Standard 12-lead ECG Recordings Research Articles

Differences in Brugada Syndrome Patients Through Ventricular Repolarization Analysis During Sleep.

Brugada syndrome (BS) is a genetic pathology that might cause sudden cardiac death (SCD) in patients with a structurally normal heart. Repolarization disorders have been postulated as a potential substrate for triggering cardiac arrhythmia in BS, that usually occur at rest or during sleep. In this paper, we have characterized ventricular repolarization markers during sleep on patients suffering from BS. To this end, standard 12-lead ECG recordings were analyzed in a population of 110 BS patients (25 symptomatic). The QT and the T-wave peak to T-wave end intervals (respectively QT and Tpe) were assessed from lead V5. The linear relationship between these markers and the instantaneous heart rate period (RR interval) are determined during each hour and for the whole sleep period. From the models obtained, corrected QT and Tpe measures were then estimated for each patient at 60 beats/min (QT60 and Tpe60) and at the mean heart rate observed during the involved time interval (QTHR and TpeHR). Results show larger values for symptomatic patients in all markers, with significant differences with respect to the asymptomatic group in the case of Tpe (Tpe60: p = 0.0012; TpeHR: p = 0.0014). Moreover, the temporal profiles of these markers reveal major differences among BS subgroups during the last 3 hours of sleep, where symptomatic patients presented increased QT60/HR (p = 0.01) and Tpe60/HR (p <; 0.001), as compared to the initial sleep hours. We conclude that BS patients present different repolarization properties according to their symptomatology, especially during the final stage of sleep.

Towards the clinical use of concentric electrodes in ECG recordings: influence of ring dimensions and electrode position

To overcome the limited spatial resolution of standard 12-lead ECG recordings, concentric ring electrodes (CRE) have been proposed to provide valuable data for the diagnosis of a wide range of cardiac abnormalities, including infarction and arrhythmia. Although theoretical studies indicate that the dimensions of the CRE regulate the depth of the electric dipoles sensed by these electrodes, this has not been experimentally confirmed. The aim of this work was to analyze the influence of CRE dimensions and position of a wireless multi-CRE sensor node on the cardiac signal recorded. For this, four wireless multichannel ECG recording nodes based on flexible multi-ring electrodes were placed at positions CMV1 (position comparable to V1), CMV2, CMV4R and CMV5; each node providing three bipolar concentric ECG signals (BC-ECG). Standard 12-lead ECG and 12 BC-ECG signals were recorded in 29 volunteers. The results revealed that a ring with an outer diameter of 33.5 mm achieves a balance between the ease-of-use and spatial resolution of smaller electrodes and improved detectability and higher amplitudes of signals from larger ring electrodes. Although a standard 12-lead ECG outperforms BC-ECC recordings in detectability of cardiac waves, if the relative amplitude of the wave is also considered, BC-ECG at CMV1 proved superior at picking up atrial activity. In fact, in most of the BC-ECG signals picked up at CMV1, P1 and P2 atrial activity waves were more clearly identified than in simultaneous 12-Lead ECG signals. Likewise, BC-ECG signals revealed higher spatial resolution in detecting anomalous electrical activity in local regions, such as impaired intraventricular driving, or atrioventricular blocks. Finally, the wireless multi-CRE sensor node provides enhanced comfort and handling to both patient and clinician over wired systems.

