New Computerized Planning Algorithm and Clinical Testing of Optimized Nuss Bar Design for Patients with Pectus Excavatum.

BACKGROUND Computer-aided design (CAD) has been used in the Nuss procedure to determine the bar length and shape. Despite computer aid, the shape and design remain quite intuitive. We tested a new algorithm to determine the optimal bar shape. MATERIAL AND METHODS The normal sterno-vertebral distance was defined on computed tomography (CT) scans of patients without pectus excavatum (PEx) at the same level where the deepest depression was found on CT scans of 97 patients with PEx. Four points were marked on the CT scan of 60 patients with PEx at the deepest deformity: P1: edge of the vertebra; P2: edge of the deformity; P3: the expected contact point of the bar and the rib; and P4: the expected end of the bar. The algorithm generated 3 circles upon these points, and the fusion of the arcs drew the line of the ideal bar. Corrected and normal sterno-vertebral distance values were compared with the Mann-Whitney U test. Ten bars were bent manually guided by a 1: 1 printout of the designed bar and were implanted in 10 adolescents. RESULTS The shortest sterno-vertebral distance was 3 cm below the intermammillary line in PEx patients. The normal mean sterno-vertebral distance at this level was 10.16±1.35 cm in non-PEx patients. The mean virtually corrected sterno-vertebral distance was 10.28±1.27 cm. No significant difference was found (P=0.44). The bars were seamless and were successfully implanted. No bar needed adjustment, the operation time was shorter, and the patient satisfaction score was 9.4/10. CONCLUSIONS With our new algorithm, an optimal Nuss bar can be designed.

Sternal cleft and pectus excavatum: an overlooked congenital association?

BACKGROUND: Sternal cleft (SC), a rare thoracic malformation, is associated with pectus excavatum (PE) in 2.6-5% of cases. It remains unclear if these conditions are congenitally linked or if SC repair triggers PE. To investigate the potential higher frequency of PE in SC cases, we conducted a retrospective study of our SC patients. METHODS: We assessed PE incidence, progression, and management in SC patients treated at our institute from 2006 to 2022. When available, we collected pre-SC repair CT scan data, calculating the Haller Index (HI) and Correction Index (CI) and compared them to a selected control group. RESULTS: Among 8 SC patients, 7 had concomitant PE (87.5%), varying in severity. PE management ranged from observation to thoracoplasty, depending on its degree. We observed a significant pre-operative CI difference between SC and control group patients (p < 0.00001). In the last two SC repair cases, we attempted concurrent PE prevention or treatment. CONCLUSION: Our findings suggest an underestimated association between PE and SC in the existing literature. SC patients may exhibit a predisposition to PE from birth, which may become more apparent with growth after SC repair. Consequently, PE prevention or treatment should be considered during SC repair procedures.

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.

Evaluating Skeletal Maturity at Time of Surgical Correction of Pectus Excavatum Based on Medial Clavicle Epiphyseal Ossification.

BACKGROUND: Surgical correction of pectus excavatum (SCOPE) is dependent upon chest wall pliability with optimal timing prior to complete skeletal maturation. Measures of skeletal maturity are not readily available for operative planning; therefore, surgeons use age as proxy despite patient-specific rates of skeletal maturation. We aimed to determine whether preoperative skeletal maturity is associated with postoperative pain as surrogate for chest wall pliability. METHODS: Children ≤18 years who underwent SCOPE from 2020 to 2022 were retrospectively identified. Preoperative CT within 3 months of procedure was reviewed by 2 radiologists and 1 surgeon. Skeletal maturity was determined by Schmeling-Kellinghaus classification which stages secondary epiphyseal ossification of the medial clavicle. Inter-rater reliability was evaluated. Schmeling-Kellinghaus stage and postoperative pain were compared. RESULTS: Of twenty-eight records reviewed, 57% were Schmeling-Kellinghaus stage 1. High inter-rater reliability was identified (inter-radiologist: kappa = .95, P < .001, all raters: kappa = .78, P < .001). Median age at operation was 15.5 years (interquartile range: 14.8-16.0) and increased with skeletal maturity (P < .001). When comparing stage 1 (n = 16) to >1 (n = 12), stage 1 had lower maximum pain scores (P < .001), total morphine equivalents (P < .001), and benzodiazepine use (P < .001) after surgery. CONCLUSIONS: The Schmeling-Kellinghaus classification system is a valid proxy of skeletal maturity that can be applied with high inter-rater reliability. SCOPE during stage 1 was found to have less postoperative pain and narcotic use than more mature stages. This is proof of concept that skeletal maturity should be considered when determining optimal timing of surgical correction. Future research will evaluate the impact of skeletal maturity on postoperative outcomes.

