Quantification of pectus excavatum: Anatomic indices

Utility of White Light Scanning as an Alternative to Computed Tomography to Evaluate Severity of Pectus Excavatum Deformity

BACKGROUND

Pectus excavatum (PE) severity and surgical candidacy are determined by computed tomography (CT)-delineated Haller Index (HI) and Correction Index (CI). White light scanning (WLS) has been proposed as a non-ionizing alternative. The purpose of this retrospective study is to create models to determine PE severity using WLS as a non-ionizing alternative to CT.

METHODS

Between November 2015 and February 2023, CT and WLS were performed for children ≤18 years undergoing evaluation at a high-volume, chest-wall deformity clinic. Separate quadratic discriminate analysis models were developed to predict CT HI ≥ 3.25 and CT CI ≥ 28% indicating surgical candidacy. Two bootstrap forest models were trained on WLS measurements and patient demographics to predict CT HI and CT CI values then compared to actual index values by intraclass correlation coefficient (ICC).

RESULTS

In total, 242 patients were enrolled (86.4% male, mean [SD] age 15.2 [1.3] years). Quadratic discriminate analysis models predicted CT HI ≥ 3.25 with specificity = 91.7%, PPV = 97.7% (AUC = 0.91), and CT CI ≥ 28% with specificity = 92.3%, PPV = 93.5% (AUC = 0.84). Bootstrap forest model predicted CT HI with training dataset ICC (95% CI) = 0.91 (0.88-0.93, R2 = 0.85) and test dataset ICC (95% CI) = 0.86 (0.71-0.94, R2 = 0.77). For CT CI, training dataset ICC (95% CI) = 0.91 (0.81-0.93, R2 = 0.86) and test dataset ICC (95% CI) = 0.75 (0.50-0.88, R2 = 0.63).

CONCLUSIONS

Using noninvasive and nonionizing WLS imaging, we can predict PE severity at surgical threshold with high specificity obviating the need for CT. Furthermore, we can predict actual CT HI and CI with moderate-excellent reliability. We anticipate this point-of-care tool to obviate the need for most cross-sectional imaging during surgical evaluation of PE.

LEVEL OF EVIDENCE

Level III.

STUDY TYPE

Study of Diagnostic Test.

Orthotopic heart transplantation in patient with situs inversus and pectus excavatum: a case report

BACKGROUND

Heart transplantation in patients with situs inversus is challenging, especially in terms of reconstruction of the systemic venous return. Several rerouting techniques have been presented but are associated with vulnerability to external compression, which might cause hemodynamic instability, especially in the presence of chest deformity. In this study, we report a rare case of successful heart transplantation in the presence of situs inversus and pectus excavatum.

CASE PRESENTATION

A 55-year-old man, with a history of surgeries for corrected transposition of the great arteries with ventricular septal defect, was registered for heart transplantation owing to progression of heart failure. Subsequently, he had undergone a left ventricular assist device implantation; 14 years after registration, he underwent transplantation of the heart with normal anatomy. The inferior vena cava was reconstructed by anastomosing the left atria with a counterclockwise rotation of the donor heart and by lengthening the recipient inferior vena cava with a conduit made of the residual right atrial tissue. The superior vena cava was reconstructed using a donor innominate vein harvested with sufficient length. After successful weaning from cardiopulmonary bypass, the chest could not be closed because the heart was compressed owing to chest deformity, resulting in hemodynamic instability. Therefore, to exclude the left lung, a left pericardial screen was created using a bovine pericardium, allowing the chest to be closed with acceptable hemodynamics. The patient suffered postoperatively from a higher venous pressure, suggesting an obstruction of venous return early after surgery. The obstruction gradually resolved, and the patient was transferred for rehabilitation.

CONCLUSIONS

Heart transplantation in the presence of situs inversus is challenging; moreover, the presence of pectus excavatum further complicates the procedure. The paradoxically larger left lung and chest deformity compressed and impaired reconstructed systemic venous return. Although intrathoracic exclusion of the left lung was effective, an intraoperative or early postoperative thoracoplasty for pectus excavatum was also a viable option. Patient-specific management is mandatory, depending on the anatomy.

Depth-Sensing-Based Algorithm for Chest Morphology Assessment in Children with Cerebral Palsy

This study introduced a depth-sensing-based approach with robust algorithms for tracking relative morphological changes in the chests of patients undergoing physical therapy. The problem that was addressed was the periodic change in morphological parameters induced by breathing, and since the recording was continuous, the parameters were extracted for the moments of maximum and minimum volumes of the chest (inspiration and expiration moments), and analyzed. The parameters were derived from morphological transverse cross-sections (CSs), which were extracted for the moments of maximal and minimal depth variations, and the reliability of the results was expressed through the coefficient of variation (CV) of the resulting curves. Across all subjects and levels of observed anatomy, the mean CV for CS depth values was smaller than 2%, and the mean CV of the CS area was smaller than 1%. To prove the reproducibility of measurements (extraction of morphological parameters), 10 subjects were recorded in two consecutive sessions with a short interval (2 weeks) where no changes in the monitored parameters were expected and statistical methods show that there was no statistically significant difference between the sessions, which confirms the reproducibility hypothesis. Additionally, based on the representative CSs for inspiration and expirations moments, chest mobility in quiet breathing was examined, and the statistical test showed no difference between the two sessions. The findings justify the proposed algorithm as a valuable tool for evaluating the impact of rehabilitation exercises on chest morphology.