Dynamic changes of repolarization abnormalities in takotsubo cardiomyopathy

Objective This study analyses dynamic changes in dispersion of ventricular repolarization over the time course of takotsubo cardiomyopathy (TC), and their relationships with clinical features and life-threatening arrhythmias.Methods and results All consecutive patients admitted to our division between January 2008 and December 2011 with a diagnosis of TC were analysed. Patients with prior myocardial infarction, symptoms-onset-to-admission time greater than 12 hours, an implanted pacemaker, or under treatment with drugs aff ecting QT interval, were excluded. Standard 12-lead ECG recordings during the acute, subacute and chronic phases were collected for each patient. Twentyfour patients (23 women, 63 ± 14 years) were included in our analysis. Only one patient experienced ventricular arrhythmias (4.2%). Signifi cant increases were observed in QT and QTc intervals (from 420 ± 423 to 505 ± 66 ms, P < 0.00001, and from 479 ± 33 to 551 ± 51 ms, P < 0.00001, respectively), QT dispersion (from 59 ± 18 to 100 ± 44 ms, P = 0.0006), Tpeak-to-Tend (from 82 ± 20 to 123 ± 39 ms, P = 0.00006) and Tpeak-to-Tend/QT (from 0.20 ± 0.33 to 0.26 ± 0.57, P = 0.0003) during the subacute phase. All these parameters returned to baseline values in the chronic phase and did not show any signifi cant diff erences between the acute and chronic phases.Conclusions A marked increase in QTc, QT dispersion, Tpeak-to-Tend and Tpeak-to-Tend/QT was observed during the subacute phase; this increase was transient and reverted in all patients before hospital discharge. Of note, these fi ndings were not associated with an increased risk of life-threatening arrhythmias.

The acute effects of palonosetron on ECG parameters in patients with cancer.

e19693 Background: Serotonin receptor (5HT3) antagonists like dolasetron, ondansetron, granisetron and tropisetron have shown to cause QT prolongation. However, there is few data about palonosetron-related cardiac side effects. In this study, we aimed to determine the acute effects of palonosetron on QT interval, heart rate and arterial blood pressure. Methods: 101 cancer patients (51 female, 50 male) were enrolled to the study. Pts with acute ischemic heart disease and arrhythmia were excluded. Pts received 0.25 mg of palonosetron for prevention of chemotherapy-induced emesis. Standard 12-lead ECG recordings, heart rate (HR) and blood pressure (BP) measurements were performed at baseline, 30 minutes and 60 minutes after the palonosetron administration. By using Bazzet Formula, corrected QT interval (QTc) and QT dispersion (QTd) were calculated. Results: The mean age of pts was 54 ±13 years. In whole patient group, there were no differences in QTc, QTd measurements at 30 and 60 minutes after palonosetron injection when compared to baseline measurements. However, HR significantly decreased at 30 and 60 minutes after palonosetron injection. Compared with the baseline, systolic BP decreased nonsignificantly at 30 minute and then returned to baseline levels at 60 minute after palonosetron administration. When body surface area was taken into consideration, patients who received palonosetron over a dose of 0.13 mg/m2 had a decrease of QTc, HR and systolic BP at 30 minute and increase of these parameters at 60 minute. Conclusions: Palonosetron does not cause QT prolongation in standard doses, but causes a decrease in heart rate. Although there is no significant risk of QT prolongation with palonosetron, caution should be taken when QT prolonging drugs are used concomitantly and in patients with long QT syndrome. The routine administration of the drug at a fixed dose without any adjustment for body weight and body surface area can increase the risk of cardiac side effects in lean patients.

The acute effect of palonosetron on ECG parameters in patients with cancer.

e19686 Background: The 5-hydroxytryptamine 3 receptor antagonists are used for the prevention and treatment of chemotherpy and radiotherapy-induced emesis. Despite their effectiveness and safety profile, it was reported in many studies that they may cause electrocardiographic changes related to heart rate and repolarization. The purpose of this study is to determine acute influence of paronosetron on ECG parameters in cancer patients. Methods: Forty-seven cancer patients with normal cardiac function who received paronosetron for the prevention of chemotherapy/radiotherapy induced emesis were enrolled into this prospective study. Standard 12-lead ECG recordings were performed at baseline and 30 min after palonosetron administration. P wave durations and corrected QT intervals were measured; P wave dispersion (Pd) and QTc dispersion were calculated. Statistical comparison of quantitative data was performed by paired sample t test. A P value of <0.05 was considered to be statistically significant. Results: In comparison with baseline, no statistically significant change in any ECG parameters, including QT and RR intervals, P wave durations, Pd and QTd, was observed after infusion of Palonosetron. Conclusions: In this study palonosetron did not show any ventricular and atrial arrhythmogenic effect because of repolarization abnormalities.

