Michelle Parker

Characterization of Genetic Diversity of Carbapenem-Resistant Acinetobacter baumannii Clinical Strains Collected from 2004 to 2007

ABSTRACT Genotypes of carbapenem-resistant Acinetobacter baumannii collected by the clinical microbiology laboratory of a university hospital in Chicago, IL, between 2004 and 2007 were analyzed by pulsed-field gel electrophoresis. A single genotype established predominance after being introduced in 2005. Analysis of carbapenemases by PCR revealed that imipenem resistance but not meropenem resistance was associated with the presence of blaOXA-23 and blaOXA-40 genes.

Effects of age and gender on the QT response to exercise

Although gender differences in resting corrected QT intervals have been well documented, the effects of age and exercise on gender differences in QT have not been well characterized. Data were analyzed from 91 healthy volunteers (47 women). Forty-five young subjects (aged 20 to 39 years) and 46 older subjects (61 to 84 years) were recruited. All underwent Bruce protocol stress testing. QT offset and QT peak were measured at exercise stages and during recovery. In a heart rate (HR)-independent analysis, data were divided into HR bins of 10 beats/min. In a HR-dependent analysis, 6 models were used to approximate the QT-RR relation; the best were used to analyze age and gender effects. Women had longer QT intervals than men at a HR < 100 beats/min for QT offset and < 110 beats/min for QT peak. At faster HRs, no significant differences were found. Older subjects had slightly longer QT intervals than the younger group, with a mean difference of 2 ms for QT offset and 9 ms for QT peak. Women had increased constant and slope coefficients. The QT increase in the elderly was relatively small. Gender differences in QT disappear at faster HRs, whereas age differences are smaller but are present throughout exercise, with no significant age-gender interaction. A natural logarithmic model provides the best approximation of the QT-RR relation with exercise, is simple to implement, and should become the preferred method of QT correction.

Reproducibility of Ventricular Fibrillation Characteristics in Patients Undergoing Implantable Cardioverter Defibrillator Implantation

Reproducibility of VF Characteristics. Introduction: The purpose of this study was to evaluate the immediate reproducibility of local electrogram characteristics recorded during repeated episodes of induced ventricular fibrillation (VF) in patients undergoing implantable cardioverter defibrillator (ICD) implantation.

Role of intracoronary ultrasound after high-pressure stent implantation.

BACKGROUND Poststent high-pressure balloon inflation has been shown to improve clinical outcomes. However, it is unknown whether intracoronary ultrasound (ICUS) provides additional clinical guidance after initial high-pressure balloon inflation is used during stent placement. Thus the purpose of this study was to determine if stent deployment techniques are improved with ICUS imaging despite an optimal angiographic result achieved with high-pressure balloon inflation. METHODS AND RESULTS Prospective data were collected on 96 consecutive patients in whom 151 stents were deployed. Stents and high-pressure balloons were angiographically sized 1:1 by visual estimation. High-pressure (> or =12 atm in all cases) balloon inflations were continued until angiographic completion (<10% residual stenosis), after which index ICUS imaging was performed. Stent apposition, symmetry, and lumen dimensions were evaluated. An optimal ICUS result was defined as full apposition of the stent, symmetry ratio > or =0.80, and acute gain > or =0.80 of the reference lumen area. If inadequate ICUS results were found, further dilations with higher pressures or larger balloons and subsequent stent reevaluation with ICUS were performed. Sixty-nine (46%) stents required additional balloon inflations. Of these stents, 35 (23%) had initial acute gains that were <80% of the reference lumen area. Forty-six (30%) stents were found to have unapposed struts and 24 (16%) had a symmetry ratio <0.80. In patients requiring additional inflations, minimum stent area increased from 7.6 +/- 2.2 mm(2) to 9.2 +/- 2.4 mm(2) (P <.0001). Similarly, complete stent apposition improved from 33% to 68% of total stents (P <.0001). After initial ICUS, higher-pressure dilations were performed in 40 patients, whereas larger balloons greater than or equal to ICUS reference vessel diameter were used in 33 patients. Follow-up was obtained in 95 (99%) patients. The overall major adverse cardiac event rate at 6 months was 9.3%, which consisted of 8 target vessel revascularizations and 1 abrupt closure requiring repeat intervention. CONCLUSIONS Even when poststent high-pressure balloon inflation achieves an optimal angiographic result, ICUS assists in optimizing acute gain, symmetry, and apposition of intracoronary stents in approximately 50% of patients. Moreover, ICUS guidance is associated with low rates for target vessel revascularization and major adverse cardiac events at 6-month follow-up.