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Biomedical subjects

S Thelin

Publications and source records attributed to S Thelin.

At least 19 recordsLinked to original sources
PubMed2006

Remodeling of the thoracic aorta after stent grafting of type B dissection: a Swedish multicenter study.

AIM: Endovascular repair of complicated type B dissections has evolved as a promising alternative to open repair. Previous studies have indicated that continued false lumen flow is a predictor of continued aortic dilatation and risk of rupture during follow-up. This multicenter study was conducted to analyze the postoperative changes of the false lumen after endografting of complicated type B dissections. METHODS: All patients treated with endovascular stent grafts for thoracic type B dissections at 5 major Vascular Centers in Sweden were identified through local databases. Review of charts and all available pre- and postoperative CT scans were performed to identify demographics, indications for repair as well as postoperative changes of the aorta and false lumen. RESULTS: A total of 129 patients treated for type B dissections between 1994 and December 2005 were identified. Median radiological follow-up was 14 months. Fourteen patients died perioperatively leaving 115 patients available for analysis. Seventy-four of these had CT imaging of sufficient quality for morphological analysis. The vast majority of acute patients were treated for rupture or end-organ ischemia whereas most chronic patients were treated for asymptomatic aneurysms. In 80% of patients, the false lumen thrombosed along the stent graft but it remained perfused distal to the stent graft fixation in 50% of patients. Only 5% of patients presented with aortic enlargement of the stent grafted area when adequate proximal sealing was achieved. The distal, uncovered aorta displayed expansion in 16% of patients. CONCLUSIONS: The stent grafted thoracic aorta after type B dissection appears to be stabilized by covering the primary entry site with a stent graft in the majority of both acute and chronic dissections. The uncovered portion of the aorta distal to the stent graft, however, remains at risk of continuous dilatation. Stent grafting for complicated type B thoracic dissections seems to be a treatment option with reasonable morbidity and mortality even though the incidence of severe complications is still significant.

Adult↗
PubMed2002

Cell adhesion and tissue factor upregulation in oxygenators used during coronary artery bypass grafting are modified by the Corline Heparin Surface.

OBJECTIVE: Cardiopulmonary bypass (CPB) is associated with inflammatory response and activation of coagulation. We investigated the influence of a new heparin surface on the activation of cells retrieved from oxygenators used during coronary artery bypass grafting (CABG). DESIGN: Sixty patients undergoing CABG with CPB were randomly assigned to either uncoated or completely Corline Heparin Surface (CHS)-coated circuits with one of three different levels of systemic heparin: standard, high or low. At end of surgery adhered cells were retrieved from the oxygenators and cell count, tissue factor (TF)- and CD11b-expression on monocytes and monocytic TFmRNA were analysed. RESULTS: The heparin coating of the oxygenator prevented adhesion of granulocytes, monocytes and platelets. TF-expression on monocytes from the oxygenators was significantly higher than on circulating cells in all groups. Monocytes from the uncoated oxygenators showed low levels of TF-expression with high levels of TFmRNA. The coated group with high level of heparin showed higher surface-expression of TF with low levels of TFmRNA. CONCLUSION: The CHS was most biocompatible with the standard level of heparin used during CABG whereas elevation of systemic heparin rather increased the activation and TF upregulation in monocytes from oxygenators.

Aged↗
PubMed2001

Nucleoside transport inhibition in ischemic myocardium results in enhanced taurine efflux.

We measured with the microdialysis technique energy-related metabolites in ischemic myocardium over time in an experimental pig model. Emphasis was put on the dipyridamole effect when administered in the microdialysis probe inserted in ischemic myocardium. Not only adenosine but also taurine and pyruvate concentrations were significantly higher in the microdialysate during the periods of ischemia and extracorporeal circulation with cardioplegia. The enhanced efflux of taurine in ischemic myocardium induced by dipyridamole is a new finding. A mechanistic role of taurine in the prevention of Ca(2+) overload in ischemic myocytes is discussed. Also, taurine may have stimulatory effects on glycolysis in ischemic heart.

Adenosine↗
PubMed2001

The incidence of chronic post-sternotomy pain after cardiac surgery--a prospective study.

