Calvo, M.; Gomis, P.; Hernández, A.; Arbelo, E.; Andreu, D.; Caminal, P. ICCB - International Conference on Computational Bioengineering p. 138 Presentation's date: 2015-09-15 Presentation of work at congresses
Brugada syndrome is an inherited disease characterized by a specific electrocardiographic pattern as well as an increased risk of cardiac arrhythmias and sudden death . There are currently no objective indicators to determine individual risk, so the eligibility for the implantation of implantable cardioverter defibrillators to prevent sudden death events still generates controversy.
Since the electrocardiogram (ECG) provides with noninvasively heart information, this work presents an automatic algorithm able to detect significant electrocardiographic parameters in the disease, such as the Brugada-like pattern burden on 24-hour continuous ECG monitoring. The algorithm integrates a previously developed and validated ECG delineator in order to locate the beginning, peak and ending of cardiac waves . Then, it classifies each beat between normal or Brugada based on the morphology of the detected waves. Likewise, the algorithm proposes an expansion focused on detecting ST-segment elevation, PR, QRS and QTc intervals duration, heart rate variability and premature ventricular contractions load, among others.
The detector validation was based on the assessment of the 24-hour 12-lead ECG signals of a high-risk Brugada patient from the Hospital Clínic de Barcelona, in Spain. The subject carried the Holter monitor SEER 12 (GE Healthcare Inc., Milwaukee, WI, USA) for a whole day, placing the electrodes in a regular Mason-Likar 12-lead ECG system configuration and recording at a sampling frequency of 128 Hz. The obtained sensitivity and specificity of a random sample of 600 beats across the 12 leads (50 beats/lead) were of 93.7% and 98.69%, respectively. Erroneous detections resulted from incorrect T-wave delineations in noisy segments.
Future work will be focused on testing the performed algorithm in an extensive sample of patients diagnosed with Brugada syndrome that, based on their cardiac events, will automatically determine the association of these ECG parameters with the individual risk of suffering sudden cardiac death.
Aim: Baroreflex sensitivity (BRS) is a valuable index to assess cardiovascular autonomic control and therefore to provide prognostic evaluation in many cardiac diseases. Although several methods have been developed to capture spontaneous BRS noninvasively, they are difficult to compare and often provide conflicting results. This study analyzed eight different BRS estimates obtained from a clinical series of patients suffering from Brugada syndrome, in order to quantify the agreement between measures.
Methods: Thirty-seven patients diagnosed with Brugada syndrome took part in a head-up tilt test while noninvasive blood pressure recordings were collected. The test was divided into three phases, leading to 111 BRS results with each method: i) supine rest for 10 minutes, ii) tilting with an inclination of 60° for 45 minutes or until the test was positive and iii) rest in supine position for 10 minutes. Eight BRS estimates were compared in all phases: (1) BRS+/+ and (2) BRS-/- from sequence analysis, (3) BRS-LF, (4) BRS-HF, (5) BRS-LHF, (6) BRS-TF1 and (7) BRS-TF2 from cross-spectral analysis and (8) BRS-SD.
Results: Measures resulting from the sequence method failed to provide results in over 30 recordings, whereas BRS-SD and BRS-TF2 gave results in all cases. All methods captured a decrease in response to tilting, but BRS+/+ and BRS-/- obtained higher BRS after the test with respect to baseline. Moreover, these estimates showed low agreement with the remaining methods based on intra-class correlation coefficient results (BRS+/+: r = 0.21 ± 0.12, BRS-/-: r = 0.27 ± 0.15). Assuming an age-associated reduction in BRS, which has been previously reported, the lowest Pearson’s correlation coefficients came from sequence analysis results (r = -0.28 ± 0.03).
Conclusion: Among the BRS estimates analyzed, those derived from sequence analysis showed a lower reliability when capturing baroreflex function in a clinical series of Brugada syndrome patients.
