The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Hans Kirkegaard - One of the best experts on this subject based on the ideXlab platform.
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Variations in the pre-ejection period induced by ventricular extra systoles may be feasible to predict fluid responsiveness
Journal of Clinical Monitoring and Computing, 2014Co-Authors: Simon Tilma Vistisen, Kristian Kjær Andersen, Christian Alcaraz Frederiksen, Hans KirkegaardAbstract:Monitoring that can predict fluid responsiveness is an unsettled matter for spontaneously breathing patients. Based on the convincing results with dynamic monitoring based on preload variations induced by mechanical ventilation, we hypothesised that the extra systolic post-Ectopic Beat could constitute a similar intermittent preload shift inducing a brief variation in blood pressure and that the magnitude of this variation could predict the hemodynamic response to volume expansion in sedated pigs. Ten pigs were sedated and hemodynamically monitored and four intravascular volume shifts were made: blood depletion (25 % of estimated blood volume; 660 ml), retransfusion (of 500 ml depleted blood), and two sequential volume expansions (500 ml colloid each). Between volume shifts, supraventricular and ventricular extra systoles were induced by a pacemaker. Hemodynamic variables such as pulse pressure (PP) and pre-ejection period (PEP) were determined for each heart Beat and the hemodynamic changes in the post-Ectopic Beats compared to sinus Beats was extracted (e.g. ∆PP and ∆PEP) and used to predict fluid responsiveness of subsequent volume expansions which was determined by receiver operating characteristic (ROC) curves. Ventricular extra systoles were generally useful for fluid responsiveness prediction (ROC areas >0.65). ∆PEP variables best predicted fluid responsiveness: ∆PEP derived from arterial pressure curve and ECG had ROC area of 0.84 and sensitivity of 0.77 and specificity of 0.71; ∆PEP derived from plethysmographic curve and ECG had ROC area of 0.79 and sensitivity of 0.71 and specificity of 0.70. However, ∆PP was not a useful variable in this study (ROC area
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Variations in the pre-ejection period induced by ventricular extra systoles may be feasible to predict fluid responsiveness
Journal of Clinical Monitoring and Computing, 2014Co-Authors: Simon Tilma Vistisen, Kristian Kjær Andersen, Christian Alcaraz Frederiksen, Hans KirkegaardAbstract:Monitoring that can predict fluid responsiveness is an unsettled matter for spontaneously breathing patients. Based on the convincing results with dynamic monitoring based on preload variations induced by mechanical ventilation, we hypothesised that the extra systolic post-Ectopic Beat could constitute a similar intermittent preload shift inducing a brief variation in blood pressure and that the magnitude of this variation could predict the hemodynamic response to volume expansion in sedated pigs. Ten pigs were sedated and hemodynamically monitored and four intravascular volume shifts were made: blood depletion (25 % of estimated blood volume; 660 ml), retransfusion (of 500 ml depleted blood), and two sequential volume expansions (500 ml colloid each). Between volume shifts, supraventricular and ventricular extra systoles were induced by a pacemaker. Hemodynamic variables such as pulse pressure (PP) and pre-ejection period (PEP) were determined for each heart Beat and the hemodynamic changes in the post-Ectopic Beats compared to sinus Beats was extracted (e.g. ∆PP and ∆PEP) and used to predict fluid responsiveness of subsequent volume expansions which was determined by receiver operating characteristic (ROC) curves. Ventricular extra systoles were generally useful for fluid responsiveness prediction (ROC areas >0.65). ∆PEP variables best predicted fluid responsiveness: ∆PEP derived from arterial pressure curve and ECG had ROC area of 0.84 and sensitivity of 0.77 and specificity of 0.71; ∆PEP derived from plethysmographic curve and ECG had ROC area of 0.79 and sensitivity of 0.71 and specificity of 0.70. However, ∆PP was not a useful variable in this study (ROC area
Simon Tilma Vistisen - One of the best experts on this subject based on the ideXlab platform.
