Absence Of Perfusion Research Articles

Tödliche Lungenembolie nach Lysetherapie bei posttraumatischer Nierenvenenthrombose

A 30-year-old man was hospitalized because of increasing dyspnoea for 4 weeks. Chest X-ray demonstrated an infiltrate in the right upper lobe and enlargement of the central pulmonary arteries. Lung perfusion scintigraphy revealed, typical of embolism, absent perfusion of the entire right upper lobe, as well as segmental embolism in the left upper and basal lobes. Phlebography of the legs and pelvis was unremarkable. Intravenous heparin treatment was begun (initially 1,250 IU/h, then dosage adjusted according to the partial thromboplastin time). Nonetheless the patient's condition deteriorated the next day and the respiratory failure increased (pO2 61 mm Hg despite oxygen supply). Streptokinase was then infused in ultra-high dosage, 9 million units over 6 hours. But the patient died of cardiocirculatory failure 4 hours after the streptokinase infusion had been finished. Autopsy revealed fulminant recurrent pulmonary embolism with occlusion of the right main pulmonary artery. The emboli had their origin in renal vein thrombosis extending into the inferior vena cava, which had probably been caused by slight trauma to the flank during a game of squash 6 weeks previously.

Significance of Absent Bowel Perfusion in Patients with Necrotizing Enterocolitis

HomeRadioGraphicsVol. 28, No. 1 PreviousNext Letter to the EditorSignificance of Absent Bowel Perfusion in Patients with Necrotizing EnterocolitisAkshay Kumar SaxenaAkshay Kumar SaxenaAuthor AffiliationsDepartment of Radio Diagnosis and Imaging, Post Graduate Institute of Medical Education and Research, Sector-12, Chandigarh 160012, India, e-mail: [email protected]Akshay Kumar SaxenaPublished Online:Jan 1 2008https://doi.org/10.1148/radiographics.28.1.0280319MoreSectionsFull textPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In References1 EpelmanM, Daneman A, Navarro OM, et al. Necrotizing enterocolitis: review of state-of-the-art imaging findings with pathologic correlation. RadioGraphics2007; 27: 285–305. Link, Google Scholar2 SilvaCT, Daneman A, Navarro OM, et al. Correlation of sonographic findings and outcome in necrotizing enterocolitis. Pediatr Radiol2007; 37: 274–282. Crossref, Medline, Google Scholar3 FaingoldR, Daneman A, Tomlinson G, et al. Necrotizing enterocolitis: assessment of bowel viability with color Doppler US. Radiology2005; 235: 587–594. Link, Google ScholarArticle HistoryPublished in print: Jan 2008 FiguresReferencesRelatedDetailsCited ByThe Journal of Maternal-Fetal & Neonatal Medicine, Vol. 24, No. 4Recommended Articles Contrast-enhanced US in Pediatric Patients: Overview of Bowel ApplicationsRadioGraphics2020Volume: 40Issue: 6pp. 1743-1762Extrapancreatic Advanced Endoscopic InterventionsRadioGraphics2022Volume: 42Issue: 2pp. 379-396Pediatric Liver Transplant: Techniques and ComplicationsRadioGraphics2017Volume: 37Issue: 6pp. 1612-1631CT of Penetrating Abdominopelvic TraumaRadioGraphics2021Volume: 41Issue: 4pp. 1064-1081Imaging Evaluation of Abdominopelvic Gunshot TraumaRadioGraphics2020Volume: 40Issue: 6pp. 1766-1788See More RSNA Education Exhibits Beyond Necrotizing Enterocolitis: Sonographic Findings on Uncommon Causes of Pneumatosis Intestinalis in the Neonatal and Pediatric Emergency ScenarioDigital Posters2020Contrast-Enhanced Ultrasound (CEUS) in Pediatric Patients: Overview of Bowel ApplicationsDigital Posters2019Practical Approach to Liver Transplant Complications in the Emergency Department - What a Radiologist Needs to Know!Digital Posters2020 RSNA Case Collection Necrotizing enterocolitisRSNA Case Collection2020Necrotizing enterocolitis RSNA Case Collection2020IntussusceptionRSNA Case Collection2020 Vol. 28, No. 1 Metrics Altmetric Score PDF download

Microvascular destruction identifies murine allografts that cannot be rescued from airway fibrosis

