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Objectives: To increase the safety of aortic valve replacement, we developed the 'Caput medusae' method, where the prosthesis is prefixed with circumferential tourniquets prior to knot tying. We assumed that an even distribution of forces may help reduce tissue damage. To confirm this theoretically, we compared forces between knots and tourniquets., Methods: The experimental set-up included a device with movable acrylic plates, a mounted valve and a set of sutures. Traction forces were measured with a luggage scale. Two different tourniquets were compared individually and as bundles of 15. Force-path curves were generated. Knotting and tourniquet forces of 18 staff surgeons were then compared. Both modalities were measured 10 times on 2 days, resulting in 40 observations per surgeon, or 360 observations per modality., Results: Polyvinyl chloride tourniquets were stiffer than silicone, expressed by a 1.5- to 1.7-fold higher regression-line slope. Fifteen simultaneous tubes produced force increments 7.9-8.9 times higher than their single counterparts. Overall knotting force was 13.64 ± 5.76 vs tourniquet 1.08 ± 0.48 N. Male surgeons' knotting forces were higher compared to female staff (14.76 ± 6.01 vs 10.73 ± 3.74 N; P < 0.001) while tourniquet forces did not differ (1.09 ± 0.47 vs 1.05 ± 0.49 N; P = 0.459). Dedicated valve surgeons (n = 10) tightened the tourniquets more strongly than inexperienced surgeons (1.20 ± 0.52 vs 0.94 ± 0.37 N; P < 0.001); knotting was similar. Multivariable analysis confirmed only valve experience as a predictor of tourniquet strength (experienced surgeons exerted higher force)., Conclusions: Tourniquets exert less force on the tissue than knots. When distributed over the circumference, they can reduce local tension and avoid potential paravalvular leakage. Complete or partial use of tourniquets may thus be an additional option to enhance surgical safety., (© The Author(s) 2020. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Objectives: The invention of new surgical procedures requires testing at different stages including animal models. To facilitate this process, we have developed a computer-controlled extracorporeal circulation system for testing of an explanted porcine heart simulating a variety of physiological parameters. Mitral valve function can be assessed before and after induced valve insufficiency and after valve repair. Accordingly, techniques and instruments can be modified at early stages of prototype development., Methods: In the diastole, the left atrium is passively filled through the reservoir. The loading pressure of the atrium and flow rates can be widely adjusted. To simulate the systole, a linear motor-driven piston pump promotes volume into the left ventricle and the aorta. An additional circulatory pump compensates for undesired total emptying of the heart chambers. The processor control of the linear pump allows for various settings of flow rate, velocity and even irregular rhythm. Twenty-one isolated porcine hearts were used. The leaflet movement was filmed using a universal serial bus (USB)-probe camera., Results: With 80 mm stroke and 1 m/s speed, a volume of 150 ml can be pumped at a heart rate of up to 73 bpm. Cardiac outputs of up to 10.9 l/min can be achieved. Constant visualization and continuous measurements of the pressure gradients before and after the induction of mitral insufficiency and after repair allowed quantitative verification of repair quality under beating-heart conditions., Conclusions: This model allows a controllable pulsation, loading and unloading of a porcine heart in a wide range. Thus, the function of the leaflets and repair results can be qualitatively and quantitatively evaluated under quasiphysiological conditions., (© The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Interrupted pledget-armed braided sutures are widely used for valve implantation. In a 74-year-old woman with aortic valve endocarditis and shallow annular abscess, annulus dehiscence resulted after resection. As resistance was too high for sufficient primary approximation, a snug fit of the valve by means of circumferential application of curbed tourniquets resembling Medusa's head after suture placement was achieved. Closest possible approximation of the upper and lower part of the annulus with the prosthesis prior to final fixation was thus possible, so that application of too much tension on a single suture could be avoided., (© The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Objectives: Obesity is an ever-growing problem in contemporary cardiac surgery. Although it accounts for many perioperative comorbidities, it has not been shown to increase mortality. Body mass index (BMI) is therefore not considered in the European System for Cardiac Operative Risk Evaluation (EuroSCORE). We sought to confirm whether this holds true for our own single-centre patient population., Methods: Data from 15 314 consecutive patients receiving major cardiac surgery at our institution were analysed. Gender, age, BMI, EuroSCORE, urgency, redo status and all-cause in-hospital mortality were derived from our database. Mortality was grouped into 4 BMI categories. We created a logistic regression model to identify predictors of mortality., Results: There were 11 034 males and 4280 females. Categorical mortality was 8.79% (underweight), 7.04% (normal weight), 5.16% (overweight), 6.30% (obese), rendering an inverse J-shaped pattern known as obesity paradox. Univariable regression detected significant predictors of mortality: rising age, female gender, urgent procedures, redo surgery ( P  < 0.001). BMI was no predictor ( P  = 0.575) but became significant with the multivariable analysis ( P  = 0.004). Its effect on mortality was exclusively indirect, being mediated through age ( P  < 0.001). Receiver-operating characteristics curve analysis also confirmed that BMI did not qualify as a risk factor. However, the overweight category was a predictor of lower mortality., Conclusions: Our findings from >15 000 patients confirm the obesity paradox showing the least mortality in the overweight group. They support the current EuroSCORE model in that BMI is no independent predictor of early mortality. However, such patients still carry the risk of comorbidities. Likewise, special care is required with underweight patients who show the highest in-hospital mortality., (© The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Endovascular valves have become a valid option for patients not qualifying for conventional surgery. Biological valves mounted in a stent are currently used. After implantation, however, geometrical distortion of the valve can occur. We tested whether biological valves suitable for transcatheter implantation exhibit hemodynamic deficits after deployment in a distorted position. Two types of valves [bovine pericardium (BP) and porcine cusps], of 21 and 23 mm diameter, respectively were investigated. Mean transvalvular gradient (TVG), effective orifice area (EOA), and regurgitation fraction (REG) were measured prior to and after the 20% distortion of the original diameter. All valves exhibited an increase of TVG and reduction of EOA whereas REG increased only in BP valves after distortion. The 21 mm valves demonstrated a more pronounced alteration than the 23 mm valves. Even moderately distorted implantation of a biological valve results in a marked functional alteration. The susceptibility of pericardial valves is higher than that of porcine valves probably owing to better coaptation properties of native cusps even under deformed conditions when compared to valves constructed with pericardium. Care should therefore be taken during implantation of endovascular valves in order to avoid fixed hemodynamic deficits. Native valves may preferably be used as they demonstrate a more robust behavior regarding suboptimal implantation.

