Dielectric elastomer actuator-based valveless pump as Fontan failure assist device: introduction and preliminary study.

OBJECTIVES: Fontan failure refers to a condition in which the Fontan circulation, a surgical procedure used to treat certain congenital heart defects, becomes insufficient, leading to compromised cardiac function and potential complications. This in vitro study therefore investigates the feasibility of bladeless impedance-driven cavopulmonary assist device via dielectric elastomer actuator (DEA) as a means to address Fontan failure. METHODS: A cavopulmonary assist device, constructed using DEA technologies and employing the impedance pump concept, is subjected to in vitro testing within a closed-loop setup. This study aims to assess the device's functionality and performance under controlled conditions, providing valuable insights into its potential application as a cavopulmonary assistive technology. RESULTS: The DEA-based pump, measuring 50 mm in length and 30 mm in diameter, is capable of achieving substantial flow rates within a closed-loop setup, reaching up to 1.20 l/min at an activation frequency of 4 Hz. It also provides a broad range of working internal pressures (<10 to >20 mmHg). Lastly, the properties of the flow (direction, magnitude, etc.) can be controlled by adjusting the input signal parameters (frequency, amplitude, etc.). CONCLUSIONS: In summary, the results suggest that the valveless impedance-driven pump utilizing DEA technology is promising in the context of cavopulmonary assist devices. Further research and development in this area may lead to innovative and potentially more effective solutions for assisting the right heart, ultimately benefiting patients with heart-related health issues overall, with a particular focus on those experiencing Fontan failure.

Novel para-aortic cardiac assistance using a pre-stretched dielectric elastomer actuator.

OBJECTIVES: We propose an evolution of a dielectric elastomer actuator-based cardiac assist device that acts as a counterpulsation system. We introduce a new pre-stretched actuator and implant the device in a graft bypass between the ascending and descending aorta to redirect all blood through the device (ascending aorta clamped). The objective was to evaluate the influence of these changes on the assistance provided to the heart. METHODS: The novel para-aortic device and the new implantation technique were tested in vivo in 5 pigs. We monitored the pressure and flow in the aorta as well as the pressure-volume characteristics of the left ventricle. Different activation timings were tested to identify the optimal device actuation. RESULTS: The proposed device helps reducing the end-diastolic pressure in the aorta by up to 13 ± 4.0% as well as the peak systolic pressure by up to 16 ± 3.6%. The early diastolic pressure was also increased up to 10 ± 3.5%. With different activation, we also showed that the device could increase or decrease the stroke volume. CONCLUSIONS: The new setup and the novel para-aortic device presented here helped improve cardiac assistance compared to previous studies. Moreover, we revealed a new way to assist the heart by actuating the device at different starting time to modify the left ventricular stroke volume and stroke work.

Longitudinal analysis of systemic ventricular function and atrioventricular valve function after the Norwood procedure.

OBJECTIVES: To evaluate longitudinal systemic ventricular function and atrioventricular valve regurgitation in patients after the neonatal Norwood procedure. METHODS: Serial postoperative echocardiographic images before Fontan completion were assessed in neonates who underwent the Norwood procedure between 2001 and 2020. Ventricular function and atrioventricular valve regurgitation were compared between patients with modified Blalock-Taussig shunt and right ventricle to pulmonary artery conduit. RESULTS: A total of 335 patients were identified including 273 hypoplastic left heart syndrome and 62 of its variants. Median age at Norwood was 8 (7-12) days. Modified Blalock-Taussig shunt was performed in 171 patients and the right ventricle to pulmonary artery conduit in 164 patients. Longitudinal ventricular function and atrioventricular valve regurgitation were evaluated using a total of 4352 echocardiograms. After the Norwood procedure, ventricular function was initially worse (1-30 days) but thereafter better (30 days to stage II) in the right ventricle to pulmonary artery conduit group (P < 0.001). After stage II, the ventricular function was inferior in the right ventricle to the pulmonary artery conduit group (P < 0.001). Atrioventricular valve regurgitation between the Norwood procedure and stage II was more frequent in the modified Blalock-Taussig shunt group (P < 0.001). After stage II, there was no significant difference in atrioventricular valve regurgitation between the groups (P = 0.171). CONCLUSIONS: The effect of shunt type on haemodynamics after the Norwood procedure seems to vary according to the stage of palliation. After the Norwood, the modified Blalock-Taussig shunt is associated with poorer ventricular function and worse atrioventricular valve regurgitation compared to right ventricle to pulmonary artery conduit. Whereas, after stage II, modified Blalock-Taussig shunt is associated with better ventricular function and comparable atrioventricular valve regurgitation, compared to the right ventricle to pulmonary artery conduit.

