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Biomedical subjects

Alessandro Parolari

Publications and source records attributed to Alessandro Parolari.

At least 19 recordsLinked to original sources
PubMed2005

Preoperative assessment of the radial artery for coronary artery bypass grafting: is the clinical Allen test adequate?

BACKGROUND: The clinical Allen test (AT) is widely adopted as the only preoperative assessment of the hand collateral circulation before radial artery (RA) harvest as a coronary artery bypass graft. Nevertheless, in some cases it may be misleading because of clinically undetectable anatomic anomalies of the forearm arteries. METHODS: We evaluated the nondominant forearm arterial circulation by echo color Doppler (ECD) technique and by performing static and dynamic tests such as the AT, snuffbox test (SBT), and palmar arch test (PAT) in 150 patients who underwent elective coronary artery revascularization with a RA graft. RESULTS: Although the clinical AT was normal in all patients, in 8 patients (5.3%) preoperative ECD AT, SBT, and PAT did contraindicate RA harvesting. We did not harvest the RA in these patients. In the remaining 142 patients the RA was harvested. We did not observe any case of postoperative forearm or hand ischemia. We examined the blood flow to the hand in all patients at both 5 days and 24 months after surgery. In all patients ECD showed adequate hand perfusion and a significant increase of the peak flow velocity in the ulnar artery at both follow-up times. CONCLUSIONS: The clinical AT may be not sufficient to assess the hand collateral flow and the quality of the RA as a coronary artery bypass graft in at least 5% of patients. The ECD technique, performed during static and dynamic tests, does offer a safer and more objective preoperative noninvasive evaluation and it may have an important role also from the medicolegal point of view.

Blood Flow Velocity↗
PubMed2004

The stimulation of arginine transport by TNFalpha in human endothelial cells depends on NF-kappaB activation.

In human saphenous vein endothelial cells (HSVECs), tumor necrosis factor-alpha (TNFalpha) and bacterial lipopolysaccharide (LPS), but neither interferon gamma (IFNgamma) nor interleukin 1beta (IL-1beta), stimulate arginine transport. The effects of TNFalpha and LPS are due solely to the enhancement of system y+ activity, whereas system y+L is substantially unaffected. TNFalpha causes an increased expression of SLC7A2/CAT-2B gene while SLC7A1/CAT-1 expression is not altered by the cytokine. The suppression of PKC-dependent transduction pathways, obtained with the inhibitor chelerytrhine, the inhibitor peptide of PKCzeta isoform, or chronic exposure to phorbol esters, does not prevent TNFalpha effect on arginine transport. Likewise, ERK, JNK, and p38 MAP kinases are not involved in the cytokine effect, since arginine transport stimulation is unaffected by their specific inhibitors. On the contrary, inhibitors of NF-kappaB pathway hinder the increase in CAT2B mRNA and the stimulation of arginine uptake. These results indicate that in human endothelial cells the activation of NF-kappaB pathway mediates the TNFalpha effects on arginine transport.

Amino Acid Transport Systems, Basic↗
PubMed2004

Upper and lower spinal cord blood supply: the continuity of the anterior spinal artery and the relevance of the lumbar arteries.

OBJECTIVE: Thoracic and thoracoabdominal aortic repair are still complicated by spinal cord ischemia and paraplegia. The aim of the present article is to present the results of an anatomical study conducted by means of both postmortem injection of the vertebral artery and perfusion of the abdominal aorta. METHODS: The spinal cord blood supply was investigated in 51 Caucasian cadavers: in 40 cases a methylene blue solution was hand-injected into the vertebral artery, whereas in the remaining 11 cases the abdominal aorta was perfused with a methylene blue solution by means of a roller pump. The level and side of the arteria radicularis magna and the continuity of the anterior spinal artery were recorded. RESULTS: The anterior spinal artery was a continuous vessel without interruptions along the spinal cord in all 51 cases. The arteria radicularis magna level was variable, ranging from T9 to L5. The arteria radicularis magna arose from a lumbar artery in 36 cases (70.5%) and it was left-sided in 32 cases (62.7%). CONCLUSIONS: The anterior spinal artery constitutes an uninterrupted pathway between the vertebral arteries, the arteria radicularis magna, and the posterior intercostal and lumbar arteries. Moreover, the arteria radicularis magna arises from a lumbar artery in most of cases. Therefore, the sacrifice of the intercostal arteries during a thoracic aorta repair could be justified, at least from an anatomical standpoint. However, if an extended thoracoabdominal aortic repair is planned, it may be prudent to preserve the blood flow from the lumbar arteries.

