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Balanced steady-state free precession (bSSFP) is important in cardiac MRI but suffers from off-resonance artifacts. The interpretation-limiting artifacts in patients with cardiac implants remain an unsolved issue.To develop an interleaved radial linear combination bSSFP (lcSSFP) method with partial dephasing (PD) for improved cardiac cine imaging when implanted cardiovascular devices are present.Prospective.Flow phantom adjacent to a pacemaker and 10 healthy volunteers (mean age ± standard deviation: 31.9 ± 2.9 years, 4 females) with a cardioverter-defibrillator (ICD) positioned extracorporeally at the left chest in the prepectoral region.A 3-T, 1) Cartesian bSSFP, 2) Cartesian gradient echo (GRE), 3) Cartesian lcSSFP, and 4) radial lcSSFP cine sequences.Flow artifacts mitigation using PD was validated with phantom experiments. Undersampled radial lcSSFP with interleaving across phase-cyclings and cardiac phases (RLC-SSFP), combined with PD, was then employed for achieving improved quality of cine images from left ventricular short-axis view. The image quality in the presence of cardiac devices was qualitatively assessed by three independent raters (1 = worst, 5 = best), regarding five criteria (banding artifacts, streak artifacts, flow artifacts, cavity visibility, and overall image quality).Wilcoxon rank-sum test for the five criteria between Cartesian bSSFP cine and RLC-SSFP with PD. Fleiss kappa test for inter-reader agreement. A P value 0.05 was considered statistically significant.Based on simulations and phantom experiments, 60 projections per phase cycling and 1/6 PD were chosen. The in vivo experiments demonstrated significantly reduced banding artifacts (4.8 ± 0.4 vs. 2.7 ± 0.7), fewer streak artifacts (3.7 ± 0.6 vs. 2.6 ± 0.7) and flow artifacts (4.4 ± 0.4 vs. 3.7 ± 0.6), therefore improved cavity visibility (4.1 ± 0.4 vs. 2.9 ± 0.9) and overall quality (4.0 ± 0.4 vs. 2.7 ± 0.7).RLC-SSFP method with PD may improve cine image quality in subjects with cardiac devices.2.Stage 1.

Post-traumatic stress disorder (PTSD) has been associated with cardiovascular disease (CVD), but the mechanisms remain unclear. Autonomic dysfunction, associated with higher CVD risk, may be triggered by acute PTSD symptoms. We hypothesized that a laboratory-based trauma reminder challenge, which induces acute PTSD symptoms, provokes autonomic dysfunction in a cohort of veteran twins. We investigated PTSD-associated real-time physiologic changes with a simulation of traumatic experiences in which the twins listened to audio recordings of a one-minute neutral script followed by a one-minute trauma script. We examined two heart rate variability metrics: deceleration capacity (DC) and logarithmic low frequency (log-LF) power from beat-to-beat intervals extracted from ambulatory electrocardiograms. We assessed longitudinal PTSD status with a structured clinical interview and the severity with the PTSD Symptoms Scale. We used linear mixed-effects models to examine twin dyads and account for cardiovascular and behavioral risk factors. We examined 238 male Veteran twins (age 68 ± 3 years old, 4% black). PTSD status and acute PTSD symptom severity were not associated with DC or log-LF measured during the neutral session, but were significantly associated with lower DC and log-LF during the traumatic script listening session. Long-standing PTSD was associated with a 0.38 (95% confidence interval, −0.83,− 0.08) and 0.79 (−1.30, −0 .29) standardized unit lower DC and log-LF, respectively, compared to no history of PTSD. Traumatic reminders in patients with PTSD lead to real-time autonomic dysregulation and suggest a potential causal mechanism for increased CVD risk, based on the well-known relationships between autonomic dysfunction and CVD mortality.

