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T Juvonen

Publications and source records attributed to T Juvonen.

At least 55 records · Page 3Linked to original sources
PubMed1998

Retrograde cerebral perfusion enhances cerebral protection during prolonged hypothermic circulatory arrest: a study in a chronic porcine model.

BACKGROUND: This study was undertaken to confirm earlier findings that retrograde cerebral perfusion (RCP) can improve cerebral outcome after prolonged hypothermic circulatory arrest (HCA), and to determine whether RCP with inferior vena caval occlusion, which is more effective in removing particulate emboli, is superior to conventional RCP in enhancing cerebral protection. METHODS: Sixty-two pigs (27 to 30 kg) were randomly assigned to undergo one of the following for 90 minutes at 20 degrees C: antegrade cerebral perfusion (ACP); conventional RCP (RCP); RCP with occlusion of the inferior vena cava (RCP-O), or HCA with the head packed in ice. RCP flow was regulated to a sagittal sinus pressure of 20 mm Hg. Hemodynamic, electrophysiologic, and metabolic monitoring were carried out until 4 hours after rewarming, daily behavioral and neurologic assessments until elective sacrifice on day 7, and histologic analysis of the brain after death. RESULTS: Complete behavioral recovery was seen in all surviving animals by day 5 after ACP or RCP, but in only 83% after RCP-O and 50% after HCA (p = 0.001). A histopathologic score of 2 or more, indicating more than mild injury, was not found in any animal after ACP, in 27% after RCP, in 47% after HCA, and in 68% after RCP-O (p = 0.002). The median oxygen consumption was 6.66 mL/min after ACP, 1.37 mL/min with RCP, and 1.02 mL/min with RCP-O (p < 0.0001). The median amount of fluid sequestered was 2,450 mL after RCP-O, 760 mL after RCP, and -200 mL after ACP (p < 0.0001). CONCLUSIONS: Conventional RCP without inferior vena caval occlusion results in a significantly better outcome than RCP-O after prolonged HCA, despite more efficient cerebral perfusion during RCP-O, and also provides cerebral protection superior to prolonged HCA alone, but care must be taken during its implementation to minimize cerebral edema and other possible causes of retroperfusion-related cerebral injury.

Animals↗
PubMed1998

Computed tomographic evaluation of retrosternal adhesions after pericardial substitution.

BACKGROUND: Reoperative median sternotomy can result in cardiac injury and serious bleeding, with the rate ranging from 2% to 6%. Closure of the native pericardium can maintain a preventing plane of cleavage. In patients in whom primary pericardial closure is not possible, several substitutes have been tried with variable results. We conducted a prospective study to evaluate the clinical feasibility of polytetrafluoroethylene and polyglycolic acid patches as pericardial substitutes, using computed tomography for imaging the postoperative state of the retrosternal space. METHODS: The basic population comprised 540 patients who were scheduled for coronary artery bypass grafting, and 52 of them who met the research criteria were chosen for computed tomographic evaluation after 5 years after the primary operation. RESULTS: As a substitute, polytetrafluoroethylene seemed to be less adhesive to the posterior surface of the sternum. Total adhesion scores were also statistically significant (p < 0.001) to the advantage of polytetrafluoroethylene over polyglycolic acid as a pericardial substitute. CONCLUSIONS: Polytetrafluoroethylene membrane seems to be capable of minimizing retrosternal adhesion formation and thus it may protect the heart during subsequent reoperative sternotomy.

Coronary Artery Bypass↗
PubMed1998

Can retrograde perfusion mitigate cerebral injury after particulate embolization? A study in a chronic porcine model.