Small airway fibrosis (bronchiolitis obliterans syndrome) is the primary obstacle to long-term survival following lung transplantation. Here, we show the importance of functional microvasculature in the prevention of epithelial loss and fibrosis due to rejection and for the first time, relate allograft microvascular injury and loss of tissue perfusion to immunotherapy-resistant rejection. To explore the role of alloimmune rejection and airway ischemia in the development of fibroproliferation, we used a murine orthotopic tracheal transplant model. We determined that transplants were reperfused by connection of recipient vessels to donor vessels at the surgical anastomosis site. Microcirculation through the newly formed vascular anastomoses appeared partially dependent on VEGFR2 and CXCR2 pathways. In the absence of immunosuppression, the microvasculature in rejecting allografts exhibited vascular complement deposition, diminished endothelial CD31 expression, and absent perfusion prior to the onset of fibroproliferation. Rejecting grafts with extensive endothelial cell injury were refractory to immunotherapy. After early microvascular loss, neovascularization was eventually observed in the membranous trachea, indicating a reestablishment of graft perfusion in established fibrosis. One implication of this study is that bronchial artery revascularization at the time of lung transplantation may decrease the risk of subsequent airway fibrosis.

Secretion of Angiogenic Proteins by Human Multipotent Mesenchymal Stromal Cells (MSC) under Hypoxic Culture Conditions and Clinical Application of MSC in Steroid Induced Osteonecrosis in Children.

Osteonecrosis is a frequent complication after treatment for childhood leukemia.17% of adolescents above the age of 15 years treated in the ALL-BFM 95 trial protocol suffered from avascular necrosis of the bone (AVN). In addition, children receiving steroid-based treatment, e. g. autoimmune diseases, are frequently affected as well. If conservative measures fail, core decompression surgery is required. The success rate of surgery varies depending on the stage from 29% to 84% (Castro et al., 2000). Evidently, improved intervention strategies are warranted. Therefore, we evaluated the safety of implanting autologous MSC during surgical intervention in order to improve bone regeneration. AVN represent an area of absent blood perfusion and consequently low supplies of nutrients and oxygen. Therefore, we cultivated MSC under oxygen tensions of 3% or lower. These cells showed slowed proliferation and differentiation into bone. However, MSC grown under these low-oxygen conditions secreted significant amounts of vascular endothelial derived factor and selected insulin-like growth factors and their binding proteins. These factors might facilitate reperfusion and regeneration of bone at the site of implantation during core decompression surgery. 10 ml of heparinized bone marrow was drawn from the iliac crest of the patient. MSC were expanded under GMP conditions without the use of animal proteins employing platelet lysate and human fresh frozen plasma as source for growth factors (Müller et al., 2006). Recombinant trypsin was used for detachment and harvest of the cells. MSC could be expanded from 5 out of 5 juvenile bone marrow aspiates. Within three weeks of culture, sufficient numbers of cells, i. e. 112·106 ± 67·106, were generated in a certified GMP lab. At each of the three passages diagnostic cultures for aerobic bacteria were established and remained sterile throughout the culture period. MSC grown under these conditions were able to differentiate into osteoblasts. No chromosomal aberrations were detected by matrix-based comparative genomic hybridization using DNA microarrays containing >6,400 genomic DNA fragments. At the day of core decompression surgery, cells were harvested and resuspended to a final volume of 3 ml in saline. As core decompression implies drilling a hole into the necrotic area, the MSC were implanted through the same channel, which was sealed thereafter. Hence, instillation of the MSC did not require additional surgical procedures. Application of MSC was feasible and successful during core decompression surgery in all of the 5 patients. Follow up of the patients is between 14 and 8 months. None of the patients experienced adverse side effects, most importantly, there were no infectious complications. Clinically, no patient deteriorated and all patients reported less or no pain two months after surgery. Although the number of patients in this pilot trial is small, initial data for safety and feasibility of employing MSC in juvenile steroid-induced osteonecrosis is very promising.

