Citations

Purpose Noninvasive stiffness imaging techniques (elastography) can image myocardial tissue biomechanics in vivo. For cardiac MR elastography (MRE) techniques, the optimal vibration frequency for in vivo experiments is unknown. Furthermore, the accuracy of cardiac MRE has never been evaluated in a geometrically accurate phantom. Therefore, the purpose of this study was to determine the necessary driving frequency to obtain accurate three‐dimensional (3D) cardiac MRE stiffness estimates in a geometrically accurate diastolic cardiac phantom and to determine the optimal vibration frequency that can be introduced in healthy volunteers. Methods The 3D cardiac MRE was performed on eight healthy volunteers using 80 Hz, 100 Hz, 140 Hz, 180 Hz, and 220 Hz vibration frequencies. These frequencies were tested in a geometrically accurate diastolic heart phantom and compared with dynamic mechanical analysis (DMA). Results The 3D Cardiac MRE was shown to be feasible in volunteers at frequencies as high as 180 Hz. MRE and DMA agreed within 5% at frequencies greater than 180 Hz in the cardiac phantom. However, octahedral shear strain signal to noise ratios and myocardial coverage was shown to be highest at a frequency of 140 Hz across all subjects. Conclusion This study motivates future evaluation of high‐frequency 3D MRE in patient populations. Magn Reson Med 77:351–360, 2017. © 2016 Wiley Periodicals, Inc.

Background Physical activity data are collected automatically by implantable cardioverter‐defibrillators ( ICD s). Though these data potentially provide a quantifiable and easily accessible measure of functional status, its relationship with survival has not been well studied. Methods and Results Patients enrolled in the Boston Scientific LATITUDE remote monitoring system from 2008 to 2012 with ICD s were eligible. Remote monitoring data were used to calculate mean daily activity at baseline (30 to 60 days after implantation), and longitudinally. Cox regression was used to examine the association between survival and increments of 30 minutes/day in both (1) mean baseline activity and (2) time‐varying activity, with both adjusted for demographic and device characteristics. A total of 98 437 patients were followed for a median of 2.2 years (mean age of 67.7±13.1 years; 71.7% male). Mean baseline daily activity was 107.5±66.2 minutes/day. The proportion of patients surviving after 4 years was significantly higher among those in the most versus least active quintile of mean baseline activity (90.5% vs. 50.0%; log‐rank P value, <0.001). Lower mean baseline activity (i.e., incremental difference of 30‐minutes/day) was independently associated with a higher risk of death (adjusted hazard ratio [ AHR ], 1.44; 95% confidence interval [ CI ], 1.427 to 1.462). Time‐varying activity was similarly associated with a higher risk of death ( AHR , 1.48; 95% CI , 1.451 to 1.508), indicating that a patient having 30 minutes per day less activity in a given month has a 48% increased hazard for death when compared to a similar patient in the same month. Conclusions Patient activity measured by ICD s strongly correlates with survival following ICD implantation.

SummaryThe cardiac effects of hypercalcaemia are usually manifest as a shortening of the QT-interval. Hypercalcaemia is infrequently associated with a clinically manifest arrhythmia. However, concomitant therapy with digoxin or underlying cardiac disease can potentiate the arrhythmogenic effects of hypercalcaemia, leading to a symptomatic rhythm disorder. We describe a symptomatic arrhythmia, which developed in a patient with hypercalcaemia secondary to squamous cell carcinoma of the bronchus. The patient was on digoxin therapy at the time. The arrhythmia did not recur after discontinuation of digoxin therapy and correction of the hypercalcaemia. Because of its effect on cardiac conduction, hypercalcaemia should be considered in the evaluation of any patient with an unexplained bradyarrhythmia. Conversely, patients with hypercalcaemia should discontinue digoxin therapy and be evaluated for the presence of rhythm disorders while receiving appropriate treatment for hypercalcaemia.

