Identifying the linear phase of the relativistic Kelvin-Helmholtz instability and measuring its growth rate via radiation.

For the relativistic Kelvin-Helmholtz instability (KHI), which occurs at shear interfaces between two plasma streams, we report results on the polarized radiation over all observation directions and frequencies emitted by the plasma electrons from ab initio kinetic simulations. We find the polarization of the radiation to provide a clear signature for distinguishing the linear phase of the KHI from its other phases. During the linear phase, we predict the growth rate of the KHI radiation power to match the growth rate of the KHI to a high degree. Our predictions are based on a model of the vortex dynamics, which describes the electron motion in the vicinity of the shear interface between the two streams. Albeit the complex and turbulent dynamics happening in the shear region, we find excellent agreement between our model and large-scale particle-in-cell simulations. Our findings pave the way for identifying the KHI linear regime and for measuring its growth rate in astrophysical jets observable on earth as well as in laboratory plasmas.

Minimally invasive coronary revascularization in elderly patients.

BACKGROUND: Internal mammary artery to left anterior descending coronary artery anastomosis can be done without extracorporeal circulation on the beating heart. This method seems to have particular advantages for elderly patients, those 70 years old or older. METHODS: From January 1, 1997, to October 31, 1997, 27 patients have been operated on with a minimally invasive approach through a left-sided minithoracotomy. Twelve patients had up to four previous percutaneous interventions with percutaneous transluminal coronary angioplasty (3) or percutaneous transluminal coronary angioplasty and stent implantation (9). The remainder showed stenosis not suitable for percutaneous transluminal coronary angioplasty or an occluded vessel. In all patients the internal mammary artery was anastomosed with the left anterior descending coronary artery, and in 2 patients additionally with the first diagonal. In 1 patient the operation had to be converted to a sternotomy because it was impossible to identify the left anterior descending coronary artery. RESULTS: All patients survived the operation. There was no perioperative infarction. All patients were extubated within 4 hours. Mean stay in the intensive care unit was 20.3 hours; postoperative stay was 7.4 days. Nine patients had elective repeat angiography within 10 days postoperatively and all showed a patent graft. CONCLUSIONS: We believe that minimally invasive coronary revascularization of the anterior wall can be done in elderly patients with low risk and good results.

Anabolic steroids (metenolone) improve muscle performance and hemodynamic characteristics in cardiomyoplasty.

The loss of force and mass in the conditioned latissimus dorsi muscle are principal reasons for the poor improvement in hemodynamic functioning attained by cardiomyoplasty. Using 24 sheep, we investigated the effect of anabolic steroids on the hemodynamic, histologic, and myophysiologic characteristics in the setting of cardiomyoplasty. In 12 of the animals (group A), the latissimus dorsi muscles were electrically conditioned with an Itrel pulse generator; in the remaining 12 animals (group B), the electrical conditioning was combined with the administration of an anabolic hormone (metenolone; 100 mg/week). The hemodynamic measurements were performed during isolated perfusion of the subclavian artery (maintenance of pressure in the muscles), while all other circulation variables were held at the exact and reproducible value of zero by inducing ventricular fibrillation. Maximum force and muscle mass showed a significant increase in group B (maximum force: group A, 4.23 +/- 0.55 kp, and group B, 6.0 +/- 3.14 kp; muscle mass: group A, +11.07% +/- 1.06%, and group B, +79.9% +/- 40.8%). The ratio of type I to type II fibers after 12 weeks was 65.2% to 34.8% in group A and 96.7% to 3.3% in group B, as opposed to 19.9% to 80.1% in the control group. No side effects of the anabolic steroids were observed during the experiment. In the hemodynamic studies, we were able to demonstrate a further significant increase in the left ventricular pressure, fractional fiber shortening value, ejection fraction, stroke volume, cardiac output, and stroke work when using conditioned latissimus dorsi muscles that were additionally treated with metenolone.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of an anabolic steroid (Metenolon) on contractile performance of the chronically stimulated latissimus dorsi in sheep.

In 12 sheep the left latissimus dorsi muscles (LD) were conditioned by chronic electrostimulation with a pulse generator (Itrel, Medtronic). Six animals (group B) received a weekly intramuscular injection of an anabolic steroid (Metenolon). After 14 weeks the contraction parameters of the left LDs (group A and B) and right LDs (control group) were investigated. The increase in weight of the conditioned LDs was 11.07% (+/- 1.06%) in group A and 79.97% (+/- 40.8; P < 0.05) in group B. The force capacity under stimulation patterns which were just tetanic was 1.15 kp in group A and 4.13 kp in group B (P < 0.05); under supramaximal stimulation patterns it was 4.23 kp (A) and 6.0 kp (B) (P = ns). The force time relation (dF/dt) was 6.7 kp/s for the left LDs in group A versus 16.4 kp/s for the right LDs (P < 0.01); in group B it was 5.13 kp/s for the left LDs versus 15.8 kp/s for the control muscles (P < 0.05). The maximal force (Fmax) per 100 g muscle weight did not differ significantly (A: 2.42 kp/100 g; B: 2.52 kp/100 g). In conclusion, the LD muscles which were subjected to both anabolic therapy and electrical stimulation showed a significant increase in their force capacity due to an enormous increase in mass. Fibre type transformation was complete only in group B. No fibre deterioration was observable in either group. No anabolic side effects were detected in the animals. With the use of anabolic steroids, therefore, a clearer direct increase in contractility on the left ventricle should be expected ("squeezing" theory), as well as a contribution to reduction in wall tension and myocardial oxygen consumption, respectively, according to Laplace's Law (via the considerable increase in thickness).

