METHODS AND RESULTS The present study compares 120-lead body surface potential map (BSPM) data from 131 patients with acute MI and 159 normal control subjects (N). The MI population was stratified according to the location of ventricular wall motion abnormalities evidenced by radionuclide imaging into 76 patients with anterior MI (AMI), 32 patients with inferior MI (IMI), and 23 patients with posterior MI (PMI). BSPM were recorded within 24 hours of admission. Group mean BSPM of the ST segment were obtained for N, AMI, IMI, and PMI by sampling the time-normalized ST-T waveform at 18 equal intervals and averaging the voltages at each electrode site over the first five of these 18 ST-T time instants. Corresponding discriminant maps were also computed for each pairwise comparison (AMI versus N, IMI versus N, and PMI versus N) by subtracting the normal group mean voltages from each MI group mean voltages and by further dividing each resulting difference by the composite standard deviation calculated ...
Non-invasive diagnosis of acute myocardial infarction (AMI) associated with significant left main coronary artery stenosis (LMCAS) is challenging, with characteristic 12-lead ECG abnormalities of ST elevation (STE) in lead aVR, precordial T wave inversion (TWI) and/or ST depression (STD) having low diagnostic sensitivity. Methods Consecutive patients presenting to our unit with acute ischaemic-type chest pain from 2000-10 were analyzed. Entry criteria: 12-lead ECG and BSPM at presentation, cardiac troponin T (cTnT) ≤ 12h and coronary angiography during admission. Peak cTnT ≥0.03µg/L defined AMI. ECG abnormalities assessed: STEMI by Minnesota criteria; STE in lead aVR ≥0.5mm; STD ≥0.5mm in ≥2 contiguous leads (CL); TWI ≥1mm in ≥2CL. BSPM STE was: ≥2mm in anterior; ≥1mm in lateral, inferior, right ventricular (RV) or high right anterior (HRA); and ≥0.5mm in posterior territories. Angiographic luminal narrowing ≥70% defined significant LMCAS. Results Enrolled were 2810 ...
Adolescent; Adult; Arrhythmias, Cardiac; Body Surface Potential Mapping; Catheter Ablation; Child; Child, Preschool; District of Columbia; Female; Fluoroscopy; Humans; Infant; Infant, Newborn; Male; Prevalence; Radiation Dosage; Radiation Exposure; Radiation Protection; Retrospective Studies; Risk Factors; Surgery, Computer-Assisted; Treatment Outcome; Young Adult. ...
Ischemic heart disease is the single most frequent cause of death in. the world today. Electrocardiogram (ECG) exercise testing is a common. tool for diagnosing this disease. With the ECG exercise test one can. compare the recording of the electrical activity in the heart during. exercise and rest. A shift between the rest and exercise recording in. the segment of the heartbeat called the ST segment is used both for. diagnosing ischemia, and as input to cardiac computation methods.. Body surface potential mappings (BSPM) are ECG recordings at a greater. number of locations on the torso, and provides better detection and. localisation properties than the traditional 12-lead ECG. In BSPM and ECG,. noise and drift from various sources are recorded in addition to the. signal propagating from the heart. A model for this is:. BSPM=signal+noise+drift.. Before accurate measurements of the ST segments in a BSPM. can be made, the noise and drift in the recording must be reduced. while keeping the signal ...
Quantitatively mapping surface properties with nanometer or even subnanometer resolutions is critical for advanced scanning probe microscopy (SPM) characterization. However, the characterization performance often suffers from noises and artifacts due to instrumentation or environmental limitations. In this p
Objectives. This study examined the performance of the 62-lead body surface electrocardiogram (ECG) in identifying the site of origin of ventricular tachycardia in patients with a previous myocardial infarction.. Background. Because the accuracy of ECG localization of ventricular tachycardia using standard 12-lead recordings is restricted to the identification of rather large ventricular areas, application of multiple torso lead recordings may augment the resolving power of the surface ECG and result in more discrete localization of arrhythmogenic foci.. Methods. Thirty-two patients were selected for electrophysiologically guided ablative therapy for drug-resistant postinfarction ventricular tachycardia. In these patients, QRS integral maps of distinct monomorphic ventricular tachycardia configurations were correlated with a previously generated infarct-specific reference data base of paced QRS integral maps. Each paced pattern in the data base corresponded with ectopic endocardial impulse ...
