Biomedical subjects

G Fraedrich

Publications and source records attributed to G Fraedrich.

At least 37 records · Page 2Linked to original sources

PubMed2001

Serial CT volume measurements after endovascular aortic aneurysm repair.

PURPOSE: To evaluate the efficacy of transluminal stent-graft placement in aortic aneurysms using postoperative enhanced spiral computed tomographic (CT) volumetric measurements of the aneurysm sac, the intra-aneurysmal vascular channel (IAVC), the thrombus, and the stent-graft. METHODS: Among 53 patients (45 men; mean age 74 years, range 59-85) who underwent elective endovascular aortic aneurysm repair, 37 patients with 27 abdominal and 10 thoracic aortic aneurysms completed at least a 6-month follow-up that included computerized CT volumetric analysis prior to discharge and at 3, 6, 12, 24, and 36 months. A variety of bifurcated (n = 23) and tube (n = 14) stent-grafts were observed for signs of endoleak and aneurysm enlargement. RESULTS: Mean follow-up was 16 months (range 6-48). Total aneurysm volumes and thrombus volumes decreased, whereas IAVC and stent-graft volumes increased over time. Between the postoperative and 12-month imaging studies, reductions in total aneurysm (p 0.011) and thrombus (p < 0.001) volumes were significant. No statistically significant difference in volume changes for the aneurysm sac (p = 0.555) or the thrombus (p = 0.920) was found when comparing the 24 patients without primary leak to the 12 with primary type-II leak. In all 5 cases with secondary leak, the volume of the aneurysm sac increased after initial shrinkage. CONCLUSIONS: Postoperative CT volumetric analysis is an effective tool for evaluating the outcome of endovascular aortic aneurysm repair. Thrombus volume measurements are more accurate than total aneurysm volumes. In patients in whom contrast agents are contraindicated, volume measurements can also be obtained without the use of contrast.

Age Factors↗

PubMed2001

Fleroxacin uptake in ischaemic limb tissue.

Antibiotic application to patients with ischaemia of lower limbs may be indicated to avoid or treat infection of soft tissues. Fleroxacin, a fluoroquinolone, active against various Gram-negative and Gram-positive organisms may be used for this purpose. We evaluated the diffusion of fleroxacin into bone, subcutaneous fat, muscle and tendon tissues of lower limb tissue after a 400 mg i.v. dose. Concentrations in ischaemic tissues were similar to those found in non-ischaemic sites. Since the maximum antibiotic levels found were lower than the MICs of various pathogens relevant for infection, we suggest to increase the dose used for this peri-operative prophylaxis to 800 mg.

Adipose Tissue↗

PubMed2001

Clinical and objective data on spinal cord stimulation for the treatment of severe Raynaud's phenomenon.

Ischemic vascular disease of the upper extremity represents a difficult therapeutic problem wherein medical treatment often fails. Epidural spinal cord stimulation has been shown to be an effective alternative in severe peripheral arterial disease. Although this method has been used for nearly two decades only limited experience exists in Raynaud's phenomenon of the upper limbs. In addition objective parameters to prove therapeutic success are not well defined. Herein we describe a patient with severe primary Raynaud's phenomenon over several years who had significant pain relief and complete healing of ischemic digital ulcerations after spinal cord stimulation. Pain level was evaluated using a visual rating scale before and after surgery. Microcirculatory parameters were assessed before and after spinal cord stimulation by capillary microscopy and laser Doppler anemometry. Significant improvement of red blood cell velocity, capillary density, and capillary permeability was demonstrated. At follow-up 18 months after surgery the patient had no complaints and all ulcerations of her fingertips had healed. Spinal cord stimulation appears to be an effective treatment in severe cases of Raynaud's phenomenon and we recommend its use in the case of failed medical therapy. Pain rating and capillary microscopy enable one to assess and visualize the effects of spinal cord stimulation.

Aged↗

PubMed2000

Treatment of Stanford type B aortic dissection with stent-grafts: preliminary results.

