PubMed Health⌕ Search

Biomedical subjects

H Wiksell

Publications and source records attributed to H Wiksell.

12 recordsLinked to original sources
PubMed2002

Long-term clinical outcome of transurethral microwave thermotherapy (TUMT) 1991-1999 at Karolinska Hospital, Sweden.

OBJECTIVE: Minimal invasive methods, such as transurethral microwave thermotherapy (TUMT), are economical and have modest side effects compared with transurethral electro-resection of the prostate (TUR-P). The treatment results from different TUMT-systems vary. Follow-up studies on each system type are therefore necessary. The objectives of this study are to summon the long-term clinical results of our TUMT-system and search for a pre-treatment parameter that can measure responding patients. MATERIAL AND METHODS: Three hundred and seventy-one patients with benign prostate hyperplasia (BPH) were treated with TUMT at Karolinska Hospital, Sweden with the ECP-system (Comair AB, Stockholm), for 30 or 60 min. They were followed up 12 to 72 months after TUMT. RESULTS: At follow up approximately 76% subjectively judged that they had benefited from the treatment and 22% judged that they were fully cured. The over-all IPSS and Quality of Life score decreased approximately 40% and 30% respectively. Forty-one per cent of the patients with CAD (cathéter à demeure) before the treatment became permanently or temporarily catheter-free after the treatment. Q(max) increased 21% and 11% after 1 and 6 months respectively. Q(max) ranging from over 10 ml/s seem to be a selection parameter that increases the number of responding patients. CONCLUSION: These long-term clinical data show that TUMT treatment with ECP (electro-coagulation, prostate), gives a good success-rate, with reduction of symptoms. Furthermore there is a good chance of becoming catheter-free after TUMT.

Aged↗
PubMed2001

Cellular effects of high-intensity focused continuous wave ultrasound alone and in combination with X-rays.

PURPOSE: To investigate the cellular effects of 1.1 MHz high-intensity focused continuous wave (CW) ultrasound alone and in combination with X-rays. MATERIALS AND METHODS: V79 cells were exposed to ultrasound of different intensities for 30s (non-hyperthermic conditions). In the combined treatments, cells were exposed to ultrasound (63 W/cm2) either before or after 2 Gy X-irradiation. Cellular effects studied were clonogenic survival, DNA strand breaks (pulsed-field gel electrophoresis, DNA precipitation assay) and membrane integrity (morphological analysis). RESULTS: With increasing ultrasound intensity, cell survival decreased in a dose-dependent manner as the induction of DNA strand breaks, the fraction of cells with lost membrane integrity and cell lysis increased. In the treatments with combined exposures, the regimen with X-rays before ultrasound had a nearly additive effect on cell kill, whereas the reverse regimen with ultrasound exposure before X-irradiation resulted in a synergistic effect (p<0.012). CONCLUSIONS: High-intensity focused CW ultrasound induces an intensity-dependent reduction in clonogenic survival in V79 cells, which seems to depend on both DNA and membrane damage. Combined exposures of ultrasound and X-rays resulted in a synergistic reduction in cell survival when cells were exposed to ultrasound before X-rays but not for the reverse regimen. Thus, a larger fraction of the repairable sublethal cell damage induced by an initial ultrasound exposure was rendered non-repairable by a subsequent X-ray exposure than if the reverse treatment order was used.

Animals↗
PubMed2000

Miniaturised ultrasonic aspiration handpiece for increased applicability.

OBJECTIVE: At present, ultrasonic aspiration is routinely used in several fields of surgery, especially in brain and spinal micro-surgery for tumour removal. In order to broaden the access to difficult surgical sites, it is important to design highly miniaturised but still efficient handpieces. The internal resonant system, always made of high-grade materials, must be optimally dimensioned. Normally this is done semi-empirically, by successively improving the design during many iterative test steps. This method however involves several additional difficulties when the degree of miniaturisation increases. For example, small transducer weights exacerbate heat-dissipation problems and make design optimisation important. METHODS: To resolve these problems we have produced modelling software that makes it possible to simulate and automatically tune each individual interacting section of the design before it is actually manufactured, thereby assuring optimal efficiency. RESULTS: Using a new mini-handpiece, designed via the software, two cases of dissection of acoustic neurinomas were successfully performed. CONCLUSION: Using conventional physical steps for improving ultrasonic aspiration handpieces, several problems arise when the grade of miniaturisation increases, due to increasing demands. We have designed computer software for handpiece simulation. Using this model it has been possible to manufacture a highly efficient miniaturised handpiece.

Equipment Design↗
PubMed1999

The impact of the geometry of the lithotriptor aperture on fragmentation effect at extracorporeal shock wave lithotripsy treatment.

