Publications by authors named "Jason Koontz"

Hantaan virus (HTNV) and Puumala virus (PUUV) are pathogenic zoonoses found in Asia and Europe, respectively. We conducted a randomized Phase 1 clinical trial of individual HTNV and PUUV DNA vaccines targeting the envelope glycoproteins (GnGc), as well as a combined HTNV/PUUV DNA vaccine delivered at varying doses using the PharmaJet Stratis® needle-free injection system (NCT02776761). Cohort 1 and 2 vaccines consisted of 2 mg/vaccination of HTNV or PUUV plasmid, respectively.

View Article and Find Full Text PDF
Article Synopsis
  • A study at Duke University Hospital reviewed 421 patients with left ventricular assist devices (LVADs) and implantable cardioverter-defibrillators (ICDs) to assess the frequency and causes of ICD shocks post-surgery.
  • Out of these patients, 33.9% experienced at least one shock, with 77.3% deemed appropriate and 22.7% inappropriate, primarily due to supraventricular tachycardia.
  • The findings suggest that better ICD programming, such as longer detection delays and higher rate cutoffs, could reduce the number of inappropriate shocks in LVAD recipients.
View Article and Find Full Text PDF

Introduction: Accurate localization of septal outflow tract premature ventricular contractions (PVCs) is often difficult due to frequent mid-myocardial or protected origin. Compared with traditional activation mapping, CARTO Ripple mapping provides visualization of all captured electrogram data without assignment of a specific local activation time and thus may enhance PVC localization.

Methods: Electroanatomic maps for consecutive catheter ablation procedures for septal outflow tract PVCs (July 2018-December 2020) were analyzed.

View Article and Find Full Text PDF
Article Synopsis
  • Atrial pacing and His-bundle pacing (HBP) may help improve heart function in patients with first-degree atrioventricular block (1°AVB), but traditional methods like RV pacing can lead to worse outcomes.
  • This study assessed the effects of different pacing techniques (atrial, AH-sequential, and AV-sequential) on heart performance in patients with 1°AVB during atrial fibrillation procedures.
  • The results showed no significant differences in overall heart function or pressure measurements among the pacing methods, indicating that while atrial pacing prolonged PR intervals, it didn't lead to improved cardiac output or heart conditions.
View Article and Find Full Text PDF
Article Synopsis
  • Diabetes mellitus (DM) is linked to increased risk of recurrence in atrial fibrillation (AF) after catheter ablation, as shown in a study comparing outcomes between patients with and without DM.
  • The study analyzed 351 patients and found those with DM tended to be older, heavier, and had more persistent AF, but had similar rates of complications during the procedure.
  • After a median follow-up of nearly 30 months, patients with DM experienced significantly higher rates of AF recurrence, indicating that managing blood sugar levels may be crucial in these patients.
View Article and Find Full Text PDF
Article Synopsis
  • Ventricular arrhythmias (VAs) and electrical storm (ES) are common issues after left ventricular assist device (LVAD) surgery, but their long-term effects are not well understood.
  • A study at Duke University analyzed 730 LVAD patients from 2009 to 2020, finding that 10.7% experienced ES, often linked to increased mortality and occurring both shortly after and long after surgery.
  • Key risk factors for developing ES included previous VAs, use of antiarrhythmic drugs, and prior ventricular tachycardia ablation, yet the best treatment options for managing ES in these patients remain unclear.
View Article and Find Full Text PDF
Article Synopsis
  • The review discusses the use of stellate ganglion blockade (SGB) as a treatment for patients with severe ventricular arrhythmias that don't respond to other therapies.
  • SGB can significantly reduce the frequency of arrhythmias and defibrillation events for 24-72 hours, providing a critical window for additional treatments like catheter ablation or heart surgery.
  • The procedure is shown to be safe, even in patients on anticoagulants, and is effective across different types and causes of ventricular arrhythmias.
View Article and Find Full Text PDF
Article Synopsis
  • This study investigates the outcomes of patients who have both a subcutaneous implantable cardioverter-defibrillator (S-ICD) and a left ventricular assist device (LVAD) due to limited existing data on the topic.
  • A retrospective study at Duke University Hospital identified four patients with S-ICD after LVAD implantation, all of whom experienced electromagnetic interference (EMI) that led to inappropriate shocks in some cases.
  • The systematic review also revealed that EMI is common, especially in primary and secondary sensing vectors, but undersensing in an alternate vector may improve over time, possibly preventing the need for device surgery.
View Article and Find Full Text PDF
Article Synopsis
  • Catheter ablation is an effective treatment for atrial fibrillation (AF) in patients with heart failure (HF), and this study compares its efficacy between those with ischemic and nonischemic heart failure.
  • The research involved 242 patients, showing that nonischemic patients were generally younger and had better heart function, but overall outcomes in symptom relief and functional status were similar across both groups after the procedure.
  • Both groups experienced significant improvements in their symptoms and functional abilities post-ablation, and there was no notable difference in the recurrence of atrial arrhythmias at 12 months between ischemic (74%) and nonischemic patients (78%).
View Article and Find Full Text PDF

Background: Pulmonary wall isolation (PWI) is increasingly used as an adjunctive lesion set to compliment pulmonary vein isolation (PVI), especially in patients with persistent atrial fibrillation (AF). The objective was to compare outcomes of catheter ablation in patients with persistent AF undergoing PVI with and without adjunctive PWI.