Is chest radiography a valid alternative to computed tomography in evaluation of pectus excavatum?

BACKGROUND

Current pectus excavatum management includes a computed tomography scan to evaluate the correction index, whose superiority to the Haller Index in terms of specificity and sensibility is still under debate. Furthermore, several studies report interchangeability between the Haller Index as measured by computed tomography and as measured by X-radiograph; however, it is not clear whether this correlation also exists for the correction index. The aim of our study was to evaluate the correlation between measurements of the Haller Index and the correction index obtained by Computed Tomography and by X-radiograph.

METHODS

This prospective study included 31 patients with pectus excavatum (who underwent preoperative chest computed tomography and X-radiograph) and a control group of 31 patients (who presented no chest deformity and underwent the same exams for other unrelated causes). We measured Haller Index and correction index on both exams for both groups. To demonstrate any correlation between computed tomography scans and X-radiographs for the two indexes, the Pearson R correlation test, Bland-Altman analysis, and ANOVA nested test were performed.

RESULTS

Pearson's coefficient (0.829 with P<0.0001) and ANOVA nested test showed a significant correlation and similar results between the Haller Index and the correction index on computed tomography and on X-radiograph.

CONCLUSIONS

Significant correlation and similar results are shown in our study in the measurement of CI and HI on computed tomography and X-radiograph. Further studies including a larger number of patients may be warranted.

A preliminary study on the normal values of the thoracic Haller index in children

OBJECTIVES

The Haller index (HI) is widely utilized as a quantitative indicator to assess the extent of the pectus excavatum (PE) deformity, which is the most common chest wall abnormality in children. Both preoperative correction planning and postoperative follow-up need to be based on the standard of normal thoracic growth and development. However, there is currently no established reference range for the HI in children. Consequently, the goal of this study was to conduct a preliminary investigation of normal HI values among children to understand thoracic developmental characteristics.

METHODS

Chest computed tomography images obtained from January 2012 to March 2022 were randomly selected from the imaging system of the Children's Hospital of Chongqing Medical University. We divided the images of children into a total of 19 groups: aged 0-3 months (1 group), 4-12 months (1 group) and 1 year to 17 years (17 groups), with 50 males and 50 females, totaling 100 children in each group. HI was measured in the plane where the lowest point of the anterior thoracic wall was located and statistically analysed using SPSS 26.0 software.

RESULTS

A total of 1900 patients were included in the study. Our results showed that HI, transverse diameter and anterior-posterior diameter were positively correlated with age (P < 0.05). Using age as the independent variable and HI as the dependent variable, the best-fit regression equations were HI-male = 2.047 * Age0.054(R2 = 0.276, P<0.0001) and HI-female = 2.045 * Age0.067(R2 = 0.398, P<0.0001). Males had significantly larger thoracic diameters than females, and there was little difference in the HI between the 2 sexes.

CONCLUSIONS

The HI rapidly increases during the neonatal period, slowly increases during infancy and stops increasing during puberty, with no significant differences between the sexes.

(F)utility of preoperative pulmonary function testing in pectus excavatum to assess severity

PURPOSE

The utility of pulmonary function testing (PFT) in pectus excavatum (PE) has been subject to debate. Although some evidence shows improvement from preoperative to postoperative values, the clinical significance is uncertain. A high failure-to-completion rate for operative PFT (48%) was identified in our large institutional cohort. With such a high non-completion rate, we questioned the overall utility of PFT in the preoperative assessment of PE and sought to evaluate if other measures of PE severity or cardiopulmonary function could explain this finding.

METHODS

Demographics, clinical findings, and results from cardiac MRI, PFT (spirometry and plethysmography), and cardiopulmonary exercise tests (CPET) were reviewed in 270 patients with PE evaluated preoperatively between 2015 and 2018. Regression modeling was used to measure associations between PFT completion and cardiopulmonary function.

RESULTS

There were no differences in demographics, symptoms, connective tissue disorders, or multiple indices of pectus severity and cardiac deformation in PFT completers versus non-completers. While regression analysis revealed higher RVEF, LVEF, and LVEF-Z scores, lower RV-ESV/BSA, LV-ESV/BSA, and LV-ESV/BSA-Z scores, and abnormal breathing reserve in PFT completers vs. non-completers, these findings were not consistent across continuous and binary analyses.

CONCLUSIONS

We found that PFT completers were not significantly different from non-completers in most structural and functional measures of pectus deformity and cardiopulmonary function. Inability to complete PFT is not an indicator of pectus severity.

Automatic implant shape design for minimally invasive repair of pectus excavatum using deep learning and shape registration

Minimally invasive repair of pectus excavatum (MIRPE) is an effective method for correcting pectus excavatum (PE), a congenital chest wall deformity characterized by concave depression of the sternum. In MIRPE, a long, thin, curved stainless plate (implant) is placed across the thoracic cage to correct the deformity. However, the implant curvature is difficult to accurately determine during the procedure. This implant depends on the surgeon's expert knowledge and experience and lacks objective criteria. Moreover, tedious manual input by surgeons is required to estimate the implant shape. In this study, a novel three-step end-to-end automatic framework is proposed to determine the implant shape during preoperative planning: (1) The deepest depression point (DDP) in the sagittal plane of the patient's CT volume is automatically determined using Sparse R-CNN-R101, and the axial slice containing the point is extracted. (2) Cascade Mask R-CNN-X101 segments the anterior intercostal gristle of the pectus, sternum and rib in the axial slice, and the contour is extracted to generate the PE point set. (3) Robust shape registration is performed to match the PE shape with a healthy thoracic cage, which is then utilized to generate the implant shape. The framework was evaluated on a CT dataset of 90 PE patients and 30 healthy children. The experimental results show that the average error of the DDP extraction was 5.83 mm. The end-to-end output of our framework was compared with surgical outcomes of professional surgeons to clinically validate the effectiveness of our method. The results indicate that the root mean square error (RMSE) between the midline of the real implant and our framework output was less than 2 mm.