Zoledronic acid and atrial fibrillation in cancer patients

Treatment with a bisphosphonate was found to be associated with a significantly increased risk for atrial fibrillation (AF) in a few studies. A recent study showed that once-yearly infusions of intravenous zoledronic acid (ZA) significantly increased the risk of serious AF in postmenopausal women with osteoporosis. This study was conducted to determine the frequency of atrial fibrillation among cancer patients receiving the standard treatment of ZA. Patients with bone metastases who presented to our outpatient clinic for any reason (routine control, chemotherapy, or ZA administration) were included in the study. All patients had been receiving 4 mg ZA at 4-week intervals, with each dose administered over 15 min. A short survey was completed and standard 12-lead ECG recordings were obtained. One hundred and twenty-four cancer patients with documented bone metastases were evaluated. Mean age of the patients was 55 ± 13.0 years, 60% of the patients were female. Forty-one percent of the patients had breast cancer, 18% had non-small cell lung cancer, and the remainder had other solid tumors. Mean duration of ZA administration was 13.4 ± 15.0 months. Mean total cumulative dose was 54 ± 15.0 mg per patient. Sixty patients (48%) had previously been treated with anthracycline-containing regimens, and 37 (30%) had received chest radiotherapy that might affect the heart. Twenty-three percent of the patients had hypertension, 10% had diabetes mellitus, 3.7% had myocardial infarction history, 1.9% had congestive heart failure, and 1% had valvular disease; 10.5% were current smokers and 32% ex-smokers. On ECG evaluation, we observed normal sinus rhythm in 58%, sinus tachycardia in 15%, sinus bradicardia in 3.2%, and ventricular extrasystole in 5.7% of the patients. There was no AF in any of the cases. There was no increase in the risk of AF frequency in cancer patients who were treated with intravenous ZA, although most of the patients had additional risk factors including previous treatment with cardiotoxic agents or with chest radiotherapy. We believe that the risk of AF is negligible in this patient population and does not affect treatment decisions.

Bayesian Approach to Patient-Tailored Vectorcardiography

For assessment of specific cardiac pathologies, vectorcardiography is generally considered superior with respect to electrocardiography. Existing vectorcardiography methods operate by calculating the vectorcardiogram (VCG) as a fixed linear combination of ECG signals. These methods, with the inverse Dower matrix method the current standard, are therefore not flexible with respect to different body compositions and geometries. Hence, they cannot be applied with accuracy on patients that do not conform to the fixed standard. Typical examples of such patients are obese patients or fetuses. For the latter category, when recording the fetal ECG from the maternal abdomen the distance of the fetal heart with respect to the electrodes is unknown. Consequently, also the signal attenuation/transformation per electrode is not known. In this paper, a Bayesian method is developed that estimates the VCG and, to some extent, also the signal attenuation in multichannel ECG recordings from either the adult 12-lead ECG or the maternal abdomen. This is done by determining for which VCG and signal attenuation the joint probability over both these variables is maximal given the observed ECG signals. The underlying joint probability distribution is determined by assuming the ECG signals to originate from scaled VCG projections and additive noise. With this method, a VCG, tailored to each specific patient, is determined. The method is compared to the inverse Dower matrix method by applying both methods on standard 12-lead ECG recordings and evaluating the performance in predicting ECG signals from the determined VCG. In addition, to model nonstandard patients, the 12-lead ECG signals are randomly scaled and, once more, the performance in predicting ECG signals from the VCG is compared between both methods. Finally, both methods are also compared on fetal ECG signals that are obtained from the maternal abdomen. For patients conforming to the standard, both methods perform similarly, with the developed method performing marginally better. For scaled ECG signals and fetal ECG signals, the developed method significantly outperforms the inverse Dower matrix method.

