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Electrocardiographic imaging: New applications and new inverse methodologyOster, Howard Steven January 1995 (has links)
No description available.
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The Relationship Between Seroreactivity to Trypanosoma Cruzi and Electrocardiographic Abnormalities in Two Endemic Areas For Chagas Disease in GuatemalaGramajo-rodriguez, Rodrigo Antonio 01 January 2011 (has links) (PDF)
Chagas disease caused by the protozoan Trypanosoma cruzi is the leading cause of heart disease in Latin America. After an acute phase that typically includes few symptoms, a chronic cardiac phase occurs for many infected individuals. The progression to chronic heart disease is not fully understood in Guatemala. The objective of this study was to determine the association between T. cruzi infection and progression to Chagas heart disease in Guatemala and determine if the relation is modified according to vector predominance.
Using a community-based cross-sectional approach, 813 individuals from two areas of Guatemala were included in the study: 478 (58.8%) from Jalapa and 335 (41.2%) from Chiquimula. Data including serologic evaluation, electrocardiography (ECGs) and demographics were collected to compare the degree of detectable cardiac abnormalities in infected and uninfected individuals.
Overall, T. cruzi seroprevalence was 28.8%, 247 (30.4%) presented an abnormal electrocardiography and 79 (9.7%) were diagnosed as Chagas heart disease. Seroreactivity was statistically (p-value<0.05) associated with abnormal ECG, Chagas heart disease, community, age, occupation, time living in the area, knowledge of the vector, ventricular condition defects and ST-T waves changes. The age and sex-adjusted association between a positive seroreactive and abnormal ECG was higher in Jalapa OR=2.0 (CI95% 1.2, 3.1) than in Chiquimula OR=1.2 (CI95% 0.9, 1.8).
These results show the high Chagas-cardiac burden in this population and support the idea that the vector predominance plays an importance role in the association and that this should be taken into account in the design of intervention for vector control.
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Electrocardiographic Imaging (ECGI): Application of An Iterative Method And Validation In HumansRamanathan, Charulatha 05 April 2004 (has links)
No description available.
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Uso de hialuronidase 75 UTR/ml concomitante à mepivacaína associada à epinefrina em bloqueio do nervo alveolar inferior: estudo hemodinâmico e eletrocardiográfico / Use of hyaluronidase 75 TRU/ml concomitantly with mepivacaine associated epinephrine and inferior alveolar nerve block: hemodynamic and electrocardiographic studyTornelli, Mauricio José 19 January 2012 (has links)
Dentre os adjuvantes para os anestésicos locais (AL), a enzima hialuronidase tem seu uso consagrado na anestesia oftalmológica como difusor do AL. É utilizada para melhorar a eficácia clínica e prolongar a anestesia como alternativa aos anestésicos locais de longa duração em pacientes com comprometimento sistêmico. Este estudo duplo-cego e controlado avaliou os efeitos cardiovasculares induzidos por 3,6 ml de anestésico local (AL) cloridrato de mepivacaína 2% com epinefrina 1:100.000 concomitantemente à hialuronidase 75 UTR/ml ou placebo (veiculo), em bloqueio do nervo alveolar inferior para realização de cirurgia de terceiros molares inferiores bilaterais e simétricos, em 20 pacientes. Foi realizada apenas uma cirurgia por consulta, no mesmo horário e operador. Os parâmetros cardiovasculares pressão sistólica (PS), diastólica (PD), média (PM) e freqüência cardíaca (FC) foram monitorados através de método oscilométrico e fotopletismográfico, em 10 etapas clínicas. Os registros eletrocardiográficos (ECG) das 12 derivações foram obtidos em 4 etapas: (T1) basal; (T2) anestésico local; (T3), 5 min. do AL; (T4) após a cirurgia. Foram avaliadas no ECG as seguintes variáveis: frequência cardíaca, duração do intervalo PR , duração do complexo QRS, duração do segmento QT corrigido. A hialuronidase injetada concomitantemente com o anestésico local (AL) não induziu alterações nas PS, PD, PM e FC (p>0,01, n=20) comparada ao placebo, mas houve alteração (p>0,01) na PS e FC na interação tempo x fármacos. Não foram observadas alterações eletrocardiográficas (n=18) consideradas de importância clínica como: infradesnivelamento do segmento ST, supradesnivelamento do segmento ST, extrassístoles de complexo QRS largo e extrassístoles de complexo QRS estreito. O uso do anestésico local injetado concomitante à hialuronidase 75 UTR/ml mostrou-se seguro para esta dose e via de administração. / Among the adjuvants to local anesthetics (LA), the enzyme hyaluronidase has its consecrated in ophthalmic anesthesia as a diffuser (spread) of the LA. It is used to improve the clinical efficacy and prolong anesthesia as an alternative to long lasting local anesthetics in patients with systemic involvement. This double-blind, controlled trial evaluated the cardiovascular effects induced by 3.6 ml of local anesthetic (LA) 2% mepivacaine hydrochloride with epinephrine 1:100,000 concomitantly with hyaluronidase 75 TRU/ml or placebo (vehicle) in blocking inferior alveolar nerve for performing third molar surgery bilateral and symmetrical in 20 patients. Surgery was performed only one by appointment, at the same time and operator. The cardiovascular parameters systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP) and heart rate (HR) were monitored using the oscillometric method and photoplethysmography in 10 clinical stages. Records electrocardiographic (ECG) of 12 leads were obtained in four steps: (T1) baseline, (T2) local anesthetic, (T3), 5 mim AL, (T4) after surgery. ECG were evaluated in the following variables: heart rate, duration of PR segment, duration of the complex QRS, duration of the corrected QT interval. Hyaluronidase injected concomitantly with local anesthetic did not induce changes in the SBP, DBP, MBP, and HR (p> 0.01, n = 20) compared to placebo, except in the interaction between steps and drugs (p<0.01) for SBP and HR. There were no ECG changes (n = 18) considered of clinical importance as ST segment depression, ST segment elevation, extrasystoles wide QRS complex and extrasystoles of narrow QRS complex. The use of local anesthetic injected concomitantly with hyaluronidase 75 TRU/ml was safe at this dose and route of administration.
