Emergent Surgical Replacement of a Tendyne Prosthesis for Bioprosthetic Valve Thrombosis.

A 66-year-old woman with a complex medical history underwent transcatheter mitral valve replacement (TMVI) owing to mitral insufficiency. Risk factors and noncompliance led to bioprosthetic valve thrombosis (BPVT) within 3 years. Emergent surgery indicated by an ad hoc heart team successfully managed the situation, showcasing challenges in BPVT management after TMVI.

The Effect of Obesity on Short- and Long-Term Outcome after Surgical Treatment for Acute Type A Aortic Dissection.

BACKGROUND: A paradox of lower morbidity and mortality in overweight or obese patients undergoing cardiac surgery has been described; however, knowledge about the influence of obesity in patients with acute Type A aortic dissection (AAD) is limited. This study aimed to evaluate the effect of obesity on short- and long-term outcomes after surgical treatment for AAD. METHODS: Between 01/2004 and 12/2022, 912 patients with a BMI of 18.5 or greater were operated on for AAD. Patients were grouped according to their BMI (normal weight: BMI 18.5-24.9, n = 332; overweight: BMI 25-29.9, n = 367; obesity class I: BMI 30-34.9, n = 133; obesity class II+: BMI ≥ 35, n = 67), and the obtained clinical and surgical data were compared. RESULTS: Obese patients were younger at the time of AAD (p = 0.001) and demonstrated higher rates of typical cardiovascular comorbidities (arterial hypertension, p = 0.005; diabetes mellitus, p < 0.001). The most important preoperative parameters, as well as the surgical approach, were similar between all four groups. The occurrence of renal failure requiring dialysis was higher in patients with BMI ≥ 35 (p = 0.010), but the in-hospital (p = 0.461) and long-term survival (p = 0.894) showed no significant differences. CONCLUSIONS: There are no indications that the obesity paradox is applicable in the setting of AAD. Since obese patients are affected by AAD at a younger age, obesity might constitute a risk factor for AAD. However, obesity does not influence short- or long-term survival. Regardless of body weight, immediate surgical therapy remains the treatment of choice for AAD.

A Rare Association of Autoimmune Hypophysitis With Seronegative Rheumatoid Arthritis: A Case Report.

Autoimmune hypophysitis (AH) is an uncommon condition where there is inflammation of the pituitary gland which leads to hormonal imbalances. It is often associated with autoimmune diseases; however, a case is yet to be reported with an association of AH with seronegative rheumatoid arthritis (RA). We present a case of a 45-year-old female who complained of polyuria/polydipsia and rapid weight gain. An MRI of the head revealed enlargement of the pituitary gland, concerning for AH. Although she was initially treated for diabetes insipidus, she began reporting new complaints of joint pains and morning stiffness. She was clinically diagnosed with seronegative RA and improved with a trial of hydroxychloroquine. A repeat MRI showed improvement in the abnormal pituitary findings, and the patient was closely monitored with a multidisciplinary approach. Diagnosing and managing patients with AH are topics that are still being explored and researched as it is a relatively rare pathology. Consequently, we found the need to discuss the relationship of AH with seronegative RA and delve into the various diagnostic and treatment approaches.

Sex Differences in Short- and Long-Term Survival after Acute Type A Aortic Dissection.