Zoledronic acid and atrial fibrillation in cancer patients with bone metastases

e20591 Background: Treatment with a bisphosphonate was linked with a significantly increased risk for atrial fibrillation (AF) in a few studies. Once-yearly infusions of intravenous zoledronic acid (ZA) was also significantly increased serious AF in postmenopausal women with osteoporosis. This study was conducted to determine the frequency of atrial fibrillation among cancer patients receiving the standard treatment of ZA. Methods: One hundred and twenty-four cancer patients who had bone metastasis receiving ZA were included in this study. All patients have been receiving 4 mg ZA at 4-week intervals; with each dose administered over 15 minutes. Patients who presented outpatient clinic for any reason (routine control, chemotherapy, ZA administration) a short survey completed and standard 12-lead ECG recordings were obtained. Results: One hundred and twenty-four cancer patients with documented bone metastases were evaluated. Mean age of the patients was 55 ± 13.0 years, 60% of the patients were female. Forty-one percent of the patients had breast cancer and 17% non-small cell lung cancer and the remainder had other solid tumors. Mean duration of ZA administration was 13.4 ± 15.0 months/patients. Mean total cumulative dose was 54 ± 15.0 mg per patients. 60 (48%) of the patients were treated with antracycline including regimens, and 37 (30%) were treated with mediastinal radiotherapy that might effect the heart. Twenty-three percent of the patients had hypertension, 10% diabetes mellitus, 7% currently smoker and 32% exsmoker, 3.7% myocardial infarction history, 1.9% congestive heart failure, and 1% valvular disease. On ECG evaluation; we observed sinus rhythm in 58%, sinus tachycardia in 15%, sinus bradicardia in 3.2%, ventricular exracystole in 5.7% of the patients. There were no AF. Conclusions: Although most of the patients were also having potentially cardiotoxic treatment, there was no increase in AF frequency in cancer patients who were treated with intravenous ZA. We believe that the risk of AF is small and may increase with age and comorbidity. No significant financial relationships to disclose.

The acute effect of tropisetron on ECG parameters in cancer patients

The 5-hydroxytryptamine 3 receptor antagonists, including tropisetron, ondansetron, granisetron, and dolasetron are agents used effectively for supportive care. They are used for the prevention and treatment of chemotherapy and radiotherapy-induced emesis. Despite their overall excellent safety profile, some electrocardiographic changes related to heart rate and repolarization were reported. Ondansetron, granisetron, and dolasetron were studied on this manner. But to our knowledge, there is no information about the cardiac side effects of tropisetron. In this study, we aimed to determine the acute effects of tropisetron on ECG parameters related to repolarization, heart rate, and systemic blood pressure. Fifty-five cancer patients who received tropisetron for the prevention of acute chemotherapy-induced nausea and vomiting were enrolled into this single center, prospective study. Standard 12-lead ECG recordings were performed at baseline and 30 min after tropisetron (5 mg given over 1 min IV bolus) administration. P wave durations and corrected QT intervals were measured; P wave dispersion and QTc dispersion were calculated. In comparison with baseline, mean heart rate significantly decreased 30 min after administration of tropisetron. Tropisetron did not result in a significant change in P wave duration, corrected QT interval, P dispersion, and QTc dispersion. In this study, tropisetron did not show any ventricular and atrial arrhythmogenic effect because of repolarization abnormalities. Only it may cause a slight decrease in heart rate.