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Mathematical models and simulation studies of effects of heterogeneity and loss of channel function on egg signal and cardiac vulnerability / Μαθηματικά μοντέλα και μελέτες εξομοίωσης των επιπτώσεων ετερογένειας και απώλειας των δίαυλων στο ΗΚΓ και στην καρδιακή ευπάθειαKapela, Adam 26 June 2007 (has links)
Mathematical models and simulation studies of the electrical function of the heart contribute significantly to better understanding and treatment of cardiac arrhythmias. Although great progress has been made in this area, particularly in single cell models, many problems related to macroscopic electrical behavior of the heart remain unsolved or require reevaluation as new experimental data appear. The scope of this thesis is the development of mathematical models of effects of heterogeneity and loss of channel function on electrocardiographic (ECG) signal and cardiac vulnerability. Our studies contribute to better arrhythmia understanding, prediction and prevention. In the first study theoretical body-surface potentials were computed from single, branching and tortuous strands of the Luo-Rudy model cells, representing different areas of an infarct scar. When action potential (AP) propagation either in longitudinal or transverse direction was slow (3-12 cm/s), the depolarization signals contained high-frequency (100- 300 Hz) oscillations. The frequencies were related to macroscopic propagation velocity and strand architecture by simple formulas. Next, we proposed a mathematical model of the QRS-complex that simulates unstable activation wavefront. It combines signals from different strands with small timing fluctuations relative to a large repetitive QRS-like waveform and can account for dynamic changes of real arrhythmogenic micropotentials. Variance spectrum of wavelet coefficients calculated from the composite QRS-complex contained the high frequencies of the individual abnormal signals. We concluded that slow AP propagation through fibrotic regions after myocardial infarction is a source of high-frequency arrhythmogenic components that increase beat-to-beat variability of the QRS, and wavelet variance parameters can be used for ventricular tachycardia risk assessment. xv In the second study we quantify the vulnerable period (VP) in heterogeneous models of ventricular wall and its modulation by loss of cardiac sodium channel function (NaLOF). According to several articles, NaLOF prolongs the VP and, therefore, increases risk of reentrant arrhythmias, but the studies used uniform models neglecting spatial variation of action potential duration (APD). Here, we introduce physiological transmural heterogeneity into one-dimensional cables of the Luo-Rudy model cells. We propose a generalized formula for the VP and describe new phenomena pertaining to the VP that are not present in homogeneous excitable media. We conclude that realistic models of cardiac vulnerability should take into account spatial variations of cellular refractoriness. It reveals several new qualitative and quantitative aspects of the VP and the modulation of the VP by NaLOF differs significantly in heterogeneous and homogeneous models. Finally we examine proarrhythmic potential of E-4031, a class III antiarrhythmic agent that blocks selectively rapid potassium current (IKr), during ischemia. Effective refractory periods (ERP) and action potential durations of the Luo-Rudy dynamic model cell were measured for normal and ischemic conditions, after IKr block and at different basic cycle lengths (BCL). Acute ischemia is introduced into the model by hyperkalemia, acidosis and anoxia. The IKr block caused reverse use-dependent prolongation of APD and ERP for normal and the ischemic conditions. Differences in APD and ERP between normal and acutely ischemic cells increased after the IKr block for all BCLs. We conclude that E-4031 has the potential to amplify electrophysiologic heterogeneity between normal and ischemic cardiac tissue that underlies some serious ventricular arrhythmias. This increased dispersion can cancel out the poor antiarrhythmic effect of AP and ERP prolongation at fast heart rates. / Τα µαθηµατικά µοντέλα και οι µελέτες εξοµοίωσης της ηλεκτρικής δραστηριότητας της καρδιάς συνεισφέρουν σηµαντικά στην καλύτερη κατανόηση και θεραπευτική