PURPOSE: To evaluate the feasibility and safety of endovascular stent-graft placement in treating Stanford type B aortic dissection. MATERIALS AND METHODS: Seven patients underwent endovascular stent-graft placement for type B aortic dissection. Five patients had acute and two had chronic dissection. In five patients, the proximal entry tear was within 2 cm of the origin of the left subclavian artery, and in two patients it was beyond this site. In three patients, the noncovered proximal portion of the stent-graft was placed across the origin of the left subclavian artery. The efficacy of the procedure was assessed at follow-up studies 3, 6, 12, and 24 months after intervention. RESULTS: The procedure was technically and clinically successful in six patients (86%). The left subclavian artery remained patent in all patients. In two patients with involvement of aortic branches, endovascular stent-graft placement restored adequate blood flow to the compromised branches. One patient was readmitted 1 month later because the dissection extended into the ascending aorta. In all but this patient, closure of the entry tear and thrombosis of the false lumen along the stent-graft were achieved. All false lumina shrank considerably. The mean follow-up time was 14 months (range, 1-25 months). CONCLUSION: Type B aortic dissections within and beyond 2 cm of the origin of the left subclavian artery can be treated safely and effectively by means of endovascular stent-graft placement.

Adult↗

PubMed1998

Co-expression of p53 and MDM2 in human atherosclerosis: implications for the regulation of cellularity of atherosclerotic lesions.

Atherosclerosis is a fibroproliferative disease of the arterial intima. It was recently found that wild-type p53 (wt p53) accumulates in human atherosclerotic tissue. Wt p53 is a cell cycle regulator involved in DNA repair, DNA synthesis, cell differentiation, and apoptosis and might therefore make an important contribution to the cellularity of atherosclerotic plaques. The product of the MDM2 gene is a nuclear protein which forms a complex with p53, thereby inhibiting the negative regulatory effects of wt p53 on cell cycle progression. In order to address a potential role of the interaction of p53 with MDM2 for the regulation of cellularity in atherosclerotic tissue, 22 carotid atheromatous plaques from patients undergoing endarterectomy were studied to determine the presence of p53 immunoreactivity (IR), MDM2 IR, cell proliferation as evidenced by MIB1/Ki-67 IR and DNA fragmentation by in situ terminal transferase-mediated dUTP 3' end labelling (TUNEL), as a marker for apoptosis. p53 IR localized to areas with evidence of chronic inflammation (22/22) and was observed in virtually all cell types in 68.79 +/- 7.51 per cent of the nuclei. p53 staining in the control tissue from human internal mammary arteries was present in 0.2 +/- 0.29 per cent of the cells (P < or = 0.002). MDM2 IR was present in all cases (22/22) in macrophages and smooth muscle cells (SMCs) in 60.53 +/- 8.32 per cent of the nuclei (controls: 0.8 +/- 0.65 per cent, P < or = 0.002) and co-localized with p53 IR as shown by examination of adjacent sections and by double immunofluorescence labelling. Importantly, co-immunoprecipitation and western blot analysis revealed that p53 and MDM2 were physically associated, indicating that MDM2-p53 complex formation takes place in vivo in human atherosclerotic tissue. Positive TUNEL staining and MIB1/Ki-67 IR present in 3.01 +/- 1.27 per cent of the nuclei (controls: 0 per cent, P < or = 0.002) localized to the same plaque compartments as p53 IR and MDM2 IR. Thus, the fate of cells with p53 accumulation may depend on the interaction and the stoichiometry of the p53 and MDM2 proteins. Cells were indeed found with strong p53 accumulation and nuclear morphology typical for apoptosis and there were a few MIB1/Ki-67-positive cells with co-expression of MDM2, indicating a possible role for MDM2 in reversing the negative regulatory effects of p53 for cell cycle progression. The nuclear co-localization of p53 IR with MDM2 IR and the co-immunoprecipitation assay indicate the presence of p53-MDM2 complex formation in vivo in human atherosclerotic tissue. The destiny of individual p53 and MDM2-co-expressing cells either to undergo p53-dependent apoptosis or to re-enter the cycle of cell proliferation may depend on the relative ratios of the two proteins. p53 and MDM2 may therefore play an important role in regulating cellularity and inflammatory activity in human atherosclerotic plaques.

Apoptosis↗

PubMed1998

Increased tissue endothelin-1-like immunoreactivity in the internal mammary artery of patients with diabetes or hypercholesterolemia modulates the graft flow in the peri-operative period.

