QRS Amplitude

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Karim Bendjelid - One of the best experts on this subject based on the ideXlab platform.

  • Respiratory change in ECG-wave Amplitude is a reliable parameter to estimate intravascular volume status
    Journal of Clinical Monitoring and Computing, 2013
    Co-Authors: Raphaël Giraud, Nils Siegenthaler, Jacques-a Romand, Denis R. Morel, Laurent Brochard, Karim Bendjelid
    Abstract:

    Electrocardiogram (ECG) is a standard type of monitoring in intensive care medicine. Several studies suggest that changes in ECG morphology may reflect changes in volume status. The “Brody effect”, a theoretical analysis of left ventricular (LV) chamber size influence on QRS-wave Amplitude, is the key element of this phenomenon. It is characterised by an increase in QRS-wave Amplitude that is induced by an increase in ventricular preload. This study investigated the influence of changes in intravascular volume status on respiratory variations of QRS-wave Amplitudes (ΔECG) compared with respiratory pulse pressure variations (ΔPP), considered as a reference standard. In 17 pigs, ECG and arterial pressure were recorded. QRS-wave Amplitude was measured from the Biopac recording to ensure that in all animals ECG electrodes were always at the same location. Maximal QRS Amplitude (ECGmax) and minimal QRS Amplitude (ECGmin) were determined over one respiratory cycle. ΔECG was calculated as 100 × [(ECGmax − ECGmin)/(ECGmax + ECGmin)/2]. ΔECG and ΔPP were simultaneously recorded. Measurements were performed at different time points: during normovolemic conditions, after haemorrhage (25 mL/kg), and following re-transfusion (25 mL/kg) with constant tidal volume (10 mL/kg) and respiration rate (15 breath/min). At baseline, ΔPP and ΔECG were both

  • respiratory change in ecg wave Amplitude is a reliable parameter to estimate intravascular volume status
    Journal of Clinical Monitoring and Computing, 2013
    Co-Authors: Raphaël Giraud, Nils Siegenthaler, Karim Bendjelid, Denis R. Morel, Laurent Brochard, Jacquesandre Romand
    Abstract:

    Electrocardiogram (ECG) is a standard type of monitoring in intensive care medicine. Several studies suggest that changes in ECG morphology may reflect changes in volume status. The "Brody effect", a theoretical analysis of left ventricular (LV) chamber size influence on QRS-wave Amplitude, is the key element of this phenomenon. It is characterised by an increase in QRS-wave Amplitude that is induced by an increase in ventricular preload. This study investigated the influence of changes in intravascular volume status on respiratory variations of QRS-wave Amplitudes (ΔECG) compared with respiratory pulse pressure variations (ΔPP), considered as a reference standard. In 17 pigs, ECG and arterial pressure were recorded. QRS-wave Amplitude was measured from the Biopac recording to ensure that in all animals ECG electrodes were always at the same location. Maximal QRS Amplitude (ECGmax) and minimal QRS Amplitude (ECGmin) were determined over one respiratory cycle. ΔECG was calculated as 100 × [(ECGmax - ECGmin)/(ECGmax + ECGmin)/2]. ΔECG and ΔPP were simultaneously recorded. Measurements were performed at different time points: during normovolemic conditions, after haemorrhage (25 mL/kg), and following re-transfusion (25 mL/kg) with constant tidal volume (10 mL/kg) and respiration rate (15 breath/min). At baseline, ΔPP and ΔECG were both <12 %. ΔPP were significantly correlated with ΔECG (r(2) = 0.89, p < 0.001). Volume loss induced by haemorrhage increased significantly ΔPP and ΔECG. Moreover, during this state, ΔPP were significantly correlated with ΔECG (r(2) = 0.86, p < 0.001). Re-transfusion significantly decreased ΔPP and ΔECG, and ΔPP were significantly correlated with ΔECG (r(2) = 0.90, p < 0.001). The observed correlations between ΔPP and ΔECG at each time point of the study suggest that ΔECG is a reliable parameter to estimate the changes in intravascular volume status and provide experimental confirmation of the "Brody effect."

Tammo Delhaas - One of the best experts on this subject based on the ideXlab platform.

