Incidence and predictors of eosinophilic myocardial hypersensitivity in patients receiving home dobutamine

Background

Home inotropes are utilised in those with end-stage heart failure as a bridge to cardiac transplantation. The use of intravenous dobutamine has been linked to cases of eosinophilic myocardial hypersensitivity (EMH), however, little is known about incidence and predictors.

Purpose

We sought to examine the incidence and possible predictors of eosinophilic myocardial hypersensitivity in a cohort of patients on home inotrope therapy at a cardiac transplant centre.

Methods

Patients enrolled in the home inotrope program with progression to heart transplantation or ventricular assist device (VAD) with available myocardial tissue for histopathology, from January 2000 to May 2020 were included. EMH was defined by a pathologist reporting eosinophilic infiltrate with hypersensitivity on myocardial histopathology.

Results

From a cohort of 74 patients, 58% (43) were on dobutamine and 42% (31) were on milrinone. There were zero cases of EMH in those on milrinone. EMH was identified in 14% (6/43) of patients receiving dobutamine. In the dobutamine cohort, the mean age was 52-±12 years, with 22% being female. Non-ischaemic dilated cardiomyopathy encompassed 62%, the remaining 38% were ischaemic cardiomyopathy. Median dobutamine dose (250 [200–282] mcg/min vs. 225 [200–291] mcg/min) and duration of therapy (41 [23–79] days vs. 53 [24–91] days) were similar between those with and without EMH. Rates of known allergy (27% vs. 33%) and asthma (1 patient in each group) were also similar between those with and without EMH. Those with EMH had a median peak eosinophil count of 0.40×109/L (IQR 0.21–0.66×109/L) compared to a peak of only 0.10×109/L (IQR 0.06–0.29×109/L) in the non-EMH cohort. There was a significant difference in the change in absolute eosinophil count between groups; over the duration of dobutamine therapy the median change in eosinophil count was 0.31×109/L (IQR 0.21–0.59×109/L) in the EMH group compared to 0.03×109/L (IQR 0.00–0.14×109/L) in the non-EMH cohort (p=0.02). Peak C-reactive protein was similar between groups (42±46mg/L vs. 44±45mg/L). Mean left ventricular ejection fraction (LVEF) reduced from 19% (±7%) to 17% (±2%) in those with EMH, while LVEF increased from 20% (±7%) to 22% (±9%) in non-EMH patients (Figure 1), p=NS. Re-presentation with heart failure requiring hospitalisation occurred in 83% in the EMH group compared to only 59% in the non-EMH group (p=0.26). The majority of patients with EMH (83%) required VAD as bridge to transplant, compared to only 41% of non-EMH (p=0.05).

Conclusion(s)

EMH occurred in 14% of patients receiving home dobutamine. Patients who developed EMH were more likely to require escalation in treatment to VAD as a bridge to heart transplant. In patients receiving dobutamine a reduction in LVEF, hospitalisation with decompensated heart failure and rising eosinophil count should prompt physicians to consider EMH.

Funding Acknowledgement

Type of funding sources: None. Figure 1

Perspective: APOBEC mutagenesis in drug resistance and immune escape in HIV and cancer evolution

The apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like (APOBEC) mutational signature has only recently been detected in a multitude of cancers through next-generation sequencing. In contrast, APOBEC has been a focus of virology research for over a decade. Many lessons learnt regarding APOBEC within virology are likely to be applicable to cancer. In this review, we explore the parallels between the role of APOBEC enzymes in HIV and cancer evolution. We discuss data supporting the role of APOBEC mutagenesis in creating HIV genome heterogeneity, drug resistance, and immune escape variants. We hypothesize similar functions of APOBEC will also hold true in cancer.

The bioequivalence of a single intravenous administration of the anesthetic alfaxalone in cyclodextrin versus alfaxalone in cyclodextrin plus preservatives in cats