Use of Transesophageal Echocardiography for Enhanced Safety During Bar Removal Procedures After Minimally Invasive Repair of Pectus Excavatum.

Background: Minimally invasive repair of pectus excavatum involves placement of retrosternal support (Nuss) bars. Hardware removal has been rarely associated with life-threatening hemorrhage from the heart, aorta, internal mammary arteries, and/or lung. There is no accepted standard intraoperative monitoring technique used during removal. We hypothesized that the use of transesophageal echocardiography (TEE) during Nuss bar removal would enhance safety of the procedure and be cost-effective. Methods: IRB-approved retrospective review of patients who underwent Nuss bar removal with intraoperative TEE monitoring over a 4-year period, from March 2013 to May 2017, was completed. Bar removal procedures were performed supine, under general anesthesia. TEE images were monitored and any distortion of the cardiac silhouette, new pericardial effusion, and/or cardiac arrhythmias would be considered evidence of possible bar adherence, triggering possible conversion to sternotomy or thoracotomy. Results: In total, 87 consecutive patients, mean age of 20 years, were identified. Bars had been in place for a mean of 30 months. Average procedure time was 67 minutes. No patients experienced arrhythmias, cardiac injury, or significant hemorrhage during removal. TEE gave excellent visualization of the cardiac silhouette and pericardium in all cases. No patient required insertion of an arterial line, a postoperative chest X-ray, or overnight hospitalization. Patients were discharged from the recovery room an average of 89 minutes postprocedure. Conclusion: TEE offers a minimally invasive safe way to visualize the pericardium and its contents during Nuss bar removal. Significant cardiac/mediastinal injuries should be immediately visible. The use of TEE is cost-effective and allows safe discharge the day of surgery.

A novel in silico Nuss procedure for pectus excavatum patients.

The purpose of this study is to suggest a novel in silico Nuss procedure that can predict the results of chest wall deformity correction. Three-dimensional (3D) geometric and finite element model of the chest wall were built from the 15-year-old male adolescent patient's computed tomography (CT) image with pectus excavatum of the mild deformity. A simulation of anterior translating the metal bar (T) and a simulation of maintaining equilibrium after 180-degree rotation (RE) were performed respectively. A RE simulation using the chest wall finite element model with intercostal muscles (REM) was also performed. Finally, the quantitative results of each in silico Nuss procedure were compared with those of postoperative patient. Furthermore, various mechanical indicators were compared between simulations. This confirmed that the REM simulation results were most similar to the actual patient's results. Through two clinical indicators that can be compared with postoperative patient and mechanical indicators, the authors consider that the REM of silico Nuss procedure proposed in this study is best simulated the actual surgery.

Description of a new clinical syndrome: thoracic constriction without evidence of the typical funnel-shaped depression-the "invisible" pectus excavatum.

