Background: Patients receiving an implantable cardioverter defibrillator (ICD) report various types and degree of sleep disruptions, but little is known regarding their characteristics, duration, and associated factors. The purposes of this study were: (1) to describe the effect of a psychoeducational intervention on sleep quality and daytime sleepiness, (2) to describe patterns of sleep over time, and (3) to identify predictors of poor sleep in an ICD population. Methods: A randomized longitudinal intervention trial was designed to test the effects of a psychoeducational intervention, which included a sleep education and counseling session in patients receiving their initial ICD. Patients (n = 236; 75% men; mean age 58.4 [±11.2] from the PsychoEducationAl Intervention for ICD PatiEnts (PEACE) trial comprised the study population. Variables related to sleep were measured by the Pittsburgh Sleep Quality Inventory (PSQI) and Epworth Sleepiness Scale (ESS). Results: No psychoeducational intervention effects on sleep outcomes were observed. However, 67.2% of the patients reported poor sleep quality at baseline, and 56.8% had low sleep quality at 6 months based on PSQI scores > 5; one-third (32.6%) were excessively sleepy based on ESS scores ≥10 at 6 months. Anxiety, depression, physical function, pain intensity, and pain severity were all highly correlated to each other across time. Female gender was a significant covariate for the PSQI. New York Heart Association (NYHA) class was a significant covariate for sleepiness (Epworth). Conclusions: Low sleep quality and daytime sleepiness are found at time of insertion and over time in patients with ICD. Female gender, higher NYHA class, as well as two latent factors encompassing increased anxiety, depressive symptoms, and decreased physical function and increased pain, were significant predictors of poor sleep quality and sleepiness over time. These data help identify those at higher risk for sleep problems after ICD.
BACKGROUND: Atrial fibrillation (AF) is the most common cardiac arrhythmia. Although treatment options for AF exist, many patients cannot be maintained in normal sinus rhythm. Amiodarone is an effective medication for AF but has limited clinical utility because of off-target tissue toxicity.
METHODS: Here, we use a pig model of AF to test the efficacy of an amiodarone-containing polyethylene glycol-based hydrogel. The gel is placed directly on the atrial epicardium through the pericardial space in a minimally invasive procedure using a specially designed catheter.
RESULTS: Implantation of amiodarone-containing gel significantly reduced the duration of sustained AF at 21 and 28 days; inducibility of AF was reduced 14 and 21 days post-delivery. Off-target organ drug levels in the liver, lungs, thyroid, and fat were significantly reduced in animals treated with epicardial amiodarone gel compared with systemic controls in small-animal distribution studies.
CONCLUSIONS: The pericardium is an underutilized therapeutic site and may be a new treatment strategy for AF and other cardiovascular diseases.
Theoretical cardiac electrophysiology focuses on the dynamics of the membrane and sarcoplasmic reticulum ion currents; however, passive (e.g., membrane capacitance) and quasi-active (response to small signals) properties of the cardiac sarcolemma, which are quantified by impedance, are also important in determining the behavior of cardiac tissue. Theoretically, impedance varies in the different phases of a cardiac cycle. Our goal in this study was to numerically predict and experimentally validate these phasic changes. We calculated the expected impedance signal using analytic methods (for generic ionic models) and numerical computation (for a rabbit ventricular ionic model). Cardiac impedance is dependent on the phase of the action potential, with multiple deflections caused by a sequential activation and inactivation of various membrane channels. The two main channels shaping the impedance signal are the sodium channel causing a sharp and transient drop at the onset of action potential and the inward rectifying potassium channel causing an increase in impedance during the plateau phase. This dip and dome pattern was confirmed in an ex-vivo rabbit heart model using high-frequency sampling through a monophasic action potential electrode. The hearts were immobilized using a myosin-inhibitor to minimize motion artifacts. We observed phasic impedance changes in three out of four hearts with a dome amplitude of 2-4Ω. Measurement of phasic impedance modulation using an extracellular electrode is feasible and provides a non-invasive way to gain insight into the state of cardiac cells and membrane ionic channels. The observed impedance recordings are consistent with the dip and dome pattern predicted analytically.