αγωγή της καρδιακής αρρυθµίας. Παρόλο που έχει πραγµατοποιηθεί µεγάλη πρόοδος στον τοµέα αυτό, ειδικά σε µοντέλα µεµονωµένων κυττάρων, πολλά προβλήµατα που σχετίζονται µε την µακροσκοπική ηλεκτρική δραστηριότητα ακόµη παραµένουν άλυτα ή χρειάζονται επαναξιολόγηση καθώς νέα πειραµατικά δεδοµένα συνεχώς εµφανίζονται. Ο σκοπός αυτής της διατριβής είναι η ανάπτυξη µαθηµατικών µοντέλων µελέτης των επιπτώσεων ετερογένειας και απώλειας της καναλικής λειτουργίας στο Ηλεκτροκαρδιογράφηµα (ΗΚΓ) και στην καρδιακή ευπάθεια. Οι µελέτες µας συνεισφέρουν στην καλύτερη κατανόηση, πρόβλεψη και πρόληψη της καρδιακής αρρυθµίας. Στην πρώτη µελέτη, υπολογίζονται θεωρητικά δυναµικά επιφανείας του σώµατος από µεµονωµένα, διακλαδωτά και µε ελικοειδή µορφή πλέγµατα των κύτταρων βασισµένα στο µοντέλο Luo-Rudy, τα οποία αντιπροσωπεύουν διαφορετικές περιοχές µε ουλή εµφράγµατος. Στις περιπτώσεις αργής µετάδοσης του δυναµικού δράσεως (∆∆) είτε κατά την διαµήκη ή εγκάρσια κατεύθυνση (3-12cm/s), τα σήµατα εκπόλωσης εµπεριείχαν ταλαντώσεις υψηλής συχνότητας (100- 300Hz). Οι συχνότητες συσχετίστηκαν µε την µακροσκοπική ταχύτητα µετάδοσης και µε την αρχιτεκτονική του πλέγµατος µε τη χρήση απλών µοντέλων. Κατόπιν, προτείνουµε ένα µαθηµατικό µοντέλο για το σύµπλεγµα-QRS το οποίο εξοµοιώνει κυµατοµορφές διάδοσης µε µη σταθερή µορφή. Το µοντέλο συνδυάζει σήµατα από διαφορετικά πλέγµατα µε µικρές διακυµάνσεις σε σχέση προς µία µεγάλη επαναληπτική κυµατοµορφή τύπου QRS και µπορεί να λάβει υπόψη τις δυναµικές µεταβολές πραγµατικών µικρό-δυναµικών αρρυθµογενών περιοχών Το φάσµα των συντελεστών κυµατίου (wavelet) το οποίο υπολογίστηκε από το σύνθετο σύµπλεγµα-QRS, εµπεριείχε τις υψηλές συχνότητες από τα µεµονωµένα ανώµαλα σήµατα. Συµπεράναµε ότι η αργή µετάδοση του ∆∆ δια µέσου ινωµατωειδών περιοχών µετά από έµφραγµα µυοκαρδίου, αποτελεί πηγή αρρυθµογενικών συνιστωσών υψηλής συχνότητας, οι οποίες αυξάνουν την µεταβλητότητα από παλµό σε παλµό του συµπλέγµατος QRS, και οι παράµετρες µεταβλητότητας των συντελεστών κυµατίου µπορούν να χρησιµοποιηθούν για την αποτίµηση της επικινδυνότητας κοιλιακής ταχυκαρδίας. ix Στην δεύτερη µελέτη, ποσοτικοποιούµε την περίοδο ευπάθειας (ΠΕ) σε ετερογενή µοντέλα του κοιλιακού τοιχώµατος και την διαµόρφωση του κατά την απώλεια λειτουργίας του καρδιακού καναλιού νατρίου (NaLOF). Σύµφωνα µε διάφορα επιστηµονικά άρθρα, το NaLOF επεκτείνει την ΠΕ και, εποµένως, αυξάνει την επικινδυνότητα επαναεισερχόµενων αρρυθµιών, αλλά οι µελέτες αυτές χρησιµοποίησαν οµοιογενή µοντέλα αγνοώντας την χωρική µεταβλητότητα της διάρκειας των δυναµικών δράσεως (∆∆). Σε αυτή την µελέτη, εισάγουµε την φυσιολογική διατοιχωµατική ετερογένεια σε µοντέλα κυττάρων Luo-Rudy τα οποία είναι διατεταγµένα σε αλυσίδες µίας διαστάσεως. Προτείνουµε ένα γενικό µοντέλο για την ΠΕ και περιγράφουµε νέα φαινόµενα που χαρακτηρίζουν την ΠΕ τα οποία δεν υπάρχουν στην περίπτωση οµογενούς διεγέρσιµου µέσου. Καταλήγουµε, ότι τα ρεαλιστικά µοντέλα της καρδιακής ευπάθειας θα πρέπει να λαµβάνουν υπόψη τις χωρικές µεταβολές της ανερέθιστης περίοδου. Αποκαλύπτονται νέες ποιοτικές και ποσοτικές όψεις της ΠΕ και η µεταβολή της ΠΕ από το NaLOF διαφέρει σηµαντικά σε οµογενή και ετερογενή µοντέλα. Τέλος, εξετάζουµε τη προαρρυθµική δράση του E-4031, που είναι ένα αντιαρρυθµικό φάρµακο οµάδας ΙΙΙ που µπλοκάρει επιλεκτικά του ταχέως ρεύµατος καλίου (IKr) κατά την ισχαιµία. Οι σχετικές ανερέθιστες περίοδοι (ΣΑΠ) και η διάρκεια των δυναµικών δράσεως του δυναµικού µοντέλου κυττάρων Luo-Rudy µετρήθηκαν για φυσιολογικές και ισχαιµικές συνθήκες, µετά από το µπλοκάρισµα του IKr και για διαφορετικά βασικά µήκη κύκλων (ΒΜΚ). Η περίπτωση οξείας ισχαιµίας εισήχθηκε στο µοντέλο µε υπερκαλιαιµία, οξέωση και ανοξαιµία. Το µπλοκ του IKr προκάλεσε αντίστροφη επιµήκυνση εξαρτώµενη από τη χρήση του ∆∆ και ΣΑΠ για φυσιολογικές και ισχαιµικές συνθήκες. Η διαφορές µεταξύ του ∆∆ και ΣΑΠ µεταξύ φυσιολογικού και µε οξεία ισχαιµία κυττάρων αυξήθηκαν µετά το µπλοκ του IKr για όλα τα BMK. Καταλήγουµε στο συµπέρασµα ότι το E-4031 έχει την δυνατότητα να ενισχύει την ηλεκτροφυσιολογική ετερογένεια µεταξύ του φυσιολογικού και του ισχαιµικού καρδιακού ιστού που αποτελεί την βασική εξήγηση µερικών σοβαρών κοιλιακών αρρυθµιών. Αυτή η αυξηµένη διασπορά µπορεί να ακυρώσει την φτωχή αντιαρρυθµιακή επίδραση της επιµήκυνσης του ∆∆ και ΣΑΠ σε αυξηµένους καρδιακούς ρυθµούς.