Comparison of ductus stent versus surgical systemic-to-pulmonary shunt as initial palliation in patients with univentricular heart.

OBJECTIVES: In this study, we aimed to compare infants with univentricular hearts who underwent an initial ductus stenting to those receiving a surgical systemic-to-pulmonary shunt (SPS). METHODS: All infants with univentricular heart and ductal-dependent pulmonary blood flow who underwent initial palliation with either a ductus stenting or a surgical SPS between 2009 and 2022 were reviewed. Outcomes were compared after ductus stenting or SPS including survival, probability of re-interventions and the probability to reach stage II palliations. RESULTS: A total of 130 patients were evaluated, including 49 ductus stenting and 81 SPSs. The most frequent primary diagnosis was tricuspid atresia in 27, followed by pulmonary atresia with intact ventricular septum in 19 patients. There was comparable hospital mortality (2.0% stent vs 3.7% surgery, P = 0.91) between the groups, but shorter intensive care unit stay (median 1 vs 7 days, P < 0.01) and shorter hospital stay (median 7 vs 17 days, P < 0.01) were observed in patients with initial ductus stenting, compared to those with SPS. However, acute procedure-related complications were more frequently observed in patients with ductus stenting, compared with those with SPS (20.4 vs 6.2%, P = 0.01), and 10 patients needed a shunt procedure after the initial ductus stent. The cumulative incidence of reaching stage II was similar between ductus stenting and SPS (88.0 vs 90.6% at 12 months, P = 0.735). Pulmonary artery (PA) index (median 194 vs 219 mm2/m2, P = 0.93) at stage II was similar between patients with ductus stenting and SPS. However, the ratio of the left to the right PA index [0.69 (0.45-0.95) vs 0.86 (0.51-0.84), P = 0.015] was higher in patients who reached stage II with surgical shunt physiology, compared with patients with ductus stent physiology. CONCLUSIONS: After initial ductus stenting in infants with univentricular heart, survival is comparable and post-procedural recovery shorter, but more acute stent dysfunctions and lower development of left PA are observed, compared to acute shunt dysfunctions. The less invasive procedure and shorter hospital stay are at the expense of more stent reinterventions.

Long-Term Survival Is Superior in Patients With Pulsatile Pulmonary Flow After the Björk Procedure.

Background: This study aims to evaluate clinical outcomes and hemodynamic variables late after the Björk procedure, regarding the pulmonary flow pattern. Methods: Patients who survived more than 15 years after the Björk procedure were included and then divided into two groups according to their pulmonary flow pattern by pulsed-wave Doppler assessment of echocardiography: patients with pulsatile systolic pulmonary flow (Group P) and those without (Group N). Results: A total of 43 patients were identified, of whom 13 patients were divided into Group P and 30 in Group N. Median age at the Björk procedure was 5.7 (2.1-7.3) years, and median follow-up was 32 (28-36) years. Survival after 15 years was higher in Group P, compared with Group N (100% vs 76% at 30 years, P = .045). Cardiac catheterization data demonstrated higher cardiac index in Group P patients compared with Group N patients (3.5 vs 2.8 L/m2, P = .014). Cardiac magnetic resonance imaging study revealed that Group P patients had higher right ventricular end-diastolic volume index (96 vs 57 mL/m2, P = .005), higher end-systolic volume index (49 vs 30 mL/m2, P = .013) and higher right ventricular stroke volume index (48 vs 25 mL/m2, P < .001), compared with Group N patients. Exercise capacity tests demonstrated that Group P patients showed a higher percent predicted peak oxygen consumption, compared with Group N patients (73 vs 58%, P < .001). Conclusions: Late after the Björk procedure, patients with a pulsatile systolic pulmonary flow had a larger right ventricle and better exercise capacity compared with those without pulsatile systolic pulmonary flow.