OBJECTIVE: We assessed the impact on histologic and behavioral outcome of an interval of retrograde cerebral perfusion after arterial embolization, comparing retrograde cerebral perfusion with and without inferior vena caval occlusion with continued antegrade perfusion. METHODS: Sixty Yorkshire pigs (27 to 30 kg) were randomly assigned to the following groups: antegrade cerebral perfusion control; antegrade cerebral perfusion after embolization; retrograde cerebral perfusion control; retrograde cerebral perfusion after embolization; retrograde cerebral perfusion with inferior vena cava occlusion, retrograde cerebral perfusion with inferior vena cava occlusion control, and retrograde cerebral perfusion with inferior vena cava occlusion after embolization. After cooling to 20 degrees C, a bolus of 200 mg of polystyrene microspheres 250 to 750 (microm diameter (or saline solution) was injected into the isolated aortic arch. After 5 minutes of antegrade cerebral perfusion, 25 minutes of antegrade cerebral perfusion, retrograde cerebral perfusion, or retrograde cerebral perfusion with inferior vena cava occlusion was instituted. After the operation, all animals underwent daily assessment of neurologic status until the time of death on day 7. RESULTS: Aortic arch return, cerebral vascular resistance, and oxygen extraction data during retrograde cerebral perfusion showed differences, suggesting that more effective flow occurs during retrograde cerebral perfusion with inferior vena cava occlusion, which also resulted in more pronounced fluid sequestration. Microsphere recovery from the brain revealed significantly fewer emboli after retrograde cerebral perfusion with inferior vena cava occlusion. Behavioral scores showed full recovery in all but one control animal (after retrograde cerebral perfusion with inferior vena cava occlusion) by day 7 but were considerably lower after embolization, with no significant differences between groups. The extent of histopathologic injury was not significantly different among embolized groups. Although no histopathologic lesions were present in either the antegrade cerebral perfusion control group or the retrograde cerebral perfusion control group, mild significant ischemic damage occurred after retrograde cerebral perfusion with inferior vena cava occlusion even in control animals. CONCLUSIONS: Although effective washout of particulate emboli from the brain can be achieved with retrograde cerebral perfusion with inferior vena cava occlusion, no advantage of retrograde cerebral perfusion with inferior vena cava occlusion after embolization is seen from behavioral scores, electroencephalographic recovery, or histopathologic examination; retrograde cerebral perfusion with inferior vena cava occlusion results in greater fluid sequestration and mild histopathologic injury even in control animals. Retrograde cerebral perfusion with inferior vena cava occlusion shows clear promise in the management of embolization, but further refinements must be sought to address its still worrisome potential for harm.

Animals↗
PubMed1998

Chronic inflammation and elastin degradation in abdominal aortic aneurysm disease: an immunohistochemical and electron microscopic study.

OBJECTIVES: To investigate (i) elastin degradation and the possible association between proteolysis and inflammation in abdominal aortic aneurysm disease (AAA), and (ii) the presence of cytomegalovirus (CMV) infection in the walls of AAA. MATERIALS: Specimens from 12 infrarenal AAAs, eight aortas with occlusive disease (AOD) and two normal aortas were studied by conventional light microscopy, immunohistochemistry using a monoclonal anti-elastin antibody BA-4 and anti-CMV antibody and transmission electron microscopy (TEM). MAIN RESULTS: In AAA the decrease in elastin immunoreactivity and the presence of elastin degradation was associated with increased mononuclear inflammatory cell infiltrates (p = 0.004 and p = 0.00002, respectively). The CMV immunostainings of the normal aortic wall and all the AAA and AOD samples were negative, nor could any CMV particles be demonstrated by TEM. CONCLUSIONS: The chronic inflammation and degradation of elastin in AAA suggests a possible immune-mediated mechanism. The inflammation may be induced by the chemotactic properties of elastin-derived peptides.

Adult↗
PubMed1998

Ultrastructural changes in myocardium during mild hypothermic retrograde blood cardioplegia.