PURPOSE Segmentation of contrast-enhanced CT and measurement of SPECT point spread function (PSF) are usually required for conventional partial volume correction (PVC). This study was to develop a segmentation-free method with blind deconvolution (BD) and anatomical-based filtering for SPECT PVC. METHODS The proposed method was implemented using an iterative BD algorithm to estimate the restored image and the PSF simultaneously. An anatomical-based filtering was implemented at each iteration to reduce Gibbs artifact and suppress noise amplification in the deconvolution process. The proposed method was validated with 123 I-metaiodobenzylguanidine (123 I-mIBG) SPECT/CT imaging of NCAT phantoms with and without myocardial perfusion defect and a physical cardiac phantom. Fifteen heart-to-mediastinum ratios (HMRs) were configured in the NCAT and physical phantoms. Correlations between SPECT-quantified and true HMRs were calculated from images without PVC as well as from BD restored images. The proposed method was also performed on a human 123 I-mIBG study. RESULTS Relative bias and standard deviation images of NCAT phantoms showed that the proposed method reduced both bias and noise. Mean relative bias in the simulated normal myocardium was markedly improved (-16.8% ± 0.4% versus -0.8% ± 0.6% for low noise level; -16.7% ± 0.7% versus -2.3% ± 0.9% for high noise level). Mean relative bias in the simulated myocardial defect was also noticeably improved (-12.7% ± 1.2% versus 1.2% ± 1.6% for low noise level; -13.5% ± 2.4% versus -0.9% ± 2.8% for high noise level). The signal to noise ratio (SNR) of the defect was improved from 2.95 ± 0.09 to 4.07 ± 0.16 for low noise level (38% increase of mean), and from 2.56 ± 0.15 to 3.62 ± 0.22 for high noise level (41% increase of mean). For both NCAT and physical phantoms, HMRs calculated from images without PVC were underestimated (correlations between SPECT-quantified and true HMRs: y = 0.81x + 0.1 for NCAT phantom; y = 0.82x + 0.14 for physical phantom). HMRs from BD restored images were markedly improved (correlations between SPECT-quantified and true HMRs: y = x + 0.05 for NCAT phantom; y = 0.97x - 0.12 for physical phantom). After applying the proposed PVC method, the estimation error between the SPECT-quantified and true HMRs was significantly reduced from -0.75 ± 0.57 to 0.04 ± 0.17 for NCAT phantom (P = 8e-05), and from -0.68 ± 0.67 to -0.26 ± 0.42 for physical phantom (P = 0.005). The human study demonstrated that the HMR increased by 8% with PVC. CONCLUSIONS The proposed segmentation-free PVC method has the potential of improving SPECT quantification accuracy and reducing noise without the need for premeasuring the image PSF.

Purpose: A dedicated cardiac hybrid single photon emission computed tomography (SPECT)/CT scanner that uses cadmium zinc telluride detectors and multiple pinhole collimators for stationary acquisition offers many advantages. However, the impact of the reconstruction system matrix (SM) dimension on the reconstructed image quality from truncated projections and 19 angular samples acquired on this scanner has not been extensively investigated. In this study, the authors aimed to investigate the impact of the dimensions of SM and the use of body contour derived from adjunctive CT imaging as an object support in reconstruction on this scanner, in relation to background extracardiac activity. Methods: The authors first simulated a generic SPECT/CT system to image four NCAT phantoms with various levels of extracardiac activity and compared the reconstructions using SM in different dimensions and with/without body contour as a support for quantitative evaluations. The authors then compared the reconstructions of 18 patient studies, which were acquired on a GE Discovery NM570c scanner following injection of different radiotracers, including 99mTc-Tetrofosmin and 123I-mIBG, comparing the scanner's default SM that incompletely covers the body with a large SM that incorporates a patient specific full body contour. Results: The simulation studies showed that the reconstructions using a SM that only partially covers the body yielded artifacts on the edge of the field of view (FOV), overestimation of activity and increased nonuniformity in the blood pool for the phantoms with higher relative levels of extracardiac activity. However, the impact on the quantitative accuracy in the high activity region, such as the myocardium, was subtle. On the other hand, an excessively large SM that enclosed the entire body alleviated the artifacts and reduced overestimation in the blood pool, but yielded slight underestimation in myocardium and defect regions. The reconstruction using the larger SM with body contour yielded the most quantitatively accurate results in all the regions of interest for a range of uptake levels in the extracardiac regions. In patient studies, the SM incorporating patient specific body contour minimized extracardiac artifacts, yielded similar myocardial activity, lower blood pool activity, and subsequently improved myocardium-to-blood pool contrast (p < 0.0001) by an average of 7% (range 0%–18%) across all the patients, compared to the reconstructions using the scanner's default SM. Conclusions: Their results demonstrate that using a large SM that incorporates a CT derived body contour in the reconstruction could improve quantitative accuracy within the FOV for clinical studies with high extracardiac activity.