Limitations of brain death in the interpretation of computed tomographic angiography

Sir: I suggest that in their recent publication “Limitations of computed tomographic angiography in the diagnosis of brain death”, Quesnel et al. make a profound discovery [1]. They report that of 21 adults with brain death (BD) diagnosed by accepted clinical tests and confirmatory electroencephalogram, computed tomographic angiography (CT-a) confirmed BD in only 11 patients (52.4%; 95% CI 30.4–73.6) [1]. Similarly, Leclerc et al. found 7/15 (46%) of clinically brain-dead patients had blood flow in the major branches of the circle of Willis by CT-a [2]. Perhaps more telling, Combes et al. found that 13/43 (30%) of clinically brain-dead patients with absent conventional angiographic brain blood flow had persistent cerebral perfusion by CT-a [3]. The interpretation offered for these findings is that CT-a is not appropriate to confirm BD because of a lack of sensitivity for BD. This interpretation is problematic. A more obvious interpretation would be that current clinical and ancillary tests for BD are not specific. In other words, when a patient is declared brain-dead by currently accepted clinical tests, supplemented by electroencephalogram or angiography if required, it is still uncertain that their entire brain is dead. Other findings support this as the more likely explanation for the CT-a findings. For example, not all brain functions are lost when BD is declared. It is known that, in patients correctly diagnosed with BD, there is lack of diabetes insipidus in 50%; electroencephalogram activity, brainstem-evoked potential activity, brain blood flow, and lack of pathologic destruction of brain in 5–20%; and in some cases respiratory activity at a PaCO2 > 60 mmHg [4]. In one study, five of nine patients without clinical BD had no brain blood flow on radionuclide angiography (but did not undergo CT-a) [5]. Another report documents a case of BD with absent angiographic brain blood flow, but with radionuclide brain blood flow [6]. Alternative explanations offered, such as cerebral reperfusion after intracranial pressure falls, decompressing cranial fractures or shunts, extracranial herniation of intracranial vessels, and jugular vein reflux [7], are unlikely to explain the high proportion of brain-dead patients with early CT-a multiple arterial brain blood flow. Moreover, the suggestion that “intracranial pressure may be insufficient to completely stop cerebral perfusion” is likely correct [1]. This explanation however, does not solve the dilemma. Complete circulatory arrest to the brain due to absent cerebral perfusion pressure is the purported pathophysiology of BD, accounting for the suggestion that all critical functions of the brain are irreversibly absent when BD is diagnosed. The findings from CT-a suggest otherwise. References

Abstract 3013: Myocardium at Risk of Infarction during Acute Ischemia is Accurately Measured after Revascularization by MRI in Humans

PURPOSE: The size of an infarct caused by coronary occlusion mainly depends on the duration of ischemia and the size of the ischemic myocardium, called myocardium at risk (MaR). T2-STIR imaging (visualizing oedema) has been shown to depict MaR in dogs. However, this has not been validated in humans. Therefore the purpose of this study was to validate the measurement of MaR by MRI against SPECT. METHODS: 7 patients (69±8 years, all male) with ST-elevation infarction treated by PCI were included. Technetium-labelled tetrofosmin was injected during ongoing ischemia before opening of the occluded vessel. SPECT was performed after concluded PCI and cardiac MRI after 3±3 days. MaR was measured as absent perfusion on SPECT and oedema on MRI, and expressed in percent of the left ventricular myocardium. The observer of the MRI data was blinded to the SPECT results. The localisation of transmural ischemia by the two methods was compared by visual assessment. RESULTS: The difference between SPECT and MRI for measurement of MaR was 0±9 % (mean±SD). The localization of transmural ischemia agreed between the two methods (Fig. 1 ) and expressed on vessel basis, MRI and SPECT showed 100 % concordant results. CONCLUSIONS: This study has showed for the first time in humans that T2-STIR accurately can determine myocardium at risk. This can be used in clinical research when studying new therapies for reducing infarct size. Fig 1 : Short axis slices of left ventricle showing inferior defect on SPECT (arrows, left panel) corresponding to the oedema signal on T2-STIR MRI (arrows, middle panel). For comparison, delayed enhancement in right panel shows subendocardial infarction (arrows).