Background and Objectives: Acute type A aortic dissection (AAD) is a life-threatening disease. No differences between men and women have been made in the treatment of AAD so far and knowledge about sex differences regarding long-term outcomes is limited. Materials and Methods: Between 01/2004 and 12/2021, 874 patients were operated on for AAD, including 313 (35.8%) women and 561 (64.2%) men. Clinical and surgical records, including long-term follow-up information, were obtained and analyzed retrospectively. To account for differences in the outcome determined by different preoperative life expectancies, a subgroup analysis for a set of patients matched according to their remaining life expectancy was performed. Results: At the time of AAD, women were older than men (69.1 ± 13.0 vs. 61.8 ± 13.3 years, p < 0.001) and had a shorter remaining statistical life expectancy (18.6 ± 10.8 vs. 21.4 ± 10.4 years, p < 0.001). Significantly more DeBakey type II AAD was found in women (37.1% vs. 25.7%, p < 0.001). Comorbidities and preoperative status at the time of presentation were similar in women and men. More hemiarch procedures (63.3% vs. 52.0%, p < 0.001) and less arch replacements (8.6% vs. 16.6%, p < 0.001) were performed in women, resulting in shorter cross-clamp times for women (92 ± 39 vs. 102 ± 49 min, p < 0.001). The in-hospital mortality was similar in women and men (11.5% vs. 12.7%, p = 0.618). Long-term survival was significantly shorter in women compared to men (9.8 [8.1-11.5] vs. 15.1 [11.9-18.4] years, p = 0.011). A matched subgroup analysis revealed that when comparing groups with a similar remaining life expectancy, the long-term survival showed no significant differences between women and men (9.8 [7.9-11.6] vs. 12.4 [10.1-14.7] years, p = 0.487). Conclusions: There are sex differences in AAD, with DeBakey type II dissection being more frequent in women. The seemingly worse long-term outcome can mostly be attributed to the shorter remaining statistical life expectancy at the time of presentation.

Understanding tumor localization in multiparametric MRI of the prostate-effectiveness of 3D printed models.

Introduction: Understanding tumor localization in multiparametric MRI (mpMRI) of the prostate is challenging for urologists but of great importance in mpMRI-fused prostate biopsy or radical prostatectomy. The aim was to evaluate the effectiveness of 3D printed models of the prostate to help urologists to locate tumors. Methods and Participants: 20 urologists from University Medical Center Mainz (Germany) were asked to plot the location of a cancer suspicious lesion (PI-RADS ≥ 4) on a total of 30 mpMRI on a prostate sector diagram. The following 3 groups (as matched triplets) were divided into: mpMRI only, mpMRI with radiological report and mpMRI with 3D printed model (scaled 1:1). Statistical analysis was performed using one-way and two-way ANOVA (with bonferroni post-test). Results: Overall, localization of the suspicious lesion was superior with the radiological report (median of max. 10 [IQR]: MRI 2 [IQR 1;5], MRI + report: 8 [6.3;9], MRI + 3D model 3 [1.3;5.8]; p < 0.001). Residents with <1 year of experience had a significantly higher detection rate using a 3D printed model [5 (5;5.8)] compared to mpMRI alone [1.5 (1;3.5)] (p < 0.05). Regarding the estimation of index lesion extension, the 3D model showed a significant benefit (mean percentage difference [95% CI]: MRI alone 234% [17.1;451.5], MRI + report 114% [78.5;149.6], MRI + 3D model 17% [-7.4;41.3] (p < 0.01). Conclusion: Urologists still need the written radiological report for a sufficient understanding of tumor localization. The effectiveness of the 3D printed model regarding tumor localization is particularly evident in young residents (<1 year) and leads to a better overall assessment of the tumor extension.

Synthesis, electrospinning, and molecular docking of poly(methyl methacrylate) Schiff bases and their applications as polymeric antimicrobial agents and for dye removal.

The antibacterial activity of a variety of modified poly(methyl methacrylate) Schiff bases against common microbial infections and removal of methylene blue (MB) dye were screened. The Schiff bases were synthesized from the reaction of the modified (PMMA) with vanillin (PMMA)Van and cinnamaldehyde (PMMA)Cin. By using Fourier transformer infrared (FT-IR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), the structures of the nanofibers of the synthesized Schiff bases were confirmed. The modified Kirky-Bauer method was used to screen the antibacterial activities of all the obtained materials against various bacterial species, including gram-positive bacterial (Bacillus subtilis (4k1p), Staphylococcus aureus), Gram-negative bacteria (Escherichia coli (7ab3), Pseudomonas aeruginosa). Inhibition zones against gram-positive bacteria ranged in diameter from 7 to 14 mm, whereas for the Gram-negative bacteria, the inhibition zones found to be ranged between 6 and 13 mm. With a minimum bactericidal concentration (MBC) of 8 mg/mL and a minimum inhibitory concentration (MIC) of 2 mg/mL, (PMMA)Van shown the greatest antibacterial activity. Lastly, molecular docking research was done to better understand the interactions between this series' targets and inhibitors for (PMMA)Van and (PMMA)Cin (4k1p and 7ab3). Molecular modeling of these surface-adsorbed polymers indicated that (PMMA)Van binds more strongly with Nitrogen than does (PMMA)Cin through extra hydrogen-bonding interactions. All the developed materials were evaluated for the removal of 0.1 g/L methylene blue dye (MB) from an aqueous solution. The elimination percentage of MB dye ranged from 26.67% by using 0.05 g powder of (PMMA)Cin to 85.63% by employing 0.05 g nanofibers of (PMMA)Van.

