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Biomedical subjects

Akif Undar

Publications and source records attributed to Akif Undar.

18 recordsLinked to original sources
PubMed2003

Use of near-infrared spectroscopy to monitor regional cerebral oxygen saturation during infrarenal aortic crossclamping in piglets.

PURPOSE: The hemodynamic changes induced by infrarenal aortic crossclamping have been well documented, but the effects of such crossclamping on cerebral perfusion are unknown. To investigate these effects, we used near-infrared spectroscopy (NIRS) to monitor regional cerebral oxygen saturation (rSO2) during infrarenal aortic crossclamping in a piglet model. METHODS: The study involved 19 piglets, each weighing 7.8 +/- 1 kg. The NIRS sensor was placed on each animal's forehead. General anesthesia was induced, and the infrarenal abdominal aorta was mobilized through a laparotomy. After heparin (1 mg/kg) was administered, crossclamps were applied proximally and distally. A 2 mm segment was resected from the proximal aortic stump, and an aorto-aortic anastomosis was performed. RESULTS: Crossclamping lasted for 30.6 +/- 6.7 min. Between the time of baseline measurement and clamp application, the rSO2 did not decrease significantly (65.4%+/- 8.9% vs. 62.4%+/- 7.8%). However, significant decreases in the rSO2 occurred between baseline measurement and clamp removal (65.4%+/- 8.9% vs. 55.7%+/- 8.9%; P<0.01), between baseline measurement and the end of surgery (65.4%+/- 8.9% vs. 57.7%+/- 7.5%; P<0.01), and between clamp application and removal (62.4%+/- 7.8% vs. 55.7%+/- 8.9%; P<0.01). At these same intervals, no intergroup differences occurred in the temperature, heart rate, or mean arterial pressure. CONCLUSION: Infrarenal aortic crossclamping significantly decreases the rSO2. NIRS, which has the advantages of being non-invasive and continuous, may be useful for monitoring this variable intraoperatively.

Analysis of Variance↗
PubMed2003

First Turkish experience with the MicroMed DeBakey VAD.

Mechanical bridging to cardiac transplantation with a ventricular assist device may be a life-saving procedure for patients with end-stage heart failure. Here we report our 3 cases of patients implanted with the MicroMed DeBakey VAD (ventricular assist device). Three male patients, aged 37, 41, and 40, had end-stage left heart failure due to idiopathic cardiomyopathy and were listed for cardiac transplantation. They had progressive hemodynamic deterioration. Although Patient 1 underwent surgery, after device implantation, for bowel necrosis caused by thromboemboli of unknown origin, heart transplantation was performed 70 days after implantation. Pump thrombosis occurred in Patient 2 on the 120th day. Outflow graft ligation was performed because the patient refused a pump exchange. This patient died on the 25th day after ligation and the 145th day after ventricular assist device implantation. A heparin-coated version of the device was implanted in Patient 3, whose preoperative profound biventricular failure had been improved by inotropic medication and intra-aortic balloon pump support. Successful heart transplantation was performed 161 days after implantation. These are the 1st implantations of a left ventricular assist device in Turkey. From these cases, we have learned that the DeBakey VAD supplies adequate blood flow during the bridging period and, due to its simplicity, portability, and low infection rate, enables discharge of the patient from the hospital. However, preoperative psychological evaluation and postoperative psychological support are important for a successful bridging procedure, as is close observation of coagulation and of pump operation.

Adult↗
PubMed2002

BioGlue surgical adhesive impairs aortic growth and causes anastomotic strictures.