Pectus excavatum (PE) is a congenital malformation with a funnel-shaped depression of the sternum that can lead to cardiac symptoms. However, there are patients with thoracic constriction (defined as elevated Haller-Index > 3.25 determined by cardiac magnetic resonance imaging (CMR)) without visible evidence of PE, leading to similar complaints. Between January 2004 till June 2020, patients who underwent CMR for further evaluation of the heart, due to cardiac symptoms were enrolled and compared to controls. Biventricular global strain analysis was assessed using feature tracking (CMR-FT). ECG and/or Holter recordings were performed to detect rhythm events. Cardiac symptoms were evaluated in detail using a questionnaire. Finally, 88 patients (male 35, female 53) with elevated Haller-Index (3.9 ± 0.8) were included and compared to CMR data from 25 individuals with confirmed PE and 25 healthy controls (HC). Mean age at time of CMR was 35 ± 16 years. The most common symptoms at presentation were palpitations (41%), followed by dyspnea (24%) and atypical chest pain (14%). Three patients (3%) had atrial fibrillation or atrial flutter. Concomitant phenomena were pericardial effusion in 39% and mitral valve prolapse (MVP) in 27% of the study cohort. While there were no differences in left ventricular function or volumes, right ventricular function (RVEF) was significantly lower in patients with internal PE compared to HC (RVEF (%) 50 ± 5 vs 59 ± 4, p < 0.01). Strain analysis revealed only discrete changes in RV strain, implying a purely mechanical problem in the absence of structural changes. RV dimensions were negatively correlated with the size of thoracic indices (r = 0.41), reflecting the extent of thoracic constriction. MVP was more prevalent in patients with greater thoracic indices (r = 0.24). The described cohort, referred to as internal PE because of the absence of external changes, showed similar CMR morphologic findings as patients with real PE (especially altered dimensions of the right heart and a lower RVEF). In addition, there was a high incidence of rhythm disturbances, such as extrasystoles or arrhythmias. In one-third of the study cohort additional abnormalities such as pericardial effusion or MVP were present, with MVP being found more frequently in patients with larger thoracic indices, suggesting a possible common pathogenesis.Trial registration: ISRCTN registry, ISRCTN15355937, retrospectively registered 03.06.2022, https://www.isrctn.com/ISRCTN15355937?q=15355937&filters=&sort=&offset=1&totalResults=1&page=1&pageSize=10 .

Cardiac anomalies in pediatric patients with pectus excavatum.

OBJECTIVE: Pectus excavatum is the most prevalently encountered deformity of the thoracic wall. It can be accompanied by congenital anomalies. METHODS: The cardiac findings of 36 children who were diagnosed at the Thoracic surgery outpatient clinic of our university between 10 February 2021 and 1 October 2021 and 57 healthy children in a similar age group were analyzed. RESULTS: We determined that the pectus excavatum patients in our study had a higher risk of having mitral insufficiency, mitral valve prolapse, tricuspid valve prolapse, cardiac malposition, and congenital heart disease. CONCLUSION: Our study showed that the prevalence of cardiac pathologies was higher in pediatric pectus excavatum patients than in healthy children in the control group. Thus, we recommend clinicians to refer pediatric pectus excavatum patients to pediatric cardiology outpatient clinics for the early diagnosis of potential cardiac pathologies.

The influence of pectus excavatum on cardiac kinetics and function in otherwise healthy individuals: A systematic review.

BACKGROUND: A number of anterior chest wall deformities, most notably pectus excavatum (PE), may have a detrimental effect on cardiac motion and function. Interpretation of transthoracic echocardiography (TTE) and speckle-tracking echocardiography (STE) results may be hampered by the possible influence of PE on cardiac kinetics. METHODS: A comprehensive search of all articles assessing cardiac function in PE individuals was carried out. Inclusion criteria were: 1) individuals aged >10 years; 2) studies providing objective assessment of chest deformity (Haller index). Studies that measured myocardial strain parameters in PE patients were also included. RESULTS: The search (EMBASE and Medline) yielded a total of 392 studies, 36 (9.2%) of which removed as duplicates; a further 339 did not meet inclusion criteria. The full-texts of 17 studies were then analyzed. All studies concordantly reported impaired right ventricular volumes and function. With respect to left ventricle (LV), TTE studies uniformly demonstrated a significant impairment in conventional echoDoppler indices in PE individuals, whereas STE studies provided conflicting results. Importantly, LV functional alterations promptly reverted upon surgical correction of chest defect. In subjects with PE of mild-to-moderate severity, we observed that degree of anterior chest wall deformity, as noninvasively assessed by modified Haller index (MHI), was strongly associated with myocardial strain magnitude, in heterogenous cohorts of otherwise healthy PE individuals. CONCLUSIONS: Clinicians should be aware that in PE individuals, TTE and STE results may not always be indicative of intrinsic myocardial dysfunction, but may be, at least in part, influenced by artifactual and/or external chest shape determinants.