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Uso de hialuronidase 75 UTR/ml concomitante à mepivacaína associada à epinefrina em bloqueio do nervo alveolar inferior: estudo hemodinâmico e eletrocardiográfico / Use of hyaluronidase 75 TRU/ml concomitantly with mepivacaine associated epinephrine and inferior alveolar nerve block: hemodynamic and electrocardiographic studyMauricio José Tornelli 19 January 2012 (has links)
Dentre os adjuvantes para os anestésicos locais (AL), a enzima hialuronidase tem seu uso consagrado na anestesia oftalmológica como difusor do AL. É utilizada para melhorar a eficácia clínica e prolongar a anestesia como alternativa aos anestésicos locais de longa duração em pacientes com comprometimento sistêmico. Este estudo duplo-cego e controlado avaliou os efeitos cardiovasculares induzidos por 3,6 ml de anestésico local (AL) cloridrato de mepivacaína 2% com epinefrina 1:100.000 concomitantemente à hialuronidase 75 UTR/ml ou placebo (veiculo), em bloqueio do nervo alveolar inferior para realização de cirurgia de terceiros molares inferiores bilaterais e simétricos, em 20 pacientes. Foi realizada apenas uma cirurgia por consulta, no mesmo horário e operador. Os parâmetros cardiovasculares pressão sistólica (PS), diastólica (PD), média (PM) e freqüência cardíaca (FC) foram monitorados através de método oscilométrico e fotopletismográfico, em 10 etapas clínicas. Os registros eletrocardiográficos (ECG) das 12 derivações foram obtidos em 4 etapas: (T1) basal; (T2) anestésico local; (T3), 5 min. do AL; (T4) após a cirurgia. Foram avaliadas no ECG as seguintes variáveis: frequência cardíaca, duração do intervalo PR , duração do complexo QRS, duração do segmento QT corrigido. A hialuronidase injetada concomitantemente com o anestésico local (AL) não induziu alterações nas PS, PD, PM e FC (p>0,01, n=20) comparada ao placebo, mas houve alteração (p>0,01) na PS e FC na interação tempo x fármacos. Não foram observadas alterações eletrocardiográficas (n=18) consideradas de importância clínica como: infradesnivelamento do segmento ST, supradesnivelamento do segmento ST, extrassístoles de complexo QRS largo e extrassístoles de complexo QRS estreito. O uso do anestésico local injetado concomitante à hialuronidase 75 UTR/ml mostrou-se seguro para esta dose e via de administração. / Among the adjuvants to local anesthetics (LA), the enzyme hyaluronidase has its consecrated in ophthalmic anesthesia as a diffuser (spread) of the LA. It is used to improve the clinical efficacy and prolong anesthesia as an alternative to long lasting local anesthetics in patients with systemic involvement. This double-blind, controlled trial evaluated the cardiovascular effects induced by 3.6 ml of local anesthetic (LA) 2% mepivacaine hydrochloride with epinephrine 1:100,000 concomitantly with hyaluronidase 75 TRU/ml or placebo (vehicle) in blocking inferior alveolar nerve for performing third molar surgery bilateral and symmetrical in 20 patients. Surgery was performed only one by appointment, at the same time and operator. The cardiovascular parameters systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP) and heart rate (HR) were monitored using the oscillometric method and photoplethysmography in 10 clinical stages. Records electrocardiographic (ECG) of 12 leads were obtained in four steps: (T1) baseline, (T2) local anesthetic, (T3), 5 mim AL, (T4) after surgery. ECG were evaluated in the following variables: heart rate, duration of PR segment, duration of the complex QRS, duration of the corrected QT interval. Hyaluronidase injected concomitantly with local anesthetic did not induce changes in the SBP, DBP, MBP, and HR (p> 0.01, n = 20) compared to placebo, except in the interaction between steps and drugs (p<0.01) for SBP and HR. There were no ECG changes (n = 18) considered of clinical importance as ST segment depression, ST segment elevation, extrasystoles wide QRS complex and extrasystoles of narrow QRS complex. The use of local anesthetic injected concomitantly with hyaluronidase 75 TRU/ml was safe at this dose and route of administration.
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AvaliaÃÃo da resposta eletrocardiogrÃfica e sorolÃgica ao tratamento com benzonidazol em pacientes na fase crÃnica da doenÃa de Chagas / Electrocardiographic and serological evaluation to treatment with benznidazole in chronic Chagas disease patientsMÃnica Coelho Andrade 12 March 2013 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A doenÃa de Chagas (DC) à uma patologia de natureza endÃmica, causada pelo protozoÃrio Trypanosoma cruzi, com pronunciada relevÃncia entre as doenÃas cardÃacas. Foi descrita oficialmente em 1909 e mesmo apÃs mais de um sÃculo de sua descoberta ainda representa um problema de saÃde pÃblica. O objetivo deste trabalho foi avaliar a efetividade da quimioterapia com Benzonidazol (Bz) em pacientes chagÃsicos crÃnicos atravÃs de anÃlise sorolÃgica e eletrocardiogrÃfica. Trata-se de um estudo prospectivo nÃo concorrente e concorrente, onde os pacientes foram acompanhados sorologicamente uma vez ao ano depois do tratamento, a partir de 2005, 2006 ou 2007 (antes do tratamento) atà 2011. A avaliaÃÃo eletrocardiogrÃfica foi realizada no inÃcio (2005 a 2007) e final da pesquisa (2011). Os pacientes foram tratados com Bz na dosagem de 5mg/Kg/dia em duas a trÃs tomadas diÃrias durante 60 dias. A anÃlise sorolÃgica foi realizada atravÃs das tÃcnicas de ELISA (Ensaio ImunoenzimÃtico) e IFI (ImunofluorescÃncia indireta). A avaliaÃÃo eletrocardiogrÃfica foi feita atravÃs dos eletrocardiogramas (ECG) realizados no Hospital UniversitÃrio Walter CantÃdio e disponÃveis nos prontuÃrios dos pacientes. Foram acompanhados 31 pacientes, 20 (64,5%) do sexo masculino e 11 (35,5%) do feminino, de 25 a 64 anos, dos quais 51,6% (16/31) cursaram o primeiro grau incompleto e 22,6% (7/31) eram agricultores. A anÃlise sorolÃgica atravÃs do teste ELISA demonstrou queda significativa da densidade Ãptica das amostras coletadas antes (2005 a 2007) em relaÃÃo Ãs amostras pÃs-tratamento (2011). Com relaÃÃo à IFI, os pacientes mantiveram-se inalterados durante o segmento (variaÃÃo de no mÃximo uma diluiÃÃo entre a amostra basal e 2011). No que diz respeito à avaliaÃÃo eletrocardiogrÃfica, 76,2% (16/21) apresentaram manutenÃÃo dos laudos eletrocardiogrÃficos ao longo do estudo, com exceÃÃo de cinco casos. Um dos pacientes excluÃdo da anÃlise eletrocardiogrÃfica (nÃo existia ECG realizado em 2011) necessitou de um implante de desfibrilador ao longo do acompanhamento (2010). Em conclusÃo, pode-se afirmar que embora o Bz apresente efetividade limitada em pacientes na fase crÃnica da DC, este estudo demonstrou um efeito benÃfico do medicamento na maioria dos pacientes acompanhados, jà que a maioria destes apresentou manutenÃÃo dos laudos eletrocardiogrÃficos e a sorologia mostrou uma tendÃncia à queda. Entretanto, faz-se necessÃrio um perÃodo maior de segmento, jà que o tempo de acompanhamento deste estudo (5 a 7 anos) à considerado curto para pacientes na fase crÃnica da doenÃa. / Chagas disease (CD) is a pathology of endemic nature, caused by the protozoan Trypanosoma cruzi, with pronounced relevance between heart disease. It was officially described in 1909 and even after more than a century of its discovery is still a public health problem. The aim of this study was to evaluate the effectiveness of chemotherapy with Benznidazole (Bz) in patients with chronic Chagas disease by serological analysis and electrocardiography. This is a prospective non-concurrent and concurrent study, where patients were followed serologically once a year after treatment, from 2005, 2006 or 2007 (before treatment) until 2011. The electrocardiographic evaluation was performed at baseline (2005-2007) and end of the study (2011). The patients were treated with Bz in dose of 5mg/kg/day in two to three daily doses for 60 days. The serological analysis was conducted, through the techniques of ELISA (enzyme immunoassay) and IIF (indirect immunofluorescence). The electrocardiographic evaluation was performed at the University Hospital Walter CantÃdio through the electrocardiograms (ECG) available in patient charts. This study followed 31 patients, 20 (64,5%) male and 11 (35,5%) female, from 25 to 64 years, where 51.6% (16/31) did not finish high school and 22,6% (7/31) were farmers. Serological analysis by ELISA demonstrated a significant decrease in the optical density of the samples collected before (2005 to 2007) when compared with the samples after treatment (2011). Now with regard to IIF, patients remained unchanged during the segment (variation in a maximum of a dilution of the sample between baseline and 2011). Regarding the electrocardiographic evaluation, 76.2% (16/21) showed maintenance of electrocardiographic reports throughout the study, with the exception of cinco cases. One patient was excluded from analysis electrocardiographic (there wasnât ECG performed in 2011) required a defibrillator implantation during follow-up (2010). In conclusion, one can say that although Bz presents limited effectiveness in patients in the chronic phase of CD, this study demonstrated a beneficial effect of the drug in most followed patients, as the majority of these reports showed maintenance of electrocardiographic and serology showed a downward trend. However, it is necessary a longer segment, since the follow-up period of this study (5-7 years) is considered short for patients in the chronic phase of the disease.