The role of CnTI‐SonoVue in the diagnosis of ovarian masses with papillary projections: a preliminary study

To describe sonographically the distribution patterns of a second-generation contrast agent in the microcirculation of unilocular and multilocular ovarian masses with papillary projections, and to investigate whether qualitative evaluation of the passage of the contrast agent can improve the performance of sonography in distinguishing between benign and malignant masses with papillary projections. Thirty-three patients with unilocular or multilocular ovarian masses with papillary projections were enrolled into the study in three clinical centers. The contrast-enhanced transvaginal examination was performed using 'Contrast Tuned Imaging' (CnTI) technology and SonoVue ultrasound contrast agent. Twenty-four (73%) lesions were benign, eight (24%) were borderline ovarian tumors, and one patient presented with an endometrioid ovarian adenocarcinoma. On color and power Doppler examinations the presence of vessels was demonstrated in 17 papillary projections, while on CnTI-SonoVue examination, the presence of vessels was shown in these 17 and in six additional cases. In all cases with absent papillary perfusion after SonoVue intravenous injection, the cyst wall appeared unequivocally regular. The sensitivity and specificity of conventional color Doppler examination with regard to malignancy were 100% and 67% and the positive and negative likelihood ratios were 3.03 and 0.16, respectively. For the contrast-enhanced examination the corresponding values were 100%, 42%, 1.7 and 0.26. The difference in specificity was statistically significant (P<0.05) because 14 cases, in which papillary perfusion was detected after SonoVue injection, proved to be benign on pathological examination. Qualitative evaluation of blood circulation in papillary projections using CnTI-SonoVue examination does not improve the discrimination of benign from borderline/malignant ovarian masses with papillary projections.

Heating of bone and soft tissue by ultrasound

The absorption of ultrasound in human tissue always causes some local increase in temperature. In the case of ultrasound imaging, the power is usually much less than that used therapeutically and is unlikely to produce any significant physiological effect. However, a reliable means of calculating the maximum temperature rise to be expected in any given case will assist in both the development and the safe use of new ultrasound devices. To validate earlier work on ultrasonic tissue heating, including both experiment and finite element modelling (FEM), an analytical method is described for calculating the steady-state temperature rise along the axis of an axially symmetrical beam of ultrasound incident through water on a two-layer phantom consisting of agar gel and a bone mimic, the practical beam profile being modelled by a pair of coaxial Gaussian functions. It is shown that, in the absence of perfusion, the steady-state temperature distribution for the extended heat source generated by the ultrasound absorption can be obtained by integrating the point-source solution to the Bioheat transfer equation (BHTE). The boundary conditions associated with the difference in thermal properties of the mimic materials are satisfied by introducing images of the extended heat source in the gel/bone–mimic interface.

Imaging features of isolated unilateral pulmonary artery agenesis presenting in adulthood: a review of four cases

To highlight the variation in clinical manifestations, imaging and management of four cases of unilateral pulmonary artery agenesis presenting in adulthood. Four patients with unilateral pulmonary artery agenesis were referred to our institution between 1995 and 2005. They underwent a series of investigations, including chest radiography, echocardiography, ventilation perfusion scintigraphy, angiography, computed tomography (CT) and magnetic resonance imaging (MRI). Two of the four patients had absence of the right main pulmonary artery, whilst the remaining two patients had absence of the left main pulmonary artery. One patient showed a restrictive defect on pulmonary function tests. Two patients who had ventilation perfusion scintigraphy showed absent perfusion and reduced ventilation on the affected side. Angiography (where performed), CT and MRI confirmed the anatomy and the presence of multiple collaterals. Bronchiectasis was demonstrated on CT in two patients, with one also demonstrating a mosaic attenuation pattern. One patient had an incidental lung tumour on the side of the agenesis, which was diagnosed as a chondroid hamartoma on histology. Three of the four patients eventually underwent resection of the affected lung. Isolated unilateral pulmonary artery agenesis has a non-specific presentation. Awareness of this condition can lead to earlier diagnosis, with cross-sectional imaging making an important contribution.

