Search PubMed⌕ Search

Biomedical subjects

M Gawenda

Publications and source records attributed to M Gawenda.

At least 19 recordsLinked to original sources
PubMed2006

Hybrid-procedures for the treatment of thoracoabdominal aortic aneurysms and dissections.

AIM: The conventional open repair of thoracoabdominal aneurysms and dissections remains complex and demanding and is associated with significant morbidity and mortality. We present our experience of hybrid open and endovascular treatment of thoracoabdominal aneurysms and dissections. METHODS: Within an experience of 226 aortic stent-grafts between 1998 and April 2006, 6 of the patients (median age 60 years, range 35 to 68 years) with thoracoabdominal aneurysms (Crawford type I, II, III, and V) were treated with a combined endovascular and open surgical approach. Five men and one woman, with median aneurysm diameter of 75 mm (range 70-100 mm), received revascularization of the renal arteries, the superior mesenteric artery, and the coeliac trunk accomplished via transperitoneal bypass grafting. Aneurysmal exclusion was then performed by stent-graft deployment. RESULTS: The entire procedure was technically successful in all patients. The patients were discharged a median of 9 days after the operation, while the postoperative studies revealed the patency of the vessels and no evidence of type I endoleak or secondary rupture of the aneurysm. During follow up (1 to 22 months) spiral-CT scanning revealed distinct shrinkage of the aneurysm, no graft migration or endoleak and patency of all revascularised vessels, except one renal artery in two patients. No patient experienced any temporary or permanent neurological deficit, and no dialysis was necessary. CONCLUSION: The combined endovascular and open surgical approach is feasible, without cross clamping of the aorta and with minimized ischemia time for renal and visceral arteries, and seems to be an appropriate strategy for patients with a thoraco-abdominal aortic aneurysm or dissection.

Adult↗
PubMed2005

Radiation therapy induced modulation of wound healing at experimental vein graft anastomoses.

OBJECTIVES: The aim of this study was to investigate if radiation therapy (RT) favorably modulates wound healing at vein graft anastomoses. MATERIALS AND METHODS: Jugular vein grafts were sewn into carotid arteries in 32 rats which were randomly divided into two groups: RT (gamma source, 14 Gray, n=16) and control (C, sham irradiation, n=16). Grafts and adjacent arteries were analyzed at 2 (n=8) and 8 weeks (n=8) by histology, immunohistochemistry, and morphometry. RESULTS: Although, RT did not reduce the overall occurrence of intimal hyperplasia, the distribution differed. RT led to a reduction of intimal hyperplasia in arterial segments (median: C: 41.873 microm2; RT: 6.452 microm2, p < 0.0007). In contrast, RT augmented intimal hyperplasia in vein grafts (median: C: 30.287 microm2; RT: 90.455 microm2, p < 0.014). Vein graft diameters after RT were enlarged (median: C: 2.098 microm; RT: 3.381, p < 0.031). Over 80% of the cells were of mesenchymal origin in both groups. CONCLUSIONS: RT reduced intimal hyperplasia in arterial segments. However, RT led to graft dilatation and increased intimal hyperplasia in vein grafts. RT did not favorably modulate the vascular wound healing response in this model.

Anastomosis, Surgical↗
PubMed2005

Differentiated treatment of aneurysms of the extracranial carotid artery.

AIM: Aim of the study is to illustrate current therapeutic options for aneurysms of the extracranial carotid artery. METHODS: From 1987 until 2003 14 patients (average age: 60 years) with an aneurysm of the extracranial internal carotid artery were treated. The aneurysm diameter ranged from 5 mm to 60 mm. Thirteen patients underwent elective surgery. One patient was operated upon because of acute severe cervical bleeding. RESULTS: Most patients (10/14) presented with an asymptomatic pulsatile cervical mass. The aneurysm was diagnosed 3 times during carotid angiography. The underlying etiology was atherosclerosis in 10 patients. In 3 cases the aneurysm was considered mycotic. Ten aneurysms were localized at the carotid bifurcation whereas 2 each were found in the retrostyloideal region and at the base of the skull. Vascular continuity could be restored in 10 patients while in 3 the carotid artery had to be occluded (twice surgically and once radiologically). The final patient underwent stent insertion for post-traumatic distal aneurysm. In 5 patients perioperative neurological complications were noted which persisted in a single patient (dysphagia due to a lesion of the hypoglossus nerve). All hemispheric complications recovered completely. During follow-up (median 48 months ranging from 3 to 103 months), 1 patient died of unrelated cause. Another patient developed a contralateral ischemic insult. CONCLUSIONS: When adjusting treatment to the various etiological conditions and localizations, aneurysms of the extracranial carotid artery can be managed with a low complication rate and satisfying long-term results. However, success mainly depends on the timely diagnosis and availability of a range of surgical and radiological therapeutical options.