Aged↗
PubMed2003

Platelet activation induces cell-surface immunoreactive tissue factor expression, which is modulated differently by antiplatelet drugs.

OBJECTIVE: Tissue factor (TF) is the main activator of the coagulation cascade occurring in physiologic and pathologic conditions. Recent data suggest that human platelets might contain TF that is possibly derived from leukocytes. In this study, we investigated whether intraplatelet TF can be exposed on the membrane by platelet agonists. The modulation of this process by antiplatelet drugs has been evaluated as well. METHODS AND RESULTS: Flow cytometric analysis of unstimulated platelets showed a small amount of membrane-associated immunoreactive TF (irTF) in whole blood, platelet-rich plasma, and washed platelets isolated from healthy subjects. ADP, thrombin receptor-activating peptide, and epinephrine significantly increased functionally active, membrane-associated irTF. ADP induced irTF exposure in a concentration- and time-dependent fashion. Agonist-induced irTF expression was completely inhibited by iloprost but not by aspirin. Interestingly, glycoprotein IIb/IIIa antagonists did not inhibit but rather potentiated the stimulatory effect of ADP on platelet irTF expression. Real-time polymerase chain reaction experiments showed detectable amounts of TF mRNA in unstimulated platelets. CONCLUSIONS: These findings indicate that platelet agonists and antiplatelet drugs might modulate platelet-associated irTF expression. Regulated TF expression establishes the potential for a previously unrecognized role for platelets in sustaining thrombus formation and growth via coagulation-mediated mechanisms.

Antigens, Surface↗
PubMed2003

Long-term outcome after inflammatory abdominal aortic aneurysm repair: case-matched study.

The purpose of this study was to compare early and late outcomes after inflammatory and noninflammatory abdominal aortic aneurysm (AAA) repair with emphasis on graft-related complications. Of 625 consecutive patients submitted to AAA repair, 18 were classified as having inflammatory AAAs (group 1). The results of this group were compared with those of 54 patients (group 2) retrospectively drawn from patients who underwent aortic replacement for noninflammatory AAAs. A computer-assisted matching system was used to match patients according to date of birth, gender, and surgical priority. All patients of both groups were followed by periodic clinical and instrumental examinations. Patients in group 1 complained more frequently of aneurysm-related symptoms (72% vs. 20%; p = 0.0001), and their erythrocyte sedimentation rate was elevated more often (78% vs. 19%; p < 0.0001). Surgical morbidity and mortality rates were not different. The mean lengths of follow-up were 61 +/- 47 months (group 1) and 71 +/- 38 months (group 2). The 10-year overall survival rates did not differ significantly between the two groups (49.1% +/- 16.9% for group 1 vs. 61.6% +/- 13.8% for group 2; p = 0.26, log-rank test). In contrast, the free from paraanastomotic aneurysm survival rates were significantly lower in group 1 (57.3% +/- 20.2% vs. 97.8% +/- 2.5% at 10 years; p = 0.025, log-rank test). Long-term outcomes showed a higher incidence of graft-related complications in group 1. As inflammatory aneurysms might represent a risk factor for the development of paraanastomotic aneurysms, routine imaging surveillance of graft aortic healing after inflammatory AAA repair is warranted.