BACKGROUND: BioGlue surgical adhesive (CryoLife, Inc, Kennesaw, GA) is currently being used to secure hemostasis at cardiovascular anastomoses in adults. Interference with vessel growth would preclude its use during congenital heart surgery. The purpose of this study was to determine if BioGlue reinforcement of aortic anastomoses impairs vessel growth and causes strictures. METHODS: Ten 4-week-old piglets (8.0 +/- 1.4 kg) underwent primary aorto-aortic anastomoses. Five piglets were randomly assigned to anastomotic reinforcement with BioGlue. After a 7-week growth period, the aortas were excised for morphometric analysis and histopathology. RESULTS: Weight gains were similar in both groups. In BioGlue animals, however, aortic circumference increased only 1.5 +/- 0.8 mm (versus 2.7 +/- 0.8 mm in controls; p = 0.054). BioGlue animals developed a 33.9% stenosis of the aortic lumen area (versus 3.7% in controls, p = 0.038). Adventitial changes reflecting tissue injury and fibrosis were present in all BioGlue animals versus none of the control animals (p = 0.008). CONCLUSIONS: BioGlue reinforcement impairs vascular growth and causes stricture when applied circumferentially around an aorto-aortic anastomosis. This adhesive should not be used on cardiovascular anastomoses in pediatric patients.

Age Factors↗
PubMed2002

Novel anti-factor D monoclonal antibody inhibits complement and leukocyte activation in a baboon model of cardiopulmonary bypass.

BACKGROUND: Adverse outcomes after cardiopulmonary bypass (CPB) are often related to systemic inflammation triggered by complement and leukocyte activation. To determine how inhibition of the alternative complement pathway affects systemic inflammation and tissue injury, we studied a novel monoclonal antibody (Mab), anti-human factor D murine Mab 166-32, in baboons. METHODS: Fourteen baboons (mean weight, 15 kg) underwent hypothermic CPB. The treatment group (n = 7) received a single injection of anti-factor D Mab 166-32 (5 mg/kg), and the control group (n = 7) was given saline solution. After initiation of CPB, all animals were subjected to 20 minutes of core cooling (rectal temperature, 27 degrees C), followed by 60 minutes of aortic cross-clamping, 25 minutes of rewarming, and 30 minutes of normothermic CPB. Blood samples were collected before CPB, during CPB, and 1, 2, 3, 6, and 18 hours after CPB. To measure neutrophil and monocyte activation, we performed flow cytometry for CD11b expression, ELISA for complement activation (Bb, C3a, C4d, and sC5b-9) and interleukin-6 (IL-6) production, and tissue injury studies for creatine kinase MB isoenzymes (CK-MB), creatine kinase (CK), and lactic dehydrogenase (LDH) levels. RESULTS: Anti-factor D Mab almost completely inhibited plasma Bb, C3a, and sC5b-9 production during CPB (P < .001). CD11b expression on neutrophils (129 +/- 5% vs. 210 +/- 42%; P = .0006) and on monocytes (139 +/- 14% vs. 245 +/- 43%; P = .0002) was also lower in the treatment group during CPB. The treated animals had a significantly smaller increase in plasma IL-6 concentrations than did the control animals (71 +/- 27 pg/mL vs. 104 +/- 54 pg/mL; P = .0002). CK-MB levels were also lower in the treatment group 6 hours after the end of CPB (204 +/- 30 vs. 335 +/- 59 IU/L; P = .003) and 18 hours after the end of CPB (P < .05). Creatine kinase levels (6 and 18 hours after the end of CPB) and LDH levels (3 and 6 hours after the end of CPB) showed patterns similar to those of CK-MB (P < .05). CONCLUSIONS: The alternative complement pathway plays a major role in systemic inflammation during CPB. Inhibition of complement activation via the alternative pathway by anti-factor D Mab 166-32 significantly reduces leukocyte activation and tissue injury in our baboon model.

Animals↗
PubMed2002

Anomalous origin of left coronary artery from the right pulmonary artery in association with type III aortopulmonary window and interrupted aortic arch.

Anomalous origin of the left coronary artery from the pulmonary artery, also known as Garland-Bland-White syndrome, usually occurs as an isolated condition. We report an infant with caudal regression sequence diagnosed with interrupted aortic arch type B and type III aortopulmonary window, who was found to have anomalous origin of the left coronary artery from the right pulmonary artery at surgical repair. Successful repair of the aortopulmonary window and interruption was performed with reimplantation of the left coronary artery into the ascending aorta. This report highlights the importance of closely assessing the coronary ostia in patients undergoing complex aortopulmonary window repair.