Aneurysm↗
PubMed2005

Device-specific outcomes with endografts for thoracic aortic aneurysms.

For the endovascular therapy of abdominal aortic aneurysm an increasing number of publications deal with the subject of device-related outcome and aneurysm sac behaviour. The present study was designed to investigate whether, and to what extent, aneurysm sac behaviour of thoracic aortic aneurysms and perioperative outcome is influenced by the different types of stent grafts. Bibliographic search and analysis was performed. A systematic MEDLINE search on thoracic aortic aneurysms produced a total of 2,884 references with abstracts between 1990 and 2004. Restricted by using the additional terms of ''descending'' and ''stent graft'' the result condensed to 152 papers. Each reference was analyzed according to predetermined criteria. The majority of articles were published in the English language. Two publications summarized the results of nation-wide or continental registers of endoluminally treated patients with descending aortic dissections or thoracic aortic disease. Several series were partial and/or updated reports from the same authors and/or on the same patients. A total of 48 centres reported about the endovascular treatment of more than 3,000 patients with pathological thoracic aortic entities (Approximately 1,650 degenerative thoracic aortic aneurysms, Approximately 1,000 aortic dissections, Approximately 400 miscellaneous aortic pathologies). The heterogeneity among the series precluded any relevant comparison. Only 4 centres have presented study groups of more than 100 treated patients, but 3 series contained several treated aortic pathologies. Without a differentiation to the underlying pathology, the bibliographic research documented a rate of technical success in a range of 76% to 100%. Summarizing the data of par-procedural and in-hospital mortality the bibliographic research documented a mortality rate of 6.8% for all reported procedures. The rate of paraplegia for all procedures was 1.7%. In conclusion the presented bibliographic search and analysis demonstrated the technical feasibility of the endoluminal stent grafting of a great variety of thoracic aortic pathologies. The short-term results are promising, but data of mid-term results are rare and long-term results are missing. Moreover, the question about the influence of different types of stent grafts on the outcome can not be answered.

Aortic Dissection↗
PubMed2004

Endotension is influenced by wall compliance in a latex aneurysm model.

OBJECTIVES: Even though endovascular aneurysm repair (EVAR) creates a closed chamber except for patent branches, the intra-sac pressure is never zero. This study was designed to investigate whether, and to what extent, aneurysm wall compliance influences intra-sac pressure. DESIGN: In vitro experimental study. METHODS: Aneurysm models with six and 12 latex layers were produced, resulting in elastic and stiff circumferential compliance (3.5 +/- 0.5 and 0.9 +/- 0.3%/100 mmHg, respectively). The models with an 18 mm internal neck and maximum aneurysm diameter of 60 mm were inserted into an in vitro circulation system. The systemic mean pressure (SPmean) was varied from 50 to 120 mmHg. After the aneurysm was excluded with a knitted polyethylene graft, aneurysm sac mean pressure (ASPmean) and aneurysm sac pulse pressure (ASPpulse) were measured. Data are presented as mean +/- SD. Statistics were performed using repeated measurements of variance; p<0.05 was considered significant. RESULTS: In the model EVAR created a closed chamber without endoleak, but with an aneurysm sac pressure related to wall compliance. In the elastic aneurysm model with six latex coats the aneurysm sac mean pressure (ASPmean) and the aneurysm sac pulse pressure (ASPpulse) at all systemic pressures were significantly lower than they were in the stiffer model with 12 latex coats (p<0.05). At a SPmean of 90 mmHg, the ASPmean was 21.0 +/- 0.9 mmHg (six latex coats) and 26.0 +/- 0.2 mmHg (12 latex coats) (p<0.05), the ASPpulse was 5.7 +/- 0.2 mmHg (six latex coats) and 8.8 +/- 0.3 mmHg (12 latex coats) (p<0.05). CONCLUSIONS: This in vitro model demonstrated that the aneurysm sac mean pressure (ASPmean) and the aneurysm sac pulse pressure (ASPpulse) were significantly influenced by the compliance of the aneurysm wall. These data highlight the need for further studies regarding endotension.

Aortic Aneurysm, Abdominal↗
PubMed2004

Prediction of cerebral ischemic tolerance during carotid cross-clamping by angiographic criteria.