To demonstrate the bioequivalence of alfaxalone in cyclodextrin (Reference Product) to a formulation of alfaxalone in cyclodextrin also containing the preservatives ethanol, chlorocresol, and benzethonium chloride (Test Product) when administered for the purpose of inducing anesthesia in the cat. Blinded, single-dose, randomized, two-period, two-sequence, cross-over bioequivalence study with a 7-day washout period between treatments. Twenty-four (12 neutered males and 12 intact females), healthy, adult cats weighing 4.1±0.9 kg. Cats were administered 5 mg/kg IV of alfaxalone in the Reference or Test Product using a randomized cross-over design. One-milliliter venous blood samples were collected at predetermined time points to 12 hr after drug administration to determine alfaxalone plasma concentration over time. Alfaxalone concentrations were determined by a validated analytical testing method using HPLC-MS/MS. Plasma profiles of alfaxalone concentration against time were analyzed by noncompartmental analysis. The pivotal variables for bioequivalence were AUC_last and C_max . Equivalence was achieved if the 90% confidence interval for AUC_last and C_max fell into the asymmetric ±20% interval (0.80-1.25). Physiological variables, quality of anesthesia visual analog scale (VAS) scoring and anesthetic event times were recorded. ANOVA or ANCOVA (single time point), RMANOVA or RMANCOVA (multiple time point) was used for normally distributed data. GLIMMIX was used for nonnormally distributed data. VAS scores were analyzed as for blood bioequivalence data. Variables were evaluated for safety and assessed at alpha = 0.10. C_max and AUC_last for Reference and Test Products were statistically bioequivalent. No physiological variables except for a drug by time interaction for respiratory rate differed between treatment groups, and this difference was not clinically relevant. No anesthetic event times or VAS scores for quality of anesthesia were different between treatment groups. Neither formulation caused pain upon injection. The Reference and Test Products are pharmaceutically bioequivalent formulations when administered as a single intravenous administration for the purpose of induction of anesthesia in cats.

Deferoxamine-fibrin accelerates angiogenesis in a rabbit model of peripheral ischemia

The intramuscular (IM) injection of a modified fibrin meshwork plus deferoxamine was tested in a rabbit model of acute hind-limb ischemia. After excision of the left external iliac and femoral arteries, 12 rabbits at the Milwaukee Heart Institute were divided into two groups: control and fibrin meshwork plus deferoxamine (FDEF) IM. The rabbits underwent angiography before surgery, immediately after, and 1 month postoperatively. These data were compiled through counting by means of a grid overlay. Another 12 rabbits at the Vakhidov Center of Surgery, which did not undergo angiography, underwent lower limb-calf blood pressure (LCBP) measurements made immediately after surgery and at postoperative days 10, 20 and 30. Biopsies from thigh skeletal muscles of rabbits that had L-CBP measurements underwent alkaline phosphatase staining on day 30 to determine the percentage of biopsied area that was occupied by capillaries. The number of arteries and arterioles crossing 71 grid intersections immediately post-surgery decreased from 30.2 6 2.3 to 18.0 6 2.0 (p, 0.05). One month post-surgery this number increased to 29.2 6 2.4 in controls (p, 0.05 vs immediately post-surgery) and to 59.6 6 3.2 in the FDEF group (p, 0.001 vs immediately post-surgery). By day 30 the L-CBP ratio improved in the FDEF group (0.8 6 0.02) vs controls (0.3 6 0.04). By day 30 the capillary density increased from that of normal muscle tissue (198.6 6 12.9/mm2) to 292 612.4/mm2 in the FDEF group (p, 0.05), but decreased in the control group to 98.7 6 7.7/mm2. IM injection of FDEF considerably accelerated angiogenesis in severely ischemic hind-limb tissue in this model, making it a viable treatment method for clinical use in patients who have critical limb ischemia.

Induction of heart failure: haemodynamic comparison of three different canine models

We compared three methods: arteriovenous anastomosis, doxorubicin administration, and combination of anastomosis and doxorubicin, with the intention of designing a simple, stable model of chronic heart failure. Twelve dogs were divided into three groups of four. One group received carotid-jugular anastomosis (Ana series), another group received anastomosis and doxorubicin injection (A/D series), and the last group received only doxorubicin (Dox series). Animals were followed for eight weeks. Fifteen different haemodynamic parameters were tracked and compared to baseline values. After eight weeks, diastolic pressure in the right atrium increased from 3.8±2.0 mmHg at baseline to 5.3±5.9 mmHg in the Ana series, to 6.3±3.3 mmHg in the Dox series and to 8.0±2.0 mmHg in the A/D series ( P<0.05 A/D vs. baseline). Systolic pulmonary wedge pressure increased from 11.6±2.0 mmHg at baseline to 15.5±3.4 mmHg in the Ana series, 14.0±3.7 mmHg in the Dox series and 17.3±4.2 mmHg in the A/D series ( P = NS vs. baseline). Left ventricular ejection fraction decreased from 53.9±10% at baseline to 36.1±5.6% in the Ana series ( P<0.05 vs. baseline), 31.5±5.4% in the Dox series ( P<0.05 vs. baseline) and 25.8±5.8% in the A/D series ( P<0.001 vs. baseline, P<0.05 vs. Ana series and Dox series). In conclusion, eight weeks are not enough to produce stable heart failure using arteriovenous anastomosis alone. Doxorubicin administration alone produces a left ventricular failure. However, a combination of both of these interventions provides a more stable model of right-and left-sided heart failure

