Síndrome de QT largo congénito y bradicardia fetal: la importancia del diagnóstico / Congenital long QT syndrome and fetal bradycardia: the importance of the diagnosis

Antecedentes: El síndrome de QT largo es una canalopatía que afecta a la repolarización ventricular y aumenta el riesgo de sufrir arritmias ventriculares graves. Puede ser congénito o adquirido, y es una causa conocida de muerte súbita. Caso clínico: Gestante primigesta, de 28 años, sin antecedentes de interés. En ecografías prenatales se objetivó en el feto bradicardia sinusal mantenida desde la semana 28, sin repercusión hemodinámica, que persistió hasta la finalización de la gestación (semana 37+3). Al nacimiento se realizaron electrocardiogramas seriados que mostraron alteraciones en la repolarización con alargamiento del intervalo QT corregido. Se realizó estudio genético que confirmó síndrome de QT largo tipo 1 y se inició tratamiento oral con beta-bloqueantes, con buena respuesta. Conclusiones: El síndrome de QT largo suele diagnosticarse posnatalmente. Es importante conocer sus características clínicas prenatales para poder establecer un diagnóstico precoz y minimizar así el riesgo de muerte súbita de estos pacientes.

Background: Long QT syndrome is a channelopathy that affects ventricular repolarization and increases the risk of severe ventricular arrhythmias. It can be congenital or acquired, and is a known cause of sudden cardiac death. Case report: A 28-year-old primigravida with no significant medical history. Prenatal ultrasounds revealed sustained fetal sinus bradycardia from week 28, without hemodynamic repercussion, which persisted until the end of gestation (at 37+3 weeks). Serial electrocardiograms were performed after birth, showing repolarization abnormalities with prolonged corrected QT interval. A genetic study confirmed long QT syndrome type 1, and oral treatment with beta-blockers was initiated, showing a positive response. Conclusions: Long QT syndrome is often diagnosed postnatally. It is important to be aware of his prenatal clinical features in order to establish an early diagnosis and minimize the risk of sudden death in these patients.

QT interval prolongation in people treated with bedaquiline for drug-resistant tuberculosis

Background: Bedaquiline (BDQ) is indeed recommended for treating multidrug-resistant tuberculosis (MDR-TB). However, it's essential to monitor patients receiving bedaquiline therapy closely because it has been associated with prolongation of the QTc interval. This study aimed to assess the association of bedaquiline to QT interval prolongation in DR-TB patients. Methods: This was an observational longitudinal study conducted in the Department of Respiratory Medicine in Chest Disease Hospital, Rajshahi, from August 2020 to February 2023. A total of 44 MDR-TB patients were included in the study. Data analyses were done by using Statistical Package for Social Sciences (SPSS) version 25.0. Results: Out of 44 patients the majority 30(68.2%) patients belonged to age >40 years with a mean age of 49.3±15.6 years, and all patients were male. All MDR patients were detected by sputum Gene-Xpert, 44 (100%), and sputum for AFB culture was done in all patients, 44 (100%). QT level and QT changes were statistically significant for baseline and 24 weeks. Only one patient died in 2 weeks of follow-up (Table 3). Changes of QT >60 ms was found in 6 (13.6%) and ?60 ms was 38 (86.4%). Age, sex, marital status, residence, educational status, occupational status, monthly income, chief complaints, co-morbidities, and using drug-causing QT prolongation were not statistically significant (p>0.05). Conclusions: Prolonged QT interval is in DR-TB patients who receive treatment using the bedaquiline regimen. We observed that with a moderate prolongation of QTc, there were no arrhythmias recorded and 1 death occurred due to acute MI.

A Survey on QT Correction for Methadone Administration

We investigated the impact of Bazett (B) and Fridericia (F) correction formulas on the evaluation of QT prolongation in patients during methadone administration and to explore the relationship between heart rate and corrected QT interval (QTc) according to both correction formulas. This study was conducted as a single-center, retrospective observational study. Subjects were cancer patients who underwent electrocardiographic evaluation for methadone therapy at our institute from April 1, 2013, to August 31, 2023. The study assessed the incidence of QT prolongation and analyzed the correlation between heart rate and QTc derived from the B and F formulas. The mean QTc of 430.3±25.8 msec for the B formula and 409.2±20.8 msec for the F formula. The incidence of QT prolongation was significantly lower with the F formula (8.4%) compared to the B formula (27.7%), indicating a 19.3% reduction in QT prolongation cases (p<0.001). Additionally, the difference in QTc between the two formulas increased with an increase in heart rate (p<0.001). These results suggest that the F formula for QT interval correction in methadone therapy potentially expands the eligible patients for this therapy.