OBJECTIVE: To evaluate the prognostic value of angiographic criteria and internal carotid artery (ICA) stump pressure for shunt placement in carotid surgery under local anaesthesia. DESIGN: Prospective clinical trial at a university hospital. MATERIALS AND METHODS: In 120 patients a cerebral angiography was initiated before undergoing carotid surgery. Seventy-five percent of the patients were neurologically asymptomatic, 13% had transient ischaemic attacks and 12% suffered from previous strokes. The operation was exclusively performed under local anaesthesia and prior to cross-clamping the ICA stump-pressure was measured. A shunt was inserted only if hemispheric symptoms or unconsciousness occurred independent of the angiographic findings or stump pressure. RESULTS: In 23% (27/120) a shunt became necessary and significantly (p<0.001) more often when there was a cross-flow towards the contralateral hemisphere (12/20=60%) or if the contralateral ICA was occluded (9/13=69%). The sensitivity for not needing a shunt in case of cross-flow towards the side of operation was 91% (52/57) whereas the specificity was 35% (22/63). ICA stump-pressure was significantly reduced in patients requiring a shunt (31 mmHg) compared to those not needing a shunt (53 mmHg) (p<0.001), but no definitive threshold value was found determining the need for shunting. Intraoperatively, no persistent neurological complication developed. CONCLUSIONS: Angiographic cross-flow was a good, but not perfect predictor for the need of an intraoperative shunt.

Aged↗
PubMed2004

Modulation of human adventitial fibroblast function by photodynamic therapy of collagen matrix.

OBJECTIVES: Photodynamic therapy (PDT) is a promising strategy to limit restenosis. PDT depletes the resident cells from the vessel wall without adventitial cell ingrowth. This study was undertaken to further explore the mechanisms by which PDT of matrix acts on key mechanisms in the development of restenosis. MATERIALS AND METHODS: Control and PDT-treated collagen type-I matrix gels were prepared. Thereafter, untreated human fibroblasts were seeded on matrix gels (n=12). Fibroblast proliferation and invasive migration were quantified by calibrated phase contrast microscopy. Fibroblast bFGF and TGF-beta1 mRNA expression were analyzed using a quantitative real-time reverse transcription polymerase chain reaction. RESULTS: Fibroblast proliferation on PDT-treated matrix gels was reduced by 30 and 76% after 3 and 7 days, respectively (3 days: P</=0.01, 7 days: P< or =0.001). PDT of matrix gels led to a 47% reduction of migration after 3 days and 51% after 7 days (P< or =0.001). PDT led to a 77% reduction of fibroblast TGF-beta1 mRNA (P< or =0.02) and to a 79% reduction of bFGF mRNA (P< or =0.03). CONCLUSIONS: PDT of matrix-induced reduction of bFGF and TGF-beta1 mRNA levels may be important mechanisms of reducing fibroblast proliferation and invasive migration and thus the development of restenosis. These newly identified mechanisms highlight PDT's pleiotropic effects on the vessel wall and its potential clinical value.

Arterial Occlusive Diseases↗
PubMed2003

Endotension as a result of pressure transmission through the graft following endovascular aneurysm repair--an in vitro study.

BACKGROUND: endovascular aneurysm repair (EVAR) significantly reduces, but does not abolish aneurysm sac pressure, possibly because of trans-fabric transmission. OBJECTIVE: to investigate how blood pressure is transmitted through different types of grafts into the aneurysm sac. DESIGN: experimental study, in vitro. METHODS: a latex aneurysm was inserted into an in vitro circulation model. The systemic mean pressure (SPmean) was varied from 50 to 120 mmHg. The grafts used for aneurysm exclusion were: thin wall polyethylene (PE), thick wall polyethylene (PE) and thin wall ePTFE. Mean aneurysm sac pressure (ASPmean) was measured, as was pulse pressure (ASPpulse). RESULTS: at an SPmean of 70 mmHg, the ASPmean was 34 +/- 0.8 mmHg (polyethylene knitted, thick wall), 30 +/- 1.0 mmHg (polyethylene woven, thin wall), and 17 +/- 0.6 mmHg (thin wall ePTFE). The ASPmean increased with SPmean, the relationship depending on the graft material. Stiffer grafts were associated with lower ASPmean and ASPpulse (p<0.001). CONCLUSIONS: the relationship between aneurysm sac mean pressure and systemic pressure (SP) depends on the graft material. These data highlights the need for further studies regarding endotension.

Aortic Aneurysm, Abdominal↗
PubMed2003

Endotension leading to aneurysm sac rupture following open repair of abdominal aortic aneurysm.