Brady-arrhythmias requiring permanent pacemaker implantation during and after staged Fontan palliation.

BACKGROUND: Brady-arrhythmia requiring pacemaker implantation remains one of the Fontan-specific complications before and after total cavopulmonary connection. METHODS: A retrospective analysis of 620 patients who underwent total cavopulmonary connection between 1994 and 2021 was performed to evaluate the incidence of brady-arrhythmia and the outcomes after pacemaker implantation. Factors associated with the onset of brady-arrhythmia were identified. RESULTS: A total of 52 patients presented with brady-arrhythmia and required pacemaker implantation. Diagnosis included 16 sinus node dysfunctions, 29 atrioventricular blocks, and 7 junctional escape rhythms. Pacemaker implantation was performed before total cavopulmonary connection (n = 16), concomitant with total cavopulmonary connection (n = 8), or after total cavopulmonary connection (n = 28, median 1.8 years post-operatively). Freedom from pacemaker implantation following total cavopulmonary connection at 10 years was 92%. Twelve patients needed revision of electrodes due to lead dysfunction (n = 9), infections (n = 2), or dislocation (n = 1). Lead energy thresholds were stable, and freedom from pacemaker lead revision at 10 years after total cavopulmonary connection was 78%. Congenitally corrected transposition of the great arteries (odds ratio: 6.6, confidence interval: 2.0-21.5, p = 0.002) was identified as a factor associated with pacemaker implantation before total cavopulmonary connection. Pacemaker rhythms for Fontan circulation were not a risk factor for survival (p = 0.226), protein-losing enteropathy/plastic bronchitis (p = 0.973), or thromboembolic complications (p = 0.424). CONCLUSIONS: In our cohort of patients following total cavopulmonary connection, freedom from pacemaker implantation at 10 years was 92% and stable atrial and ventricular lead energy thresholds were observed. Congenitally corrected transposition of the great arteries was at increased risk for pacemaker implantation before total cavopulmonary connection. Having a pacemaker in the Fontan circulation had no adverse effect on survival, protein-losing enteropathy/plastic bronchitis, or thromboembolic complications.

Impact of aortopulmonary collaterals on adverse events after total cavopulmonary connection.

OBJECTIVES: Effects of aortopulmonary collaterals (APCs) on outcomes after the total cavopulmonary connection (TCPC) are unclear. This study evaluated the incidence of APCs before and after TCPC and analysed the impacts of APCs on adverse outcomes. METHODS: A total of 585 patients, who underwent TCPC from 1994 to 2020 and whose preoperative angiographies were available, were included. Pre-TCPC angiograms in all patients were used for the detection of APCs, and post-TCPC angiograms were evaluated in selected patients. Late adverse events included late death, protein-losing enteropathy (PLE) and plastic bronchitis (PB). RESULTS: The median age at TCPC was 2.3 (1.8-3.4) years with a body weight of 12 (11-14) kg. APCs were found in 210 patients (36%) before TCPC and in 81 (14%) after TCPC. The closure of APCs was performed in 59 patients (10%) before TCPC, in 25 (4.2%) at TCPC and in 59 (10%) after TCPC. The occurrences of APCs before and after TCPC were not associated with short-term or mid-term mortality. The APCs before TCPC were associated with chylothorax (P = 0.025), prolonged chest tube duration (P = 0.021) and PB (P = 0.008). The APCs after TCPC were associated with PLE (P < 0.001) and PB (P < 0.001). With APCs following TCPC, freedom from PLE and PB was lower than without (P < 0.001, P < 0.001). CONCLUSIONS: APCs before TCPC were associated with chylothorax, prolonged chest tube duration and PB. APCs after TCPC were associated with both PLE and PB. The presence of APCs might affect the lymph drainage system and increase the incidence of chylothorax, PLE and PB.