BACKGROUND: Post-sternotomy pain is sometimes a sequela of cardiac surgery. The incidence, characteristics and clinical course of post-sternotomy pain are not well known. The aim of our study was to determine the incidence of chronic post-sternotomy pain in patients undergoing sternotomy for cardiac surgery in general and according to the specific surgical procedure. METHOD: In a prospective manner, a group of 349 consecutive patients were evaluated for chronic post-sternotomy pain one year after surgery. The patients were asked in a postal questionnaire to describe and score any persistent pain following the surgical procedure. The patients were classified into 3 sub-groups according to surgical procedure. The first group consisted of patients operated for coronary artery by-pass grafting (CABG) including internal thoracic artery grafting (ITAG). The second group included patients operated with CABG without ITAG and the third group of patients with valve replacement without CABG. RESULT: A total of 318 patients (91%) answered the questionnaire of whom 90 (28%) reported chest discomfort different from what they experienced before surgery. The scoring on the visual analogue scale (VAS, 0-100 mm) showed that 41 patients (13%) reported maximum pain intensity > or =30 mm (moderate pain), and 14 of these patients (4%) scored > or =54 mm (severe pain). There was no statistically significant difference in pain incidence and pain intensity when comparing the patients subjected to different surgical procedures. CONCLUSIONS: This prospective study shows that the overall incidence of non-cardiac pain after sternotomy for cardiac surgery is high (28%). Most patients experience a modest pain intensity but some (1%) report severe pain, never being lower than 54 mm on VAS. The study also indicates that the incidence of pain after sternotomy is not only associated with harvest of the ITA and additional aetiological factors must be sought.

Adult↗
PubMed2001

Energy-related metabolites during and after induced myocardial infarction with special emphasis on the reperfusion injury after extracorporeal circulation.

In the clinical setting great efforts have been made with contradictory results to operate upon acutely myocardial ischaemic patients. The reasons for the absence of clear-cut results are not well understood nor are they scientifically explored. To resolve this problem further, we attempted to design an experimental in vivo model to mimic acute myocardial ischaemia followed by extracorporeal circulation (ECC) and reperfusion. One of the main targets of our protocol was monitoring of myocardial energy metabolism by microdialysis (MCD) during the periods of coronary occlusion (60 min), hypothermic (30 degrees C) ECC and cardioplegia (45 min), followed by reperfusion with (30 min) and without (60 min) ECC. In eight anaesthetized, open-chest pigs, myocardial lactate, pyruvate, adenosine, taurine, inosine, hypoxanthine and guanosine were sampled with MCD in both ischaemic and non-ischaemic areas. Myocardial area at risk and infarct size were quantified with the modified topographical evaluation methods. The principal finding with this experimental setup was a biphasic release pattern of lactate, adenosine, taurine, inosine, hypoxanthine and guanosine from ischaemic myocardium. Lactate levels were equally high in reperfused ischaemic and non-ischaemic myocardial tissue. Pyruvate demonstrated consistently higher values in non-ischaemic myocardium throughout the experiment. A pattern was discernible, lactate being a marker of compromised cell energy metabolism, and taurine being a marker of disturbed cell integrity. Of special interest was the increased level of pyruvate in microdialysates of non-ischaemic myocardium as compared with its ischaemic counterpart. In conclusion, we found disturbances in energy metabolism and cell integrity not only in ischaemic but also in non-ischaemic tissue during reperfusion implying that non-ischaemic myocardium demonstrated an unexpected accumulation of lactate and pyruvate. These new findings could at least partly be explicatory to the increased risk of heart surgery in connection with acute myocardial infarction.

Adenosine↗
PubMed2001

Discrepant outcome between myocardial energy-related metabolites and infarct size limitation during retroperfusion of the coronary sinus.

The basic idea of retroperfusion of the coronary sinus (RCS) is to ameliorate detrimental consequences of myocardial ischaemia. Several experimental models of RCS have been introduced, most with an emphasis on functional myocardial status. Since only few studies have been devoted to energy metabolic considerations and none to continuous monitoring of energy-related metabolites of myocardium during RCS, we here present such a study using microdialysis. This study comprised the following components: Coronary occlusion and drainage on the beating heart with RCS-assist (60 min), hypothermic (30 degrees C) extracorporeal circulation (ECC) and cardioplegia (45 min), reperfusion and rewarming to 38 degrees C on ECC (30 min). The microdialysis analytical outcome mainly reflected anaerobic energy metabolism in potentially ischaemic myocardium. Additionally, a pronounced increase of microdialysate content of lactate, pyruvate and guanosine was observed in non-ischaemic myocardium especially during the reperfusion phase. The planimetric calculation revealed an infarct size reduction from 69% to 19% and was not correlated to clear-cut improvements of potentially ischaemic myocardial energy metabolism. We conclude that prolonged (60 min) anaerobic energy metabolism does not pose an immediate threat to cell viability but could even sustain myocyte survival.