Exposure to racial discrimination has been linked to physiological reactivity. This study investigated self-reported exposure to racial discrimination and parasympathetic [high-frequency heart rate variability (HF-HRV)] and sympathetic (norepinephrine and cortisol) activity at baseline and then again after acute laboratory stress. Lifetime exposure to racial discrimination was measured with the Schedule of Racist Events scale. Thirty-two women (16 Black and 16 White) with type 2 diabetes performed a public speaking stressor. Beat-to-beat intervals were recorded on electrocardiograph recorders, and HF-HRV was calculated using spectral analysis and natural log transformed. Norepinephrine and cortisol were measured in blood. Higher discrimination predicted lower stressor HF-HRV, even after controlling for baseline HF-HRV. When race, age, A1c and baseline systolic blood pressure were also controlled, racial discrimination remained a significant independent predictor of stressor HF-HRV. There was no association between lifetime discrimination and sympathetic markers. In conclusion, preliminary data suggest that among women with type 2 diabetes mellitus (T2DM), exposure to racial discrimination is adversely associated with parasympathetic, but not sympathetic, reactivity.

Background Advances in implantable cardioverter defibrillator (ICD) technology have resulted in more effective defibrillation, and the need for defibrillation threshold (DFT) testing has been questioned. Methods A total of 64,227 initial ICD implant procedures performed at 1,261 facilities (April to December 2010) in the NCDR Registry™ were selected to identify patterns of practice related to DFT testing. Patient, physician, and procedural characteristics were compared. Independent association of DFT testing with in-hospital adverse events or mortality was also examined. Results DFT testing was performed in 71% of patients. Patients who did not undergo testing were older; more often had heart failure, lower left ventricular ejection fraction, atrial arrhythmias, and a primary prevention indication; and were more likely to receive a cardiac resynchronization therapy device. In addition, patients who did not undergo testing were less likely to be implanted in a metropolitan area and more often implanted at a teaching hospital, in New England, in the Mid-Atlantic, or in the Pacific U.S . In-hospital adverse events occurred in 2.56% of patients who underwent DFT testing compared to 3.58% who did not (P < 0.001). Death or any complication remained more likely to occur in patients who did not undergo testing (odds ratio and 95% confidence interval: 1.46 [1.33, 1.61], P < 0.001), after adjusting for baseline and procedural differences. Conclusions DFT testing is not performed in many (29%) patients in clinical practice. Patients who did not undergo testing were more likely to have adverse events and to be older with more comorbidities, which could explain why DFT testing was avoided. Prospective randomized data are needed to determine the impact of DFT testing on outcome.