The aim of this study was to determine the impact of the aperture size of an electro-hydraulic lithotriptor on the fragmentation effect. We also wanted to investigate whether a potential change in the capacitance of the pulse forming network (PFN), at a certain energy level, might have an impact on fragmentation rate. Two different apertures with a diameter of 23 and 17 cm respectively were compared using two different values of total PFN capacitance: 50 nF and 80 nF. Model stones of similar size and weight were fragmented. The number of shots for complete fragmentation or the grade of fragmentation after a certain number of shots was measured. This study shows that for the shock wave system used, the 23-cm aperture seems to provide more effective fragmentation as function of the number of shots compared with the 17-cm aperture at the same energy level. Furthermore, a minor change in the PFN capacitance between reasonable limits does not affect the fragmentation efficiency. This article also highlights the fact that it is not relevant simply to compare the voltage level given in the shots in extracorporeal shock wave lithotripsy treatment between different lithotriptors.

Electric Conductivity↗
PubMed1999

Sham treatment compared with 30 or 60 min of thermotherapy for benign prostatic hyperplasia: a randomized study.

OBJECTIVE: To study the differences in subjective and objective results after 30 or 60 min of transurethral thermotherapy (TUMT) or sham treatment in men with benign prostatic hyperplasia (BPH). PATIENTS AND METHODS: Forty-four patients with lower urinary tract symptoms caused by BPH were randomized to undergo 30 or 60 min of TUMT or sham treatment (14, 16 and 14 patients, respectively). The patients were evaluated using symptom scores, timed micturition, free flow rates and urodynamics before and after treatment. They were followed for 1 year, at the end of which they rated the treatment results on a self-administered visual analogue scale. RESULTS: Forty-two patients completed the study. The treatment failed in some patients in all groups, but the improvement in maximum and median flow rates, timed micturition and micturition frequency (day and night) was greater after TUMT than in the sham-treated group. Symptom scores also improved more after TUMT, although not significantly. There was a good correlation between the decrease in urinary frequency, especially nocturnal, and the patients' perception of a successful treatment, whereas the increase in maximum urinary flow rate was apparently of little importance. CONCLUSIONS: TUMT had a better effect than the placebo treatment, having a greater impact on irritative than on obstructive symptoms. More patients were satisfied after the 30-min than after the 60-min treatment.

Aged↗
PubMed1999

Effect of externally applied focused acoustic energy on clot disruption in vitro.

Application of low-frequency ultrasound for clot disruption has been suggested as a potential therapy to enhance thrombus dissolution, but the optimal mode for delivery of ultrasound with clot-disruptive properties has not yet been extensively explored. Target-specific effects are desirable and may be accomplished by focusing the ultrasound. Adequate focusing, however, requires a short wavelength. The aim of this study was to compare the clot-disruptive effects of different modalities of focused acoustic energy. An in vitro model (10 blood clots for each modality) was used to test the clot-disruptive capacity of (i) shock waves generated in an electrohydraulic lithotriptor; (ii) focused continuous ultrasound of frequency 1.1 MHz, delivered from a specially constructed piezoelectric transducer; and (iii) focused pulse-modulated ultrasound of frequency 1.1 MHz delivered from the same transducer. Exposure to 30 s of focused pulse-modulated ultrasound caused a marked reduction (99+/-2%) in clot weight compared with 30 shock waves (11+/-5%) or 30 s exposure to focused continuous wave ultrasound (11+/-6%) (P<0.0001). The observed marked and rapid disruptive effect on blood clots of focused high-frequency ultrasound indicates an alternative approach for external ultrasound-mediated thrombus destruction in vivo. The focused pulse-modulated technique has potential to exhibit the desired effect in a well-defined target volume and provides the means for control of the average power.

Humans↗
PubMed1995

Implications of cavitation phenomena for shot intervals in extracorporeal shock wave lithotripsy.

OBJECTIVE: To study the influence of shot intervals and the quality of the coupling medium (degassed water) in extracorporeal shock wave lithotripsy (ESWL). MATERIALS AND METHODS: Acoustic scattering and damping (and thereby also the focal size) were modelled with respect to the conditions of the coupling medium, using continuous wave high intensity ultrasound. The influence of the shot interval on rise time and attained shock wave pressure were quantified with a modified ESWL apparatus and a specially designed hydrophone. RESULTS: In tap water, which has a high content of dissolved gases, the focus produced was bulb-shaped, with a diameter of approximately 4 cm, whereas degassed water gave a small focus that produced a water jet only a few millimetres in diameter. The efficacy of the acoustic energy decreased with shot intervals shorter than 1.2s. Longer pauses resulted only in prolonged treatment times. CONCLUSION: ESWL becomes inefficient if the intervals between pulses are too short, particularly when ECG R-wave triggered pulses are used on patients with tachycardia. The gas content of the coupling medium is also important for successful ESWL. The efficacy of the system used for degassing the water should be checked at regular intervals.

Lithotripsy↗
PubMed1990

Liver resection with the Sonocut ultrasonic knife.

Previous reports and our findings suggest that resection by ultrasound is of appreciable merit in liver surgery. Blood can be saved and bile leakage diminished as the larger vessels and bile ducts can be skeletonized unharmed, whereas the dissector selectively carries away the parenchyma. Otherwise virtually inaccessible tumours can be approached. The ultrasonic dissector/aspirator does not harm the tissue in depth beyond the resection surface and thus not much devitalized tissue is left in the wound.

Animals↗