Animals↗
PubMed2001

Influence of low proximal aortic pressure on spinal cord oxygenation in experimental thoracic aortic occlusion.

BACKGROUND: To evaluate the effect of low proximal aortic pressure on cerebrospinal fluid (CSF) oxygenation in an experimental thoracic occlusion model. METHODS: In nine pigs, continuous intrathecal pO(2), pCO(2) and pH monitoring was used during double descending thoracic aortic clamping following insertion of an aorto-aortic shunt. In five pigs, the shunt was connected to a citrated bag adjusted at approximately 40-45 cm above the heart for partial exsanguination in order to decrease mean proximal aortic pressure (MPAP) to below 50 mmHg. In four animals, sodium nitroprusside infusion was used for this purpose. RESULTS: Intrathecal pO(2) demonstrated a significant decrease from 4.9+/-2.1 to 2.9+/-2.4 kPa after 10 minutes of aortic cross-clamping. Lowering proximal aortic pressure caused a further significant decrease to 1.2+/-1.7 kPa (p<0.05). In seven pigs (5 in the exsanguination and 2 in the vasodilator group), restoration of mean proximal aortic pressure to 94.0+/-27.7 caused a recovery of CSF pO(2) from 1.2+/-1.9 to 2.8+/-3.0 (p<0.05). CONCLUSIONS: The results of this study demonstrate that MPAP which provides spinal cord perfusion through subclavian-vertebral arteries are crucial for maintenance of spinal cord oxygenation during thoracic aortic occlusion in this pig model.

Animals↗
PubMed2000

No benefit of reduced heparinization in thoracic aortic operation with heparin-coated bypass circuits.

BACKGROUND: Heparin coating of the cardiopulmonary bypass circuit attenuates inflammatory response and confer clinical benefits in cardiac operations. The positive effects may be amplified with reduced systemic heparin dosage. We studied markers of inflammation and coagulation in thoracic aortic operations with heparin-coated circuits and standard vs reduced systemic heparinization. METHODS: Thirty patients were randomized to standard (group S; 300 IU/kg initially; activated clotting times [ACT] > 480 seconds; 5,000 IU in prime; n = 16) or reduced (group R; 100 IU/kg initially; ACT > 250 seconds; 2,500 IU in prime; n = 14) dose systemic heparin. The following markers were analyzed perioperatively: (a) inflammatory response; acute phase cytokine interleukin-6, and granulocytic proteins myeloperoxidase and lactoferrin; (b) complement activation; factor C3a and the C5a-9 terminal complement complex [TCC]; and (c) coagulation; thrombin-antithrombin III complex. RESULTS: The clinical outcome did not differ between groups. Four (29%) patients in group R had a perioperative thromboembolic event. All studied markers were significantly elevated during and throughout cardiopulmonary bypass in both groups. Maximal values were higher in group R for all variables except for TCC. There were no statistically significant intergroup differences regarding markers of inflammation, complement activation, or coagulation activation. CONCLUSIONS: The blood trauma in thoracic aortic operation is extensive, as reflected by the elevation of the studied biochemical markers, even when heparin-coated cardiopulmonary bypass circuits are used. In this study, we did not detect any benefits, either biochemical or clinical, of reducing the dose of systemic heparin.

Aged↗
PubMed2000

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↗
PubMed2000

Heparin-coated cardiopulmonary bypass circuits reduce circulating complement factors and interleukin-6 in paediatric heart surgery.

Children are sensitive to the inflammatory side effects of cardiopulmonary bypass (CPB). Our intention was to investigate if the biocompatibility benefits of heparin-coated CPB circuits apply to children. In 20 operations, 19 children were randomized to heparin-coated (group HC, n = 10) or standard (group C, n = 10) bypass circuits. Plasma levels of acute phase reactants, interleukins, granulocytic proteins and complement factors were measured. All were significantly elevated after CPB. Levels of complement factor C3a (851 (791-959)ng/ml [median with quartiles] in group C, 497 (476-573)ng/ml in group HC, p < 0.001), Terminal Complement Complex (114 (71-130) AU/ml in group C, 35.5 (28.9-51.4) AU/ml in group HC, p < 0.001), and interleukin-6 (570 (203-743) pg/ml in group C, 168 (111-206)pg/ml in group HC, p = 0.005), were significantly reduced in group HC. Heparin-coated CPB circuits improve the biocompatibility of CPB during heart surgery in the paediatric patient population, as reflected by significantly reduced levels of circulating complement factors and interleukin-6.