Uniformity of myocardial protection during retrograde blood cardioplegia is still a controversial area. We conducted a study on electron microscopic changes in the myocardium during mild hypothermic retrograde cardioplegia (31-32 degrees C) in 12 patients undergoing coronary artery bypass grafting. Biopsies for electron microscopy were taken from the right and left ventricular myocardium before and at the end of aortic cross-clamping and after 15 min reperfusion. The intercellular junctions, intracellular and extracellular oedema, mitochondria, capillaries, nuclei and myofibrils were analysed separately in each specimen, using a semiquantative method with scoring from 0 (unchanged) to 3 (severe changes), and the total scores were correlated with the severity of right and left coronary artery disease and with ischaemia time during aortic cross-clamping. Mild to moderate ultrastructural changes occurred in the myocardium during the cardiopolegia, most typically myofibrillar injury and oedema. These changes increased during aortic cross-clamping and reperfusion, especially in the right ventricle. The total ultrastructural score for the right ventricle correlated negatively with the severity of right coronary artery disease at the end of cross-clamping. No such correlation was found in the left ventricle. Apart from one case of perioperative myocardial infarction, the clinical outcome was unproblematic. Myocardial structure thus was by and large well preserved during mild hypothermic retrograde blood cardioplegia, with the right ventricle seemingly somewhat less protected than the left.

Biopsy↗
PubMed1998

Options for the management of poststernotomy mediastinitis.

The management of 27 consecutive deep sternotomy wound infections is reviewed. In 22 cases the initial treatment was debridement, sternal refixation and dilute antibiotic irrigation via multiple irrigation-suction catheters. In the nine cases (41%) in which these measures failed, more extensive sternal and costal cartilage debridement and closure with a muscle flap were performed. Five cases were initially managed with major reconstructive surgery. For reconstruction, a bilateral pectoralis major myocutaneous flap was used alone in eight cases, while in six the flap was insufficient to obliterate the whole poststernectomy space, and was supplemented with rectus abdominis muscle. Early mediastinitis can be effectively treated with thorough wound debridement and mediastinal irrigation, but if there is a two-week delay from the initial sternotomy to manifestation of infection, radical debridement with muscle flap closure should be seriously considered.

Aged↗
PubMed1998

Pericardial closure with polytetrafluoroethylene surgical membrane or biodegradable polyglycolic acid mesh after coronary artery bypass surgery--a baseline report.

BACKGROUND AND AIMS: Complete and tight closure of the native pericardium may kink or even occlude bypass grafts after coronary artery bypass grafting (CABG) and therefore the feasibility of tight closure has been debated. The growing number of reoperations has raised the question how to reduce the risk of damage of the right ventricle and patent grafts. We are performing a prospective randomized trial aiming to evaluate the feasibility of polytetrafluoroethylene (PTFE) surgical membrane and biodegradable polygycolic acid (PGA) mesh as pericardial substitutes for closure purposes in patients undergoing primary isolated CABG surgery. MATERIAL AND METHODS: The series comprises 540 patients who underwent a primary isolated CABG procedure at the Oulu University Hospital from October 1989 to May 1994. RESULTS AND CONCLUSIONS: The baseline results suggest that the PTFE and PGA materials seem to be similar despite the subtle early expression of tamponade related to the PTFE membrane after postoperative bleeding.

Adult↗
PubMed1998

Angiogenesis is associated with mononuclear inflammatory cells in abdominal aortic aneurysms.

BACKGROUND AND AIMS: To evaluate the extent of neovascularisation in abdominal aortic aneurysms, specimens from the aneurysm walls of 17 consecutive patients (14 men, mean age 69 years, range 59 to 79 years) were studied and compared with specimens from patients with aortoiliac occlusive disease (n = 8, five men, mean age 53 years; range 40 to 71 years). Routine histology was performed after haematoxylin and eosin, Verhoeff's elastic and periodic acid-Schiff stainings. For immunophenotypic analysis of inflammatory cells four monoclonal mouse antibodies (UCHL1, L26, PG-M1 and KP1) were used. RESULTS: The histological sections through the walls of the AAAs showed extensive destruction of elastin and variable inflammation. Dense neovascularisation was seen throughout the aortic wall in the AAA cases compared to a mild angiogenetic response seen only occasionally in the AODs. CONCLUSIONS: Angiogenesis may play a significant role in the AAA process by recruiting and carrying a macrophage-rich infiltrate to the aortic wall.

Aged↗
PubMed1997

Prospective study of the natural history of thoracic aortic aneurysms.

