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Biomedical subjects

H Schweiger

Publications and source records attributed to H Schweiger.

At least 55 records · Page 3Linked to original sources
PubMed1991

Somatosensory-evoked potentials during carotid artery surgery: experience in 400 operations.

A prospective study was undertaken to determine the efficacy of monitoring somatosensory-evoked potentials (SEP) during carotid artery surgery in predicting a new ischemic neurologic deficit. Three hundred seventy-six patients underwent 400 reconstructions of the internal carotid artery. The mortality rate of the entire series was 0.8%. In 383 procedures, SEP amplitudes were always present during cross-clamping of the internal carotid artery. In spite of that, three neurologic deficits occurred, but all were associated with technical failures and not related to clamping ischemia. Complete loss of SEP amplitudes was noted in 17 procedures. Five of seven patients without an indwelling shunt showed a neurologic deficit after surgery, whereas shunt insertion in 10 resulted in three neurologic deficits. It is concluded that at present SEP recording is an accurate monitoring method in detecting clamping-related cerebral ischemia during carotid artery surgery.

Adult↗
PubMed1991

[Somatosensory evoked potentials in carotid surgery].

During carotid surgery a monitoring device that will identify patients with inadequate cerebral perfusion and impending cerebral damage after carotid clamping is desirable. Such patients may benefit from cerebral protective measures, which should be applied selectively as their use can also lead to complications. METHODS. In order to evaluate the reliability of somatosensory evoked responses as a means of detecting patients with insufficient collateral perfusion after carotid cross clamping, a prospective study involving 482 operations for reconstruction of supraaortic vessels was performed. Somatosensory evoked potentials (SEPs) were recorded from a cervical (C2-Fz) and a parietal (C3'/C4'-Fz) electrode above the ipsilateral hemisphere following stimulation of the contralateral median nerve. RESULTS. In 22 procedures (4.6%) complete flattening of the cortical SEP occurred after carotid cross clamping. In 7 of 9 cases in which no indwelling shunt was used despite electrical silence neurological deficits were found postoperatively. The SEP amplitude was restored in 12 of the remaining 13 patients with complete loss of the SEP after shunt insertion. Only 3 of these patients demonstrated neurological impairment. During 460 operations evoked potentials were always present. Nevertheless, 5 neurological sequelae were noticed despite unchanged SEP after carotid artery clamping. All deficits, however, were caused by embolization and were unrelated to reduced blood flow after carotid cross clamping. CONCLUSIONS. Our results confirm the reliability of SEP monitoring for the detection of significant cerebral ischemia after carotid clamping. In absence of the cortical SEP immediate shunt placement is necessary to avoid neurological deficits. On the other hand, the risks attendant on indiscriminate cerebral support (embolism after shunt placement, cardiac ischemia due to induced hypertension) can be avoided in the presence of cortical potentials. This allows protection of the heart and the brain by anesthetic management and enables the surgeon to perform endarterectomy with no hurry, to avoid technical failure. SEP data may also be helpful in decision making on reoperation to look for sources of embolization. In conclusion, advanced monitoring by somatosensory evoked responses may help to improve the outcome of carotid surgery.

Carotid Arteries↗
PubMed1990

[Acute ischemic myelomalacia and colon necrosis in infrarenal aortic aneurysm].

A 54-year-old man suddenly developed a transverse spinal cord syndrome with paralysis of both legs and diffuse abdominal pain. Spinal compression was excluded by myelography. Subsequent computed tomography, however, revealed an aortic aneurysm of 7 cm diameter. At laparotomy extensive mesenteric ischaemia with necrosis of the entire colon and massive peritonitis were noted. It was not possible, because of the peritonitis, to bypass the aneurysm with a graft and only a colectomy was performed. The patient died 48 hours after admission of prolonged cardiocirculatory failure. Autopsy revealed further multiple organ damage in addition to the ischaemic myelomalacia. The common cause of the findings was probably a sudden drop in blood pressure in the presence of severe generalized arteriosclerosis.

