UV radiation enhanced oxygen vacancy formation caused by the PLD plasma plume.

Pulsed Laser Deposition is a commonly used non-equilibrium physical deposition technique for the growth of complex oxide thin films. A wide range of parameters is known to influence the properties of the used samples and thin films, especially the oxygen-vacancy concentration. One parameter has up to this point been neglected due to the challenges of separating its influence from the influence of the impinging species during growth: the UV-radiation of the plasma plume. We here present experiments enabled by a specially designed holder to allow a separation of these two influences. The influence of the UV-irradiation during pulsed laser deposition on the formation of oxygen-vacancies is investigated for the perovskite model material SrTiO3. The carrier concentration of UV-irradiated samples is nearly constant with depth and time. By contrast samples not exposed to the radiation of the plume show a depth dependence and a decrease in concentration over time. We reveal an increase in Ti-vacancy-oxygen-vacancy-complexes for UV irradiated samples, consistent with the different carrier concentrations. We find a UV enhanced oxygen-vacancy incorporation rate as responsible mechanism. We provide a complete picture of another influence parameter to be considered during pulsed laser depositions and unravel the mechanism behind persistent-photo-conductivity in SrTiO3.

Structural properties of templated Ge quantum dot arrays: impact of growth and pre-pattern parameters.

In this study we analyze the impact of process and growth parameters on the structural properties of germanium (Ge) quantum dot (QD) arrays. The arrays were deposited by molecular-beam epitaxy on pre-patterned silicon (Si) substrates. Periodic arrays of pits with diameters between 120 and 20 nm and pitches ranging from 200 nm down to 40 nm were etched into the substrate prior to growth. The structural perfection of the two-dimensional QD arrays was evaluated based on SEM images. The impact of two processing steps on the directed self-assembly of Ge QD arrays is investigated. First, a thin Si buffer layer grown on a pre-patterned substrate reshapes the pre-pattern pits and determines the nucleation and initial shape of the QDs. Subsequently, the deposition parameters of the Ge define the overall shape and uniformity of the QDs. In particular, the growth temperature and the deposition rate are relevant and need to be optimized according to the design of the pre-pattern. Applying this knowledge, we are able to fabricate regular arrays of pyramid shaped QDs with dot densities up to 7.2 × 1010 cm-2.

High frequency spinal cord stimulation-New method to restore cough.

Spinal cord stimulation (SCS, 50Hz) is a useful method to restore an effective cough in persons with spinal cord injury (SCI). However, high stimulus amplitudes and potential activation of pain fibers, significantly limits this application. It is our hypothesis that high frequency SCS (HF-SCS), with low stimulus amplitudes may provide the same level of expiratory muscle activation. In 6 dogs, the effects of SCS, with varying stimulus parameters on positive pressure (P) generation was evaluated. At any given level of stimulus current, mean P was largest at 500Hz, compared to all other stimulus frequencies. For example, with stimulation at 1mA and frequencies of 200, 500 and 600Hz, P were 25±3, 58±4, 51±6cmH2O, respectively. By comparison, P achieved with conventional SCS parameters was 61±5cmH2O. HF-SCS results in a comparable P compared to that achieved with conventional stimulus parameters but with much lower stimulus amplitudes. This method may be useful to restore cough even in subjects with intact sensation.

[Percentiles of body mass index of 18-80-year-old German adults based on data from the Second National Nutrition Survey]. / Perzentilen des Body-Mass-Index auch für 18- bis 80-Jährige? Daten der Nationalen Verzehrsstudie II.

BACKGROUND: Obesity is associated with an increasing risk of morbidity and mortality. The World Health Organization (WHO) defines obesity as a body mass index (BMI) > or = 30.0 kg/m2. In contrast, percentiles depending on age and sex are used in adolescence. DATA AND METHODS: Using the LMS method, age and gender specific BMI percentiles for adulthood are estimated. Data basis is the Second Germany National Nutrition Survey (NVS II) which was surveyed in 2005 and 2006. This study is representative for the German population, and it is based on more than 13,000 adults. RESULTS: Percentiles increase in both sexes with age. It can be observed in females in nearly all age groups. In males, percentiles are saturated around the sixth decade. Only 9 % of 20 to 29 years old adults are obese using WHO criteria, while there are 29 % of 60 to 69 years old adults having a BMI > or = 30.0 kg/m2. CONCLUSIONS: Percentiles reflect age and sex dependencies of the BMI. They show that there is a larger part of the population in higher BMI intervals with increasing age. Thus, the adequacy of the WHO definition should be questioned. Based on the NVS II, current and representative BMI percentiles for adulthood are now available for Germany. These can be used as base for age and sex dependent evaluation of the BMI.

Successful use of recombinant factor VIIa in a patient with intractable bleeding during extracorporeal membrane oxygenation.