BACKGROUND: The decision whether or not to recommend resection of moderately large descending thoracic and thoracoabdominal aneurysms requires weighing the relatively high mortality and significant risk of paraplegia associated with operation against the likelihood that the aneurysm will rupture spontaneously, with an almost invariably fatal outcome. To better define the risk of aneurysm rupture, we undertook a prospective study of patients who had not had operation on their moderately large descending thoracic and thoracoabdominal aneurysms. METHODS: Patients were enrolled at the time of their second computed tomographic scans: three-dimensional computer-generated reconstructions allowed determination of several dimensional parameters for each study, including diameters and cross-sectional areas at the site of maximal dilatation in the descending aorta and in the abdomen as well as total thoracoabdominal surface area. Comparisons of serial studies permitted calculation of yearly rates of change in these dimensions. RESULTS: Of 114 patients, 8 died of causes unrelated to the aneurysm, 26 died of rupture, 20 met previously determined criteria for operation, and 60 survived without operation or rupture. Multivariate regression analysis identified maximal diameter in the descending and in the abdominal aorta as independent risk factors for rupture, as well as older age, the presence of even uncharacteristic pain, and a history of chronic obstructive pulmonary disease. A piecewise exponential model enabled construction of an equation allowing calculation of rate of rupture in patients in whom the values of the risk factors are known, and also of the probability of rupture in a given individual over a specified time interval. CONCLUSIONS: Because using this equation--based on easily determined risk factors (age, pain, chronic obstructive pulmonary disease, maximal thoracic and maximal abdominal aortic diameter)--allows the risk of aneurysm rupture within a given interval to be estimated fairly accurately for each individual patient, it is our current practice to recommend operation when the calculated risk of rupture within 1 year exceeds the anticipated mortality of elective operation, rather than relying on general operative guidelines based almost exclusively on aneurysm size.

Adult↗
PubMed1997

Detection of Chlamydia pneumoniae in human nonrheumatic stenotic aortic valves.

OBJECTIVES: We sought to study the possible presence of Chlamydia pneumoniae in aortic valve stenosis (AVS). BACKGROUND: Inflammation and immune mechanisms are considered important for the pathogenesis of nonrheumatic AVS. All chlamydial species are able to cause heart infections, and seroepidemiologic studies have indicated an association between chronic C. pneumoniae infection and coronary artery disease. Furthermore, the organism has been demonstrated in atherosclerotic lesions. METHODS: Aortic valve specimens with varying degrees of macroscopic disease were obtained from 35 subjects--17 consecutive patients undergoing aortic valve replacement for treatment of nonrheumatic AVS and 18 age-matched subjects at autopsy. The possible presence of C. pneumoniae in aortic valves was studied by immunohistochemical analysis, polymerase chain reaction or transmission electron microscopy, or a combination of these. RESULTS: Positive immunohistochemical staining with C. pneumoniae specific antibody was found in 9 (53%) of 17 patients with advanced aortic valve disease requiring surgical treatment (group A), 8 (80%) of 10 cadavers with clearly macroscopic aortic valve pathology (group B) and 1 (12%) of 8 grossly normal cadaver control subjects (group C). Statistical significance with regard to the presence of C. pneumoniae was found when combined diseased subjects (groups A and B: total 17 of 27 subjects) were compared with group C (p = 0.018). However, when group A was compared with group C, there was only marginal statistical significance (p = 0.088). Finally, there was a strong statistical significance (p = 0.015) when groups B and C were compared. Chlamydia pneumoniae DNA was also found in three stenotic valves, and in two of the three tested valve specimens chlamydia-like particles were seen by electron microscopy. CONCLUSIONS: Chlamydia pneumoniae is frequently present in nonrheumatic AVS. Similarly, the high number of C. pneumoniae infections detected in the early lesions of "degenerative" AVS suggest that this pathogen may play an etiologic role in the development of this disease. The validity of this relation requires additional study.

Aged↗
PubMed1997

Tenascin expression is associated with a chronic inflammatory process in abdominal aortic aneurysms.