Evaluating Cardiac Lateralization by MRI to Simplify Estimation of Cardiopulmonary Impairment in Pectus Excavatum

BACKGROUND

The severity of pectus excavatum is classified by the Haller Index (HI) and/or Correction Index (CI). These indices measure only the depth of the defect and, therefore, impede a precise estimation of the actual cardiopulmonary impairment. We aimed to evaluate the MRI-derived cardiac lateralization to improve the estimation of cardiopulmonary impairment in Pectus excavatum in connection with the Haller and Correction Indices.

METHODS

This retrospective cohort study included a total of 113 patients (mean age = 19.03 ± 7.8) with pectus excavatum, whose diagnosis was verified on cross-sectional MRI images using the HI and CI. For the development of an improved HI and CI index, the patients underwent cardiopulmonary exercise testing to assess the influence of the right ventricle's position on cardiopulmonary impairment. The indexed lateral position of the pulmonary valve was utilized as a surrogate parameter for right ventricle localization.

RESULTS

In patients with PE, the heart's lateralization significantly correlated with the severity of pectus excavatum (p ≤ 0.001). When modifying HI and CI for the individual's pulmonary valve position, those indices are present with greater sensitivity and specificity regarding the maximum oxygen-pulse as a pathophysiological correlate of reduced cardiac function (χ² 10.986 and 15.862, respectively).

CONCLUSION

The indexed lateral deviation of the pulmonary valve seems to be a valuable cofactor for HI and CI, allowing for an improved description of cardiopulmonary impairment in PE patients.

Pectus excavatum in motion: dynamic evaluation using real-time MRI

OBJECTIVES

The breathing phase for the determination of thoracic indices in patients with pectus excavatum is not standardized. The aim of this study was to identify the best period for reliable assessments of morphologic indices by dynamic observations of the chest wall using real-time MRI.

METHODS

In this prospective study, patients with pectus excavatum underwent morphologic evaluation by real-time MRI at 3 T between January 2020 and June 2021. The Haller index (HI), correction index (CI), modified asymmetry index (AI), and modified eccentricity index (EI) were determined during free, quiet, and forced breathing respectively. Breathing-related differences in the thoracic indices were analyzed with the Wilcoxon signed-rank test. Motion of the anterior chest wall was analyzed as well.

RESULTS

A total of 56 patients (11 females and 45 males, median age 15.4 years, interquartile range 14.3-16.9) were included. In quiet expiration, the median HI in the cohort equaled 5.7 (4.5-7.2). The median absolute differences (Δ) in the thoracic indices between peak inspiration and peak expiration were ΔHI = 1.1 (0.7-1.6, p < .001), ΔCI = 4.8% (1.3-7.5%, p < .001), ΔAI = 3.0% (1.0-5.0%, p < .001), and ΔEI = 8.0% (3.0-14.0%, p < .05). The indices varied significantly during different inspiratory phases, but not during expiration (p > .05 each). Furthermore, the dynamic evaluation revealed three distinctive movement patterns of the funnel chest.

CONCLUSIONS

Real-time MRI reveals patterns of chest wall motion and indicate that thoracic indices of pectus excavatum should be assessed in the end-expiratory phase of quiet expiration.

KEY POINTS

• The thoracic indices in patients with pectus excavatum depend on the breathing phase. • Quiet expiration represents the best breathing phase for determining thoracic indices. • Real-time MRI can identify different chest wall motion patterns in pectus excavatum.

Pain management for the Nuss procedure: comparison between erector spinae plane block, thoracic epidural, and control

Objective

Pectus excavatum is a congenital deformity characterized by a caved-in chest wall. Repair requires surgery. The less invasive Nuss procedure is very successful, but postoperative pain management is challenging and evolving. New pain management techniques to reduce opioid reliance include the erector spinae plane (ESP) block. We retrospectively examined opioid consumption after Nuss procedure comparing three pain management techniques: ESP block, thoracic epidural (TE), and patient-controlled analgesia (PCA).

Methods

This retrospective cohort study compared pain management outcomes of three patient groups. Seventy-eight subjects aged 10–18 years underwent Nuss procedure at our institution between January 2014 and January 2020. The primary outcome measure was opioid consumption measured in morphine milligram equivalents. Secondary measures included pain ratings and length of stay (LOS). Pain was quantified using the Numeric Pain Rating Scale. Analysis of variance was performed on all outcome measures.

Results

Average cumulative opioid use was significantly lower in the ESP block (67 mg) than the TE (117 mg) (p=0.0002) or the PCA group (172 mg) (p=0.0002). The ESP block and PCA groups both had a significantly shorter average LOS (3.3 and 3.7 days, respectively) than the TE group (4.7 days). ESP block performed best for reducing opioid consumption and LOS. Reduced opioid consumption is key for limiting side effects. This study supports use of ESP block as a superior choice when choosing among the three postoperative pain management options that were evaluated.