OBJECTIVE: Peri-operative ischemic episodes following coronary artery bypass grafting with the internal mammary artery (IMA) are thought to be due to a vasospasm of this conduit. Endothelin-1 (ET-1) is a potent vasoconstrictor by itself and increases the response to other vasoconstrictor stimuli. This study focused on the possible role of an enhanced tissue ET-1-like immunoreactivity in the perioperative reaction of the IMA in patients with diabetes or hypercholesterolemia. METHODS: Specimens of the distal part of the IMA from 46 patients (mean age 58.5 years, four women, 42 men) were studied prospectively. Nine of those patients were diabetic and 26 had evidence of hypercholesterolemia. Another cohort of 20 IMA specimens was stained retrospectively; 10 of those biopsies were from patients that had experienced transient ischemic events peri-operatively in the myocardial area supplied by the IMA. The biopsies were examined histologically and immunohistochemically (rabbit polyclonal ET-1 antiserum, three-step avidin-biotin complex) with regard to their immunoreactivity to tissue ET-1. RESULTS: An immunoreactivity to ET-1 (graded 0-3) was present in 89% of the biopsies. The reactivity was significantly higher in patients with hypercholesterolemia ( 1.92+/-0.74) when compared to controls (1.0+/-0.63) (P = 0.04). The reactivity was also increased in patients with non-insulin-dependent diabetes mellitus (2.1+/-0.79), when compared to controls (P = 0.02). Mostly transient ischemic events in the area supplied by the IMA seemed to occur more frequently when the biopsies revealed a higher immunoreactivity to ET-1. They showed an increased reactivity to ET-1 (2.27+/-0.76) compared to 10 patients with an uneventful peri-operative course (1.66+/-0.71 ) (P = 0.04). CONCLUSIONS: This study provides evidence that the internal mammary artery is not a passive conduit. Vasospasm or vasoconstriction, in particular at its distal end, may occur more frequently in patients with hypercholesterolemia or diabetes, and may lead to post-operative ischemic events.

Biopsy↗

PubMed1996

[Results of surgical treatment of acute traumatic aortic rupture].

Between 1967 and 1994 48 patients have been treated at our institution for acute rupture. Two patients died before operation, in two cases the operative attempt had to be abandoned with irreversible cardiopulmonary arrest, and in 44 patients surgical correction could be performed, The rupture was complete in 14 cases and incomplete in 30. In 25 patients surgery consisted of direct suture, in one patient an aortoplasty was performed, and in 18 patients a dacron tube interposition was necessary. In 7 cases the clamp and repair technique was applied, and in 37 cases extracorporeal circulation was installed. The hospital mortality amounted to 18% and was mainly contributable to the concomitant injuries. Two patients presented with paraplegia at admission, both died; postoperative paraplegia occurred in two instances, once after 48 hours. The late results were in the majority of the cases influenced by orthopedic or neurological sequelae, only one patient had to be reoperated for a false aneurysm. Our results and the review of the literature lead to the following conclusions: In spite of an optimized emergency care system, many patients with aortic rupture die before any surgical intervention. The installation of extracorporeal circulation can decrease the incidence of postoperative paraplegia; in our experience the administration of heparin does not increase the risk of bleeding from concomitant injuries. Direct suture represents the correction of choice. The long-term results are excellent.

Adolescent↗

PubMed1996

[Surgical therapy of chronic traumatic aortic aneurysm].

Rupture of the aorta that usually occurs with major blunt trauma of the chest is associated with a high mortality, and only 2% of the patients survive long enough to develop a false aneurysm. Although symptom-free latent period is not rare, there is evidence of progression. Since 1970 we operated on 28 patients (24 male and 4 female, mean age 41.2 years) for chronic traumatic aneurysm of the descending aorta. A previous blunt trauma of the chest had certainly occurred in 23 cases (3 months to 20 years before) and was likely in 4 patients; in one young woman the aneurysm developed after percutaneous angioplasty of a coarctation. In 26 patients surgical repair consisted in a Dacron tube interposition, and in 2 cases patch repair was adequate. In 11 cases the "clamp and repair" technique was applied, while in 17 patients extracorporeal circulation was established to perform the reconstruction, two of these cases were operated with hypothermic circulatory arrest. Although there was no correlation between the occurrence of complications and the applied procedure, we lately turned to establish cardiopulmonary bypass in all cases with regard to a better control of the hemodynamics during clamping, the possibility of direct retransfusion of blood, and the option to extend the procedure, if necessary. In view of the facts, that traumatic thoracic aneurysms develop late complications in about 75% of the cases, and the morbidity in elective surgery is of a low figure, we conclude, that surgery of such lesions is mandatory, once the diagnosis has been established, and that an expectant attitude in the treatment is justified only in exceptional cases.