Anastomosis, Surgical↗
PubMed2002

Pediatric physiologic pulsatile pump enhances cerebral and renal blood flow during and after cardiopulmonary bypass.

Controversy over benefits of pulsatile flow after pediatric cardiopulmonary bypass (CPB) continues. Our study objectives were to first, quantify pressure and flow waveforms in terms of hemodynamic energy, using the energy equivalent (EEP) formula, for direct comparisons, and second, investigate effects of pulsatile versus nonpulsatile flow on cerebral and renal blood flow, and cerebral vascular resistance during and after CPB with deep hypothermic circulatory arrest (DHCA) in a neonatal piglet model. Fourteen piglets underwent perfusion with either an hydraulically driven dual-chamber physiologic pulsatile pump (P, n = 7) or a conventional nonpulsatile roller pump (NP, n = 7). The radiolabeled microsphere technique was used to determine the cerebral and renal blood flow. P produced higher hemodynamic energy (from mean arterial pressure to EEP) compared to NP during normothermic CPB (13 +/- 3% versus 1 +/- 1%, p < 0.0001), hypothermic CPB (15 +/- 4% versus 1 +/- 1%, p < 0.0001) and after rewarming (16 +/- 5% versus 1 +/- 1%, p < 0.0001). Global cerebral blood flow was higher for P compared to NP during CPB (104 +/- 12 ml/100g/min versus 70 +/- 8 ml/100g/min, p < 0.05). In the right and left hemispheres, cerebellum, basal ganglia, and brainstem, blood flow resembled the global cerebral blood flow. Cerebral vascular resistance was lower (p < 0.007) and renal blood flow was improved fourfold (p < 0.05) for P versus NP, after CPB. Pulsatile flow generates higher hemodynamic energy, enhancing cerebral and renal blood flow during and after CPB with DHCA in this model.

Age Factors↗
PubMed2002

Effects of mild hypothermic cardiopulmonary bypass on blood viscoelasticity in coronary artery bypass grafting patients.

The purpose of this study was to determine the changes in blood viscoelasticity during and after coronary artery bypass grafting (CABG) and to identify correlations between blood viscoelasticity and patients' age, duration of cardiopulmonary bypass (CPB), and cross-clamp time. After Institutional Review Board approvals, patients (n = 10) who were subjected to mild hypothermic CPB were included in this study. Viscosity and elasticity were measured at strains of 0.2, 1, and 5 using a Vilastic-3 Viscoelasticity Analyzer. Arterial blood samples were collected pre-CPB, on normothermic CPB, hypothermic CPB, after rewarming, and after CPB. Viscosity and elasticity at strains of 0.2 and 1 were altered significantly during and after CPB compared to the pre-CPB (p < 0.01). In particular, elasticity of blood was diminished during normothermic bypass and could not be recovered after CPB (p < 0.01). Although there were strong correlations between blood viscoelasticity, duration of CPB, and cross-clamp time on normothermic CPB, only the patients' age showed a positive correlation between viscosity (r = 0.61, p = 0.05), and elasticity (r = 0.89, p < 0.001) after CPB. These results suggest that mild hypothermic CPB alters the blood viscoelasticity during and after CABG.

Age Factors↗
PubMed2002

Do S100beta protein level increases due to inflammation during cardiopulmonary bypass occur without any neurological deficit?