Conclusion

ESP resulted in reduced opioid consumption postoperatively and shorter LOS than TE or PCA for patients undergoing the Nuss procedure for surgical repair of pectus excavatum.

Mini thoracic CT adequately determines Haller index and decreases radiation exposure in children with pectus excavatum

INTRODUCTION

The preoperative assessment of Pectus Excavatum (PE) is resource intensive. CT chest for the purpose of calculating a Haller index (HI) remains a central component and is necessary for third-party reimbursment for surgical correction. With the goal of minimizing radiation exposure, a strategy was introduced to perform a mini-Thoracic CT (mini-CT) for the calculation of HI.

OPERATIVE TECHNIQUE

The mini-CT was performed as follows: a radio-opaque marker (ROM) was placed at the clinical deepest point of the deformity. The CT was then columnated to scan 3 cm above and 3 cm below the ROM. HI was calculated according to previously described technique. Seven children with PE who underwent mini-CT were age and weight matched to 7 children with PE who underwent standard low dose CT chest during the same time period. Radiation doses were evaluated using dose length product (DLP) and effective dose (mSv) between the two groups. Significance of differences was determined using the students t-test. The DLP of mini-CT compared to chest-CT was 17.9 vs 48.9,mGycm respectively. (p< 0.001) The mSv of the mini-CT compared to chest-CT was 0.32 vs 0.88, sMV respectively. (p<0.001) Both DLP and mSv were reduced by 63% in children who received a mini-CT. All children obtained insurance authorization and underwent uncomplicated Nuss repair.

CONCLUSION

For children with pectus excavatum deformities the mini-Thoracic CT is an effective method to calculate the HI. Compard to the conventional low dose chest CT, the mini-CT strategy significantly reduces radiation exposure to the child by 63% with no impact on third-party authorizations or Nuss repair.

Autonomic nervous system dysregulation in response to postural change in patients with pectus excavatum in Taiwan: a pilot study

Background

Pectus excavatum (PE) negatively impacts psychological function, but its effect on autonomic nervous system (ANS) function has not been investigated. We evaluated ANS function following postural changes in patients with PE.

Methods

The participants were 14 healthy men (control group) and 20 men with PE (study group). Psychological function was assessed using the visual analog scale for pain, Brief Symptom Rating Scale-5, and Beck Depression Inventory-II. Sleep quality was evaluated using the Pittsburgh Sleep Quality Index (PSQI). ANS regulation in response to postural change was measured in the supine position and immediately after sitting. All measurements were compared between the control and study groups at baseline and between the study groups before and after Nuss surgery.

Results

At baseline, upon postural change, symptomatic activity increased in the control group (50.3–67.4%, p = 0.035) but not in the study group (55.0–54.9%, p = 0.654); parasympathetic activity decreased in the control group (49.7–32.6%, p = 0.035) but not in the study group (45.1–45.1%, p = 0.654); and overall ANS regulation increased in the control group (1.02–2.08, p = 0.030) but not in the study group (1.22–1.22, p = 0.322). In response to postural change after Nuss surgery in the study group, sympathetic activity increased (48.7–70.2%, p = 0.005), parasympathetic activity decreased (51.3–29.8%, p = 0.005), and overall ANS regulation increased (0.95–2.36, p = 0.012).

Conclusion

ANS function in response to postural change is dysregulated in patients with PE, which improved after Nuss surgery.

Trial registration ClinicalTrials.gov, ID: NCT03346876, November 15, 2017, retrospectively registered, https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S0007KGI&selectaction=Edit&uid=U0003JZU&ts=2&cx=cstxeg

Comparison of the Standard vs. Thoracoscopic Extrapleural Modification of the Nuss Procedure—Two Centers’ Experiences

Pectus excavatum is the most common congenital anterior chest wall deformity, with an incidence of 1:400 to 1:1000. Surgical strategy has evolved with the revolutionary idea of Donald Nuss, who was a pioneer in the operative correction of this deformity using minimally invasive surgery. The aim of this paper is to compare the preliminary results of pectus excavatum repair in two University Centers with a moderate number of patients using the standard Nuss procedure and its modification, the extrapleural thoracoscopic approach. The statistical analysis showed no significant difference for the patient’s age (14.52 ± 3.70 vs. 14.57 ± 1.86; p = 0.95) and the CT Haller index (4.17 ± 1.58 vs. 3.78 ± 0.95; p = 0.32). A statistically significant difference was noted for the duration of a pectus bar implant (2.16 ± 0.24 vs. 2.48 ± 0.68; p = 0.03) between the Maribor and Novi Sad Center. We report 14 complications (28%), including dislocation of the pectus bar (10%), pleural effusion (8%), wound inflammation (6%), pericarditis (2%) and an allergic reaction to the pectus bar (2%). Standard and thoracoscopic extrapleural Nuss procedures are both safe and effective procedures used to correct a pectus excavatum deformity. The choice of surgical procedure should be made according to a surgeon’s reliability in performing a particular procedure. Our study found no advantages of one procedure over the other.

