The publication data currently available has been vetted by Vanderbilt faculty, staff, administrators and trainees. The data itself is retrieved directly from NCBI's PubMed and is automatically updated on a weekly basis to ensure accuracy and completeness.
If you have any questions or comments, please contact us.
BACKGROUND - The use of cardiac implantable electronic devices (CIEDs) has expanded dramatically over the past decade, but net clinical benefit has been curtailed by increasing infectious complications. In particular, CIED-related infectious endocarditis (IE) is a serious condition with significant morbidity and mortality.
METHODS - We performed a single-center, retrospective study between July 2006 and February 2011 with CIED-related IE, defined by either lead vegetations detected on echocardiography or by fulfilling Duke criteria for definite endocarditis. Clinical parameters and outcomes were detailed by electronic medical record review and vital status was confirmed by the Social Security Death Index.
RESULTS - Eighty patients (median age 67, interquartile range 56-75, 58 M/22 F) were diagnosed with CIED-related IE. Overall mortality was 36% with a median time to death of 95 days from presentation. Over half (52%) of the deaths were infection related with a median time to death of 29 days. Multivariate analysis showed methicillin-resistant Staphylococcus aureus (MRSA) infection (odds ratio [OR] 0.158; 95% confidence interval [CI], 0.047-0.534; P = .003) and concomitant valve endocarditis (OR 0.141, CI 0.041-0.491, P = .002) independently predicted mortality.
CONCLUSION - In this contemporary series, all-cause mortality in patients with CIED-related IE was high with a short time to death from onset of infection. MRSA and concomitant valve infection were the most powerful independent predictors of mortality.
©2014 Wiley Periodicals, Inc.
PURPOSE - To determine steady state milrinone concentrations in patients with stage D heart failure (HF) with and without renal dysfunction
METHODS - We retrospectively identified patients with stage D HF at a single medical center on continuous milrinonein fusion at the time of plasma collection for entry into a research registry database. Milrinone was prescribed and titrated to improve hemodynamic and clinical status by a cardiologist. Plasma samples were obtained at steady state milrinone concentrations. Patients were stratified by creatinine clearance (CrCl) into 4 groups: group 1 (CrCl >60 mL/min), group 2 (CrCl 60-30 mL/min), group 3 (CrCl <30 mL/min), and group 4 (intermittent hemodialysis). Retrospective chart review was performed to quantify the post milrinone hemodynamic changes by cardiac catheterization and electrophysiologic changes by implantable cardiac defibrillator (ICD) interrogation.
RESULTS - A total of 29 patients were identified: group 1 (n=14), group 2 (n=10), group 3(n=3), and group 4 (n = 2). The mean infusion rate (0.391+0.08 mg/kg/min) did not differ between groups (P=0.14). The mean milrinone concentration was 451+243 ng/mL in group 1, 591+293 ng/mL in group 2, 1575+962 ng/mL in group 3, and 6252+4409 ng/mL in group 4 (P<0.05 compared to groups 1). There was no difference in post milrinone hemodynamic improvements between the groups (P=0.41). The ICD interrogation revealed limited comparisons, but 6 of the 8 post milrinone ventricular tachycardia episodes requiring defibrillation occurred in group 4 patients.
CONCLUSION - Patients with stage D HF having severe renal dysfunction have elevated milrinone concentrations. Future studies of milrinone concentrations are warranted to investigate the potential risk of life-threatening arrhythmias and potential dosing regimens in renal dysfunction.
Coronary vasospasm is an unusual cause of angina and myocardial ischemia, with the potential to provoke acute myocardial infarction, malignant cardiac arrhythmias, and sudden cardiac death. The diagnosis is largely clinical and requires a high index of suspicion. Provocation studies are rarely performed due to the risks of the procedure and the relatively low incidence of disease. A subset of patients does not respond to conventional medical therapy and a paucity of evidence exists to guide therapy. While generally believed a multifocal phenomenon, there have been reports of successful treatment of focal, refractory vasospasm with coronary stent implantation. Furthermore, consideration of an implantable cardioverter defibrillator is warranted when vasospasm is complicated by lethal ventricular arrhythmias.
BACKGROUND - The D1275N SCN5A mutation has been associated with a range of unusual phenotypes, including conduction disease and dilated cardiomyopathy, as well as atrial and ventricular tachyarrhythmias. However, when D1275N is studied in heterologous expression systems, most studies show near-normal sodium channel function. Thus, the relationship of the variant to the clinical phenotypes remains uncertain.