Endotension leading to enlargement of the aneurysm sac following the endoluminal grafting is still handled as an exclusive phenomenon of the endovascular aneurysm repair (EVAR). We report on a case with aneurysm sac enlargement caused by endotension leading to aneurysm rupture after conventional, open aneurysm repair, a so far not described complication. In a 74-year-old patient, following open surgical standard resection and reconstruction of an abdominal aortic aneurysm, a routinely performed abdominal ultra-sonography demonstrated a slowly growing enlargement of the peri-prosthetic aneurysm sac without endoleak. During the pre-operative work-up of the cardiac and pulmonary risk profiles, he complained of abdominal pain and back pain. Control CT revealed contrast inside the aneurysm sac as well as in the right-sided retroperitoneum. At the emergency operation a retroperitoneal haematoma was noticed. Opening the ballooned aneurysm sac, a fresh haematoma was also found. Lifting up the prosthesis, back bleeding at the dorsal circumference of the proximal anastomosis was confirmed due to a 2 cm long disruption of the anastomosis. In patients who present with abdominal or back pain after conventional surgery of an abdominal aortic aneurysm, a contrast CT should be performed to exclude an endoleak as well as other pathologies. The enlargement of the aneurysm sac without endoleak could be interpreted as endotension, with the consequence of urgent re-operation to prevent rupture.

Aged↗
PubMed2003

[Internal carotid artery dissection at the carotid canal after blunt trauma: case report of endovascular repair and literature review].

Symptomatic dissecting aneurysms of the extracranial internal carotid artery after blunt trauma are not frequent. Medical treatment of these lesions can be ineffective and surgical options present high morbidity. We describe a case successfully treated with endovascular therapy, using a self-expanding stent. The advantages of the endovascular treatment are outlined, the literature on carotid artery injuries by blunt trauma and management strategies are reviewed.

Adult↗
PubMed2003

Current indication for endovascular treatment of thoracic aneurysms.

The morbidity and mortality for open treatment of thoracic aortic aneurysms have declined over the years, but it is still a major clinical problem. The reason for the mortality is in almost 50% of the cases cardiac failure. Endoluminal treatment of abdominal aortic aneurysm is widely distributed and with promising results, although not as free from complications as expected 10 years ago. This technique has also been adopted for the thoracic aortic aneurysm as the trauma is much less than in open surgery. In our own personal series no specific workup for coronary heart disease has been made and the mortality of stentgrafting of the thoracic aorta was 2.4%. A survey of the world literature, including elective and acute dissections and aneurysms revealed 642 patients treated with stentgraft with a mortality of 6.2%, although no cardiologic work up had been performed. These numbers compete well with those of open surgery, but a systematic prospective comparison would be needed in order to state the real mortality in both groups.

Adult↗
PubMed2002

Intra-aneurysm sac pressure--the holy grail of endoluminal grafting of AAA.

OBJECTIVES: To relate intra-aneurysm sac pressure during endoluminal AAA repair to early and late endoleak, as well as to the aneurysm size upon follow-up. DESIGN: Prospective clinical investigation. METHODS AND PATIENTS: In 46 patients who had their AAAs treated by a stent graft (group I), intra-operative pressure measurement was performed (aorta uni-iliac stent grafts: 25 cases, bifurcated stent grafts: 21 cases). In 18 patients with open repair (group II) flow in the inferior mesenteric artery, and the pressure in the aneurysm sac was measured, before and after aortic and iliac cross clamping. Values are given in median with range. RESULTS: In group I, complete exclusion of AAA (no endoleak on intra-operative control angiogram) resulted in a statistically significant decrease in mean sac pressure from 74 (55-101) to 47 (4-104) mmHg. Pulse pressure reduced from 67 (34-103) to 8 (0-74) mmHg. In 11 patients a proximal type I endoleak was sealed by balloon modeling, after which the mean sac pressure reduced from 63 (14-91) to 52 (4-74) mmHg (n.s. versus patients with primary seal). Intra-operative pressure did not correlate with change in AAA diameter during twelve months follow-up. In group II, cross clamping of the proximal aorta significantly reduced mean sac pressure to 32 (21-55) mmHg, and the pulse pressure to 0 (0-13) mmHg (p < 0.05). Subsequent cross clamping of the iliac arteries did not significantly change the pressures. CONCLUSIONS: Measurement of intra-aneurysm sac pressure can help to detect and treat endoleaks during endoluminal grafting. However, the intra-operative sac pressure did not predict the fate of aneurysm during follow up. Compared to open repair of AAA, the sac pressure after endoluminal grafting remains significantly higher, in relation to pulse pressure.