[The effect of timing of surgical intervention on fatality of acute endocarditis]. / Der Einfluss des Zeitpunktes der operativen Intervention auf die Letalität der akuten Endokarditis.

Between 1/1986 and 5/1992 a total of 5283 surgical procedures involving extracorporal circulation were performed at our clinic, including 44 patients who underwent a total of 54 operations for acute endocarditis. On the basis of a retrospective study, this paper presents the pre-operative findings and the results of surgery in relation to the duration of the case history. Pathogenic microorganisms were successfully grown from the blood cultures of 63.6% (n = 31) of the patients. Among these microorganisms were viridans streptococci (n = 12), coagulase-negative staphylococci (n = 5), staph. aureus (n = 5), beta-haemolytic streptococci (n = 2) as well as combined infections (n = 2) and miscellanea. Preoperatively, 38 patients were in NYHA stage III or IV. Surgery resulted in an average improvement of 1.6 NYHA classes from NYHA 3.3 to NYHA 1.7. The total-mortality rate was n = 13; early mortality was n = 3. The mean follow-up period was 3.9 years (minimum 5 weeks, maximum 6.4 years). The time elapsed between initial clinical manifestation of the disease and operation had a significant influence on mortality and on the prevalence of complications. Patients who died of endocarditis had a significantly longer case history (p < 0.05). The prognosis was poorer, according to our data, if the case history extended over more than 80 days. Our results demonstrate clearly the necessity for such patients to be referred to a heart surgeon without delay.

[The incidence of wound healing disorders in heart surgery]. / Häufigkeit von Wundheilungsstörungen in der Herzchirurgie.

In a five-year retrospective study we investigated the wound infection rate after median sternotomy in 2805 adult patients on whom elective surgery had been performed with extracorporeal circulation. On the basis of 14,700 apparently relevant data from 101 patients with wound healing disturbances at the sternotomy site, both the significance of predisposing risk profiles and the prevalence of nosocomial pathogens were evaluated. The control group was formed by 100 patients selected at random. The results were checked for statistical significance using the X2 test for alternative characters; the significance level was set at alpha = 5%. The infection rate observed in our group was 3.6%, which was assigned to 5 internally defined degrees of severity. Cases of healing by second intention were caused to 93% by coagulase-negative staphylococci and staphylococcus aureus. Factors leading to a decrease in oxygenation of the wound area (low-output syndrome, rethoracotomy), diabetes, obesity and the duration of wound drainage were accompanied by a significantly more frequent occurrence of wound healing disturbances. On the other hand, perfusion-technical parameters, operation duration, revascularisation techniques (IMA/ACVB), pulmonary conditioned hypoxemias and the end-of-year desinfection usual in our clinic had no influence on wound healing. Seasonal fluctuation of the epidermal microclimate appear to be responsible for the prevalence and virulence of the pathogen strains in the clinic environment. The preventive measures used in cardiosurgical clinics do not yet represent a fully developed prophylaxis against exposure to nosocomial pathogens.

[Heart surgery interventions in patients with terminal renal failure]. / Herzchirurgische Eingriffe bei Patienten mit terminaler Niereninsuffizienz.

It is reported on first own experiences in the cardiosurgical treatment of patients with terminal renal insufficiency. Frequency of cardiovascular complications and their high lethality in this group of disease force into early and routine use of cardiological diagnostics and cardiosurgical therapy. The surgical indication should exclusively be based on the severity of the present heart disease. The permanent dialysis treatment is no contraindication. When the patients are carefully selected and with close cooperation of all specialties participating the operative risk of patients with terminal renal insufficiency does not essentially differ from that one of patients with healthy kidneys.

[Abdominal complications following heart surgery using the heart-lung machine]. / Abdominale Komplikationen nach herzchirurgischen Eingriffen mit der Herz-Lungen-Maschine.

Reported in this paper are 17 abdominal complications among 2,161 patients, following cardiac surgery, using cardiopulmonary bypass. This incidence is comparatively low, accounting for only 0.78 percent, whereas figures between 0.3 and 1.6 percent have been reported in the international literature. Lethality worldwide has been quoted to be between 25 and 50 percent and amounted to 23.5 percent for the above patients. This seems to underscore the great importance of early decision-making on appropriate therapy. Haemorrhage from the upper gastro-intestinal tract due to stress-related ulcers had been the predominant finding in this study. Acute pancreatitis developed in two patient, one of them ending in death. Acute cholecystitis and ischaemic colonic gangrene were additional complications. No significant extension of perfusion periods was established, which was in deviation from findings made by other authors.