Background: Primary prophylaxis with implantable cardioverter-defibrillators (ICDs) improves mortality in patients at risk for sudden cardiac death (SCD). However, ICDs are highly underutilized. We explored patients’ attitudes and perceptions of ICDs to better understand potential patient-related barriers to appropriate utilization. Methods: Records of patients visiting three outpatient cardiology clinics (June 2009–January 2010) were reviewed and 133 with ejection fractions ≤35% and without an ICD were identified. Seventy-two met criteria for ICD placement. Twenty-five consented and were interviewed by telephone using a semistructured open-ended interview guide. Twelve individuals had accepted ICD referral, and 13 had declined. We analyzed transcripts of ICD refusers and acceptors using the constant comparative method of grounded theory. Results: Five major themes emerged: (1) Patients who refused ICD referral demonstrated a lack of insight into their own risk potential. (2) Many patients who accepted ICD referral perceived that this was strongly recommended by their physicians, although many patients refusing did not. (3) Concerns over recall, malfunction, and surgical risk were common in both. (4) Many patients demonstrated inaccurate perceptions of ICD-related risks and lifestyle changes. Acceptors often reported these perceptions being addressed by their physician. (5) Feelings regarding invasive life-prolonging interventions played an important role in ICD referral refusal for some individuals. Conclusions: Refusal of ICD is common among primary prevention candidates. Common themes in the decision-making process include insight into personal risk of SCD, and perceived strength of the physician recommendation. Providers may want to consider assessment of patients’ individual understanding and perceptions when discussing ICD prophylaxis. (PACE 2012; 35:1179–1187)

Background: Electrophysiology studies (EPS) have historically played a role in sudden death risk stratification. More recent studies point to the left ventricular ejection fraction (EF) as a guide to implantable cardioverter defibrillators (ICD) implantation. The extent of EPS use in patients undergoing ICD implantation in the current era remains unknown. Methods: Patients undergoing de novo ICD implantation in the ICD Registry between September 2006 and March 2009 who also underwent EPS within 30 days before implant were compared to the remaining cohort to identify clinical characteristics that correlated with EPS performance. Multivariate models were generated using hierarchical logistic regression analysis. Results: EPS were performed in 33,786 of 275,273 patients. Those undergoing EPS were more likely to have had a history of syncope, family history of sudden death, lack of congestive heart failure, narrower QRS intervals, and higher EF. Overall, 63.9% of EPS were performed in patients receiving primary prevention ICDs. Ventricular tachyarrhythmias were induced in 46.1% of primary prevention and 54.2% of secondary prevention ICD recipients. Monomorphic ventricular tachycardia was the most common type of arrhythmia induced in both groups. Complication rates were not higher in those undergoing EPS. Conclusions: EPS were performed predominantly in patients with borderline or less well-defined risk factors for sudden death. Ventricular arrhythmias induced from EPS were not uncommon and may help identify individuals at higher risk for future ICD therapies. Efforts to better define the role of EPS in patients undergoing ICD implantation should be considered. (PACE 2012; 35:912–918)

Impact of Recalls on ICD Utilization. Introduction: Underutilization of ICDs is well documented. It has been hypothesized that device recalls, and the resultant negative publicity, may contribute. Methods and Results: To determine if the October 2007 recall of the Medtronic Fidelis lead was associated with a decrease in volume of ICD procedures in the United States, we analyzed data submitted to the ICD Registry™ between July 2006 and December 2008. Time-series analyses were performed comparing actual and predicted implant volumes following the recall, using monthly data from July 2006 to September 2007 to establish a trend line. Observed data points falling outside the 95% CIs from the trend line were considered statistically significant. The study cohort includes 173,616 implantations in 658 hospitals. Before October 2007, an average of 5,952 devices, 4,910 for primary prevention, were implanted per month. Following the recall, the average monthly number of implants was modestly lower at 5,623 (P = 0.05), 4,601 for primary prevention (P = 0.01.) However, as volume was decreasing prior, in time-series analysis, the observed monthly implant volume for primary prevention devices differed from expected based on the trend line for only 1 month. The proportion of Medtronic implants declined from 51.1% in the 15 months prior to the recall to 45.8% in the 15 months of the recall or after (P

