Helmut Weber

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Subarachnoid cisterns and their contents are described briefly in the light of observations made during microsurgical explorations. The concept of intracranial surgery in terms of moving from one cistern to another is presented here with particular emphasis on the cisterns in surgical approaches to intracranial vessels and nerves for the treatment of(More)
A simple but efficient method to obtain accurate solutions of a system of nonlinear equations with a singular Jacobian at the solution is presented. This is achieved by enlarging the system to a higher dimensional one whose solution in question is isolated. Thus it can be computed e. g. by Newton's method, which is locally at least quadratically convergent(More)
In vitro porcine arteries and veins have been welded end-to-end using either a 808 nm diode laser combined with an indocyanine green enhanced albumin solder, or with a continuous-wave (cw) Ho:YAG laser without biological solder. The vascular stumps were approached to each other over a coronary dilatation catheter in order to obtain a precise alignment and(More)
Since 1992 a small air-cooled opthalmological argon laser (Augus system, 3 W max.) equipped with a fiberoptic microhandpiece has been used for stapedotomy at the Inselspital, Berne. The microhandpiece has been developed especially for otological purposes in our electronic laboratory. In order to measure the effect of argon laser pulses applied through the(More)
Intramural temperatures were monitored during catheter-directed endomyocardial non-contact laser irradiation by means of an array of thermocouples inserted epicardially. Via a novel electrode-laser catheter, a total of 30 Nd-YAG laser pulses, 1064 nm, 25 W/15 s, 20 W/30 s, 15 W/45 s,n = 10 each, were aimed at various endocardial sites in the ventricles of(More)
BACKGROUND Growth and sizes of lesions produced during catheter ablation is difficult to control. Laser lesion formation was evaluated during various flow rates and energy settings by using an open-irrigated laser catheter on a thigh-muscle dog model. METHODS Laser radiation at 15 W or 20 W was applied in blood for 10 seconds, 20 seconds, 30 seconds, 40(More)
AIMS To evaluate laser lesion formation in the beating hearts of dogs by using an open-irrigated electrode-laser mapping and ablation heart catheter. METHODS AND RESULTS A total of 50 laser applications at 15 W (n = 31) and 20 W (n = 19) for 10-50 s, with an irrigation flow of 35 mL/min were aimed at the right (n = 15) and left (n = 9) atrial, right (n =(More)
Nd-YAG laser photocoagulation is a successful technique for the intraoperative treatment of arrhythmia. Experimental endocardial transcatheter laser application, however, occasionally causes tissue vaporization and perforation. Intramural heat generation was simulated in a Monte Carlo model as a function of laser beam profile and divergence versus(More)
Microiontophoretic techniques were used to examine the changes in activity of inner hair cell afferents in the guinea pig following circumscribed penetration of cochlear bone with erbium:YSGG laser pulses. Neuronal responses to the application of the glutamate agonists N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid(More)
AIMS To assess the laser effects on the conduction system in dog hearts by monitoring potential amplitudes (PA) in the focused local electrograms (LEG) recorded via pin electrodes (PEs) from the tip of an open-irrigated electrode-laser mapping and ablation (ELMA) catheter. METHODS AND RESULTS A total of 54 mapping guided laser impacts (continuous wave(More)