Performance comparison of 6 in-hospital patient monitoring systems in the detection and alarm of ventricular cardiac arrhythmias.

Background: Patient monitoring devices are critical for alerting of potential cardiac arrhythmias during hospitalization; however, there are concerns of alarm fatigue due to high false alarm rates.

Objective: The purpose of this study was to evaluate the sensitivity and false alarm rate of hospital-based continuous electrocardiographic (ECG) monitoring technologies.

Methods: Six commonly used multiparameter bedside monitoring systems available in the United States were evaluated: B125M (GE HealthCare), ePM10 and iPM12 (Mindray), Efficia and IntelliVue (Philips), and Life Scope (Nihon Kohden).

Optogenetic dephosphorylation of phosphatidylinositol 4,5 bisphosphate in Xenopus laevis oocytes.

Here, we present a protocol for optogenetic dephosphorylation of the phosphoinositide PI(4,5)P at the plasma membrane of Xenopus laevis oocytes. We first describe the co-injection of oocytes with cRNAs encoding (1) a light-activated PI(4,5)P 5-phosphatase fusion protein, (2) its dimerization partner fused to the plasma membrane, and (3) the potassium channel reporter for PI(4,5)P dephosphorylation. We then detail blue light illumination to induce PI(4,5)P dephosphorylation, combined with simultaneous two-electrode voltage clamp electrophysiological recording to assess potassium channel current responses.

Effects of β-blockers on ventricular repolarization documented by 24-hour electrocardiography in long QT syndrome type 2.

Background: Long QT syndrome (LQTS) is an inherited arrhythmia disorder characterized by ventricular repolarization abnormalities and a risk of sudden cardiac death. The electrophysiological components generating the high risk of arrhythmias in LQTS are prolonged repolarization, increased dispersion of repolarization, and early afterdepolarizations, which are clinically estimated as QT interval, T-wave peak to T-wave end (TPE) interval, and T2/T1-wave amplitude ratio, respectively. In experimental LQTS type 2 (LQT2) models, β-blockers decrease dispersion of repolarization and prevent early afterdepolarizations.

Peak CK-MB has a strong association with chronic scar size and wall motion abnormalities after revascularized non-transmural myocardial infarction - a prospective CMR study.

Background: Large myocardial infarction (MI) is associated with adverse left ventricular (LV) remodeling (LVR). We studied the nature of LVR, with specific attention to non-transmural MIs, and the association of peak CK-MB with recovery and chronic phase scar size and LVR.

Methods: Altogether 41 patients underwent prospectively repeated cardiovascular magnetic resonance at a median of 22 (interquartile range 9-29) days and 10 (8-16) months after the first revascularized MI.

Vasomotor hot flashes and cardiac repolarization: a randomized placebo-controlled trial of postmenopausal hormone therapy.

Objective: The aim of the study was to compare the effects of different hormone therapies on cardiac repolarization in recently postmenopausal women with and without hot flashes.

Methods: We recruited 150 healthy women: 72 with and 78 without hot flashes. They were randomized and treated for 6 months with transdermal estradiol (1 mg/day), oral estradiol (OE) alone (2 mg/day) or combined with medroxyprogesterone acetate (MPA; 5 mg/day), or placebo.

Slowed depolarization and irregular repolarization in catecholaminergic polymorphic ventricular tachycardia: a study from cellular Ca2+ transients and action potentials to clinical monophasic action potentials and electrocardiography.

Aims: Spontaneous Ca release leads to afterdepolarizations and triggered arrhythmia in catecholaminergic polymorphic ventricular tachycardia (CPVT). Irregular Ca release is hypothesized to manifest as slowed depolarization and irregular repolarization. Our goal was to study depolarization and repolarization abnormalities in CPVT, as they remain largely uninvestigated.

Cardiac repolarization in recently postmenopausal women with or without hot flushes.

Objective: Menopausal hot flushes are associated with elevated activity of the sympathetic nervous system and may be related to increased risk for cardiovascular events. Sympathetic activation may trigger severe arrhythmias by modulating cardiac repolarization. The aim of this study was to evaluate the impact of hot flushes on cardiac repolarization in postmenopausal women with and without hot flushes.

Sensitivity and specificity of automated detection of early repolarization in standard 12-lead electrocardiography.