  • Head orientation and electrode placement potentially influence fetal scalp ECG waveform
    PloS one, 2019
    Co-Authors: Alexandra D.j. Hulsenboom, G.j.j. Warmerdam, Janna Weijers, Paul J. Blijham, S. Guid Oei, Judith O. E. H. Van Laar, Rik Vullings, Tammo Delhaas
    Abstract:

    Background Fetal monitoring based on electrocardiographic (ECG) morphology is obtained from a single unipolar fetal scalp electrode. Ideally, it should be obtained from multiple leads, as ECG waveform depends on alignment between electrode and electrical heart axis. This alignment is unknown in fetuses. Besides, fetuses are surrounded by conductive media, which may influence ECG waveform. We explored the influence of electrode position and head orientation on ECG waveforms of unipolar and bipolar scalp ECGs recorded in air and in conductive medium. Methods We recorded ECGs in one adult subject at five different scalp positions in five different head orientations both in dry and immersed conditions. The ratio between T-Amplitude and QRS-Amplitude (T/QRS ratio) of unipolar and bipolar scalp ECGs was determined and compared between all conditions. Results In the dry condition, we observed in the unipolar leads little to no difference between different electrode positions (maximal T/QRS difference 0.00–0.01) and minor differences between head orientations (0.02–0.03), whereas bipolar leads showed no recognizable ECG signal at all. During the immersed condition, we found variation in the unipolar leads, both between electrode positions (maximal T/QRS difference 0.02–0.05) and between head orientations (0.03–0.06). Bipolar leads showed different ECG signals in contrasting head orientations. Conclusions Both unipolar and bipolar scalp lead-derived ECG waveforms are influenced by electrode position and head orientation when the subject is submerged in a conductive medium. Fetal monitoring based on single scalp lead ECG waveform might be suboptimal, as it lacks correction for fetal head orientation and electrode position.

Raphaël Giraud - One of the best experts on this subject based on the ideXlab platform.

  • Respiratory change in ECG-wave Amplitude is a reliable parameter to estimate intravascular volume status
    Journal of Clinical Monitoring and Computing, 2013
    Co-Authors: Raphaël Giraud, Nils Siegenthaler, Jacques-a Romand, Denis R. Morel, Laurent Brochard, Karim Bendjelid
    Abstract:

    Electrocardiogram (ECG) is a standard type of monitoring in intensive care medicine. Several studies suggest that changes in ECG morphology may reflect changes in volume status. The “Brody effect”, a theoretical analysis of left ventricular (LV) chamber size influence on QRS-wave Amplitude, is the key element of this phenomenon. It is characterised by an increase in QRS-wave Amplitude that is induced by an increase in ventricular preload. This study investigated the influence of changes in intravascular volume status on respiratory variations of QRS-wave Amplitudes (ΔECG) compared with respiratory pulse pressure variations (ΔPP), considered as a reference standard. In 17 pigs, ECG and arterial pressure were recorded. QRS-wave Amplitude was measured from the Biopac recording to ensure that in all animals ECG electrodes were always at the same location. Maximal QRS Amplitude (ECGmax) and minimal QRS Amplitude (ECGmin) were determined over one respiratory cycle. ΔECG was calculated as 100 × [(ECGmax − ECGmin)/(ECGmax + ECGmin)/2]. ΔECG and ΔPP were simultaneously recorded. Measurements were performed at different time points: during normovolemic conditions, after haemorrhage (25 mL/kg), and following re-transfusion (25 mL/kg) with constant tidal volume (10 mL/kg) and respiration rate (15 breath/min). At baseline, ΔPP and ΔECG were both

  • respiratory change in ecg wave Amplitude is a reliable parameter to estimate intravascular volume status
    Journal of Clinical Monitoring and Computing, 2013
    Co-Authors: Raphaël Giraud, Nils Siegenthaler, Karim Bendjelid, Denis R. Morel, Laurent Brochard, Jacquesandre Romand
    Abstract:

