PubMed Health⌕ Search

Biomedical subjects

R Kuntz

Publications and source records attributed to R Kuntz.

At least 19 recordsLinked to original sources
PubMed2001

Comparison of PRE-dilatation vs direct stenting in coronary treatment using the Medtronic AVE S670 Coronary Stent System (the PREDICT trial).

Current stent delivery systems make primary stenting (stent placement without predilatation) possible, but few controlled trials have been performed to evaluate the success, safety, cost saving, and potential benefit of this approach in reducing late restenosis. The Comparison of PRE-Dilatation Versus Direct Stenting In Coronary Treatment using the Medtronic AVE S670 Coronary Stent System trial was a 399-patient study comparing results with the Medtronic-AVE S670 stent to objective performance criteria based on prior approved stents, with subrandomization to direct stenting versus stenting after balloon predilatation. Overall, results with the S670 stent showed excellent success and safety, with delivery success of 99%, a 14-day adverse event rate of 6.8% (including 6.5% non-Q-wave myocardial infarction), and favorable angiographic (20%) and clinical (12%) restenosis rates. Direct stenting was successful in 92% of cases, with a 99.5% secondary success rate including additional pretreatment of initially unsuccessful direct-stenting attempts, and no increase in complications. There were modest ( approximately 10%) savings in fluoroscopy time, contrast use, and a decrease in angioplasty balloon use (0.6 vs 1.3 balloons/case), but no reduction in clinical or angiographic restenosis. Patients treated later in the study, with a device that had less balloon extension beyond the edges of the stent, had slightly lower angiographic restenosis rates (19% vs 23%). In conclusion, the S670 stent showed excellent overall performance. Although direct stenting was safe and highly successful, it offered only modest cost savings, and no reduction in late restenosis compared with stenting after predilatation.

Catheterization↗
PubMed2001

SMART: The microstent's ability to limit restenosis trial.

In this randomized, prospective, multicenter trial (n = 661) of patients with de novo or restenotic coronary lesions, 330 patients received the MicroStent(R) II (MSII), and 331 received the Palmaz-Schatz (PS) stent. The short-term procedural success rates were 94.4% and 95.7%, respectively (P = 0.47). The 30-day cumulative incidence of major adverse events [death, myocardial infarction, CVA, target lesion revascularization (TLR)] was 6.4% for the MSII and 4.5% for the PS stent (P = 0.31). The in-stent binary restenosis rate at 6 months was 25.2% for the MSII and 22.1% for the PS stent (P = 0.636). Using Kaplan-Meier estimates, the incidence of clinically driven TLR was 8.9% for the MSII and 9.2% for the PS stent at 180 days; at 270 days, it was 12.8% and 12.1%, respectively (P = 0.83). MSII and the PS stents were comparable with respect to short-term procedural success, complications, and late clinical and angiographic restenosis.

Aged↗
PubMed2000

The PARAGON stent study: a randomized trial of a new martensitic nitinol stent versus the Palmaz-Schatz stent for treatment of complex native coronary arterial lesions.

A new martensitic nitinol stent with improved flexibility and radiopacity was tested to evaluate whether these differences improve initial or long-term outcome. Patients who underwent percutaneous revascularization of a discrete native coronary lesion were randomly assigned to the new stent (PARAGON, n = 349) or to the first-generation Palmaz-Schatz (PS) stent (n = 339). The primary end point was target vessel failure at 6 months (a composite of cardiac or noncardiac death, any infarction in the distribution of the treated vessel, or clinically indicated target vessel revascularization). Secondary end points were, among others, device and procedural success and angiographic restenosis. Mean age was 62 years; diabetes was present in 21% of patients, prior bypass surgery in 6%, and recent infarction in 22% (p = NS for comparison between the 2 randomized arms). The PARAGON stent group had smaller reference vessels (2.97 vs 3.05 mm, p = 0.05), more prior restenosis (8.0% vs 4.5%, p = 0.07), and a longer average stent length (21.3 vs 19.4 mm, p < 0.05). Device success was significantly higher in the PARAGON arm (99.1% vs 94.3%, p < 0.05). Death and infarction at 6-month follow-up were infrequent in both groups. There was no significant difference in death (2.0% vs 1.2%, p = 0.546), but a higher rate of infarction for the PARAGON cohort (9.2% vs 4.7%, p = 0.025). Although target vessel failure (20.3% vs 12.4%, p = 0.005) and target lesion revascularization (12.0% vs 5.9%, p = 0.005) were higher in the PARAGON group, there was no significant difference in 6-month follow-up in in-stent minimal lumen diameter or in the rate of binary angiographic restenosis. Both PARAGON and PS stents are safe and associated with infrequent adverse events. The PARAGON stent can be delivered more frequently than the first-generation PS stent. Although there was no significant difference in in-stent minimal lumen diameter or the frequency of angiographic restenosis, clinical restenosis was more frequent in the PARAGON group.

