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Biomedical subjects

F Redha

Publications and source records attributed to F Redha.

17 recordsLinked to original sources
PubMed1996

Ultrasonic-pathologic comparison of postangioplasty myointimal hyperplasia and primary atheroma of the superficial femoral artery.

The purpose of this study was to characterize postangioplasty myointimal hyperplasia as compared to primary atheroma of superficial femoral arteries using color-coded duplex sonography (CCD), and to correlate sonographic findings with the histopathology of samples obtained from these lesions by catheter atherectomy (Redha-cut device). Preinterventionally, homogeneity, echogeneity, and the surface of plaques were described using CCD in nine cases with secondary stenoses after percutaneous transluminal angioplasty and in seven cases with primary atheroma. Myointimal hyperplasia of femoral restenoses showed a homogeneous (7 of 9 vs. 1 of 7) and hypoechogenic (7 of 9 vs. 0 of 7) wall thickening compared to primary atheromas (p < 0.05). Primary atherosclerotic plaques showed a rather heterogeneous, hypo- and hyperechogenic ultrasonic appearance with or without echo shadowing in six of seven cases. The surface of restenoses was more often regular than that of primary atherosclerotic lesions, but this finding did not reach statistical significance (6 of 9 vs. 2 of 7, p = 0.14). Thrombotic material appeared homogeneous and hypoechogenic in three of five cases and could not be discriminated from intimal hyperplasia. In summary, postangioplasty intimal hyperplasia is characterised by a hypoechogenic, homogeneous, rather regularly confined vessel wall thickening and can be differentiated from primary atheroma at CCD.

Aged↗
PubMed1996

[Initial clinical results in the treatment of peripheral arterial occlusive diseases using new percutaneous atherectomy equipment (REDHA-CUT)].

In 11 female and 13 male patients 29 symptomatic femoropopliteal occlusions were treated with a novel intraluminal endarterectomy device (REDHA-CUT). The pre-existing stenoses (71 +/- 9%) could be reduced to 29 +/- 18% (means +/- s.d.). The arteriectomy procedure with this device took on average 5 +/- 3 min. Neither perforations nor dissections nor distal embolisms or any other complications were observed. In comparison with other percutaneous transluminal angioplasty procedures the clinical use of the novel REDHA-CUT device is safe, simple and fast and allows for the retrieval of plaque biopsies.

Aged↗
PubMed1995

Does acute pancreatitis progress to chronic pancreatitis? A microvascular pancreatitis model in the rat.

Ischemia as a causative factor for acute pancreatitis has been discussed for decades but has only recently gained wider acceptance. Chronic pancreatitis, however, has rarely been attributed to ischemic injury. While experimental evidence is available for the ischemic pathogenesis of acute pancreatitis, no studies have been reported about pancreatic ischemia as a single cause of chronic pancreatitis. Also, the progression from acute to chronic pancreatitis has been a very controversial issue. To address both questions we have injected polystyrene microspheres of 20-microns diameter into the pancreatic branches of the splenic artery of 36 rats. Thirteen more rats were sham operated and injected with saline. The animals were killed at 1, 2, 3, and 9 weeks after operation and macroscopically and histologically examined, and serum alpha-amylase and weight gain were determined. For the pancreas the following parameters were assessed using a score from 0 (no change) to 4 (severe change): atrophy, hemorrhage, edema, fat necrosis, acinar necrosis, polymorphonuclear infiltration, mononuclear infiltration, interstitial fibrosis, and ductal changes. While no difference between control and experiment was observed for serum alpha-amylase, weight gain, edema, and hemorrhage, persistent differences were evident for the parameters characteristic of chronic pancreatitis, most significantly for interstitial fibrosis, ductal changes, mononuclear infiltration, acinar necrosis, and atrophy. No spontaneous deaths occurred. The severity of the lesions remained stationary after the first week. Our work shows for the first time that pancreatic ischemia by microvascular hypoperfusion can cause histopathologic changes characteristic of chronic pancreatitis and that these changes follow acute necrotizing pancreatitis.

Acute Disease↗
PubMed1995

Morphological and functional changes in canine kidneys following extracorporeal shock-wave treatment.