Computed tomographic evaluation of pectus excavatum in 14 cats

Pectus excavatum (PE) is one of the most frequently reported chest deformities. However, limited studies are available with regard to its CT scan findings in cats. In the present research computed tomographic images of the thoraxes of 14 cats diagnosed with PE has been reviewed. This is one of the first studies exploring the use of CT to characterise PE in animals. The aim of this study was to present characteristic CT features of PE in cats. The introduction of new criteria for better assessing thoracic wall deformity–a correction index (CI) and an asymmetry index (AI)–was also proposed. The study revealed a high variety of morphological features of PE in cats. It was demonstrated that among the 14 cats: cranial PE (an atypical location) occurred in seven cats while seven cats had typical (caudal) PE, long PE occurred in five cats, while short PE had nine cats. Of the 14 cats included in the study eight showed symmetric PE, and asymmetric PE was found insix. Thoracic asymmetry was found in six cats. Six cats had sternal torsion. Based on the Vertebral Index moderate or severe PE was revealed in 11 animals. In the group of cats studied the CI ranged from 12.20 to 32.11. The magnitude of AI did not exceed 10% in any of the cats studied. The study confirmed statistically significant differences in the CI values between groups of cats with different degrees of PE severity (p = 0.02). CT examination showed many PE features that have not been discussed so far. The main benefit of CT examination is its ability to reveal asymmetric PE, thoracic asymmetry and sternal torsion. CI and AI provided a clinically useful tool to quantify thoracic wall deformity in order to obtain comparable results between cats with PE.

Prevalence and prognosis of pericardial effusion in patients affected by pectus excavatum: A case-control study

BACKGROUND

The presence of pectus excavatum(PEX) has been occasionally associated with pericardial effusion. Aim of the present study was to compare incidence and prognosis of pericardial effusion in a group of unselected patients with PEX vs a control group.

METHODS

From a prospective registry of consecutive patients who underwent chest CT for cardiovascular disease, subjects with a radiological diagnosis of PEX were retrospectively identified (cases); from the same registry patients (controls) without rib cage abnormalities were randomly selected, until a 1:2 ratio was reached. The presence of pericardial effusion at CT was quantified. Follow-up was obtained for a composite end-point: cardiac tamponade, need for pericardiocentesis, need for cardiac surgery for relapsing pericardial effusion.

RESULTS

A total of 43 patients with PEX (20 females) and a control group of 86 cases (31 females) without rib cage abnormalities were identified. Pericardial effusion evaluated at CT was significatively more prevalent in patients with PEX vs control group, 37.2% vs 13.9% (p < 0.001), respectively; four patients with PEX (9.3%) had at least moderate pericardial effusion vs no subjects among the controls (p = 0.004). PEX diagnosis was significantly associated to pericardial effusion at multi-variate analysis (OR95%CI 10.91[3.47-34.29], p < 0.001). At a mean follow-up of 6.5 ± 3.4 years no pericardial events were recorded.

CONCLUSION

Our findings support the higher prevalence of pericardial effusion in patients with PEX when compared to a control group. The absence of adverse pericardial events at follow-up suggest the good prognosis of these effusions, that in the appropriate clinical setting might not be considered "idiopathic".

The Severity of Pectus Excavatum Defect Is Associated With Impaired Cardiopulmonary Function

BACKGROUND

Repair of pectus excavatum has cosmetic benefits, but the physiologic impact remains controversial. The aim of this study was to characterize the relationship between the degree of pectus excavatum and cardiopulmonary dysfunction seen on cardiac magnetic resonance (CMR) imaging, cardiopulmonary exercise testing (CPET), and pulmonary function testing (PFT).

METHODS

A single-center analysis of CMR, CPET, and PFT was conducted. Regression models evaluated relationships between pectus indices and the clinical end points of cardiopulmonary function.

RESULTS

Data from 345 CMRs, 261 CPETs, and 281 PFTs were analyzed. Patients were a mean age of 15.2 ± 4 years, and 81% were aged <18 years. The right ventricular ejection fraction (RVEF) was <0.50 in 16% of patients, left ventricular ejection fraction (LVEF) was <0.55 in 22%, RVEF Z-score was < -2 in 32%, and the LVEF Z-score was < -2 in 18%. CPET revealed 33% of patients had reduced aerobic fitness. PFT results were abnormal in 23.1% of patients. Adjusted analyses revealed the Haller index had significant (P < .05) inverse associations with RVEF and LVEF.

CONCLUSIONS

The severity of pectus excavatum is associated with ventricular systolic dysfunction. Pectus excavatum impacts right and left ventricular systolic function and can also impact exercise tolerance. The Haller index and correction index may be the most useful predictors of impairment.

Anesthesia for Innovative Pediatric Surgical Procedures

Over the past few decades, there have been many advances in pediatric surgery, some using new devices (eg, VEPTR, MAGEC rods) and others using less invasive approaches (eg, Nuss procedure, endoscopic cranial suture release, minimally invasive tethered cord release). Although many of these procedures were initially met with caution or skepticism, continued experience over the past few decades has shown that these procedures are safe and effective. This article reviews the anesthetic considerations for these conditions and procedures.

Automatic assessment of Pectus Excavatum severity from CT images using deep learning

Pectus excavatum (PE) is the most common abnormality of the thoracic cage, whose severity is evaluated by extracting three indices (Haller, correction and asymmetry) from computed tomography (CT) images. To date, this analysis is performed manually, which is tedious and prone to variability. In this paper, a fully automatic framework for PE severity quantification from CT images is proposed, comprising three steps: (1) identification of the sternue's greatest depression point; (2) detection of 8 anatomical keypoints relevant for severity assessment; and (3) measurements' geometric regularization and extraction. The first two steps rely on heatmap regression networks based on the Unet++ architecture, including a novel variant adapted to predict 1D confidence maps. The framework was evaluated on a database with 269 CTs. For comparative purposes, intra-observer, inter-observer and intra-patient variability of the estimated indices were analyzed in a subset of patients. The developed system showed a good agreement with the manual approach (a mean relative absolute error of 4.41%, 5.22% and 1.86% for the Haller, correction, and asymmetry indices, respectively), with limits of agreement comparable to the inter-observer variability. In the intrapatient analysis, the proposed framework outperformed the expert, showing a higher reproducibility between indices extracted from distinct CTs of the same patient. Overall, these results support the feasibility of the developed framework for the automatic, accurate and reproducible quantification of PE severity in a clinical context.