Study on the mechanism of astragalus glycyrrhiza decoction regulating SIRT1 / FOXO1 pathway to prevent QT interval prolongation induced by arsenic trioxide based on metabolomics / 中国临床药理学与治疗学

AIM: To explore the protective effect of astragalus glycyrrhiza decoction (AGD) on arsenic trioxide (ATO)-induced QT interval prolongation and its mechanism based on metabonomics. METHODS: The model of ATO-induced QT interval prolongation in rats was established, and ECG, blood routine, and metabonomics were detected, and the key targets were collected combined with network pharmacology. The possible candidate genes and pathways for the protective effect of AGD were screened by GO and KEGG enrichment analysis and then verified by experiments in vitro. RESULTS: AGD could significantly alleviate the ATO-induced QT interval of SD rats. GO enrichment analysis was mainly related to inflammatory response, reactive oxygen species, oxidative stress, inner cell vesicles, folds, inner cell vesicles, SMAD binding, R-SMAD binding, and signal receptor activator activity. KEGG analysis showed that it was mainly concentrated in the PI3K-Akt signal pathway, lipid and arteriosclerosis, FOXO signal pathway, TNF signal pathway, HIF-1, and other signal pathways. Through the H9c2 cell model in vitro, it was verified that AGD could reverse the expression of SIRT1 and FOXO1 proteins. CONCLUSION: AGD may improve the ATO-induced QT interval prolongation and reduce the cardiotoxicity of ATO by regulating the SIRT1 / FOXO1 signal pathway.

Efecto de los fármacos en la prolongación del QT y la aparición de muerte súbita en la COVID-19 / Effect of Drugs on QT Prolongation and Sudden Death in COVID-19

Introducción: Las evidencias científicas han demostrado que durante el período pandémico por la COVID-19 ha existido un incremento de la incidencia de muerte súbita cardiovascular, proporcional al incremento de los casos y a la letalidad por la enfermedad. Objetivos: Compilar información sobre los fármacos empleados en el tratamiento de la COVID-19 y sus posibles efectos en la prolongación del intervalo QT y la aparición de muerte súbita. Métodos: Se realizó una búsqueda de información a partir de las bases de datos PubMed, Medline y SciELO, en los idiomas español e inglés en el período de enero de 2020 a enero de 2023. Resultados: Los hallazgos más recientes sugieren que los factores relacionados con el tratamiento médico del paciente para sus enfermedades cardiovasculares previas, el empleo concomitante de drogas para otras comorbilidades, el ensayo de nuevas drogas que se investigan en la actualidad para el tratamiento de la enfermedad y el uso inadecuado de fármacos en complicaciones graves por la COVID-19, pueden ocasionar prolongación del intervalo QT y arritmias ventriculares tipo torsades de pointes, lo que puede conllevar a la aparición de muerte súbita. Conclusiones: Ha sido demostrado el efecto deletéreo de los fármacos en el tratamiento de la COVID-19 y sus posibles asociaciones a la terapéutica del paciente, en la prolongación del tiempo de repolarización ventricular cardíaca, cuya traducción eléctrica es un intervalo QT prolongado y su contribución a la génesis de arritmias malignas potencialmente fatales capaces de desencadenar un paro cardíaco y evolucionar a la muerte súbita(AU)

Scientific evidence has shown an increase in the incidence of sudden cardiovascular death during the COVID-19 pandemic period. This has been proportional to the increase in cases and mortality from the disease. Direct and indirect injury to the myocardium and vascular system allow to partially explain the statistics. Among the factors related to the medical treatment of the patient for previous cardiovascular diseases, it is the concomitant use of drugs for other comorbidities. The trial of new drugs for the treatment of this condition and the inappropriate use of drugs in serious complications from COVID-19 are currently being investigated. These can cause QT prolongation and torsades de pointes ventricular arrhythmias, which can lead to sudden death. Monitoring the QT interval is recommended, before and during treatment, in patients who come to the emergency room with a clinical condition suggestive of COVID-19. Additionally, modifiable factors favoring its prolongation should be evaluated. Decision-making in the application of therapeutic protocols in patients with COVID-19 with prolonged QTc at baseline, or with increased QTc after starting treatment, must go through the analysis of the risk/benefit ratio defined by a multi- and interdisciplinary team(AU)

