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

Abstract

BackgroundWe hypothesized that a novel three-dimensional virtual semi-transparent annulus plane (3D VSAP) presented on a holographic screen can be used to visualize the prolapsing tissue in degenerative mitral valve disease and furthermore, provide us with geometrical data of the mitral valve apparatus. Phantom and patient studies were designed to demonstrate the feasibility of creating a semi-automatic, semi-transparent mitral annulus plane visualized on a holographic display.MethodsTen pipe cleaners mimicking the mitral annulus with different shapes and three types of annuloplasty rings served as phantoms. We obtained 3D transoesophageal examination of the phantoms in a special designed box filled with water. Recordings were converted to the holographic display and a 3D VSAP was created. The ratio of the major and minor axes as well as the non-planar angles were calculated and compared with direct measures of the phantoms. Forty patients with degenerative mitral valve disease were then analyzed with 3D transthoracic echocardiography (TTE) and a 3D VSAP was created on the holographic display. A total of 240 segments were analyzed by two independent observers, one echo expert (observer I), and the other novice with limited echo experience (observer II). The two observers created the 3D VSAP in each patient before suggesting the valve pathology.ResultsThe major/minor axes ratio and non-planar angles by 3D VSAP correlated with direct measurements by r = 0.65, p < 0.02 and r = 0.99, p < 0.0001, respectively. The sensitivity and specificity of the 3D VSAP method in patients was 81 and 97 %, respectively (observer I) and for observer II 77 and 96 %, respectively. The accuracy and precisions were 93.9 and 89.4 %, respectively (observer I), 92.3 and 85.1 % (observer II). Mitral valve analysis adding a 3D VSAP was feasible with high accuracy and precision, providing a quick and less subjective method for diagnosing mitral valve prolapse. This novel method may improve preoperative diagnostics and may relieve a better understanding of the pathophysiology of mitral valve disease. Thus, based on the specific findings in each patient, a tailored surgical repair can be planned and hopefully enhance long-term repair patency in the future.

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

“…As MV pathology can vary substantially between patients, improved visualisation and understanding of the MV conformation pre-operatively using XR may have a role in informing clinical decision making. Estimation of extent of MR using a 3D virtual semi-transparent annulus plane (3D VSAP) model presented on a holographic screen was also found to be in good agreement with intra-operative findings of the ratio of annular major/minor axes and non-planar angles by Dumont et al 11 In this context, as well as informing assessment of MV pathology, use of XR modelling also enabled MV annular assessment to be conducted more quickly thus saving surgeon’s time and resources as well as optimising selection of MV repair technique. In addition, alongside the MV annulus, Walczak et al 16 investigated an XR model which also encompassed the chordae tendinae, the lengths of which could be adjusted to simulate MV coaptation or prolapse.…”

“…Three studies 10,11,16 were included which explored the use of XR technology in assessment of the pathological MV annulus pre-operatively. One of these papers 12 also reported outcomes relevant to selection of the annuloplasty ring size or type as well as prediction of post-operative outcomes.…”

“…Reaching beyond the use of XR MV modelling pre-operatively, Dumont et al 11 also highlighted the use of such XR technology in the intra-operative environment, following MV ring implantation but whilst the patient is still on the table. Utilisation of XR in this manner may enable residual to prolapse to be identified in real-time, with the patient still under general anaesthesia, rather than retrospectively and hence enable this to be amended at the earliest opportunity if appropriate.…”

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

“…A nest of gauze put gently onto the anterior wall was filled with ultrasound gel to ensure some distance between the epicardium and the transducer ( Figure 3A). Data sets were stored and exported to a separate workstation connected to an autostereoscopic screen (Setred, Oslo, Norway) for further analysis 12,13 (Figures 3B and 3C). Measurements were obtained in mid-systole, defined as the frame halfway between end-diastole (R wave on the electrocardiogram) and closure of the aortic valve and late diastole, defined as the frame immediately after the onset of the P wave or before atrial contraction.…”

“…We have recently demonstrated the feasibility of analyzing mitral valve pathology using the autostereoscopic display. 12,13 A 3D virtual semitransparent annular surface (VSAS) has been developed to enhance visualization of prolapsing segments and annular geometric measurements on the autostereoscopic display. The aim of the present study was to validate the 3D VSAS method in an acute anesthetized open-chest pig model using sonomicrometry as a reference method.…”