Analysis of chest wall elevation after the Nuss procedure using 3D body scanning technique in patients with pectus excavatum

PURPOSE

For the evaluation of the chest wall deformity, we adopted a non-invasive 3D body scanning system. The objective of this study is to evaluate surgical effect on the whole thorax using 3D scanning technique before and after Nuss procedure.

METHODS

We performed 3D body scanning using Structure Sensor (Occipital Inc, USA) in 11 symmetric patients (average age 13 ± 3.2) under general anesthesia before and after Nuss procedure. Using the scanned data, the improved chest wall was analyzed using 3D-Rugle (Medic Engineering, Japan) imaging software. Preoperative and postoperative 3D data were super-imposed and a thoracic elevating distance in the line of the axial and sagittal section through the deepest point was calculated. Pre- and postoperative external sternal angle (ESA) were calculated from the scanned data.

RESULTS

Mean thoracic elevation distance at the deepest point was 38.6 ± 6.1 mm and it was 28.4 ± 5.1 mm and 19.4 ± 4.9 mm at 4 cm and 8 cm cranial side, respectively. Average ESA improved from 3.9 ± 1.6 degrees to 15.0 ± 1.1 degrees after the operation.

CONCLUSION

Chest depression was effectively elevated 39 mm at the deepest point after Nuss procedure. An indirect elevation effect by pectus bars was found on the wide area of the anterior chest.

Recurrence of pectus excavatum in long-term follow-up after the Nuss procedure in young children based on the radiographic Haller index

BACKGROUND/PURPOSE

To show the changes of the thorax after bar removal in young children with pectus excavatum in long-term postoperative follow-up.

METHODS

A total of 173 patients who underwent Nuss procedure under the age of 10 years from January 2005 to December 2013 and underwent bar removal were retrospectively reviewed. Then, Patients who were followed-up for more than 5 years after bar removal were selected and assessed. All patients were evaluated with the Haller index (HI) by chest computed tomography before the Nuss procedure. Follow-up after bar removal was done by two-view radiography. Radiographic HI (rHI) change was evaluated from before bar removal, to immediately after bar removal, and 3 years and 5 years after bar removal.

RESULTS

Forty-two patients (35 boys, 7 girls) were followed-up for more than 5 years after bar removal. The average age at the Nuss procedure was 6.1 ± 1.3 years, and the average HI was 5.07 ± 1.54. The average age at bar removal was 8.5 ± 1.2 years. The average rHI was 2.47 ± 0.33 before bar removal, 2.75 ± 0.50 immediately after bar removal, 3.24 ± 0.64 at 3 years after bar removal, and 3.46 ± 0.91 at 5 years after bar removal. The rHI value increased significantly between all periods.

CONCLUSIONS

The Nuss procedure for young children may have the risk of recurrence during growth after bar removal.

LEVEL OF EVIDENCE

Level IV.

Computer-aided diagnosis of pectus excavatum using CT images and deep learning methods

Pectus excavatum (PE) is one of the most common chest wall defects. Accurate assessment of PE deformities is critical for effective surgical intervention. Index-based evaluations have become the standard for objectively estimating PE, however, these indexes cannot represent the whole information of chest CT images and may associated with significant error due to the individual differences. To overcome these limitations, this paper developed a computer-aided diagnosis (CAD) system based on the convolutional neural network (CNN) to automatically learn discriminative features and classify PE images. We also adopted block-wise fine-tuning methods based on the transfer learning strategy to reduce the potential risk of overfitting caused by limited data and experimentally explored the best fine-tuning degree. Our method achieved a high level of classification accuracy with 94.76% for PE diagnosis. Furthermore, we proposed a majority rule-based voting method to provide a comprehensively diagnostic results for each patient, which integrated the classification results of the whole thorax. The promising results support the feasibility of our proposed CNN-based CAD system for automatic PE diagnosis, which paves a way for comprehensive assessments of PE in clinics.

Outpatient monitoring of Pectus Excavatum: a Neural Network-based approach

Pectus Excavatum (PE) is a congenital anomaly of the ribcage, at the level of the sterno-costal plane, which consists of an inward angle of the sternum, in the direction of the spine. PE is the most common of all thoracic malformations, with an incidence of 1 in 300-400 people. To monitor the progress of the pathology, severity indices, or thoracic indices, have been used over the years. Among these indices, recent studies focus on the calculation of optical measures, calculated on the optical scan of the patient's chest, which can be very accurate without exposing the patient to invasive treatments such as CT scans. In this work, data from a sample of PE patients and corresponding doctors' severity assessments have been collected and used to create a decision tool to automatically assign a severity value to the patient. The idea is to provide the physician with an objective and easy to use measuring instrument that can be exploited in an outpatient clinic context. Among several classification tools, a Probabilistic Neural Network was chosen for this task for its simple structure and learning mode.

