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Biomedical subjects

T Walther

Publications and source records attributed to T Walther.

At least 109 records · Page 6Linked to original sources
PubMed1999

Are dermatologists in private practice interested in teledermatological services?

Diagnosing dermatologic skin conditions can be difficult, especially in pigmented skin lesions. Therefore, the consultation of an expert via teledermatology could prove vital. For this purpose, a rapid transfer of medical data including high resolution images is essential. This transfer can be performed with a variety of modern telecommunication technologies, including ISDN, highspeed-ISDN, Internet, and Intranet. As the levels of both communication software and camera-systems can be quite different, our survey investigated the equipment of 84 dermatologists in private practice. A questionnaire was distributed on computer equipment, operating system software, and any image documentation systems used, as well as required telecommunications equipment and possible applications of tele-dermatology. This survey showed a response rate of 54% and proves that dermatologists in private practice are interested in telemedicine services. Most dermatologists surveyed use Windows 95 operating software and 74% have access to modern ISDN modems or PC-cards. Dermatologists currently prefer applications with low-tech communication hardware and software requirements. Consultation of dermatological centers was the favored application with 59%. Our survey clearly demonstrates that a high percentage of dermatologists in private practice would use tele-dermatology. In our experience, for the excellence of this service an image documentation system is essential to provide the tele-dermatological expert with standardized images with constant illumination.

Dermatology↗
PubMed1999

Endoscopic coronary artery bypass grafting on the beating heart using a computer enhanced telemanipulation system.

OBJECTIVE: To develop a technique for computer enhanced endoscopic arterial bypass grafting on the beating heart in an experimental canine model. METHODS: Mongrel dogs (30-35 kg) were used. After single lung ventilation of the right lung was initiated the dogs were placed to the right. The videoscope and the end-effectors of the da Vinci telemanipulation system (Intuitive Surgical, Mountain View, CA) were introduced through three ports. Surgery was performed remotely from the console (motion scaling 3:1). After harvesting of the internal thoracic artery (ITA) and preparation of its distal end, the Endostab, a newly developed endoscopic stabilizer, was introduced through an additional port. The anterior wall of the heart was stabilized and the collateral branch (RC) of the left anterior descending artery (LAD) was ligated proximally and distally. The arteriotomy was made and the ITA-graft anastomosed to the RC. The animals were sacrificed and the grafts were checked for patency using bench angiography. RESULTS: In two of five dogs total endoscopic beating heart bypass grafting, including ITA harvest, stabilization, arteriotomy and performance of the anastomosis, was successfully performed using computer enhanced technology and a new endoscopic stabilizer. In two dogs the procedure was completed with femoro-femoral cardiopulmonary bypass (CPB) support on the beating or fibrillating heart, respectively. One dog expired due to VT. Hemodynamically, endoscopic stabilization was well tolerated. All four grafts were patent despite a target vessel diameter of less than 1 mm. CONCLUSION: The endoscopic stabilizer can sufficiently immobilize the heart to enable endoscopic beating heart coronary artery bypass grafting by means of a computer controlled instrumentation system.

Animals↗
PubMed1999

Comparison of MIDCAP versus conventional CABG surgery regarding pain and quality of life.

BACKGROUND: This prospective clinical trial focuses on pain and quality of life (QOL) after minimally invasive direct coronary artery bypass (MIDCAB) grafting versus conventional coronary artery bypass grafting (CABG). METHODS: Group A consisted of 65 consecutive MIDCAB patients using an anterolateral mini-thoracotomy and the "off-pump" technique. Group B consisted of 95 computer-matched patients who underwent conventional CABG with cardiopulmonary bypass (CPB). Pain was graduated using the visual analog scale (VAS), and the verbal rating scale (VRS) [Troidl 1990]. QOL was evaluated at the time of discharge and three months after surgery using modified Nottingham Health Questionnaires that separate physical, social, activity, emotional, pain, and sleeping conditions. RESULTS: Postoperative pain was higher after MIDCAB on postoperative day (POD) 1 (p< 0.002). From POD 4 onwards MIDCAB patients had less pain compared with the conventional group (p<0.04). MIDCAB patients required less pain medication from POD 4 onwards (p<0.05). QOL was significantly better in the MIDCAB group on POD 7 for physical (p< 0.038), activity (p< 0.016), pain (p< 0.041), and sleep (p<0.038) conditions. The three-month questionnaire showed significantly better levels for MIDCAB patients regarding physical (p< 0.03) and pain (p< 0.001) conditions, and a trend for activity (p< 0.08) and emotional (p<0.08) conditions. CONCLUSION: Compared to patients undergoing conventional surgery, MIDCAB patients suffer more pain in the first three postoperative days, probably as a result of the lateral thoracotomy. From POD 4 onwards, MIDCAB patients are significantly better, experiencing less pain and showing better physical, activity, and sleeping conditions even three months after surgery. This can be attributed to the absence of median sternotomy and/or the avoidance of cardiopulmonary bypass.

