An Innovative Stereolithography 3D Tubular Method for Ultrathin Polymeric Stent Manufacture: The Effect of Process Parameters

In the last decades, researchers have been developing bioresorbable stents (BRS) to overcome the long-term complications of drug-eluting stents (DES). However, BRS technology still presents challenging limitations in terms of manufacturing, materials, or mechanical properties. At this juncture, companies have developed ultrathin DES that may further improve the efficacy and safety profile of traditional DES by reducing the risk of target-lesion and target-vessel failures until BRS are developed. Nonetheless, the metallic platform of ultrathin DES still presents problems related to their cellular response. The use of polymers as a permanent platform in DES has not previously been studied due to the limitations of current manufacturing technologies. In this work, an innovative manufacturing method for polymeric stent production using tubular stereolithography (SLA) technology is proposed both for BRS and for ultrathin polymeric DES. The effects of manufacturing process parameters were studied by modelling the outcomes (stent thickness and strut width) with the key manufacturing variables (exposure, resin volume, and number of layers). Two different laser setups were used to compare the results. Microscopy results proved the merit of this novel tubular SLA process, which was able to obtain stents with 70 μm strut width and thickness in barely 4 min using only 0.2 mL of resin. Differential Scanning Calorimetry (DSC) results showed the stability of the manufacturing method. The results obtained with this innovative technology are promising and overcome the limitations of other previously used and available technologies.

Bicuspid aortic valve: prompt identification of high-risk groups in a heterogeneous disease

Background

Bicuspid aortic valve (BAV) is a congenital heart disease that can be associated with aortic and/or valve complications. Although most BAV are predisposed to progressive calcification, little is known on variables related to significant valvular dysfunction. BAV is a heterogeneous disease, therefore it is important to identify high-risk groups for a closer follow- up and timely intervention.

Objective

Identify the main determinants of primary cardiovascular events (aortic valve replacement, aortic surgery and death) in a cohort of adults with BAV.

Methods

We included 325 consecutive patients with non-syndromatic BAV (2010–2019) referred to our hospital (3rd level). Clinical information was prospectively collected. All patients underwent serial echocardiograms and Cardiac CT was available in 125 patients (38%). We performed univariate and multivariate analyses and Kaplan-Meyer survival analysis with log-rank test. A p-value <0.05 was considered significant.

Results

325 patients (44.4±15.3 years, 73% men), right–left coronary cusp fusion (RL) in 79%,and presence of raphe in 77%. 100 patients (31.2%) had significant aortic valve dysfunction and 103 (31.7%) had aortic dialatation (>40mm) at the onset of the follow-up. Twenty-nine patients required cardiac surgery (8.9%, mainly symptomatic severe aortic stenosis with aortic valve replacement)and 3 died (1%) during a follow-up of 6.3±1.2 years. Patients with at least 2 of the following determinants at baseline: aortic valve prolapse, aortic valve calcification >1, age >50 years and/or aorta >45mm had higher risk of major cardiovascular events during follow-up (Chi2 for log rank test=27,229 p=0,000005).

Conclusions

In this study population of young adults with BAV we observed a high incidence of events related to the BAV. Age>50 years, aortic valve calcification, aortic valve prolapse and aortic dilatation were independently associated with primary cardiac events. Despite significant BAV heterogeneity, the identification of risk factors may help to stratify the risk of valvular dysfunction, aortic dilatation and major cardiovascular events.

BAV: Risk factors for cardiac surgery

Funding Acknowledgement

Type of funding source: None

P811 More than aortic measurements: evaluation with TTE and angioCT in bicuspid aortic valve yields useful information about valvular compromise

Background

2D transthoracic echocardiogram (TTE) is the technique of choice in the diagnosis of bicuspid aortic valve (BAV). Computed tomography (CT) is widely used in BAV to measure aortic diameters. However, in some cases CT or magnetic resonance (MRI) can add important information to TTE regarding valvular degeneration and morphotype.

We designed the present prospective study to determine the agreement between TTE and gated CT in the assessment of aortic valve morphology, fibrosis, calcification and measurements of thoracic aorta. We also aimed to analyze the utility of CT in the evaluation of BAV patients, in addition to aortic measurements.

Methods

We included 30 consecutive patients with BAV (mean age 45 ± 15.7 years ; 73.3% men) who underwent both TTE and ECG-gated cardiac and aortic CT for valvular and aortic assessment in a follow-up protocol with a time interval between TTE and CT of 4 ± 2.6 months.

