A computed tomography-based planning tool for predicting difficulty of minimally invasive aortic valve replacement

Aortic Valve Replacement: Understanding Predictors for the Optimal Ministernotomy Approach

INTRODUCTION

The most common minimally invasive approach for aortic valve replacement (AVR) is the partial upper mini-sternotomy. The aim of this study is to understand which preoperative computed tomography (CT) features are predictive of longer operations in terms of cardio-pulmonary bypass timesand cross-clamp times.

METHODS

From 2011 to 2022, we retrospectively selected 246 patients which underwent isolated AVR and had a preoperative ECG-gated CT scan. On these patients, we analysed the baseline anthropometric characteristics and the following CT scan parameters: aortic annular dimensions, valve calcium score, ascending aorta length, ascending aorta inclination and aorta-sternum distance.

RESULTS

We identified augmented body surface area (>1.9 m2), augmented annular diameter (>23 mm), high calcium score (>2500 Agatson score) and increased aorta-sternum distance (>30 mm) as independent predictors of elongated operation times (more than two-fold).

CONCLUSIONS

Identifying the preoperative predictive factors of longer operations can help surgeons select cases suitable for minimally invasive approaches, especially in a teaching context.

Difficulty score for the treatment of isolated gingival recessions with the coronally advanced flap: a preliminary reliability study

OBJECTIVES

The treatment of gingival recessions (GRs) is operator-sensitive and dependent upon several local anatomical factors. The aim of this study was to introduce a difficulty score for the treatment of localized GRs with the coronally advanced flap (CAF) and to test its consistency among different operators.

MATERIALS AND METHODS

A rubric (difficulty score) consisting of the assessment and grading of 8 anatomical parameters (anatomical papilla, apical and lateral keratinized tissue width, apical and lateral frenum, vestibulum depth, scar tissue, and mucosal invagination) is described based on the available evidence and the authors' experience. Inter-examiner agreement, with the score, was tested on 32 localized GRs among four different experienced practitioners.

RESULTS

Minor discrepancies were observed in the total scores between the reviewers (intraclass correlation coefficient [ICC] 0.95). A good reproducibility, with ICCs ranging from 0.56 to 0.98, was found for the individual parameters. All models showed high absolute variance contribution conveying true differences among the cases, and small examiner variance, demonstrating minor systematic variability among the four reviewers and reproducible evaluations.

CONCLUSIONS

The proposed difficulty score for the treatment of GRs with CAF was reproducible among different operators. Clinical interventional studies are the next step to validate the clinical magnitude of the present score.

CLINICAL RELEVANCE

A novel tool for evaluating the difficulty of the treatment of isolated gingival recession using CAF was described. Clinicians can benefit from this score when assessing the expected level of complexity of the surgical case.

Eligibility for minithoracotomy aortic valve replacement: from Van Praet classification to complex scanner measurements

Van Praet proposed a classification to predict the ease of minithoracotomy aortic valve replacement (MT-AVR) based on the position of the aorta in the thorax. We have evaluated the relevance of complex computed tomography (CT) scan measurements to predict the ease of performing a MT-AVR. The first 57 patients who underwent MT-AVR from February 2018 to June 2020 were selected prior to surgery using Van Praet's IA and IB classes. We made additional measurements on aorta position related to the chest and the incision on the preoperative CT scan. The main objective was to correlate complex CT measurements with different operating durations. Van Praet criteria were significantly related to the distance from the center of the aorta to the midline (p value < 0.001), the distance from the center of the aortic ring to the midline (p value = 0.013) and aorto-sternal angle (p < 0.001). We did not find a correlation between CT criteria and the different surgical steps durations in patients belonging to Van Praet classes IA and IB. Our cohort of Van Praet class Ia and Ib patients were able to benefit from a MT-AVR without the need for conversion. Complex CT measurements do not provide additional information to predict surgical difficulties. This classification appears to be sufficient to determine a patient's eligibility for MT-AVR, even for a surgeon experienced in sternotomy in his first MT-AVR.

Minimal invasive aortic valve replacement: associations of radiological assessments with procedure complexity

Objectives

Limited aortic annulus exposure during minimal invasive aortic valve replacement (mini-AVR) proves to be challenging and contributes to procedure complexity, resulting in longer procedure times. New innovations like sutureless valves have been introduced to reduce procedure complexity. Additionally, preoperative imaging could also contribute to reducing procedure times. Therefore, we hypothesize that Computed Tomography (CT)-image based measurements are associated with mini-AVR complexity.

Methods

One hundred patients who underwent a mini-sternotomy and had a preoperative CT scan were included. With a CT-based mini-AVR planning tool, we measured access distance, access angle, annulus dimensions, and calcium volume. The associations of these measurements with cardiopulmonary bypass (CPB) time and aortic cross-clamp (AoX) time were assessed using univariable and multivariable regression models. In the multivariable models, these measurements were adjusted for age and suture technique.

Results

In the univariable regression models, calcium volume and annulus dimensions were associated with longer CPB and AoX time. After adjusting for age and suture technique, increasing calcium volume was still associated with longer CPB (adjusted β-coefficient 0.002, 95%-CI (0.005, 0.019), p-value = 0.002) and AoX time (adjusted β-coefficient 0.010, 95%-CI (0.004, 0.016), p-value = 0.002). However, after adjusting for these confounders, the association between annulus dimensions and procedure times lost statistical significance.

Conclusion

Increase in calcium volume are associated with longer CPB and AoX times, with age and sutureless valve implantation as independent confounders. In contrast to previous studies, access angle was not associated with procedure complexity.

Simulation of a Right Anterior Thoracotomy Access for Aortic Valve Replacement Using a 3D Printed Model

OBJECTIVE

The right anterior lateral thoracotomy (RALT) approach for aortic valve replacement provides excellent outcomes in expert hands while avoiding sternal disruption. It, however, remains a technically demanding niche operation. Instrument trajectories via this access are influenced by patient anatomy, the intercostal space chosen, and surgical retraction maneuvers.

METHODS

To simulate the typical surgical maneuvers, on an anatomically accurate model, and to measure the instrument trajectories, we generated a 3-dimensional (3D) printed model of the heart and chest cavity. A simulated approach to the base of the right coronary sinus via the medial-second intercostal, the lateral-second intercostal, or third intercostal space was made. Keeping the instrument in place, 3D scans of the models and geometrical measurements of the instrument trajectories were performed.

RESULTS

The 3D scans of the 3D printed model showed a high fidelity when compared to the original computed tomographic scan image geometry (mean deviation of 1.26 ± 1.27mm). The instrument intrathoracic distance was 75 mm via the medial-second, 115 mm via the lateral-second, and 80 mm via the third intercostal space. The 3D angulation of the instrument to the incision was 33.77^o, 55.93^o, and 38.4^o respectively. The distance of the instrument to the lateral margin was 12, 26, and 5 mm respectively. The cranial margin of the incision was always a limiting margin for the instrument.

CONCLUSIONS

Three-dimensional printing and 3D scanning facilitated a realistic simulation of the instrument trajectory during RALT approach. The lateral-second intercostal approach showed the most favorable approach angle and distance from the lateral margin, although it also had the longest intrathoracic distance.