    Electrocardiogram (ECG) is a standard type of monitoring in intensive care medicine. Several studies suggest that changes in ECG morphology may reflect changes in volume status. The "Brody effect", a theoretical analysis of left ventricular (LV) chamber size influence on QRS-wave Amplitude, is the key element of this phenomenon. It is characterised by an increase in QRS-wave Amplitude that is induced by an increase in ventricular preload. This study investigated the influence of changes in intravascular volume status on respiratory variations of QRS-wave Amplitudes (ΔECG) compared with respiratory pulse pressure variations (ΔPP), considered as a reference standard. In 17 pigs, ECG and arterial pressure were recorded. QRS-wave Amplitude was measured from the Biopac recording to ensure that in all animals ECG electrodes were always at the same location. Maximal QRS Amplitude (ECGmax) and minimal QRS Amplitude (ECGmin) were determined over one respiratory cycle. ΔECG was calculated as 100 × [(ECGmax - ECGmin)/(ECGmax + ECGmin)/2]. ΔECG and ΔPP were simultaneously recorded. Measurements were performed at different time points: during normovolemic conditions, after haemorrhage (25 mL/kg), and following re-transfusion (25 mL/kg) with constant tidal volume (10 mL/kg) and respiration rate (15 breath/min). At baseline, ΔPP and ΔECG were both <12 %. ΔPP were significantly correlated with ΔECG (r(2) = 0.89, p < 0.001). Volume loss induced by haemorrhage increased significantly ΔPP and ΔECG. Moreover, during this state, ΔPP were significantly correlated with ΔECG (r(2) = 0.86, p < 0.001). Re-transfusion significantly decreased ΔPP and ΔECG, and ΔPP were significantly correlated with ΔECG (r(2) = 0.90, p < 0.001). The observed correlations between ΔPP and ΔECG at each time point of the study suggest that ΔECG is a reliable parameter to estimate the changes in intravascular volume status and provide experimental confirmation of the "Brody effect."

Stephen W Smith - One of the best experts on this subject based on the ideXlab platform.

  • comparison of the QRS complex st segment and t wave among patients with left bundle branch block with and without acute myocardial infarction
    Journal of Emergency Medicine, 2016
    Co-Authors: Kenneth W Dodd, Stephen W Smith, Kendra D Elm
    Abstract:

    Abstract Background The modified Sgarbossa criteria have been validated as a rule for diagnosis of acute coronary occlusion (ACO) in left bundle branch block (LBBB). However, no analysis has been done on differences in the QRS complex, T-wave, or ST-segment concordance of Objective We compare findings involving the QRS Amplitude, ST-segment morphology, ST-concordance  Methods Retrospectively, emergency department patients were identified with LBBB and ischemic symptoms but no MI, with angiographically proven ACO, and with non-STEMI. Results ACO, non-STEMI, and no MI groups consisted of 33, 24, and 105 patients. The sum of the maximum deflection of the QRS Amplitude across all leads (ΣQRS) was smaller in patients with ACO than those without ACO (101.5 mm vs. 132.5 mm; p Conclusions We found differences in QRS Amplitude, ST-segment morphology, and T-waves between patients with LBBB and ACO, non-STEMI, and no MI. However, none of these criteria outperformed the modified Sgarbossa criteria for diagnosis of ACO in LBBB.

  • validation of the modified sgarbossa criteria for acute coronary occlusion in the setting of left bundle branch block a retrospective case control study
    American Heart Journal, 2015
    Co-Authors: Pendell H Meyers, Alexander T Limkakeng, Elias Jaffa, Anjni Patel, Jason B Theiling, Salim R Rezaie, Todd Stewart, Cassandra Zhuang, Vijaya K Pera, Stephen W Smith
    Abstract:

    Background The modified Sgarbossa criteria were proposed in a derivation study to be superior to the original criteria for diagnosing acute coronary occlusion (ACO) in left bundle branch block (LBBB). The new rule replaces the third criterion (5 mm of excessively discordant ST elevation [STE]) with a proportion (at least 1 mm STE and STE/S wave ≤−0.25). We sought to validate the modified criteria. Methods This retrospective case-control study was performed by chart review in 2 tertiary care center emergency departments (EDs) and 1 regional referral center. A billing database was used at 1 site to identify all ED patients with LBBB and ischemic symptoms between May 2009 and June 2012. In addition, all 3 sites identified LBBB ACO patients who underwent emergent catheterization. We measured QRS Amplitude and J-point deviation in all leads, blinded to outcomes. Acute coronary occlusion was determined by angiographic findings and cardiac biomarker levels, which were collected blinded to electrocardiograms. Diagnostic statistics of each rule were calculated and compared using McNemar's test. Results Our consecutive cohort search identified 258 patients: 9 had ACO, and 249 were controls. Among the 3 sites, an additional 36 cases of ACO were identified, for a total of 45 ACO cases and 249 controls. The modified criteria were significantly more sensitive than the original weighted criteria (80% vs 49%, P P P = .5) but was significantly greater than the original unweighted criteria (99% vs 94%, P = .004). Conclusions The modified Sgarbossa criteria were superior to the original criteria for identifying ACO in LBBB.