PURPOSE: This study was performed to test whether tenascin, a large oligomeric glycoprotein of the extracellular matrix, is present in AAA disease and whether it could play a pathophysiologic role in the development of this disease. METHODS: Tenascin immunoreactivity was investigated from samples of the aneurysmal walls of 17 patients with AAAs, and the results were compared with the results of those of six patients with aortoiliac occlusive disease (AOD) and one normal control patient. To study the source of tenascin mRNA synthesis, some tissue samples were also examined with a tenascin RNA probe by in situ hybridization. RESULTS: The difference in immunoreactivity between the AODs and AAAs was especially prominent in the adventitial layer, where the specimens from AAAs displayed strong diffuse and reticular immunostaining. In AAAs the immunostaining was clearly associated with the degree of mononuclear inflammatory cell infiltrate and with the neovascularization of the adventitial layer. CONCLUSION: Tenascin expression is evident in AAA disease and is distinctly associated with mononuclear inflammatory cells. The adhesive properties of tenascin may offer a relevant explanation for the mechanism by which monocytes transmigrate into the aortic wall. The definitive role of tenascin in AAA process may be more complex, however, and will necessitate further investigation.

Adult↗
PubMed1997

Aminoterminal propeptide of type III procollagen in the follow-up of patients with abdominal aortic aneurysms.

PURPOSE: We evaluate here whether serial changes in the concentration of the aminoterminal propeptide of type III procollagen (PIIINP) in serum bear any relationship to the rate of abdominal aortic aneurysm (AAA) expansion and whether serum PIIINP has any predictive value with respect to the rupture event. METHODS: One hundred thirty-nine patients with asymptomatic AAAs were followed-up at intervals of 6 to 12 months by means of a clinical examination, B-mode ultrasound scan, and serum markers of collagen metabolism. Similar laboratory samples were also obtained from 18 patients who had a rupture of the AAA as their primary symptom soon after onset. RESULTS: The primary correlation between serum PIIINP and AAA diameter was 0.22 (p = 0.01), and that between serum PIIINP and the thickness of the thrombus was 0.49 (p = 0.001). Toward the end of the follow-up, however, the correlation increased to 0.55 (p = 0.002) for serum PIIINP and diameter, but remained at 0.42 (p = 0.02) for serum PIIINP and the thickness of the thrombus. Serum PIIINP values were very high among the 18 patients who had ruptured AAAs. CONCLUSIONS: Acceleration of AAA growth is reflected in serum PIIINP, and a marked elevation of serum PIIINP during follow-up of a patient with an AAA may predict an approaching rupture event.

Aged↗
PubMed1997

Demonstration of Chlamydia pneumoniae in the walls of abdominal aortic aneurysms.

BACKGROUND: Seroepidemiologic studies have indicated an association between chronic Chlamydia pneumoniae infection and coronary heart disease. The organism, which is a common respiratory pathogen, has been demonstrated in atherosclerotic lesions of the aorta and coronary arteries. Abdominal aortic aneurysms are frequently associated with atherosclerosis, and inflammation may actually be an important factor in aneurysmal dilatation. Hence it could be assumed that C. pneumoniae may play a role in maintaining an inflammation and triggering the development of aortic aneurysms. METHODS AND RESULTS: Specimens from abdominal aortic aneurysm were examined for the presence of C. pneumoniae by immunohistochemical analysis, the polymerase chain reaction amplifying omp 1 gene, transmission electron microscopy, and culture methods with histologically atherosclerosis-negative human aortic tissues used as a control group. Chlamydial lipopolysaccharide and C. pneumoniae specific antigens were found by immunohistochemistry in 12 and 8 of 12 aneurysm specimens, respectively, and C. pneumoniae DNA could be demonstrated in 6 of 6 aneurysm specimens studied. Furthermore electron microscopy revealed the presence of Chlamydia-like elementary bodies in three of four aneurysm specimens tested. None of the control samples gave positive reaction in the polymerase chain reaction, and C. pneumoniae antigens were not detected in any of them. CONCLUSIONS: C. pneumoniae is frequently found in the vessel wall of abdominal aortic aneurysm. The potential etiopathogenetic role of C. pneumoniae in the development of these aneurysms remains to be studied.

Aged↗