The non-invasive localization of focal heart activity via body surface potential measurements (BSPM) could greatly benefit the understanding and treatment of arrhythmic heart diseases. However, the in vivo validation of source localization algorithms
BACKGROUND AND PURPOSE: Understanding drug effects on the heart is key to safety pharmacology assessment and anti-arrhythmic therapy development. Here our goal is to demonstrate the ability of computational models to simulate the effect of drug action on the electrical activity of the heart, at the level of the ion-channel, cell, heart and ECG body surface potential. EXPERIMENTAL APPROACH: We use the state-of-the-art mathematical models governing the electrical activity of the heart. A drug model is introduced using an ion channel conductance block for the hERG and fast sodium channels, depending on the IC(50) value and the drug dose. We simulate the ECG measurements at the body surface and compare biomarkers under different drug actions. KEY RESULTS: Introducing a 50% hERG-channel current block results in 8% prolongation of the APD(90) and 6% QT interval prolongation, hERG block does not affect the QRS interval. Introducing 50% fast sodium current block prolongs the QRS and the QT intervals by 12% and
To evaluate the source of ST depression, a sheep model of subendocardial ischaemia using partial coronary artery ligation coupled with atrial pacing was developed. Ischaemia was induced initially in either the left anterior descending coronary artery or the left circumflex coronary artery territory and subsequently in the territory of the other vessel. The ischaemic regions were documented by a fluorescent microsphere technique. During ischaemia potentials were mapped simultaneously from the endocardium and the epicardium. The distributions of epicardial potentials from either ischaemic source were very similar (0.77±0.14, P,0.0001), both showing ST depression on the free wall of the left ventricle, and no association between the ST depression and the ischaemic region. At the same time, the endocardial ST elevation was directly associated with the region of reduced blood flow. Insulating the heart from the surrounding tissue with plastic increased the magnitude of epicardial and endocardial ST ...
Optical potential energy landscapes created using acousto-optical deflectors are characterized via solvent-driven colloidal particles. The full potential energy of both single optical traps and complex landscapes composed of multiple overlapping traps are determined using a simple force balance argument. The potential of a single trap is shown to be well described by a Gaussian trap with stiffness found to be consistent with those obtained by a thermal equilibrium method. We also obtain directly the depth of the well, which (as with stiffness) varies with laser power. Finally, various complex systems ranging from double-well potentials to random landscapes are generated from individually controlled optical traps. Predictions of these landscapes as a sum of single Gaussian wells are shown to be a good description of experimental results, offering the potential for fully controlled design of optical landscapes, constructed from single optical traps.. © 2012 Optical Society of America. Full ...
One of the problems with applying these data clinically might be the extra-invasive procedure (insertion of the non-contact balloon to the left ventricle) and the subsequent time and cost. Theoretically it would be very useful to perform non-contact mapping during the implant procedure in order to identify the area of latest activation not obstructed by conduction block and scar. This would also allow the operator to pass the catheter locator signal produced by the non-contact mapping system through the left ventricular lead and therefore steer it to that site. However, at the present time it is recommended that the patient is heavily anticoagulated while the non-contact balloon is in the left heart which would prevent safe implantation of the CRT system.. Fung and colleagues14 have gone some way to try and overcome this problem by comparing non-contact mapping data to tissue Doppler imaging. They found that latest activation on non-contact and tissue Doppler correlated well. They did not ...