  • electrocardiographic criteria to differentiate acute anterior st elevation myocardial infarction from left ventricular aneurysm
    American Journal of Emergency Medicine, 2015
    Co-Authors: Lauren R Klein, Gautam R Shroff, William Beeman, Stephen W Smith
    Abstract:

    Abstract Background ST elevation (STE) on the electrocardiogram (ECG) may be due to acute myocardial infarction (AMI) or other nonischemic pathologies such as left ventricular aneurysm (LVA). The objective of this study was to validate 2 previously derived ECG rules to distinguish AMI from LVA. The first rule states that if the sum of T-wave Amplitudes in leads V1 to V4 divided by the sum of QRS Amplitudes in leads V1 to V4 is greater than 0.22, then acute ST-segment elevation MI is predicted. The second rule states that if any 1 lead (V1-V4) has a T-wave Amplitude to QRS Amplitude ratio greater than or equal to 0.36, then acute ST-segment elevation MI is predicted. Methods This was a retrospective analysis of patients with AMI (n = 59) and LVA (n = 16) who presented with ischemic symptoms and STE on the ECG. For each ECG, the T-wave Amplitude and QRS Amplitude in leads V1 to V4 were measured. These measurements were applied to the 2 ECG rules; and sensitivity, specificity, and accuracy in predicting AMI vs LVA were calculated. Results For rule 1 (sum of ratios in V1-V4), sensitivity was 91.5%, specificity was 68.8%, and accuracy was 86.7% in predicting AMI. For rule 2 (maximum ratio in V1-V4), sensitivity was 91.5%, specificity was 81.3%, and accuracy was 89.3% in predicting AMI. Conclusions When patients present to the emergency department with ischemic symptoms and the differential diagnosis for STE on the ECG is AMI vs LVA, these 2 ECG rules may be helpful in differentiating these 2 pathologies. Both rules are highly sensitive and accurate in predicting AMI vs LVA.

  • t QRS ratio best distinguishes ventricular aneurysm from anterior myocardial infarction
    American Journal of Emergency Medicine, 2005
    Co-Authors: Stephen W Smith
    Abstract:

    Abstract Objectives Reperfusion therapy for acute myocardial infarction (AMI) is indicated in the presence of ST elevation (STE) and ischemic symptoms. Previous MI may present with persistent STE or "left ventricular aneurysm" (LVA) morphology that mimics AMI. Hypothesis A high ratio of T Amplitude to QRS Amplitude best distinguishes AMI from LVA. Methods This was a retrospective cohort analysis. Patients with anatomical LVA by echocardiography were identified and those who presented to the ED with ischemic symptoms and STE of at least 1 mm in 2 consecutive leads and ruled out for acute left anterior descending coronary artery (LAD) occlusion were selected. Electrocardiograms (ECGs) were compared with a control group of 37 consecutive anterior AMI (aAMI) with proven acute LAD occlusion. Bundle-branch block was excluded. Various ECG measurements and ratios were compared. Results Twenty patients with LVA met the inclusion criteria. The best discriminator was T Amplitude sum to QRS Amplitude sum ratio V1-V4, misclassifying only 4 (6.8%) of 59 cases at a cutoff of >0.22 for AMI. For aAMI and LVA, respectively, mean (±95% CI) ratio of the sum of T Amplitudes in V 1 to V 4 to the sum of QRS Amplitude in V 1 -V 4 was 0.54 ± 0.085 and 0.16 ± 0.021 ( P 0.22; the false negatives (ratio P -7 ). Conclusion T Amplitude/QRS Amplitude ratio best distinguishes aAMI from LVA in ECGs that meet STE criteria for reperfusion therapy. A high ratio is associated with an AMI.