Synthesis, Characterization, and Anticancer Potency of Branched Poly (p-Hydroxy Styrene) Schiff-Bases.

A significant issue in cancer biology is finding anticancer therapies that effectively kill cancer cells. Through the use of several aldehydes, Schiff bases based on branched poly (p-hydroxy styrene) are created. The branched polymer is first chloroacetylated, then aminated with 1,4-phenylenediamine, and finally, aldehydes are reacted with the aminated polymer to produce the Schiff base compounds. Through the utilization of FTIR, TGA, XRD, NMR, and elemental analysis, all synthesized Schiff-bases are identified and characterized. Further, the antineoplastic potential of all Schiff bases is evaluated against different cancer cell lines. The results gained from this study indicate that the Schiff base polymers have cytotoxic power against cancer cells depending on cancer cell type and this antiproliferation potency is dose-concentration dependent. Importantly, the prepared S1 Schiff-base polymer shows potent cytotoxicity and is able to trigger the apoptosis and reactive oxygen species (ROS) in MCF-7 cells. Further, it downregulates VEGFR protein expression. The Schiff base polymers would have extensive applications in the biological disciplines.

Island remodelling in acute and chronic aortic dissection treated with frozen elephant trunk.

OBJECTIVES: The island technique for reimplantation of supra-aortic vessels in frozen elephant surgery is commonly used but might be questioned for dissected vessels. This study analyses the remodelling of reimplanted supra-aortic vessels after FET in acute and chronic aortic dissection (CAD). METHODS: Between June 2017 and April 2021, 133 patients were operated for acute and CAD using the frozen elephant technique. The island technique for reimplantation of the supra-aortic vessels was used in 94/133 patients. In 68 acute and 21 chronic patients, the total vessel lumen (VL), true lumen, false lumen (FL) and perfused FL area were measured in the innominate, right common carotid and left common carotid artery. Relative luminal changes were compared. RESULTS: In acute aortic dissection, 80% innominate, 40% right carotid and 59% left carotid arteries were dissected preoperatively, but postoperatively FL was only patent in 29%, 12% and 10% (P < 0.001). FL disappearance resulted in >20% total VL reduction in innominate, right carotid and left carotid artery (P < 0.01). In CAD, only 38% innominate, 14% right carotid and 43% left carotid arteries were dissected preoperatively, but postoperatively FL was patent in 19% (ns), 10% (ns) and 5% (P = 0.009). CONCLUSION: Vascular remodelling is frequently found after the island technique. In acute aortic dissection, the island technique frequently initiates FL disappearance associated with VL decrease. Continuously dissected head vessels show positive remodelling with true lumen increase without VL increase. FL disappearance is frequently found in CAD.

Perioperative Safety of Bilateral Internal Thoracic Artery Coronary Bypass in Elderly.