Biomaterials are a new treatment strategy for cardiovascular diseases but are difficult to deliver to the heart in a safe, precise, and translatable way. We developed a method to deliver hydrogels to the epicardium through the pericardial space. Our device creates a temporary compartment for hydrogel delivery and gelation using anatomic structures. The method minimizes risk to patients from embolization, thrombotic occlusion, and arrhythmia. In pigs there were no clinically relevant acute or subacute adverse effects from pericardial hydrogel delivery, making this a translatable strategy to deliver biomaterials to the heart.
Increased left ventricular (LV) stimulus intensity has been shown to improve conduction velocity and cardiac output. However, high-output pacing would shorten device battery life. Our prospective trial analyzed the clinical effects of high- versus low-output LV pacing. Thirty-nine patients undergoing initial cardiac resynchronization therapy device implantation with bipolar LV leads were assigned to 3 months of either high-output LV pacing (Hi) or low-output LV pacing (Lo) in a randomized, blinded crossover fashion. Hi and Lo settings were determined with a rigorous intraoperative protocol specific to each patient. Clinical and echocardiographic data were obtained at randomization, at 3 months, and a subsequent 3 months after crossover. Mean age was 66.4±9.8 years, and mean QRS duration was 159.3±23.1 ms. Compared to baseline, both arms had significant improvements in Minnesota Living With Heart Failure score (given as mean [95% confidence interval] ) (baseline versus Lo: 43.3 [35.5 to 51.1] versus 21.3 [14.6 to 28.0] , P < 0.01; baseline versus Hi: 43.3 [35.5 to 51.1] versus 23.6 [16.1 to 31.1] , P < 0.01) and 6-minute walk distance (baseline versus Lo: 692 ft [581 to 804] versus 995 ft [876 to 1114] , P < 0.01; baseline versus Hi: 699 ft [585 to 813] versus 982 ft [857 to 1106] , P < 0.01). Although both Hi and Lo arms had some echocardiographic parameters that significantly improved compared to baseline (baseline end-diastolic diameter 5.7 cm [5.5 to 6.0] versus Lo 5.5 cm [5.1 to 5.8] , P < 0.01; baseline end-systolic diameter 4.9 cm [4.6 to 5.3] versus Hi 4.7 cm [4.3 to 5.0] , P < 0.05), there were no significant differences observed when comparing the Hi- versus Lo-output arms. Low-output LV pacing with a relatively narrow safety margin above capture threshold affords significant improvement from baseline and is clinically equivalent to high-output LV pacing. These data support a strategy of minimizing the programmed LV safety margin to increase battery life in cardiac resynchronization therapy devices. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01060449.
Background
Psychological responses have been reported for some patients after insertion of an implantable cardioverter defibrillator (ICD). This study tested the effects of a psychoeducational intervention on anxiety, depressive symptoms, functional status and health resource use during the first year after ICD implantation.
Methods
ICD patients (n=246) were randomized to usual care (UC), group (GRP), or telephone counseling (TC) intervention that included education, symptom management, and coping skill training. Participants were 58 ± 11 years, 73% men, and 23% minorities. Anxiety (STAI), depressive symptoms (BDI-II), and functional status (DASI) were measured at baseline and after 1, 3, 6 & 12 months. Health resource use and disability days were tracked. Analyses were repeated-measures ANCOVA to assess Group X Time effects, Chi-square for percentage with clinically significant anxiety and depression at each time point, and logistic regression.
Results
All groups experienced decreased anxiety and depressive symptoms over the 12 months; GRP intervention had lower STAI (p=.03) than UC at 3 months. Logistic regression revealed group differences for predicted probability of having depressive symptoms at 12 months (UC=.31, GRP=.17, TC=.13, p=.03). UC had greater calls to providers at 1 and 6 months (p<.05) and more sick/disability days at 12 months (p=.01) than intervention groups.
Conclusions
A psychoeducational intervention reduced anxiety and depressive symptoms early after ICD, lowered probability of depressive symptoms at one year, and decreased disability days/calls to providers. These findings support further study and clinical use of both group and telephone interventions to yield better psychological outcomes after ICD implant.