Nils Siegenthaler - One of the best experts on this subject based on the ideXlab platform.

  • Respiratory change in ECG-wave Amplitude is a reliable parameter to estimate intravascular volume status
    Journal of Clinical Monitoring and Computing, 2013
    Co-Authors: Raphaël Giraud, Nils Siegenthaler, Jacques-a Romand, Denis R. Morel, Laurent Brochard, Karim Bendjelid
    Abstract:

    Electrocardiogram (ECG) is a standard type of monitoring in intensive care medicine. Several studies suggest that changes in ECG morphology may reflect changes in volume status. The “Brody effect”, a theoretical analysis of left ventricular (LV) chamber size influence on QRS-wave Amplitude, is the key element of this phenomenon. It is characterised by an increase in QRS-wave Amplitude that is induced by an increase in ventricular preload. This study investigated the influence of changes in intravascular volume status on respiratory variations of QRS-wave Amplitudes (ΔECG) compared with respiratory pulse pressure variations (ΔPP), considered as a reference standard. In 17 pigs, ECG and arterial pressure were recorded. QRS-wave Amplitude was measured from the Biopac recording to ensure that in all animals ECG electrodes were always at the same location. Maximal QRS Amplitude (ECGmax) and minimal QRS Amplitude (ECGmin) were determined over one respiratory cycle. ΔECG was calculated as 100 × [(ECGmax − ECGmin)/(ECGmax + ECGmin)/2]. ΔECG and ΔPP were simultaneously recorded. Measurements were performed at different time points: during normovolemic conditions, after haemorrhage (25 mL/kg), and following re-transfusion (25 mL/kg) with constant tidal volume (10 mL/kg) and respiration rate (15 breath/min). At baseline, ΔPP and ΔECG were both

  • respiratory change in ecg wave Amplitude is a reliable parameter to estimate intravascular volume status
    Journal of Clinical Monitoring and Computing, 2013
    Co-Authors: Raphaël Giraud, Nils Siegenthaler, Karim Bendjelid, Denis R. Morel, Laurent Brochard, Jacquesandre Romand
    Abstract:

    Electrocardiogram (ECG) is a standard type of monitoring in intensive care medicine. Several studies suggest that changes in ECG morphology may reflect changes in volume status. The "Brody effect", a theoretical analysis of left ventricular (LV) chamber size influence on QRS-wave Amplitude, is the key element of this phenomenon. It is characterised by an increase in QRS-wave Amplitude that is induced by an increase in ventricular preload. This study investigated the influence of changes in intravascular volume status on respiratory variations of QRS-wave Amplitudes (ΔECG) compared with respiratory pulse pressure variations (ΔPP), considered as a reference standard. In 17 pigs, ECG and arterial pressure were recorded. QRS-wave Amplitude was measured from the Biopac recording to ensure that in all animals ECG electrodes were always at the same location. Maximal QRS Amplitude (ECGmax) and minimal QRS Amplitude (ECGmin) were determined over one respiratory cycle. ΔECG was calculated as 100 × [(ECGmax - ECGmin)/(ECGmax + ECGmin)/2]. ΔECG and ΔPP were simultaneously recorded. Measurements were performed at different time points: during normovolemic conditions, after haemorrhage (25 mL/kg), and following re-transfusion (25 mL/kg) with constant tidal volume (10 mL/kg) and respiration rate (15 breath/min). At baseline, ΔPP and ΔECG were both <12 %. ΔPP were significantly correlated with ΔECG (r(2) = 0.89, p < 0.001). Volume loss induced by haemorrhage increased significantly ΔPP and ΔECG. Moreover, during this state, ΔPP were significantly correlated with ΔECG (r(2) = 0.86, p < 0.001). Re-transfusion significantly decreased ΔPP and ΔECG, and ΔPP were significantly correlated with ΔECG (r(2) = 0.90, p < 0.001). The observed correlations between ΔPP and ΔECG at each time point of the study suggest that ΔECG is a reliable parameter to estimate the changes in intravascular volume status and provide experimental confirmation of the "Brody effect."