False-positive stress testing: Does endothelial vascular dysfunction contribute to ST-segment depression in women? A pilot study.

Background: The utility of exercise-induced ST-segment depression for diagnosing ischemic heart disease (IHD) in women is unclear.

Hypothesis: Based on evidence that IHD pathophysiology in women involves coronary vascular dysfunction, we hypothesized that coronary vascular dysfunction contributes to exercise electrocardiography (Ex-ECG) ST-depression in the absence of obstructive coronary artery disease, so-called false positive results. We tested our hypothesis in a pilot study evaluating the relationship between peripheral vascular endothelial function and Ex-ECG.

Localization of premature ventricular contractions from the papillary muscles using the standard 12-lead electrocardiogram: a feasibility study using a novel cardiac isochrone positioning system.

Aims: The precise localization of the site of origin of a premature ventricular contraction (PVC) prior to ablation can facilitate the planning and execution of the electrophysiological procedure. In clinical practice, the targeted ablation site is estimated from the standard 12-lead ECG. The accuracy of this qualitative estimation has limitations, particularly in the localization of PVCs originating from the papillary muscles.

Development of new anatomy reconstruction software to localize cardiac isochrones to the cardiac surface from the 12 lead ECG.

Non-invasive electrocardiographic imaging (ECGI) of the cardiac muscle can help the pre-procedure planning of the ablation of ventricular arrhythmias by reducing the time to localize the origin. Our non-invasive ECGI system, the cardiac isochrone positioning system (CIPS), requires non-intersecting meshes of the heart, lungs and torso. However, software to reconstruct the meshes of the heart, lungs and torso with the capability to check and prevent these intersections is currently lacking.

Sensitivity of CIPS-computed PVC location to measurement errors in ECG electrode position: the need for the 3D camera.

Background: The Cardiac Isochrone Positioning System (CIPS) is a non-invasive method able to localize the origins of PVCs, VT and WPW from the 12 lead ECG. The CIPS model integrates a standard 12-lead ECG with an MRI derived model of the heart, lungs, and torso in order to compute the precise electrical origin of a PVC from within the myocardium. To make these calculations, CIPS uses virtually represented ECG electrode positions.

Quantitative localization of premature ventricular contractions using myocardial activation ECGI from the standard 12-lead electrocardiogram.

Background: The precise localization of the site of origin of a premature ventricular contractions (PVC) prior to ablation would facilitate the planning and execution of the electrophysiological procedure. Current electrocardiographic imaging (ECGI) techniques require body surface maps, a costly and complex procedure, that requires as many as 256 leads to localize the PVC origin. We developed and tested a novel myocardial activation based ECGI technique utilizing the readily available 12-lead ECG to localize the PVC origin.

Modulation of regional dispersion of repolarization and T-peak to T-end interval by the right and left stellate ganglia.

Left stellate or right stellate ganglion stimulation (LGSG or RSGS, respectively) is associated with ventricular tachyarrhythmias; however, the electrophysiological mechanisms remain unclear. We assessed 1) regional dispersion of myocardial repolarization during RSGS and LSGS and 2) regional electrophysiological mechanisms underlying T-wave changes, including T-peak to T-end (Tp-e) interval, which are associated with ventricular tachyarrhythmia/ventricular fibrillation. In 10 pigs, a 56-electrode sock was placed around the heart, and both stellate ganglia were exposed.

New devices for very long-term ECG monitoring.

Present day 24-h Holter monitors have been shown to miss many arrhythmias that may occur infrequently or under specific circumstances. The advancement in electronic and adhesive technologies have enabled the development of first generation wearable long-term 14-day patch ECG monitors that attach directly to the skin and require no electrodes and wires to operate. This new technology is unobtrusive to the patients and offers them unprecedented mobility.

A new electrocardiographic marker for sympathetic nerve stimulation: modulation of repolarization by stimulation of stellate ganglia.

Activation of cardiac sympathetic nerves alters ventricular repolarization; however, these changes remain poorly characterized. The goal of this study was to examine effects of sympathetic stimulation on repolarization to identify electrocardiographic markers of sympathetic activation. Pigs underwent median sternotomy and bilateral thoracotomy to expose the stellate ganglia.

New material for implantable cardiac leads.

Unlabelled: Cardiac function management devices, including implantable pacemakers and implantable defibrillators, include at least 1 cardiac lead having an electrode for making contact with a portion of the heart. It has been previously shown that the braided multifilament wire electrodes have a high failure rate both for sensing of spontaneous heart activity and for safe heart stimulation. Therefore, it is desirable to have cardiac leads made of materials with mechanical and electrical properties to insure safe pacemaker function.

AHA scientific statement: practice standards for electrocardiographic monitoring in hospital settings: an American Heart Association Scientific Statement from the Councils on Cardiovascular Nursing, Clinical Cardiology, and Cardiovascular Disease in the Young: endorsed by the International Society of Computerized electrocardiology and the American Association of Critical-Care Nurses.

The goals of electrocardiographic (ECG) monitoring in hospital settings have expanded from simple heart rate and basic rhythm determination to the diagnosis of complex arrhythmias, myocardial ischemia, and prolonged QT interval. Whereas Computerized arrhythmia analysis is automatic in cardiac monitoring systems, computerized ST-segment ischemia analysis is available only in newer-generation monitors, and computerized QT-interval monitoring is currently unavailable. Even in hospitals with ST-monitoring capability, ischemia monitoring is vastly underutilized by healthcare professionals.

Practice standards for electrocardiographic monitoring in hospital settings: an American Heart Association scientific statement from the Councils on Cardiovascular Nursing, Clinical Cardiology, and Cardiovascular Disease in the Young: endorsed by the International Society of Computerized Electrocardiology and the American Association of Critical-Care Nurses.

The goals of electrocardiographic (ECG) monitoring in hospital settings have expanded from simple heart rate and basic rhythm determination to the diagnosis of complex arrhythmias, myocardial ischemia, and prolonged QT interval. Whereas computerized arrhythmia analysis is automatic in cardiac monitoring systems, computerized ST-segment ischemia analysis is available only in newer-generation monitors, and computerized QT-interval monitoring is currently unavailable. Even in hospitals with ST-monitoring capability, ischemia monitoring is vastly underutilized by healthcare professionals.

State of the art techniques for preservation and reuse of hard copy electrocardiograms.

Baseline examinations and periodic reexaminations in longitudinal population studies, together with ongoing surveillance for morbidity and mortality, provide unique opportunities for seeking ways to enhance the value of electrocardiography (ECG) as an inexpensive and noninvasive tool for prognosis and diagnosis. We used newly developed optical ECG waveform recognition (OEWR) technique capable of extracting raw waveform data from legacy hard copy ECG recording. Hardcopy ECG recordings were scanned and processed by the OEWR algorithm.

Time-dependent predictors of primary cardiac arrest in patients with acute myocardial infarction.

To understand predictors of cardiac arrest early in acute myocardial infarction (AMI), for the Thrombolytic Predictive Instrument, we developed a multivariable regression model predicting primary cardiac arrest using time-dependent variables based on a case-control study of emergency department (ED) patients with AMI: 65 cases with sudden cardiac arrest and 258 without cardiac arrest. Within the first hour of AMI symptom onset, adjusting for age, systolic blood pressure, serum potassium, and infarct size, increased risk of cardiac arrest was associated with electrocardiographic prolonged QTc interval and a greater sum of ST-segment elevation. After 1 hour, the effect of ST-segment elevation was much reduced and the effect of the QTc interval was reversed, so prolonged QTc appeared protective.