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Post-extrasystolic characteristics in the arterial blood pressure waveform are associated with right ventricular dysfunction in intensive care patients
Journal of Clinical Monitoring and Computing, 2019Co-Authors: Simon Tilma Vistisen, Benjamin Moody, Leo Anthony Celi, Christina ChenAbstract:Right ventricular dysfunction (RVD) is associated with end-organ dysfunction and mortality, but has been an overlooked condition in the ICU. We hypothesized that analysis of the arterial waveform in the presence of ventricular extrasystoles could differentiate patients with RVD from patients with a normally functioning right ventricle, because the 2nd and 3rd post-Ectopic Beat could reflect right ventricular state (pulmonary transit time) during the preceding ectopy. We retrospectively identified patients with echocardiographic evidence of moderate-to-severe RVD and patients with a normal functioning right ventricle (control) from the MIMIC database. We identified waveform records where ECG and arterial pressure were available in combination, simultaneously with echocardiographic evaluation. Ventricular extrasystoles were visually confirmed and the median systolic blood pressure (SBP) of the 2nd and 3rd post-Ectopic Beats compared with the median SBP of the ten sinus Beats preceding the extrasystole. We identified 34 patients in the control group and 24 patients in the RVD group with ventricular extrasystoles. The mean SBP reduction at the 2nd and 3rd Beat was lower in the RVD group compared with the control group [− 1.7 (SD: 1.9) % vs. − 3.6 (SD: 1.9) %, p
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Variations in the pre-ejection period induced by ventricular extra systoles may be feasible to predict fluid responsiveness
Journal of Clinical Monitoring and Computing, 2014Co-Authors: Simon Tilma Vistisen, Kristian Kjær Andersen, Christian Alcaraz Frederiksen, Hans KirkegaardAbstract:Monitoring that can predict fluid responsiveness is an unsettled matter for spontaneously breathing patients. Based on the convincing results with dynamic monitoring based on preload variations induced by mechanical ventilation, we hypothesised that the extra systolic post-Ectopic Beat could constitute a similar intermittent preload shift inducing a brief variation in blood pressure and that the magnitude of this variation could predict the hemodynamic response to volume expansion in sedated pigs. Ten pigs were sedated and hemodynamically monitored and four intravascular volume shifts were made: blood depletion (25 % of estimated blood volume; 660 ml), retransfusion (of 500 ml depleted blood), and two sequential volume expansions (500 ml colloid each). Between volume shifts, supraventricular and ventricular extra systoles were induced by a pacemaker. Hemodynamic variables such as pulse pressure (PP) and pre-ejection period (PEP) were determined for each heart Beat and the hemodynamic changes in the post-Ectopic Beats compared to sinus Beats was extracted (e.g. ∆PP and ∆PEP) and used to predict fluid responsiveness of subsequent volume expansions which was determined by receiver operating characteristic (ROC) curves. Ventricular extra systoles were generally useful for fluid responsiveness prediction (ROC areas >0.65). ∆PEP variables best predicted fluid responsiveness: ∆PEP derived from arterial pressure curve and ECG had ROC area of 0.84 and sensitivity of 0.77 and specificity of 0.71; ∆PEP derived from plethysmographic curve and ECG had ROC area of 0.79 and sensitivity of 0.71 and specificity of 0.70. However, ∆PP was not a useful variable in this study (ROC area
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Variations in the pre-ejection period induced by ventricular extra systoles may be feasible to predict fluid responsiveness
