P1000Do patients with atrial fibrillation being at high-risk for stroke benefit from concomitant left atrial appendix closure during cardiac surgery

Background

Left atrial appendix, as an essential source of systemic embolism and stroke in patients with atrial fibrillation, can be excluded during cardiac surgery, however the clinical benefit is as yet uncertain.

Methods

A total of 376 out of 3741 consecutive patients with atrial fibrillation presenting a high risk for stroke (CHA2DS2-VASc-Score ≥2 for men and ≥3 for women) who underwent heart surgery with cardiopulmonary bypass between 01/2012 and 12/2015 were analysed for mortality and stroke rate at 30 days, 12 and 24 months. Patients with concomitant LAA-closure alone (group1; n=107) were compared to patients with concomitant surgical ablation and LAA-closure (group2; n=85), and patients without surgical ablation and no LAA-closure (group3; n=184) as controls. To further adjust for pre- and intraoperative risk factors, a propensity score stratification analysis based on patients age, gender, EuroSCORE-2, CHA2DS2-VASc-Score and type of procedure was performed.

Results

Patients age was 72±8 years (mean±SD) and 33% were female. EuroSCORE-2 was 8.7±7.7%, 5.7±3.9%, and 5.4±8.4% and CHA2DS2-VASc-Score was 4.2±1.5, 3.9±1.4, and 4.1±1.4 on average for the respective groups. Mortality did not differ between groups at 30 days, 12 and 24 months. The incidence of stroke was 1.9% at 30 days, 4.8% at 12 and 6.7% at 24 months in group1. There was no stroke at 30 days and 12 months and 1.3% at 24 months in group2, and 1.8% at 30 days, 3.0% at 12 and 24 months in control group3. The overall mortality at 24 months was 27.1%, 20% and 24.6% respectively. After propensity score stratification, stroke rate showed significant benefit in group 2 (P=0.05) at 12 months and a hazard ratio of 0.17, 95% confidents limits 0.02–1.50, (P=0.08) at 24 months, whereas overall mortality did not significantly differ between the groups at 12 and 24 months follow-up.

Conclusions

In this propensity score stratification analysis, patients undergoing cardiac surgery with surgical ablation and concomitant LAA-closure had significant fewer strokes at 12 months follow-up compared to patients undergoing cardiac surgery with LAA-closure alone. Overall mortality did not significantly differ between the groups. Therefore, a concomitant LAA closure during heart surgery without additional surgical ablation does not show any clinical benefit in terms of reduced stroke rate or survival until 12 and 24 months follow-up.

Streamlined bioreactor-based production of human cartilage tissues

Engineered tissue grafts have been manufactured using methods based predominantly on traditional labour-intensive manual benchtop techniques. These methods impart significant regulatory and economic challenges, hindering the successful translation of engineered tissue products to the clinic. Alternatively, bioreactor-based production systems have the potential to overcome such limitations. In this work, we present an innovative manufacturing approach to engineer cartilage tissue within a single bioreactor system, starting from freshly isolated human primary chondrocytes, through the generation of cartilaginous tissue grafts. The limited number of primary chondrocytes that can be isolated from a small clinically-sized cartilage biopsy could be seeded and extensively expanded directly within a 3D scaffold in our perfusion bioreactor (5.4 ± 0.9 doublings in 2 weeks), bypassing conventional 2D expansion in flasks. Chondrocytes expanded in 3D scaffolds better maintained a chondrogenic phenotype than chondrocytes expanded on plastic flasks (collagen type II mRNA, 18-fold; Sox-9, 11-fold). After this "3D expansion" phase, bioreactor culture conditions were changed to subsequently support chondrogenic differentiation for two weeks. Engineered tissues based on 3D-expanded chondrocytes were more cartilaginous than tissues generated from chondrocytes previously expanded in flasks. We then demonstrated that this streamlined bioreactor-based process could be adapted to effectively generate up-scaled cartilage grafts in a size with clinical relevance (50 mm diameter). Streamlined and robust tissue engineering processes, as the one described here, may be key for the future manufacturing of grafts for clinical applications, as they facilitate the establishment of compact and closed bioreactor-based production systems, with minimal automation requirements, lower operating costs, and increased compliance to regulatory guidelines.

Risk Factors for Bleeding Complications after Percutaneous Dilatational Tracheostomy: A Ten-year Institutional Analysis

Summary

Bleeding complications after percutaneous dilatational tracheostomy (PDT) are infrequent but may have a tremendous impact on a patient's further clinical course. Therefore, it seems necessary to perform risk stratification for patients scheduled for PDT. We retrospectively reviewed the records of 1001 patients (46% male, mean age 68.1 years) undergoing PDT (using the Ciaglia Blue Rhino® technique with direct bronchoscopic guidance) in our cardiothoracic ICU between January 2003 and February 2013. Patients were stratified into two groups: patients suffering acute moderate, severe, or major bleeding (Group A) and patients who had no or only mild bleeding (Group B). In the majority of patients, no or only mild bleeding during PDT occurred (none: 425 [42.5%], mild: 488 [48.8%]). In 84 patients (8.4%), bleeding was classified as moderate. Three patients suffered from severe bleeding; only one major bleed with need for emergency surgery occured. Patients in Group A had a significantly higher Simplified Acute Physiology Score on the day of PDT ( P=0.042), higher prevalence of renal replacement therapy on the day of PDT ( P=0.026), higher incidence of coagulopathy ( P=0.043), lower platelet counts ( P=0.037), lower fibrinogen levels ( P=0.012), higher proportion of PDTs performed by residents ( P=0.034) and higher difficulty grading of PDT ( P=0.001). Using logistic regression analyses, difficult PDT, less experienced operator, Simplified Acute Physiology Score >40 and low fibrinogen levels were independent predictors of clinically significant bleeding after PDT.