Desfibrilador subcutáneo. Primeros casos en el Instituto Nacional de Cardiología, incluyendo dos pacientes pediátricos / Use of subcutaneous cardioverter-defibrillator. First cases reported from National Institute of Cardiology Ignacio Chávez-Mexico

Resumen Introducción: El desfibrilador automático implantable (DAI) transvenoso es el tratamiento de elección para la prevención de muerte súbita (MS) cardiaca por arritmias ventriculares malignas. Su uso se puede ver limitado cuando existe infección del sistema de estimulación o en población pediátrica donde representa un reto por diversas razones, incluyendo: las mínimas dimensiones del sistema venoso de los niños, la longitud de los electrodos, el tamaño del generador, así como por la complejidad anatómica en casos de cardiopatía congénita asociada. Objetivo: El presente artículo tiene por objetivo presentar la primera serie de casos de pacientes mexicanos a los cuales se les implantó un DAI subcutáneo (DAI-SC) como terapia para la prevención de MS. Métodos: Se presentan los cuatro primeros casos que fueron implantados en el Instituto Nacional de Cardiología Ignacio Chávez con un DAI-SC (Emblem, Boston Scientific, EE.UU.), tres de ellos eran pacientes pediátricos, incluyendo el primer implante de este tipo de dispositivo en un paciente pediátrico en América Latina. Las técnicas de tres y dos incisiones fueron empleadas bajo anestesia general. Resultados: Se realizó el implante exitoso con técnica de tres incisiones en los dos primeros casos y con técnica de dos incisiones en los dos últimos casos. Se corroboró el adecuado funcionamiento del dispositivo en sala, con la verificación de terapia apropiada (65 J) de la fibrilación ventricular inducida mediante estimulación a 50 Hz. No hubo complicaciones inmediatas. Un paciente presentó descargas apropiadas a los dos meses del implante. En el seguimiento, un niño desarrolló erosión de la piel a nivel de la curva del electrodo en el esternón, sin datos de infección. En quirófano se resecó la piel dañada, se retiró el barril y la seda de fijación, se realizó lavado quirúrgico y se volvió a cerrar la piel, logrando así evitar el retiro del sistema. Conclusiones: El DAI-SC es una terapia alternativa al DAI endovenoso y puede ser considerado de primera elección en aquellos casos que no requieran de estimulación ventricular, incluyendo pacientes pediátricos. Pueden ocurrir complicaciones cutáneas, pero no representan una amenaza como las complicaciones venosas de los DAI convencionales.

Abstract Introduction: The transvenous implantable cardioverter defibrillator (ICD) is the treatment of choice for the prevention of sudden cardiac death (SCD). Its use could be restricted when device-related infections occurs or in the pediatric population. In the later, an ICD represents a challenge, due to the minimal dimensions of the venous system in children, the length of the electrodes, the size of the generator, as well as the anatomical complexity in cases with associated congenital heart disease. Objective: This article presents the first Mexican patients with a subcutaneous ICD (SC-ICD) implant as a therapy for the prevention of SCD. Methods: The first four cases were implanted at the Ignacio Chávez National Institute of Cardiology with a SC-ICD (Emblem, Boston Scientific, USA), three of them were pediatric patients, including the first implant of this type of device in a pediatric patient in Latin America. The 3-incision and 2-incision techniques were used under general anesthesia. Results: A successful implantation was obtained with the 3-incision technique in the first 2 cases and the last 2 with the 2-incision technique. Proper functioning of the device was corroborated in the operating room with proof of appropriate therapy (65 J) for ventricular fibrillation induced with 50 Hz stimulation. No immediate complications were observed. One patient had appropriate shocks two months after the implant. During follow-up, one child developed skin erosion at the level of the curve of the electrode on the sternum, with no signs of infection. In the operating room, the damaged skin was resected, the barrel and the fixation silk were removed, surgical lavage was performed, and the skin was closed again, thus avoiding removal of the system. Conclusions: The SC-ICD is an alternative therapy to the transvenous ICD. It can be considered first choice in subjects who do not require ventricular pacing, including pediatric patients. Skin complications can occur but do not pose a threat as venous complications of conventional ICDs.