Correlation of sonographic findings and outcome in necrotizing enterocolitis

There is little in the literature regarding the use of gray-scale and Doppler sonography of the bowel in necrotizing enterocolitis (NEC) and how findings depicted by this modality might assist in predicting outcome and influence management. To correlate sonographic findings with outcome in NEC. This was a retrospective analysis of clinical and abdominal ultrasonography (AUS) findings in NEC from January 2003 to December 2005. AUS findings were evaluated for portal venous gas, free gas, peritoneal fluid, bowel wall thickness, echogenicity, perfusion and intramural gas. Patients were categorized into two groups, according to their outcome. A total of 40 infants were identified who had AUS for NEC prior to any surgical intervention. Group A comprised 18 neonates treated medically and recovered fully, and group B comprised 22 neonates who required surgery or died. Free gas (six patients) and focal fluid collections (three patients) were only found in group B. Increased bowel wall echogenicity, absent bowel perfusion, portal venous gas, bowel wall thinning, bowel wall thickening, free fluid with echoes and intramural gas were seen in both groups, but more frequently in group B. Anechoic free fluid was seen more frequently in group A. Increased bowel perfusion was seen equally in both groups. An adverse outcome was associated with the sonographic findings of free gas, focal fluid collections or three or more of the following: increased bowel wall echogenicity, absent bowel perfusion, portal venous gas, bowel wall thinning, bowel wall thickening, free fluid with echoes and intramural gas. Sonographic findings are useful in predicting outcome and therefore might help guide management.

Single and cell population respiratory oscillations in yeast: A 2-photon scanning laser microscopy study

Two-photon scanning laser and confocal microscopies were used to image metabolic dynamics of single or cell populations of Saccharomyces cerevisiae strain 28033. Autofluorescence of reduced nicotinamide nucleotides, and mitochondrial membrane potential (ΔΨm), were simultaneously monitored. Spontaneous, large-scale synchronized oscillations of NAD(P)H and ΔΨm throughout the entire population of yeasts occurred under perfusion with aerated buffer in a continuous single-layered film of organisms. These oscillations stopped in the absence of perfusion and the intracellular NAD(P)H pool became reduced. Individual mitochondria within a single yeast also showed in-phase synchronous responses with the cell population, in both tetramethylrhodamine ethyl ester (or tetramethylrhodamine methyl ester) and autofluorescence. A single, localized, laser flash also triggered mitochondrial oscillations in single cells suggesting that the mitochondrion may behave as an autonomous oscillator. We conclude that spontaneous oscillations of S. cerevisiae mitochondrial redox states and ΔΨm occur within individual yeasts, and synchrony of populations of organisms indicates the operation of an efficient system of cell–cell interaction to produce concerted metabolic multicellular behaviour on the minute time scale in both cases.

Cryotherapy for Renal-Cell Cancer: Diagnosis, Treatment, and Contrast-Enhanced Ultrasonography for Follow-Up

Cryotherapy is a curative treatment option for patients with small (<4 cm) renal-cell cancers. For the followup of ablated lesions, imaging is the only available method, but the best tool has not yet been determined. The method selected should be able to determine the presence or absence of perfusion in the area and measure the lesion. Usually, contrast-enhanced CT or MRI is used. The accompanying video shows cryotherapy treatment along with contrast-enhanced ultrasound investigations before and afterward. We used a Siemens Acuson Sequoia device with contrast pulse sequence imaging and Sonovue (Bracco) as the contrast agent. The lesion could be identified and measured easily. Because this method enables selective detection of contrast, the presence and absence of perfusion can be determined objectively.

Acute testicular torsion in children: the role of sonography in the diagnostic workup

Acute testicular torsion in children is an emergency and has to be diagnosed urgently. Doppler sonography is increasingly used in imaging the acute scrotum. Nevertheless, in uncertain cases, surgical exploration is required. In this study, we attempted to define the role of Doppler sonography in the diagnostic workup of the acutely painful scrotum. All patients admitted between 1999 and 2005 with acute scrotal pain were included. After clinical assessment, patients were imaged by Doppler sonography with a ''high-end'' instrument. In cases of absent arterial perfusion of the testis in Doppler sonography, surgical exploration was carried out. Patients with unaffected perfusion were followed clinically by ultrasound for up to 2 years. Sixty-one infants and children aged 1 day to 17 years (median: 7.9 years) were included. In 14 cases, sonography demonstrated absent central perfusion, with abnormal parenchymal echogenicity in six. Absence of venous blood flow together with reduction of central arterial perfusion was found in one infant. In these 15 patients, surgical exploration confirmed testicular torsion. Among the other 46 patients, we found four cases with increased testicular perfusion and 27 with increased perfusion of the epididymis. In one infant, a testicular tumour was found sonographically, and orchiectomy confirmed diagnosis of a teratoma. Follow-up examinations of the conservatively treated patients showed good clinical outcome with physiologic central perfusion as well as normal echogenic pattern of both testes. No case of testicular torsion was missed. By means of Doppler sonography, an unequivocal statement regarding testicular perfusion was possible in all cases. The initial Doppler diagnosis was confirmed by operative evaluation and follow-up ultrasound. Testicular torsion can therefore be excluded by correctly performed ultrasound with modern equipment.