A surface mapping electrode set assembly is provided which includes a plurality of insulated, elongated wires, each of which terminates at a distal end head portion of the assembly. The electrodes of
Rapid atrial arrhythmias such as atrial fibrillation (AF) predispose to ventricular arrhythmias, sudden cardiac death and stroke. Identifying the origin of atrial ectopic activity from the electrocardiogram (ECG) can help to diagnose the early onset of AF in a cost-effective manner. The complex and rapid atrial electrical activity during AF makes it difficult to obtain detailed information on atrial activation using the standard 12-lead ECG alone. Compared to conventional 12-lead ECG, more detailed ECG lead configurations may provide further information about spatio-temporal dynamics of the body surface potential (BSP) during atrial excitation. We apply a recently developed 3D human atrial model to simulate electrical activity during normal sinus rhythm and ectopic pacing. The atrial model is placed into a newly developed torso model which considers the presence of the lungs, liver and spinal cord. A boundary element method is used to compute the BSP resulting from atrial excitation. Elements of ...
Pyloric motor neurons synapse at multiple sites along pyloric muscle fibers (Atwood et al., 1977, 1978; Atwood and Wojtowicz, 1986).A priori, two explanations for the EJP amplitude variability reported here thus exist. One is that the muscle fibers are essentially isopotential (fiber length less than two length constants) and the variability arises from variability in vesicle number released at each synaptic site during each spike. Given the large number of synaptic sites and large variation in quantal number observed at some crustacean synapses (Atwood and Wojtowicz, 1986), this variation would give rise to the smooth variation in EJP amplitude we observe. However, the short λ measured with multiple penetrations contradicts this explanation, because these data imply that the muscle fiber is not isopotential, and hence different synaptic sites are electrically isolated from each other. Pyloric muscle diameter is such that relatively small changes in membrane resistance would induce large length ...
We present a new image integration technique for flash and long-exposure image pairs to capture a dark scene without incurring blurring or noisy artifacts. Most existing methods require well-aligned images for the integration, which is often a burdensome restriction for practical use. We address this issue by locally transferring the colors of the flash images using a small fraction of corresponding pixels in the long-exposure images. We formulate image integration as a convex optimization problem with the local linear model. The proposed method makes it possible to integrate the color of the long-exposure image with the detail of the flash image without causing any harmful effects to its contrast, where the images do not need perfect alignment by virtue of our new integration principle. We show our method successfully outperforms the state-of-the-art in image integration and reference based color transfer for challenging misaligned datasets. ...
An implantable lead body, and method of manufacturing same, and system for stimulation. The lead body includes an expanding/expansion section providing an additional length or slack in the lead body and allowing the lead body to expand or stretch with the body thereby reducing or eliminating the mechanical force or strain on the ends of the lead at the destination sites.
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Air temperature: -2.2°C. In the late evening, the ship left iceberg C-18A and traveled east in search of an area away from the influence of icebergs. The principal investigators monitored the ships data systems during the transit to select the study area. When the ship reached a suitable location about 75 kilometers away, a suite of sampling began to characterize the area. First, the MOCNESS net system was deployed for several hours and recovered before sunrise. While the MOCNESS crew sorted samples in the lab, other research teams conducted water collections with trace-metal-clean Niskin bottles, surface mapping, and CTD casts throughout the day. Just after dinner, a Langrangian sediment trap was lowered into the water and started on a three-day drift at 600 meters depth. After completing the last set of surface mapping measurements late tonight, the ship will transit south back toward a zone rich with small icebergs for the next study area.. Bottles and bottles of seawater samples were ...
A lead assembly adapted for endocardial fixation to a human heart is provided. The lead assembly includes a lead body that has a proximal end provided with a connector for electrical connection to a cardiac stimulator. The cardiac stimulator may be a pacemaker, a cardioverter/defibrillator, or a sensing instrument. The distal end of the lead body is connected to a tubular electrode housing. The lead body consists of a noncoiled conductor cable surrounded by a coextensive insulating sleeve. In contrast to conventional leads, the lead body of the present invention does not require coiled conductor wires or an internal lumen. Manipulation of the lead body is via an external guide tube. Lead body diameters of 0.25 mm or smaller are possible.