Extracorporeal shock-wave lithotripsy (ESWL) has rapidly become established worldwide as a routine method for treatment of nephro- and ureterolithiasis. Although initial studies showed no tissue-damaging effect by the shock waves, we found, in an animal experiment using canine kidneys, that the ESWL-induced damage to the renal parenchyma is more marked than originally assumed. The damage is limited to the area that was focused on, and heals relatively rapidly by connective tissue encapsulation with final cicatrisation without any further residual effects being observed up to the present. This parenchymal damage is probably also the cause of the macrohematuria that is always observed during therapy. The resulting tissue damage is not extensive enough to cause a demonstrable reduction of function as measured by the usual methods (serum creatinine, creatinine clearance, isotopy renography, i.v. urography). In serum we observed a transient decrease of calcium, an immediate increase of lactate-dehydrogenase, transaminases (SGOT and SGPT) and a delayed increase of alkaline phosphates. Creatinine, blood urea nitrogen, sodium, potassium and amylase remained within normal limits. In urine, a decrease of creatinine and an increase of glucose excretion were noted. We believe that these changes represent a relatively mild and transient damage of renal cells and do not reflect the occasionally heavy morphological changes observed after shock-wave exposure. The main clinical complication is the large subcapsular hematoma which, according to the present knowledge, could well result from a lesion of the larger peripheral vessels. Damage to other organs such as subserous colonic and small bowel hematomata are to be expected although they do not lead to clinical symptoms.

Animals↗
PubMed1994

[Do resorbable suture materials permit safe vascular anastomoses?].

Vascular surgery in growing organisms is still problematic. Especially in surgical therapy of coarctation of the aorta, high restenose rates are documented if non-absorbable polypropylene and running suture technique ist used. Theoretically, absorbable suture material allows a running suture technique with less restenose rates. Our study compares absorbable (polyglyconat and polydioxanon) with non-absorbable (polypropylene) suture material for repair of aorta in growing dogs. Anastomoses performed with absorbable suture material show after one year very good functional results without any local complications. In conclusion we can say that absorbable suture material allows formation of safety vascular anastomoses and doesn't impair growth of anastomoses.

Age Factors↗
PubMed1993

[Myocardial protection: is retrograde equal to antegrade perfusion?].

The adequacy of retrograde delivery of cardioplegic solution to the right ventricle ist controversial. To evaluate this issue, we excised the plegic heart in 11 bovine experiments and infused an India ink solution (10 ml of India ink in 300 ml NaCl 0.9%) into the coronary sinus (n = 7) at a pressure of 60 cm H2O and into the aortic root (n = 4) at a pressure of 120 cm H2O. After fixation, the ventricles were cut in 11 transversal slices. The portion of coloured (= perfused) ventricular myocardium was calculated with computer-aided morphometric analysis. With antegrade infusion, 95 +/- 5% (mean +/- standard deviation) of the left ventricular volume (left ventricular free wall plus interventricular septum) was stained, with retrograde infusion 94 +/- 3%. Perfusion of the right ventricle was significantly lower with retrograde infusion (antegrade infusion 93 +/- 8%, retrograde 45 +/- 13%, p < 0.001), especially in the basal segments (basal vs. apical: 16 +/- 26% vs. 82 +/- 5%, p < 0.001). The adequate delivery of retrograde infusion to the left ventricle and septum allows good left ventricular myocardial protection with retrograde cardioplegia. Because the retrograde delivery to the right ventricle is markedly inadequate and nonuniform, the quality of right ventricular protection with retrograde cardioplegia has to be questioned.

Animals↗
PubMed1992

[A new intraluminal endarterectomy instrument].

In 40 human cadaver arteries endarterectomy was performed using a new intravascular device. The system and technique are described. According to our preliminary laboratory experiences the new device proofed to be save and effective. It will allow us to approach more complex lesions not ideal for balloon angioplasty. Clinical investigations will be performed in the near future.

Arteriosclerosis↗
PubMed1992

[Acute pancreatitis in the rat following experimental microembolism with cholesterol crystals].

Several case reports exist which demonstrate cholesterol crystals to be the cause of acute pancreatitis in humans. The crystals have been found intravascularly in the pancreas and at least in one case the origin of the crystals was known. We have undertaken to experimentally reproduce this pathogenetic mechanism in the rat. 30 rats were subjected to the following procedures: under anaesthesia the splenic artery was distally ligated and proximally cannulated; 16 control animals were injected via the cannula with saline (8 rats), particle free cholesterol saturated physiologic saline (3 rats) or nothing (5 rats). 14 rats were injected with ca. 400 microliters of a dilute suspension of cholesterol crystals of 5-40 microns diameter in cholesterol saturated physiologic saline. The abdomen was closed and after 24 h all animals were killed. Acute pancreatitis was diagnosed in all animals that received cholesterol microcrystals and in none of the controls. The diagnosis was based on macroscopic and histological findings. Acute pancreatitis was of focal, disseminated, necrotic type with oedema and moderate haemorrhage and fat necrosis. Only those parts of the pancreas were affected which were supplied by branches of the distal splenic artery used for retrograde injections of cholesterol crystals. This model supports the notion that microembolic or microthrombotic events play a pivotal role in the pathogenesis of spontaneous acute pancreatitis.