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Diagnosis of acute coronary occlusion using computed electrocardiographic imaging based on the 12-lead electrocardiogram, in comparison with ST- elevation myocardial infarction criteriaAl-Mashat, Mariam January 2012 (has links)
Introduction: Computed electrocardiographic imaging (CEI) is a method that uses ST- segment deviations from the 12-lead electrocardiogram (ECG) and has been tested on a small number of patients.Aim: To extend the testing material of the CEI method and deduce a threshold using ECGs recorded pre- and during acute occlusion. The performance of the CEI and ST elevation myocardial infarction (STEMI) criteria will be compared. Method: Two CEI images were generated from each of 99 patients before and during complete occlusion in the left anterior descending (LAD), right coronary artery (RCA) and left circumflex coronary artery (LCx). Result: The sensitivity and specificity of STEMI criteria was 61% and 96% respectively for the whole occlusion group. The sensitivities and specificities were 74 %, 97% (LAD); 60%, 94% (RCA); 35%, 100% (LCx) respectively, for STEMI criteria. A threshold of 998 units was deduced from the CEI method. Conclusion: The CEI method has similar diagnostic performance of an occlusion as STEMI criteria.
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Non-invasive identification of atrial fibrillation driversRodrigo Bort, Miguel 19 December 2016 (has links)
Atrial fibrillation (AF) is one of the most common cardiac arrhythmias. Nowadays the fibrillatory process is known to be provoked by the high-frequency reentrant activity of certain atrial regions that propagates the fibrillatory activity to the rest of the atrial tissue, and the electrical isolation of these key regions has demonstrated its effectiveness in terminating the fibrillatory process.
The location of the dominant regions represents a major challenge in the diagnosis and treatment of this arrhythmia. With the aim to detect and locate the fibrillatory sources prior to surgical procedure, non-invasive methods have been developed such as body surface electrical mapping (BSPM) which allows to record with high spatial resolution the electrical activity on the torso surface or the electrocardiographic imaging (ECGI) which allows to non-invasively reconstruct the electrical activity in the atrial surface. Given the novelty of these systems, both technologies suffer from a lack of scientific knowledge about the physical and technical mechanisms that support their operation. Therefore, the aim of this thesis is to increase that knowledge, as well as studying the effectiveness of these technologies for the localization of dominant regions in patients with AF.
First, it has been shown that BSPM systems are able to noninvasively identify atrial rotors by recognizing surface rotors after band-pass filtering. Furthermore, the position of such surface rotors is related to the atrial rotor location, allowing the distinction between left or right atrial rotors. Moreover, it has been found that the surface electrical maps in AF suffer a spatial smoothing effect by the torso conductor volume, so the surface electrical activity can be studied with a relatively small number of electrodes. Specifically, it has been seen that 12 uniformly distributed electrodes are sufficient for the correct identification of atrial dominant frequencies, while at least 32 leads are needed for non-invasive identification of atrial rotors.
Secondly, the effect of narrowband filtering on the effectiveness of the location of reentrant patterns was studied. It has been found that this procedure allows isolating the reentrant electrical activity caused by the rotor, increasing the detection rate for both invasive and surface maps. However, the spatial smoothing caused by the regularization of the ECGI added to the temporal filtering causes a large increase in the spurious reentrant activity, making it difficult to detect real reentrant patterns. However, it has been found that maps provided by the ECGI without temporal filtering allow the correct detection of reentrant activity, so narrowband filtering should be applied for intracavitary or surface signal only.
Finally, we studied the stability of the markers used to detect dominant regions in ECGI, such as frequency maps or the rotor presence. It has been found that in the presence of alterations in the conditions of the inverse problem, such as electrical or geometrical noise, these markers are significantly more stable than the ECGI signal morphology from which they are extracted. In addition, a new methodology for error reduction in the atrial spatial location based on the curvature of the curve L has been proposed.
The results presented in this thesis showed that BSPM and ECGI systems allows to non-invasively locate the presence of high-frequency rotors, responsible for the maintenance of AF. This detection has been proven to be unambiguous and robust, and the physical and technical mechanisms that support this behavior have been studied. These results indicate that both non-invasive systems provide information of great clinical value in the treatment of AF, so their use can be helpful for selecting and planning atrial ablation procedures. / La fibrilación auricular (FA) es una de las arritmias cardiacas más frecuentes. Hoy en día se sabe que el proceso fibrilatorio está provocado por la actividad reentrante a alta frecuencia de ciertas regiones auriculares que propagan la actividad fibrilatoria en el resto del tejido auricular, y se ha demostrado que el aislamiento eléctrico de estas regiones dominantes permite detener el proceso fibrilatorio.