Mid-term results following pulmonary artery patch augmentation in congenital heart disease.

Background: Treatment of pulmonary artery (PA) stenosis in congenital heart disease is associated with adverse outcomes. The aim of this retrospective cohort study was to compare outcomes after surgical patch augmentation of PA stenosis in patients with biventricular congenital heart disease using different patch materials. Methods: We identified all patients from our institutional congenital heart disease database who underwent patch augmentation for PA stenosis on the main pulmonary artery (MPA) or PA branches between 2012 and 2018. Patch materials used were glutaraldehyde fixated autologous pericardium (AP), expanded polytetrafluoroethylene (ePTFE), equine pericardium (EP), and bovine pericardium (BP). The primary study endpoint was the composite of catheter-based re-intervention or re-operation to relieve recurrent stenosis at the site of prior implanted patch material. Results: A total of 156 patients (median age, 5 months, range, 0-85 months; median weight, 6.2 kg, range, 2.8-15.0 kg) underwent patch augmentation using 163 patches (ePTFE =99, 61%; EP =34, 21%; AP =25, 15%; BP =5, 3%). Overall, 131 (84%) patients underwent patch augmentation at the MPA, and 25 (16%) patients underwent patch augmentation at one or both PA branches. Over a mean follow-up period of 4±2 years, 30 patients (19%) reached the study endpoint. Freedom from primary endpoint was 92%±3% for the MPA and 25%±9% for PA branches at 5 years, respectively (P<0.001). Comparison of patch materials revealed similar re-intervention rates between ePTFE, AP, and EP. In contrast, outcomes were significantly decreased following the usage of BP when compared to other materials (ePTFE vs. BP, P=0.01; EP vs. BP, P=0.005). In the multivariable analysis, lower weight at index operation, patch augmentation of PA branches, and usage of BP were independently associated with re-intervention. Conclusions: Patch augmentation of the MPA was associated with acceptable outcomes, while patch augmentation of PA branch stenosis remained independently associated with re-intervention. None of the used patch materials demonstrated superiority; however, BP had a higher rate of re-interventions.

Impact of calorie intake and weight gain after Norwood procedure on the outcome of stage II palliation.

BACKGROUND: This study aimed to assess the impact of caloric intake and weight-for-age-Z-score after the Norwood procedure on the outcome of bidirectional cavopulmonary shunt. METHODS: A total of 153 neonates who underwent the Norwood procedure between 2012 and 2020 were surveyed. Postoperative daily caloric intake and weight-for-age-Z-score up to five months were calculated, and their impact on outcome after bidirectional cavopulmonary shunt was analysed. RESULTS: Median age and weight at the Norwood procedure were 9 days and 3.2 kg, respectively. Modified Blalock-Taussig shunt was used in 95 patients and right ventricle to pulmonary artery conduit in 58. Postoperatively, total caloric intake gradually increased, whereas weight-for-age-Z-score constantly decreased. Early and inter-stage mortality before stage II correlated with low caloric intake. Older age (p = 0.023) at Norwood, lower weight (p < 0.001) at Norwood, and longer intubation (p = 0.004) were correlated with low weight-for-age-Z-score (< -3.0) at 2 months of age. Patients with weight-for-age-Z-score < -3.0 at 2 months of age had lower survival after stage II compared to those with weight-for-age-Z-score of -3.0 or more (85.3 versus 92.9% at 3 years after stage II, p = 0.017). There was no difference between inter-stage weight gain and survival after bidirectional cavopulmonary shunt between the shunt types. CONCLUSION: Weight-for-age-Z-score decreased continuously throughout the first 5 months after the Norwood procedure. Age and weight at Norwood and intubation time were associated with weight gain. Inter-stage low weight gain (Z-score < -3) was a risk for survival after stage II.

Impact of home monitoring program on interstage mortality after the Norwood procedure.