[Arteriovenous fistula in the tabatière region--primary shunt in chronic hemodialysis]. / Die arteriovenöse Fistel in der Tabatiere--der Primärshunt zur chronischen Hämodialyse.

The number of patients with end-stage renal disease treated by chronic hemodialysis is permanently increased. An assumption of a long-term and successful treatment is the durable functioning vascular access. The method of choice worldwide is the typical Cimino fistula on the distal forearm, but a more peripheral arterio-venous fistula is possible. A fistula in the Tabatière region has proved to be excellent in our experience with 51 patients operated between January 1985 and March 1987. The surgical technique, results, and advantages of this vascular access operation are described.

[Arterial reconstructions spanning the knee joint]. / Kniegelenküberschreitende arterielle Rekonstruktionen.

Knee-joint crossing arterial repair is an alternative solution for patients whose extremities otherwise might have to be amputated. Indications are according to Fontaine for Stages III and IV. Specialised angiographic preparatory examination and knowledge of microsurgical techniques are required. Reference is made to peculiarities of surgical access routes, vascular substitute materials, and specific surgical techniques. The use of this approach to peripheral vascular repair appears to be justified against the background of international achievements and the authors' own results.

[Peripheral venous pressure in acute and chronic femoral-pelvic vein occlusion--an experimental study]. / Der periphere Venendruck beim akuten und chronischen Bein-Beckenvenenverschluss--eine experimentelle Studie.

The behaviour of the peripheral venous pressure was checked after starvation of the venous main vessel of the pelvic limb in 34 mongrel dogs in long-term course about 40 weeks. The influence of recanalisation processes on the pressure development was excluded by the ligature model. The pressure measurements took place continuously statically and dynamically in horizontal and in oblique posture. They produced a changed pressure characteristic with a chronically increased resting pressure and a decreased drop in pressure with load. The insufficient transport capacity of the spontaneously originated collateral circulation could be pointed out.

[Surgery of leg and pelvic venous thrombosis]. / Die chirurgische Therapie der Bein- und Beckenvenenthrombose. Operative Möglichkeiten und Ergebnisse.

33 patients suffering from crural-pelvic venous thrombosis and having been treated surgically were now followed-up. The late results obtained were satisfactory.

[Transluminal angioplasty in combination with surgical procedures in arteriosclerotic occlusive disease of the lower extremity (author's transl)]. / Die Kombinationstherapie arteriosklerotischer Durchblutungsstörungen der unteren Extremität--perkutane transluminale Angioplastik und chirugische Revaskularisation.

In 16 patients suffering from occlusions of the pelvic and/or femoral arteries a combined treatment was performed: percutaneous transluminal angioplasty (PTA) and surgical reconstructive measures. Indications for this procedure are: 1. Stenoses of the pelvic arteries and occlusion of the ipsilateral superficial femoral artery with PTA for the iliac artery and endarterectomy for the femoral artery. 2. Occlusion of the iliac and the femoral arteries with a decreased run-off: PTA and lumbar sympathectomy. 3. Endarterectomy on one side and PTA contralaterally.

[Differential diagnosis of acute leg swelling (author's transl)]. / Ein Betrag zur Differentialdiagnose akuter Beinschwellungen.

Reference is made to aspects relating to the aetiology of acute leg swelling following surgical or radiological treatment of uterine and ovarian tumours. Four cases are reported, in that context. The swellings described developed up to ten years after initial therapy. Differential diagnosis and therapeutic approaches are discussed. The need for early cooperation between the gynaecologist, radiologist, angiologist, and vascular surgeon is underlined.

[Shunting procedures in portal hypertension in children (author's transl)]. / Erfahrungen mit drucksenkenden Anastomosenoperationen bei portaler Hypertension im Kindesalter.

31 children aged 2,5 to 14 years suffering from portal hypertension underwent shunting operations (cavosplenal and cavomesenteric anastomoses). The follow-up period covers 2 months to 8 years. Patent anastomoses could be demonstrated in 26 patients.

[Surgical treatment of segmental occlusions of the popliteal and the crural arteries with modified vascular prostheses (author's transl)]. / Die operative Behandlung von Segmentverschlüssen der A. poplitea und kruraler Arterien unter Verwendung verschiedener Gefässersatzmaterialien.

Possibilities and indications for reconstruction of the femoro-popliteal and femoro-crural region are dealth with. Autogenous veins still are the favoured graft material for the femoro-popliteal/crural bypass. If an autogenous vein is not available bovine arterial grafts, Gore-Tex-PTFE prostheses or modified human umbilical cord vein are alternative materials.