Chondrotomy and sternotomy combined with the Nuss procedure for severe asymmetric pectus excavatum: how to do it

The correction of severe asymmetric pectus excavatum is still challenging, especially for adults with a rigid thorax. For the repair of asymmetric cases, we introduce our surgical techniques added to the Nuss procedure. Chondrotomy of the depressed and deformed costal cartilage to elevate the depressed side was performed in a 42-year-old female patient. The depressed chest wall was directly elevated using pectus bars. Her sternal rotation angle improved from 27° to 15° after bar removal. In a 26-year-old male patient, oblique sternotomy and chondrotomy were performed. The sternal rotation angle improved from 26° to 9° postoperatively. These techniques were effective for correcting severe asymmetric pectus excavatum in adults.

Pectus excavatum and scoliosis: a review about the patient's surgical management

Although Nuss procedure is performed with satisfactory results, there has been a controversy in the literature regarding the effect of a Nuss procedure on the spine. This review article aims to perform an updated overview of the literature about the effect of pectus excavatum correction at the spine and the management of patients with both pectus excavatum and scoliosis. Although acquired scoliosis has been rarely reported after a Nuss procedure, studies show that the Nuss procedure can have a beneficial effect in mild coexisting scoliosis especially when it is performed during the adolescence. The management of cases presented with both pectus excavatum and scoliosis depends on the severity of pre-operative scoliosis and demands detailed evaluation of the spine pre and postoperatively. In the rare condition of post-operative scoliosis following a Nuss procedure, the removal of the metallic bar and conservative measures may have satisfactory results on the spine.

External caliper-based measurements of the modified percent depth as an alternative to cross-sectional imaging for assessing the severity of pectus excavatum

BACKGROUND

Cross-sectional imaging (CSI) may be clinically unnecessary in the evaluation of pectus excavatum (PE). The purpose of our study was to prospectively evaluate the accuracy and reliability of the modified percent depth (MPD), derived from caliper-based external measurements, in identifying PE.

METHODS

Children 11-21 years old presenting for evaluation of PE or to obtain thoracic cross-sectional imaging for other indications were measured to derive the Modified Percent Depth. The Haller Index (HI) and Correction Index (CI) were calculated from CSI. Receiver-Operator Characteristic (ROC) analysis was used to compare the sensitivity and specificity of MPD, HI, and CI. Interrater reliability was assessed using Spearman's correlation coefficient and Cohen's Kappa coefficient.

RESULTS

Of 199 patients, 76 (38%) had severe PE. Median age was 16 years (range = 11-21). The median Modified Percent Depth was 21.4% (IQR = 16.2-26.3) among those with PE versus 4.1% (IQR = 1.7-6.4) in those without (p < 0.001). MPD ≥ 11% exhibited similar sensitivity and specificity to HI ≥ 3.25 and CI ≥ 10 for identifying PE (ROC 0.98 vs. 0.97 vs. 0.98, respectively, p = 0.41). With respect to interrater reliability, independent clinicians' caliper measurements exhibited 87% agreement when identifying MPD ≥ 11% (p < 0.001) with excellent correlation (Spearman's ρ > 0.71, p < 0.001).

CONCLUSION

Caliper-based, physical examination measurements of the Modified Percent Depth reliably identify pectus excavatum and represent an alternative to CSI-based measurements for the assessment of PE.

TYPE OF STUDY

Diagnostic test.

LEVEL OF EVIDENCE

Level II.

Physician-Estimated Depth as a Screening Tool for Computed Tomography Evaluation of Pectus Excavatum

BACKGROUND

Pectus excavatum (PE) is the most common congenital chest wall anomaly with a reported incidence of 1/300 to 1/400 live births and a male predominance. Preoperative evaluation of defect severity typically requires a calculation of the Haller index (HI) and/or correction index (CI) using computed tomography (CT) or x-rays. The purpose of this study was to determine whether physician-estimated depth (PED), a bedside screening tool, could be used to identify a subset of pediatric patients in whom CT was unnecessary.

METHODS

After institutional review board approval (IRB #032018-091), we retrospectively reviewed all patients with a diagnosis of PE between 2009 and 2018 at our academic pediatric center. Demographic information including age, sex, and body mass index were abstracted. Imaging was reviewed to obtain HI and CI and to retrospectively calculate PED. The PED is calculated at the bedside by measuring the depth of the pectus at the site of greatest depression relative to a horizontal surface laid across the deformity. For this retrospective study, we calculated the CT-derived PED by measuring the depth from the horizontal on the respective CT images. Patients without imaging studies and patients with pectus carinatum, arcuatum, or mixed deformities were excluded from this study.

RESULTS

A total of 94 patients met inclusion criteria. Of these, 82% were male, with a median age of 15 y. Patients were further subdivided by BMI, with 46% of patients having a BMI of <18.5 kg/m² (i.e., underweight), whereas 54% of patients had a BMI of ≥18.5 kg/m². Using a threshold PED of 2 cm, patients with a BMI of <18.5 kg/m² had correct classification rates of 93% and 95% using PED relative to HI and CI, respectively. Patients with a BMI of ≥18.5 kg/m² had correct classification rates of 80% and 88% using PED relative to HI and CI, respectively, at the same 2 cm threshold.

CONCLUSIONS

PED is a viable screening tool for the preoperative evaluation of PE with a 2 cm threshold providing the combination of high sensitivity, specificity, and correct classification rates especially in underweight patients.