Various techniques of stentless aortic valve implantation with or without wall components exist. We investigated the in-vitro performance of stentless valves without or with aortic wall removal mimicking root versus subcoronary implantation. Glutaraldehyde-preserved stentless aortic valves (gpSVG), cryo-preserved human homografts (cpHG), cryo-preserved xenografts (cpXG), and fresh xenografts (fXG) were used. Valves were mounted as full roots or trimmed in a mock circuit. Mean transvalvular gradient (MTVG, mmHg) was measured. Distensibility was quantified using post-systolic backflow volume (BV, ml) - after valve closure. Function was visualized by means of a high-speed camera. Glutaraldehyde-preserved valves exhibited higher MTVG than cryo-preserved or fresh substitutes. After trimming, cpHG, cpXG, and fXG demonstrated marked reduction of MTVG (cpHG: 7.6-5.2 mmHg; cpXG: 6.7-4.9 mmHg; fXG: 8.4-5.2 mmHg). In contrast, after trimming gpSVG exhibited a significant increase of MTVG (7.1-9.2 mmHg). BV remained constant. Visualization indicated maintained distension of all valves and types of all sizes after trimming. In fresh and cryo-preserved grafts, aortic wall trimming resulted in significantly improved systolic performance while glutaraldehyde-preserved stentless valves demonstrated systolic impairment after wall resection. Subcoronary implantation of fresh or cryo-preserved aortic valves may therefore be preferred. In contrast, glutaraldehyde-preserved valves are dependent on wall suspension and may therefore be implanted as a root.