Alteration in choroidal blood flow produced by local pressure

To investigate how transient pressure applied to the retinal pigment epithelium (RPE) layer and choroid affects choroidal blood flow in rabbits. Twelve rabbits underwent vitrectomy and local retinectomy. In nine of the rabbits a glass rod was used to exert brief pressure on the RPE layer and choroid. Three of the rabbits had no pressure indentation and were considered to be controls. The choroidal circulation was studied by indocyanine green (ICG) angiography. The retina and choroid were studied by postmortem histology. Pressure on the RPE layer and choroid caused nonfluorescence in segments of retinal arteries and veins and reduced fluorescence in adjacent choroidal capillaries, producing a black region at the pressure site in the angiograms. The size of this region decreased during the angiogram, often accompanied by the appearance of fine channels considered to be flow through the partially blocked vessels; the obstructed ends of the vessels became increasingly hyperfluorescent. These changes lasted for about 24 h before the choroidal circulation recovered. Histology showed evidence of thrombotic-like material in choroidal arteries and veins at the areas of absent perfusion. After local retinectomies, there was no evidence of thrombosis in control eyes where no pressure had been applied. Brief pressure on the RPE and choroid causes immediate reduction in flow through choroidal vessels, which appears to be due to local thrombosis in small segments of these vessels that resolves slowly. This may reflect a tendency for thrombi to form rapidly in choroidal vessels; it may also depend on neural reflexes causing vasoconstriction. The long time course of recovery could result in retinal ischemia and may underlie the pathophysiology of other pressure insults to the choroid.

Characterization of the RF ablation-induced ‘oven effect’: The importance of background tissue thermal conductivity on tissue heating

Purpose: To determine the effect of background tissue thermal conductivity on RF ablation heating using ex vivo agar phantoms and computer modelling.Method: Two-compartment cylindrical agar phantom models (5% agar, 5% NaCl, 3% sucrose) were constructed. These included a standardized inner compartment (2 cm diameter, 4 cm length, 0.25% agar) representing a tumour, surrounded by an outer compartment representing background tissue. The thermal conductivity of the outer compartment was varied from 0.48 W m−1°C (normal liver) to 0.23 W m−1°C (fat) by adding a fat-saturated oil-based solute (10–90%) to the agar. RF ablation was applied at 2000 mA current for 2 min. Temperatures were recorded up to 4 cm from the electrode tip at 1 cm intervals. Subsequently, a 2-D finite element computer model was used to simulate RF ablation of 2–24 min duration for tumours measuring 2–4 cm in diameter surrounded by tissues of different thermal conductivity with the presence or absence of perfusion (0–5 kg m−3 s−1) (n = 44). A comparison of results was performed.Results: In agar phantoms, the amount of fat in the background tissue correlated with thermal conductivity as a negative exponential function (r2 = 0.98). Significantly increased temperatures were observed at the edge of the inner compartment (1 cm from the electrode tip) as the fat content of the outer compartment increased (p < 0.01). Thus, temperatures at 2 min measured 31.5 ± 2.2°C vs 45.1 ± 3.1°C for thermal conductivities of 0.46 W m−1°C (10% fat) and 0.23 W m−1°C (90% fat), respectively. On the other hand, higher levels of fat led to lower temperature increases in the background compartment (0.2 ± 0.3°C for 90% fat vs. 1.1 ± 0.05°C for 10% fat, p < 0.05). Phantom thermal heating patterns correlated extremely well with computer modelling (r2 = 0.93), demonstrating that background tissues with low thermal conductivity increase heating within the central tumour, particularly for longer durations of RF ablation and in smaller tumours. Furthermore, computer modelling demonstrated that increases in temperature at the tumour margin for background tissues of lower thermal conductivity persisted in the presence of perfusion, with a clinically relevant 4.5°C difference between background thermal conductivities of fat and soft tissue for a 3 cm tumour with perfusion of 2 kg m−3 s−1, treated for 12 min.Conclusion: Lower thermal conductivity of background tissues significantly increases temperatures within a defined ablation target. These findings provide insight into the ‘oven effect’ (i.e. increased heating efficacy for tumours surrounded by cirrhotic liver or fat) and highlight the importance of both the tumour and the surrounding tissue characteristics when contemplating RF ablation efficacy.