La localización de las regiones dominantes supone un gran reto en el diagnóstico y tratamiento de la FA. Con el objetivo de poder localizar las fuentes fibrilatorias con anterioridad al procedimiento quirúrgico, se han desarrollado métodos no invasivos como la cartografía eléctrica de superficie (CES) que registra con gran resolución espacial la actividad eléctrica en la superficie del torso o la electrocardiografía por imagen (ECGI) que permite reconstruir la actividad eléctrica en la superficie auricular. Dada la novedad de estos sistemas, existe una falta de conocimiento científico sobre los mecanismos físicos y técnicos que sustentan su funcionamiento. Por lo tanto, el objetivo de esta tesis es aumentar dicho conocimiento, así como estudiar la eficacia de ambas tecnologías para la localización de regiones dominantes en pacientes con FA.
En primer lugar, ha visto que los sistemas CES permiten identificar rotores auriculares mediante el reconocimiento de rotores superficiales tras el filtrado en banda estrecha. Además, la posición de los rotores superficiales está relacionada con la localización de dichos rotores, permitiendo la distinción entre rotores de aurícula derecha o izquierda. Por otra parte, se ha visto que los mapas eléctricos superficiales durante FA sufren una gran suavizado espacial por el efecto del volumen conductor del torso, lo que permite que la actividad eléctrica superficial pueda ser estudiada con un número relativamente reducido de electrodos. Concretamente, se ha visto que 12 electrodos uniformemente distribuidos son suficientes para una correcta identificación de frecuencias dominantes, mientras que son necesarios al menos 32 para una correcta identificación de rotores auriculares.
Por otra parte, también se ha estudiado el efecto del filtrado en banda estrecha sobre la eficacia de la localización de patrones reentrantes. Así, se ha visto que este procedimiento permite aislar la actividad eléctrica reentrante provocada por el rotor, aumentando la tasa de detección tanto para señal obtenida de manera invasiva como para los mapas superficiales. No obstante, este filtrado temporal sobre la señal de ECGI provoca un gran aumento de la actividad reentrante espúrea que dificulta la detección de patrones reentrantes reales. Sin embargo, los mapas ECGI sin filtrado temporal permiten la detección correcta de la actividad reentrante, por lo el filtrado debería ser aplicado únicamente para señal intracavitaria o superficial.
Por último, se ha estudiado la estabilidad de los marcadores utilizados en ECGI para detectar regiones dominantes, como son los mapas de frecuencia o la presencia de rotores. Se ha visto que en presencia de alteraciones en las condiciones del problema inverso, como ruido eléctrico o geométrico, estos marcadores son significativamente más estables que la morfología de la propia señal ECGI. Además, se ha propuesto una nueva metodología para la reducción del error en la localización espacial de la aurícula basado en la curvatura de la curva L.
Los resultados presentados en esta tesis revelan que los sistemas de CES y ECGI permiten localizar de manera no invasiva la presencia de rotores de alta frecuencia. Esta detección es univoca y robusta, y se han estudiado los mecanismos físicos y técnicos que sustentan dicho comportamiento. Estos resultados indican que ambos sistemas no invasivos proporcionan información de gran valor clínico en el tratamiento de la FA, por lo que su uso puede ser de gran ayuda para la selección y planificaci / La fibril·lació auricular (FA) és una de les arítmies cardíaques més freqüents. Hui en dia es sabut que el procés fibrilatori està provocat per l'activitat reentrant de certes regions auriculars que propaguen l'activitat fibril·latoria a la resta del teixit auricular, i s'ha demostrat que l'aïllament elèctric d'aquestes regions dominants permet aturar el procés fibrilatori.
La localització de les regions dominants suposa un gran repte en el diagnòstic i tractament d'aquesta arítmia. Amb l'objectiu de poder localitzar fonts fibril·latories amb anterioritat al procediment quirúrgic s'han desenvolupat mètodes no invasius com la cartografia elèctrica de superfície (CES) que registra amb gran resolució espacial l'activitat elèctrica en la superfície del tors o l'electrocardiografia per imatge (ECGI) que permet obtenir de manera no invasiva l'activitat elèctrica en la superfície auricular. Donada la relativa novetat d'aquests sistemes, existeix una manca de coneixement científic sobre els mecanismes físics i tècnics que sustenten el seu funcionament. Per tant, l'objectiu d'aquesta tesi és augmentar aquest coneixement, així com estudiar l'eficàcia d'aquestes tecnologies per a la localització de regions dominants en pacients amb FA.
En primer lloc, s'ha vist que els sistemes CES permeten identificar rotors auriculars mitjançant el reconeixement de rotors superficials després del filtrat en banda estreta. A més, la posició dels rotors superficials està relacionada amb la localització d'aquests rotors, permetent la distinció entre rotors de aurícula dreta o esquerra. També s'ha vist que els mapes elèctrics superficials durant FA pateixen un gran suavitzat espacial per l'efecte del volum conductor del tors, el que permet que l'activitat elèctrica superficial pugui ser estudiada amb un nombre relativament reduït d'elèctrodes. Concretament, s'ha vist que 12 elèctrodes uniformement distribuïts són suficients per a una correcta identificació de freqüències dominants auriculars, mentre que són necessaris almenys 32 per a una correcta identificació de rotors auriculars.
D'altra banda, també s'ha estudiat l'efecte del filtrat en banda estreta sobre l'eficàcia de la localització de patrons reentrants. Així, s'ha vist que aquest procediment permet aïllar l'activitat elèctrica reentrant provocada pel rotor, augmentant la taxa de detecció tant pel senyal obtingut de manera invasiva com per als mapes superficials. No obstant això, aquest filtrat temporal sobre el senyal de ECGI provoca un gran augment de l'activitat reentrant espúria que dificulta la detecció de patrons reentrants reals. A més, els mapes proporcionats per la ECGI sense filtrat temporal permeten la detecció correcta de l'activitat reentrant, per la qual cosa el filtrat hauria de ser aplicat únicament per a senyal intracavitària o superficial.