Calvo, M.; Gomis, P.; Andreu, D.; Caminal, P.; Arbelo, E. Congreso Anual de la Sociedad Española de Ingeniería Biomédica p. 768-1-768-4 Presentation's date: 2014-11-27 Presentation of work at congresses
El síndrome de Brugada es una enfermedad hereditaria caracterizada por un patrón electrocardiográfico característico, así como por un aumento del riesgo de sufrir arritmias cardíacas y muerte súbita. No existen actualmente indicadores objetivos que permitan determinar el riesgo individual, por lo que la elegibilidad para la implantación de desfibriladores automáticos implantables con el fin de prevenir eventos de muerte súbita genera todavía gran controversia. Dado que el electrocardiograma (ECG) proporciona información cardíaca de forma no invasiva, se presenta un algoritmo automático capaz de detectar parámetros electrocardiográficos relevantes en la enfermedad. De este modo, futuros estudios que incluyan grandes series de pacientes permitirán determinar el valor pronóstico de las diferentes variables detectadas. El algoritmo integra funciones disponibles previamente desarrolladas para la lectura y delineación de señales ECG y propone una expansión centrada en la detección de parámetros como la carga de latidos con patrón de Brugada, elevación del segmento ST, duración del segmento ST y de los intervalos PR, QRS y QTc, la variabilidad del ritmo cardíaco (VRC), la alternancia de la onda T o la carga de extrasístoles ventriculares, entre otros. El código se testeó en registros ECG continuos de 12 derivaciones y 24 horas de duración de dos pacientes con diferentes grados de severidad y un caso control, obteniendo tendencias relacionadas con la VRC y la carga de latidos con patrón de Brugada. Asimismo, se analizaron diferentes colocaciones de los electrodos con el objetivo de concluir la configuración más sensible para la detección del patrón característico.
High frequency (HF) QRS fragmentation and very-low amplitude abnormal intra-QRS potential (uAIQP) analyses have been used to track ischemic changes during coronary artery occlusions. The aim of this study was to assess the relationship between these two techniques in detecting acute myocardial ischemia and the effects of a previous myocardial infarction (MI).
Fifty-six patients who underwent elective percutaneous coronary intervention (PCI) procedures were selected and classified into 2 groups according to the presence of prior healed MI (old-MI) (n=18) or not (no_MI) (n=38). Continuous ECG before and during the PCI were
recorded and signal-averaged. uAIQPs were obtained using a signal modelling approach. HFQRSRMS was obtained by band pass filtering the ECGs at 150 to 250 Hz. QRS-HFpower was estimated from a modeling power spectral technique. uAIQP and HF indices were
obtained from a baseline and an occlusion-PCI ECG episode.
uAIQP and HF values decreased (p<0.05) for each of the 12 leads at the PCI event respect to baseline in all patients and the no-MI group. Changes in uAIQP or HF did not separate the groups. uAIQP and QRS-HFpower values at baseline were lower in all leads, except V1-V2,
in the old-MI groups compared to no-MI (p<0.05). Pearson’s correlation showed moderate relationship among the indices in most of leads.
High-frequency QRS fragmentation indices could add diagnostic value to ST analysis for diagnosing ischemia when a baseline ECG information is available. Patients with old-MI presented lower uAIQP amplitudes compared to no-MI, however further studies are needed to elucidate the effects of old MI on very-low level fragmentation of the QRS.
Introduction: Low-level electrocardiographic changes from depolarization wavefront may accompany acute myocardial ischemia. The purpose of this study was to assess the changes of microvolt amplitude intra-QRS potentials induced by elective percutaneous coronary interventions (PCI).; Methods: Fifty-seven patients with balloon inflation periods ranging from 3.1 to 7.3 minutes (4.9 +/- 0.7 min) were studied. Nine leads continuous high-resolution ECG before and during PCI were recorded and signal-averaged. Abnormal intra-QRS at microvolt level (mu AIQP) were obtained using a signal modeling approach. mu AIQP, R-wave amplitude and QRS duration were measured in the processed ECG during baseline and PCI episodes.; Results: The mean mu AIQP amplitude significantly decreased for each of the standard 12 leads at the PCI event respect to baseline. Left anterior descending artery (LAD) occlusion resulted in a decrease mu AIQP in both the precordial leads and the limb leads, while right coronary (RCA) and left circumflex (LCx) arteries occlusions mainly affected limb leads. R-wave amplitude increased during PCI in RCA and LCx groups in lead III but decreased in the precordial leads, while the amplitude decreased in the LAD group in lead III. The average duration of the QRS augmented in groups RCA and LCx but not in the LAD group.; Conclusions: Abnormal intra-QRS potentials at the level of mu V provide an excellent tool to characterize the very-low amplitude fragmentation of the QRS complex and its changes due to ischemic injuries. mu AIQP shows promise as a new ECG index to measure electrophysiologic changes associated with acute myocardial ischemia. (c) 2014 The Authors. Published by Elsevier Inc.
