Cardiac Beat Research Articles

An Unusual Case of Cyanosis in a Young Boy

Question: A 13-year-old boy presented with a 2.5-year history of dyspnea and fatigue and detected to have cyanosis over the past 6 months. He did not have any history of palpitations, syncope, cough, wheezing, or recurrent chest infections. He was the elder of 2 siblings, born out of a nonconsanguineous marriage with a normal, uncomplicated antenatal and perinatal history. His developmental history and performance at school were normal. His clinical examination revealed normal anthropometric parameters as per his age, cyanosis at rest, and grade III clubbing of fingers; the rest of his systemic examination including cardiovascular, pulmonary, neurologic, and abdominal examination was normal. Arterial blood gas analysis revealed type 1 respiratory failure, mild respiratory alkalosis, and severe hypoxemia (pH, 7.46; PO2 on room air, 49 mmHg; PCO2, 32.9 mmHg; HCO3, 23.1 mmol/L; SpO2, 88%). Chest xray was normal. Air contrast-enhanced transthoracic echocardiography revealed right-to-left shunting evident by the appearance of air bubbles in the left cardiac chambers about 3 cardiac beats after appearance in the right chambers but no structural cardiac defect or pulmonary hypertension. Compute tomographic angiography of the chest was normal and did not reveal any large pulmonary arteriovenous shunt. So with the possibility of multiple small intrapulmonary shunts he was further evaluated for any hepatoportal disease. Liver function tests and arterial plasma ammonia levels were normal; upper gastrointestinal endoscopy was normal. Doppler ultrasonography of the hepatoportal system (Figure A), contrast magnetic resonance imaging of the abdomen (Figure B, C) were done for further evaluation which revealed an abnormal vascular channel in the liver (arrow) and barely visible intrahepatic portal venous radicals (IHPVR; asterisk). What is the most likely diagnosis? See the GASTROENTEROLOGY web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI.

In vivo cardiac phase response curve elucidates human respiratory heart rate variability

Recovering interaction of endogenous rhythms from observations is challenging, especially if a mathematical model explaining the behaviour of the system is unknown. The decisive information for successful reconstruction of the dynamics is the sensitivity of an oscillator to external influences, which is quantified by its phase response curve. Here we present a technique that allows the extraction of the phase response curve from a non-invasive observation of a system consisting of two interacting oscillators--in this case heartbeat and respiration--in its natural environment and under free-running conditions. We use this method to obtain the phase-coupling functions describing cardiorespiratory interactions and the phase response curve of 17 healthy humans. We show for the first time the phase at which the cardiac beat is susceptible to respiratory drive and extract the respiratory-related component of heart rate variability. This non-invasive method for the determination of phase response curves of coupled oscillators may find application in many scientific disciplines.

Smart-phone based electrocardiogram wavelet decomposition and neural network classification

This paper discusses ECG classification after parametrizing the ECG waveforms in the wavelet domain. The aim of the work is to develop an accurate classification algorithm that can be used to diagnose cardiac beat abnormalities detected using a mobile platform such as smart-phones. Continuous time recurrent neural network classifiers are considered for this task. Records from the European ST-T Database are decomposed in the wavelet domain using discrete wavelet transform (DWT) filter banks and the resulting DWT coefficients are filtered and used as inputs for training the neural network classifier. Advantages of the proposed methodology are the reduced memory requirement for the signals which is of relevance to mobile applications as well as an improvement in the ability of the neural network in its generalization ability due to the more parsimonious representation of the signal to its inputs.

Multi-parameter in vitro toxicity testing of crizotinib, sunitinib, erlotinib, and nilotinib in human cardiomyocytes