Surface mapping plays an important role in geometric processing, which induces both area and angular distortions. If the angular distortion is bounded, the mapping is called a quasiconformal mapping (
Gene therapy to repair damaged heart muscle is most likely to succeed if it can be injected at the site of ischemia where there is viable myocardium with reduced contractile ability, and a new technique that combines imaging and electroanatomical mapping does just that. A study of this novel approach that shows increased blood flow in treated areas in patients with refractory angina is published in Human Gene Therapy.
A lead includes a lead body extending from a proximal end to a distal end and having an intermediate portion. A shocking electrode is disposed proximate the distal end of the lead body, and a pacing electrode is disposed along the intermediate portion of the lead body. The distal end of the lead body includes a preformed biased shape.
Start at 2018-01-19 12:35:36 First, load the ontology MsigdbC2KEGG and its gene associations in the genome Hs (2018-01-19 12:35:36) ... org.Hs.eg (from https://github.com/hfang-bristol/RDataCentre/blob/master/dnet/1.0.7/org.Hs.eg.RData?raw=true) has been loaded into the working environment (at 2018-01-19 12:35:37) org.Hs.egMsigdbC2KEGG (from https://github.com/hfang-bristol/RDataCentre/blob/master/dnet/1.0.7/org.Hs.egMsigdbC2KEGG.RData?raw=true) has been loaded into the working environment (at 2018-01-19 12:35:39) Then, do mapping based on symbol (2018-01-19 12:35:39) ... Among 19420 symbols of input data, there are 19038 mappable via official gene symbols but 382 left unmappable Third, perform GSEA analysis based on 1000 permutations for 186 gene sets (2018-01-19 12:35:43) ... Sample 1 is being processed at (2018-01-19 12:35:43) ... 10 of 186 gene sets have been processed (2018-01-19 12:35:45) ... 20 of 186 gene sets have been processed (2018-01-19 12:35:48) ... 30 of 186 gene sets have ...
Service Mapping can perform discovery based on data collected using the Netflow protocol. Netflow is a protocol that Service Mapping can use to collect data about CIs and their connections along with Netstat and lsof commands. Using the Netflow protocol
不動産担保ローンは無担保のローンに比べ金利が安い - 所有している不動産を担保にして借り入れをする不動産担保ローンは 無担保のローンに比べると 不動産の価値にもよりますが 金利が安く 融資額が大きい 長期の借り入れが可能などのメリットがあります》 融資額の内容は所有している […] ...
Pseudoaneurysm of thoracic aorta as a complication of blunt trauma to the chest, can present with a variety of symptoms due to mass compression effect. Here we report the first pseudoaneurysm of thoracic aorta presenting with chronic cough and inappropriate sinus tachycardia. The purpose of this case report is to highlight pseudoaneurysm of thoracic aorta as a rare differential diagnosis for inappropriate sinus tachycardia. Here we report a case of 29-year-old white woman, a nurse, with history of a motor vehicle accident. She initially presented to medical attention with inappropriate sinus tachycardia 2 years following the motor vehicle accident during her pregnancy. Six years later she underwent sinoatrial node modification after failing a number of medications. Days prior to the ablation she developed a mild cough which became constant within a week following ablation. A computed tomography scan of her chest performed as part of a workup revealed an outpouching of the inferomedial aspect of the
Optical tweezers (OT) are widely used for pico (and femto)-Newton range force measurements. The appropriate choice of the bead size is not well understood for biopolymer stretching applications of OT. We have shown, both by theory and experiment, that wrong choice of the bead size could cause errors as large as 295% in the measured force. We provide a simple map for correct choice of the bead size and the direction of pulling for such applications. There is a good agreement between our theoretical and experimental results.. © 2013 Optical Society of America. Full Article , PDF Article ...
Inappropriate sinus tachycardia (IST) is a non-paroxysmal arrhythmia, characterized by a persistently high sinus heart rate (HR) and/or an exaggerated HR response to minimal exertion, and can be responsible for palpitations, asthenia, chest pain, dizziness and syncope, which can be highly invalidating. Conventional treatment of IST, targeted to symptoms control, mainly consists on β-blockers. However, these drugs are often insufficient or not well tolerated because of side effects (mostly hypotension) that usually limit the administered dose. Ivabradine, a sinus rate lowering agent currently employed in Europe in the treatment of stable angina and chronic heart failure, has recently been demonstrated to be effective and safe in the treatment of IST by a few case reports and clinical trials. A randomized clinical trial comparing ivabradine to β-blockers has not be performed yet ...