Acute Disease↗
PubMed1991

Arterial stent placement with use of the Wallstent: midterm results of clinical experience.

Self-expandable stents of the Wallstent type were used in 26 iliac and 15 femoropopliteal artery lesions of 31 patients to treat stenoses or occlusions. The indications were confined to complex lesions, including residual stenoses and dissections after percutaneous procedures or previous surgery in the iliac artery lesions, and long-segment (mean, 13.5 cm) occlusions with inadequate response to percutaneous recanalization in the femoropopliteal artery lesions. In the iliac artery group, after stent placement, 96% of the lesions were patent at a mean follow-up of 16 months (range, 6-30 months). In the femoropopliteal artery group, of 11 patients available for follow-up, only six had patent stents at 7-26 months (mean, 20 months). Four of these six patients required one to three secondary interventions. Self-expanding endoprostheses are of great value in complex iliac artery lesions where simple balloon dilation is insufficient. Stent placement for long femoral artery lesions should be performed with utmost reserve, and the extent of stent placement should be as short as possible.

Aged↗
PubMed1990

Superior hemodynamics in left heart bypass without systemic heparinization.

Open-chest left heart bypass was performed in 10 canine experiments (30 +/- 9 kg) by a servo controlled roller pump for 6 h at a pump flow of 50 ml/min per kg bodyweight. The surfaces of the tubing sets were either standard (with systemic heparinization) or with end-point attached heparin (no systemic heparin). Besides continuous monitoring of hemodynamics, a standard battery of blood samples was taken before bypass, after 10 min and every hour thereafter. There is no evidence of increased fibrin production in the group with end-point attached heparin surfaces perfused without systemic heparinization. Superior hemodynamics in left heart bypass performed without systemic heparinization appear to be due to improved hemostasis, reduced blood loss and therefore reduced transfusion requirements. Left heart bypass with heparin-coated equipment has been successfully used for resection of a thoracoabdominal aneurysm in six patients.

Animals↗
PubMed1990

Injection of microspheres into pancreatic arteries causes acute hemorrhagic pancreatitis in the rat: a new animal model.

Alterations in the vascular bed of the pancreas or disturbances of the blood coagulation system are mostly considered to be sequelae of acute pancreatitis, but it seems that impairment of the pancreatic blood supply can per se lead to acute hemorrhagic pancreatitis. To test this hypothesis with a new animal model, we injected 20 microns polystyrene microspheres retrogradely into the distal splenic artery of rats, thus incompletely blocking blood perfusion in the splenic portion of the pancreas. Eight of eight rats (100%) subjected to microsphere injection developed acute hemorrhagic pancreatitis by 27 h after surgery, when they were killed, but none of the six sham-operated control animals (0%) showed macroscopic signs of pancreatitis. Blood amylase levels at death were 3,087 +/- 650 I.U./L (mean +/- SEM) and the histologic severity score for pancreatitis was 10.8 +/- 1.0 (mean +/- SEM), whereas in the six control rats amylase levels were 1,375 +/- 158 I.U./L and the histology score was only 1.7 +/- 1.0. The result is, with p less than 0.0005, highly significant (chi 2 analysis) and shows that acute experimental pancreatitis can indeed be induced by partially blocking the arterial blood supply within the organ.

Acute Disease↗
PubMed1989

Cyclosporine A impairs wound healing of ureterocystoneostomy in rats. Scanning electron microscopic examination.