Tyrosine kinase inhibitors (TKi) have greatly improved the treatment and prognosis of multiple cancer types. However, unexpected cardiotoxicity has arisen in a subset of patients treated with these agents that was not wholly predicted by pre-clinical testing, which centers around animal toxicity studies and inhibition of the human Ether-à-go-go-Related Gene (hERG) channel. Therefore, we sought to determine whether a multi-parameter test panel assessing the effect of drug treatment on cellular, molecular, and electrophysiological endpoints could accurately predict cardiotoxicity. We examined how 4 FDA-approved TKi agents impacted cell viability, apoptosis, reactive oxygen species (ROS) generation, metabolic status, impedance, and ion channel function in human cardiomyocytes. The 3 drugs clinically associated with severe cardiac adverse events (crizotinib, sunitinib, nilotinib) all proved to be cardiotoxic in our in vitro tests while the relatively cardiac-safe drug erlotinib showed only minor changes in cardiac cell health. Crizotinib, an ALK/MET inhibitor, led to increased ROS production, caspase activation, cholesterol accumulation, disruption in cardiac cell beat rate, and blockage of ion channels. The multi-targeted TKi sunitinib showed decreased cardiomyocyte viability, AMPK inhibition, increased lipid accumulation, disrupted beat pattern, and hERG block. Nilotinib, a second generation Bcr-Abl inhibitor, led to increased ROS generation, caspase activation, hERG block, and an arrhythmic beat pattern. Thus, each drug showed a unique toxicity profile that may reflect the multiple mechanisms leading to cardiotoxicity. This study demonstrates that a multi-parameter approach can provide a robust characterization of drug-induced cardiomyocyte damage that can be leveraged to improve drug safety during early phase development.

Giant Multiloculated Left Ventricular Outflow Tract Pseudoaneurysm Causing Severe Extrinsic Compression of Subpulmonic Infundibulum

A 14-year-old female presented to us with a history of palpitation and progressive dyspnoea for the last 2 months. She also had a history of prolonged fever 4-months back. On examination, she had a pulse rate of 110 bpm and a blood pressure of 110/60 mm Hg. Her precordial examination revealed a hyperdynamic and downwards displaced cardiac apex beat. The cardiac auscultation revealed a pansystolic murmur with thrill along the left parasternal border and an early diastolic murmur with ejection systolic murmur in the left 3rd intercostal space. The chest examination and systemic examination were normal. The chest radiograph (PA view) showed cardiomegaly (CT ratio 0.65) with prominence of main pulmonary artery segment (Figure 1A). The 12-channel ECG showed left ventricular hypertrophy with diastolic overload pattern (Figure 1B). Two-dimensional transthoracic echocardiography in parasternal long-axis view showed a high-velocity turbulent color jet arising below the aortic valve from the left ventricular outflow tract (LVOT) and going toward the right ventricular outflow tract (Figure 2A; Movie I in the online-only Data Supplement). In parasternal short-axis view, a large multi-loculated structure was seen, lying on the right side of the aorta and having extension toward the right ventricular outflow tract (Figure 2B; Movie II in the online-only Data Supplement). The color Doppler echocardiogram showed a turbulent jet …

Abstract 4423: Implications for cardiotoxicity with targeted therapies.

Abstract Tyrosine kinase inhibitors (TKi) have greatly improved the treatment and prognosis of multiple cancer types. However, unexpected cardiotoxicity has arisen that was not wholly predicted by current FDA mandated pre-clinical tests. Thus a more robust tool to predict the cardiotoxic potential of these compounds is warranted. For this purpose, we developed a panel of in vitro tests in a clinically relevant human cardiomyocyte model that assesses drug impact on overall cardiac health (cell viability, apoptosis, and morphology), mitochondria and metabolic intactness (reactive oxygen species (ROS) generation, AMPK activity, and lipid accumulation), and electrophysiological function (impedance (beat rate) and ion channel blockage). To demonstrate the utility of our panel, we examined the effect of 4 FDA-approved TKi with known clinical outcome on cardiac health. The 3 drugs with known cardiac adverse events (crizotinib, sunitinib, and nilotinib) all proved to be cardiotoxic by our panel although each showed distinct mechanisms of toxicity. However erlotinib, a cardiac-safe drug that targets EGFR and is used primarily in non-small cell lung cancer (NSCLC), did not show any indications of toxicity. Surprisingly, the most cardiotoxic drug by our panel was crizotinib, an ALK/ MET inhibitor that has revolutionized treatment for ALK+ NSCLC patients. Crizotinib potently impaired overall cardiac health by increasing ROS and apoptosis but also impeded electrophysiological function by inducing ion channel blockage and reducing cardiac beat rate. Interestingly crizotinib also induced lipid and cholesterol accumulation which was shown to be correlated with increased expression of the sterol-regulatory binding protein (SREBP) pathway by transcriptome analysis. The multi-targeted TKi sunitinib (used in renal cell carcinoma and gastrointestinal stromal tumors) and nilotinib (used in chronic myelogenous leukemia) also showed unique cardiotoxicity profiles. In conclusion, our studies showed a distinct cardiotoxicity profile for each TKi that correlates with clinical outcome. These results suggest that caution should be taken with these TKi especially when used long-term or in the adjuvant setting. Furthermore, these effects may be exacerbated in patients with adverse cardiac genetic predispositions and studies are ongoing in our lab on patient-derived cardiac cell lines to investigate this possibility. This multi-parameter screening approach allows for a more complete assessment of the potential for drug-induced cardiotoxicity and may allow for earlier detection in the drug development process. In addition, understanding the mechanisms of cardiac toxicities may lead to the discovery of novel mitigation strategies and combination therapies to improve cardiac cell health during treatment with oncology therapies. Citation Format: Kimberly R. Doherty, Robert L. Wappel, Dominique R. Talbert, Patricia B. Trusk, Scott A. Shell, Diarmuid M. Moran, James W. Kramer, Arthur Brown, Sarah Bacus. Implications for cardiotoxicity with targeted therapies. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4423. doi:10.1158/1538-7445.AM2013-4423