Adult↗
PubMed2000

Usefulness of stent length in predicting in-stent restenosis (the MULTI-LINK stent trials).

The cumulative experience of 4 clinical trials using the MULTI-LINK coronary stent design was analyzed. Multivariable logistic regression identified postprocedure in-stent minimum lumen diameter (p = 0.0001), stent length (p = 0.0038), smoking (p = 0.0105). and diabetes (p = 0.0803) as the most important predictors of in-stent restenosis at late (6- to 9-month) angiographic follow-up.

Adult↗
PubMed2000

Treatment of lesions with thrombus: beyond stents and GP IIb/IIIa inhibitors.

In the presence of an intracoronary thrombus, percutaneous coronary intervention (PCI) will frequently lead to complications. Glycoprotein IIb/IIIa blockade as adjunct to PCI is very effective in patients with non-occlusive clots and biochemical evidence of platelet micro-embolization. Thrombotically-occluded vessels still remain a major clinical problem. This provides a rationale for thrombus debulking prior to PCI. A powerful antiplatelet agent used in combination with a thrombus debulking strategy and stenting of the underlying ruptured plaque offers the potential for further enhancement of PCI. Protection against embolization could potentially be optimized with the use of anti-embolization devices and covered stents.

Angioplasty, Balloon, Coronary↗
PubMed1999

Echo planar perfusion imaging with high spatial and temporal resolution: methodology and clinical aspects.

The purpose of the present study was to analyse specific advantages of calculated parameter images and their limitations using an optimized echo-planar imaging (EPI) technique with high spatial and temporal resolution. Dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) was performed in 12 patients with cerebrovascular disease and in 13 patients with brain tumours. For MR imaging of cerebral perfusion an EPI sequence was developed which provides a temporal resolution of 0.68 s for three slices with a 128 x 128 image matrix. To evaluate DSC-MRI, the following parameter images were calculated pixelwise: (1) Maximum signal reduction (MSR); (2) maximum signal difference (delta SR); (3) time-to-peak (Tp); and (4) integral of signal-intensity-time curve until Tp (SInt). The MSR maps were superior in the detection of acute infarctions and delta SR maps in the delineation of vasogenic brain oedema. The time-to-peak (Tp) maps seemed to be highly sensitive in the detection of poststenotic malperfused brain areas (sensitivity 90%). Hyperperfused areas of brain tumours were detectable down to a diameter of 1 cm with high sensitivity (> 90%). Distinct clinical and neuroradiological conditions revealed different suitabilities for the parameter images. The time-to-peak (Tp) maps may be an important advantage in the detection of post-stenotic "areas at risk", due to an improved temporal resolution using an EPI technique. With regard to spatial resolution, a matrix size of 128 x 128 is sufficient for all clinical conditions. According to our results, a further increase in matrix size would not improve the spatial resolution in DSC-MRI, since the degree of the vascularization of lesions and the susceptibility effect itself seem to be the limiting factors.

Adult↗
PubMed1999

A cerebellar-like terminal and postural tremor induced in normal man by transcranial magnetic stimulation.