Can inappropriate sinus tachycardia be brought on by having severe gastroparesis and chronic fatigue? I was just diagnose with IST and doc thinks it was brought on by my severe illness and he said that...
0154] FIG. 20 is an illustration of an exemplary application of functional imaging and non-invasive electrical potential mapping according to a method of the present invention. As will be appreciated, the system and methodology of the present invention allow for both functional imaging of biological objects 19 and mapping of electrical excitation within biological tissues 19. This may be achieved as a two-step imaging process, as illustrated in FIG. 20. First, the system 100 is used as an electromagnetic tomographic imaging tool for non-invasive assessment of functional and pathological conditions of a biological object 19 and the location of any areas of diseased tissues 19. For example, in FIG. 20, cardiac tissue with suspicious areas of myocardium is functionally imaged in Step 1 to identify areas of ischemia/infarction. Second, if the location of a diseased target is within a biologically excited tissue 19 (such as cardiac tissue, nervous tissue, musculoskeletal tissue, or the like), then a ...
The techniques of theoretical chemistry have been used to elucidate the molecular properties and modes of receptor binding that modulate receptor affinity and antagonist activity of the beta-carbolines, a class of potent benzodiazepine antagonists. Six analogs were chosen in order to investigate the role of the amine (NH) group, the aromatic nitrogen, and the C3-substituent in determining receptor affinities. Electrostatic potential mapping and characterization of explicit drug-receptor interactions have led to the hypothesis that simultaneous interaction of a model cationic arginine site with the N2 and C3-substituents could play a key role in determining receptor affinities. The electron-withdrawing effects of C3-substituents on the amine nitrogen appear less important, though interactions of these groups with an anionic glutamate or aspartate site could also occur at the receptor. Similarly, stacking interactions with neutral or cationic aromatic residues such as tryptophan or protonated ...
Since I was 18, I have noticed times when my heart seems to stall out for a second or so, then catch up by beating really rapidly for a few beats before evening itself out. Since these occure...
Hi everyone. I am new to this group and was really hoping that someone might have some insight for me. Im a 23 year old female and have been diagnosed with IST...
The mechanism of post-infarct SMVT is scar-related re-entry in the majority of patients (1). Inhomogeneous scarring with varying degrees of subendocardial myocardial fiber preservation within dense zones of fibrosis leads to slowed conduction, nonuniform anisotropy, and the potential for channels within the scar zone-conditions necessary for the development of re-entry (2,3). In the ablation era, high-density electroanatomic mapping has been used to characterize the electrical correlates of this well-described pathologic substrate, allowing for development of substrate modification strategies (7) to target unmappable SMVTs (19). Channels within a scar (isolated potentials [6,11], very late potentials) or regions at the scar-border zone (putative exit sites) (18,20) appear to represent critical components of the re-entrant circuit and have all been targeted with successful long-term ablation outcomes.. The current study compares these key markers of SMVT substrate by creating high-density maps of ...
A medical lead which has a connector assembly coupled to an electrode by a lead body, the lead body is designed so as to have greater resistance to crush fatigue in the area which is located between the rib and clavicle when implanted. In particular the lead body of the present invention features an insulative sheath covering a coiled conductor. The coiled conductor has three sections, viz., proximal, intermediate and distal sections. The intermediate section has a different pitch as compared to proximal section and distal section. In the preferred embodiment, intermediate section has a pitch of approximately 0.100 while proximal section has a pitch of approximately 0.025 and distal section has a pitch of approximately 0.025. Moreover, intermediate section has a length of approximately 10.4 inches while proximal section has a length of approximately 5.1 inches and distal section has a length of approximately 7.2 inches. In such a manner the lead of the present invention presents a coiled conductor
An assembly is provided for an implantable medical lead. The assembly includes a first lead body comprising one or more electrical leads, and a hermetic encasement. The encasement comprises a housing having first and second openings and interior walls, an interior space defined by the interior walls, an electronic network housed within the interior space, and a circuit board extending through the first and second openings. The circuit board comprises a plurality of layers into which the electronic network is at least partially integrated, a first set of one or more terminals electrically coupling the electronic network to the first lead body, and a second set of one or more terminals electrically coupled to the electronic network for external electrical engagement.