Journal of Clinical Monitoring and Computing, 2014Co-Authors: Simon Tilma Vistisen, Kristian Kjær Andersen, Christian Alcaraz Frederiksen, Hans KirkegaardAbstract:Monitoring that can predict fluid responsiveness is an unsettled matter for spontaneously breathing patients. Based on the convincing results with dynamic monitoring based on preload variations induced by mechanical ventilation, we hypothesised that the extra systolic post-Ectopic Beat could constitute a similar intermittent preload shift inducing a brief variation in blood pressure and that the magnitude of this variation could predict the hemodynamic response to volume expansion in sedated pigs. Ten pigs were sedated and hemodynamically monitored and four intravascular volume shifts were made: blood depletion (25 % of estimated blood volume; 660 ml), retransfusion (of 500 ml depleted blood), and two sequential volume expansions (500 ml colloid each). Between volume shifts, supraventricular and ventricular extra systoles were induced by a pacemaker. Hemodynamic variables such as pulse pressure (PP) and pre-ejection period (PEP) were determined for each heart Beat and the hemodynamic changes in the post-Ectopic Beats compared to sinus Beats was extracted (e.g. ∆PP and ∆PEP) and used to predict fluid responsiveness of subsequent volume expansions which was determined by receiver operating characteristic (ROC) curves. Ventricular extra systoles were generally useful for fluid responsiveness prediction (ROC areas >0.65). ∆PEP variables best predicted fluid responsiveness: ∆PEP derived from arterial pressure curve and ECG had ROC area of 0.84 and sensitivity of 0.77 and specificity of 0.71; ∆PEP derived from plethysmographic curve and ECG had ROC area of 0.79 and sensitivity of 0.71 and specificity of 0.70. However, ∆PP was not a useful variable in this study (ROC area
Franco Rengo - One of the best experts on this subject based on the ideXlab platform.
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relationship between ventricular Ectopic Beat frequency and heart rate study in patients with severe arrhythmias
American Heart Journal, 1993Co-Authors: Domenico Acanfora, Lorenzo De Caprio, Annalisa Di Palma, Giuseppe Furgi, Fortunato Marciano Ing, Marie Louise Migaux, Franco RengoAbstract:Abstract To evaluate and quantify the relationship between premature ventricular contractions (PVCs) and heart rate (HR), 57 patients (48 men and 8 women, mean age 59.8 ± 7.9 years) with severe PVCs (Lown-Wolf grade ≥3a) over 24 hours of Holter monitoring were studied. Twenty had no coronary artery disease (CAD), 25 had angiographically documented CAD, and 12 had acute myocardial infarction. All parameters of the 24-hour recordings from two ECG leads were measured by a Holter analyzer designed in our laboratory, based on fast microprocessors and controlled by a microcomputer. Scatter diagrams of the number of PVCs per minute as a function of HR and correlation coefficient were computed for various HR values corresponding to a total number of minutes greater than five. A positive correlation ( r ≥ 0.35) was found in most patients without CAD (85%); there was a complex relationship between the strength of the correlation and the presence of CAD or acute myocardial infarction because of a greater variability in the results of correlation coefficient analysis (coefficient of variation 62%, 208%, and 145% in patients without CAD, with CAD, and with acute myocardial infarction, respectively). The incidence of a positive correlation was similar in patients with Lown-Wolf grade III (63%), IVa (82%), or ≥IVb (67%) arrhythmias. The reproducibility of the correlation coefficient of the relationship between PVC frequency and HR was tested in 15 patients. The mean value of the correlation coefficient was 0.801 ± 0.169 for the first test and 0.805 ± 0.22 ( p = NS) for the second test. Results of our study show a positive correlation between PVCs and HR in patients without CAD but not in those with CAD or acute myocardial infarction. This is because of a greater variability in coefficient of correlation analysis in the latter patients, even though our mathematical model shows good short-term reproducibility.
Edward J. Vigmond - One of the best experts on this subject based on the ideXlab platform.
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Arrhythmogenesis by single Ectopic Beats originating in the Purkinje system.