Aged↗
PubMed2003

Off-pump versus on-pump coronary artery bypass: meta-analysis of currently available randomized trials.

BACKGROUND: Off-pump coronary artery bypass (OPCAB) challenges the conventional on-pump coronary artery bypass grafting (CABG) as the standard of surgical therapy for coronary disease. The aim of this study is to assess the differences in clinical outcomes between CABG and OPCAB by meta-analysis of data published in randomized trials. METHODS: A literature search (Medline, Pubmed, Cochrane Controlled Trials Register, and the Cochrane Medical Editors Trial Amnesty of unpublished clinical trials) was done for the period starting from January 1990 until May 2002 and was supplemented with a manual bibliographic review for all peer-reviewed English language publications. A systematic overview (meta-analysis) of the randomized trials was done to define the risk of the composite end point (death, stroke, or myocardial infarction) in CABG versus OPCAB. RESULTS: A literature search yielded nine comparable randomized studies, for a total of 1090 patients, of whom 558 and 532 were randomly assigned to CABG and OPCAB, respectively. Meta-analysis of these studies showed a trend, albeit not statistically significant, toward reduction in the risk of the composite end point for patients who had OPCAB (odds ratio 0.48; 95% confidence interval 0.21 to 1.09; p = 0.08). CONCLUSIONS: Cumulative analysis of the few prospective randomized studies currently available found a potential clinical benefit of OPCAB, indicating that the avoidance of extracorporeal circulation might result in improved clinical outcomes. Further evidence, however, from large randomized trials is needed to assess potential advantages of OPCAB in terms of early outcomes.

Aged↗
PubMed2003

Oxygen metabolism during and after cardiac surgery: role of CPB.

BACKGROUND: Cardiopulmonary bypass (CPB) has been reported to increase oxygen metabolism and to influence the relation between oxygen consumption (VO(2)) and delivery (DO(2)) in the early hours after cardiac surgery. To investigate the role of CPB, we studied oxygen metabolism in coronary artery bypass procedures performed on-pump (CABG) and off-pump (OPCAB). METHODS: Twenty-five patients were randomized to undergo CABG (n = 14) or OPCAB (n = 11). All patients received the same anesthetic management. Oxygen metabolism variables were assessed before induction of anesthesia and up to 18-hours after surgery. RESULTS: At baseline, before induction of anesthesia, there were no differences between CABG and OPCAB in oxygen consumption (VO(2)), delivery (DO(2)), or extraction (ExO(2)). After surgery VO(2) and ExO(2) increased in both groups, while DO(2) decreased. No significant differences between CABG and OPCAB were detected in postoperative VO(2), DO(2), and ExO(2) levels. The relation between VO(2) and DO(2) was very similar in CABG and OPCAB patients throughout the study, and no significant differences were detected in slopes and intercepts of the regression lines between CABG and OPCAB at all time points. There was, however, a significant effect of time on the relation between VO(2) and DO(2): this relation was stronger in the postoperative period, and the slope of this relation increased over time as well. CONCLUSIONS: A hypermetabolic state and progressive and significant increases in the strength of the relationship between VO(2) and DO(2) and in the slope of this relationship occur after both CABG and OPCAB. Cardiopulmonary bypass is not responsible for these changes in oxygen metabolism.

Cardiopulmonary Bypass↗
PubMed2003

Statins in coronary bypass surgery: rationale and clinical use.

Statin therapy prevents the first occurrence and recurrence of coronary events and reduces cardiovascular and general mortality in patients with coronary artery disease. These compounds modulate a variety of processes involved in the pathophysiology of arteriosclerosis and vascular graft disease by lipid-dependent and lipid-independent (pleiotropic) mechanisms. As a result, statins produce angiographic and clinical benefits in patients undergoing coronary bypass surgery. We review the present knowledge about the effects of statins on this pathologic condition and the evidence supporting an early treatment initiation.