Background: Early repolarization (ER) is defined as an elevation of the QRS-ST junction in at least two inferior or lateral leads of the standard 12-lead electrocardiogram (ECG). Our purpose was to create an algorithm for the automated detection and classification of ER.

Methods: A total of 6,047 electrocardiograms were manually graded for ER by two experienced readers.

Assessment of myocardial infarct size with body surface potential mapping: validation against contrast-enhanced cardiac magnetic resonance imaging.

Background: Assessment of myocardial infarct (MI) size is important for therapeutic and prognostic reasons. We used body surface potential mapping (BSPM) to evaluate whether single-lead electrocardiographic variables can assess MI size.

Methods: We performed BSPM with 120 leads covering the front and back chest (plus limb leads) on 57 patients at different phases of MI: acutely, during healing, and in the chronic phase.

U wave features in body surface potential mapping in post-myocardial infarction patients.

Background: The data on U wave features in post-myocardial infarction (MI) remain sparse. We employed 120-lead body surface potential mapping (BSPM) to explore the U wave in patients with remote MI.

Methods: Sixty post-MI patients and 46 healthy controls were examined.

Predictive value of electrocardiographic T-wave morphology parameters and T-wave peak to T-wave end interval for sudden cardiac death in the general population.

Background: Previous population studies have found an association between electrocardiographic T-wave morphology parameters and cardiovascular mortality, but their relationship to sudden cardiac death (SCD) is not clear. To our knowledge, there are no follow-up studies assessing the association between electrocardiographic T-wave peak to T-wave end interval (TPE) and SCD. We assessed the predictive value of electrocardiographic T-wave morphology parameters and TPE for SCD in an adult general population sample.

Predicting recovery of myocardial function by electrocardiography after acute infarction.

Background: In acute ischemic left ventricular (LV) dysfunction, distinguishing viable myocardium is clinically important.

Methods: Body surface potential mapping (Electrocardiography [ECG] with 123 leads), was recorded in 62 patients with acute coronary syndrome (ACS). ECG variables were computed from de- and repolarization phases.

T-wave morphology after epinephrine bolus may reveal silent long QT syndrome mutation carriers.

Background: Long QT syndrome (LQTS) gene mutation carriers with indeterminate electrocardiogram frequently escape clinical diagnosis. We assessed the use of epinephrine bolus injection in revealing T-wave abnormalities.

Methods: We recruited 30 genotyped asymptomatic LQTS gene carriers with nondiagnostic QT interval and 15 controls.

Vasomotor hot flashes and heart rate variability: a placebo-controlled trial of postmenopausal hormone therapy.

Objective: The aim of the study was to compare the responses of heart rate variability (HRV) with hormone therapy in recently postmenopausal women with and without vasomotor hot flashes.

Methods: Seventy-two women with and 78 women without hot flashes were randomized to receive transdermal estradiol gel (1 g/day), oral estradiol alone (2 mg/day), oral estradiol combined with medroxyprogesterone acetate (MPA; 5 mg/day), or placebo for 6 months. Time- and frequency-domain measures of HRV were assessed using 24-hour electrocardiographic recordings at baseline and after hormone therapy.

The early repolarization pattern in the general population: clinical correlates and heritability.

Objectives: This study sought to describe the clinical correlates and heritability of the early repolarization pattern (ERP) in 2 large, population-based cohorts.

Background: There is growing recognition that ERP is associated with adverse outcomes.

Methods: Participants of the Framingham Heart Study (FHS) (N = 3,995) and the Health 2000 Survey (H2K) (N = 5,489) were included.

Epinephrine bolus test in detecting long QT syndrome mutation carriers with indeterminable electrocardiographic phenotype.

Background: In long QT syndrome (LQTS), prolonged and heterogeneous ventricular repolarization predisposes to serious arrhythmias. We examined how QT intervals are modified by epinephrine bolus in mutation carriers of three major LQTS subtypes with indefinite QT interval.

Methods: Genotyped, asymptomatic subjects with LQTS type 1 (LQT1; n = 10; four different KCNQ1 mutations), type 2 (LQT2; n = 10; three different HERG mutations), and type 3 (LQT3; n = 10; four different SCN5A mutations), and healthy volunteers (n = 15) were examined.