Aged↗
PubMed1998

[Sebaceous gland hyperplasia as a side effect of cyclosporin A. Treatment with the CO2 laser].

HISTORY AND CLINICAL FINDINGS: After renal transplantation 11 years previously followed by immunosuppression with cyclosporin A, a 59-year-old man developed, shortly after starting the medication, skin-coloured nodules in the region of both ears and the forehead. In the subsequent years the skin changes spread throughout the entire face. The nodes (up to 2 cm in diameter) and nodules were soft and yellowish-white in colour. In addition there were numerous distinct telangiectasias over the whole face. INVESTIGATIONS: Several skin biopsies were taken. They showed largely unremarkable epidermis but marked enlargement and multiplication of the sebaceous glands. DIAGNOSIS, TREATMENT AND COURSE: In view of the histological findings the diagnosis of sebaceous hyperplasia was established. After a trial with carbon dioxide laser, treatment over the entire surface of the two auricles was undertaken under full anaesthesia. The normal auricular contour was reconstituted by removal of the papules and nodes, without any scar formation. CONCLUSION: In the absence of an alternative medication and if the very marked skin changes show no sign of regression, "shaving off" by scalpel of the nodes and nodules or conventional surgery has been the available treatment. However, removal by carbon dioxide laser has the advantage of fewer side effect, is less stressful to the patient and provides a dry operative field.

Biopsy↗
PubMed1998

Sustained long term potentiation and anxiety in mice lacking the Mas protooncogene.

The Mas protooncogene is a maternally imprinted gene encoding an orphan G protein-coupled receptor expressed mainly in forebrain and testis. Here, we provide evidence for a function of Mas in the central nervous system. Targeted disruption of the Mas protooncogene leads to an increased durability of long term potentiation in the dentate gyrus, without affecting hippocampal morphology, basal synaptic transmission, and presynaptic function. In addition, Mas-/- mice show alterations in the onset of depotentiation. The permissive influence of Mas ablation on hippocampal synaptic plasticity is paralleled by behavioral changes. While spatial learning in the Morris water maze is not significantly influenced, Mas-deficient animals display an increased anxiety as assessed in the elevated-plus maze. Thus, Mas is an important modulating factor in the electrophysiology of the hippocampus and is involved in behavioral pathways in the adult brain.

Animals↗
PubMed1998

Leg telangiectasia treatment with a 1.5 ms pulsed dye laser, ice cube cooling of the skin and 595 vs 600 nm: preliminary results.

BACKGROUND AND OBJECTIVE: Preliminary results indicate that pulsed dye lasers (PDL) with 1.5 ms pulsewidth and 595 nm wavelength are effective in the treatment of leg telangiectasia. The aim of this study was to evaluate if the clinical results could be improved by a) an effective skin cooling with ice cubes and b) the longer wavelength of 600 nm. STUDY DESIGN/MATERIALS AND METHODS: In 87 patients with vessels up to 1 mm in diameter, 257 single test treatments were performed using wavelengths of 595 and 600 nm, fluences of 16, 18, and 20 J/cm2, a 1.5 ms pulse duration, and an elliptical spot of 2 x 7 mm. In 7 patients, the skin surface temperature curve was measured after cooling with ice cubes vs hydrogel dressings, and spot geometry and fluence were investigated with and without the gel dressing. RESULTS: Vessel clearance was evaluated 6-8 weeks after treatment. 20 J/cm2 were most effective (80% clearance >50%), and 18 J/cm2 were more effective than 16 J/cm2 (66.2 vs 52.5% clearance >50%). There was a tendency towards better results with 595 nm, but the differences were not significant. Vessels with a diameter <0.5 mm cleared significantly better than those with 0.5-1 mm (69.1 vs 31.9% clearance >50%). Hypo- and hyperpigmentation were seen in 32% of the patients. Cooling with ice cubes proved to be far more effective than with hydrogel dressings (temperature decrease approx 15 vs 5 degrees C). Additionally, the gel dressing caused an energy loss of approx 35% and an irregular spot geometry as shown on burn paper. CONCLUSIONS: Treatment of leg telangiectasia with the 1.5 ms-PDL is safe and effective, especially in vessels smaller than 0.5 mm in diameter; 595 nm and 18 J/cm2 seem to be somewhat more effective as 600 nm and 16 J/cm2; and 20 J/cm2 are even more effective, but persistent hyperpigmentation cannot yet be excluded due to insufficient follow-up time. Cooling with ice cubes is more effective and less expensive than gel dressings, and the short term clinical results are equivalent, even if the frequency of transient pigmentary changes is increased.