Background— Prompt recognition of underlying cardiovascular implantable electronic device (CIED) infection in patients presenting with Staphylococcus aureus bacteremia (SAB) is critical for optimal management of these cases. The goal of this study was to identify clinical predictors of CIED infection in patients presenting with SAB and no signs of pocket infection. Methods and Results— All cases of SAB in CIED recipients at Mayo Clinic from 2001 to 2011 were retrospectively reviewed. We identified 131 patients with CIED who presented with SAB and had no clinical signs of device pocket infection. Forty-five (34%) of these patients had underlying CIED infection based on clinical or echocardiographic criteria. The presence of a permanent pacemaker rather than an implantable cardioverter-defibrillator (odds ratio, 3.90; 95% confidence interval, 1.65–9.23; P =0.002), >1 device-related procedure (odds ratio, 3.30; 95% confidence interval, 1.23–8.86; P =0.018), and duration of SAB ≥4 days (odds ratio, 5.54; 95% confidence interval, 3.32–13.23; P <0.001) were independently associated with an increased risk of CIED infection in a multivariable model. The area under the receiver operating characteristics curve for the multivariable model was 0.79, indicating a good discriminatory capacity to distinguish SAB patients with and without CIED infection. Conclusions— Among patients presenting with SAB and no signs of pocket infection, the risk of underlying CIED infection can be calculated based on the type of device, number of device-related procedures, and duration of SAB. We propose that patients without any of these high-risk features have a low risk of underlying CIED infection and may be monitored closely without immediate device extraction. Prospective studies are needed to validate this risk prediction model.

Femoral ExtractionLaser and radiofrequency energy–assisted lead extraction has greatly facilitated this complex procedure. Although success rates are high, in some instances alternate methods of extraction are required. In this review, we discuss techniques for femoral extraction of implanted leads and retained fragments. The major tools available, including commonly used snares and delivery tools, are discussed. We briefly describe combined internal jugular and femoral venous extraction approaches, as well as complimentary utilization of more than one technique via the femoral vein. Animated and procedural sequences are included to help the reader visualize the key components of these techniques.

Abstract Aims Prognostic benefit from CRT compared with controls is well established. Symptomatic response rates, however, are controversial and have never been systematically evaluated with standard subtraction of control rates to establish the incremental symptomatic response effect of CRT pacing. Methods and results First, we identified 150 consecutive CRT papers and assessed researchers’ perceptions of the symptomatic response to CRT. The mean quoted response rate was 66%. Only 26 studies acknowledged the existence of response without the device. Secondly, we examined actual symptomatic response rates in the randomized trials (CARE-HF, COMPANION, CONTAK-CD, MIRACLE, MIRACLE-ICD, MIRACLE-ICD II, MUSTIC, and REVERSE) totalling 3904 patients. The NYHA status improved in 51% of those randomized to CRT vs. 35% of controls (incremental effect 16%). This incremental improvement was significantly greater in open studies (with no device for controls) than in blinded studies (control arm receiving a device but no CRT, such as a defibrillator or a CRT programmed off), 20% vs. 13%, P &lt; 0.001. Conclusions Quoting CRT responder rates in isolation without recognizing spontaneous ‘response’ is common but unwise. The incremental symptomatic response rate from CRT pacing is ∼16%, much lower than widely reported. This value is similar to that for drugs in heart failure and should not be considered disappointing: they both exert powerful prognostic benefits. For scientific purposes, e.g. to explore potential improvements, symptomatic benefit from CRT should be quantified, like all other effects, by comparison with a control.

Background —In a previous randomized trial, the 12F laser sheath removed pacing leads via the implant vein more successfully than traditional mechanical tools alone. Two larger sizes of laser sheath, the 14F and 16F models, were developed to extract defibrillator leads and large-diameter pacing leads implanted for the chronic. These devices use pulsed ultraviolet laser light to core though fibrotic tissue grown over the lead body to free the lead from the vasculature. A mandatory prospective registry studied the safety and effectiveness profiles of the larger laser sheaths vis-à-vis the 12F laser sheath. Methods and Results —In this study, 863 patients underwent extraction of 1285 leads at 52 sites. Patients treated with the 14F device tended to have older leads than the 12F population; the 16F population, which comprised mostly defibrillator patients, were younger, had younger leads, and were more often male than the 12F population. Clinical success (extracting the entire lead or the lead body minus the distal electrode) was observed in 91% to 92% of cases for all device sizes. The overall complication rate was 3.6%, with 0.8% perioperative mortality. Incidence of complications was independent of laser sheath size. Conclusions —The 14F and 16F laser sheaths offer an extraction option for larger long-term transvenous pacemaker and defibrillator leads that is as safe and effective as the 12F laser sheath.