Diagnosis and localization of cardiac arrhythmias, especially supraventricular tachycardia (SVT), by inspecting intracardiac signals and performing pacing maneuvers is the core of electrophysiology studies. Acquiring and maintaining complex skill sets can be facilitated by using simulators, allowing the operator to practice in a safe and controlled setting. An electrophysiology simulator should not only display arrhythmias but it has to respond to the user's arbitrary inputs. While, in principle, it is possible to model the heart using a detailed anatomical and cellular model, such a system would be unduly complex and computationally intensive. In this paper, we describe a freely available web-based electrophysiology simulator (http://svtsim.com), which is composed of a visualization/interface unit and a heart model based on a dynamical network. In the network, nodes represent the points of interest, such as the sinus and the atrioventric-ular nodes, and links model the conduction system and pathways. The dynamics are encoded explicitly in the state machines attached to the nodes and links. Simulated in-tracardiac signals and surface ECGs are generated from the internal state of the heart model. Reentrant tachycardias, especially various forms of SVT, can emerge in this system in response to the user's actions in the form of pacing maneuvers. Additionally, the resulting arrhythmias respond realistically to various inputs, such as overdrive pacing and delivery of extra stimuli, cardioversion, ablation, and infusion of medications. For nearly a decade, svtsim.com has been used successfully to train electrophysiology practitioners in many institutions. We will present our experience regarding best practices in designing and using electrophysiology simulators for training and testing. We will also discuss the current trends in clinical cardiac electrophysiology and the anticipated next generation electrophysiology simulators.
Background: The utility of standard distal bipolar electrograms (sEGMs) for assessing catheter-tissue contact may be obscured by the presence of far-field signals. Microelectrode electrograms (mEGMs) may overcome this limitation. Methods: We compared 5 mEGM characteristics (amplitude, frequency content, temporal signal variability, presence of injury current, and amplitude differential between bipoles) with the sEGM for determining tissue contact in 20 patients undergoing ablation of typical atrial flutter. Visualization of catheter-tissue contact by intracardiac echocardiography (ICE) served as the gold standard for assessing contact. Correlation between electrograms and ICE-verified contact level was reported as percent concordance. Results: Three of 5 mEGM characteristics demonstrated significantly better concordance with ICE-verified contact level than the sEGM (52% concordance with ICE): mEGM frequency content (59% concordance with ICE, P < .001 for comparison with sEGM); mEGM amplitude (concordance 59%, P < .001); and mEGM presence of injury current (56% concordance, P = .001). Concordance of amplitude differential between mEGM bipoles with ICE (49%) was not significantly different than the sEGM (P = .638) whereas mEGM temporal variability (39%) was significantly worse than the sEGM. Using a median of all 5 mEGM characteristics provided additive information (concordance with ICE 64%) and was significantly better than all of the individual mEGM characteristics except frequency content (P = .976). Conclusion: Microelectrode EGMs (in particular frequency content, amplitude, and presence of injury current) can improve real-time assessment of catheter contact compared to the use of standard bipolar EGMs. Broader use of mEGMs may enhance ablation efficacy.
Atrial fibrillation (AF) is an independent predictor of mortality after acute myocardial infarction (AMI). We analyzed the relation between biomarkers linked to myocardial stretch (NT-pro-brain natriuretic peptide [NT-proBNP]), myocardial damage (Troponin-T [TnT]), and inflammation (high-sensitivity C-reactive protein [hs-CRP]) and new-onset AF during AMI to identify patients at high risk for AF. In a prospective multicenter registry of AMI patients (from the Translational Research Investigating Underlying disparities in recovery from acute Myocardial infarction: Patients' Health status registry), we measured NT-proBNP, TnT, and hs-CRP in patients without a history of AF (n = 2,370). New-onset AF was defined as AF that occurred during the index hospitalization. Hierarchical multivariate logistic regression models were used to determine the association of biomarkers with new-onset AF, after adjusting for other covariates. New-onset AF was documented in 114 patients with AMI (4.8%; mean age 58 years; 32% women). For each twofold increase in NT-proBNP, there was an 18% increase in the rate of AF (odds ratio [OR] 1.18, 95% confidence interval [CI] 1.03 to 1.35; p <0.02). Similarly, for every twofold increase in hs-CRP, there was a 15% increase in the rate of AF (OR 1.15, 95% CI 1.02 to 1.30; p = 0.02). TnT was not independently associated with new-onset AF (OR 0.96, 95% CI 0.85 to 1.07; p = 0.3). NT-proBNP and hs-CRP were independently associated with new in-hospital AF after MI, in both men and women, irrespective of race. Our study suggests that markers of myocardial stretch and inflammation, but not the amount of myocardial necrosis, are important determinants of AF in the setting of AMI.