PURPOSE: S100beta protein level correlates with the duration of cardiopulmonary bypass (CPB) and aortic crossclamp times, but is different during pulsatile and nonpulsatile CPB. In this study, we investigated the time course of the release of S100beta protein during and after pulsatile and nonpulsatile CPB. PATIENTS AND METHODS: This is a prospective study. Twenty patients had open-heart surgery with pulsatile flow and 20 with nonpulsatile flow. We compared complement proteins, interleukins, white blood cells and S100beta protein before the initiation of CPB, immediately prior to aortic crossclamping, following unclamping, and at postoperative 1st and 24th hours. RESULTS: In the pulsatile CPB group following aortic unclamping, S100beta protein (p = 0.028) and C3a (p = 0.011) levels were significantly lower than those of the nonpulsatile group. In the pulsatile CPB group at postoperative first hour, C3a level (p = 0.018) and absolute neutrophil count (p = 0.034) were significantly lower than those of the nonpulsatile group. None of the patients developed a neurological deficit and all of the patients survived after the operation and were discharged from the hospital. CONCLUSION: During CPB, serum S100beta protein level increases and this increase is higher in the nonpulsatile group. High serum level of S100beta protein is associated with increased levels of serum inflammatory mediators and systemic inflammatory response.

Adult↗
PubMed2002

The ABCs of research on pulsatile versus nonpulsatile perfusion during cardiopulmonary bypass.

The literature suggests that pulsatile flow should be routinely used during cardiopulmonary bypass (CPB) in moderate- to high-risk cardiac surgery patients, especially those who must undergo more than 45 minutes of aortic crossclamping. Nevertheless, the use of pulsatile versus nonpulsatile perfusion remains controversial, mainly owing to a lack of precise, complete quantification of pressure-flow waveforms. This editorial briefly summarizes the major factors, or 'basic ABCs, ' that affect the validity of research in this area. A. Because pulsatile flow depends on an energy gradient, investigators must quantify the difference in the hemodynamic energy levels produced by specific pulsatile and nonpulsatile pumps before meaningful direct comparison of these two perfusion modes can be possible. B. The energy equivalent pressure (EEP) formula should be used for this purpose. C. In conducting clinical trials of the perfusion modes, researchers must use appropriate patient-selection criteria, use pulsatile flow continuously during CPB, and choose extracorporeal-circuit components carefully. By following these basic ABCs, researchers will produce more valid and meaningful results that will translate into better outcomes for CPB patients.

Cardiac Surgical Procedures↗
PubMedDate not supplied

Pulsatile perfusion improves regional myocardial blood flow during and after hypothermic cardiopulmonary bypass in a neonatal piglet model.

Pediatric myocardial related morbidity and mortality after cardiopulmonary bypass (CPB) are well documented, but the effects of pulsatile perfusion (PP) versus nonpulsatile perfusion (NPP) on myocardial blood flow during and after hypothermic CPB are unclear. After investigating the effects of PP versus NPP on myocardial flow during and after hypothermic CPB, we quantified PP and NPP pressure and flow waveforms in terms of the energy equivalent pressure (EEP) for direct comparison. Ten piglets underwent PP (n = 5) or NPP (n = 5). After initiation of CPB, all animals underwent 15 minutes of core cooling (25 degrees C), 60 minutes of hypothermic CPB with aortic cross-clamping, 10 minutes of cold reperfusion, and 30 minutes of rewarming. During CPB, the mean arterial pressure (MAP) and pump flow rates were 40 mm Hg and 150 ml/kg per min, respectively. Regional flows were measured with radiolabeled microspheres. During normothermic CPB, left ventricular flow was higher in the PP than the NPP group (202+/-25 vs. 122+/-20 ml/l 00 g per min). During hypothermic CPB, no significant intragroup differences were observed. After 60 minutes of ischemia and after rewarming (276+/-48 vs. 140+/-12 ml/100 g per min; p < 0.05) and after CPB (271+/-10 vs. 130+/-14 ml/100 g per min; p < 0.05), left ventricular flow was higher in the PP group. Right ventricular flow resembled left ventricular flow. The pressure increase (from MAP to EEP) was 10+/-2% with PP and 1% with NPP (p < 0.0001). The increase in extracorporeal circuit pressure (ECCP) (from ECCP to EEP) was 33+/-10% with PP and 3% with NPP (p < 0.0001). Pulsatile flow generates significantly higher energy, enhancing myocardial flow during and after hypothermic CPB and after 60 minutes of ischemia in this model.

Animals↗