Adult↗

PubMed1995

Positive and negative inotropic effects of DL-sotalol and D-sotalol in failing and nonfailing human myocardium under physiological experimental conditions.

BACKGROUND: DL-Sotalol has class III antiarrhythmic activity through prolongation of the repolarization phase of the action potential as well as beta-adrenoceptor-blocking properties. Although the former effect was found to exert positive inotropic effects in animal experimental studies, the latter may be detrimental in heart failure due to negative inotropism. In contrast to DL-sotalol, D-sotalol is suggested to exert only positive inotropic effects, which were never tested in isolated human myocardium. METHODS AND RESULTS: Therefore, we investigated the effects of racemic DL-sotalol and its enantiomer D-sotalol in human right atrial muscle strip preparations and in left ventricular muscle strip preparations from nonfailing and end-stage failing human hearts. DL-sotalol and D-sotalol significantly (P < .01) increased peak developed force in atrial preparations by 14.0 +/- 3.4% and 16.7 +/- 3.8%, respectively, but had no effect in ventricular myocardium. In nonfailing ventricular myocardium, both DL-sotalol and D-sotalol shifted the dose-response curve for isoproterenol to higher concentrations (P < .01); however, DL-sotalol was 100-fold more effective than D-sotalol. In non-failing myocardium, a positive force-frequency relation was found between 30 and 120 beats per minute, but isoproterenol was much more powerful in its inotropic effects. In failing myocardium, reduction in stimulation rate from 120 to 30 beats per minute increased peak developed force more pronounced than did the application of isoproterenol. CONCLUSIONS: (1) D-Sotalol has no relevant beta-adrenoceptor-blocking activity compared with DL-sotalol. (2) Neither DL-sotalol nor D-sotalol exhibit positive inotropic effects in human left ventricular myocardium. (3) Heart rate reduction increases contractile force in end-stage failing human myocardium due to an inverse force-frequency relation and thereby counteracts the potential negative inotropic properties of beta-blockade.

Adrenergic beta-Agonists↗

PubMed1995

[The aortic arch as source of thromboembolism events--significance of echocardiography diagnosis].

A 43-year-old woman presented with acute embolic occlusion of the left brachial artery. She was immediately treated by surgical embolectomy. After exclusion of other possible embolic sources, the transthoracic and transesophageal echocardiographic examination revealed a floating thrombus in the aortic arch. There-upon an aortotomy and thrombectomy was performed and showed a normal wall structure of the thoracic aorta except for a minimal ulcerated lesion of the intima at the aortic arch. This case confirms that transthoracic and transesophageal echocardiography are the diagnostic methods of choice for detecting thromboembolic sources originating in the heart or thoracic aorta.

Adult↗

PubMed1994

Beta 2-adrenergic receptor and angiotensin II receptor modulation of sympathetic neurotransmission in human atria.