Objective: While early outcome after the Norwood operation for hypoplastic left heart syndrome has improved, interstage mortality until bidirectional cavopulmonary shunt (BCPS) remains a concern. Our aim was to institute a home monitoring program to (HMP) decrease interstage mortality. Methods: Among 264 patients who survived Norwood procedure and were discharged before BCPS, 80 patients were included in the HMP and compared to the remaining 184 patients regarding interstage mortality. In patients with HMP, events during the interstage period were evaluated. Results: Interstage mortality was 8% (n = 21), and was significantly lower in patients with HMP (2.5%, n = 2), compared to those without (10.3%, n = 19, p = 0.031). Patients with interstage mortality had significantly lower birth weight (p < 0.001) compared to those without. Lower birth weight (p < 0.001), extra corporeal membrane oxygenation support (p = 0.002), and lack of HMP (p = 0.048) were risk factors for interstage mortality. Most frequent event during home monitoring was low saturation (<70%) in 14 patients (18%), followed by infection in 6 (7.5%), stagnated weight gain in 5 (6.3%), hypoxic shock in 3 (3.8%) and arrhythmias in 2 (2.5%). An unexpected readmission was needed in 24 patients (30%). In those patients, age (p = 0.001) and weight at BCPS (p = 0.007) were significantly lower compared to those without readmission, but the survival after BCPS was comparable between the groups. Conclusions: Interstage HMP permits timely intervention and led to an important decrease in interstage mortality. One-third of the patients with home monitoring program needed re-admission and demonstrated the need for earlier stage 2 palliation.

Tachyarrhythmia after the total cavopulmonary connection: incidence, prognosis, and risk factors.

OBJECTIVE: The purpose of this study is to evaluate the incidence and outcomes regarding tachyarrhythmia in patients after total cavopulmonary connection. METHODS: A retrospective analysis of 620 patients who underwent total cavopulmonary connection between 1994 and 2021 at our institution was performed. Incidence of tachyarrhythmia was depicted, and results after onset of tachyarrhythmia were evaluated. Factors associated with the onset of tachyarrhythmia were identified. RESULTS: A total of 52 (8%) patients presented with tachyarrhythmia that required medical therapy. Onset during hospital stay was observed in 27 patients, and onset after hospital discharge was observed in 32 patients. Freedom from late tachyarrhythmia following total cavopulmonary connection at 5, 10, and 15 years was 97, 95, and 91%, respectively. The most prevalent late tachyarrhythmia was atrial flutter (50%), followed by supraventricular tachycardia (25%) and ventricular tachycardia (25%). Direct current cardioversion was required in 12 patients, and 7 patients underwent electrophysiological study. Freedom from Fontan circulatory failure after onset of tachyarrhythmia at 10 and 15 years was 78% and 49%, respectively. Freedom from occurrence of decreased ventricular systolic function after the onset of tachyarrhythmia at 5 years was 85%. Independent factors associated with late tachyarrhythmia were dominant right ventricle (hazard ratio, 2.52, p = 0.02) and weight at total cavopulmonary connection (hazard ratio, 1.03 per kilogram; p = 0.04). Type of total cavopulmonary connection at total cavopulmonary connection was not identified as risk. CONCLUSIONS: In our large cohort of 620 patients following total cavopulmonary connection, the incidence of late tachyarrhythmia was low. Patients with dominant right ventricle and late total cavopulmonary connection were at increased risk for late tachyarrhythmia following total cavopulmonary connection.

Development of Weight and Height Age z-Score after Total Cavopulmonary Connection.