Per últim, s'ha estudiat l'estabilitat dels marcadors utilitzats en ECGI per a detectar regions auriculars dominants, com són els mapes de freqüència o la presència de rotors. S'ha vist que en presència d'alteracions en les condicions del problema invers, com soroll elèctric o geomètric, aquests marcadors són significativament més estables que la morfologia del mateix senyal ECGI. A més, s'ha proposat una nova metodologia per a la reducció de l'error en la localització espacial de l'aurícula basat en la curvatura de la corba L.
Els resultats presentats en aquesta tesi revelen que els sistemes de CES i ECGI permeten localitzar de manera no invasiva la presència de rotors d'alta freqüència. Aquesta detecció és unívoca i robusta, i s'han estudiat els mecanismes físics i tècnics que sustenten aquest comportament. Aquests resultats indiquen que els dos sistemes no invasius proporcionen informació de gran valor clínic en el tractament de la FA, pel que el seu ús pot ser de gran ajuda per a la selecció i planificació de procediments d'ablació auricular. / Rodrigo Bort, M. (2016). Non-invasive identification of atrial fibrillation drivers [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/75346 / TESIS / Premios Extraordinarios de tesis doctorales
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Estimation of Atrial Electrical Complexity during Atrial Fibrillation by Solving the Inverse Problem of ElectrocardiographyMolero Alabau, Rubén 30 October 2023 (has links)
Tesis por compendio / [ES] La fibrilación auricular (FA) es la arritmia más prevalente en el mundo y está asociada con una
elevada morbilidad, mortalidad y costes sanitarios. A pesar de los avances en opciones de
tratamiento farmacológico y terapia de ablación, el manejo de la FA todavía tiene margen de
mejora. La imagen electrocardiográfica (ECGI) se ha destacado como un prometedor método no
invasivo para evaluar la electrofisiología cardíaca y guiar las decisiones terapéuticas en casos de
fibrilación auricular. No obstante, el ECGI se enfrenta a desafíos como la necesidad de resolver
de manera precisa el denominado problema inverso de la electrocardiografía y de optimizar la
calidad de las reconstrucciones de ECGI. Además, la integración del ECGI en los procesos
clínicos rutinarios sigue siendo un reto, en gran medida debido a los costos que supone la
necesidad de imágenes cardíacas.
Por ello, los objetivos principales de esta tesis doctoral son impulsar la tecnología ECGI
mediante la determinación de sus requisitos técnicos mínimos y la mejora de las metodologías
existentes para obtener señales de ECGI precisas. Asimismo, buscamos evaluar la capacidad de
ECGI para cuantificar de forma no invasiva la complejidad de la FA. Para lograr estos objetivos,
se han llevado a cabo diversos estudios a lo largo de la tesis, desde el perfeccionamiento del ECGI
hasta la evaluación de la FA utilizando esta tecnología.
En primer lugar, se han estudiado los requisitos geométricos y de señal del problema inverso
mediante el estudio de los efectos de la densidad de la malla del torso y la distribución de
electrodos en la precisión del ECGI, lo que ha conducido a la identificación del número mínimo
de nodos y su distribución en la malla del torso. Además, hemos identificado que para obtener
señales de ECGI de alta calidad, es crucial la correcta disposición de los electrodos en la malla
del torso reconstruido. Asimismo, se ha definido y evaluado una nueva metodología de ECGI sin
necesidad de usar técnicas de imagen cardiaca. Para ello, hemos comparado métricas derivadas
del ECGI calculadas con la geometría original del corazón de los pacientes con las métricas
medidas en diferentes geometrías cardíacas. Nuestros resultados han mostrado que el ECGI sin
necesidad de imágenes cardíacas es efectivo para la correcta cuantificación y localización de los
patrones y zonas que mantienen la FA. En paralelo, hemos optimizado la regularización de
Tikhonov de orden cero actual y la optimización de la curva L para el cálculo de las señales ECGI,
investigando cómo el ruido eléctrico y las incertidumbres geométricas influyen en la
regularización. A partir de ello, propusimos un nuevo criterio que realza la precisión de las
soluciones de ECGI en escenarios con incertidumbre debido a condiciones de señal no ideales.
En segundo lugar, en esta tesis doctoral, se han llevado a cabo múltiples análisis relativos a
diferentes metodologías de procesado de señales y obtención métricas derivadas del ECGI con el
fin de caracterizar mejor el sustrato cardíaco y la actividad reentrante en las señales de ECGI de
pacientes con FA. Con el objetivo de obtener una comprensión más profunda de los mecanismos
electrofisiológicos subyacentes a la FA, hemos establecido la estrategia de filtrado óptima para
extraer patrones reentrantes específicos del paciente y métricas derivadas de señales ECGI.
Además, hemos investigado la reproducibilidad de los mapas de reentradas derivados de las
señales de ECGI y hemos encontrado su relación con el éxito de la ablación de venas pulmonares
(PVI). Nuestros resultados han mostrado que una mayor reproducibilidad en los patrones
reentrantes de FA detectados con ECGI está relacionada con el éxito de la PVI, creando una
metodología para estratificar a los pacientes con FA antes de los procedimientos de ablación. / [CA] La fibril·lació auricular (FA) és l'arrítmia més prevalent al món i està associada amb una elevada
morbiditat, mortalitat i costos sanitaris. Malgrat els avanços en opcions de tractament
farmacològic i teràpies d'ablació, el maneig de la FA encara té marge de millora. La imatge
electrocardiogràfica (ECGI) s'ha destacat com un prometedor mètode no invasiu per a avaluar
l'electrofisiologia cardíaca i guiar les decisions terapèutiques en casos de fibril·lació auricular. No
obstant això, l'ECGI s'enfronta a desafiaments com la necessitat de resoldre de manera precisa el
denominat problema invers de la electrocardiografia i d'optimitzar la qualitat de les
reconstruccions de ECGI. A més, la integració del ECGI en els processos clínics rutinaris continua
sent un repte, en gran manera a causa dels costos que suposa la necessitat d'imatges cardíaques.