Surgical treatment of a Jehovah's Witnesses continues to be a great challenge in cardiac surgery. Different strategies are used to minimize the risk for early mortality, prolonged intensive care unit stay and hospitalization, resulting from anemia. Minimized closed circuit extracorporeal circulations have been shown to reduce adverse effects of conventional CPB. Two patients underwent urgent coronary revascularization for triple-vessel disease. The miniECC (Stöckert) is a phosphorylcholine-coated device which integrates the functions of oxygenation, filtration, and pumping in a compact manner with reduced total surface area and priming volume. After a well-tolerated operation the patients showed only minimal red blood cell damage (free hemoglobin 93 mg/l). Hematocrit levels decreasing perioperatively in both patients only moderately (32% and 30%). In these two instances using miniECC we showed a markedly reduced blood cell damage and myocardial trauma. Furthermore, we observed hematocrit levels being higher as compared to standard CABG patients, providing an optimized startpoint for an uneventful postoperative course. MiniECC can be routinely employed and reduces red blood cell damage. Therefore, it can be an effective aid in CABG operations in Jehovah's Witnesses.

The purpose of this study was to examine the feasibility of the combined use of intraluminal biodegradable shunts and surgical adhesives for sutureless distal coronary anastomosis. Eighteen LITA-LAD anastomoses were created in a porcine beating heart model. In group I (n=9) a custom-made silicone Y-shunt provided internal stability, while three different adhesives, N-butyl-2-cyanoacrylate-glue (CYAC); albumin-glutaraldehyde-glue (AG); fibrin-glue (FIB), were applied externally. In group II (n=9) biodegradable polydioxanone (PDS) shunts were used. All anastomoses were examined intraoperatively by flow measurement, blood leakage was quantified and physical strength was tested. In all pigs anastomoses could be created successfully at first attempt, but anastomotic leaks requiring additional sutures occurred in 6 animals. LITA-flow significantly decreased in both groups. A patency rate of 89.9% (8/9) was found in group I while it was 66.6% (5/9) in group II. The lowest amount of blood-loss was measured when CYAC adhesive was used while tensile strength was lowest in the FIB-anastomoses. Preliminarily we could demonstrate the feasibility of performing sutureless distal coronary anastomosis by means of a combination of adhesives and temporary intraluminal shunts. PDS-shunts, however, resulted in a high graft-occlusion rate, so that potentially less thrombotic materials need to be investigated.

Closed circuit extracorporeal circulation comprising a centrifugal pump has been developed to reduce deleterious effects of standard cardiopulmonary bypass. This study compares such a system with standard extracorporeal circulation (ECC). Twenty patients underwent isolated routine coronary artery revascularization. Ten patients underwent ECC. Ten patients were operated upon using a closed circuit/centrifugal pump system with coated surfaces (ISS) (SYNERGY, Stöckert). Both groups did not differ regarding age, body mass, left ventricular function, number of bypasses, and concomitant diseases. Free hemoglobin (fHb), plasmin-antiplasmin complex (PAPc), platelet function (ROTEG), and interleukin 6 (IL-6) were measured preoperatively, intraoperatively (after sternotomy, during X-Clamp, during reperfusion, post ECC or ISS), and postoperatively. Technical problems were not observed. The ISS group demonstrated significantly less fHb during bypass, a lower intraoperative myocardial damage as well as less increase in IL-6 after bypass and postoperatively compared to ECC. In ISS fluid balance was significantly lower than in ECC whereas drainage loss and hospitalization did not differ statistically. Extracorporeal circulation with a closed circuit/centrifugal pump system can be routinely employed and appears to be safe. Intraoperative and early postoperative reduction of red blood cell trauma and inflammation are of potential value.

This report describes the case of a 60-year-old man, who developed a giant punch-hole aneurysm of the ascending aorta five month after uncomplicated coronary artery bypass grafting (CABG) due to a localized rupture of the ascending aorta. The patient underwent surgical repair with cardiopulmonary bypass. Because the false aneurysm was adherent to the sternum, resternotomy was performed in deep hypothermia and circulatory arrest. The lesion in the ascending aorta was closed by means of a dacron-patch. The postoperative course of the patient was completely uneventful. We recommend to repair a false aneurysm of the ascending aorta in deep hypothermic circulatory arrest (DHCA) in order to avoid excessive blood loss during sternotomy.