Trains of repetitive transcranial magnetic stimulation (TMS) at 10-30 Hz and intensities of 90-120% motor threshold were delivered through a figure of eight coil over the motor cortex while normal subjects made either rapid, self-terminated (ballistic) wrist movements or maintained the position of their wrist at a fixed angle. Movement kinematics and EMG activity in antagonistic forearm muscles were analysed. In the ballistic task, repetitive TMS had little effect on the velocity or acceleration of the initial segment of the movement, although it induced large terminal oscillations (tremor) around the target position at frequencies between 4.4 and 7.2 Hz. The likelihood that tremor would occur increased with increasing stimulus intensities or frequencies. It was maximal with stimulation over the forearm area, and decreased with stimulation over the leg area, or over parietal sites; there was no tremor during stimulation of cervical nerve roots. The frequency of the induced tremor was independent of the rate of stimulation and did not depend on the presence of excitatory and inhibitory motor responses to the stimulus. Stimulation could also induce tremor of the same frequency in the fixed task, but only during co-contraction of forearm muscles. The amplitude of tremor was proportional to the level of co-contraction. Clinically, the tremor induced by repetitive TMS appeared very similar to cerebellar tremors. In order to confirm this we investigated two cerebellar patients, one with autosomal dominant cerebellar ataxia and the other with multiple sclerosis. Both of them had a terminal tremor of 6-7 Hz in the wrist movement task. In the holding task, the amplitude of their postural tremor increased with the level of co-contraction in forearm muscles. Since the frequency of repetitive TMS-induced tremor was independent of stimulus parameters, we conclude that it represents some intrinsic property of the CNS. We suggest that the tremor is caused by disruption of cortical processes involved in terminating a voluntary movement or maintaining a posture. Similarities to cerebellar patients suggest that repetitive TMS may cause tremor by interfering with adaptive cerebellar afferent inflow to motor cortex. Repetitive TMS-induced tremor, therefore, may represent a model of some forms of cerebellar tremor in man.

Adult↗
PubMed1998

Image quality of spiral CT versus conventional CT in routine brain imaging.

OBJECTIVE: Aim of the study was to compare image quality of spiral (helical) versus conventional (sequential) routine brain scans obtained on a spiral CT scanner of the latest generation. MATERIALS AND METHODS: In a prospective study 60 patients scheduled for cranial CT were examined in spiral (27 cases) or conventional technique (33 cases) after randomization. Two blinded observers rated artifacts, gray--white-matter contrast and overall image quality. RESULTS: No significant differences in artifacts were detected. Concerning gray--white-matter contrast and overall image quality, none or small differences in favour of conventional scans were found depending on the observer. CONCLUSION: On a modern scanner image quality of spiral brain scans in adults is nowadays comparable to or only slightly less than that of conventional scans. On such a machine, spiral mode can be recommended if, for example, rapid scanning or high-quality secondary reconstructions are needed.

Artifacts↗
PubMed1998

Acute disseminated encephalomyelitis following Pontiac fever.

We report the case of a 35-year-old woman who developed headache and psychosis and gradually became comatose within 3 weeks after a flu-like infection. MRI revealed bifrontal demyelination consistent with acute disseminating encephalomyelitis (ADEM). Two different cerebrospinal fluid samples were positively tested for Legionella cincinnatiensis by direct sequencing of a PCR-amplified Legionella-specific fragment. This result made it possible to interpret the initial symptoms as Pontiac fever. We think it most likely that this is a case of ADEM following the very rare situation of a systemic infection with L. cincinnatiensis. A review of the literature on Legionella-associated encephalopathy suggests that some of these cases may also have had ADEM.

Adult↗
PubMed1994

Retroperitoneal hematoma after cardiac catheterization: prevalence, risk factors, and optimal management.