Arteriosclerosis↗
PubMed2003

Biological effects of off-pump vs. on-pump coronary artery surgery: focus on inflammation, hemostasis and oxidative stress.

Cardiopulmonary bypass (CPB) has been recognized as a cause of complex systemic inflammatory response, which significantly contributes to several adverse postoperative complications. In the last few years, off-pump coronary artery bypass grafting has gained widespread diffusion as an alternative technique to conventional on-pump coronary artery bypass grafting. Surgeons supporting off-pump surgery state that the avoidance of the CPB and myocardial ischemia-reperfusion significantly reduces the postoperative systemic inflammatory response and other biological derangements and, possibly, may improve the clinical outcomes. We review, here, the available evidence concerning possible differences between off-pump and on-pump procedures in terms of inflammation, hemostasis and oxidative stress. Consistent differences in the involvement of these systems are observed, but they are limited to the final steps of the surgical procedures and the early hours after. These findings suggest that the global surgical trauma may be as important, or even more, as the CPB in terms of systemic inflammatory and coagulation-fibrinolytic pathway activation. Further studies are needed in order to confirm this hypothesis.

Biomarkers↗
PubMed2003

Coagulation and fibrinolytic markers in a two-month follow-up of coronary bypass surgery.

OBJECTIVES: The alterations of the coagulation-fibrinolytic profile immediately and up to few days after cardiac surgery have been widely documented. However, less information is available on whether these alterations persist for prolonged periods of time after the operation. In this study we have evaluated the coagulation-fibrinolytic profile of patients who underwent coronary artery surgery with cardiopulmonary bypass during a 2-month follow-up period. METHODS: Twenty-six patients (age range, 50-75 years) were studied. Blood samples were collected before the intervention and at different time points postoperatively up to 2 months after the operation. Measurement of selected coagulation-fibrinolytic variables was carried out in plasma from 16 patients. Evaluation of tissue factor activity determined as procoagulant activity was performed in peripheral blood mononuclear leukocytes obtained from 10 patients. RESULTS: Antigenic levels of clottable fibrinogen, prothrombin fragment F1.2, D-dimer, and thrombin-antithrombin complex were significantly increased during the first week after the intervention compared with preoperative values. Prothrombin fragment F1.2 levels returned to normal within 15 days, fibrinogen levels normalized within 30 days, and thrombin-antithrombin complex levels normalized at 45 days, whereas D-dimer values were still significantly higher 60 days postoperatively respective to baseline values. There was a trend toward an increased procoagulant activity from peripheral blood mononuclear leukocytes 4 days after the operation, whereas no changes of factor VII measured either as antigen or in its coagulant and activated forms were recorded throughout the study. CONCLUSIONS: A marked activation of the coagulation-fibrinolytic system occurs after cardiopulmonary bypass and lasts for at least 2 months thereafter. This finding suggests that these alterations might account for the increased thrombotic risk of these patients during the postoperative period.

Aged↗
PubMed2002

Lack of association between serum immunoreactivity and Chlamydia pneumoniae detection in the human aortic wall.

BACKGROUND: Only a few studies have focused the attention on the relation between elevated anti-Chlamydia pneumoniae (CP) antibodies and the detection of CP in the arterial wall. The aim of our study is thus to investigate the relationship between immune response to CP and detection of CP in the aortic walls of patients with abdominal aortic aneurysm. METHODS AND RESULTS: A specimen of aortic wall was obtained from 102 consecutive patients who underwent abdominal aneurysm repair. The possible presence of CP was studied by polymerase chain reaction and confirmed by nonradioactive DNA hybridization. Antibody response to CP was studied (IgG, IgA titers). We found 33 patients (32.4%) with CP DNA+. No correlation between CP DNA detection and antibody titers was found (IgG P=0.52, IgA P=0.66). High correlation between IgG and IgA titer was observed (P<0.01). Endovascular presence of CP and antibody titers was not related to the age of the patient. CONCLUSIONS: CP antibody titers are not associated with the presence of CP in the aortic wall of patients with abdominal aortic aneurysm.