Taquicardia ventricular polimórfica tipo torsadess de pointes secundaria a estimulación por marcapasos / Polymorphic ventricular taquicardia "torsades de pointes" associated to abnormal pacemaker stimulation

La taquicardia ventricular polimórfica se origina en los ventrículos, cuyos complejos QRS son de morfología, amplitud y dirección variable, con frecuencias que oscilan entre 200 y 250 lpm, pudiendo ser autolimitadas o degenerar en una fibrilación ventricular. La TdP es un tipo de taquicardia ventricular polimórfica caracterizada por complejos con un eje eléctrico que gira alrededor de la línea isoeléctrica y que está asociada a QT largo. Se presenta el caso de una paciente portadora de marcapaso que presenta episodios de taquicardia ventricular polimórfica, con una morfología típica de TdP, sin documentación de QT prolongado previo ni actual, generada por la estimulación ventricular sobre onda T, de forma accidental por desplazamiento del electrodo auricular a Ventrículo Derecho (VD).

Polymorphic ventricular tachycardia is a tachycardia originating in the ventricles, where the QRS complexes have variable morphology, amplitude, and direction, with frequencies ranging between 200 and 250 bpm; it may be self-limited or degenerate into ventricular fibrillation. Torsades de Pointes (TdP) is a type of polymorphic ventricular tachycardia characterized by complexes with an electrical axis that rotates around the isoelectric line and that is associated with long QT interval. We present the case of a patient with a pacemaker who presents episodes of polymorphic ventricular tachycardia, with a typical morphology of TdP, without documentation of previous or current prolonged QT, generated by ventricular stimulation on the T wave, accidentally due to displacement of the atrial electrode to the Right Ventricle (RV).

Assessment of QT Interval Abnormalities on Electrocardiogram in Children With Breath-Holding Spells

Objective: To assess QT interval abnormalities among children with breath-holding spells. Methods: This case control study included 204 children (104 cases of breath-holding spells and 100 healthy children) younger than 3 years. Breath-holding spells were evaluated for age of onset, type (pallid/cyanotic), triggering factors, frequency and presence of family history. Twelve- lead surface electrocardiogram (ECG) was analyzed for QT interval (QT), corrected QT interval (QTc), QT dispersion (QTD) and QTc dispersion (QTcD) in milliseconds. Results: The mean (SD) QT, QTc, QTD and QTcD interval in milliseconds were 320 (0.05), 420 (0.07), 61.15 (16.20), 102.3 (17.24), respectively for breath-holding spells as compared to control group [300 (0.02), 370 (0.03), 38.6(14.28), 78.6 (14.28), respectively] (P<0.001). Similarly, pallid breathholding spells had prolonged mean (SD) QT, QTc, QTD and QTcD interval in milliseconds [380 (0.04), 520 (0.08), 78.88 (10.78), 123.33 (10.28), respectively] as compared to cyanotic spells [310 (0.04), 400 (0.04), 57.44 (14.64), 97.90 (15.03), respectively] (P<0.001). The mean QTc interval was 590 (0.03) and 400 (0.04) milliseconds in prolonged and non-prolonged QTc group, respectively (P<0.001). Conclusion: Abnormal QT, QTc, QTD and QTcD were observed among children with breath-holding spells. ECG should be strongly considered, especially in pallid, frequent spells occurring at younger age and having positive family history, to identify long QT syndrome.

A Rare Case Report of “Torsades De Pointes” Induced by Fluconazole-Levetiracetam Combined Therapy

Drugs used to treat cardiovascular disease as well as those used in the treatment of multiple other conditions can occasionally produce exaggerated prolongation of the QT interval on the surface electrocardiogram and the morphologically distinctive polymorphic ventricular tachycardia that results is known as «torsade de pointe». «Torsade de pointe» (TDP) is a characteristic polymorphic ventricular arrhythmia associated with delayed ventricular repolarization as evidenced on the surface electrocardiogram by QT interval prolongation. It typically occurs in self-limiting bursts, causing dizziness and syncope, but may occasionally progress to ventricular fibrillation and sudden death. This rare case report showed the potential higher risk of the occurrences of «Tdp» when levetiracetam (KEPPRA) was used in combination therapy with fluconazole, which is already a known medication with the risk of causing polymorphic ventricular arrhythmia.