OBJECTIVE: We aimed to analyze somatic growth of patients after total cavopulmonary connection (TCPC) as well as to identify factors influencing postoperative catch-up growth. METHODS: A total of 309 patients undergoing TCPC at 4 years old or less between 1994 and 2021 were included. Weight for age z-score (WAZ) and height for age-z-score (HAZ) at TCPC and at postoperative time between 1 and 3 years were calculated. Factors influencing somatic growth were analyzed. RESULTS: Most frequent diagnosis and initial palliation were hypoplastic left heart syndrome (HLHS) (34%) and the Norwood procedure (51%), respectively. Median age and weight at TCPC were 2.0 (IQR: 1.7-2.5) years and 11.3 (10.5-12.7) kg, respectively. Median 519 days after TCPC, a significant increase in WAZ (-0.4 to -0.2, p < 0.001) was observed, but not in HAZ (-0.6 to -0.6, p = 0.38). Older age at TCPC (p < 0.001, odds ratio [OR]: 2.6) and HLHS (p = 0.007, OR: 2.2) were risks for low WAZ after TCPC. Older age at TCPC (p = 0.009, OR: 1.9) and previous Norwood procedure (p = 0.021, OR: 2.0) were risks for low HAZ after TCPC. Previous bidirectional cavopulmonary shunt (BCPS) was a protective factor for both WAZ (p = 0.012, OR: 0.06) and HAZ (p = 0.028, OR: 0.30) at TCPC. CONCLUSION: In patients undergoing TCPC at the age of 4 years or less, a significant catch-up growth was observed in WAZ after TCPC, but not in HAZ. Previous BCPS resulted to be a protective factor for a better somatic development at TCPC. HLHSs undergoing Norwood were considered as risks for somatic development after TCPC.

Protein-Losing Enteropathy and Plastic Bronchitis Following the Total Cavopulmonary Connections.

BACKGROUND: We aimed to evaluate incidence, outcomes, and predictors of protein-losing enteropathy (PLE) and plastic bronchitis (PB) in a cohort of total cavopulmonary connection (TCPC). METHODS: We included 620 consecutive patients undergoing TCPC between 1994 and 2021. Prevalence and predictors for onset of PLE/PB were evaluated. Death and heart transplantation after onset of PLE/PB were examined. RESULTS: A total of 41 patients presented with PLE/PB (31 with PLE, 15 with PB, and 5 developed both PLE and PB). Their median age at TCPC was 2.2 (interquartile ranges [IQRs], 1.7-3.7) years, and time period to onset for PLE was 2.6 (IQR: 1.0-6.6) years and for PB was 1.1 (IQR: 0.3-4.1) years after TCPC. Independent factors for developing PLE/PB were dominant right ventricle (RV, hazard ratio [HR], 2.243; 95% confidence interval [CI], 1.129-4.458, P = .021) and prolonged pleural effusion after TCPC (HR, 2.101; 95% CI, 1.090-4.049, P = .027). In PLE/PB population, freedom from death or transplantation after PLE/PB diagnosis at 5 and 10 years were 88.7% and 76.4%, respectively. Eleven surgical interventions were performed in 10 patients, comprising atrioventricular valve repairs (n = 4), Fontan pathway revisions (n = 2), pacemaker implantation (n = 2), secondary fenestration (n = 1), diaphragm plication (n = 1), and ventricular assist device implantation (n = 1). In nine patients, a recovery from PLE with the resolution of PLE symptoms and normal protein levels was achieved. Eight patients died and the remaining continued to have challenging protein loss. CONCLUSIONS: Protein-losing enteropathy and PB remain severe complications in the cohort of TCPC. Patients with dominant RV, and prolonged pleural effusions, were at risk for PLE/PB.

Biogenic polymer-based patches for congenital cardiac surgery: a feasibility study.