Pectus Arcuatum: A Pectus Unlike Any Other.

BACKGROUND: Pectus arcuatum is often mistaken for a type of pectus carinatum. However, pectus arcuatum is a unique clinical form of pectus caused by premature obliteration of the sternal sutures (manubrial sternum, four sternebrae and xiphoïd process), whereas pectus carinatum is due to abnormal growth of the costal cartilage. In order to better describe pectus arcuatum, we analysed the files of patients with pectus arcuatum followed in our centers. METHODS: Multicenter retrospective study of young patients' files diagnosed with pectus arcuatum. RESULTS: The clinical diagnosis of pectus arcuatum was made in 34 patients with a mean age at diagnosis of 10.3 years (4-23 years). A chest profile X-ray or a CT scan was performed in 16 patients (47%) and confirmed the diagnosis of PA by the presence of a sternal fusion. It was complete in 12 patients. A malformation was associated in 35% of cases (Noonan syndrome 33%, scoliosis 25% or cardiopathy 16%). 11 patients (32%) had a family history of skeletal malformation. Orthopedic treatment was initiated in 3 patients without any success. 11 patients underwent surgical correction, which was completed in 7 of them. CONCLUSION: The diagnosis of pectus arcuatum is based on clinical experience and if necessary, on a profile chest X-ray showing the fusion of the sternal pieces. It implies the search for any associated malformations (musculoskeletal, cardiac, syndromic). Bracing treatment is useless for pectus arcuatum. Corrective surgery, based on a sternotomy associated with a partial chondro-costal resection, can be performed at the end of growth. LEVEL OF EVIDENCE: IV.

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.

Combined Repair of Upper Sternal Cleft and Pectus Excavatum in a Child.

Sternal cleft accompanied by pectus excavatum is a rare type of congenital anomaly of the chest wall. Surgical correction is a suitable approach to restore the heart, large vessels, and respiratory dynamics early. This is a report of the successful surgical correction of upper sternal cleft anomaly accompanied by pectus excavatum in a child. The pectus excavatum was corrected without the use of any prosthesis. The cleft was closed by primary approximation with enough dissected pectoralis major muscle and partial thymectomy, mobility, and flexibility ensured by pectus correction. The integrity of the sternum and the chest wall was normal at the end of the 12-month follow-up period.

Novel index to estimate the cephalocaudal extent of the excavation in pectus excavatum: The Titanic index.

BACKGROUND/PURPOSE: Quantification of the severity of pectus excavatum deformities is currently performed using the Haller index (HI) and the Correction index (CI), amongst others. However, most indexes characterize the severity at the point of maximum excavation. We present a new index, the Titanic index (TI), aimed at the appraisal of the cephalocaudal extent of the excavation and its potential clinical use. MATERIALS AND METHODS: Retrospective analysis of a cohort of patients who underwent a minimally invasive repair of pectus excavatum (MIRPE) between July 2020 and April 2022 at a single center. We defined TI as the percentage of the sternum that lied behind the anterior costal line observed in the CT. Demographics, HI, CI, and TI calculated based on computed tomography images (CT) were analyzed. Also, we compared the severity indexes of two groups of patients divided by the number of implants introduced per patient (group A: two implants, and group B: more than two). RESULTS: Seventy-eight patients (92% male) were included, with a mean age of 17.2 ± 4.8 years. The mean TI was 37%. Albeit weak, we identified significant correlations between the TI and the HI and, more closely, to the CI. Two implants were introduced in 37 (47%) patients, and more than two in 41 (53%) patients. Compared to patients with two implants, the group of patients who received more than two implants were older and showed worse thoracic indexes. Using receiver operating characteristic curve analysis, we identified the TI as a better predictor of the need for more than two implants than HI and CI. In this regard, a TI larger than 66.5% had a sensitivity of 93% and a specificity of 92%. CONCLUSION: We propose a novel index for the categorization of the severity of pectus excavatum. This index might be useful in planning the number of implants required for complete thoracic remodeling during MIRPE. LEVEL OF EVIDENCE: Level III. TYPE OF STUDY: Retrospective Comparative Study.