Bandages↗
PubMed1998

[Treatment of superficial varicosities with a flashlamp-pumped pulsed dye laser with 1.5 ms impulse time].

A new flashlamp-pumped pulsed dye laser with 1.5 ms pulse length and tunable wavelengths between 585 and 600 nm (Candela ScleroPLUS) is now available for the treatment of ectatic leg veins. We evaluated 232 single test treatments using 595 and 600 nm wavelength in 75 test persons. For smaller vessels up to a diameter of 0.5 mm, treatments at 16 and 18 J/cm2 showed good results in 60 and 82% respectively; for vessels up to 1 mm in 27 and 33%. Treatment at 595 nm was a little more effective than at 600 nm. Larger vessels could not be treated effectively. The main side effects consisted in hyper-(34%) or hypopigmentation (30%). Thus, in addition to the usual sclerotherapy, this laser is a useful device for the treatment of leg vein ectasia.

Adult↗
PubMed1998

DNA analysis for phospholipase A2 coding sequences of Mycoplasma hominis isolated from women with a normal pregnancy and women with a pregnancy complicated by preterm labour.

A possible cause of preterm labour is an increased synthesis of prostaglandins by a phospholipase A2 (PLA2) activity. PLA2 activity has been detected in Mycoplasma hominis. The aim of this study was to test whether chromosomal DNA of M. hominis contains sequences coding for PLA2. M. hominis was cultured in specimens from 5 women with normal pregnancy and 4 in preterm labour. Using sequence alignment, primer pairs for the active part of PLA2 of different species were designed for PCR analysis. No sequences coding for PLA2 could be amplified. Whatever its role in preterm labour, M. hominis is not involved in causing an increase of prostaglandin synthesis.

DNA, Bacterial↗
PubMed1998

Control of endoaortic clamp position during Port-Access mitral valve operations using transcranial Doppler echography.

The technique of computer-aided transcranial Doppler echography for continuous control of cerebral perfusion during minimally invasive mitral valve operations using the Port-Access system is described. Temporary displacement of the endoclamp in the aortic arch (brachiocephalic trunk, left carotid artery) is followed by cerebral embolic signals and a sudden decrease in the blood flow velocity in the middle cerebral arteries.

Aorta↗
PubMed1998

Minimally invasive coronary artery bypass grafting without cardiopulmonary bypass: early experience and follow-up.

BACKGROUND: There is renewed interest in coronary artery bypass grafting without cardiopulmonary bypass using the anterolateral minithoracotomy approach. We evaluated 209 patients who underwent minimally invasive direct coronary artery bypass grafting using an anterolateral minithoracotomy. The anastomosis was performed under direct vision on the beating heart without using cardiopulmonary bypass. METHODS: The procedure was performed using a 6- to 9-cm left (or right) anterolateral thoracotomy for internal thoracic artery graft harvesting and anastomosis. Different devices were used for local immobilization. In 195 patients a single internal thoracic artery to left anterior descending coronary artery bypass was performed, in 3 patients a single right internal thoracic artery to right coronary artery bypass, and in 11 patients the radial artery was used together with the internal thoracic artery as a T-graft. RESULTS: Conversion to sternotomy or cardiopulmonary bypass was necessary in 10 (4.7%) patients. Intraoperative myocardial infarction was observed in 4 patients (1.9%). Early postoperative redo operation was necessary in 5 patients (2.4%). Mortality was 0.47%. Postoperatively, 191 patients (91.3%) underwent angiography for graft patency control. The overall patency rate was 97.3%. Minor stenosis of the internal thoracic artery graft was observed in 18 patients (9.4%); moderate stenosis was observed in 5 patients (2.6%). Midterm angiographic follow-up after 6 months was performed in 58 patients. The patency rate was 98.2%. One patient with severe symptomatic stenosis (1.7%) underwent reoperation. CONCLUSIONS: With the help of the local immobilization systems off-pump coronary artery bypass grafting was safely performed through a minithoracotomy. The incidence of intraoperative and postoperative complications was low and follow-up showed good results. Thus, minimally invasive direct coronary artery bypass grafting is an excellent technique for arterial revascularization in patients having symptomatic left anterior descending coronary artery disease.

