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Biomedical subjects

S Karacagil

Publications and source records attributed to S Karacagil.

At least 37 records · Page 2Linked to original sources

Method for dissection of mesenteric metastases in mid-gut carcinoid tumors.

With adequate medical management the midgut carcinoid tumor generally is an indolent malignancy associated with substantial life expectancy and appreciable life quality, even in the presence of liver metastases and significant tumor burden. Abdominal complications may occur in this entity of carcinoids owing to entrapment of intestines and encasement of mesenteric vessels by mesenteric metastases and associated marked mesenteric fibrosis. This may be the cause of abdominal pain, disabling diarrhea, weight loss to the extent of malnutrition, and eventually the risk of death with acute or chronic intestinal obstruction or intestinal gangrene. Operative removal of the mesentericointestinal lesion is often indicated to prevent or treat these complications but may be technically difficult when mesenteric metastases extend in the vicinity of major vessels in the mesenteric root. At laparotomy 56 patients with advanced midgut carcinoids underwent removal of the mesenteric tumor with a method for preserving the mesenteric vessels. This was feasible by mobilizing and releasing the right colon and mesenteric root from posterior adhesions, identifying the mesenteric artery below the pancreas, and free-dissecting this artery on the tumor capsule in the mobilized mesentery. Dissection was successful even with tumors initially judged inoperable unless tumor growth completely surrounded the mesenteric vessels or extended retroperitoneally. One patient was subjected to distal intestinal artery bypass. Symptom relief was been substantial and often of long duration after mesenteric tumor removal in patients who prior to surgery often had threatening intestinal ischemia. Patients with advanced midgut carcinoids may benefit markedly from dissectional removal of mesenteric tumors, which (conceivably better than conventional wedge resection) preserves the length of the remaining intestine.

Angiography↗

Influence of segmental spinal cord perfusion on intrathecal oxygen tension during experimental thoracic aortic crossclamping.

PURPOSE: The purpose of this study was to evaluate the possibility of identifying alterations in blood supply to the spinal cord during thoracic aortic crossclamping. METHODS: In 17 pigs, a multiparameter PO(2), PCO(2,) and pH sensor was introduced into the intrathecal space for continuous monitoring of cerebrospinal fluid (CSF) oxygenation during aortic crossclamping. An epidural laser Doppler probe was used to measure spinal cord flux. After insertion of an aortic shunt from the left subclavian to the left iliac artery and interruption of the right subclavian and lumbar arteries (L2-L5), the thoracic aorta just distal to the left subclavian artery was clamped for 60 minutes. By placement of the distal aortic crossclamping below the level of L1 in group A (n = 9 animals), perfusion of only the abdominal visceral arteries was maintained. In group B (n = 8 animals), the distal aortic crossclamping was above the level of T12, and thus some spinal cord perfusion was maintained through the aortic shunt. RESULTS: The significant decrease in CSF PO(2) was observed within 3 minutes after the placement of the proximal aortic crossclamping and was normalized in all animals after establishment of the shunt flow. In group A, distal aortic crossclamping caused a decrease in CSF PO(2) with at least 50% of the preclamping values within 3 minutes. The mean CSF PO(2) of 2.99 +/- 0.70 kPa at 60 minutes of distal aortic crossclamping in group B was significantly higher than in group A (0.11 +/- 0.11 kPa; P <. 001). In group A, PCO(2) measurements showed no significant changes in 3 minutes after distal aortic crossclamping but revealed significantly higher values at 30 and 60 minutes compared with group B. Spinal cord flux values showed similar changes as CSF PO(2) during the whole experiment in both groups. CONCLUSION: In this experimental model of aortic crossclamping, continuous CSF oxygen tension monitoring allows rapid detection of alterations in spinal cord circulation.

Animals↗

A multivariate analysis of factors affecting patency of femoropopliteal and femorodistal bypass grafting.

BACKGROUND: The most important factors that determine the outcome after femoropopliteal and femorodistal arterial reconstruction are still controversial. This report analysis the factors that determine the early and late patency of distal arterial reconstruction. PATIENTS AND METHODS: A retrospective analysis of patency after femorodistal arterial reconstruction with a new method for evaluation of angiographic runoff was performed for 336 arterial reconstructions. The different pre-, per- and postoperative risk factors were analysed in a Cox proportional hazards model. RESULT: The patency was significantly better for vein grafts in comparison to composite grafts and prosthetic grafts. It was 74% for vein, 46% for composite and 43% for prosthetic reconstructions, respectively, at 12 months after arterial reconstruction. The cumulative life table patency rate in extremities with good, intermediate and poor runoff was 62, 30 and 10%, respectively at 36 months. The patency rates for extremities operated on for claudication was significantly better than for extremities operated on for critical ischaemia. The multivariate analysis of different factors in a Cox analysis revealed that only the status of distal runoff, the graft material and the site of the distal anastomosis independently and significantly influenced the patency rates. CONCLUSIONS: A new model for evaluation of distal runoff proved to predict the patency rate of femoropopliteal and femorodistal arterial reconstructions reasonably well in this retrospective analysis.