PURPOSE: Retroperitoneal hematoma is an unusual, but potentially serious, complication after cardiac catheterization. The predisposing factors, typical presentation, and clinical course of this iatrogenic complication are identified, and the role of surgery in its treatment is defined. METHODS: A retrospective review of 9585 femoral artery catheterizations over a 5-year period allowed identification and evaluation of all patients with retroperitoneal hemorrhage. RESULTS: Retroperitoneal hematoma developed in 45 patients (overall prevalence 0.5%), with the highest frequency after coronary artery stenting (3%). In the group of patients who underwent coronary artery stenting, statistically significant predictors of this complication included protocol for sheath removal, female sex, nadir platelet count, and excessive anticoagulation. Signs and symptoms included suprainguinal tenderness and fullness in 100%, severe back and lower quadrant pain in 64%, and femoral neuropathy in 36%. Most patients were treated successfully with transfusion alone. Seven patients (16%) required operation; in four, hypotension unresponsive to volume resuscitation developed early after catheterization; and, in three, a progressive fall in hematocrit level led to surgery 24 to 72 hours after catheterization. CONCLUSIONS: Retroperitoneal hematoma after cardiac catheterization can usually be treated by transfusion alone. A small subset of patients who have development of hypotension unresponsive to volume resuscitation require urgent operation.

Aged↗
PubMed1990

[Experience after one year's computer-assisted determination and evaluation at the alcohol dehydrogenase laboratory].

The processing of blood alcohol measurements by alcohol dehydrogenase method (ADH) was improved by using a tailored software program. The program is written in Turbo BASIC and requires an IBM Personal Computer (PC/XT/AT) or compatible with at least 640K memory and a graphic adapter (EGA or Hercules). All features of the program are available from the menu bar with pull down menus. The program stores on disk or harddisk the optical density values measured with an HITACHI spectrophotometer. After the measurement the calculation of alcohol concentration is accomplished by the program. The results can be transferred and further handled with database systems (e.g. DBASE III). Stored values are used to calculate the reproducibility of calibration and the precision of single determinations.

Alcohol Dehydrogenase↗
PubMed1989

[Programming and structure of a relation-oriented data bank system for registration, blood alcohol values and documentation of findings at the forensic medicine institute of the Heidelberg University].

We report on a data base system for general registration including blood alcohol results which is in operation at the Institute of Forensic Medicine at Heidelberg University since january 1987. It is run on personal computers using dBase III plus as data base software. Working with the system has been adapted to the mode of operation hitherto. It's main purpose is to offer a general mean to standardize the documentation of results in the different fields of forensic medicine. At present it is run parallel with the registration by means of hand-written books. It's main advantage is the rapid search for all occurring names and files. Blood alcohol results are typed at the screen and printed out on the institute's standard form, with the expert's opinion being composed of text blocks. The essential data are extracted and transferred to the data base. A network of personal computers at different locations in the institute will be installed in the near future. A print-out of the data base will replace the hand-written registration, and the registration files will be completed by result files.

Accidents, Traffic↗
PubMed1980

[The angiographic diagnosis of islet cell tumours. Results in 34 patients (author's transl)].

Between 1965 and 1979, 34 patients with organic hyperinsulinism were examined angiographically. By observing the following points it should be possible to diagnose tumours greater than 1 cm, whatever their position in the pancreas: 1) Use of high performance generators and tubes which permit one to employ fine focus, low kv and high mAs. 2) Optimum imaging systems (carbon fibre table top, high intensity screens). 3) Selective catheterisation, large quantities of contrast per unit time and adequate duration of the filming sequence. 4) Pharmacoangiography and subtractions may be valuable in some cases.

Adenoma, Islet Cell↗
PubMed1976

[The diagnosis and therapy of mediastinal tumors (author's transl)].

From 1965 to 1973, 82 patients were operated on for mediastinal tumor. 42.7% of them were incidental radiological findings. Preoperatively, 66% of the mediastinal tumors were not morphologically confirmed. The lethality of the operation was 1.22%. Thymomas (29.3%) were the most frequent findings. 34.2% were malignant. While most patients with benign mediastinal tumors are cured by the operation, the 5 year survival rate for those with malignant tumors was 22%. Further special investigative procedures should only follow a guiding survey radiography in two planes if they can be expected to provide essential information on operability, operational tactics and approach.

Adolescent↗