Anticoagulants↗
PubMed1999

Quality of life in survivors of thoracic aortic surgery.

BACKGROUND: The results of surgical repair of thoracic aortic lesions are improving. Still, mortality and morbidity are considerable. Outcomes need to be studied in greater detail. We studied quality of life in survivors of thoracic aortic surgery, which has not been reported before. METHODS: During a 5-year period, 115 patients underwent thoracic aortic repair. All mid- to long-term survivors (n = 81; median follow-up time, 26 months) received the Short Form-36 (SF-36) health questionnaire plus specific questions related to surgery. Five patients were lost to follow-up. RESULTS: Scores for the eight dimensions of SF-36 (range, 0 to 100, 100 reflecting best function) were compared with a normal population. The mean deficits from the norm were bodily pain, 0.1 (95% confidence interval, -3.4 to 3.6) points below norm; mental health, 8.3 (5.7 to 10.9); vitality, 9.5 (6.7 to 12.3); social functioning, 10.1 (6.9 to 13.3); general health, 11.1 (8.5 to 13.7); physical functioning, 16.6 (13.4 to 19.8); role emotional, 20.6 (15.3 to 25.9); and role physical, 30.2 (24.7 to 35.7). Subgroup scores for acute versus elective cases, ascendens versus arch versus descendens procedures, and major complication versus no major complication were not significantly different. Sixty-six percent (50 of 76) stated a general health perception improvement. In 82% (62 of 76), the quality of life improved or was preserved. Ninety-one percent (69 of 76) considered the operation successful. CONCLUSIONS: Considering the seriousness of the conditions, quality-of-life scores after thoracic aortic surgery were acceptable, although lower than in a normal population, except for bodily pain. Postoperative quality of life justifies thoracic aortic surgical repair.

Aortic Dissection↗
PubMed1999

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↗
PubMed1998

Use of a vital capacity maneuver to prevent atelectasis after cardiopulmonary bypass: an experimental study.

BACKGROUND: Respiratory failure secondary to cardiopulmonary bypass (CPB) remains a major complication after cardiac surgery. The authors previously found that the increase in intrapulmonary shunt was well correlated with the amount of atelectasis. They tested the hypothesis that post-CPB atelectasis can be prevented by a vital capacity maneuver (VCM) performed before termination of the bypass. METHODS: Eighteen pigs received standard hypothermic CPB (no ventilation during bypass). The VCM was performed in two groups and consisted of inflating the lungs during 15 s to 40 cmH2O at the end of the bypass. In one group, the inspired oxygen fraction (FIO2) was then increased to 1.0. In the second group, the FIO2 was left at 0.4. In the third group, no VCM was performed (control group). Ventilation-perfusion distribution was measured with the inert gas technique and atelectasis by computed tomographic scanning. RESULTS: Intrapulmonary shunt increased after bypass in the control group (from 4.9 +/- 4% to 20.8 +/- 11.7%; P < 0.05) and was also increased in the vital capacity group ventilated with 100% oxygen (from 2.2 +/- 1.3% to 6.9 +/- 2.9%; P < 0.01) but was unaffected in the vital capacity group ventilated with 40% oxygen. The control pigs showed extensive atelectasis (21.3 +/- 15.8% of total lung area), which was significantly larger (P < 0.01) than the proportion of atelectasis found in the two vital capacity groups (5.7 +/- 5.7% for the vital capacity group ventilated with 100% oxygen and 2.3 +/- 2.1% for the vital capacity group ventilated with 40% oxygen. CONCLUSION: In this pig model, postcardiopulmonary bypass atelectasis was effectively prevented by a VCM.

Animals↗
PubMed1997

The macrophage migration inhibitory factor MIF is a phenylpyruvate tautomerase.

A macrophage migration inhibitory factor (MIF), originally described as a product of activated lymphocytes, has been defined as a 12 kDa protein, expressed in a wide variety of tissues. Here MIF is identified as a phenylpyruvate tautomerase (EC 5.3.2.1) having p-hydroxyphenylpyruvate and phenylpyruvate as its natural substrates. The definition of MIF as an enzyme may yield insight into the mechanism of action of this proinflammatory and immunomodulating cytokine.

Amino Acids↗