Myocardial ischemia may lead to significant changes in autonomic control of heart rate (HR) affecting its variability and alter beat-to-beat ventricular repolarization periods. We hypothesized that transient myocardial ischemia affects the complex dynamics of the HR and QT. The aim of this study was to assess the RR and QT interval time series complexity using Higuchi’s fractal dimension (HFD) during prolonged balloon occlusion of one of the major coronary arteries.
Eighty-five patients who underwent elective percutaneous coronary intervention procedures were selected. Patients were classified into 2 groups according to the presence of prior healed myocardial infarction (INF) (n = 29) or not (No_INF) (n = 56). RR, QT and QTc (Bazzet’s formula) time series were obtained from continuous ECG. Three 3-minute stages were chosen: (1) preinflation as baseline (pre), (2) from the start of occlusion (pci), and (3) immediately post deflation (post_pci). HFD was calculated on each 3-minute stage time series to quantify the changing complexity and self-similarity of RR, QT and QTc time series (HFD RR, HFD QT and HFD QTc, respectively). Cohen’s d statistics were included to measure the effect size of the procedure.
HFD values decreased significantly from baseline to pci and post_pci in the three time-series. HFD RR, 1.76 ± 0.13 vs. 1.69 ± 0.15 (p<0.001, Cohen’s d = -0.64); HFD QT, 1.90 ± 0.11 vs 1.82 ± 0.13 (p<0.001, d = -0.67); HFD QTc, 1.88 ± 0.09 vs. 1.83 ± 0.11 (p<0.01, d= -0.46). The HFD reduction was greater from baseline to post_pci (p<0.001, d = -0.99 (RR), d = -1.02 (QT)). HFD of QT intervals decreases during the procedure predominantly in the No_INF group.
The time series studied, related to autonomic control of HR and to the variability of ventricular repolarization, exhibit a reduced complexity provoked by transient myocardial ischemia.
Myocardial ischemia may lead to significant changes in autonomic control of heart rate (HR) affecting its variability and alter beat-to-beat ventricular repolarization periods. We hypothesized that transient myocardial ischemia affects the complex dynamics of the HR and QT. The aim of this study was to assess the RR and QT interval time series complexity using Higuchi's fractal dimension (HFD) during prolonged balloon occlusion of one of the major coronary arteries.