American journal of physiology. Heart and circulatory physiology, 2010Co-Authors: Makarand Deo, Patrick M. Boyle, Albert M. Kim, Edward J. VigmondAbstract:Cells in the Purkinje system (PS) are known to be more vulnerable than ventricular myocytes to secondary excitations during the action potential (AP) plateau or repolarization phases, known as early afterdepolarizations (EADs). Since myocytes have a lower intrinsic AP duration than the PS cells to which they are coupled, EADs occurring in distal branches of the PS are more likely to result in propagating Ectopic Beats. In this study, we use a computer model of the rabbit ventricles and PS to investigate the consequences of EADs occurring at different times and places in the cardiac conduction system. We quantify the role of tissue conductivity and excitability, as well as interaction with sinus excitation, in determining whether an EAD-induced Ectopic Beat will establish reentrant activity. We demonstrate how a single Ectopic Beat arising from an EAD in the distal PS can give rise to reentrant arrhythmia; in contrast, EADs in the proximal PS were unable to initiate reentry. Clinical studies have established the PS as a potential substrate for reentry, but the underlying mechanisms of these types of disorder are not well understood, nor are conditions leading to their development clearly defined; this work provides new insights into the role of the PS in such circumstances. Our findings indicate that simulated EADs in the distal PS can induce premature Beats, which can lead to the tachycardias involving the conduction system due to interactions with sinus activity or impaired myocardial conduction velocity.
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the effect of vagally induced dispersion of action potential duration on atrial arrhythmogenesis
Heart Rhythm, 2004Co-Authors: Edward J. Vigmond, Vincent Tsoi, Hermenigeld Arevalo, James Kneller, Stanley Nattel, Natalia A TrayanovaAbstract:Abstract Objective The purpose of this study is to ascertain the effects of spatially variable ACh distributions on arrhythmogenesis in a morphologically realistic computer model of canine atria. Background Vagal stimulation releases acetylcholine (ACh), which causes a dose-dependent reduction in action potential duration (APD) in the atria. Due to the nonuniform distribution of nerve endings, APD dispersion may result, which has been shown to play a role in the breakup of activity. Methods Reentry was initiated in a computationally efficient, morphologically realistic computer model of the atria. Discrete regions corresponding to ACh release sites, referred to as islands, were assigned shortened APDs in an ACh-dependent fashion. Island APD was varied as well as the basal APD. The window of vulnerability for Ectopic Beat-induction of sustained reentry was determined for both left atrial(LA) and right atrial (RA) stimulation. The resulting reentries were categorized based on type and location. Results 1) Atrial geometry severely restricts the formation of reentrant circuits. 2) Wave fractionation only occurred for large differences between island and basal APD. 3) Small ACh concentration differences produced stable figure-of-8 reentrant patterns. 4) Large islands displayed more wave breakup but could sometimes anchor reentries. Conclusions Large APD gradients produced by ACh heterogeneity can lead to a breakdown of organized activity.
R Avasthi - One of the best experts on this subject based on the ideXlab platform.
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correlation between dispersion of repolarization qt dispersion and ventricular Ectopic Beat frequency in patients with acute myocardial infarction a marker for risk of arrhythmogenesis
International Journal of Cardiology, 2004Co-Authors: Hitender Jain, R AvasthiAbstract:Abstract Background: QT dispersion (QTd) has evoked a lot of interest in recent years as regards the basic concept of dispersion of repolarization, which it is supposed to reflect on a surface ECG, as being a marker or substrate for arrhythmogenesis. QTd has been shown to be high in patients with ventricular fibrillation and tachycardia. But there is still some debate about its possible role as a marker or substrate for arrhythmogenesis. We studied whether it has any correlation with simple benign ventricular Ectopic Beats (VEB) after acute myocardial infarction. Study: We studied four different dispersion parameters (QTd, QTcd, JTcd, AQTd) on 2 different days after AMI and also obtained a 24-h ambulatory ECG on the 2nd day after admission in 64 out of a total of 90 patients. Patients were divided into five groups based on VEB frequency/h on a 24-h ambulatory ECG. Results: We found a gradual increase in dispersion parameters across the five groups with increasing frequency of VEB. A significant difference was noticed between group 1 (VEB 0.0–0.9/h) and group V (>30/h) on the day of admission: QTd 88.8±28.5 versus 123.3±23.4, P P P P Conclusion: We hypothesize that with increasing dispersion of repolarization the chances or the frequency of ventricular arrhythmias increase. Our findings also point to a definite role of QTd as an arrhythmogenic marker or substrate.