Background: The benefits of utilizing internal thoracic arteries (ITAs) in coronary bypass surgery are well-known. However, the safety of this practice in elderly patients needs to be proven. Methods: We studied all patients who are 75 years of age and older, who received at least one ITA graft while undergoing isolated, conventional (median sternotomy) coronary artery bypass graft surgery (CABG) between Jan 1st 2002 and Dec 31st 2020 (19 years). Emergent surgeries were excluded. Propensity score matching was used to reduce the patient selection effect. Study outcomes were 30-days mortality, and two sets of dependent intraoperative parameters and postoperative parameters. Results: A total of 1855 patients undergoing CABG was included, of which 1114 received a single left (s)ITA and 741 received combined left and right (d)ITA grafts. 519 pairs were matched. The decision for sITA or dITA was made individually. Thirty-days mortality was low and similar in both groups (sITA 3.3%; dITA 2.9%, p = 0.859). The incidence of sternal wound healing disorder was higher after dITA (3.3 vs 6.9%; p < 0.011), which had also a longer skin-to-skin operative time (181 vs 205 min; p < 0.0001). Re-thoracotomy rates were similar (4.6 vs 6.2%; p = 0.340). There were no significant differences in other secondary parameters. Conclusions: harvesting both ITAs in elderly patients is safe and feasible. However, it increases the risk of sternal wound healing disorders. Long term benefit still needs to be proven.

Does Mental Distress Predict Cardiac Surgical Outcome?

BACKGROUND: Mental distress is suspected to influence the morbidity of cardiac patients. Evaluating mental distress in cardiac patients is rare and the impact on surgical outcome is still not certified. METHODS: In 94 cardiac surgical patients, mental distress was assessed by the Patient Health Questionnaire-4 (PHQ-4). We defined length of stay in hospital and on intensive care unit as well as time of mechanical ventilation as outcomes on surgery. Age, physical activity, diabetes, overweight, PHQ-4, and an inflammation marker were tested for their predictive value on outcomes. RESULTS: Reportedly prevalence of generalized anxiety was 16.0% and depression rate was 13.8%. Length of stay in hospital was 13 ± 8 days, time of mechanical ventilation was 10 (0-1,207) hours, and length of stay on intensive care unit was 3 ± 6 days. Length of stay in hospital was significantly predicted by age (p = 0.048), low physical activity (p = 0.029), and high C-reactive protein (CRP; p = 0.031). Furthermore, CRP was the only significant predictor of time of mechanical ventilation and length of stay on intensive care unit. CONCLUSION: Outcome was not predicted by mental distress. However, inflammation marker CRP was predictive for outcome, potentially caused by higher cardiovascular risk profile. Additionally, depression was referred to be associated with inflammation. Probably, the small sample and the timing of assessment were responsible for the missing relation between mental distress and outcome. We presume a relation with low physical activity and depression. Nevertheless, further randomized studies are needed to pay more attention on patients' distress to intervene preoperatively to improve postoperative outcome.

Training Cardiac Surgeons: Safety and Requirements.

To analyze whether cardiac surgical residents can perform their first surgeries without compromising patients' safety or outcomes, by comparing their performance and results to those of senior surgeons. All documented CABGs conducted between 2002 and 2020 were included. Surgeries were divided according to the experience level of the main surgeon (defined by the number of CABG conducted by him/her) using the following thresholds: 1000; 150; 80 and 35. This resulted in 5 groups: senior surgeons (the reference group); attending surgeons; fellow surgeons; advanced residents and new residents. Primary endpoint was 30 day mortality. Secondary endpoints included a list of intra and post-operative parameters (including in-hospital complications). A multivariable analysis was conducted. 16,486 CABG were conducted by 66 different surgeons over a period of 18 years. Multivariable analysis did not find significant differences between both the primary and the secondary endpoints. Skin-to-skin time correlated significantly with experience level, as new residents needed almost 30% more time than senior surgeons (234 vs 180 minutes). With a suitable supervision by experienced surgeons, patient selection and sufficient resources (longer duration of surgery), surgical residents can perform CABGs with good results and without compromising the patient's outcome.

Association of vitamin B12 deficiency with metformin use in patients with type 2 diabetes treated in the largest tertiary care hospital in Qatar.