Autonomic nervous system (ANS) is governed by complex interactions arising from feedback loops of nonlinear systems that operate over a wide range of temporal and spatial scales, enabling the organism to adapt to stress, metabolic changes and diseases. This study is aimed to assess multifractal and nonlinear characteristics of the ANS during ischemic events provoked by a prolonged percutaneous coronary intervention (PCI) procedure. Eighty-seven patients from the STAFF III database were used. Patients were classified into 2 groups: (1) with prior myocardial infarction (MI) and (2) without MI (noMI). R–R signals during three 3-min stages of the procedures were analyzed using multifractal and surrogate data techniques. Multifractal indices increased significantly from the pre-inflation stage to the post-deflation stage. These variations were more marked for the noMI group. Multifractal changes significantly correlated with both the decreased parasympathetic and the increased sympathetic modulations accounted by classical linear indices. Multifractal measures resulted to be a more powerful indicator than linear HRV indices in quantifying the ischemia-induced changes. Right coronary artery (RCA) occlusions provoke greater multifractal reactions throughout the PCI procedure. Our findings suggest reduced complex multifractal and nonlinear reactions of ANS activity in patients with prior MI in comparison to the noMI group, possibly due to degradation in the complexity of control mechanism of heart rate generation
Repolarization dynamics may be of increasing interest in analyzing ECG-Holter for characterization of myocardial ischemic events related to cardiac death. The quantification of the dynamics of the beat-to-beat QT interval fluctuations, representing changes in repolarization duration, may be another emerging marker of cardiac events. Based on these arguments, we propose a symbolic analysis series to quantify the dynamics of the beat-to-beat QT interval fluctuations, representing changes in repolarization duration, and the prevalence of sympathetic or parasympathetic cardiac modulation in the RR series. This analysis decomposes the series in patterns of length L=3 beat and classify them into three categories: non-variable, variable, and very variable patterns referred to as P0, P1 and P2 patterns. The present work analyses QT and RR series obtained from 24-hour ECG-Holter recordings in order to obtained patterns able to stratify high (HRG) and low risk (LRG) of suffer cardiac mortality in patients with symptomatic myocardial ischemia. Comparing LRG and HRG, results showed that pattern P0 could better quantify QT series and pattern P2 the RR series. These findings suggest a decreased cardiac vagal function with a relative increase in sympathetic cardiac modulation, and more complex pattern of ventricular repolarization in the HRG.
Gomis, P.; Caminal, P.; Vallverdu, M.; Warren, S.; Stein, P.; Wagner, G. Journal of electrocardiology Vol. 45, num. 1, p. 82-89 DOI: 10.1016/j.jelectrocard.2011.08.013 Date of publication: 2012-01 Journal article
The purpose of this study was to describe the
changes in high-frequency QRS (HF-QRS) components due to
myocardial ischemia provoked by prolonged artery occlusion
during percutaneous coronary interventions (PCI). Signalaveraged
ECGs from 69 patients were obtained during PCI
procedures and comparison of high-frequency components of
the QRS at different temporal regions and frequency
bandwidth were performed. Continuous wavelet transform was
applied to estimate the energy contents over the studied timefrequency
regions. Seven frequency bands from 50 to 300 Hz,
with bandwidth = 100 Hz were considered. The sum of all 12
leads energy decreased significantly (p < 0.001) from pre-PCI
to PCI during both second half and total QRS complex in all
frequency bands, but the main effect was found in the 200-300
Hz band. The energy changes were more marked toward
higher frequency bands. The second half of QRS complex was
more sensitive to changes due to myocardial ischemia.
Dumont, J.; Hernández, A.; Gomis, P.; Carrault, G. Colloque sur le Traitement du Signal et des Images p. 5521-5524 DOI: DOI : 10.4267/2042/28932 Presentation's date: 2009-09-09 Presentation of work at congresses
A new method for myocardial ischemia detection is proposed in this communication. The originality of this method relies on the
consideration of the dynamics of times series extracted from the ECG whereas traditionnal methods are simply based on static measures. After the extraction of a feature vector, the dynamics are caracterised with an Hidden Semi-Markovian Model (HSMM). The ischemic detector uses
a reference HSMM and an ischemic HSMM and then compare the likelihood of the time series. Results obtained with PTCA (percutaneous transluminal coronary angioplasty) records of the STAFF3 database show a very good detection rate (96% of sensibility and 80% of specificity).
Magrans, R.; Gomis, P.; Caminal, P.; Wagner, G. IEEE Engineering in Medicine and Biology Society p. 1808-1811 DOI: 10.1109/IEMBS.2009.5333930 Presentation's date: 2009-09-03 Presentation of work at congresses
We assess the autonomic nervous system response during prolonged percutaneous transluminal coronary angioplasty (PTCA) by heart rate variability analysis using
multifractal indices. These indices are also used to evaluate the effects of the PTCA at different arteries. The indices augmented significantly during transient ischemia and
reperfusion periods indicating an increase of multifractal degree and a decrease of the long-range dependence on heartbeat fluctuations. This indicates that significant
multifractal complex reactions of autonomic control of the heart rate occurred during coronary artery occlusions.