Adult↗
PubMed1998

Comparison of different anticalcification treatments for stentless bioprostheses.

BACKGROUND: New anticalcificant treatments have been developed because tissue calcification is a major contributing factor for bioprosthetic valve failure. METHODS: Aortic valve leaflet and aortic root tissue samples from stentless bioprostheses treated with No-React (Biocor, Belo Horizonte, Brazil), AOA (Medtronic freestyle, Minneapolis, MN), and BiLinx (St. Jude Medical, St. Paul, MN) were compared to a control group by subcutaneous implantation in 60 male weanling Sprague-Dawley rats. RESULTS: Calcium levels were in the range of 0.3 to 2.2 mg/g dry tissue at 3 and 12 weeks in all three treated aortic valve leaflet implants. The BiLinx treatment proved anticalcificant effectiveness on aortic root samples as well. There were statistically significant differences for valve leaflet tissue samples: No-React = AOA < BiLinx < < Control and for aortic root tissue samples: BiLinx < < AOA < Control = No-React. CONCLUSION: Calcification of aortic valve leaflets was significantly reduced by all new anticalcificant treatments. Inhibition of cellular calcification (BiLinx) resulted in additional reduction of aortic root calcification. Maximum anticalcificant properties upon both leaflet and aortic root is important as these are considered a functional unit in stentless bioprostheses.

Aluminum↗
PubMed1998

Minimally invasive port-access mitral valve surgery.

OBJECTIVES: This study evaluates the feasibility of video-assisted minimally invasive mitral valve surgery by means of the Port-Access system. The aim of the study was to minimize surgical access and to develop a video-assisted surgical technique. METHODS: The Port-Access system allows for closed chest endoluminal aortic clamping, cardioplegic arrest, and decompression of the heart. The mitral valve was either repaired (n = 28) or replaced (n = 23) in 51 patients by means of a minimally invasive approach through a right lateral minithoracotomy and under videoscopic guidance. RESULTS: Mean length of incision was 5.4 +/- 1.8 cm (range 3.8 to 8 cm). Mean duration of operation, cardiopulmonary bypass, and crossclamp time was 196 +/- 53, 133 +/- 52, and 72 +/- 27 minutes, respectively. Median intubation time was 25.5 hours (range 5 to 264 hours). Median duration of intensive care and hospital stay was 2 days (range 1 to 36 days) and 13 days (10 to 36 days), respectively. Hospital mortality was 9.8% (5/51). Overall morbidity was relatively high. In two patients acute retrograde aortic dissection led to conversion of the procedure. At follow-up (261 +/- 13 days), three patients required reoperation for paravalvular leakage. Baseline mean Duke activity index score was 19.3 +/- 11.3 before the operation and increased to 23.2 +/- 10 at 6 weeks' and 24.2 +/- 10.3 at 12 weeks' follow-up, respectively. CONCLUSION: The Port-Access system allows for video-assisted minimally invasive replacement and complex repair of the mitral valve through a right lateral minithoracotomy. However, morbidity and mortality associated with this novel technique were high.

Aged↗
PubMed1998

Less-invasive coronary artery bypass grafting: different techniques and approaches.