Antibodies, Bacterial↗
PubMed2002

Endothelial damage during myocardial preservation and storage.

Preservation and storage techniques represent two major issues in routine cardiac surgery and heart transplantation. Historically, these methods were conceived to prevent ischemic injury to myocardium after cardiac arrest during heart operations. Evidence shows that endothelium plays a critical role in the maintenance of normal heart function after cardiac operation, mainly by controlling the coronary circulation. Methods for preservation and storage, developed initially to protect cardiomyocyte function, may be deleterious for vascular endothelium and compromise myocardial protection. In this review article the present knowledge about endothelial injury secondary to preservation and storage techniques is discussed.

Cardioplegic Solutions↗
PubMed2002

Endothelial cell injury induced by preservation solutions: a confocal microscopy study.

BACKGROUND: We evaluated the effects of standard preservation solutions on cultured human greater saphenous vein endothelial cells. METHODS: Endothelial cells (eight strains) were preincubated for 6 or 24 hours at 4 degrees C in Celsior, Euro-Collins, St. Thomas Hospital II, and University of Wisconsin solutions, reincubated in warm oxygenated culture medium 199, and observed up to 48 hours. Culture viability was assessed through cell counting and confocal microscopy of calcein loaded cells. RESULTS: Incubation in both Euro-Collins and St. Thomas, but not in Celsior or University of Wisconsin solutions, caused significant cells losses and diffuse morphological damages characterized by solution-specific distinctive alterations. Injury caused by 6-hour, but not by 24-hour treatment, was reversible. CONCLUSIONS: The incubation with Celsior and University of Wisconsin solutions substantially preserved endothelial viability and proliferative capability. Conversely, a prolonged incubation in either Euro-Collins or St. Thomas solutions caused severe and potentially irreversible damage referable to the induction of, respectively, apoptotic or necrotic changes.

Aged↗
PubMed2002

Acute effects of 17beta-estradiol on left internal mammary graft after coronary artery bypass grafting.

BACKGROUND: Vasospasm of arterial conduits used for coronary surgical procedures is an important cause of postoperative graft failure. Mounting experimental evidence suggests that estrogen reverses acetylcholine-induced vasospasm of the coronary arteries in animals and humans. Estrogen also affects endothelium-derived constrictor factors. We therefore investigated the in vivo vasomotor responses to transdermal 17beta-estradiol of the left internal mammary artery (LIMA) grafted on the anterior descending coronary artery. METHODS: We studied 20 women, mean age of 62 +/- 7.2 years (range, 48 to 73 years), who had undergone cardiopulmonary bypass for coronary artery bypass grafting. They received transdermal 17beta-estradiol on the fifth day after operation. The diameter, cross-sectional area, and blood flow of the LIMA graft were measured by transthoracic color Doppler echography before (basal values) and after the transdermal administration of 50 microg of 17beta-estradiol (control). RESULTS: LIMA graft vasodilation after the administration of 17beta-estradiol was observed. A significant increase in diameter (2.06 +/- 0.4 mm versus 2.37 +/- 0.28 mm; p = 0.035) and cross-sectional area (3.45 +/- 1. 2 mm2 versus 4.24 +/- 1 mm2; p = 0.039) was registered. The LIMA graft mean flow increased by 49% (44.76 +/- 27.19 mL/min versus 56.62 +/- 27.69 mL/min), but this increase was not statistically significant (p = 0.06). CONCLUSIONS: The acute postoperative transdermal administration of 17beta-estradiol induced a significant increase of LIMA graft diameter and cross-sectional area in postmenopausal women who underwent coronary artery bypass grafting. The LIMA graft vasodilation was also associated with an improvement in LIMA blood flow.

Administration, Cutaneous↗