Aged↗
PubMed2002

[Intravascular ultrasound thrombolysis for recanalization of peripheral arteries: evaluation of an in vitro model and results of a pilot-study].

OBJECTIVES: To evaluate the effectiveness of ultrasound thrombolysis in vitro in comparison with thrombectomy, and in vivo as a pilot-study for the treatment of thrombotic occlusions of peripheral arteries. METHODS: Under standardized conditions, one-day-old and five-day-old thrombi of whole blood, thrombin-induced thrombi and old organized thrombi of human blood were treated with ultrasound thrombolysis and Amplatz thrombectomy device (ATD). Four patients with arterial occlusive disease of Fontaine stage IIb-III underwent intraarterial ultrasound-thrombolysis, applied to long segmental occlusions of the superficial femoral or iliac artery ranging in duration from three days to one year. RESULTS: The weight of the thrombi after ultrasound thrombolysis was 1.5 g +/- 0.53 (ATD: 0 g) compared to 3.65 g +/- 0.34 without treatment, with more weight reduction in five-day-old thrombi than in one-day-old thrombi. In vivo, partial recanalization was achieved in a three-day-old femoral occlusion. There was no effect in the other three patients. Urokinase thrombolysis with subsequent PTA and stenting resulted in complete recanalization in three patients. CONCLUSIONS: Ultrasound thrombolysis in vitro was significantly less effective than ATD. The results of ultrasound thrombolysis were influenced by the age of the thrombus and its in vitro formation. Intravascular ultrasound thrombolysis alone was insufficient to treat occluded peripheral arteries in vivo.

Aged↗
PubMed2002

Vascular restenosis. Basic science and clinical implications.

Cardiovascular interventions to correct arterial occlusive disease have excellent short-term results, but long-term patency is still seriously compromised by the development of restenosis. This review will provide a portrait of the mechanisms following vascular injury, define the clinical scope of the problem and outline developments of different therapeutical strategies to prevent restenosis.

Angioplasty, Balloon↗
PubMed2002

Stent-graft replacement of chronic traumatic aneurysm of the thoracic aorta after blunt chest trauma.

Chronic traumatic aneurysm of the thoracic aorta is an unusual occurrence. Open-chest surgery for repair of chronic traumatic aneurysms results in mortality rate of 5-18%, and a morbidity rate of 11-50% also. The evolution of endovascular technology offers the promise of a new, less invasive method to achieve aneurysm exclusion. A case of chronic traumatic aneurysm of the near isthmus thoracic aorta discovered on a chest X-ray and evaluated with chest computed tomographic scanning is presented. Stent-grafting procedure is described. Stent-grafting in chronic traumatic aneurysm of the thoracic aorta seems to be a viable minimal invasive therapeutic option for traumatic rupture of the aortic isthmus.

Accidents, Traffic↗
PubMed2002

Stent jail of the renal arteries in stent graft exclusion of AAA. An in vitro study of 3 different stent types.

BACKGROUND: The success of endoluminal stent grafts (ELG) is critically dependent on secure proximal fixation of the graft. Different types of stent grafts with uncovered proximal portions for transrenal fixation are obtainable. The present in vitro study was designed to elucidate how the flow parameters were altered by stent jail of the renal arteries with respect to different stent design. METHODS: The experiments were performed in an in vitro pulsatile circulation model. An aortic segment with bilateral side branches (like renal arteries) constructed of an ePTFE graft was perfused in the circulation model. The flow measurements were based on the ultrasound transit-time method. By varying the frequency from 30 to 100 bpm the flow parameters were altered and recorded continuously. Renal stent jailing was carried out using different stent types: Gianturco-Z-Stent, Palmaz-Stent, Powerlink Endologix. RESULTS: The flow in the aortic model increased from 1100 ml per minute to 3330 ml per minute depending on the pump frequency. In the control group without stent jail the renal flow was measured between 240 ml per minute up to 810 ml per minute. The ratio of renal flow was between 0.22 and 0.24 of the aortic flow. In the Palmaz group the ratio was between 0.21 and 0.24, in the Gianturco group between 0.23 and 0.25, and in the Powerlink group between 0.24 and 0.25 (unpaired-"t"-test: n.s.). CONCLUSIONS: The covering of the renal arteries and/ or superior mesenteric artery in case of long bared proximal stent raises the question whether the stent jail may result in flow reduction in the arteries covered or not. The present in vitro study demonstrated that the flow in the renal arteries is not decreased by these stent jails.

Aortic Aneurysm, Abdominal↗