Coronary endothelial dysfunction in patients with acute-onset idiopathic dilated cardiomyopathy

AbstractObjectives. This study sought to determine whether coronary endothelial dysfunction exists in patients with acute-onset idiopathic dilated cardiomyopathy (DCM) and to explore its relation to recovery of left ventricular systolic function in this patient population.Background. Coronary endothelial dysfunction exists in chronic DCM, but its importance in the development and progression of ventricular dysfunction is not known. To address this issue we studied coronary endothelial function in patients with idiopathic DCM <6 months in duration and explored the relation between coronary endothelial function and subsequent changes in left ventricular ejection fraction (LVEF).Methods. Ten patients with acute-onset idiopathic DCM (duration of heart failure symptoms 2.0 ± 0.4 months [mean ± SEM]) and 11 control patients with normal left ventricular function underwent assessment of coronary endothelial function during intracoronary administration of the endothelium-dependent vasodilator acetylcholine and the endothelium-independent vasodilator adenosine. Coronary cross-sectional area (CSA) was determined by quantitative coronary angiography and coronary blood flow (CBF) by the product of coronary CSA and CBF velocity measured by an intracoronary Doppler catheter. Patients with DCM underwent assessment of left ventricular function before and several months after the study.Results. Acetylcholine infusion produced no change in coronary CSA in control patients but significant epicardial constriction in patients with DCM (−36 ± 11%, p < 0.01). These changes were associated with increases in CBF in control patients (+118 ± 49%, p < 0.01) but no change in patients with DCM. Infusion of adenosine produced increases in coronary caliber and blood flow in both groups. Follow-up assessment of left ventricular function was obtained in nine patients with DCM 7.0 ± 1.7 months after initial study, at which time LVEF had improved by ≥0.10 in four patients. Multiple linear regression revealed a positive correlation between both the coronary CSA (r2 = 0.57, p < 0.05) and CBF (r2 = 0.68, p < 0.01) response to acetylcholine and the subsequent improvement in LVEF.Conclusions. Coronary endothelial dysfunction exists at both the microvascular and the epicardial level in patients with acute-onset idiopathic DCM. The preservation of coronary endothelial function in this population is associated with subsequent improvement in left ventricular function

Myogenic influences on the electrical auditory brainstem response (EABR) in humans

Two cases demonstrating the effects of myogenic artifact on the electrical auditory brainstem response (EABR) when using a promontory stimulation site are presented. Intensity‐response functions were obtained in the unparalyzed condition, then repeated after infusion of a neuromuscular paralyzing agent. In both cases, the myogenic response was observed at lower stimulus intensities than the EABR components. As intensity increased, the myogenic responses grew at extremely rapid rates and made any subsequent identification of auditory responses virtually impossible. To alleviate the adverse influence of myogenic components, general anesthesia and a paralyzing agent must be incorporated into the test protocol when acquiring the EABR using a promontory site of stimulation

Differences Among Cardiologists in Rates of Positive Coronary Angiograms

Background: Understanding the sources of variation for high‐cost services has the potential to improve both patient outcomes and value in health care delivery. Nationally, the overall diagnostic yield of coronary angiography is relatively low, suggesting overutilization. Understanding how individual cardiologists request catheterization may suggest opportunities for improving quality and value. We aimed to assess and explain variation in positive angiograms among referring cardiologists. Methods and Results: We identified all cases of diagnostic coronary angiography at Massachusetts General Hospital from January 1, 2012, to June 30, 2013. We excluded angiograms for acute coronary syndrome. For each angiogram, we identified clinical features of the patients and characteristics of the requesting cardiologists. We also identified angiogram positivity, defined as at least 1 epicardial coronary stenosis ≥50% luminal narrowing. We then constructed a series of mixed‐effects logistic regression models to analyze predictors of positive coronary angiograms. We assessed variation by physician in the models with median odds ratios. Over this time period, 5015 angiograms were identified. We excluded angiograms ordered by cardiologists requesting <10 angiograms. Among the remaining 2925 angiograms, 1450 (49.6%) were positive. Significant predictors of positive angiograms included age, male patients, and peripheral arterial disease. After adjustment for clinical variables only, the median odds ratio was 1.23 (95% CI 1.0–1.36), consistent with only borderline clinical variation after adjustment. In the full clinical and nonclinical model, the median odds ratio was 1.07 (95% CI 1.07–1.20), also consistent with clinically insignificant variation. Conclusions: Substantial variation exists among requesting cardiologists with respect to positive and negative coronary angiograms. After adjustment for clinical variables, there was only borderline clinically significant variation. These results emphasize the importance of risk adjustment in reporting related to quality and value

Ototoxicity in cystic fibrosis patients receiving intravenous tobramycin for acute pulmonary exacerbation: Ototoxicity following tobramycin treatment

Aminoglycosides are commonly used to treat infections in CF patients and are highly ototoxic. The incidence of tobramycin-induced hearing loss, tinnitus, vertigo or dizziness (ototoxicity) varies widely from 0 to 56% secondary to variation in patient enrollment, dosing, audiometry, and ototoxic criteria. The aim of this study is to determine the incidence of ototoxicity after one course of once-daily IV tobramycin in CF patients. Adult CF patients with acute pulmonary exacerbations were enrolled on IV tobramycin (10 mg/kg/d, ≥10 days). Pure-tone audiometry was performed for standard and extended high frequencies in the sensitive range for ototoxicity (SRO). American-Speech-Language-Hearing-Association cochleotoxicity criteria were applied. Distortion product otoacoustic emissions (DPOAE) and the words-in-noise-test (WINT) were assessed. Tinnitus Functional Index (TFI) and Vertigo Symptoms Scale (VSS) were used. Eighteen CF patients, mean age 31.1 (18-59), were enrolled. The incidence of cochleotoxic change from baseline at 2 and 4 weeks post-treatment was 89% and 93%. For DPOAE, a measure of outer hair-cell function, the incidence of ≥5 dB decrease was 82% and 80%. For WINT, a measure of word recognition, the incidence of ≥10% decrease was 17% and 40%. For TFI, the incidence of ≥10pt increase was 12% and 8%, and for VSS, the incidence of ≥6pt increase was 0% and 8%. One course of IV tobramycin was sufficient to cause hearing loss and other ototoxic symptoms four weeks after treatment ended. Audiometric measures were more sensitive to ototoxic change than TFI & VSS. Age and duration of tobramycin treatment were not obvious factors for predicting ototoxicity

“Thence to the River Plate”: steamship mobilities in the South Atlantic, 1842-1869

This article engages theories of mobility to examine the Royal Mail Steam Packet Company’s 1851 expansion into South America. Through a focus on cooperative strategies and trans-oceanic connections, the article also considers the interplay between Atlantic and wider world shipping networks. The first part of the paper compares the Royal Mail Steam Packet Company’s (RMSPC’s) South American branch to the more established West Indies route, and probes the significance of the Company’s expansion into the South Atlantic in light of the RMSPC’s perceived national and imperial role. The second part of the paper turns to the RMSPC’s cooperative strategies and connections between the Atlantic and the Pacific oceans. Considered as a case study, the RMSPC indicates that the boundaries of British imperial influence incorporated a degree of flexibility during this period, pointing to a need to revise rigid conceptualisations of empire. An argument is also made for the continuing relevance of the Atlantic as a spatial unit during this era, despite the increasingly global connections of the nineteenth-century world