We performed measurements of thoracic aorta at 6 levels (annulus, Valsalva sinus: VS, sinotubular junction, ascendent, arch and isthmus) with both techniques following guideline recommendations blinded to the results of the other technique.

Several measurements of VS were performed in short-axis view (double-oblique method) (maximal diameter perpendicular to the valve opening, sinus to sinus, raphe to sinus, commissure to commissure) at systole and diastole with CT.

Valve phenotype, presence of raphe, calcification scoring, aortic valve prolapse and fibrosis were also determined with both techniques and maximum aortic diameters were compared. An indexed aortic diameter > 21 mm/m2 was considered as aortic dilation and assimetryc root was defined when differences between CT measurements were ≥5mm.

Results

In 7 patients (23.3%) aortic diameter differences at Sinus by TTE and CT were ≥3mm. Concerning ascending aorta measurements, there was better agreement and only 2 cases (6.6%) showed differences ≥ 3mm.

In 2 patients with severe calcification valve morphology was identified only with CT. There was good agreement between TTE and CT in calcium quantification in patients with valvular calcium score over 2000 AU (n = 5) and in those without calcification. However, TTE failed in identification of valvular fibrosis in 5 patients.

10 patients (30%) had aortic dilatation with CT and 7 according to TTE measurements. The 3 patients that were not identified as dilated in TTE had dilatation at the distal tubular portion.

CT led to identification of coronary anomalies in 5 patients (16.7%), most of them anomalous high origin above the sinotubular junction.

Conclusions

Although TTE is the gold-standard in the diagnosis and follow-up of patients with BAV, CT was useful to confirm aortic measurements and to identify valvular fibrosis, assimetry, coronary anomalies and dilatation at the tubular portion. CT can add important information to TTE regarding valvular morphotype and aortic measurements, although radiation and cost should be evaluated.

Abstract P811 Figure. Calcification agreement TTE and CT

P2788First argentine national registry of echocardiograpphic aortic dimensions: body surface area, age and ethnicity are determinants of aortic dimensions

Background

Transthoracic echocardiography (TTE) remains the screening tool of choice for thoracic aorta (TA) dilatation. Differences in TA diameters (TAD) according to gender (G), age (A) and body surface area (BSA) have been previously reported. However, these reports are limited by a small sample size, different measurement sites or heterogeneous cohorts. There is scarce data on the influence of ethnicitiy on TAD. Moreover, surgery indication for TA aneurysms is still based mainly on absolute TAD with no reference to G, A or BSA.

Purpose

We designed a prospective nationwide multicenter registry to determine the normal range of TAD at all TA segments in healthy adults of both G and their correlations with A, ethnicity and BSA.

Methods

Healthy adult individuals without cardiovascular risk factors, TA aneurysm, aortic valve disease, cardiac surgery or genetic aortopathies were recruited from 53 centers in Argentina. TTEs were acquired and measured following standard protocols based on EACVI/ASE Guidelines. TAD were measured at six levels: annulus, sinuses of Valsalva, sinotubular junction, tubular ascending aorta, aortic arch and proximal descending aorta. Annulus was measured at mid-systole (inner to inner edge method) and all other at end-diastole (leading to leading edge).

Multiple linear regression models were conducted to obtain coefficients of determination (R2) and 95% prediction intervals. We defined upper normal limits (95th percentile) for 4 age categories, both G and analyzed differences according to ethnicity.

Results

The MATEAR registry included 905 healthy adult patients (mean age: 38.3±13 years, 508 women, BSA: 1.8±0.2 m2). 529 (58.4%) were caucasian and 332 (36.6%) native-american, representative of the ethnic composition of Argentine population.

Pooled data showed a positive correlation between all TAD and A or BSA (p<0.001), similar in both G. Women had smaller absolute TAD due to their lower BSA. Nomograms were obtained for 4 age categories to predict TAD from BSA with no need of G distinction. Native americans showed significatly lower absolute and indexed TAD than caucasian (p<0.01) from annulus to isthmus.

TAD differences according to ethnicity

Conclusions

While age and BSA were significant determinants of aortic dimensions at six levels, we have also detected differences in TAD according to ethnicity, suggesting normative values should also be defined for each ethnic group. We propose nomograms of indexed TAD for different age and ethnic groups without G distinction.

6124Aorta and sports. the silent threat

Background

Thoracic aorta is the less known component of the athlete's heart and current publications shown that may be larger in athletes. It is known that high static training and body collision sports could increase the risk of sudden death, especially in patients with aortic disease (AD). Large scale traditional screening detects underlying cardiovascular diseases which may cause sudden cardiac death (SCD), however AD might be subdiagnosed.

