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RESUMEN Los trastornos de la repolarización ventricular son manifestaciones comunes de una amplia variedad de situaciones, entre las que se incluye la memoria cardíaca; un fenómeno no reconocido frecuentemente en la práctica diaria. La gravedad de cada una de estas causas es muy variable; sin embargo, el diagnóstico definitivo de cada una de ellas no siempre es evidente. Se presenta el caso de un paciente que acude al servicio de urgencias con dolor torácico y ondas T negativas profundas en el electrocardiograma, que simulan una isquemia miocárdica grave, y que fue definido como memoria eléctrica cardíaca.
ABSTRACT The abnormalities in ventricular repolarization are common manifestations of several conditions, among these, we can include cardiac memory, a frequently unrecognized phenomenon in medical practice. The severity of each of these causes is variable; nonetheless, a definitive diagnosis of each of them is not always evident. We present the case of a patient admitted at the emergency room with chest pain and deeply inverted T waves in the electrocardiogram, mimicking a severe myocardial ischemia, which was defined as cardiac electrical memory.
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RESUMEN Se discuten los procesos de despolarización y repolarización ventriculares, con su falta de uniformidad y su heterogeneidad, tanto en pacientes con corazón sano como en aquellos enfermos, cuestión de rangos. Se analizan las mediciones que expresan las características de la repolarización ventricular: el intervalo QT y otras mediciones incluso más fidedignas como el intervalo TPICO-TFINAL, su dispersión y otras. Se precisa la existencia del signo y del síndrome de QT largo, así como los tres procesos básicos de la arritmogenia: la heterogeneidad, la alternancia y la dispersión, con las diferencias de los potenciales de acción en las tres zonas del miocardio ventricular. Se precisan los factores de riesgo del QT largo (común con esta terapia), de las arritmias ventriculares (en especial la torsión de puntas, extremadamente rara en estos casos) y se discute la necesidad de valorar datos clínicos, eléctricos, comorbilidades, conflictos agregados y las medidas a tomar en estos pacientes.
ABSTRACT Ventricular depolarization and repolarization processes are discussed, including their differences and heterogeneity both in patients with a healthy/sick heart, a matter of ranges. Measurements expressing the characteristics of ventricular repolarization are analyzed: the QT interval and other even more reliable measurements such as the TPEAK-TEND interval, its dispersion and others. We emphasize on the existence of the long QT syndrome (and sign) and the three basic processes of arrhythmogenesis: heterogeneity, alternation and dispersion, with differences in action potentials in the three zones of the ventricular myocardium. The risk factors of long QT (common in this therapy) and ventricular arrhythmias (especially torsades de pointes, extremely rare in these cases) are highlighted. The need to assess clinical and electrical features, comorbidities, aggregate conflicts, and management of these patients is also discussed.
Subject(s)
Antineoplastic Agents , Arrhythmias, Cardiac , Long QT SyndromeABSTRACT
Objective To investigate the change in ventricular repolarization at different altitudes and time courses among healthy young males .Methods A total of 143 healthy young men living on the plains were randomly selected as subjects.Their change in relative parameters of ventricular repolarization was measured by the same person at 500 m above sea level,24 hours their ascent to the plateau at an altitude of 3700 m was,after one week′s acclimatization on the 4400 m plateau and after 50 days acclimatization on the 4400 m plateau.Results Compared with 500 m,at 3700 m above sea level in 24 hours and after one week′s acclimatization on the 4400 m plateau,the heart rate(HR),systolic blood pressure(SBP), diastolic blood pressure(DBP), heart rate-corrected-QT (QTc)interval and heart rate-corrected T-peak to T-end (TpTec) on V3 lead were significantly increased(P0.05) after 50 days acclimatization on the 4400 m plateau.Conclusion The ventricular repolarization duration of these young healthy men was significantly increased when they rapidly ascentded to high altitude .With prolonging residence at high alti-tude,the ventricular repolarization duration gradually returned to the level on the plains ,suggesting that the the ventricular repolarization duration will be restored to its level on the sea level by the adaptation and adjustment mechanism of the body .
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ObjectiveTo analyze the characteristic of the T peak-end interval (Tpe) in dilated cardiomyopathy(DCM) patients with heart failure and its significance in evaluation of global dispersion of ventricular repolarization.MethodsFifty-three inpatients were enrolled in this study,which included 28patients with DCM and heart failure (DCM group),and 25 patients with supraventricular tachycardia and without structural heart disease (control group).The Tpe and the dispersion of QT interval (QTd) from the 12-lead surface electrocardiogram(ECG) were acquired and measured,and consequently the corrected numerals of the average of Tpe (Tpe-AVEC),the maximal Tpe (Tpe-MAXC) were acquired.ResultsThe levels of Tpe-AVEC,Tpe-MAXC and QTd in DCM group were significantly higher than those in control group [ ( 106.31 ±26.34) ms vs.(82.72 ± 10.01 ) ms,(234.05 ± 69.75) ms vs.( 119.15 ± 11.55 ) ms,( 119.17 ± 67.62) ms vs.( 39.74 ± 17.04 ) ms ] ( P ＜ 0.05 or ＜ 0.01 ).ConclusionsThe global dispersion of ventricular repolarization is significantly increased in patients with DCM and heart failure.The Tpe-AVEC and Tpe-MAxc are recommended to be used for evaluating the dispersion of ventricular repolarization as the prognostic index in patients with DCM and heart failure.