Background: Clinical formulas for QT correction utilize instantaneous HR. We showed previously that longer-term HR affects QT duration. We extend these findings, identifying more accurate models of QT behavior. Method: Multiple models of QT dependence on HR were tested in 2 independent populations. Holter recordings were analyzed in population A (healthy volunteers, n = 14, 6 males, age 26.9 ± 12.3 yr). The hypotheses generated in population A were tested in an independent group population B, healthy volunteers, n = 15, 9 males, age 52.9 ± 15.6 yr). Linear models of QT interval dependence on a weighted average of RR intervals in the preceding 3 minutes were compared to models based on the immediately preceding RR interval (instantaneous HR). Results: In population A, linear models based on RR intervals over the preceding minute performed better than the best nonlinear model based on the single RR interval immediately preceding the QT interval. Linear models including HR values preceding the QT interval by more than 60 s further improved model fit. This model hierarchy was confirmed in population B. Linear formula for QT correction based on exponential decay of HR effect with 60 s time constant outperformed Bazett and Fridericia formulas in both populations. Conclusions: QT duration in normal ambulatory subjects is affected by noninstantaneous HR, including HR history dating back more than 60 s. Exponential decay of this “memory effect” with time constant of 1 minute provides an accurate description of QT adaptation. This may be of clinical importance when HR is not steady. Ann Noninvasive Electrocardiol 2011;16(2):148–155

Background: Symptoms are among the most important factors impacting quality of life (QOL) in hypertrophic cardiomyopathy (HCM) patients, and reflect a poor prognosis. Whether emotional stress can trigger symptoms of chest pain, dyspnea, palpitations, and lightheadedness has not been described. Methods: Members of the Hypertrophic Cardiomyopathy Association (HCMA) received an electronic link via e-mail to an ongoing online survey, also accessed via links on the HCMA message-board and homepage. Between May 2007 and November 2008, there were 1,297 respondents. The survey queried demographic and self-reported clinical information, and types and triggers of symptoms. Respondents reported physical and emotional QOL on a 1–10 Likert scale. Results: Symptoms reported included chest pain (49%), dyspnea (70%), palpitations (61%), and syncope/lightheadedness (59%). The most common symptom trigger was exertion, 64% describing symptoms while climbing stairs or hills. Forty-nine percent described experiencing symptoms during emotional stress. Those reporting chest pain were more likely to report emotion triggering (60%) than those reporting palpitations, syncope/lightheadedness, or dyspnea (50–54% each). Both physical and emotional QOL were significantly decreased in those describing emotion-triggered symptoms. Women were more likely than men to report symptoms overall, as well as emotion-triggered symptoms (50% vs 35%, P < 0.001) and exertion-triggered symptoms (79% vs 58%, P < 0.001). After controlling for presence of symptoms, both emotion- and exertion-triggered symptoms remained significantly more common in women. Conclusions: Triggering of symptoms by emotion is common in individuals with HCM. Further studies will determine pathways linking emotional stressors with chest pain, dyspnea, palpitations, and lightheadedness in these patients. (PACE 2010; 33:1047–1053)

ICD Shocks Increase TWA. Introduction: While implantable defibrillator shocks save lives, shock can lead to ventricular arrhythmias. However, the mechanism of shock-related proarrhythmia remains unclear. We evaluated the impact of ICD shock on repolarization instability, a factor associated with ventricular arrhythmogenesis. Methods and Results: Sixty-five patients with ICDs underwent ambulatory ECG monitoring during defibrillation testing 3 months postimplant. TWA was analyzed continuously in the time domain during baseline, sedated, and post-shock states. RR, QRS, and QT intervals and catecholamines were also measured continuously. Adequate pre- and post-shock Holter data were recorded in 55 patients, 48 male, mean 64 ± 12 years, 50 with coronary disease, 48 with prior spontaneous or induced arrhythmia. TWA significantly increased after shock, from 9.6 ± 0.5 to 11.9 ± 0.6 µV, as did QRS duration, epinephrine, and norepinephrine levels, compared with sedated and baseline states. RR intervals decreased minimally. TWA changes with shock were not associated with RR or QRS duration changes, but were associated with changes in epinephrine. Conclusions: ICD shock, even in the sedated state, increases repolarization instability as measured by TWA, an effect mediated in part by sympathetic stimulation. This association between shock and TWA may have important mechanistic and clinical implications for optimization of defibrillation therapy. (J