Aorta, Abdominal↗
PubMed1990

[Significance of revascularization in arterially-induced mesenteric infarct].

Until 1957 the only treatment of occlusion of mesenteric arteries was resection of the ischemic part of the bowel. A reduction of the extremely high mortality can be reached by the combination of mesenteric revasularisation with an optional resection of the necrotic parts of the bowel. Based on the experience with 57 patients operated on between 1970 and 1987, the survival rate (greater than 60 days after operation) could be improved by performing this regime. Reasons for this improvement are both the salvage of bowel length and the avoidance of the leak of bowel anastomosis. The latter was observed only in patients treated by bowel resection alone without revascularisation leading to death in three out of four cases.

Aged↗
PubMed1990

[Adaptability of fine-needle biopsy for preoperative and postoperative studies in femoro-crural vascular reconstruction].

During two years we performed 199 pre- and postoperative angiograms on 99 patients with femoro-crural reconstruction. 133 of these were by FNP. In 4.2% of postoperative FNPs (fully anticoagulated patients), there was significant bleeding from the puncture or the operative scar. It was not necessary to reoperate on any bypasses and there were no late complications. As regards the demonstration of the calf vessels. FNP proved itself superior as a pre- and postoperative method. Because of the rapidity of the method, the small amount of contrast required and the minimal trauma, FNP is the method of choice for pre- and post-operative studies of the calf vessels for femoro-crural reconstructions.

Angiography, Digital Subtraction↗
PubMed1990

[Ischemic optic neuropathy (apoplexia papillae) and ischemic micro-infarcts of the retinal nerve fiber layer in extreme internal carotid artery kinking].

The authors report on 2 patients with extreme kinking of the internal carotid artery and ipsilateral, recurrent ischemic optic neuropathy associated with localized microangiopathy of the retinal nerve fiber layer (cotton wool spots). In conjunction with the kinking phenomenon, the atheromatous plaques represent a potential cause of dangerous embolization causing ocular symptoms. The kinking phenomenon may not be diagnosed by Doppler sonography, including duplex B-scan evaluation, and digital subtraction angiography may be necessary. Extreme kinking of the internal carotid artery, which causes ocular embolisms, must be recognized and treated immediately by angioplasty to prevent damage to the eyes and brain.

Aged↗
PubMed1990

Spontaneous disruption of two Greenfield vena caval filters.

Two cases of fractured Kimray-Greenfield vena caval filter struts in patients with pulmonary embolism are reported. Both filters were inserted without complications by means of a jugular approach. Postoperative radiographs demonstrated correct positioning of the filter. During the follow-up period in both cases the devices migrated caudally and penetrated the caval wall; however, the patients remained asymptomatic. Radiographs should be obtained in the follow-up period to ensure proper positioning of the vena caval filter even in asymptomatic patients.

Equipment Failure↗
PubMed1989

Treatment of chronic occlusive arterial disease with pentoxifylline: changes in clinical and haemodynamic parameters.

A prospective study was carried out in 15 patients with peripheral obstructive arterial disease (Fontaine Stage II), with obstructions in the thigh region, to assess the effect of treatment with pentoxifylline on clinical and haemodynamically measurable factors, particularly changes in the post-ischaemic increase in peripheral blood pressure. After a 7-day wash-out period, patients were hospitalized for 1 week and received a daily infusion of 300 mg pentoxifylline plus a 600 mg tablet orally in the evening. They were then treated as out-patients for 2 weeks, receiving 1200 mg pentoxifylline orally per day. Pain-free and maximum possible walking ranges, using a treadmill ergometer, were determined on Days 7, 14, 21 and 28 of the study. Measurements were made at the same intervals, using Doppler ultrasound, and the peripheral resting blood pressure index and post-ischaemic blood pressure index calculated. The results showed significant improvement in both pain-free and maximum walking range after intravenous and oral therapy and this was particularly noticeable in those patients who, before treatment, had a walking range of less than 150 metres: their pain-free range doubled in the first week. There was a slight increase in the resting Doppler blood pressure indices during treatment and a clear, significant increase in the post-ischaemic pressure index 90 and 120 sec after the induced ischaemia ended.