Sternal torsion in pectus excavatum is related to cardiac compression and chest malformation indexes

BACKGROUND/PURPOSE

The role of sternal torsion (ST) in patients with pectus excavatum (PEX) is unknown. We evaluated the relationship between ST and both chest malformation and cardiac compression (CC) indexes.

METHODS

We included consecutive patients with PEX who underwent chest computed tomography and cardiac magnetic resonance (CMR) to define surgical candidacy. Malformation indexes included the Haller index (HI), correction index (CI), and ST. CC and the tricuspid to mitral annulus width ratio were evaluated using CMR.

RESULTS

One-hundred and sixteen patients were included, with a mean HI of 5.8 ± 3.6 and a mean CI of 35.8 ± 18.0%. ST was significantly related to malformation indexes, being patients with absence of ST those showing the lowest HI (p = 0.048) and CI (p = 0.002). Right-sided ST was significantly related to the CC classification (p = 0.0001), and the tricuspid/mitral annulus width ratio was significantly lower among these patients (absence 0.98 ± 0.15, left-sided 0.91 ± 0.10, right-sided 0.80 ± 0.15, p < 0.0001). A significant inverse relationship between ST degrees and the tricuspid/mitral ratio was also identified (r = -0.47, p < 0.0001).

CONCLUSIONS

We identified a significant relationship between ST and both chest malformation and CC indexes; the absence of ST being identified as a marker of an overall more benign phenotype.

TYPE OF STUDY

Study of diagnostic test.

LEVEL OF EVIDENCE

Level II.

Impact of pectus excavatum on cardiac morphology and function according to the site of maximum compression: effect of physical exertion and respiratory cycle

Aims

Previous studies have demonstrated diverse cardiac manifestations in patients with pectus excavatum (PEX), although mostly addressing morphological or physiological impact as separate findings. Using multimodality imaging, we evaluated the impact of PEX on cardiac morphology and function according to the site of maximum compression, and the effect of exertion and breathing.

Methods and results

All patients underwent chest computed tomography, cardiac magnetic resonance (CMR), and stress echocardiography (echo) in order to establish surgical candidacy. We evaluated diastolic function and trans-tricuspid gradient during stress (echo); and systolic function and respiratory-related septal wall motion abnormalities (CMR). Patients were classified according to the site of cardiac compression as type 0 (without cardiac compression); type 1 (right ventricle); and type 2 [right ventricle and atrioventricular (AV) groove]. Fifty-nine patients underwent multimodality imaging, with a mean age of 19.5 ± 5.9 years. Compared with a sex and age matched control group, peak exercise capacity was lower in patients with PEX (8.4 ± 2.0 METs vs. 15.1 ± 4.6 METs, P &lt; 0.0001). At stress, significant differences were found between groups regarding left ventricular E/A (P = 0.004) and e/a ratio (P = 0.005), right ventricular E/A ratio (P = 0.03), and trans-tricuspid gradient (P = 0.001). At CMR, only 9 (15%) patients with PEX had normal septal motion, whereas 17 (29%) had septal flattening during inspiration. Septal motion abnormalities were significantly related to the cardiac compression classification (P &lt; 0.0001).

Conclusions

The present study demonstrated that patients with PEX, particularly those with compression affecting the right ventricle and AV groove, manifest diverse cardiac abnormalities that are mostly related to exertion, inspiration, and diastolic function.

The Nuss procedure for repair of pectus excavatum: 20 error traps and a culture of safety

In 1998, Donald Nuss changed the way the world thought about the surgical repair of pectus excavatum. The new operation adheres to sound orthopedic fundaments, but has a significantly higher learning curve than other operations in pediatric surgery. Variations in pectus excavatum type, severity, symmetry and chest wall pliability bring challenges. This article will detail common error traps and ways to avoid them when performing the Nuss procedure. As recent publications have shown, an operation done more than 50,000 times across the world may bring to light infrequent but devastating outcomes that may be preventable. The critical view of safety for pectus repair is discussed, as are areas where a culture of safety could optimize results on a larger scale. We will review potential opportunities to improve outcomes by identifying error traps in the preoperative, intraoperative, and postoperative care of patients undergoing the Nuss procedure.

Pectus excavatum repair using bridge fixation system

Background

The stability of the pectus bar is an important determinant of the success of pectus excavatum repair surgery. In practice, several different types of fixation method are in use for stabilizing pectus bars. The aim of this study was to compare the performance of the bridge fixation system with previous fixation systems for stabilizing pectus bars.

Methods

We performed a retrospective review of 1760 pectus excavatum repair cases conducted in the Thoracic Department of Choray Hospital and its satellite hospitals, between 2007 and 2017. We compared the results of 560 patients who had the bridge fixation system with the previous 1200 patients who had other fixation techniques.

Results

The bridge fixation system with 2 bars in 560 patients gave better results in terms of bar stabilization, operative time, and postoperative complications, compared to the previous 1200 patients who had other stabilization techniques. The average skin-to-skin surgery time using the bridge fixation system was 55 min. Of the 560 cases, only one patient showed trivial one bar dislocation, and one had a postoperative complication (pneumothorax).

Conclusions

We found the bridge fixation system to be superior not only in terms of stabilizing the bars but also for minimizing the time of surgery and postoperative complications, compared to other fixation systems. The bridge fixation system with 2 bars showed excellent results. Use of 3 bars is not necessary. One bar was used in the other fixation techniques and the results were found to be inferior compared to those using 2 bars.