Hi everyone. I havent posted in a very long time, but I experienced HELLP with my pregnancy back in November of 2010. Since then there have been several tests for autoimmune disorders and other things, all which have come back normal. However, I have had fairly frequent heart palpitations since the birth of my son. I actually got them prior to my pregnancy, but they would be very rare...now they occur more frequently. After wearing a heart monitor, it looks like I am basically experiencing inappropriate sinus tachycardia. This isnt a very serious thing from what I gather, but I am on a low dose beta-blocker to help with the symptoms ...
Assessment of myocardial fibrosis by endoventricular electromechanical mapping in experimental nonischemic cardiomyopathy.. International Journal of Cardiovascular Imaging International Journal of Cardiac Imaging. 27:25-37. 2011 ...
A lead includes a lead body extending from a proximal end to a distal end and having an intermediate portion. A shocking electrode is disposed proximate the distal end of the lead body, and a pacing electrode is disposed along the intermediate portion of the lead body. The distal end of the lead body includes a pre-formed biased shape.
To demonstrate this potential, clusters of contracting cardiomyocytes isolated from the differentiation cultures were transplanted into the left ventricle of pigs that had their atrioventricular node ablated. The recipient hearts had spontaneous rhythms that appeared to originate from the transplanted cells as assessed by high-resolution electroanatomical mapping. Though promising, these results also raise the concern that transplanted cells could serve as a nidus for arrhythmia. Other mesoderm-derived lineages. While the hematopoietic, vascular, and cardiac lineages have been studied in most detail, the ES cell system does offer the potential to develop many other mesoderm lineages. To date, cell populations representing the skeletal muscle (Rohwedel et al. 1994 ...
The Seal of Danthazars about to open for-real cross-my-heart this time, so stand back. The seal - basically a manhole with modified Sigil of Baphomet and some vaguely Celtic knots - isnt literally over the Hellmouth. The Hellmouth is a colorful term for the focal point of mystical energies. In other circumstances, that might read as fantasy gobbledy-gook to smear over any number of sins in plotting mechanics. Lately, down at the convergence point in the basement, the floor plan has become unmappable, shifting, nonlinear. Tricky. And the Hellmouth is nowhere, but does seem to end up manifesting as a hole in the dirt which belches forth unclean things. And the Hellmouth is everywhere, but seems to draw all dramatic focus to the sepulchral caverns under a school. This spot seems to want to be a school or need to be a school. If you burn it down, the Hellmouth pushes a new one up through the rubble. If you switch campuses to UC Sunnydale, youll find the Hellmouths manmade twin malfunctioning ...
The Seal of Danthazars about to open for-real cross-my-heart this time, so stand back. The seal - basically a manhole with modified Sigil of Baphomet and some vaguely Celtic knots - isnt literally over the Hellmouth. The Hellmouth is a colorful term for the focal point of mystical energies. In other circumstances, that might read as fantasy gobbledy-gook to smear over any number of sins in plotting mechanics. Lately, down at the convergence point in the basement, the floor plan has become unmappable, shifting, nonlinear. Tricky. And the Hellmouth is nowhere, but does seem to end up manifesting as a hole in the dirt which belches forth unclean things. And the Hellmouth is everywhere, but seems to draw all dramatic focus to the sepulchral caverns under a school. This spot seems to want to be a school or need to be a school. If you burn it down, the Hellmouth pushes a new one up through the rubble. If you switch campuses to UC Sunnydale, youll find the Hellmouths manmade twin malfunctioning ...