Methods: We performed a retrospective study of 558 patients who underwent de novo and repeat ablation for persistent AF.

View Article and Find Full Text PDF

Background: Compared with medical therapy, catheter ablation of atrial fibrillation (AF) in patients with heart failure (HF) improves cardiovascular outcomes. Risk scores (CAAP-AF and APPLE) have been developed to predict the likelihood of AF recurrence after ablation, have not been validated specifically in patients with AF and HF.

Methods: We analyzed baseline characteristics, risk scores, and rates of AF recurrence 12 months postablation in a cohort of 230 consecutive patients with AF and HF undergoing PVI in the Duke Center for Atrial Fibrillation registry from 2009-2013.

View Article and Find Full Text PDF

There is overwhelming evidence that the microbiome must be considered when evaluating the toxicity of chemicals. Disruption of the normal microbial flora is a known effect of toxic exposure, and these disruptions may lead to human health effects. In addition, the biotransformation of numerous compounds has been shown to be dependent on microbial enzymes, with the potential for different host health outcomes resulting from variations in the microbiome.

View Article and Find Full Text PDF

More than 80,000 chemicals are in commercial use worldwide. Hepatic metabolism to toxic intermediates is often a key mechanism leading to tissue damage and organ dysfunction. Effective treatment requires prompt detection of hepatotoxicity, ideally with rapid, minimally invasive diagnostic assays.

View Article and Find Full Text PDF

The past decade has seen an increase in the development and clinical use of biomarkers associated with histological features of liver disease. Here, we conduct a comparative histological and global proteomics analysis to identify coregulated modules of proteins in the progression of hepatic steatosis or fibrosis. We orally administered the reference chemicals bromobenzene (BB) or 4,4'-methylenedianiline (4,4'-MDA) to male Sprague-Dawley rats for either 1 single administration or 5 consecutive daily doses.

View Article and Find Full Text PDF

Background: Few studies have examined outcomes of catheter ablation for atrial fibrillation (AF) in patients with heart failure (HF) with preserved ejection fraction (HFpEF).

Objective: The purpose of this study was to compare outcomes of AF ablation in patients with HFpEF vs HF with reduced ejection fraction (HFrEF).

Methods: We performed a retrospective study of 230 patients with HF who underwent AF ablation, including 97 (42.

View Article and Find Full Text PDF

We report the case of a 57-year-old man with a history of ischemic cardiomyopathy who presented to the hospital with recurrent episodes of ventricular tachycardia refractory to antiarrhythmic medications. Mapping identified a deep premature ventricular contraction focus in the anterolateral papillary muscle, an area that has been previously identified as difficult to treat with radiofrequency catheter ablation. The hospital course was complicated by cardiogenic shock and VT-storm, and the patient ultimately underwent surgical resection of the anterolateral papillary muscle with left ventricular assist device placement as a successful bridge to cardiac transplantation.

View Article and Find Full Text PDF

This study sought to identify an optimal rodent bedding and cage-change interval to establish standard procedures for the IVC in our rodent vivarium. Disposable cages were prefilled with either corncob or α-cellulose bedding and were used to house 2 adult Sprague-Dawley rats (experimental condition) or contained no animals (control). Rats were observed and intracage ammonia levels measured daily for 21 d.

View Article and Find Full Text PDF

Background: Restoration of sinus rhythm (SR) in patients with atrial fibrillation/atrial flutter (AF/AFL) is limited principally to direct current cardioversion. The multi-ion channel blocker vanoxerine may prove an effective alternative.

Objective: The purpose of this study was to assess vanoxerine, a 1,4-dialkylpiperazine derivative, for acute conversion of recent-onset, symptomatic AF and AFL.

View Article and Find Full Text PDF
Article Synopsis
  • This study investigates the use of acoustic radiation force impulse (ARFI) imaging to visualize changes in tissue stiffness after radiofrequency ablation (RFA) in canine subjects.
  • The main goals were to measure the displacements caused by ARFI in both ablated and unablated heart tissue and to evaluate the contrast and quality of ARFI images compared to standard echo images.
  • Results showed that ARFI images had a higher accuracy in identifying lesion sites and produced better contrast and contrast-to-noise ratios than conventional imaging methods.
View Article and Find Full Text PDF