Aged↗

A prolonged spinal cord ischaemia model in pigs. Passive shunting offers stable central haemodynamics during aortic occlusion.

OBJECTIVES: to evaluate the effect of a modified aortic shunt on central haemodynamic variables during experimental thoracic aortic occlusion in a prolonged spinal cord ischaemia model. MATERIAL AND METHODS: central haemodynamic variables were evaluated during aortic cross-clamping. In the shunt group (n=11), after the placement of proximal and distal aortic clamps, distal aortic perfusion was restored through an aortoiliac shunt via the left subclavian artery. In the no-shunt group (n=11), spinal cord ischaemia was achieved with only proximal aortic cross-clamping. The clamping time was 60 minutes in the shunt group and 30 minutes in the no-shunt group. RESULTS: in the no-shunt group, all animals needed inotropic support, vasodilators and buffers during the experiment. None of these drugs were needed in the shunt group. In the no-shunt group, cross-clamping caused a significant increase in mean arterial pressure and heart rate compared to baseline values. These variables were stable in the shunt group during aortic occlusion. In the reperfusion period cardiac output, heart rate and arterial pCO(2)were significantly higher in the no-shunt than in the shunt group. CONCLUSION: the present experimental spinal cord ischaemia model, using double aortic cross-clamping with shunt, offers improved central haemodynamics. This enables the study of prolonged selective spinal cord ischaemia without interaction from vasoactive drugs or systemic reperfusion.

Animals↗

Relationship between intrathecal oxygen tension and ultrastructural changes in the spinal cord during experimental aortic clamping.

OBJECTIVES: To investigate spinal cord ultrastructure related to cerebrospinal fluid (CSF) oxygenation. DESIGN: experimental aortic occlusion model with intrathecal oxygen tension monitoring. MATERIALS AND METHODS: Two groups of pigs underwent proximal (P) or double (D) aortic occlusion for 30 min followed by 1 h of reperfusion. In a third group (I) segmental arteries distal to T3 were clamped for 90 min. A thin pO(2), pCO(2) and pH sensor was placed intrathecally for continuous monitoring of CSF. Spinal cord segments were studied by electron microscopy (EM). RESULTS: In group P, CSF-pO(2)rapidly decreased during clamping and major changes in pH and pCO(2)were seen. EM demonstrated neuronal degeneration with loss of cellular integrity and severe affection of organelles. In the group D, CSF oxygenation decreased to about half, but with only moderate changes in the metabolic parameters. Group I showed no significant changes in CSF measurements. The latter groups were similar at EM, showing only mild mitochondrial changes. CONCLUSIONS: The level of CSF oxygenation during aortic cross-clamping or segmental artery interruption seems to correlate with ultrastructural changes in the spinal cord. This online intrathecal monitoring technique may provide valuable information on spinal cord circulation during thoracoabdominal aortic surgery.

Animals↗

Prevention of intimal hyperplasia by single-dose pre-insertion external radiation in canine-vein interposition grafts.

OBJECTIVES: to evaluate the efficacy of single-dose pre-insertion gamma radiation of vein grafts in the prevention of intimal hyperplasia. METHODS: femoral artery interposition grafts with internal jugular vein were inserted in 12 mongrel dogs. The animals were randomly divided into two groups. Immediately before graft replacement, jugular veins were treated with a single dose of cobalt-60 radiation at 14 Gy or received no radiation (control group). Six weeks after graft insertion, the vein grafts were pressure-perfusion fixed and harvested for the histomorphometric analysis. Quantitative data on anastomotic stenosis were calculated from Gilman parameters after cross-sectional image analysis. RESULTS: vein grafts treated with radiation demonstrated significantly decreased neointima formation compared with grafts in the control group. The mean Gilman parameter for the control group was 1.09 S.E.M. 0.34 mm and for the radiotherapy group was 0.65 S.E. M. 0.23 mm (p<0.05). All vein grafts in the radiotherapy group had a decreased amount of intimal and cellular infiltration. CONCLUSION: single-dose external pre-insertion gamma radiation of vein grafts reduced the amount of intimal hyperplasia in this animal model.

Animals↗

Gadolinium-enhanced magnetic resonance angiography, digital subtraction angiography and duplex of the iliac arteries compared with intra-arterial pressure gradient measurements.