Comparison of QT peak and QT end interval responses to autonomic adaptation in asymptomatic LQT1 mutation carriers.

Background:   LQT1 subtype of long QT syndrome is characterized by defective I(Ks) , which is intrinsically stronger in the epicardium than in the midmyocardial region. Electrocardiographic QT peak and QT end intervals may reflect complete repolarization of epicardium and midmyocardial region of the ventricular wall, respectively. Repolarization abnormalities in LQT1 carriers may therefore be more easily detected in the QT peak intervals.

Dynamic QT/RR relationship in post-myocardial infarction patients with and without cardiac arrest.

Objectives: Changes in QT interval dynamicity may be associated with susceptibility to ventricular fibrillation (VF) after myocardial infarction (MI). We tested the hypothesis that dynamic QT/RR relationship might differ between post-MI patients with and without a history of VF. We also evaluated the influence of negative T-waves on the assessment of QT/RR relationship.

Abnormal repolarization dynamics revealed in exercise test in long QT syndrome mutation carriers with normal resting QT interval.

Aims: The identification of affected family members with long QT syndrome (LQTS) is often difficult due to their normal-or only marginally lengthened-QT interval duration. We examined whether physical exercise test could increase the ability to detect the mutation carrier status in phenotypically normal LQTS family members.

Methods And Results: Sixty-six subjects were included: 15 were carriers of KCNQ1 (LQT1); 15 of KCNH(2) (LQT2); and 9 of SCN5A (LQT3) gene mutations with no, or borderline, QT lengthening; and 27 were healthy controls.

Fragmented QRS in prediction of cardiac deaths and heart failure hospitalizations after myocardial infarction.

Background: Increased QRS fragmentation in visual inspection of 12-lead ECG has shown association with cardiac events in postmyocardial infarction (MI) patients. We investigated user-independent computerized intra-QRS fragmentation analysis in prediction of cardiac deaths and heart failure (HF) hospitalizations after MI.

Methods: Patients (n = 158) with recent MI and reduced left ventricular ejection fraction (LVEF) were studied.

Relationship of common candidate gene variants to electrocardiographic T-wave peak to T-wave end interval and T-wave morphology parameters.

Background: Single-nucleotide polymorphisms (SNPs) in genes encoding cardiac ion channels and nitric oxide synthase-1 adaptor protein (NOS1AP) are associated with electrocardiographic (ECG) QT-interval duration, but the association of these SNPs with new, prognostically important ECG measures of ventricular repolarization is unknown.

Objective: The purpose of this study was to examine the relationship of SNPs to ECG T-wave peak to T-wave end (TPE) interval and T-wave morphology parameters.

Methods: We studied 5,890 adults attending the Health 2000 Study, a Finnish epidemiologic survey.

Association between vasomotor hot flashes and heart rate variability in recently postmenopausal women.

Objective: The aim of this study was to investigate whether cardiovascular autonomic reactivity and risk profile are associated with the frequency and severity of hot flashes in recently postmenopausal women.

Methods: A total of 150 postmenopausal women with varying degrees of severity of hot flashes (none, mild, moderate, or severe) underwent 24-hour electrocardiographic recording. The function of the autonomic nervous system was assessed via heart rate variability in time and frequency domains.

Predictive value of electrocardiographic QT interval and T-wave morphology parameters for all-cause and cardiovascular mortality in a general population sample.

Background: The predictive value of ECG QT interval for mortality in the general population has been weak. Only a few population studies on the predictive value of ECG T-wave morphology parameters for mortality have been reported.

Objective: The purpose of this study was to examine the predictive value of ECG QT interval and T-wave morphology parameters for all-cause and cardiovascular mortality in the general population.

Complex T-wave morphology in body surface potential mapping in prediction of arrhythmic events in patients with acute myocardial infarction and cardiac dysfunction.

Aims: Heterogeneous ventricular repolarization is associated with sudden cardiac death after myocardial infarction (MI). This prospective study investigated repolarization disparity with parameters based on T-wave morphology in body surface potential mapping (BSPM) in the assessment of arrhythmia risk in patients with a recent MI and cardiac dysfunction.

Methods And Results: Patients (n = 158) had 120-lead BSPM and 12-lead electrocardiogram (ECG) registered soon after acute MI.