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Os pacientes hipertensos apresentam morbilidade e mortalidade elevadas, em virtude da degradação do sistema cardiovascular. As alterações induzidas pelo processo hipertensivo crônico nesses doentes resulta, na maioria das vezes, no aparecimento da hipertrofia ventricular esquerda(HVE). As medidas da repolarização ventricular traduzem o estado da repolarização e as suas variações são preditivas da ocorrência de arritmias ventriculares malignas. O principal objetivo deste estudo é avaliar se a hipertensão arterial (HA) é um fator determinante da maior dispersão da repolarização ventricular e se a HVE intensifica essa alteração. Os mesmos parâmetros serão avaliados em indivíduos normais, de modo a poder realizar a comparação entre as populações. A amostra em estudo incluiu 100 pacientes hipertensos (56% do sexo feminino), com idade média de 67,64 ± 10,95, sendo divididos em dois grupos segundo a presença ou não de HVE (19% vs. 81%, respectivamente).O grupo de controle foi constituído por 141 indivíduos saudáveis (73% do sexo feminino), com idade média de 19, 12 ± 1,37. Todos os sujeitos foram submetidos à realização do eletrocardiograma de 12 derivações. Foram avaliados os intervalos QT, QTpeak, Tpeak-end e respectivas dispersões. O intervalo QTc esteve aumentado em 40% dos indivíduos em V5, 28% em DII e 25% em V1; todos os parâmetros da repolarização avaliados foram significativamente superiores nos pacientes hipertensos comparativamente ao grupo controle; 19% dos indivíduos hipertensos possuíam HVE; o intervalo Tpeak-end não foi afectado pela HVE, no entanto a sua dispersão revelou-se aumentada; o principal efeito da hipertrofia foi o aumento da dispersão QTpeak...
Patients with arterial hypertension (AH) have a high morbidity and mortality, due to the degradation of the cardiovascular system. The modifications induced by the hypertensive chronic process in these patients are in most the left ventricular hypertrophy (LVH). The measures of ventricular repolarization translate there state and his variations predict the incidence of malignant ventricular arrhythmias. The objective of this study was to investigate if AH is a determinative factor of the biggest dispersion of ventricular repolarization and if LVH intensifies this modification. The same parameters will be valued at normal individuals todo the comparison between the populations. Study group include 100 hypertensive patients (56% women), with middle age of 67,64 ± 10,95, and were divided into two groups according to the presence or not of LVH (19% vs.81%, respectively). The control group was constituted by141 healthy individuals (73% women), with middle age of 19,12 ± 1,37. All the subjects submitted the 12 derivations electrocardiogram. There were investigated the QT, QTpeak,Tpeak-end intervals and respective dispersions. The interval QTc was increased in 40% of the individuals at V5, 28% at DII and 25% at V1; all the evaluated repolarization parameters were significantly greater in the hypertensive patients than in control group; 19% of the hypertensive individuals had HVE; the Tpeak-end interval was not affected by LVH, however, his dispersion was increased; the main effect of LVH was an increase in QTpeak dispersion, in contrast to the QT dispersion, which significant differences were not obtained comparatively to the hypertensive ones without LVH. In conclusion, hypertensive patients have changes...
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Humans , Male , Female , Adult , Middle Aged , Hypertension , Hypertrophy, Left Ventricular , Ventricular RemodelingABSTRACT
La dispersión de la repolarización ventricular (DRV) está determinada esencialmente por la heterogeneidad de los potenciales de acción en diferentes regiones del miocardio. Con frecuencia el corazón responde a ciertos estados fisiopatológicos con la producción de un incremento de la DRV, fenómeno éste que puede devenir en una arritmia ventricular maligna y/o en la muerte súbita. Hace 25 años, con el objetivo de identificar a pacientes de riesgo cardíaco, se comenzó a cuantificar la DRV con diversos índices obtenidos por procesamiento computacional del electrocardiograma. Estos índices se basan en la detección de cambios en la duración o en la forma en la onda T en presencia de cardiopatías. En este trabajo se presenta una revisión de los índices de dispersión espacial y su potencialidad como herramienta de apoyo al diagnóstico de riesgo cardíaco.