A lead includes a lead body extending from a distal end to a proximal end, and at least one conductor disposed within the lead body and extending from the distal end to the proximal end of the lead body. The lead further includes an outer terminal ring, a terminal pin, and an insulative sleeve disposed between the outer terminal ring and the terminal pin, where the insulative sleeve is coupled with the outer terminal ring with a snap-fit connection. A pin latch is disposed on an outer periphery surface of the insulative sleeve, where the pin latch is rotatable about a hinge point.
Having received the European CE Mark for its Rhythmia Mapping System just last May, Boston Scientific just won FDA clearance for the cardiac mapping and
Cardiac mapping is a technique in which the information from cardiac electrograms is gathered and displayed. Cardiac mapping is used to diagnose the heart
Technological singularity around the corner? » Forum Post by Timmaigh » Is this actually for real? I mean do they really h
This meta-analysis is limited by the studies included in the analysis. All of the studies were observational studies, and therefore they are susceptible to selection bias. There were significant differences in the patients included and the strategy used when performing VT ablations. Although the overall strategy was to target all inducible VTs, only 1 study indicated ablation of all clinically relevant VTs as a predetermined end point.23 Table II in the Data Supplement indicates the specific protocols and catheters used in the analyzed studies.. Another important limitation is the definition of the clinical VT. The definition used in the selected studies is not uniform and is not based on the 12-lead ECG in all studies. Because 12-lead ECGs are not available for all patients, VT electrogram morphology from implantable cardioverter defibrillators can be used instead with similar accuracy and have been found to be helpful in identifying the clinical VT.5 This definition was used by only one, but ...
Electrostatic potential maps (EPMs) allow for representation of key molecular-level information in a relatively simple and inexpensive format. As these visualizations become more prevalent in instruction, it is important to determine how students are exposed to them and supported in their use. A systematic review of current general and organic chemistry textbooks (N = 45) determined how frequently EPMs were presented in texts, how well distributed EPMs were across chapters, whether EPMs were included in end-of-chapter problems, and the types of conceptual instructional support provided to students when first exposed to them. Analysis demonstrated great variance in the use of EPMs. Most, but not all, textbooks presented at least one image, yet the prevalence and integration across texts varied greatly, owing in part to content differences between general and organic texts. Many texts provided minimal conceptual support and did not include EPMs in end-of-chapter problem sets. Overall,
Cardiac magnetic resonance imaging (MRI) is a highly accurate non-invasive method for assessing myocardial scar by delayed enhancement imaging. Attempts to correlate electrogram voltage characteristics obtained by catheter-based point mapping to scar detected by MRI suggest that conventional substrate mapping techniques have limitations that could hinder ablative efficacy. This chapter discusses the role of cardiac MRI in the substrate-based ablation of unstable, reentrant ventricular tachycardias prior to ablation, during ablation and after ablation. Prior to ablation, the presence of delayed enhancement and its patterns can provide clues about the potential for reentrant circuits and regions where substrate may be present. During ablation, the integration of MRI-based scar maps with voltage-based scar maps within electroanatomical mapping systems has an emerging role, and may help identify residual channels of conduction embedded within regions of heterogeneous scar. After ablation, ...
Methods and Results Nineteen patients with CC undergoing detailed epicardial and endocardial LV tachycardia mapping and ablation were included. A total of 8494 epicardial and 6331 endocardial voltage signals and 314 epicardial/endocardial matched pairs of points were analyzed. Basal lateral LV scar involvement was observed in 18 of 19 patients. Bipolar voltage mapping demonstrated larger epicardial than endocardial scar and core-dense (≤0.5 mV) scar areas (28 [20-36] versus 19 [15-26] and 21 [2-49] versus 4 [0-7] cm2; P=0.049 and P=0.004, respectively). Bipolar epicardial and endocardial voltages within scar were low (0.4 [0.2-0.55] and 0.54 [0.33-0.87] mV, respectively) and confluent, indicating a dense/transmural scarring process in CC. The endocardial unipolar voltage value (with a newly proposed ≤4-mV cutoff) predicted the presence and extent of epicardial bipolar scar (P,0.001). ...