Cardiac variation of inferior vena cava: new concept in the evaluation of intravascular blood volume.

Evaluation of the intravascular blood volume is an important assessment in emergency and critical care medicine. Measurement of the inferior vena cava (IVC) respiratory variation by ultrasound echography is useful, but it entails subjective problems. We have hypothesized that IVC cardiac variation is also correlated with intravascular blood volume and analyzed it automatically using computer software of two kinds, later comparing the results. Snakes, software to track boundaries by curve line continuity, and template matching software were incorporated into a computer with an ultrasound machine to track the short-axis view of IVC automatically and analyze it with approximation by ellipse. Eight healthy volunteers with temporary mild hypovolemia underwent echography before and after passive leg raising and while wearing medical anti-shock trousers. IVC cardiac variation was visually decreased by both leg raising and medical anti-shock trousers. The collapse index (maximum-minimum/maximum) of area during three cardiac beats was decreased showing a good relationship to fluid load simulations; 0.24±0.03 at baseline versus 0.11±0.01 with leg raising and 0.12±0.01 with medical anti-shock trousers. In conclusion, IVC cardiac variation has the potential to provide an evaluation of water volume. It presents some advantages in mechanical analysis over respiratory variation. At the very least, we need to exercise some caution with cardiac variation when evaluating respiratory variation.

Change in myocardial oxygen consumption employing continuous-flow LVAD with cardiac beat synchronizing system, in acute ischemic heart failure models

Aiming the 'Bridge to Recovery' course, we have developed a novel left ventricular assist device (LVAD) controlling system. It can change the rotational speed of the continuous flow LVAD, EVAHEART, synchronized with the cardiac beat. Employing this system, we have already demonstrated that myocardial oxygen consumption (MVO2), which is considered to be equivalent to native heart load, changes in the hearts of normal goats. Herein, we examined changes in goats with acute ischemic heart failure. We studied 14 goats (56.1±6.9kg) with acute ischemic heart failure due to coronary microsphere embolization. We installed the EVAHEART and drive in four modes: "circuit-clamp", "continuous support", "counter-pulse", and "co-pulse", with 50 and 100% bypass. In comparison to the circuit-clamp mode, MVO2 was reduced to 70.4±17.9% in the counter-pulse mode and increased to 90.3±14.5% in the co-pulse mode, whereas it was 80.0±14.5% in the continuous mode, with 100% bypass (p<0.05). The same difference was confirmed with 50% bypass. This means that we may have a chance to change the native heart load by controlling the LVAD rotation in synchrony with the cardiac rhythm, so we named our controller as the Native Heart Load Control System (NHLCS). Employing changeable MVO2 with NHLCS according to the patient's condition may provide more opportunity for native heart recovery with LVAD, especially for patients with ischemic heart diseases.

Junior doctor skill in the art of physical examination: a retrospective study of the medical admission note over four decades

ObjectivesTo investigate the hypothesis that junior doctors’ examination skills are deteriorating by assessing the medical admission note examination record.DesignRetrospective study of the admission record.SettingTertiary care hospital.MethodsThe admission records of 266...