OBJECTIVE: The aim of this study was to compare four different techniques for less-invasive coronary artery bypass surgery with and without cardiopulmonary bypass (CPB) in terms of feasibility as well as in terms of the intra- and postoperative course. METHODS: One hundred and fourteen patients were divided into four groups, according to the surgical technique. Group I: minithoracotomy, internal thoracic artery (ITA) harvesting and anastomosis under direct vision using cardiopulmonary bypass (CPB) on the fibrillating heart (n = 31). Group II: sternotomy and beating heart without CPB (n = 13). Group III: MIDCAB with CPB and cardioplegic cardiac arrest using endo-aortic balloon-occlusion, Port Access system (n = 9). Group IV: MIDCAB on the beating heart without CPB (n = 61). In total, 104 single and ten double graft procedures were performed using the radial artery T-graft technique in seven cases (groups III and IV). RESULTS: Harvesting of the ITA graft took 41+/-16.2 min in group I and could be reduced to 31+/-8.3 min in group IV by the use of a specially-designed retractor. Complications were: death (n = 1, group I), myocardial infarction, (n = 1, group I), early occlusion of the graft (n = 1, group IV), early stenosis of the anastomosis (n = 2, groups I and IV), late stenosis of the anastomosis (n = 1, group IV), thrombosis of the femoral vein (n = 1, group III). Postoperative ventilation, ICU and hospital stay were similar among groups. CONCLUSIONS: Based on our results, the following strategy has been developed: MIDCAB without CPB is the preferred technique for one-vessel graft procedures to the left anterior descendens (LAD) or RCA. The Port Access system (with CPB) is reserved as a second option for young patients requiring multiple-vessel grafting to the left coronary circulation (LAD/CX) and as a backup to avoid conversion. Sternotomy and an off-pump technique is used for single-vessel or multiple-vessel graft procedures in selected patients (emergency procedure, acute myocardial infarction, in the very obese).

Algorithms↗
PubMed1998

S-shaped in comparison to L-shaped partial sternotomy for less invasive aortic valve replacement.

OBJECTIVE: Evaluation of less invasive aortic valve replacement to minimize surgical trauma and achieve a better postoperative quality of life. METHODS: Thirty-three patients had aortic valve replacement using a 4-6 cm small incision and partial sternotomy only. Partial sternotomy was performed proximal (16), S-shaped (14) or horizontal (3). Access for cardiopulmonary bypass was via sternotomy (24) or the right femoral vessels (9). Patient age was 58+/-13 years, 21 had aortic stenosis and 12 aortic incompetence. RESULTS: Surgical exposure was sufficient and allowed for uncomplicated AVR in all patients. Mechanical valves (20), conventional bioprostheses (3), stentless bioprostheses (9) or a homograft (1) were implanted. Crossclamp time was not prolonged in comparison to the conventional technique. Intensive care stay and hospital stay were 1 and 10 days, respectively. One patient had to be reoperated for paravalvular leakage, two patients (horizontal sternotomy) had sternal dehiscence. Postoperative pain was low in most patients. CONCLUSION: Less invasive aortic valve replacement is feasible with good functional results. The S-shaped sternotomy approach is advantageous whereas the horizontal sternotomy is no longer performed due to a high rate of instability. This new technique will be further evaluated in comparison to the conventional approach.

Aortic Valve↗
PubMed1998

An experimental approach to quantitative thermal coronary angiography.

Thermal coronary angiography is a noninvasive but not yet quantitative method to intraoperatively assess graft patency in CABG surgery. Aim of this study was to quantify graft flow by measuring perfusion-induced myocardial temperature changes over time. Saphenous vein grafts to the left anterior descending artery were perfused at flow rates of 16-105 ml/min with warm saline. A thermal scanner with a 256 x 256 focal-plane array detector providing a spatial resolution of 1.2 mrad was used. The resulting temperature curves were averaged and a non-linear fit procedure was performed to calculate the time constant (tau) at each flow rate. An increase of myocardial temperature along the LAD with different flow rates could be demonstrated. There was an excellent correlation between the calculated time constant and actual flow (r = 0.96, p < 0.0002). By determining the time constant for different flow rates an estimate of actual graft flow is possible using thermal coronary angiography. Clinical studies have to show if the time constant can be used as a predictor of graft flow in patients.

Animals↗
PubMed1998

Selective photothermolysis of hair follicles by normal-mode ruby laser treatment.

This study was designed to evaluate the effect of selective photothermolysis on dark pigmented hair follicles treated with a normal-mode ruby laser (694-nm wavelength, pulse duration 0.5 ms, fluence 20 J/cm2, spot size 2 mm). In 15 volunteers, four test areas each were selected. After shaving, the first area was irradiated once, the second twice, the third three times and the fourth served as control area. A punch biopsy was taken from each volunteer immediately after the first laser treatment. Four weeks after the last irradiation, no effect was found in six cases and little effect in another six cases (50-90% regrowth). Hair regrowth of less than 30% was observed in only three cases. Eight weeks after the last session, no effect was found in 11 cases, little effect in 2 cases (10%) and less than 30% regrowth in only 2 cases. Twelve weeks after the last treatment, no difference could be detected between the areas untreated and treated by laser. The laser parameters applied in this study do not result in effective epilation of body hair. In some cases, a delay in growth of several weeks was noticed.

Adult↗