Adult↗
PubMed1988

Ischemia-induced alterations of mitochondrial structure and function in brain, liver, and heart muscle of young and senescent rats.

Young and senescent rats (3 and 28-30 months old) were subjected to complete ischemia at 37 degrees C in order to study function and structure of mitochondria isolated from liver, heart muscle, and brain. The rates of energy-coupled respiration and ATP synthesis were found to decrease progressively in relation to time of ischemia. The respiratory rates in the absence of ADP (state 4 respiration) did not increase after exposure to ischemia, suggesting that ischemia primarily affects electron transport rather than the energy coupling system. Mitochondria of heart muscle were more affected by ischemia than mitochondria of brain and liver. Liver and heart muscle mitochondria obtained from young rats were found to be slightly more sensitive to short periods of ischemia than those isolated from senescent animals.

Adenosine Triphosphate↗
PubMed1987

[Combined drug-surgical therapy of acute ischemia syndrome].

Acute ischaemia of the lower leg caused by arterial thrombosis often leads to amputation. Thrombolytic therapy of a distal arterial thrombosis yields unsatisfactory results when lower leg thrombosis is superimposed on chronic superficial femoral artery occlusion. 31 cases of acute ischaemia of the lower leg were initially treated with short bursts of catheter lysis followed by surgical reconstruction. Improved results were obtained through the use of combined medical and surgical treatment.

Acute Disease↗
PubMed1987

[Angiographic imaging of blood vessels of the lower leg in acute ischemia: comparison of intravenous DSA and intra-arterial DSA].

In patients with acute lower leg ischemia i.v. DSA was compared with i.a. DSA or fine needle injection. The distal flow off was only demonstrated in i.a. DSA, the plantar arch only with fine needle injection. I.v. DSA is limited to the demonstration of the popliteal artery. Consequently fine needle injection should be used in diagnosis of acute peripheral ischemia.

Angiography↗
PubMed1987

Avoiding early failure of tibial prosthetic bypass grafts.

In a series of 97 tibial reconstructions using PTFE bypass grafts the value of perioperative anticoagulation was studied. Acetylsalicylic acid as well as low-dose heparin treatment resulted in a high graft failure rate during the first postoperative days (42%). Patency could be restored in half of the cases by simple thrombectomy. When heparin was given at a dose of 1000 I.U. per hour for two days the graft failure rate was 14%. Only one out of eight thrombosed grafts could be re-opened by thrombectomy. Long-term patency, however, was similar in both groups. We conclude that perioperative heparin treatment is a suitable method to avoid unnecessary thrombectomies of long prosthetic bypass grafts.

Blood Vessel Prosthesis↗
PubMed1985

[Early and late results following 244 reconstructions of the internal carotid artery with contralateral internal carotid occlusion].

Between December 1974 and March 1985 244 reconstructions of the internal carotid artery with contralateral occlusion were performed. 7.3% of the patients were asymptomatic, 48.4% had typical transient ischemic attacks and 44.3% had a completed stroke. The postoperative mortality was 2.0% and a permanent neurologic deficit occurred in 3.3%. An intraluminal shunt was used in only 5.4%. The long-term survival rate after 5 years was 65.2 +/- 4.8%. In the follow-up period of 103 months 9.2% of the patients had a new stroke.

Arteriosclerosis↗
PubMed1984

[Potency disorders before and after pelvic artery reconstruction: objectification by measuring penile artery pressure].

Penile artery pressure was measured in 38 patients before and after aorto-iliac reconstruction using the Doppler technique. In 14 patients a markedly reduced penile pressure was found preoperatively which was significantly enhanced in 71% after operation. In 16% of all cases postoperative penile pressure was lower than the preoperative value. An improvement of sexual impairment was observed in 37% of the patients, while 26% reported a decrease of sexual function after operation. The reason seems to be an operative damage to the preaortal nerve plexus in most cases. Therefore, in younger patients with unilateral iliac artery occlusive disease an extraanatomical reconstruction is recommended.

Adult↗