Change of Coronary Flow by Continuous-Flow Left Ventricular Assist Device With Cardiac Beat Synchronizing System (Native Heart Load Control System) in Acute Ischemic Heart Failure Model

A novel control system for the EVAHEART left ventricular assist device (LVAD), known as the Native Heart Load Control System (NHLCS), can change the device's rotational speed (RS) in synchrony with the heartbeat. The system enhanced coronary flow (CoF) with the counter-pulse mode in normal goats' hearts, so we examined the change in CoF in goats with acute ischemic heart failure (HF). We studied 14 goats (56.1±6.9kg) with acute ischemic HF induced by coronary microsphere embolization. We installed EVAHEART and ran the device in 4 modes [continuous support, circuit-clamp, counter-pulse (raise RS in diastole), and co-pulse (raise RS in systole)] with 50% or 100% bypass in each mode. In comparison with the circuit-clamp mode, CoF was 121.0±14.1% in the counter-pulse mode and 102.9±7.9% in the co-pulse mode, whereas it was 113.5±10.6% in the continuous mode, with 100% bypass (P<0.05). The same difference was confirmed with 50% bypass. The results indicated that a LVAD in an acute ischemic heart enhanced CoF, and that CoF was greater in the counter-pulse mode and smaller in the co-pulse mode relative to the continuous mode. By using NHLCS to change CoF, recovery of native heart function with a LVAD has a better prognosis.

Autonomic Response to Hypoxia and Isometric Exercise in Sickle Cell Trait Subjects

AbstractAbstract 3241Loss of cardiac beat to beat variability reflected by high frequency power (HFP) is a strong predictor of death in patients with cardiovascular disease. Similar autonomic dysfunction is found in patients with Sickle Cell Anemia (SCA) and can be induced by a 30 second period of hypoxia during five breath nitrogen exposure (1,2). Some data suggest that Sickle Cell Trait (SCT) carriers also exhibit autonomic dysfunction. In light of the recent attention to sudden death in young athletes with SCT we examined the autonomic response to transient hypoxia and isometric exercise in subjects with SCT and matched controls.Autonomic responses to hypoxia induced by a five-breath nitrogen exposure and intense isometric exercise resulting from handgrip to exhaustion were measured. Autonomic parasympathetic tone and sympathetic-vagal balance were measured using respiratory-adjusted time-varying heart rate variability (HRV). High frequency power (HFP) reflects parasympathetic tone and low-high ratio (LHR), sympathetic-vagal balance (1,2).Ten African American SCT carriers (7 female, 35.7 yrs + 2.8) and 11 age, and ethnicity matched controls (CTRL, 8 female, 30.5 yrs + 2.8) were studied. No difference in resting heart rate (HR, SCT 67.1 + 5.1, CTRL 65.9 + 5.5), cardiac output (CO, SCT 6.17 + .57, CTRL 7.31 + .52), mean arterial pressure (MAP, SCT 101.49 + 4.61, CTRL 101.49 + 4.96) or LHR (SCT, 1.16 + .38, SCT 1.44 + .37) was observed.Five-breath nitrogen exposure produced nearly identical minimal arterial saturation (SaO2, SCT 84.1% ± 1.3%, CTRL 83.1% ± 1.3%) with compensatory tachycardia (DRRI, SCT −6.5% ± 1.2%, CTRL −4.79 ± 1.15%) and increased cardiac output (DCO, SCT 4.7% ± 1.7, CTRL 6.0% ± 1.6%). No change from baseline was observed in the population means of HFP or LHR for CTRLs or SCT subjects.Following ten minutes of recovery, handgrip to exhaustion was performed at 60% maximum voluntary contraction. No differences were observed in maximum handgrip or duration between SCT and CTRL. Men produced higher maximal response but women maintained contraction nearly twice as long, independent of diagnosis. Handgrip exercise increased heart rate, cardiac output (SCT +13.4% ± 5.4%, CTRL +13.9% ± 5.0%), mean arterial pressure (SCT +19.6% ± 2.5%, CTRL +16.0% ± 2.3%), systolic pressure (SCT +14.6% ± 2.2%, CTRL +10.7% ± 2.1%), and diastolic pressure (SCT +22.5% ± 2.9%, CTRL +18.5% ± 2.6%). No population differences were observed in these responses. LHR increased similarly in both populations as well (SCT +78.9% ± 35.7%, CTRL +68.5% ± 32.9%), but SCT carriers had a much larger drop in HFP that was significantly different from baseline and trended lower than the control population (SCT −58% ± 18%, CTRL −9% ± 17%, p<.063).Our laboratory has previously demonstrated hyper-reflexic parasympathetic withdrawal in response to transient hypoxia in patients with SCA (1,2). SCT subjects did not demonstrate parasympathetic withdrawal to hypoxia. However, we found exaggerated parasympathetic withdrawal in response to handgrip exercise in SCT subject and not in matched controls. Even though the biophysical properties of the sickle trait red cell are not sufficient to result in major hemolysis or vaso-occlusion, they are sufficient to alter autonomic balance. It will be important to determine whether this response impacts the distribution of ventricular repolarization, potentially increasing risk of arrhythmia, or is reproduced in other autonomic axes such as mental stress. [Display omitted] [Display omitted] Disclosures:Coates:Apopharma: Consultancy; Novartis: Speakers Bureau. Wood:Novartis: Honoraria, Research Funding; Apotex: Consultancy, Honoraria; Shire: Consultancy; Ferrokin Biosciences: Consultancy.