Elevated semicarbazide-sensitive amine oxidase (SSAO) activity in lung with ischemia–reperfusion injury: Protective effect of ischemic preconditioning plus SSAO inhibition

Ischemic preconditioning (IP) has been shown to protect the lung against ischemia–reperfusion (I/R) injury. Although the production of reactive oxygen species (ROS) has been postulated to play a crucial role in I/R injury, the sources of these radicals in I/R and the mechanisms of protection in IP remain unknown. Since it was postulated that deamination of endogenous and exogenous amines by semicarbazide-sensitive amine oxidase (SSAO) in tissue damage leads to the overproduction of hydrogen peroxide (H 2O 2), we investigated the possible contribution of tissue SSAO to excess ROS generation and lipid peroxidation during I/R and IP of the lung. Male Wistar rats were randomized into 6 groups: control lungs were subjected to 30 min of perfusion in absence and presence of SSAO inhibitor, whereas the lungs of the I/R group were subjected to 2 h of cold ischemia following the 30 min of perfusion in absence and presence of SSAO inhibitor. IP was performed by two cycles of 5 min ischemia followed by 5 min of reperfusion prior to 2 h of hypothermic ischemia in absence and presence of SSAO inhibitor. Lipid peroxidation, reduced (GSH) and oxidized (GSSG) glutathione levels, antioxidant enzyme activities, SSAO activity, and H 2O 2 release were determined in tissue samples of the study groups. Lipid peroxidation, glutathione disulfide (GSSG) content, SSAO activity and H 2O 2 release were increased in the I/R group, whereas GSH content, GSH / GSSG ratio and antioxidant enzyme activities were decreased. SSAO activity, H 2O 2 release, GSSG content and lipid peroxidation were markedly decreased in the IP group, whereas GSH content, GSH / GSSG ratio and antioxidant enzyme activities were significantly increased. SSAO activity was found to be positively correlated with H 2O 2 production in all study groups. Increased lipid peroxidation, SSAO activity, GSSG and H 2O 2 contents as well as decreased GSH and antioxidant enzyme levels in I/R returned to their basal levels when IP and SSAO inhibition were applied together. The present study suggests that application of IP and SSAO inhibition together may be more effective than IP alone against I/R injury in the lung.

Necrotizing Enterocolitis: Assessment of Bowel Viability with Color Doppler US

To determine whether absence of bowel wall perfusion at color Doppler ultrasonography (US) is indicative of bowel necrosis in neonates with necrotizing enterocolitis (NEC). This study was approved by the research ethics board, and informed consent was obtained. Sixty-two neonates enrolled in the prospective study underwent US of the bowel wall. Neonates were divided into two groups. Group A included 30 control subjects with gestational ages (GAs) ranging from 24 to 41 weeks. Group B included 32 neonates with GAs ranging from 24 to 40 weeks who were clinically proved to have or suspected of having NEC. All neonates in group B underwent abdominal radiography. Normative values were calculated in group A. In group B, the sensitivities and specificities of color Doppler US and abdominal radiography for detection of bowel necrosis were computed by using the modified Bell staging criteria for NEC as the reference standard. Two neonates were excluded from group B; thus, a total of 60 neonates were included in the study. In group A, bowel wall thickness ranged from 1.1 to 2.6 mm. Bowel wall perfusion was detected with color Doppler US in all 30 neonates. Color Doppler signals ranged from one to nine dots per square centimeter. Twenty-two of 30 neonates in group B received a diagnosis of NEC. Mild to moderate NEC was diagnosed in 12 neonates. Color Doppler US depicted an isolated segment of bowel-absent blood flow in two neonates; this finding was confirmed with laparotomy. In 10 neonates with severe NEC, color Doppler US depicted isolated or multiple segments of bowel with absent perfusion. Pneumoperitoneum was present in only four neonates. The remaining eight neonates at risk for NEC had no evidence of loops without perfusion at color Doppler US. The sensitivity of free air at abdominal radiography as a positive sign for severe NEC with necrotic bowel was 40% compared with the 100% sensitivity of absence of flow at color Doppler US (P = .03). Color Doppler US is more accurate than abdominal radiography in depicting bowel necrosis in NEC.

