Relative importance of patient, procedural and anatomic risk factors for early vein graft thrombosis after coronary artery bypass graft surgery.

AIM: The aim of the present study was to investigate the relative importance of a wide array of patient demographic, procedural, anatomic and perioperative variables as potential risk factors for early saphenous vein graft (SVG) thrombosis after coronary artery bypass graft (CABG) surgery. METHODS: The patency of 611 SVGs in 291 patients operated on at four different hospitals enrolled in the Reduction in Graft Occlusion Rates (RIGOR) study was assessed six months after CABG surgery by multidetector computed tomography coronary angiography or clinically-indicated coronary angiography. The odds of graft occlusion versus patency were analyzed using multilevel multivariate logistic regression with clustering on patient. RESULTS: SVG failure within six months of CABG surgery was predominantly an all-or-none phenomenon with 126 (20.1%) SVGs totally occluded, 485 (77.3%) widely patent and only 16 (2.5%) containing high-grade stenoses. Target vessel diameter ≤ 1.5 mm (adjusted OR 2.37, P=0.003) and female gender (adjusted OR 2.46, P=0.01) were strongly associated with early SVG occlusion. In a subgroup analysis of 354 SVGs in which intraoperative graft blood flow was measured, lower mean flow was also significantly associated with SVG occlusion when analyzed as a continuous variable (adjusted OR 0.984, P=0.006) though not when analyzed dichotomously, <40 mL/min versus ≥ 40 mL/min (adjusted OR 1.86, P=0.08). CONCLUSION: Small target vessel diameter, female gender and low mean graft blood flow are significant risk factors for SVG thrombosis within six months of CABG surgery in patients on postoperative aspirin therapy. This information may be useful in guiding revascularization strategies in selected patients.

Effect of anti-platelet factor-4/heparin antibody induction on early saphenous vein graft occlusion after coronary artery bypass surgery.

BACKGROUND: Antibodies to complexes of heparin and platelet factor 4 (PF4) are capable of causing heparin-induced thrombocytopenia (HIT). Recent evidence suggests that anti-PF4/heparin antibodies may be prothrombogenic even in the absence of thrombocytopenia and clinically-recognized HIT. OBJECTIVES: To determine if induction of anti-PF4/heparin antibodies is an independent risk factor for early saphenous vein graft (SVG) occlusion or adverse clinical outcome after coronary artery bypass graft (CABG) surgery. PATIENTS/METHODS: Anti-PF4/heparin antibody titers were measured in 368 patients prior to and then 4 days, 6 weeks and 6 months after CABG surgery. Serotonin release assay (SRA) and antibody isotype analysis were also performed on 6-week samples. SVG patency was determined in 297 patients 6 months after surgery by multidetector computed tomography coronary angiography. RESULTS: Six weeks after surgery, 52% of patients were anti-PF4/heparin seropositive and 9% were SRA positive. Six months after surgery, neither the percentage of occluded SVG (19% vs. 20%, P = NS), the percentage of patients with an occluded SVG (33% vs. 33%, P = NS) nor the incidence of adverse clinical events (21% vs. 24%, P = NS) differed between seropositive and seronegative groups. Neither IgG isotype nor SRA positivity was additionally predictive of SVG occlusion or adverse clinical outcome. CONCLUSION: Induction of anti-PF4/heparin antibodies, even those capable of heparin-dependent platelet activation, is not independently associated with early SVG occlusion or adverse clinical outcomes after CABG surgery.

Management of respiratory failure in patients with asthma.

The goal of management of patients with respiratory failure is to restore them to a state of quiet breathing, without complication. This goal is often achieved by pharmacotherapy alone. Inhaled albuterol sulfate, oxygen, and systemic corticosteroids are mainstays of acute care drug management, whereas other data support the use of inhaled steroids, ipratropium bromide, magnesium sulfate, theophylline, and heliox. Assisted ventilation by face mask or endotracheal tube may be required in refractory patients. In intubated patients, a ventilatory strategy that prolongs exhalation time and accepts hypercapnia minimizes lung hyperinflation and generally results in a good outcome. Acute asthma often represents failure of outpatient management; key aspects of the outpatient program should be addressed in the acute care setting to help prevent recurrent attacks.

Middle cerebral artery occlusion after pterional approach to basilar bifurcation aneurysm: technical case report.

OBJECTIVE AND IMPORTANCE: The authors present a case of a subacute middle cerebral artery occlusion that was sustained subsequent to a basilar apex aneurysm clipping via the pterional approach. A middle cerebral artery stroke is a rare complication of basilar bifurcation aneurysm clipping, and, to our knowledge, this complication has not been previously described in otherwise healthy patients with unruptured basilar aneurysms. CLINICAL PRESENTATION: A 36-year-old woman was found to have an unruptured 1.6 x 1.0-cm basilar tip aneurysm, as revealed by computed tomography. She elected to undergo surgical repair. TECHNIQUE: Transsylvian dissection, exposure, and uneventful clipping of the basilar bifurcation aneurysm were performed. CONCLUSIONS: A middle cerebral artery stroke occurring after the repair of an intact basilar aneurysm has several possible causes, including retraction injury and direct surgical injury. Awareness of this complication is important for the early recognition and management of the occlusion before infarction is established.

Postneurulation rapid brain growth represents a critical time for encephalocele formation: a chick model.

Current theory regarding the pathogenesis of encephaloceles suggests that the defect occurs after neurulation is completed in which brain tissue herniates through defective mesodermal elements necessary for skull modeling. To better delineate the mechanisms of encephalocele development, we performed a variety of microsurgical manipulations in the developing cranium of the chick embryo during the postneurulation period of early rapid brain growth. The results of the study revealed that encephaloceles could be induced in 78% of chick embryos manipulated at stage 26 that had evidence of marked decompression of the primitive ventricle. On the other hand, control embryos or embryos manipulated without ventricular decompression at stage 26 did not develop encephaloceles (0 of 32). Embryos with decompression of the primitive ventricle treated at earlier stages (20-24) showed only a 5% incidence of encephaloceles. These findings suggest that there is both a critical time point during postneurulation rapid brain growth when encephaloceles are prone to occur and a mesenchymal defect associated with decompression of the primitive ventricle that must be present to induce encephaloceles.

Recombination between repeats in Escherichia coli by a recA-independent, proximity-sensitive mechanism.

We have examined the influence of proximity on the efficiency of recombination between repeated DNA sequences in Escherichia coli. Our experiments have employed a plasmid-based assay to detect deletions between direct repeats of 100 bp. The rate of deletion of the juxtaposed direct repeats was reasonably high at 6 x 10(-5) per cell. A comparison of recA+ and recA mutant strains showed that these deletion events are primarily the result of recA-independent recombination at these homologous sequences. Random restriction fragments of yeast or E. coli genomic DNA were used to separate the two repeats. Deletion rates decreased over two orders of magnitude with increasing separation of up to 7 kb. There was a surprisingly strong effect of even short sequence separations, with insertions of a few hundred base pairs exhibiting 10-fold reductions of deletion rates. No effect of recA on the efficiency of deletion was observed at any distance between repeats.