The effect of intracoronary sodium nitrite on the burden of ventricular arrhythmias following primary percutaneous coronary intervention for acute myocardial infarction

OBJECTIVE

Pre-clinical evidence suggests delivery of nitric oxide (NO) through administration of inorganic nitrite suppresses arrhythmias resulting from acute ischaemia and reperfusion (I/R). To date no assessment of whether inorganic nitrite might limit reperfusion arrhythmia has occurred in man, therefore we explored the effects on I/R-induced ventricular arrhythmias in the NITRITE-AMI cohort.

METHODS

In the NITRITE-AMI cohort, Holter analysis was performed prior to and for 24 h after primary PCI in 80 patients who received either intra-coronary sodium nitrite (N = 40) or placebo (N = 40) during primary PCI for AMI.

RESULTS

Ventricular rhythm disturbance was experienced by 100% patients; however, there was no difference in the number between the groups, p = .2196. Non-sustained ventricular tachycardia (NSVT) occurred in 67.5% (27/40) of nitrite-treated patients compared to 89% (35/39) of those treated with placebo (p = .027). There was a significant reduction in both the number of runs (63%, p ≤.0001) and total beats of NSVT (64%, p = .0019) in the nitrite-treated patients compared to placebo. Post-hoc analyses demonstrate a direct correlation of occurrence of NSVT with infarct size, with the correlation stronger in the placebo versus the nitrite group initiating an independent nitrite effect (Nitrite: r = 0.110, p = .499, placebo: r = 0.527, p = .001, p for comparison: 0.004).

CONCLUSION

Overall no difference in ventricular rhythm disturbance was seen with intra-coronary nitrite treatment during primary PCI in STEMI patients, however nitrite treatment was associated with an important reduction in the incidence and severity of NSVT. In view of the sustained reduction of MACE seen, this effect warrants further study in a large-scale trial.

Comparison of treatment outcomes between convergent procedure and catheter ablation for paroxysmal atrial fibrillation evaluated with implantable loop recorder monitoring

INTRODUCTION

While catheter ablation (CA) is an established treatment for symptomatic paroxysmal atrial fibrillation (AF), convergent epicardial and endocardial ablation procedure (CVP) has been primarily used to treat persistent AF. The aim of this single-center, prospective, randomized study was to compare treatment efficacy of CA and CVP in paroxysmal AF patients by monitoring AF, atrial tachycardia (AT), and atrial flutter (AFL) recurrence with Implantable Loop Recorder (ILR).

METHODS AND RESULTS

Fifty patients (74% male) with history of paroxysmal AF were randomized between CA and CVP. Outcomes were determined by ILRs; every episode of AF/AT/AFL lasting 6 minutes or more was defined as a recurrence. AF burden (AFB) and required AF reinterventions (cardioversions and repeat ablations) were quantified after a 3-month blanking period. Total procedural (266 ± 44 vs. 242 ± 39 minutes) and ablation duration (52 ± 10 vs. 48 ± 12 minutes) was similar in both groups. Recurrence of AF/AT/AFL was more likely in the CA group compared to the CVP group (OR 3.78 (95% CI (1.17, 12.19), P  =  0.048)). During the follow-up period (mean 30.5 ± 6.9 months), higher AF burden and more reinterventions for recurrent AF were recorded in the CA group. There were more periprocedural complications in the CVP group (12.5%) compared to the CA group (0%).

CONCLUSION

Treatment of paroxysmal AF with CVP showed less arrhythmia recurrence compared to CA. In addition, patients after CVP had fewer reinterventions and lower AF burden, but more periprocedural complications.

Wearable technology for cardiology: An update and framework for the future

The field of cardiology has long used wearable medical devices to monitor heart rate and rhythm. The past decade has seen the emergence of many new wearable devices, including several that have been widely adopted by both physicians and consumers. In this review, we discuss existing and forthcoming devices designed to measure activity, heart rate, heart rhythm, and thoracic fluid. We also offer several frameworks to classify and better understand wearable devices, such that we may weigh their potential benefit in improving healthcare with the many challenges that must be addressed to reap these benefits.

Current rare indications and future directions for implantable loop recorders

The scope of application for implantable loop recorders has shifted away from the evaluation of unclear palpitations and syncope episodes to more complex conditions. This article focuses on rare indications of growing importance such as rhythm monitoring after ablation of atrial fibrillation or after cryptogenic stroke. Furthermore, forthcoming applications in various clinical settings are described, e. g., arrhythmia detection after myocardial infarction, after catheter-based valve interventions, in heart failure, and in cardiomyopathies. Enhancement of the capabilities of implantable loop recorders could broaden their fields of use.