METHODS AND RESULTS - We identified D1275N in a patient with atrial flutter, atrial standstill, conduction disease, and sinus node dysfunction. There was no major difference in biophysical properties between wild-type and D1275N channels expressed in Chinese hamster ovary cells or tsA201 cells in the absence or presence of β1 subunits. To determine D1275N function in vivo, the Scn5a locus was modified to knock out the mouse gene, and the full-length wild-type (H) or D1275N (DN) human SCN5A cDNAs were then inserted at the modified locus by recombinase mediated cassette exchange. Mice carrying the DN allele displayed slow conduction, heart block, atrial fibrillation, ventricular tachycardia, and a dilated cardiomyopathy phenotype, with no significant fibrosis or myocyte disarray on histological examination. The DN allele conferred gene-dose-dependent increases in SCN5A mRNA abundance but reduced sodium channel protein abundance and peak sodium current amplitudes (H/H, 41.0±2.9 pA/pF at -30 mV; DN/H, 19.2±3.1 pA/pF, P<0.001 vs. H/H; DN/DN, 9.3±1.1 pA/pF, P<0.001 versus H/H).
CONCLUSIONS - Although D1275N produces near-normal currents in multiple heterologous expression experiments, our data establish this variant as a pathological mutation that generates conduction slowing, arrhythmias, and a dilated cardiomyopathy phenotype by reducing cardiac sodium current.
BACKGROUND - Increased rates of complications related to the use of small-diameter implantable cardioverter-defibrillator (ICD) leads have been reported. Lead design and engineering aimed at reducing ICD lead diameter may increase associated subacute complications, including cardiac perforation, lead dislodgement, or lead failure.
OBJECTIVE - The purpose of this study was to determine whether lead caliber altered the risk of perforation, lead dislodgement, or lead failure in a single center.
METHODS - All patients with right ventricular (RV) ICD lead implantation at Vanderbilt University and VA-Nashville Medical Center between January 1, 2007, and August 31, 2007, were included in this study. Leads implanted during this period were the Riata 1580, Riata ST 7000 (St. Jude Medical, St. Paul, MN), Sprint Fidelis 6949, and Sprint Quattro 6947 (Medtronic, Minneapolis, MN). Information was collected retrospectively.
RESULTS - A total of 305 ICD leads were implanted (138 small diameter, 167 standard diameter) during the study period. Failure was defined as development of high pacing threshold, marked sensing change, cardiac perforation, or development of extracardiac stimulation. A total of 11 lead failures occurred in the small-diameter lead group, versus one in the standard group. Implantation of a small-diameter lead (Riata 1580, Riata ST 7000, or Sprint Fidelis 6949) was associated with a significant increase in failure rate, 8.0% versus 0.6% (P = .0008) compared with standard-size leads (Sprint Quattro 6947).
CONCLUSIONS - Subacute lead-related complications were more likely with use of small-diameter ICD leads (Riata 1580, Riata ST 7000, Sprint Fidelis 6949) than with with standard-caliber ICD leads (Sprint Quattro 6947).
Four cases of ICD system malfunction occurring within the Medtronic Marquis family over a limited time frame are reported. These cases shared a common element of defective connections between the header post and the right ventricular pace/sense terminal pin that required intervention and reconnection. Inappropriate shocks occurred in two cases. The circumstances of these cases provide important information about the potential difficulties with these devices and highlight the deficiencies of the current system in tracking and analyzing device-related problems.
INTRODUCTION - In acute canine studies, lidocaine, but not procainamide, increases defibrillation energy requirements. We evaluated the effects of lidocaine or procainamide on defibrillation energy requirements in 27 patients undergoing intraoperative testing for implantable cardioverter defibrillator device placement.
METHODS AND RESULTS - Patients were tested off antiarrhythmic drugs and again following either lidocaine (200 to 250 mg loading and 3 mg/min maintenance infusions) or procainamide (1 gm loading and 3 to 4 mg/min maintenance infusions). The defibrillation testing protocol consisted of initial testing at 15 J, followed by higher or lower energies to determine the lowest energy producing three consecutive successful defibrillations. Overall, the mean defibrillation energy increased from 14 +/- 5 J to 18 +/- 7 J during lidocaine (plasma concentration 5.1 +/- 1.6 micrograms/mL; P < 0.02) but were similar at baseline (12 +/- 5 J) and during procainamide infusion (13 +/- 6 J) (plasma concentration: procainamide 10.7 +/- 7.2 micrograms/mL; N-acetyl procainamide 1.0 +/- 0.4 micrograms/mL). A positive linear correlation was found between lidocaine plasma concentration and percent change in defibrillation energy (lidocaine: r = 0.61; P = 0.01). Procainamide raised the defibrillation energy in three patients, two with supratherapeutic plasma concentrations. The increase in defibrillation energy equaled or exceeded 25 J in four patients after lidocaine and in one patient after procainamide.
CONCLUSION - The data suggest that at high plasma concentrations, lidocaine and procainamide adversely affect defibrillation energy requirements consistent with an adverse, concentration-dependent effect of sodium channel blockade on defibrillation energy requirements in patients.