Taquicardia ventricular polimorfa en un paciente con fibrilación auricular de respuesta ventricular rápida. Reporte de Caso

Las taquicardiomiopatías por su fisiopatología de pérdida del acoplamiento miocárdico, proporcionan el sustrato adecuado para la disfunción ventricular que dan paso a arritmias ventriculares letales. Se reporta el caso de una paciente femenina de 75 años, sin antecedentes personales patológicos conocidos, que acude con historia de disnea de medianos esfuerzos que rápidamente progresa a disnea de pequeños esfuerzos asociado a palpitaciones. Posteriormente desarrolla taquicardia ventricular polimorfa no sostenida durante su estancia hospitalaria por lo que fue necesario realizar en dos ocasiones maniobras de reanimación con cardioversión eléctrica y el restablecimiento del ritmo sinusal con fármacos para mejorar la función del ventrículo izquierdo. (provisto por Infomedic International)

  Tachycardiomyopathies due to their pathophysiology of loss of myocardial coupling, provide the adequate substrate for ventricular dysfunction that leads to lethal ventricular arrhythmias. The following is the case of a 75-year-old female patient, with no known history, who presented with symptoms of advanced heart failure and atrial fibrillation, who later developed non-sustained polimorphic ventricular tachycardia during her hospital stay for which it was necessary to perform resuscitation maneuvers with electrical cardioversion on two separate occasions and the restoration of sinus rhythm with drugs to improve left ventricular function. (provided by Infomedic International)

Clinical Study of Cardiac Autonomic Dysfunction and QT Dispersion in Newly Diagnosed HIV Positive Individuals and its Correlation with CD4 Count

Background: HIV is a global pandemic with an estimated 38 million People Living with HIV (PLHIV) worldwide. Autonomic nervous dysfunction is seen more frequently in PLHIV and Cardiac autonomic dysfunction affects severely the quality of life in them. Early detection of autonomic neuropathy helps in the rehabilitation of PLHIV. Objectives: To evaluate the presence and extent of cardiac autonomic dysfunction and QT dispersion in newly diagnosed PLHIV, and To correlate autonomic with CD4 count. Method: Age and sex-matched Case-control study was conducted in the hospitals attached to Bangalore Medical College and Research Institute (BMCRI). 30 patients (15 HIV positive with AIDS and 15 HIV positive without AIDS) and 30 healthy controls who gave consent for the study and satisfied the inclusion and exclusion criteria were enrolled in the study. Cardiac autonomic function was assessed by Ewing’s battery of autonomic function tests and QT dispersion was measured. Statistical analysis was performed using SPSS software for Windows and a p-value <0.05 was considered significant. Results: Abnormal cardiac autonomic function was observed in 20% of patients with AIDS and 6.6% of patients without AIDS. There was statistically significant differences observed between PLHIV and controls for systolic blood pressure fall on standing (p=0.02), heart rate response to deep breathing (p=0.017), to standing(p=0.004), and to Valsalva maneuver(p=0.035). 33.3% of PLHIV had abnormal QT dispersion. Conclusions: Increase in the severity of cardiac dysautonomia was seen as the CD4 counts reduced to <200 cells/microL.QT dispersion is an important predictor of cardiac autonomic dysfunction. Autonomic function tests should be performed for early detection of cardiac dysautonomia which is an important contributor to mortality and morbidity in PLHIV.

Clinical features and follow-up of congenital long QT syndrome in children with syncope as the first presentation / 中国小儿急救医学

Objective:To investigate the pathogenic genes, clinical features and treatment as well as follow-up of children with congenital long QT syndrome (LQTS).Methods:The clinical data, genetic test results and follow-up data of 16 congenital LQTS children with syncope as the first manifestation admitted to the Department of Cardiology, Beijing Children′s Hospital Affiliated to Capital Medical University from August 2016 to March 2023 were collected and retrospectively analyzed.Results:Among the 16 LQTS patients, the age of first syncope onset was 1.3-13.3 (7.37±3.41) years, and the interval between first syncope onset and clinical diagnosis was 0-48 (14.8±16.2) months.A total of 13 (81.3%) patients had triggers of syncope, of which nine were exercise-induced and four were emotional induced.Genetic testing was performed in 13 patients with LQTS, of which 12 (92.3%) were found to have pathogenic or suspected pathogenic mutations from KCNQ1, KCNH2, and SCN5A gene.The corrected QT interval of 16 patients was (550.0±50.2) ms, all cases≥460 ms.Schwartz scored 6.0 (5.0, 6.0) points, all cases≥4 points.All patients were initially treated with metoprolol or propranolol, of which 14 patients were followed up to date, three patients had recurrent syncope, and five patients stopped taking the medicines by themselves.One patient with high-dose metoprolol (LQT2) was treated with mexiletine after recurrent episodes.One patient who was intolerant to high-dose propranolol underwent left cardiac sympathectomy and was followed up after surgery without syncope episodes.None of the patients underwent implantable cardioverter defibrillator implantation. Conclusion:Children with LQTS and syncope symptoms have high positive rate of genetic tests.The genetic results could assist typing of patients with LQTS and guide treatment.Routine electrocardiogram screening in children with syncope may diagnose LQTS earlier and reduce misdiagnosis and missed diagnosis.β-blockers are the cornerstone of treatment for patients with LQTS.Strengthening follow-up management and improving patients′ treatment compliance is conducive to further improving the treatment response rate of patients.