[Clinical development of the automatic implantable defibrillator over 35 years: A success story]

After 12 years of development and experimental evaluation, the first automatic implantable cardioverter-defibrillator (ICD) was implanted in man on February 4, 1980. This overview describes the technical and functional developments over 35 years from a simple shock-box, weighing 292 g, to the sophisticated 80 g device of today, delivering graded therapy to sustained ventricular arrhythmias and biventricular stimulation to treat heart failure. Finally, a special tribute is given to Michel Mirowski, one of the inventors of the ICD, as scientist and physician dedicated to patient care.

12-lead Holter electrocardiography. Review of the literature and clinical application update

This brief review is focused on 12-lead Holter electrocardiogram (ECG) recording including a review of the literature and the description of the advantages of its application. The standard 12-lead ECG provides a bedside snapshot of the electrical activity of the heart including vector information, but a snapshot of a few beats for some seconds might miss the whole story. Traditional Holter ECG displaying two or three leads may record all heart beats during a prolonged period, but the limited vector information might be a cause of shortcomings in the ECG diagnosis. The 12-lead Holter ECG overcomes these disadvantages and should be preferred for detecting episodes of arrhythmias, localize their origin or the localization of myocardial ischemia. The 12-lead Holter ECG monitoring is efficient in the evaluation of the effect of drugs or interventional therapeutic procedures, i.e., efficiency of biventricular pacing in patients with heart failure and permanent atrial fibrillation (AF). The automatic analysis of parameters in 12-lead Holter ECG is also providing information for risk stratification. In order to obtain a precise diagnosis based on the criteria established on standard ECG, the "real" 12-lead ECG with ten electrodes is advocated.

[Development of dynamic ECG acquisition and recording system: review and prospect]

Dynamic electrocardiography (DCG) or Holter is the best device to detect arrhythmia and can help early detection of some sudden cardiac death risk factors. The acquisition and recording system of the DCG, however, affects the data quality and the patients' comfort directly. This paper reviews the related latest studies, and discusses the importance of new ECG electrode and wireless dynamic monitoring in DCG monitoring field. Moreover, the existed main problems are summarized and classified and the prospects for the development trend are presented.

[Remote control in ICD therapy]

In several studies, ICD therapy has been shown to be an effective treatment option for patients suffering from or being at risk of malignant ventricular arrhythmias. Given the increasing rate of ICD implantations with the need for in-office interrogations at least twice a year, the number of follow-up visits is constantly growing. Remote transmission of relevant ICD data is a way to reduce follow-up burden for the physician, travel costs for the patient, and the time delay between onset of medical or device problems and an adequate physician response. In several studies, it has been demonstrated that remote ICD follow-up is safe and reduces follow-up resources for both the patient and the physician. With ongoing studies, the questions of whether remote ICD interrogations can offer additional diagnostic and therapeutic options that go beyond pure device follow-up and allow for a more complex management of ICD patients, who in fact represent a large percentage of the heart failure population, will have to be answered.

[Long term electrocardiography (Holter monitoring)]

During the past almost 50 years Holter monitoring has become an established non-invasive diagnostic tool in clinical electrophysiology. It allows ECG recording independent of stationary monitoring facilities during daily life and, therefore, contains much information. In the beginning the main interest was directed towards quantitative and qualitative assessment of arrhythmias, their circadian behaviour, and the circadian behaviour of the heart rate. With advances in technology the analysis spectrum of Holter monitoring expanded, and it was used also for detection of silent myocardial ischaemia. New digital recorders and computers with large capacities made it possible to measure every single heart beat very accurately, which was a prerequisite for heart rate variability and QT-interval analysis, which provided new knowledge about the autonomic modulation of the heart rate and the circadian dynamicity of the QT interval, respectively. Beyond arrhythmia analysis Holter monitoring was increasingly used to assess prognosis in different cardiac conditions. It can also be valuable in assessing transient symptoms possibly related to arrhythmias or device dysfunction, which will not necessarily be revealed by simple device control.

Home Monitoring: what can we expect in the future?

The Home Monitoring of implanted cardiac rhythm management devices developed by Biotronik (Berlin, Germany) is a new useful tool for monitoring patients. Home Monitoring provides access to technical and clinical data, allowing almost continuous patient surveillance. The implanted defibrillators and pacemakers transmit encrypted messages, which are automatically analyzed in the Home Monitoring Service Center and sent to the physician. The expected benefit of this kind of data transmission is an improvement in patient follow-up and early detection of changes in the rhythmologic state of the patient. However, these new tools raise several questions, which will require an answer in the nearest future. These questions focus on safety and economic aspects, and on the liability of the physician and the manufacturer. Technological improvement is also expected.