The aim of the present study was to investigate beta-adrenergic receptor and angiotensin II (Ang II) receptor modulation of norepinephrine release in human atria. Slices of human atrial appendages were incubated with [3H]norepinephrine, superfused with Krebs-Henseleit solution, and electrically stimulated in superfusion chambers. Pretreatment of the tissue with 6-hydroxydopamine (1.2 mmol/L) before the [3H]norepinephrine incubation to destroy sympathetic nerves reduced the uptake of radioactivity and abolished the stimulation-induced (S-I) outflow of radioactivity. Furthermore, S-I outflow of radioactivity was prevented by the addition of tetrodotoxin (1 mumol/L) to and omission of extracellular Ca2+ from the superfusion solution. Separation of [3H]norepinephrine from its metabolites revealed that the S-I outflow of radioactivity was mainly composed of intact [3H]norepinephrine. Thus, the S-I outflow of radioactivity was taken as an index of norepinephrine release. Isoproterenol (0.001 to 0.1 mumol/L) dose-dependently enhanced the S-I outflow of radioactivity. The concentration-response curve of isoproterenol was shifted to the right by the selective beta 2-adrenergic receptor antagonist ICI 118551 (0.01 and 0.1 mumol/L) but not by the beta 1-adrenergic receptor-selective antagonist atenolol (0.3 and 30 mumol/L). Ang II (0.001 to 1.0 mumol/L) also dose-dependently enhanced S-I outflow of radioactivity. The facilitatory effect of Ang II was blocked by either the peptide Ang II receptor antagonist saralasin (1.0 mumol/L) or EXP 3174 (0.1 mumol/L), the in vitro active form of the nonpeptide Ang II receptor antagonist losartan. The cell-permeable cAMP analogue 8-bromo-cAMP (30 to 300 mumol/L) dose-dependently enhanced S-I outflow of radioactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1993

[Limitation of Doppler echocardiography in evaluation of aortic valve prostheses]].

Doppler echocardiography has been widely used as a noninvasive method to evaluate valvular heart diseases. However, the diagnostic impact of Doppler echocardiography in the evaluation of prosthetic valves is discussed controversially. Reasons are, on one hand, the high variabilities of transvalvular gradients observed for normal prosthetic devices and, on the other hand, results of experimental in vitro studies demonstrating an impressive discrepancy between Doppler-echocardiographic and invasive measurements of the transvalvular gradients in prosthetic valves. In a prospective study, we evaluated 11 out of 335 patients after aortic valve replacement who demonstrated an elevated transvalvular gradient over the prosthetic valve. Eight patients had a St. Jude medical prosthesis (19-23 mm), two patients had a Medtronic Hall prosthesis, and one patient a Björk-Shiley prosthesis. The maximal instantaneous gradient measured by Doppler-echocardiography was 74 +/- 15 mmHg, the mean gradient was 47 +/- 12 mmHg. The prosthetic orifice area calculated by the continuity equation using the left ventricular outflow tract diameter was 0.86 +/- 0.25 cm2, and that calculated by using the prosthetic ring diameter was 0.98 +/- 0.23 cm2. None of the patients had a severe aortic valve regurgitation. All patients were clinically asymptomatic. Transesophageal echocardiography and x-ray showed a normal prosthetic function. Angiographic examination performed in seven patients showed a peak-to-peak gradient of 26 +/- 9 mmHg, and demonstrated a marked discrepancy between Doppler-echocardiographic and invasive results. These results confirm the clinical limitations of Doppler echocardiography to distinguish between normal and disturbed prosthetic function.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

Added hospital stay due to wound infections following cardiac surgery.

To determine the prolongation of hospital stay due to postoperative wound infections following cardiac surgery, a prospective cohort study was performed by matching multiple control patients without infection to each infected patient (= case). Out of 22 cases, no patient died. No case had to be excluded from the matching process because of a lack of suitable control patients. The maximum number of controls per case was 10. The mean added stay was 12.2 days constituting a considerable prolongation of stay due to wound infection in cardiac surgery.

Adult↗

PubMed1992

[Non-cardiac complications after open heart surgery].

The most important complications after open heart surgery are neurological, gastrointestinal (GI), and renal complications. New neurological deficits may occur in 1%, and neuropsychiatric alterations may be observed in 40%. In 6% peripheral neurological damage occurs. Endoscopy in all patients whose clinical history suggests signs of gastric ulcer disease, and perioperative H2-blocking therapy are effective in reducing severe GI bleeding to 1%. Small-bowel ischemia is a rare but high risk complication. Hepatitis due to homologous blood transfusion is as low as 2%-3%. Postoperative renal insufficiency occurs in 1% needing hemodialysis. Good hemodynamic condition during and after surgery reduces the frequency of extracardiac complications as well as the reduction of use of homologous blood transfusions for open heart surgery.

Heart Diseases↗

PubMed1991

Electrocardiographic and antiarrhythmic effects of intravenous amiodarone: results of a prospective, placebo-controlled study.