PURPOSE: to compare gadolinium-enhanced magnetic resonance angiography (Gd-MRA), digital subtraction angiography (DSA) and duplex of the iliac arteries with intra-arterial pressure gradient measurement as the reference method. MATERIALS AND METHODS: Gd-MRA, DSA and duplex examinations of the iliac arteries were performed in 30 patients (60 arteries) with lower-limb arterial occlusive disease. In 29 arteries, pressure measurements were made (n=25) or the artery was found to be occluded on catheterisation (n=4). An aortofemoral peak systolic pressure gradient of 20 mmHg or more was regarded as haemodynamically significant. Stenoses with a diameter reduction of 50% or more on MRA or DSA, or an increase in peak systolic velocity greater than 150% (duplex) were considered significant. MRA examinations were evaluated by means of maximum intensity projections (MRA-MIP) and using source images and curved multiplanar reconstruction (MRA-MPR). RESULTS: the sensitivity (specificity) for a significant iliac artery stenosis were 81% (75%) for MRA-MIP, 76% (75%) for MRA-MPR, 86% (88%) for DSA, and 72% (88%) for duplex. CONCLUSION: with intra-arterial pressure measurements as the reference method, similar results were achieved with Gd-MRA, DSA and duplex concerning the detection of haemodynamically significant iliac artery stenoses. The use of source images and multiplanar reconstructions resulted in higher accuracy for the detection of occlusions.

Aged↗

Haemostasis in patients with Behçet's disease.

AIM: to determine whether Behçet's disease affects haemostatic function. SETTING: University Hospital, Turkey. PATIENTS: one hundred and twenty-seven consecutive patients with Behçet's disease, 34 of whom with a history of vascular involvement. METHODS: prothrombin fragment 1+2 tissue plasminogen activator, protein S and C, antithrombin, fibrinogen, von Willebrand factor, thrombomodulin and prothrombin time (PT) were measured in patient plasma. RESULTS: soluble thrombomodulin was significantly lower and von Willebrand factor (vWF) and tissue plasminogen activator (tPA) significantly higher in Behçet's patients. Patients with vascular involvement showed the highest levels of vWF and tPA. There was no activation of coagulation, not even in patients with an active disease at the time of sampling. CONCLUSION: there were indirect signs of endothelial activity or damage, particularly in patients with vascular involvement. Coagulation was not activated.

Adult↗

A new method of intrathecal PO2, PCO2, and pH measurements for continuous monitoring of spinal cord ischemia during thoracic aortic clamping in pigs.

BACKGROUND: Impaired spinal cord circulation during thoracic aortic clamping may result in paraplegia. Reliable and fast responding methods for intraoperative monitoring are needed to facilitate the evaluation of protective measures and efficiency of revascularization. METHODS: In 11 pigs, a multiparameter PO2, PCO2, and pH sensor (Paratrend 7, Biomedical Sensors Ltd, United Kingdom) was introduced into the intrathecal space for continuous monitoring of cerebrospinal fluid (CSF) oxygenation during thoracic aortic cross-clamping (AXC) distal to the left subclavian artery. A laser-Doppler probe was inserted into the epidural space for simultaneous measurements of spinal cord flux. Registrations were made before and 30 minutes after clamping and 30 and 60 minutes after declamping. The same measuring points were used for systemic hemodynamic and metabolic data acquisition. RESULTS: The mean CSF PO2 readings of 41 mm Hg (5.5 kPa) at baseline decreased within 3 minutes to 5 mm Hg (0.7 kPa) during AXC (P < .01). Spinal cord flux measurement responded immediately in the same way to AXC. Both methods indicated normalization of circulation during declamping. Significant (P < .01) changes were also observed in the CSF metabolic parameters PCO2 and pH. CONCLUSIONS: In this experimental model of spinal ischemia by AXC, online monitoring of intrathecal PO2, PCO2, and pH showed significant changes and correlated well with epidural laser-Doppler flowmetry (P < .01).

Animals↗

Anastomotic rupture at the site of polytetrafluoroethylene (PTFE) and distal vein cuff of femoropopliteal bypass. Two case reports.

Two female patients, 63 and 78 years of age, underwent femoropopliteal bypass with polytetrafluoroethylene (PTFE) graft and distal vein cuff. They developed graft occlusion due to false aneurysm at the site of vein cuff during one and eight weeks after surgery, respectively. Improper suture technique or weak vein wall might lead to suture disruption leading to false aneurysm as presented in this article.

Aged↗

[Clinical assessment of critical ischemia is always to be done prior to amputation].

Patients with critical limb ischemia (rest pain and/or ulcer/gangrene, together with low ankle pressure) are at risk of amputation, and should therefore undergo arterial reconstruction if that is at all technically possible. Thorough clinical investigation will usually distinguish patients in need of further evaluation by a vascular surgeon. No amputation should be undertaken without such evaluation. Diabetic patients belong to a special category, in that neuropathy makes it difficult to evaluate pain, and ankle pressure is often falsely high due to medial arterios sclerosis.

Amputation, Surgical↗

Surgical repair of type B aortic dissection complicated by early postoperative lung vein and artery thrombosis.

A 24-year old man with Marfan syndrome previously operated for abdominal aortic aneurysm and type A dissection sustained a type B dissection. He underwent graft replacement of the descending and upper abdominal aorta, complicated by infarction of the left upper lobe and lobectomy was carried out. The postoperative course was uneventful. The mechanism for this rare complication is discussed.

Adult↗