Psychological Stress and Repolarization. Introduction: Psychological stress can precipitate ventricular arrhythmias in patients with ICDs, as well as sudden death. However, the physiologic pathways remain unknown. We sought to determine whether psychological stress induced in the laboratory setting alters indices of repolarization associated with arrhythmogenesis. Methods and Results: Patients with ICDs and a history of ventricular arrhythmia underwent ambulatory ECG monitoring during a laboratory mental stress protocol (anger recall and mental arithmetic). Continuous changes in repolarization indices which have correlated with temporal and spatial myocardial heterogeneity of repolarization, including T-wave alternans (TWA), T-wave amplitude (Tamp), and T-wave area (Tarea) were analyzed in the time domain. In the 33 patients (85% male, 88% with coronary artery disease, mean ejection fraction 30%), norepinephrine, epinephrine, BP, and HR increased during mental stress. TWA increased from 22 (interquartile range 16-27) at baseline to 29 (21-38) uV during mental stress (P < 0.001). Changes in TWA correlated with changes in HR, systolic BP, and catecholamines. Tamp and Tarea also increased with mental stress (P < 0.01) but did not correlate with changes in other variables. Conclusion: Psychological stress increased TWA, Tamp, and Tarea. Autonomically mediated repolarization changes may be a pathophysiologic link between emotion and arrhythmia in susceptible patients.

Although the problem of ICD sensing of paced ventricular stimuli has been resolved by incorporation of VVI pacing into current ICDs, many patients required separate DDD pacemakers. We report a problematic PM-ICD interaction: the inability to prevent sensing of paced atrial stimuli ("atrial sensing") leading to double-counting in DDD-PM-requiring patients with transvenous (TV) ICDs with aggressive autogain sensing (CPI Ventak PRxII or III). Four of eight patients receiving both transvenous DDD PMs and ICDs (CPI Endotak lead, at the RV apex), had atrial sensing, leading to double counting, despite intraoperative testing of multiple atrial locations with an active fixation lead. Five patients had a PRxII/III ICD, four with atrial sensing (80%), and three a PRx without atrial sensing. Patients with atrial sensing were not distinguished by any clinical or device related variable. In patients with atrial sensing (all with heart block), the PM was programmed to VDD mode. No patient has received inappropriate therapy or failed to sense VF in follow-up. In many patients with TV ICDs who required DDD pacing, no atrial position can be found without ICD sensing of atrial stimuli. While in patients with heart block this problem can be circumvented by programming to the VDD mode, in patients with sinus incompetence it may only be resolved by the combination ICD-DDD PM, currently in development.

The CPI PRxII is a recently approved, multitiered implantable cardioverter defibrillator (ICD) that delivers high and low energy biphasic shocks, antitachycardia (ATP) and bradycardia pacing, and stores 2.5 minutes of electrograms from the widely spaced shocking electrodes. The PRxII was implanted in 58 patients at Yale-New Haven Hospital between December 1993 and January 1995. At implant, mean biphasic defibrillation threshold (DFT) in patients with testing to failure was 10 J (1-20). All 36 patients who were candidates for a new transvenous system underwent successful nonthoracotomy implantation. Based on noninvasive predischarge EPS results, 30 patients had > or = 1 VT zone: 21 patients had ATP, 9 others had first shock < or = 5 J. During follow-up, 13 patients had been treated for 379 events (range, 1-127). Of 340 events in a zone with ATP, 97% responded to ATP, 3% required shock. First programmed shock converted all events in a VF zone. Details, including RR intervals, were available for all events in 15 of 17 patients receiving appropriate or inappropriate therapy or diverted shocks. One hundred eleven of 148 available electrograms confirmed VT by morphology, rate, and/or presence of AV dissociation. In nine patients, electrogram data altered therapy through diagnosis of inappropriate or diverted therapy, guidance of detection enhancements, or diagnosis of previously unrecognized VTs. We conclude the PRxII achieves low DFTs that obviate the need for thoracotomy and effectively treats ventricular arrhythmias with ATP and shock, with programming guided by noninvasive electrophysiology. Multiple stored electrograms from widely spaced shocking electrodes greatly enhance diagnostic capabilities, facilitating effective treatment.