The antiarrhythmic efficacy of intravenously administered amiodarone was examined in a prospective, randomized, placebo-controlled study that involved 77 patients after coronary artery bypass surgery. Amiodarone was given after surgery in a loading bolus of 300 mg for 2 hours followed by 1200 mg every 24 hours for 2 days and 900 mg every 24 hours for the next 2 days. Amiodarone suppressed both supraventricular and ventricular arrhythmias within 12 hours after the start of therapy. Particularly, the incidence of atrial fibrillation (5% vs 21% in the control group; p less than 0.05) and of nonsustained ventricular tachycardia (3% vs 16%; p less than 0.05) was reduced by amiodarone. Heart rate was slowed (p less than 0.001) and repolarization--as judged by JTc interval--was prolonged compared with the control group (p less than 0.01). In two patients, amiodarone infusion was stopped because of excessive QTc prolongation. No detrimental hemodynamic effects of the drug were observed. Thus the intravenous administration of amiodarone appears to be suitable for patients in whom rapid suppression of symptomatic supraventricular and ventricular arrhythmias is warranted in the presence of left ventricular dysfunction.

Aged↗

PubMed1991

Reduction of the risk of surgery for abdominal aortic aneurysms by extended coronary diagnostics and therapy.

The morbidity and mortality in the surgery of abdominal aortic aneurysms are essentially determined by the coronary risk profile of the patient. Preoperative coronary artery diagnostics with the potential consequence of a coronary revascularization as procedure before the aneurysmectomy seems to be mandatory to decrease the risk of treatment. Out of 223 patients treated at our institution for abdominal aortic aneurysm, 68 (30.5%) had to undergo extended cardiological diagnostic procedures, and 37 (16.6%) needed a coronary angiography; in 23 patients (10.3%) myocardial revascularization was performed prior to the aneurysmectomy. Since routinely performing this thorough investigation of the coronary risks, the mortality of surgery for aortic aneurysm has been clearly reduced.

Angioplasty, Balloon, Coronary↗

PubMed1991

[Histologic examinations of internal mammary artery, saphenous vein and aorta specimens collected during heart surgery].

133 patients with coronary heart disease were treated surgically. 60 patients had Internal Mammary Artery (IMA) grafting performed together with saphenous vein grafts (IMA group), another 70 patients had saphenous vein grafts only (SVG group). Material for histological examination was intraoperatively taken from saphenous vein and ascending aorta and in IMA group also from the distal part of internal mammary artery. The intensity of atherosclerosis was estimated with 5-grade scale from 0 to 4 (0-no atherosclerosis, 1-minimal, 2-insignificant, 3-moderate, 4-pronounced). To visualize and to assess the blood flow through the internal mammary artery Digital Subtraction Angiography (DSA) was performed between day 6 and day 8 postoperatively in the IMA group. Results obtained were correlated with the intensity of atherosclerosis estimated histologically and the numeric data were statistically analysed. In the IMA grafts mean atherosclerosis intensity was 0.94 which is the evidence of minimal atherosclerotic changes. In saphenous vein the corresponding value was in the IMA group 2.14 and in the SVG group 2.17, in aortic scraps 2.64 in the IMA group and 2.73 in the SVG group. Patients in the SVG group were average 8.4 years older than in the IMA group. The difference is statistically significant. Despite the age difference, the intensity of atherosclerosis was not statistically different in aortic and saphenous vein scraps. Among 63 patients in the IMA group in 31 patients (49.2%) no atherosclerosis was found during histological examination and in 32 patients (50.8%) changes ranged from minimal to moderate. There were no IMA grafts with the pronounced atherosclerosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

[Acute and chronic aortic rupture. Management without and with a protective bypass procedure].

The use of partial cardiopulmonary bypass in the surgery of thoracic aortic ruptures is still a matter of controversey. Since 1970, 38 patients with thoracic aortic rupture have been treated at our institution, 13 in a acute or subacute stage and 25 with traumatic aneurysm. Partial cardiopulmonary bypass was installed in 13 cases, and in 23 patients the "clamp and repair" technique was performed. Although there was no coherence between the occurrence of complications and the applied procedure, we prefer the use of partial cardiopulmonary bypass in view of the advantages in safe distal perfusion, direct retransfusion of blood, controlled decompression of the left heart, and the possibility to extend surgery to the aortic arch.

Adult↗