Syndrome de QT long découvert en postpartum: à propos d'un cas à Fianarantsoa, Madagascar / Long QT syndrome discovered in postpartum: about a case in Fianarantsoa, Madagascar

Le syndrome de QT long congénital est une canalopathie arythmogène rare mais grave pouvant être responsable d'une mort subite prématurée chez l'enfant et les sujets jeunes. La période du postpartum est particulièrement à risque de survenue d'évènement cardiaque chez la femme. Nous rapportons le cas d'une femme de 29 ans porteuse d'un syndrome de QT long congénitale probable déclenché avec trouble du rythme cardiaque déclenché par le postpartum dont le risque de mort subite à court terme a été imminent en absence de traitement

Severe primary hypothyroidism presenting as polymorphic ventricular tachycardia / Hipotiroidismo primario grave que se presenta como taquicardia ventricular polimórfica

Abstract Introduction: Hypothyroidism may have various cardiovascular manifestations due to morphological, functional and electrical alterations in the heart. The usual electrocardiographic findings being sinus bradycardia, low voltage complexes, and slowed intraventricular conduction. Hypothyroidism manifesting as polymorphic ventricular tachycardia has only been reported in a few case reports. Clinical case. A 60-year-old lady presented to us in the emergency department in an unresponsive and unconscious state and electrocardiogram showed a polymorphic ventricular tachycardia. After initial resuscitation with direct current cardioversion and supportive care, she found to have severe hypothyroidism and responded well to thyroid replacement therapy. Conclusion. Polymorphic ventricular tachycardia is a life threatening emergency that can have various etiologies. Polymorphic ventricular tachycardia secondary to primary hypothyroidism is a rare presentation but it is treatable and reversible with thyroid replacement therapy. In patients presenting with QT interval prolongation and ventricular tachycardia, hypothyroidism should be one of the differential diagnosis.

Resumen Introducción: El hipotiroidismo puede presentar diferentes manifestaciones cardiovasculares dadas por alteraciones morfológicas, funcionales y eléctricas en el corazón, siendo los hallazgos electrocardiográficos usuales son la bradicardia sinusal, los complejos de bajo voltaje y la conducción intraventricular lenta. El hipotiroidismo manifestado como taquicardia ventricular polimórfica solo se ha descrito en unos pocos reportes de caso. Caso clínico: Se trata de una mujer de 60 años que acudió que acurdió al servicio de urgencias en un estado inconsciente y sin respuesta a estímulos, y el electrocardiograma reveló taquicardia ventricular polimórfica. Luego de la reanimación inicial con cardioversión con corriente directa y tratamiento sintomático se le encontró un hipotiroidismo grave, el cual se trató con terapia de reemplazo con hormona tiroidea. y se obtuvo una buena respuesta Conclusión. La taquicardia ventricular polimórfica es una emergencia vital que puede tener varias etiologías. La taquicardia ventricular polimórfica secundaria a un hipotiroidismo primario es una presentación poco común, pero es tratable y reversible con la terapia de reemplazo con hormona tiroidea. En los pacientes que presentan una prolongación del intervalo QT y taquicardia ventricular, es pertinente incluir el hipotiroidismo en el diagnóstico diferencial.

Determinação do risco potencial de interações medicamentosas prolongadoras do intervalo QT em idosos internados em unidade de terapia intensiva