Objective: Currently used patch materials in congenital cardiac surgery do not grow, renew, or remodel. Patch calcification occurs more rapidly in pediatric patients eventually leading to reoperations. Bacterial cellulose (BC) as a biogenic polymer offers high tensile strength, biocompatibility, and hemocompatibility. Thus, we further investigated the biomechanical properties of BC for use as patch material. Methods: The BC-producing bacteria Acetobacter xylinum were cultured in different environments to investigate optimal culturing conditions. For mechanical characterization, an established method of inflation for biaxial testing was used. The applied static pressure and deflection height of the BC patch were measured. Furthermore, a displacement and strain distribution analysis was performed and compared to a standard xenograft pericardial patch. Results: The examination of the culturing conditions revealed that the BC became homogenous and stable when cultivated at 29°C, 60% oxygen concentration, and culturing medium exchange every third day for a total culturing period of 12 days. The estimated elastic modulus of the BC patches ranged from 200 to 530 MPa compared to 230 MPa for the pericardial patch. The strain distributions, calculated from preloaded (2 mmHg) to 80 mmHg inflation, show BC patch strains ranging between 0.6% and 4%, which was comparable to the pericardial patch. However, the pressure at rupture and peak deflection height varied greatly, ranging from 67 to around 200 mmHg and 0.96 to 5.28 mm, respectively. The same patch thickness does not automatically result in the same material properties indicating that the manufacturing conditions have a significant impact on durability. Conclusions: BC patches can achieve comparable results to pericardial patches in terms of strain behavior as well as in the maximum applied pressure that can be withstood without rupture. Bacterial cellulose patches could be a promising material worth further research.

Multiscale multimodal characterization and simulation of structural alterations in failed bioprosthetic heart valves.

Calcific degeneration is the most frequent type of heart valve failure, with rising incidence due to the ageing population. The gold standard treatment to date is valve replacement. Unfortunately, calcification oftentimes re-occurs in bioprosthetic substitutes, with the governing processes remaining poorly understood. Here, we present a multiscale, multimodal analysis of disturbances and extensive mineralisation of the collagen network in failed bioprosthetic bovine pericardium valve explants with full histoanatomical context. In addition to highly abundant mineralized collagen fibres and fibrils, calcified micron-sized particles previously discovered in native valves were also prevalent on the aortic as well as the ventricular surface of bioprosthetic valves. The two mineral types (fibres and particles) were detectable even in early-stage mineralisation, prior to any macroscopic calcification. Based on multiscale multimodal characterisation and high-fidelity simulations, we demonstrate that mineral occurrence coincides with regions exposed to high haemodynamic and biomechanical indicators. These insights obtained by multiscale analysis of failed bioprosthetic valves serve as groundwork for the evidence-based development of more durable alternatives. STATEMENT OF SIGNIFICANCE: Bioprosthetic valve calcification is a well-known clinically significant phenomenon, leading to valve failure. The nanoanalytical characterisation of bioprosthetic valves gives insights into the highly abundant, extensive calcification and disorganization of the collagen network and the presence of calcium phosphate particles previously reported in native cardiovascular tissues. While the collagen matrix mineralisation can be primarily attributed to a combination of chemical and mechanical alterations, the calcified particles are likely of host cellular origin. This work presents a straightforward route to mineral identification and characterization at high resolution and sensitivity, and with full histoanatomical context and correlation to hemodynamic and biomechanical indicators, hence providing design cues for improved bioprosthetic valve alternatives.

Outcome of Stanford type B dissection in patients with Marfan syndrome.

OBJECTIVES: The aim of this study was to determine the outcome of Stanford type B aortic dissection in patients with Marfan syndrome (MFS) and to evaluate aortic diameters at time of dissection as well as the impact of previous aortic root replacement. METHODS: Analysis of all patients with MFS fulfilling Ghent criteria seen at this institution since 1995 until 2022. RESULTS: Thirty-six (19%) out of 188 patients with MFS suffered from Stanford type B aortic dissection during the study period. The Mean aortic diameter at the time of dissection was 39.0 mm [95% confidence interval (CI): 35.6-42.3]. The mean pre-dissection diameter (available in 25% of patients) was 32.1 mm (95% CI: 28.0-36.3) and the mean expansion was 19% (95% CI: 11.9-26.2). There was no correlation between age and diameter at the time of dissection (<20, 21-30, 31-40, 41-50, 51-60, <61 years; P = 0.78). Freedom from intervention after dissection was 53%, 44% and 33% at 1, 5 and 10 years. Aortic growth rate in those patients that had to undergo intervention within the 1st year after dissection was 10.2 mm/year (95% CI: 4.4-15.9) compared to 5.8 mm/year (95% CI: 3.3-8.3, P = 0.109) in those thereafter. The mean time between dissection and intervention was 1.8 years (95% CI: 0.6-3.0). While type B dissection seems more frequent after previous elective aortic repair (58% vs 42%), there was no difference between valve-sparing root replacement (VSRR) compared to Bentall procedures [Hazard ratio (HR) for VSRR 0.78, 95% CI: 0.31-2.0, P-value = 0.61]. The mean age of the entire population at the end of follow-up was 42 years (95% CI: 39.2-44.7). The mean follow-up time was 9 years (95% CI: 7.8-10.4). CONCLUSIONS: Stanford type B dissection in patients with MFS occurs far below accepted thresholds for intervention. Risk for type B dissection is present throughout lifetime and two-thirds of patients need an intervention after dissection. There is no difference in freedom from type B dissection between a Bentall procedure and a VSRR.