Clinical and post mortem analysis of combat neck injury used to inform a novel coverage of armour tool

INTRODUCTION

There is a requirement in the Ministry of Defence for an objective method of comparing the area of coverage of different body armour designs for future applications. Existing comparisons derived from surface wound mapping are limited in that they can only demonstrate the skin entry wound location. The Coverage of Armour Tool (COAT) is a novel three-dimensional model capable of comparing the coverage provided by body armour designs, but limited information exists as to which anatomical structures require inclusion. The aim of this study was to assess the utility of COAT, in the assessment of neck protection, using clinically relevant injury data.

METHOD

Hospital notes and post mortem records of all UK soldiers injured by an explosive fragment to the neck between 01 Jan 2006 and 31 December 2012 from Iraq and Afghanistan were analysed to determine which anatomical structures were responsible for death or functional disability at one year post injury. Using COAT a comparison of three ballistic neck collar designs was undertaken with reference to the percentage of these anatomical structures left exposed.

RESULTS

13/81 (16%) survivors demonstrated complications at one year, most commonly upper limb weakness from brachial plexus injury or a weak voice from laryngeal trauma. In 14/94 (15%) soldiers the neck wound was believed to have been the sole cause of death, primarily from carotid artery damage, spinal cord transection or rupture of the larynx. COAT objectively demonstrated that despite the larger OSPREY collar having almost double the surface area than the two-piece prototype collar, the percentage area of vulnerable cervical structures left exposed only reduced from 16.3% to 14.4%.

DISCUSSION

COAT demonstrated its ability to objectively quantify the potential effectiveness of different body armour designs in providing coverage of vulnerable anatomical structures from different shot line orientations. To improve its utility, it is recommended that COAT be further developed to enable weapon and tissue specific information to be modelled, and that clinically significant injuries to other body regions are also incorporated.

Left Atrial Anatomy in Patients Undergoing Ablation for Atrial Fibrillation

Background: Left atrial anatomy is highly variable, asymmetric, irregular and three-dimensionally unique. This variability can affect the outcome of atrial ablation. A catalog of anatomic varieties may aid patient selection and ablation approach and provide better tools for left atrial ablation. Methods: We analyzed computed tomography scans from 514 patients undergoing left atrial ablation. Images were processed on Advantage Windows with CardEP™ software (GE Healthcare, Waukesha, WI). Measurements of pulmonary vein (PV) ostial size along the long and short axes were made using double oblique cuts, and area of the ostia was calculated. Results: Patients with 2 left (LPV) and 2 right PVs (RPV) (62.6%), 2 LPVs and 3 RPVs (17.3%) and 1 LPV and 2 RPVs (14.2%) made up the three most common variants. In the 2-LPV/2-RPV anatomy, the ostial size and area of the RPVs were larger than their corresponding LPVs (p<0.001), and the ostial size and area of the superior PVs were larger than their corresponding inferior PVs (p<0.001). In the 2-LPV/3-RPV anatomy, the total area of the RPVs was larger than the total area of the LPVs (p<0.001). In the 1-LPV/2-RPV anatomy, the ostial size of the left common PV was larger than either right PV (p<0.007). However, the total area of the RPVs was larger than the area of the left common PV (p<0.002). The left common PV was also larger than any of the left veins in any of the other anatomies. The total PV area between the three most common anatomies was not significantly different. Conclusions: More than 37% of patients have a left atrial anatomy other than 2 left and 2 right PVs. This data may help in designing approaches for left atrial ablation, tailoring the procedure to individual patients and improving ablation tools.

Thermal bistability-based method for real-time optimization of ultralow-threshold whispering gallery mode microlasers

A method based on thermal bistability for ultralow-threshold microlaser optimization is demonstrated. When sweeping the pump laser frequency across a pump resonance, the dynamic thermal bistability slows down the power variation. The resulting line shape modification enables a real-time monitoring of the laser characteristic. We demonstrate this method for a functionalized microsphere exhibiting a submicrowatt laser threshold. This approach is confirmed by comparing the results with a step-by-step recording in quasi-static thermal conditions.