The ventricular repolarization dispersion (VRD) is determined basically by the heterogeneity of the action potentials in different myocardial regions. Usually the heart responds to certain physiopathological states by producing a VRD increase, which may lead to a malignant ventricular arrhythmia and/or sudden death. For 25 years, the VRD has been quantified with several indexes obtained by computerprocessing the electrocardiogram, in order to identify cardiac- risk patients. These indexes are based on the detection of T wave changes in duration or form, in the presence of cardiopathies. A revision of the spatial dispersion indexes and their potential as supporting tool for the diagnosis of cardiac risk is presented in this work.
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La medición del intervalo QT y QT corregido es importante en el seguimiento de pacientes cardiópatas así como de aquellos que reciben medicamentos que de una u otra forma afectan dicho intervalo. Se revisan las fórmulas más conocidas para el cálculo del QT corregido y se estudia su aplicación clínica
The measurement of the interval QT and corrected QT is important in the follow-up of cardiac patients as well as from those who receive medicines which of one or another form affect this interval. The most well-known formulas for the calculation of the corrected QT are reviewed and its clinical application are studied
Subject(s)
Humans , Male , Adolescent , Adult , Female , Child , Middle Aged , Heart Diseases/etiology , Heart Diseases/pathology , Heart Diseases/therapy , Electrocardiography/methods , Heart Rate/immunology , Jervell-Lange Nielsen Syndrome/physiopathology , Romano-Ward Syndrome/physiopathology , Arrhythmias, Cardiac/pathology , Calcium Channels , Radiation , Sodium ChannelsABSTRACT
PURPOSE: The object of this study is to determine whether QT interval variability in patients with postoperative tetralogy of Fallot increases. METHODS: We enrolled 41 patients who had total correction of tetralogy of Fallot, and 31 healthy controls. They were 6-12 years old. Patients were divided into 2 groups : arrhythmia-positive patients(n=10) who had ventricular premature contractions more than 30/hour or who had couplets, and arrhythmia-negative patients(n=31). We selected the 10-minute arrhythmia-free portion of 24-hour ambulatory ECG recorded during sleep(1-3AM). We selected the 2nd beat of recordings for a template, then found the QT interval for each beat. The method was that T-wave shape best matches template T-wave under the time-stretch model. The mean heart rate and variance and mean QT interval and variance were computed and then a QT variability index(QTVI)-which represents the log ratio between QT interval variability and heart rate variability-was derived. RESULTS: Postoperative tetralogy of Fallot patients with/without ventricular arrhythmia showed significantly increased QTVI compared with the control(-0.481+/-0.310/-0.661+/-0.376 vs -1.200+/-0.380, P<0.0001). There was a trend that QTVI in patients with ventricular arrhythmia increased more than in patients without ventricular arrhythmia, but there were no statistical significances. CONCLUSION: QT interval variability increased in repaired tetralogy of Fallot patients with/without ventricular arrhythmia compared with the control. And this finding indicates that inhomogeneity of temporal ventricular repolarization exists in repaired tetralogy of Fallot patients.
Subject(s)
Humans , Arrhythmias, Cardiac , Electrocardiography , Heart Rate , Tetralogy of FallotABSTRACT
BACKGROUND: It is known that QT dispersion represents asynchronous repolarization of ventricle which is related to ventricular fibrillation. The incidence of ventricular arrhythmia is increased after acute myocardial infarction. So this study compared QT dispersion and other repolarization indexes for detection of asynchronous repolarization in acute myocardial infarction. We also investigated which portion of repolarization is the key portion of the asynchrony. METHODS: In 37 acute myocardial infarction patients and 38 angina patients dispersion of QT, JT, JTpeak and QTpeak were measured. We also measured maximum adjacent dispersion of same parameters in precordial leads. In 20 survived patients and 17 dead patients after acute myocardial infarction were also compared. We also investigated correlation of PVC's on Holter monitoring with these repolarization parameters. RESULTS: 1) All ventricular repolarization indexes(QT, QTc, JT, JTpeak, QT peak and TpeakTend dispersion) were significantly increased in acute myocardial infarction group than compared with those of angina group(p<0.05). 2) Maximal precordial dispersion(QT, QTc, JT, JTpeak and QTpeak) were also significantly increased in acute myocardial infarction group than angina group(p<0.05). 3) Dead patient group after myocardial infarction showed significantly increased QTc and TpeskTend dispersion compared with those of survived patient group(p<0.05). 4) Multivariate linear correlation showed that TpeakTend dispersion and JT dispersion was correlated with QT dispersion. CONCLUSIONS: There were asynchronous myocardial repolarization changes in acute myocardial infarction. Our study demonstrated that T wave change was major determinant of dispersion of myocardial repolarization.