Assessment of the classification capability of prediction and approximation methods for HRV analysis

The goal of this paper is to examine the classification capabilities of various prediction and approximation methods and suggest which are most likely to be suitable for the clinical setting. Various prediction and approximation methods are applied in order to detect and extract those which provide the better differentiation between control and patient data, as well as members of different age groups. The prediction methods are local linear prediction, local exponential prediction, the delay times method, autoregressive prediction and neural networks. Approximation is computed with local linear approximation, least squares approximation, neural networks and the wavelet transform. These methods are chosen since each has a different physical basis and thus extracts and uses time series information in a different way.

Developments in ambulatory electrocardiography

Cardiovascular disease (CVD) is the leading cause of death in many developed countries. There is a need for cardiovascular monitoring devices that can supplement traditional medical and clinical care by enabling the diagnosis of conditions with infrequent symptoms, the timely detection of critical signs that are precursors to sudden cardiac death, and the long-term management of chronic conditions through monitoring of symptoms, risk factors, and the effects of therapy. This paper provides an overview of ambulatory electrocardiogram (ECG) monitors, which are one of the most widely prescribed diagnostic procedures for cardiovascular disease. The engineering challenges associated with ambulatory electrocardiography are discussed, and technological improvement areas that are the focus of current research effort are reviewed.

[Home Monitoring with implantable ICD--a diagnostic innovation?]

In recent years the rate of ICD implantation has grown substantially after the results of primary and secondary prevention trails have shown significant improvement in mortality and morbidity. However, the increasing number of patients with ICD indication leaves the implanting centres with large logistic problems, esp. with the number of follow-up visits. To further ensure high quality standard in therapy management new follow up routines have to be considered. Possible help may come with new methods of telecardiology, which are presently being introduced into clinical practice. Those systems differ in the way that they are capable to substitute a routine follow up and/ or deliver continuous diagnostic and device status information. Maybe the most promising solution is Home Monitoring in which the implant sends automatically daily messages with regard to therapy and ICD/CRT status without any cooperation of the patient. Interaction of the physician can be triggered by patient individual event filter. By utilizing this features in combination with event related IEGM Online Data physician are able to guide patients more effectively.

[The technical possibilities in telemonitoring of physiological parameters]

For decades, telemonitoring of vital parameters has been a recurring topic among experts. Because of its lack of economical advantages it has not established itself as a standard up to now. Thanks to novel wireless communication technologies such as Bluetooth or Zigbee, the enormous technological progress in mobile communication via GSM, GPRS, as well as UMTS and various radical medical changes within disease management programs, currently very promising new potentials for telemonitoring are appearing. This article summarizes the current technological developments, discusses their advantages and drawbacks, and deduces scenarios and technical requirements for future system architectures.

New horizons in ambulatory electroencephalography

Since its inception 30 years ago, AEEG has continued to evolve--from four-channel tape recorders to 32-channel digital recorders with sophisticated automatic spike and seizure detection algorithms. AEEG remains an important tool in epilepsy evaluation. In the near future, smaller, faster, and more sophisticated AEEGs will be developed. Seizure detection/anticipation systems will allow the wearer to be forewarned of a seizure so that appropriate safety measures can be taken. With further refinement in our understanding of nonlinear dynamic analysis to define the pre-ictal state, AEEG will be coupled with an accurate seizure anticipation device in a closed-loop system, providing a time window during which therapeutic intervention can occur, to prevent a seizure. The therapeutic intervention will most likely involve vagus nerve or deep brain stimulation. An alternative is that the patient may learn to recognize early symptoms of the pre-ictal state and use behavioral biofeedback interventions to avoid a clinical seizure. In order to achieve convenient ambulatory recording and seizure detection that could realistically improve the lives of patients with refractory epilepsy, the process of miniaturization of such a device to a convenient size must be accomplished. One of the aspects of epilepsy that patients find most frustrating, and that most limits activities, is the vulnerability to sudden unexpected incapacitation due to the occurrence of a seizure. With miniaturization of AEEG and seizure anticipation technology, and advancements in our ability to identify the transition from pre-ictal to ictal state, there is realistic hope that patients with refractory epilepsy may gain control over their seizures and enjoy significantly improved quality of life.

