoperative monitoring and assessment of patients with cardiovascular diseases. However, there are high levels of interoperator variations in echocardiography interpretations that could lead to inaccurate diagnosis and incorrect treatment. Furthermore, anesthesiologists are faced with the additional challenge to interpret echocardiography and make decisions in a limited timeframe from these complex data. The need for an automated, less operator-dependent process that enhances speed and accuracy of echocardiography analysis is crucial for anesthesiologists. Artificial intelligence is playing an increasingly important role in the medical field and could help anesthesiologists analyze complex echocardiographic data while adding increased accuracy and consistency to interpretation. This review aims to summarize practical use of artificial intelligence in echocardiography and discusses potential limitations and challenges in the future for anesthesiologists.

Validation of a Holographic Display for Quantification of Mitral Annular Dynamics by Three-Dimensional Echocardiography

BACKGROUND

Three-dimensional (3D) echocardiography with multiplanar reconstruction (MPR) is used clinically to quantify the mitral annulus. MPR images are, however, presented on a two-dimensional screen, calling into question their accuracy. An alternative to MPR is an autostereoscopic holographic display that enables in-depth visualization of 3D echocardiographic data without the need for special glasses. The aim of this study was to validate an autostereoscopic display using sonomicrometry as a gold standard.

METHODS

In 11 anesthetized open-chest pigs, sonomicrometric crystals were placed along the mitral annulus and near the left ventricular apex. High-fidelity catheters measured left atrial and ventricular pressures. Adjustments of pre- and afterload were done by constriction of the inferior vena cava and the ascending aorta, respectively. Three-dimensional epicardial echocardiography was obtained from an apical view and converted to the autostereoscopic display. A 3D virtual semitransparent annular surface (VSAS) was generated to measure commissure width (CW), septal-lateral length, area of the mitral annular surface, nonplanarity angle, and the annular height-to-commissure width ratio in mid-systole and late diastole.

RESULTS

Mitral annular measurements from the 3D VSAS derived from the 3D echocardiographic images and autostereoscopic display correlated well with sonomicrometry over a range of loading conditions: CW length (r = 0.98, P < .00001), septal-lateral length (r = 0.98, P < .00001), annular surface area (r = 0.93, P < .001), nonplanarity angle (r = 0.87, P < .001), and annular height-to-commissure width ratio (r = 0.85, P < .01). The 3D VSAS showed better agreement with the sonomicrometric measurements compared with MPR.

CONCLUSIONS

Mitral annular measurements using 3D VSAS correlate well with sonomicrometry over a range of loading conditions and may represent a powerful tool for noninvasive quantification of mitral annular dynamics.