Per això, els objectius principals d'aquesta tesi doctoral són impulsar la tecnologia de l'ECGI
mitjançant la determinació dels seus requisits tècnics mínims i la millora de les metodologies
existents per obtenir senyals d'ECGI precises. A més, busquem avaluar la capacitat de l'ECGI per
quantificar de forma no invasiva la complexitat de la FA. Per a aconseguir aquests objectius, s'han
dut a terme diversos estudis al llarg de la tesi, des del perfeccionament de l'ECGI fins a l'avaluació
de la FA utilitzant aquesta tecnologia.
En primer lloc, hem estudiat els requisits geomètrics i de senyal del problema invers mitjançant
l'estudi dels efectes de la densitat de la malla del tors i la distribució d'elèctrodes en la precisió de
l'ECGI, el que ha conduït a la identificació del nombre mínim de nodes i la seva distribució en la
malla del tors. A més, hem identificat que per obtindre senyals d'ECGI d'alta qualitat, és crucial
la correcta disposició dels elèctrodes en la malla del tors reconstruïda. També s'ha definit i avaluat
una nova metodologia d'ECGI sense necessitat d'utilitzar tècniques d'imatge cardíaca. Per a això,
hem comparat mètriques derivades de l'ECGI calculades amb la geometria original del cor dels
pacients amb les mètriques mesurades en diferents geometries cardíaques. Els nostres resultats
han mostrat que l'ECGI sense necessitat d'imatges cardíaques és efectiu per a la correcta quantificació
i localització dels patrons i zones que mantenen la FA. Paral·lelament, hem
optimitzat la regularització de Tikhonov d'ordre zero actual i l'optimització de la corba L per al
càlcul de les senyals d'ECGI, investigant com el soroll elèctric i les incerteses geomètriques
influeixen en la regularització. Addicionalment, vam proposar un nou criteri que reforça la
precisió de les solucions d'ECGI en escenaris amb incertesa degut a condicions de senyal no
ideals.
En segon lloc, en aquesta tesi doctoral, s'han dut a terme múltiples anàlisis relatius a diferents
metodologies de processament de senyals i obtenció de mètriques derivades de l'ECGI amb
l'objectiu de caracteritzar millor el substrat cardíac i l'activitat reentrant en les senyals d'ECGI de
pacients amb FA. Amb l'objectiu d'obtindre una comprensió més profunda dels mecanismes
electrofisiològics subjacents a la FA, hem establert l'estratègia de filtrat òptima per extreure
patrons reentrants específics del pacient i mètriques derivades de senyals ECGI. A més, hem
investigat la reproductibilitat dels mapes de reentrades derivats de les senyals d'ECGI i hem trobat
la seva relació amb l'èxit de l'ablació de venes pulmonars (PVI). Els nostres resultats han mostrat
que una major reproductibilitat en els patrons reentrants de FA detectats amb ECGI està
relacionada amb l'èxit de la PVI, creant una metodologia per estratificar els pacients amb FA abans
dels procediments d'ablació. / [EN] Atrial fibrillation (AF) is the most prevalent arrhythmia in the world and is associated with
significant morbidity, mortality, and healthcare costs. Despite advancements in pharmaceutical
treatment alternatives and ablation therapy, AF management remains suboptimal.
Electrocardiographic Imaging (ECGI) has emerged as a promising non-invasive method for
assessing cardiac electrophysiology and guiding therapeutic decisions in atrial fibrillation.
However, ECGI faces challenges in dealing with accurately resolving the ill-posed inverse
problem of electrocardiography and optimizing the quality of ECGI reconstructions. Additionally,
the integration of ECGI into clinical workflows is still a challenge that is hindered by the
associated costs arising from the need for cardiac imaging.
For this purpose, the main objectives of this PhD thesis are to advance ECGI technology by
determining the minimal technical requirements and refining existing methodologies for
acquiring accurate ECGI signals. In addition, we aim to assess the capacity of ECGI for noninvasively
quantifying AF complexity. To fulfill these objectives, several studies were developed
throughout the thesis, advancing from ECGI enhancement to AF evaluation using ECGI.
Firstly, geometric and signal requirements of the inverse problem were addressed by studying
the effects of torso mesh density and electrode distribution on ECGI accuracy, leading to the
identification of the minimal number of nodes and their distribution on the torso mesh. Besides,
we identified that the correct location of the electrodes on the reconstructed torso mesh is critical
for the accurate ECGI signal obtention. Additionally, a new methodology of imageless ECGI was
defined and assessed by comparing ECGI-derived drivers computed with the original heart
geometry of the patients to the drivers measured in different heart geometries. Our results showed
the ability of imageless ECGI to the correct quantification and location of atrial fibrillation
drivers, validating the use of ECGI without the need for cardiac imaging. Also, the current state
of-the-art zero-order Tikhonov regularization and L-curve optimization for computing ECGI
signals were improved by investigating the impact of electrical noise and geometrical
uncertainties on the regularization. We proposed a new criterion that enhances the accuracy and
reliability of ECGI solutions in situations with uncertainty from unfavorable signal conditions.
Secondly, in this PhD thesis, several analyses, signal processing methodologies, and ECGIderived
metrics were investigated to better characterize the cardiac substrate and reentrant activity
in ECGI signals from AF patients. With the objective of obtaining a deeper understanding of the
electrophysiological mechanisms underlying AF, we established the optimal filtering strategy to
extract patient-specific reentrant patterns and derived metrics in ECGI signals. Furthermore, we
investigated the reproducibility of the obtained ECGI-reentrant maps and linked them to the
success of PVI ablation. Our results showed that higher reproducibility on AF drivers detected
with ECGI is linked with the success of PVI, creating a proof-of-concept mechanism for
stratifying AF patients prior to ablation procedures. / This work was supported by: Instituto de Salud Carlos III, and Ministerio de Ciencia e
Innovación (supported by FEDER Fondo Europeo de Desarrollo Regional DIDIMO PLEC2021-
007614, ESSENCE PID2020-119364RB-I00, and RYC2018- 024346B-750), EIT Health
(Activity code SAVE-COR 220385, EIT Health is supported by EIT, a body of the European
Union) and Generalitat Valenciana Conselleria d’Educació, Investigació, Cultura i Esport
(ACIF/2020/265 and BEFPI/2021/062). / Molero Alabau, R. (2023). Estimation of Atrial Electrical Complexity during Atrial Fibrillation by Solving the Inverse Problem of Electrocardiography [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/199029 / Compendio
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