A novel soft cardiac assist device based on a dielectric elastomer augmented aorta: An in vivo study.

Although heart transplant is the preferred solution for patients suffering from heart failures, cardiac assist devices remain key substitute therapies. Among them, aortic augmentation using dielectric elastomer actuators (DEAs) might be an alternative technological application for the future. The electrically driven actuator does not require bulky pneumatic elements (such as conventional intra-aortic balloon pumps) and conforms tightly to the aorta thanks to the manufacturing method presented here. In this study, the proposed DEA-based device replaces a section of the aorta and acts as a counterpulsation device. The feasibility and validation of in vivo implantation of the device into the descending aorta in a porcine model, and the level of support provided to the heart are investigated. Additionally, the influence of the activation profile and delay compared to the start of systole is studied. We demonstrate that an activation of the DEA just before the start of systole (30 ms at 100 bpm) and deactivation just after the start of diastole (0-30 ms) leads to an optimal assistance of the heart with a maximum energy provided by the DEA. The end-diastolic and left ventricular pressures were lowered by up to 5% and 1%, respectively, compared to baseline. The early diastolic pressure was augmented in average by up to 2%.

Longitudinal analysis of systemic ventricular function and atrioventricular valve function after the Fontan procedure.

OBJECTIVES: This study aimed to determine the longitudinal change of systemic ventricular function and atrioventricular valve (AVV) regurgitation after total cavopulmonary connection (TCPC). METHODS: In 620 patients who underwent TCPC between 1994 and 2021, 4219 longitudinal echocardiographic examinations of systemic ventricular function and AVV regurgitation were evaluated retrospectively. RESULTS: The most frequent primary diagnosis was hypoplastic left heart syndrome in 172, followed by single ventricle in 131, tricuspid atresia in 95 and double inlet left ventricle (LV) in 91 patients. Dominant right ventricle (RV) was observed in 329 (53%) and dominant LV in 291 (47%). The median age at TCPC was 2.3 (1.8-3.4) years. Transplant-free survival at 5, 10 and 15 years after TCPC was 96.3%, 94.7% and 93.6%, respectively, in patients with dominant RV and 97.3%, 94.6% and 94.6%, respectively, in those with dominant LV (P = 0.987). Longitudinal analysis of systemic ventricular function was similar in both groups during the first 10 years postoperatively. Thereafter, systemic ventricular function worsened significantly in patients with dominant RV, compared with those with dominant LV (15 years: P = 0.007, 20 years: P = 0.03). AVV regurgitation was more frequent after TCPC in patients with dominant RV compared with those with dominant LV (P < 0.001 at 3 months, 3 years, 5 years, 10 years and 15 years, P = 0.023 at 20 years). There was a significant correlation between postoperative systemic ventricular dysfunction and AVV regurgitation (P < 0.001). CONCLUSIONS: There were no transplant-free survival difference and no difference in ventricular function between dominant RV and dominant LV for the first 10 years after TCPC. Thereafter, ventricular function in dominant RV was inferior to that in dominant LV. The degree of AVV regurgitation was significantly higher in dominant RV, compared with dominant LV, and it was positively associated with ventricular dysfunction, especially in dominant RV.