Introdução: Pacientes hospitalizados em unidade de terapia intensiva, em especial idosos, são particularmente expostos a interações medicamentosas prolongadoras do intervalo QT. Objetivo: Determinar a incidência de interações medicamentosas prolongadoras do intervalo QT potenciais (IMQT) e seus preditores clínicos e terapêuticos em idosos hospitalizados em unidade de terapia intensiva. Metodologia: Coorte retrospectiva conduzida em unidade de terapia intensiva adulto. Foram incluídos prontuários de pacientes com idade igual ou superior a 60 anos com tempo de internação mínimo de 24 h e que utilizaram dois ou mais medicamentos. O Credi-bleMeds foi utilizado para classificação dos medicamentos com risco de prolongar o intervalo QT; em seguida, o Micromedex foi acessado para identificar e classificar as interações medicamentosas. Preditores clínicos e terapêuticos das interações foram examinados a partir de um modelo de regressão logística múltiplo. Resultados: A incidência de IMQT potenciais foi de 43,9 %. Os medicamentos mais frequentemente combinados nas IMQT potenciais foram ondansetrona (25 %), quetiapina (22,5 %), amiodarona (18,6 %) e haloperidol (17,5 %). As IMQT potenciais mais frequentes foram haloperidol + ondansetrona (25,4 %) seguidas pela dupla ondansetrona + quetiapina (13,1 %). Os preditores de IMQT potenciais foram uso de polifar-mácia (p=0,002), antipsicóticos (p<0,001), antidepressivos (p< 0,001) e antiarrítmicos (p=0,002). Conclusão: A gestão das IMQT requer abordagem pautada em fatores de risco individuais e também, obrigatoriamente, em condutas genéricas relativas a exames bioquímicos, instalação de monitores cardíacos, eletrocardiogramas periódicos e uso de sistemas de alerta para IMQT.

SUMMARY Introduction: Patients hospitalized in the intensive care unit, especially the elderly, are particularly exposed to drug interactions that prolong the QT interval. AIM: To determine the incidence of potential QT-prolonging drug interactions (IMQT) and their clinical and therapeutic predictors in elderly patients hospitalized in an intensive care unit. Methodology: Retrospective cohort conducted in an adult intensive care unit. Medical records of patients aged 60 years or older with a minimum hospital stay of 24 hours and who used two or more medications were included. CredibleMeds was used to classify drugs at risk of prolonging the QT interval; then, Micromedex was accessed to identify and classify drug interactions. Clinical and therapeutic predictors of interactions were examined using a multiple logistic regression model. Results: The incidence of potential IMQT was 43.9 %. The drugs most frequently combined in potential MTMI were ondansetron (25 %), quetiapine (22.5 %), amiodarone (18.6 %) and haloperidol (17.5 %). The most frequent potential MTMI were haloperidol + ondansetron (25.4 %) followed by the dual ondansetron + quetiapine (13.1 %). Potential IMQT predictors were use of polypharmacy (p=0.002), antipsychotics (p<0.001), antidepressants (p<0.001) and antiarrhythmics (p=0.002). Conclusion: The management of IMQT requires an approach based on individual risk factors and also, necessarily, on generic conducts related to biochemical tests, installation of cardiac monitors, periodic electrocardiograms and use of warning systems for IMQT.

Introducción: Los pacientes hospitalizados en la unidad de cuidados intensivos, especialmente los ancianos, están particularmente expuestos a interacciones medicamentosas que prolongan el intervalo QT. Objetivo: Determinar la incidencia de posibles interacciones medicamentosas prolongadoras del intervalo QT (IMQT) y sus predictores clínicos y terapéuticos en pacientes ancianos hospitalizados en una unidad de cuidados intensivos. Metodología: Cohorte retrospectiva realizada en una unidad de cuidados intensivos para adultos. Se incluyeron historias clínicas de pacientes de 60 años o más con una estancia hospitalaria mínima de 24 horas y que utilizaban dos o más medicamentos. Se utilizó CredibleMeds para clasificar los fármacos con riesgo de prolongar el intervalo QT; luego, se accedió a Micromedex para identificar y clasificar las interacciones medicamentosas. Los predictores clínicos y terapéuticos de interacciones se examinaron mediante un modelo de regresión logística múltiple. Resultados: La incidencia de IMQT potencial fue del 43,9 %. Los fármacos combinados con mayor frecuencia en posibles MTMI fueron ondansetrón (25 %), quetiapina (22,5 %), amiodarona (18,6 %) y haloperidol (17,5 %). Los MTMI potenciales más frecuentes fueron haloperidol + ondansetrón (25,4 %) seguido de ondansetrón dual + quetiapina (13,1 %). Los posibles predictores del IMQT fueron el uso de polifarmacia (p=0,002), antipsicóticos (p<0,001), antidepresivos (p<0,001) y antiarrítmicos (p=0,002). Conclusión: El manejo del IMQT requiere un abordaje basado en factores de riesgo individuales y también, obligatoriamente, en conductas genéricas relacionadas con pruebas bioquímicas, instalación de monitores cardíacos, electrocardiogramas periódicos y uso de sistemas de alerta para IMQT.