The effect of cyclosporine A (CsA), an immunosuppressive agent used in transplantation, on wound healing following microsurgical neoimplantation of a ureter in the bladder of 63 SIV ZUR rats was examined morphologically using the light and scanning electron microscopes and functionally by radiography. Following ureterocystoneostomy (UCN) on the right side, the animals in Group I (control group) received 1.0 ml CsA solvent (0.1 g ethanol and 0.3 g intralipid) per day. Group II received 12.5 mg/kg/day CsA and Group III 17.5 mg/kg/day CsA. All drugs were administered i.p. A third of the animals in each group were reoperated 7, 14 or 28 days after UCN. At these time intervals, there were no radiologically demonstrable differences in the operated side. Examination under the scanning electron microscope indicated delayed restitution of epithelium in the bladder for rats which had received CsA as compared to the control group. In the area of the UCN, CsA caused dose-independent retardation of the regenerative hyperplasia associated with wound healing (Group I: max. 7 days after UCN: Group II and Group III, max. 14 days after UCN). Hyperplastic areas had ropy microridges and uniform short microvilli. Where the hyperplasia exhibited nodular and papillary formation, also histologically more evident under CsA, occasional epithelial cells had pleomorphic microvilli on their luminal surface. Unlike other known premalignant changes of this kind, the frequent occurrence of pleomorphic microvilli under CsA was reversible. In general, CsA led to dose-unrelated protraction of UCN wound healing with no lasting functional disturbance in rats.

Animals↗
PubMed1988

Morphological changes in canine kidneys following extra-corporeal shock wave treatment.

Extracorporal shock wave lithotripsy has rapidly become established world wide as a routine method for treatment of nephro- and ureterolithiasis. Although initial studies showed no tissue damaging effect by the shock waves, we found in an animal experiment using canine kidneys, the ESWL induced damage to the renal parenchyma is more marked than originally assumed. The damage is limited to the area that was focused on, and heals relatively rapidly by connective tissue encapsulation with final cicatrisation without any further residual effects being observed until now. This parenchymal damage is probably also the cause of the macrohaematuria that is always observed during therapy. The resulting tissue damage is not extensive enough to cause demonstrable reduction of function as measured by the usual methods (serum creatinine, creatinine clearance, isotopy renography, i/v-urography). The main clinical complication is the large subcapsular haematoma which, according to present knowledge, could well result from a lesion of the larger peripheral vessels. Damage to other organs such as subserous colonic and small bowel haematomata are to be expected although they do not lead to clinical symptoms.

Animals↗
PubMed1988

Performance characteristics of a disposable ventricle assist device.

A disposable ventricle assist device (VAD) including atrium, ventricle and trileaflet valves (all polyurethane) can be driven either a) by its original self adjusting drive unit (ABIOMED BVS 5000) or b) by a standard intra-aortic balloon pump console (DATASCOPE). Maximum flow in vitro was 4.3 l/min with the original drive console versus 9.2 l/min for activation with the intra-aortic balloon pump console. Performance characteristics of the VAD were evaluated in 11 bovine experiments. In vivo left ventricular assist for up to 24 hours with VAD and either original drive console or standard intra-aortic balloon pump console showed superior flow on activation with the intra-aortic balloon pump console (5.3 +/- 1.7 l/min) versus original drive console (3.5 +/- 0.5 l/min). After 6 hours of assist (before any transfusions) there was no significant difference in classic parameters for evaluation of blood trauma such as plasma hemoglobin production, LDH production and platelet depletion. We conclude that VAD is extremely simple to use. Activation by an intra-aortic balloon pump console enables significant increase of VAD-output without detectable increase of blood trauma. Successful weaning of VAD activated with standard intra-aortic balloon pump console was possible in a first clinical application.

Aortic Valve Insufficiency↗
PubMedDate not supplied

Neointima formation following arterial placement of self-expanding stents of different radial force: experimental results.

PURPOSE: Radial force delivered by self-expanding stents has been discussed as a factor affecting thickness of neointima formation. METHODS: Two types of Wallstents were studied experimentally in vitro and in vivo. Due to an altered braiding angle of the stent filaments, one stent type (LS type) delivers half the radial force to the vascular wall than the conventional type. The radial force was evaluated in a compression-expansion test which related changes in stent length to the compressing force. Fourteen LS and 16 conventional stents were implanted into 15 femoropopliteal arteries of 10 dogs. Autopsy was performed after 4 weeks (14 stents) or 6 months (16 stents). RESULTS: All stents remained patent over the follow-up period with no evidence of stenosis. Neointimal overgrowth was complete and smooth in all. Medial atrophy was a constant finding after placement of both types. Neointimal thickness did not exceed 100 microns after 4 weeks and 6 months and did not significantly differ between LS stents and conventional stents. CONCLUSION: It is concluded that in normal dogs self-expanding stents of the Wallstent type do not induce neointimal buildup that exceeds 100 microns in the femoropopliteal artery. A reduced radial force was not found to result in reduced neointima formation.

Animals↗