A novel calcium scoring system accurately predicts likelihood and location of post-TAVI paravalvular leak

AIM

Sclerosis distribution, topography and morphology in aortic stenosis may have an impact on the localisation of post-procedural paravalvular leakage (PVL) following transcatheter aortic valve implantation (TAVI).

METHODS

Between 05/2005 and 03/2011 a total of 208 patients underwent either transapical (TA) or transvascular (TV) TAVI using the Edwards-SAPIEN(TM), or CoreValve(TM) system. Aortic cusp and annular sclerosis distribution and aortic valve sclerosis symmetry were evaluated by preoperative transesophageal echocardiography (TOE). Mild, moderate and severe PVL after TAVI (group 1, N.=117) were analysed and compared to those patients with no signs of postprocedural PVL (group 2, N.=91). Commercial available image processing and analysing software were used to evaluate all relevant calcific sections (aortic sclerosis score 0-66; symmetry score 0-5) and were matched with the localization of the PVLs.

RESULTS

A total of 117 patients (83±6 years, mean logistic EuroSCORE 20.1±12.7%) were identified with a mild-moderate PVL (TV, N.=102; TA, N.=15). Mean aortic sclerosis score was 38.7±7.6 in group 1 compared to 33.7±8.3 in group 2 (P<0.001) showing highest calcification in the non-coronary part for both groups. The mean symmetry score was 1.9±1.0 group 1 compared to 1.7±1.0 in group 2 (P=0.12). Regression analysis showed a significant relation of preoperative cusp localisation to the corresponding paravalvular leakage (P<0.001).

CONCLUSION

The present study shows that a aortic sclerosis score constructed by TOE enables prediction of postoperative PVL and moreover, the localisation of PVL after TAVI correlates with the corresponding preoperative amount of sclerosis for each cusp.

[Angioscopy: a new intraoperative diagnostic and interventional tool for thoracic aortic treatment]

In complex thoracic aortic disease endovascular techniques and the use of hybrid stent grafts enables a combination therapy of the aortic arch and the descending aorta through a median sternotomy. This emphasizes the importance of intraoperative visualization of the descending aorta and its pathologies. Intraoperative angioscopy is a new diagnostic method for the assessment of distal aortic disease and assists in therapeutic decision-making and navigation of endovascular techniques in the descending aorta. This study presents the angioscopic results of 62 patients (mean age 60±12 years, 73% male, 54 aortic dissections, eight aortic aneurysms) during surgery of the thoracic aorta. Visualization of the extent of pathology along the downstream aorta was feasible in all patients. The implantation of a hybrid stent graft prosthesis was assisted by angioscopy in 34 patients and endovascular balloon dilatation of the stent graft was navigated by angioscopy in 11 patients. Angioscopy has become an indispensable tool in the intraoperative treatment of complex thoracic aortic disease in our clinic, particularly in the navigation of endovascular interventions in the distal thoracic aorta through the aortic arch.

Towards trends in minimal invasive cardiac surgery

While various minimally invasive techniques have been established in many other surgical specialties during the last decades, cardiac surgery has been one of the last domains to adopt the principles of minimally invasive techniques. This was mainly based on the reduced surgical exposure in highly complex cardiac operations and the missing technical requirements in the beginning of the modern cardiac era. Nowadays, technical conditions have continuously improved and have become routine also in cardiac surgery. Most of these novel minimal-invasive concepts have been developed in order to treat high-risk or inoperable patients by reducing operative trauma. Actually, since more high-risk and multimorbid patients were referred for surgery, these initial extraordinary procedures have been adopted into daily clinical routine. Currently, many promising innovations aim to reduce the operative trauma and perioperative morbidity, and furthermore, to increase patients' satisfaction and security. It is anticipated that in the future this current trend towards minimal invasiveness will increase further due to an increased demand, and therefore, such minimal-invasive procedures will become less complex and straightforward.

On-line monitoring of oxygen as a non-destructive method to quantify cells in engineered 3D tissue constructs

Regulatory guidelines have established the importance of introducing quantitative quality controls during the production and/or at the time of release of cellular grafts for clinical applications. In this study we aimed to determine whether on-line measurements of oxygen can be used as a non-destructive method to estimate the number of chondrocytes within an engineered cartilage graft. Human chondrocytes were seeded and cultured in a perfusion bioreactor, and oxygen levels in the culture medium were continuously monitored at the inlet and outlet of the bioreactor chamber throughout the culture period. We found that the drop in oxygen across the perfused construct was linearly correlated with the number of cells per construct (R(2)  = 0.82, p < 0.0001). The method was valid for a wide range of cell numbers, including cell densities currently used in the manufacture of cartilage grafts for clinical applications. Given that few or no non-destructive assays that quantitatively characterize an engineered construct currently exist, this non-invasive method could represent a relevant instrument in regulatory compliant manufacturing of engineered grafts meeting specific quality criteria.