Redox control of cardiac rhythm

The rhythm of cardiac beats is generated by pacemaker cells differing from other cardiomyocytes by the presence of slow diastolic depolarization. Consistently activated transmembrane ionic currents provide cyclic excitation of pacemakers, forming the original "membrane clocks". A new concept has been forwarded in the last decade according to which periodic fluctuations in myoplasmic Ca2+ level ("calcium clocks") not only influence a course of "membrane clocks", but they also can serve as independent generators of the rhythm. Transport of Ca2+ in cells is under constant influence of active forms of oxygen and nitrogen. Both superoxide and NO in moderate doses facilitate Ca2+ output from the sarcoplasmic reticulum, accelerating the course of "calcium clocks", but in higher doses they have opposite effect that may be neutralized mainly by reduced glutathione. The control of cardiac rhythm by active forms of oxygen and nitrogen represents a feedback mechanism by which mitochondria and NO-synthases support Ca2+ homeostasis in cells that can be temporarily disturbed under mechanical loads or hypoxia.

Short-term complexity indexes of heart period and systolic arterial pressure variabilities provide complementary information

It is unclear whether the complexity of the variability of the systolic arterial pressure (SAP) provides complementary information to that of the heart period (HP). The complexity of HP and SAP variabilities was assessed from short beat-to-beat recordings (i.e., 256 cardiac beats). The evaluation was made during a pharmacological protocol that induced vagal blockade with atropine or a sympathetic blockade (beta-adrenergic blockade with propranolol or central sympathetic blockade with clonidine) alone or in combination, during a graded head-up tilt, and in patients with Parkinson's disease (PD) without orthostatic hypotension undergoing orthostatic challenge. Complexity was quantified according to the mean square prediction error (MSPE) derived from univariate autoregressive (AR) and multivariate AR (MAR) models. We found that: 1) MSPE(MAR) did not provide additional information to that of MSPE(AR); 2) SAP variability was less complex than that of HP; 3) because HP complexity was reduced by either vagal blockade or vagal withdrawal induced by head-up tilt and was unaffected by beta-adrenergic blockade, HP was under vagal control; 4) because SAP complexity was increased by central sympathetic blockade and was unmodified by either vagal blockade or vagal withdrawal induced by head-up tilt, SAP was under sympathetic control; 5) SAP complexity was increased in patients with PD; and 6) during orthostatic challenge, the complexity of both HP and SAP variabilities in patients with PD remained high, thus indicating both vagal and sympathetic impairments. Complexity indexes derived from short HP and SAP beat-to-beat series provide complementary information and are helpful in detecting early autonomic dysfunction in patients with PD well before circulatory symptoms become noticeable.