Impacts of Glycoprotein IIb/IIIa Inhibition on QT Dispersion After Successful Percutaneous Coronary Intervention

Coronary ischemia augments inhomogeneity in ventricular repolarization. Decrease in the QT dispersion (QTd) following restoration of coronary blood flow to the ischemic myocardium by successful percutaneous coronary intervention (PCI) is an expected outcome. The purpose of the study was to seek whether glycoprotein IIb/IIIa (GP IIb/IIIa) inhibition has additional beneficial effects on QT dispersion after angiographically successful PCI. The study involved 111 consecutive patients scheduled for elective coronary balloon angioplasty with or without stent implantation. Sixty patients (mean age 58 +/-9) were randomized to receive standard therapy including preprocedural aspirin, ticlopidine, and IV heparin, and 51 patients (mean age 54 +/-10) were randomized to receive additional IV tirofiban infusion before the lesion was crossed with the guidewire. Standard 12-lead simultaneous ECG recordings for the measurement of QTd and corrected QTd (QTcd) (calculated by using Bazett's formula) were obtained before and immediately after the procedure, and at the 6th, and 24th hours. Blood samples for detection of postprocedural myocardial damage (CK-MB and cTn-I) were taken before and immediately after the procedure, at the 6th, 12th, and 24th hours. In total, 128 stenoses were treated with PCI. Seventy of these lesions were in the standard therapy group and 58 in the tirofiban group. QTd and QTcd were not statistically different between the 2 groups before and immediately after the procedure and at the 6th hours, but at the 24th hour QTd and QTcd were significantly longer in the standard therapy group (p=0.047 and p=0.001, respectively). Postprocedural troponin-I elevation (B=0.692, p=0.037), maximum inflation pressure (B=0.182, p=0.001), and previous myocardial infarction (MI) (B=0.885, p=0.004) were defined as the predictors of the final QT dispersion at the 24th hour. QT dispersion significantly decreased after successful percutaneous coronary intervention. GP IIb/IIIa inhibition therapy was not superior by means of recovery of increased QT dispersion during the early hours of the intervention, but it prevented minor myocardial necrosis and provided more long-lasting recovery in QT dispersion as compared with heparin therapy. This impact of GP IIb/IIIa receptor inhibition on QTd may be a possible mechanism by which these drugs reduce cardiovascular events after PCI.

Relationship between Antidiabetic Treatment with QT Dispersion During Acute Coronary Syndromes in Type 2 Diabetes: Comparison between Patients Receiving Sulfonylureas and Insulin

Patients with acute coronary syndromes (ACS) show prolongation of QT interval duration and its dispersion (QTd). Prolongation of QTd has been associated with inhomogeneity of ventricular recovery times and high arrhythmyogenic potential. Previous studies have shown that preservation of the ischaemic preconditioning is associated with shorter QTd. Sulfonylureas may inhibit cardiac ischaemic preconditioning. The effect, however, of the previous treatment with sulfonylureas on QTd in patients with ACS has not been studied so far. This cross-sectional study examined the effect of the previous antidiabetic treatment on QTd in patients with type 2 diabetes during ACS. A total of 150 patients with ACS (myocardial infarction: n = 120; unstable angina: n = 30) admitted to the coronary care unit of our hospital were studied. Three groups of patients were examined: patients without diabetes (n = 60); patients with type 2 diabetes treated with sulfonylureas alone or in combination with metformin (n = 50); and patients treated with insulin alone or in combination with metformin (n = 40). Standard 12-lead ECG recordings at admission to the coronary care unit were obtained. QT interval duration and QTd were measured using ECG analysis software. At admission, QTd was not different between diabetic and non-diabetic patients (72.1 +/- 21.7 vs. 78.4 +/- 21.3 msec, p = 0.13, respectively). Similarly, the values of the above interval were also not different between patients with type 2 diabetes treated with sulfonylureas and insulin (73.8 +/- 23.9 vs. 70.1 +/- 18.5 msec, p = 0.55, respectively). It is concluded that the previous treatment with either sulfonylureas or insulin does not affect QTd in patients with type 2 diabetes and ACS.