BACKGROUND: Data on the effect of metformin on serum vitamin B12 (VitB12) level in patients with type 2 diabetes mellitus (T2DM) in Qatar are limited; therefore, we aimed to assess the prevalence of VitB12 deficiency and its related factors among patients with tbl2DM treated with metformin at Hamad General Hospital in Doha, Qatar, from January 1, 2017, to December 31, 2017. METHODS: This cross-sectional analytical study involved patients with tbl2DM aged ≥ 18 years who used metformin for at least 3 months. The serum VitB12 was quantified on a chemiluminescent enzyme immunoassay analyzer using Cobas e 801 module, Roche, and VitB12 deficiency was defined as serum VitB12 level of ≤ 145 pmol/L. All data were obtained from the patients' electronic medical records. RESULTS: The study recruited 3124 eligible patients with tbl2DM. The overall prevalence of metformin-associated VitB12 deficiency was 30.7% [95% confidence of interval, 0.290-0.323]. A significant difference exists in the median VitB12 levels between the VitB12-normal and VitB12-deficient groups [129 vs. 286; p < 0.001]. Compared with the VitB12-normal group, the VitB12-deficient group had higher mean body mass index (BMI) (p < 0.001) and consumed higher doses of metformin (p = 0.001). They also more often used sulfonylurea (p = 0.004), dipeptidyl peptidase-4 inhibitor (p < 0.001), thiazolidinediones (p < 0.001), glucagon-like peptide 1 [GLP-1] receptor agonists (p < 0.001), alpha-glucosidase inhibitor (p < 0.001), and H2 blocker/proton pump inhibitors [PPI] (p < 0.001) than the VitB12-normal group. Moreover, the VitB12-normal group consumed more calcium supplements (p < 0.001) than the VitB12-deficient group. In the multivariate analysis, independent risk factors for metformin-associated VitB12 deficiency in patients with tbl2DM include high daily dose of metformin >2000 mg, male gender, high BMI, smoking, sulfonylurea, dipeptidyl peptidase-4 inhibitor, H2 blockers/PPI, low fasting blood glucose, and low hemoglobin. CONCLUSION: This study showed a high prevalence of VitB12 deficiency in patients with tbl2DM taking metformin and a significant negative correlation between the daily dose of metformin and serum VitB12 level. Therefore, regular screening for serum VitB12 is necessary in patients with tbl2DM on metformin treatment, especially those who have the abovementioned risk factors.

Negative effect of high-level infrasound on human myocardial contractility: In-vitro controlled experiment.

BACKGROUND: Human exposure to infrasound is increasing due to man-made factors, such as occupational conditions, wind farms and transportation. The concern among the public regarding the safety of infrasound exposure is growing. AIMS: To evaluate whether exposure to infrasound interferes directly with human cardiac function and contributes to pathological processes. SETTING: The University Hospital of Mainz, Germany. METHODS: Human myocardial tissues, obtained from patients undergoing cardiac surgery, were prepared in small muscle samples and stimulated electrically in-vitro for a period of almost two hours under physiological conditions to induce continuous pulsatile contractions and simulating a working human heart. Two samples were obtained from each donor: one was subjected to infrasound for 60 min and the other served as a control. Their contraction forces (CF) and durations (CD) were measured before and after each testing period and their relative changes (CF% and CD%) were calculated and introduced in a multilinear regression model. The following three infrasound levels of exposure were used in this study: 100, 110 and 120 dBz. RESULTS: The measured CF% corresponded negatively with the infrasound level measured in dBz (R2 = 0.631; P = 0.018). The decrease measured almost -11% at 110 dBz and -18% at 120 dBz, after correction for control. The CD on the other hand remained unchanged. CONCLUSIONS: Exposure to high levels of infrasound (more than 100 dBz) interferes with cardiac muscle contractile ability, as early as one hour after exposure. There are numerous additional studies which support this conclusion. These results should be taken into account when considering environmental regulations.

Minimally invasive coronary artery bypass grafting via a lower ministernotomy for left anterior descending artery myocardial bridging: mid-term results.