Optimized Hyaluronic Acid–Hydrogel Design and Culture Conditions for Preservation of Mesenchymal Stem Cell Properties

A novel approach that preserved most mesenchymal stem cell (MSC) characteristics was developed using MSC encapsulation in a hydrogel based on hyaluronic acid (HA). An optimized HA-hydrogel composition, whose characteristics were assessed by scanning electron microscopy and viscoelastic property analyses, as well as the more favorable MSC seeding density, was established. These optimal three-dimensional MSC culture conditions allowed morphological cell remodeling, maintained the expression of stem cell markers over 28 days of culture, and preserved MSC differentiation plasticity. In addition, MSCs in HA-hydrogel submitted for 7 days to mechanical constraint that aimed at mimicking in vivo cardiac beat displayed enhanced cell survival by more than 40% compared to static culture conditions. Thus, the optimized HA-based hydrogel provides a niche for MSCs, which preserves their properties and opens ways for cell therapy, in particular in aortic repair medicine.

Enzymatic scavengers are equally present in stallion testis and epididymis

collection has not been studied. As sexual arousal, mounting of the dummy and ejaculation involve both physical and emotional activity, we hypothesized that semen collection would induce a pronounced stress response. Experiments were performed on two consecutive days using adult experienced breeding stallions (n 1⁄4 16; mean age 6.3 0.7 years) in a semen collection center. Continuous cardiac beat–to-beat interval recordings were made from 30 min before to 30 min after semen collection and were analysed at 1 min-intervals. Saliva for cortisol analysis was collected repeatedly from 60 min before to 120 min after collection of semen. Statistical comparisons were made by ANOVA using a general linear model for repeated measures with day as between subject factor. Semen collection resulted in a significant increase of heart rate (HR) but no differences between experimental days were seen (30 min before semen collection day 1: 36.6 2.3, day 2: 33.4 1.7 beats/min; at semen collection day 1: 94.5 5.1, day 2: 96.1 4.1 beats/min; differences over time P < 0.001, no significant interactions between time and day). In parallel, a significant decrease of the heart rate variability parameter RMSSD (root mean square of successive beat-to-beat differences) was seen reflecting a decrease in vagal activity (30 min before semen collection day 1: 105.9 10.0, day 2: 114.4 11.2 ms; at semen collection day 1: 75.1 8.8, day 2: 61.3 8.1ms; differences over time P < 0.001, no significant interactions between time andday). Values ofHR andRRSMDreturned to baseline values within 15 min after semen collection. No significant changes in salivary cortisol occurred (30 min before semen collectionday1: 1.8 0.2, day2: 1.9 0.2ng/ml,15minafter semen collection day 1: 2.4 0.5, day 2: 2.0 0.2 ng/ml, no significant differences over time, no significant interactions between time and day). In conclusion, breeding stallions respond to the collection of semen with a transient stress response. This is not reflected in salivary cortisol release; however, baseline cortisol concentrations are considerably higher than in stallions not used for breeding. This suggests that in active sires during the breeding season, a continuous activation of adrenal function is present reflecting chronic stress. Thus, at least in individual stallions, stress effects such as impaired immune function cannot be excluded and may contribute to reduced fertility.

Single-beat determination of global longitudinal speckle strain in patients with atrial fibrillation

Although global left ventricular (LV) systolic function is an important determinant of outcome, the assessment of global longitudinal speckle strain (GLS) in patients with atrial fibrillation (AF) is unreliable because of beat-to-beat variation. Previous studies have confirmed that LV contractility of each irregular beat is predicted from the ratio of preceding R-R (RR1) to pre-preceding R-R (RR2) intervals, and the value when the intervals are equal (RR1/RR2=1) estimates the average value of LV contractility. The aim of this study was to assess the clinical feasibility of an index that is obtained on the basis of the RR1/RR2 ratio for the estimation of GLS in patients with AF. We evaluated the RR1/RR2 ratio for the measurement of GLS with apical 4-chamber views in 20 patients with AF. We obtained the GLS for ≥13 cardiac cycles, and the relationship between each GLS at a given cardiac beat and the RR1/RR2 ratio was evaluated by linear regression analysis. The value of GLS at RR1/RR2=1 was compared with the measured average value. The GLS showed a significant correlation with the RR1/RR2 ratio (r=-0.80). The calculated value of GLS at RR1/RR2=1 was quite similar to the average value (-10.17±2.1 % vs. -10.06±2.1%). The GLS of a single beat with identical RR1 and RR2 intervals showed a significant correlation compared with the measured average value over all cardiac cycles (r=0.94, y=0.90x-0.97). The GLS at RR1/RR2=1 allows the LV systolic parameter to be accurately evaluated during AF and obviates the less reliable process of averaging multiple irregular beats.