OBJECTIVE

To describe AD burden on preparticipation screening and to assess diagnostic precision of traditional screening for AD detection in trained athletes.

Methods

Different sports athletes were recruited to follow current European guidelines (clinical history and cardiac examination, including resting 12-lead ECG) for preparticipation screening program (PSP). Bidimensional transthoracic echocardiography (TTE) was performed in all patients to detect AD: bicuspid aortic valve (BAV), thoracic aorta dilatation by Z score (TAD) and BAV plus TAD (BAD). Athletes were excluded from competition following international criteria. Sensitivity (Sn) and specificity (Sp) were calculated with 95% Clopper-Pearson confidence intervals and results are expressed as percentajes. McNemar paired chi-square test for one sample of individuals was used to compare diagnostic precision (Sn, Sp) of PSP vs gold standard: complete assessment (for sport exclusion, SpE) or TTE (for AD or BAD detection). Significance was set at p<0.05

Results

Included population (n=1123) was 22.3±6.2 y-o and 222 (19.8%) female. Five athletes (0.44% of total) were excluded from competition due to different causes. AD was found on 11 athletes (0.98%) and 4 of them had BAD (0.36%), a high risk condition with poor prognosis. Three patients with BAD were competitive cyclists and close follow up was indicated. The remaining patient with BAD was a rugby player and was excluded from competition (one out of 5 excluded patients, 20%). Diagnostic precision of PSP was better for SpE than for AD or BAD diagnosis. PSP tended to have less Sn for AD [36.4 (10.9–69.2)] and BAD [25 (0.6–80.6)] detection, than for SpE [80 (28.4–99.5); p=NS]. PSP had significant less Sp for AD [91.1 (89.3–92.7)] and BAD [90.9 (89–92.5)] diagnosis, than for SpE [97.2 (96.1–98.1); p<0.05].

Conclusions

AD is subdiagnosed by current PSP and its burden may be overlooked. Despite BAD is less frequent, its finding is determinant in a significant proportion of cases to decide exclusion from competitive (high static or body collision) sports. Although PSP has good sensitivity to detect potential pathologies of SCD, AD cannot be ruled out only by normal ECG and clinical examination. Diagnostic precision of PSP for AD and BAD detection could be enhanced by TTE screening, new studies with a larger number of athletes may answer the question.

[The health status and bucco-dental pathology in the elderly]

By analysing in 2,769 patients the relation between bucco-dental pathology and age, it was noticed that the frequency of odontic affections decreases and that of chronic marginal periodontopathies increases with age. In the elderly, a tendency towards delaying the treatment of pulp inflammations and a very high percentage of extractions performed in the chronic marginal periodontopathies (81.8%) were noticed. The bucco-dental state of health was determined in 75 old-aged over 60 years, the ICORA and CPITN indices being used. Of these individuals, 93.3% presented various edentate forms, half without prosthetic appliance. Various degrees of pathological changes in the marginal periodontium were recorded in 92.3%, being more severe in women and individuals from rural areas.

[Aspects of professional hygiene in dental technical laboratories]

Investigations on hygiene and sanitary conditions in a laboratory for dental techniques consisted in physico-chemical determinations on microclimate (temperature, humidity, air currents), determination of dust particles (suspended and sedimented), determination of gases (CO, CO2, NO2, NH3, SO4(2-), chloride ions), and determination of microelements (Fe, Cu, Zn, Ni, Cd). In certain conditions the concentrations for dust, NO2, NH3, SO2(4-), chlorine and Cu were above the maximal accepted levels. Measures should be taken for the prevention and for the elimination of these noxious factors by implementing optimal hygienic conditions (heat, humidity, ventilation), by reducing gas emanations, by using protections equipment (mask, eyeglasses, gloves), and by periodic controls of the health status of dental technicians.

[Bilateral synalgias]

Total pulpitis leads in most cases to unilateral synalgia. Bilateral synalgiae are considerably rarer, but theoretically possible, in which pain radiates to the non-affected half of the jaw or face. Case reports illustrate the symptomatology, cause and therapy.

[Pulpal-periodontal diseases, endodontic therapy and influenza epidemics]

Due to the lowered resistance of the organism, acute pulpitic manifestations without discoverable external cause or exacerbation of chronic periapical processes may occur in the cours of influenza infections. Suggestions for therapy are given on the basic of some case resports.