Prevalencia de medicamentos que prolongan el intervalo QT en salas de cardiología de un hospital de alta complejidad / Drug induced prolongation of Q-T interval in cardiology wards

Resumen: Antecedentes: La prevalencia del síndrome del QT largo (SQTL) producido por medicamentos es una de las reacciones adversas que en el último tiempo ha aumentado en prevalencia y mortalidad. No solamente ocurre con el uso de medicamentos para el tratamiento de cardiopatías, sino también en medicamentos con otra acción terapéutica. Objetivo: Evaluar la prevalencia del síndrome del SQTL inducido por medicamentos en salas de cardiología de un hospital de alta complejidad. Métodos: Estudio prospectivo, de tipo descriptivo y de corte transversal en 36 pacientes cardiópatas, que consistió en evaluar la frecuencia del uso de medicamentos que son capaces de producir un SQTL y la prevalencia de este efecto adverso. Los datos clínicos se recolectaron de la ficha clínica y de entrevistas con los pacientes. Se efectuó un seguimiento para detectar la aparición de prolongación del intervalo QT. Los resultados obtenidos fueron presentados por medio de estadística descriptiva (programa estadístico Statgraphics Centurion, versión XVI). No hubo estadística inferencial dada la ausencia de un grupo control. Resultados: 41,7%, de los 36 pacientes presentaron SQTL que en 86,7% de ellos fue asociado a un medicamento. Los medicamentos más frecuentemente asociados a este efecto adverso fueron Amiodarona (38,5%) y Ondansetrón (23,1%), y el factor de riesgo mayormente involucrado fue el sexo femenino (61,5%). Conclusión: Existió una alta prevalencia del uso de medicamentos que producen un SQTL, destacándose que existen medicamentos utilizados para otras patologías que también pueden producirlo.

Abstract: Background: The prevalence of the Long QT interval syndrome (LQTS) associated to drugs has increased en the last decades along with an increased mortality due to this condition. It occurs not only with drugs used to treat cardiac disease but also to other drugs. Aim: To evaluate the prevalence of drug induced LQTS in cardiology wards of a high complexity hospital. Method: This is a prospective, descriptive and cross sectional study in 36 patients with heart disease. The use of drugs known to affect the QT interval along with the frequency of LGTS were evaluated. Clincal data was obtained from clinical records and personal interviews. Patients were followed for the appearance of LQTS. Descriptive were used to present the results. No inferential statistics were used as no control group was involved (Statgraphics Centurion, version XVI). Results: 41.7% of the 36 patients developed LQTS and the association with drugs was present in 86.7% of them. The drugs most commonly identified were amiodarone (38.5%) and ondansetron (23.1%) of patients. Female geneder was the most common associated condition (61.5%). Conclusion: There was a frequent use of drugs known to produce LQTS, but other drugs may also be associated int this group of patients with heart disease admitted to intensive or intermediate care facilities.

The QT Interval: What the Pulmonologist Needs to Know

The QT interval is an electrocardiographical measurement that denotes the time interval between the commencement and completion of the cardiac ventricular contraction process. Alterations in its value indicate abnormal cardiac rhythm and herald the risk of torsades de pointes; a fatal ventricular arrhythmia. Causes leading to a prolonged QT interval encompass a heterogeneous gamut including genetic conditions, electrolyte imbalances, hormonal imbalances, and drugs. A wide range of drugs can lead to a prolonged QT interval and these include certain crucial drugs which are routinely prescribed by a pulmonologist for infectious as well as non-infectious pulmonary indications. This becomes particularly relevant in this decade which has witnessed an excrescence in drug-resistant tuberculosis cases. Certain vital drugs employed in its management prolong QT interval significantly. In these situations, the clinician faces the predicament of cautiously prescribing these drugs to eradicate the disease microbiologically whilst balancing the risk of sudden cardiac death due to torsades de pointes. We summarise the basics of QT interval which every pulmonologist presently needs to know.

Diagnostic Lacunae and Implications of an Automated Implantable Cardioverter Defibrillator Implantation in a Child with Type 3 Long QT (LQT3) Syndrome

A diagnosis of congenital long QT interval syndrome based on history and electrocardiogram was made in a child in the absence of readily available genetic testing. A genotype 3 (LQT3) was suspected after exclusion of other variants as the child was non?responsive to beta?blocker and sodium channel blocker medication. As the child continues to show episodic bradycardia, polymorphic ventricular ectopy, and T?wave alternans, a single?chamber automated implantable cardioverter?defibrillator implantation was done successfully. This report highlights how the diagnosis of LQT3 was arrived at as well as the anesthetic challenges in the management of patients with LQTS.