Proteksi Arus Bocor Pada Instalasi Listrik Dengan Saklar Arus Bocor 30 mA

This research was conducted in order to provide data, information, and earth leakage current protection with ELCB 30 mA. Of this research is expected we all's benefit to know how big ability earth leakage current protection. ELCB really help life being if stung by electricity current. There is ways of working even from ELCB is while happens electricity intermediate contact with human body, therefore current will pass human body making for grounding. ELCB is protection of leak current, so current totaled amount one passes ELCB'S input terminal with terminal its different issue, the difference totaled that current triggers ELCB to decide instantaneous current so lurching aculeate electric gets to be avoided. There is sensitivity even ELCB to detect current is 15 mA, 30 mA and 50 mA. &amp;nbsp;&amp;nbsp;&amp;nbsp; The electric current wreck two vital body functions that are respiration and cardiac beat. Man most one stung electricity current having zoom robustness variably for age. But in general the effect depends on the amount of electricity current flow (ampere). Base on testing of leakage current protection with&amp;nbsp; ELCB 30 mA, it is known that ELCB will trip/off when load current 22,33 A, leakage current is 23.04 mA, and resistance 9.86 K-ohm.

Detection of cardiac arrhythmic beats by logical classifier using binary coding

Cardiac arrhythmia is a rhythmic disorder in heart generated from problems in impulse formation or conduction. Automatic detection of arrhythmia at the time of its occurrence is very essential for continuous cardiac monitoring. As different kinds of arrhythmias produce different morphology of beats, it is difficult to suggest one typical algorithm to classify all kind of arrhythmic beats. In this work, a binary logical classifier is proposed to identify beats such as premature ventricular contraction, bundle branch block, paced and normal. In most of the arrhythmic beats the wave texture is modified along with a change in temporal information. The proposed logical classification requires binary coding of beats based on temporal and morphological features to form a binary array representing the status or signature of the beat. Next the classification is made by the status of the bits depending upon its position in the binary array. This approach of logical classification reduces the complexity of detection because of its binary nature resulting in fast and ready reference of arrhythmic disorder for standalone systems. Performance evaluation results indicate that the method has good accuracy, sensitivity and positive predictivity for all kind of test beats. Moreover, this technique is easily hardware implementable because of its binary nature.

Influence of Image Acquisition Settings on Radiation Dose and Image Quality in Coronary Angiography by 320-Detector Volume Computed Tomography: The CORE320 Pilot Experience

The objective of this study was to investigate the impact of image acquisition settings and patients' characteristics on image quality and radiation dose for coronary angiography by 320-row computed tomography (CT). CORE320 is a prospective study to investigate the diagnostic performance of 320-detector CT for detecting coronary artery disease and associated myocardial ischemia. A run-in phase in 65 subjects was conducted to test the adequacy of the computed tomography angiography (CTA) acquisition protocol. Tube current, exposure window, and number of cardiac beats per acquisition were adjusted according to subjects' gender, heart rate, and body mass index (BMI). Main outcome measures were image quality, assessed by contrast/noise measurements and qualitatively on a 4-point scale, and radiation dose, estimated by the dose-length-product. Average heart rate at image acquisition was 55.0±7.3 bpm. Median Agatston calcium score was 27.0 (interquartile range 1–330). All scans were prospectively triggered. Single heart beat image acquisition was obtained in 61 of 65 studies (94%). Sixty-one studies (94%) and 437 of 455 arterial segments (96%) were of diagnostic image quality. Estimated radiation dose was significantly greater in obese (5.3±0.4 mSv) than normal weight (4.6±0.3 mSv) or overweight (4.7±0.3 mSv) subjects (P<0.001). BMI was the strongest factor influencing image quality (odds ratio=1.457, P=0.005). The CORE320 CTA image acquisition protocol achieved a good balance between image quality and radiation dose for a 320-detector CT system. However, image quality in obese subjects was reduced compared to normal weight subjects, possibly due to tube voltage/current restrictions mandated by the study protocol.

3PS020 心毒性検査での細胞外電位記録における心筋細胞拍動周期制御のための電気刺激方法の最適化(日本生物物理学会第50回年会(2012年度))

3PS020 心毒性検査での細胞外電位記録における心筋細胞拍動周期制御のための電気刺激方法の最適化(日本生物物理学会第50回年会(2012年度))