Bleeding is still the most common complication during extracorporeal membrane oxygenation (ECMO) for temporary cardio-circulatory support. We present a case of a young man suffering from intractable hemorrhage during ECMO support, who was pre-treated with glycoprotein IIb/IIIa receptor antagonist Tirofiban due to a suspicion of myocardial ischemia. After failure of conventional hemostatic means, hemostasis was achieved by the donation of recombinant Factor VIIa (rFVIIa). Aspects of bleeding control during extracorporeal circulatory support, the use of Tirofiban and rFVIIa are discussed.

Prediction of fluid responsiveness in patients during cardiac surgery.

BACKGROUND: Left ventricular stroke volume variation (SVV) has been shown to be a predictor of fluid responsiveness in various subsets of patients. However, the accuracy and reliability of SVV are unproven in patients ventilated with low tidal volumes. METHODS: Fourteen patients were studied immediately after coronary artery bypass grafting (CABG). All patients were mechanically ventilated in pressure-controlled mode [tidal volume 7.5 (1.2) ml kg(-1)]. In addition to standard haemodynamic monitoring, SVV was assessed by arterial pulse contour analysis. Left ventricular end-diastolic area index (LVEDAI) was determined by transoesophageal echocardiography. A transpulmonary thermodilution technique was used for measurement of cardiac index (CI), stroke volume index (SVI) and intrathoracic blood volume index (ITBI). All variables were assessed before and after a volume shift induced by tilting the patients from the anti-Trendelenburg (30 degrees head up) to the Trendelenburg position (30 degrees head down). RESULTS: After the change in the Trendelenburg position, SVV decreased significantly, while CI, SVI, ITBI, LVEDAI, central venous pressure (CVP) and pulmonary artery occlusion pressure (PAOP) increased significantly. Changes in SVI were significantly correlated to changes in SVV (r=0.70; P<0.0001) and to changes in LVEDAI, ITBI, CVP and PAOP. Only prechallenge values of SVV were predictive of changes in SVI after change from the anti-Trendelenburg to the Trendelenburg position. CONCLUSIONS: In patients after CABG surgery who were ventilated with low tidal volumes, SVV enabled prediction of fluid responsiveness and assessment of the haemodynamic effects of volume loading.

Comparison of ultrasonic scalpel versus argon-beam and conventional electrocautery for internal thoracic artery dissection.

BACKGROUND: We used an ultrasonic scalpel (USS) and an argon beam coagulator (ABC) to test their effectiveness and feasibility in comparison to conventional electrocautery for Internal Thoracic Artery (ITA) takedown, time for takedown, number of clips, thermal impact, along with morphological integrity assessed by histology. PATIENTS AND METHODS: Ninety-three patients undergoing elective coronary bypass surgery were prospectively randomized into three groups. In thirty-one patients, either an ultrasonic scalpel (USS, group A), an argon-beam coagulator (ABC, group B) or conventional electrocautery (CEC, group C) was used for ITA harvesting. RESULTS: Harvest times for ITA takedown using CEC (16.7 +/- 6 min) was significantly faster compared to ABC (21.6 +/- 8.1 min; p = 0.02) and USS (24.1 +/- 8.1 min; p < 0.001). There was no significant difference comparing harvest times of USS and ABC (p = 0.1). The number of hemostatic clips used was significantly lower when using USS (5.5 +/- 4.6 clips) compared to both CEC (16.6 +/- 6.2 clips; p < 0.001) and ABC (20.4 +/- 6.5 clips; p < 0.001) and significantly lower using CEC compared to ABC (p < 0.007). There were no significant differences in bleeding points within the tissue bed among the groups (ABC 11/31 patients, CEC 11/31 patients and USS 12/31 patients). CONCLUSION: This study demonstrates that dissection of the ITA pedicle can be safely done with USS, ABC, and CEC. However, USS is associated with less hemostatic clip demand but prolonged harvest time compared it to ABC and CEC; histological assessment revealed no significant difference when comparing groups and equipment used. A variety in design of the hooks may probably ease ultracision practicability.

Epicardial echocardiography for correct placement of the intracardial biventricular assist device (Impella).

BACKGROUND: Correct placement of the intracardial biventricular assist device (Impella) as a supporting system for off-pump coronary surgery is routinely checked by transesophageal echocardiography and invasive pressure measurements. However, it remains difficult to verify the accurate position of the right heart system when the posterior wall is exposed. METHODS: In 23 patients undergoing augmented beating heart CABG surgery, the correct placement of the lmpella-system was controlled by TEE as well as by a new 15-6 L epicardial echotransducer (EE) (Agilent, Andover, MA). RESULTS: TEE assisted well in inserting the system in all patients. The correct placement of the distal end of the right heart system 1.5 cm behind the pulmonary valve was verified in 18/23 cases by TEE vs. 23/23 cases by EE. Dislocation of the devices during tilting of the heart could only be verified by EE. CONCLUSIONS: Epicardial echocardiography is a useful, innovative method for monitoring the correct placement of the new intracardial biventricular assist device during beating-heart surgery.

A new intracardiac microaxial pump: first results of a multicenter study.