Advances in modern electrocardiographic equipment for long-term ambulatory monitoring

Electrocardiographic ambulatory "Holter" monitoring (AECG) is an essential tool in the diagnostic evaluation of patients with cardiac arrhythmias. Recent advances in digital Holter technology have improved the quality of the ECG signals and new dedicated algorithms have expanded the clinical application of software-based AECG analysis systems. Due to the availability of inexpensive large storage capacities, very long-term (weeks to months) continuous high-quality AECG monitoring will soon be available, together with devices for long-term long-distance telemetric surveillance for high-risk cardiac patients, utilizing trans-telephonic transmission of ECG data. New digital recorders will also have the capability for multichannel simultaneous recordings (currently from 3 to 8 simultaneous leads). Multichannel digital recordings will allow the recording of different biological signals by appropriate sensors, such as respiratory frequency, peripheral oxygen tension, arterial pulse pressure, EEG, and others. This will transform conventional AECG in ambulatory policardiography, allowing the comprehensive evaluation of patients with complex disorders, such as heart failure or sleep apnea syndromes. By this global approach, Holter analysis becomes a real "noninvasive electrophysiological test," to identify potential risk factors for life-threatening cardiac arrhythmias.

[ECG Holter monitoring in the detection of cardiac arrhythmias yesterday, today and tomorrow]

The paper summarizes contemporary knowledge and technical possibilities of the use of Holter systems of 24-hour and long-term ECG monitoring in the diagnosis of cardiac arrhythmias. It evaluates the development of different types of equipment and indications for their use. It summarizes the yield of different types and mentions detailed limitations for their use and deals with the economic evaluation of different methods. Finally it summarizes contemporary technical possibilities and future perspectives such as transmission of data over the internet and combination of ECG monitoring with other non-invasive examinations.

[Holter monitoring in 2000]

Ambulatory 24 hour monitoring was developed in the United States and bears the name of its inventor, Holter. It was introduced in France for the first time by the Lariboisière school, 25 years ago, and the end of the year 2000 is an appropriate time to review this tool. What are the new clinical indications, technical progress and prospects for the future? All the efforts of both cardiologists and engineers for the past 25 years have been focused on gathering information about the system of cardiac regulation which is more or less concealed in the ECG recordings. As far as arrhythmias are concerned, or the QRS or T wave morphology, or the circadian variations of sinus rate and depolarisation, the studies are numerous but not always easily applicable in clinical practice. However, the non-invasive analysis given by the Holter recording guarantees a promising future in terms of new discoveries and applications.

Present and future role of ambulatory Holter monitoring for arrhythmia risk stratification

Risk stratification for arrhythmogenic events and sudden death in patients with organic heart disease, particularly those with coronary heart disease and a history of MI, continues to be one of the major tasks of clinical cardiologists, although advanced management strategies including thrombolysis, acute PTCA and surgical intervention dramatically reduced the percentage of sudden deaths following acute MIs, Noninvasive studies like resting and exercise ECG, echocardiography, signal averaging, 24-hour ECG, and radionuclide studies, as well as invasive techniques such as electrophysiologically programmed electrostimulation and coronary angiography, are being used routinely. Ambulatory Holter monitoring is an established noninvasive technique for risk stratification. There is evidence showing that its predictive potential for arrhythmogenic risks is enhanced, if more than one parameter is analyzed. Absence of ST segment changes and a normal HRV are the parameters signaling out low-risk patients. The use of additional parameters which escape electrocardiographic recording, like ventricular function and myocardial ischemia, improve the accuracy of predicting arrhythmogenic events. The most predictive combination of risk parameters is, however, still poorly understood. Future research should define normal ranges of parameters recordable by H-ECG, solve technical problems of recording data and analyzing them. In addition, the accuracy of measuring QT duration and documenting late potentials should be improved by more sophisticated methods. But it is unrealistic to expect that the QT interval will become amenable to automatic analysis in all patients. A fully automatic QT analysis without visually checking the measuring points at the tip and the end of the T wave for their consistency is hardly conceivable. The documentation of late potentials, in turn, is limited by artefacts caused by muscle contraction during physical activity. Clinical aspects, e.g., the predictability of arrhythmogenic events in patients with cardiomyopathies and valvular disease should be addressed. This will require studies combining the predictive potentials of rhythmologic and hemodynamic data.

An audit of utilisation of Holter tape facilities at Glasgow Royal Infirmary

Holter tape analysis is widely used to both confirm and exclude the presence of significant arrhythmias. We have studied the utilisation of the Holter service at Glasgow Royal Infirmary over a period of 6 months. During this period 305 x 24 hour Holter tapes were recorded. Out patient referrals generated 95% of these requests with only 5% of requests for in patient recordings. The median delay from request date to dispatch to the referring doctor was 14 days. No arrhythmia was detected in 77% and only 3% had a detectable symptomatic significant arrhythmia. The recording was felt to demonstrate the presence of a relevant arrhythmia in 17% of cases and to help exclude a possible arrhythmia in 61%. The capital cost per tape was 20.82 Pounds. In conclusion Holter monitoring is an inexpensive way of analysing the heart rhythm over an extended period which is probably underused.