OBJECTIVES: Coronary artery bypass grafting or supra-arterial myotomy is now suggested as a better therapeutic option in myocardial bridging (MB) when medical treatment fails to control symptoms. For left anterior descending (LAD) MB, minimally invasive coronary artery bypass via a lower ministernotomy can be offered. METHODS: Forty-four consecutive patients who underwent elective minimally invasive coronary artery bypass surgery from 2005 to 2014 via an inferior sternotomy using the left internal mammary artery as a bypass graft for LAD MB were evaluated retrospectively. RESULTS: The mean age was 59.1 ± 13.1 years with 26 (59%) men and 18 (41%) women. The mean body mass index was 27.2 ± 3.9 and the mean EuroSCORE II was 1.6 ± 1.8. Routine coronary multislice computed tomography angiography on the 6th postoperative day revealed 97.7% graft patency. During the initial hospital stay, 1 patient (2.3%) underwent a reoperation for early graft failure. Forty patients (91%) could be followed up for a mean period of 64.4 ± 24.5 months after the procedure, during which 2 patients (4.5%) died of non-cardiac causes and 9 patients (20.5%) underwent postoperative coronary angiography with confirmed graft occlusion in only 1 case (2.3%). The improvement in the distribution of patients in the Canadian Cardiovascular Society class 0 was from 4 patients (9%) preoperatively to 37 patients (84%) at the end of the follow-up period (P-value 0.001). CONCLUSIONS: Minimally invasive coronary artery bypass surgery via a lower ministernotomy may be safe and efficient for treating LAD artery MB with acceptable complication rates, cosmetic benefits and patency rates.

Body Mass Index (BMI) and Its Influence on the Cardiovascular and Operative Risk Profile in Coronary Artery Bypass Grafting Patients: Impact of Inflammation and Leptin.

BACKGROUND: Obesity is related to coronary artery disease (CAD) and worse outcomes in coronary artery bypass graft (CABG) patients. Adipose tissue itself is an endocrine organ that secretes many humoral mediators, such as adipokines, which can induce or reduce inflammation and oxidative stress. OBJECTIVES: We investigate the relationship between the body mass index (BMI), inflammation, and oxidative stress by measuring serum levels of leptin, interleukin-6, and 3-nitrotyrosine in CABG patients and correlate their levels to the cardiovascular and operative risk profiles. METHODS AND RESULTS: 45 men (<75 years) with a median BMI of 29 (21-51) kg/m2, who were diagnosed with CAD and scheduled for elective CABG, were included after applying the following exclusion criteria: prior myocardial infarction, reoperation, female gender, and smoking. Patients' blood samples were taken preoperatively. Several markers were measured. We found significant correlations between leptin and BMI (p < 0.0001) as well as between leptin and 3-nitrotyrosine (p = 0.006). Interleukin-6 was correlated with C-reactive protein (p < 0.0001) and with the incidence of insulin-dependent diabetes mellitus (p = 0.036), arterial hypertension (p = 0.044), reduced left ventricular function (p = 0.003), and severe coronary calcification (p = 0.015). It was also associated with significantly longer extracorporeal bypass time (p = 0.009). Postoperative deep sternal wound infections could be predicted by a higher BMI (p = 0.003) and leptin level (p = 0.001). CONCLUSIONS: There seems to be a correlation between inflammatory processes and cardiovascular morbidity in our cohort. Further, the incidence of deep sternal wound infections is related to a higher BMI and leptin serum level.

Leveraging spatial uncertainty for online error compensation in EMT.

PURPOSE: Electromagnetic tracking (EMT) can potentially complement fluoroscopic navigation, reducing radiation exposure in a hybrid setting. Due to the susceptibility to external distortions, systematic error in EMT needs to be compensated algorithmically. Compensation algorithms for EMT in guidewire procedures are only practical in an online setting. METHODS: We collect positional data and train a symmetric artificial neural network (ANN) architecture for compensating navigation error. The results are evaluated in both online and offline scenarios and are compared to polynomial fits. We assess spatial uncertainty of the compensation proposed by the ANN. Simulations based on real data show how this uncertainty measure can be utilized to improve accuracy and limit radiation exposure in hybrid navigation. RESULTS: ANNs compensate unseen distortions by more than 70%, outperforming polynomial regression. Working on known distortions, ANNs outperform polynomials as well. We empirically demonstrate a linear relationship between tracking accuracy and model uncertainty. The effectiveness of hybrid tracking is shown in a simulation experiment. CONCLUSION: ANNs are suitable for EMT error compensation and can generalize across unseen distortions. Model uncertainty needs to be assessed when spatial error compensation algorithms are developed, so that training data collection can be optimized. Finally, we find that error compensation in EMT reduces the need for X-ray images in hybrid navigation.