Post-systolic shortening during dobutamine stress echocardiography predicts cardiac survival in patients with severe left ventricular dysfunction

Patients with severe left ventricular dysfunction and myocardial viability by dobutamine stress echocardiography (DSE) or F18-fluorodeoxyglucose-single-photon emission computed tomography (FDG-SPECT), experience improved survival after coronary revascularization. Pulsed wave-tissue Doppler imaging (PW-TDI)-derived ejection phase shortening (EPS) and post-systolic shortening (PSS) velocities may help to quantify DSE. We assessed these variables in a prospective long-term follow-up. Eighty patients (58 men, mean age 63+/-9 years) with left ventricular dysfunction (radionuclide ventriculography mean ejection fraction, 34+/-11%) underwent both DSE and FDG-SPECT for myocardial viability. Viable myocardium was improvement from rest to low dose or worsening of wall motion at peak DSE and normal perfusion, mildly reduced perfusion with FDG uptake or severely reduced or absent perfusion with increased FDG uptake (mismatch) at FDG-SPECT. EPS, PSS velocities and EPS/PSS ratio during DSE were analysed using a six-segment model. Coronary revascularization bypass grafting was performed in 62 patients. All patients completed a long-term (9-year) follow-up for cardiac death. The segmental prevalence of severe dyssynergy was 77%. On a patient basis myocardial viability was detected by EPS/PSS ratio (31%), FDG-SPECT (34%) and DSE (26%). A significant improvement of Kaplan-Meier survival was predicted in viable compared with nonviable revascularized patients (P < 0.01). Both EPS/PSS ratio and FDG-SPECT, compared to DSE alone, tended to allocate more accurately univariate prediction of death-free outcome (odds ratio, 2.5 and 2.7 compared with 2.1). TDI adds objective variables to DSE, helping to recognize viable myocardium and optimize prediction of death-free outcome in long-term follow-up, with favorable comparison with nuclear techniques.

Impact of diabetes mellitus on myocardial perfusion after primary angioplasty in patients with acute myocardial infarction

We investigated the impact of diabetes mellitus on myocardial perfusion after primary percutaneous coronary intervention (PCI) utilizing myocardial blush grade (MBG) and ST-segment elevation resolution (STR). Diabetes is an independent predictor of outcomes after primary PCI for acute myocardial infarction (AMI). Whether the poor prognosis is due to lower rates of myocardial reperfusion is unknown. Reperfusion success in those with and without diabetes mellitus was determined by measuring MBG (n = 1,301) and STR analysis (n = 700) in two substudies of the Controlled Abciximab and Device Investigation to Lower Late Angioplasty Complications (CADILLAC) trial among patients undergoing primary PCI for AMI. There were no differences between those with or without diabetes with regard to postprocedural Thrombolysis In Myocardial Infarction (TIMI) flow grade 3 (>95%), distribution of infarct-related artery, and the frequency of stent deployment or abciximab administration. Patients with diabetes mellitus were more likely to have absent myocardial perfusion (MBG 0/1, 56.0% vs. 47.1%, p = 0.01) and absent STR (20.3% vs. 8.1%, p = 0.002). Diabetes mellitus (hazard ratio [HR] 1.63 [95% confidence interval (CI) 1.17 to 2.28], p = 0.004) was an independent predictor of absent myocardial perfusion (MBG 0/1) and absent STR (HR 2.94 [95% CI 1.64 to 5.37], p = 0.005) by multivariate modeling. Despite similar high rates of TIMI flow grade 3 after primary PCI in patients with and without diabetes, patients with diabetes are more likely to have abnormal myocardial perfusion as assessed by both incomplete STR and reduced MBG. Diminished microvascular perfusion in diabetics after primary PCI may contribute to adverse outcomes.

The Role of “Dormant” Mechanisms in Regulation of K/Na Balance in the Rat Cardiac Muscle Cell during Hypoxia

Using the electron probe microanalysis, potassium and sodium concentrations were measured in Wistar rat cardiac muscle cells. Hypoxic conditions were modeled according to the protocol of global ischemia in the absence of perfusion or via anoxic perfusion without glucose. It was shown that depending on the scheme of realization of hypoxia the change with time of the intracellular potassium and sodium balance had different character. Based on the obtained data, the sequence of activation of the hypoxia-specific mechanisms of ion transport on the cardiomyocyte membrane is considered.