As coronary artery bypass grafting (CABG) surgery in the beating heart technique is progressing, new devices have been developed to overcome hemodynamic instabilities while tilting the heart for exposure of back wall vessels. A new device for in heart biventricular intracorporeal circulation was applied in 42 patients undergoing CABG surgery (Group 1). The control group consisted of 38 patients operated on using a conventional cardiopulmonary bypass setup (Group 2). The study protocol of the prospective, randomized multicenter study was approved by the local ethics committees. Patients were included following inclusion criteria and patient informed consent. Mean age, procedure time, mean arterial pressure (MAP), and hemolysis by means of plasma free hemoglobin (fHb) were assessed preoperatively, perioperatively, on postoperative Days 1 to 3, at discharge, and at a 3 month follow-up. The mean age was 62.1 (range 59-74) years (Group 1), 62.7 (range 48-72) years (Group 2); procedure time was 112 min +/- 31.9 min (Group 1), 137.4 min +/- 36.2 min (Group 2); and 2.3 +/- 0.6 (Group 1), 2.2 +/- 0.7 (Group 2), vessels were revascularized. The flow on pump was 3.7 (2.5/4.4) L/min (Group 1), 4.9 (3.6/6.2) L/min (Group 2) which resulted in a MAP of 69.8 (4.0/143) mm Hg (Group 1), 58.3 (5.3/94) mm Hg while assessing the vessels of the back wall. Hemolysis defined by fHB was lower than 20 mg/dl at all times pre- and postoperatively. Intraoperative maximum values were up to 100 mg/dl in 4 patients (2 in Group 1 and 2 in Group 2). Body mass index was 26.4 +/- 2.6 (Group 1), 27.9 +/- 3.2. New York Heart Association Class was II to III in both groups. There were no pump related life threatening or severe adverse events. Beating heart procedures with ICC can be reliably and safely achieved. As the device is easy to use, it may deserve a more widespread use in the future.

[Patient-adapted valve selection: biological vs. mechanical heart valve replacement in aortic valve diseases]. / Patientenadaptierte Klappenselektion: biologischer vs. mechanischer Herzklappenersatz bei Aortenklappenvitien.

Since the first aortic valve replacement performed by Harken in 1960, the operation of aortic valve disease by replacing the native valve with a heart valve prosthesis has become one of the most frequently performed procedures in cardiac surgery. For valve replacement there are biological (xenografts and homografts) and mechanical heart valve prostheses available. When choosing the most suitable prosthesis the limited durability of a biological prosthesis and the risks of lifelong anticoagulation for a mechanical prosthesis have to be balanced. In this article the indication for operation of aortic valve stenosis and aortic regurgitation are discussed first. Based on the literature of the last 2 years the advantages and disadvantages of mechanical and biological heart valve prostheses (xenograft, homograft and ROSS procedure) are discussed. In addition rarely used techniques like aortic valve reconstruction are presented. Due to the fact that a biological prosthesis has a durability of 12-15 years and the risk of bleeding complications under anticoagulation grows with increasing age, the choice of a biological prosthesis can be recommended from the age of 65 years. Results of long-term studies at to whether this limit can be diminished by using a stentless biological prosthesis have to be awaited.

[Patient adapted valve selection: biological vs. mechanical heart valve replacement in aortic valve diseases]. / Patientenadaptierte Klappenselektion: biologischer vs. mechanischer Herzklappenersatz bei Aortenklappenvitien.

Since the first aortic valve replacement performed by Harken in 1960, the operation of aortic valve disease by replacing the native valve with a heart valve prosthesis has become one of the most frequently performed procedures in cardiac surgery. For valve replacement there are biological (xenografts and homografts) and mechanical heart valve prostheses available. When choosing the most suitable prosthesis the limited durability of a biological prosthesis and the risks of lifelong anticoagulation for a mechanical prosthesis have to be balanced.In this article the indication for operation of aortic valve stenosis and aortic regurgitation are discussed first. Based on the literature of the last 2 years the advantages and disadvantages of mechanical and biological heart valve prostheses (xenograft, homograft and ROSS procedure) are discussed. In addition rarely used techniques like aortic valve reconstruction are presented.Due to the fact that a biological prosthesis has a durability of 12-15 years and the risk of bleeding complications under anticoagulation grows with increasing age, the choice of a biological prosthesis can be recommended from the age of 65 years. Results of long-term studies at to whether this limit can be diminished by using a stentless biological prosthesis have to be awaited.

Primary left-atrial leiomyosarcoma.

A patient rapidly developing right heart failure due to a left-atrial leiomyosarcoma was admitted for surgery. A large tumor, originating in the left atrium and extending into both pulmonary veins, was removed. Histology showed an unusual epitheloid appearance of many cells with occasional mitoses and a strong immunexpression to desmin and actin. Six months later heart failure developed again: computer tomography demonstrated regrowth of the tumor in the left atrium with invasion of the mediastinum and the para-aortal lymph nodes. The patient died shortly after.