[The Future of Vascular Medicine - Role of 3D Printing]. / Gefäßmedizin in der Zukunft ­ Möglichkeiten mit 3D-Druckverfahren.

Digitalisation is one of the key challenges in current surgery and will impact the future of surgical care as well as upcoming generations of surgeons. 3D printing is a technology that has recently been transferred from industrial prototyping into cardiovascular medicine. The digital model of the anatomical structure which needs to be engineered represents the inherent link of 3D printing to digital medicine. 3D printing technology is able to provide the surgeon with patient-specific models of anatomy and disease for surgical planning and patient informed consent as well as training templates for students and residents, surgical templates and even ready-to-use surgical implants. In our service, we have established a full-inhouse workflow for 3D printing and we currently use this technology for the generation of patient-specific models, training templates and for patient education, as will be presented in this article. Future advances in software solutions, printing polymers and easy-to-handle printers will further propagate and expand the applicability of this technology in cardiovascular medicine.

Development and evaluation of 3-dimensional printed models of the human tracheobronchial system for training in flexible bronchoscopy.

OBJECTIVES: Training and assessment of proper skills in flexible bronchoscopy are major educational goals for cardiothoracic residents. Therefore, we developed 3-dimensional (3D) printed models of the human tracheobronchial system for training and assessment of cardiothoracic residents in flexible bronchoscopy. METHODS: Three models of normal (size/shape) human tracheobronchial anatomy were generated using a commercially available 3D printer. Ten residents (inexperienced: Group 1; experienced: Group 2) participated in this study with an experimental setting of initial assessment (Model 1), training (15 min, Model 2) and post-training assessment (Model 3). The time needed for flexible bronchoscopy assessment of randomly assigned ostia was recorded before and after training. Additionally, the time for retrieval of a foreign body from the tracheobronchial system was measured before and after training. RESULTS: The average time for intubation of a given ostium (Model 1) at initial assessment was 88 s for Group 1 and 38 s for Group 2 (P < 0.0001). Following training, there was a significant reduction in time for intubation of a given ostium (Model 3) in both groups (P < 0.0001). However, the initial difference between experienced and inexperienced residents was no longer present following training. Additionally, the time for retrieval of a foreign body (cotton wool plug) from the tracheobronchial system was significantly reduced following training in both groups. CONCLUSIONS: Accurate models of the human tracheobronchial system can be generated from representative patient images using 3D engineering software and 3D printing technology. With these models, residents can be effectively trained in flexible bronchoscopy with significant improvement in their proficiency and handling capability.

Applications of patient-specific 3D printing in medicine.

Already three decades ago, the potential of medical 3D printing (3DP) or rapid prototyping for improved patient treatment began to be recognized. Since then, more and more medical indications in different surgical disciplines have been improved by using this new technique. Numerous examples have demonstrated the enormous benefit of 3DP in the medical care of patients by, for example, planning complex surgical interventions preoperatively, reducing implantation steps and anesthesia times, and helping with intraoperative orientation. At the beginning of every individual 3D model, patient-specific data on the basis of computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound data is generated, which is then digitalized and processed using computer-aided design/computer-aided manufacturing (CAD/CAM) software. Finally, the resulting data sets are used to generate 3D-printed models or even implants. There are a variety of different application areas in the various medical fields, eg, drill or positioning templates, or surgical guides in maxillofacial surgery, or patient-specific implants in orthopedics. Furthermore, in vascular surgery it is possible to visualize pathologies such as aortic aneurysms so as to improve the planning of surgical treatment. Although rapid prototyping of individual models and implants is already applied very successfully in regenerative medicine, most of the materials used for 3DP are not yet suitable for implantation in the body. Therefore, it will be necessary in future to develop novel therapy approaches and design new materials in order to completely reconstruct natural tissue.