Associated risk factors for patients undergoing a unique or double Nuss bar placement for pectus excavatum.

BACKGROUND: Pectus excavatum is the most common chest wall deformity. Surgical correction via Nuss Procedure is a common approach. Patients with long-segment sternal depression require more than one Nuss bar to be inserted. Complications of Nuss procedure include surgical site infection and bar migration which may necessitate surgical re-intervention. There has been conflicting evidence regarding the safety profile of inserting two Nuss bars. We aim to specifically review the safety profile of two Nuss bar insertion and its complications. METHOD: 179 consecutive patients who had undergone Nuss procedure between November 2013 and November 2021 were identified. Data analysis was performed on patient's age at time of operation, gender, height, weight, Haller index, pre-existing medical conditions, indication for surgery, duration of operation, numbers of bars placed, length of stay, post-operative pneumothorax, bar migration, superficial and deep infections, need for surgical intervention and mortality. RESULT: Patients receiving two Nuss bars were at a significantly higher risk of developing infective complications. Lower weight and Haller index increase the risk of surgical site infection and infection requiring re-operation in this group of patients. A cut-off of 50 kg has a specificity of 92.1% with a sensitivity of 68.8% in regards to surgical site infection. CONCLUSION: Patients receiving two Nuss bars as a part of their Nuss procedure are at a significantly higher risk of developing infective complications. Selecting patients more than 50 kg to receive two Nuss bars appear to be a reasonable measure to reduce surgical site infection.

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.

Mammographic positioning in women with pectus excavatum: An anatomic challenge.

PURPOSE: To assess mammographic image quality in women with pectus excavatum (PEx) compared to women without PEx. MATERIALS & METHODS: Fifty-six women with PEx between the ages 36-80 (median, 57 years) with screening mammograms from 2006 to 2020 were identified in an IRB-approved HIPAA-compliant retrospective review. Two fellowship-trained breast radiologists independently evaluated mammographic quality of 109 individual breasts in the 56 women using Enhancing Quality Using the Inspection Program (EQUIP) positioning criteria and visual breast density assessments. The number of images per breast was documented. Comparison was made to 2:1 age-matched controls whose screening mammograms were performed in the same year. A power analysis for the difference in the number of images per breast between study groups was performed before data collection. RESULTS: Statistically significant differences with worse performance in women with PEx included: the pectoralis muscle extending to the posterior nipple line (p < 0.0001); adequacy of tissue visualized (p < 0.0001); inframammary fold included (p < 0.0001); breast free of skin folds (p = 0.003); presence of fibroglandular tissue at the CC view posterior edge (p < 0.0001); and CC and MLO within 1 cm of each other (p < 0.001). The average number of images per breast in the PEx group was greater than the control group (2.94 vs. 2.24, p < 0.0001). CONCLUSION: PEx women more often fail to meet mammographic positioning quality standards and more often require additional views for screening.

Pushing the boundaries of minimally invasive repair of pectus excavatum: first experience with a 4-bar technique.

Several modifications to minimally invasive repair of pectus excavatum have been reported to date. Of these, the use of multiple bars was a major development. At present, there are 2 established techniques: cross-bar and parallel bar placement. We used a combination of both parallel and cross-bar techniques in a 25-year-old male patient with deep, Grand-Canyon type pectus excavatum, placing a total of 4 bars and 4 stabilizers. The patient had no complications during the 7 months of postoperative follow-up. We share this case report as the first experience using this modified technique in the literature.