Identification Of Arrhythmias Research Articles

Holter Monitoring in Clinically Healthy Cavalier King Charles Spaniels, Wire‐Haired Dachshunds, and Cairn Terriers

Few reported studies describe normal values from 24-hour ECG (Holter) recordings of small breed dogs. To investigate influence of breed, age, sex, body weight, degree of recording artifact, and mitral valve prolapse (MVP) on Holter recordings of 3 breeds of small dogs that have differing predispositions for myxomatous mitral valve disease. The study also assessed if heart rate (HR) at clinical examination (HRex) was associated with HR during Holter monitoring and evaluated the reproducibility of Holter variables. Fifty clinically healthy, privately owned dogs of the breeds Cavalier King Charles Spaniel (CKCS), Wire-haired Dachshund (wD), or Cairn Terrier (CT). Prospective, longitudinal observational study. Dogs were recruited for clinical examination, echocardiography, and Holter monitoring. In 8 CKCS, Holter recordings were performed twice with a 7-day interval. Arrhythmia and heart rate variability (HRV) analysis (time and frequency domain analysis) were performed on Holter recordings. Fifteen out of 27 Holter derived variables were significantly associated with breed (P < .03), but not with age (P > .7), sex (P > .2), body weight (P > .7), degree of recording artifact (P > .4), or MVP (P > .6). During Holter recording, minimum (P = .0001) and mean HR (P = .0001) were higher in CKCS compared with wD. CKCS had significantly lower values than wD, CT, or both in 10 out of 13 HRV variables (P < .03). Minimum and mean HR during Holter recording were correlated with HRex (r = 0.55, P = .0003). HR and time domain variables had a coefficient of variation <10%. There is an influence of breed on Holter-derived variables in 3 breeds of small dogs. Arrhythmia and HRV analysis can be performed on 24-hour ambulatory ECG (Holter) recordings. Arrhythmia analysis includes HR measurements and identification of arrhythmias.

Arrhythmia and cardiac defects are a feature of spinal muscular atrophy model mice

Proximal spinal muscular atrophy (SMA) is the leading genetic cause of infant mortality. Traditionally, SMA has been described as a motor neuron disease; however, there is a growing body of evidence that arrhythmia and/or cardiomyopathy may present in SMA patients at an increased frequency. Here, we ask whether SMA model mice possess such phenotypes. We find SMA mice suffer from severe bradyarrhythmia characterized by progressive heart block and impaired ventricular depolarization. Echocardiography further confirms functional cardiac deficits in SMA mice. Additional investigations show evidence of both sympathetic innervation defects and dilated cardiomyopathy at late stages of disease. Based upon these data, we propose a model in which decreased sympathetic innervation causes autonomic imbalance. Such imbalance would be characterized by a relative increase in the level of vagal tone controlling heart rate, which is consistent with bradyarrhythmia and progressive heart block. Finally, treatment with the histone deacetylase inhibitor trichostatin A, a drug known to benefit phenotypes of SMA model mice, produces prolonged maturation of the SMA heartbeat and an increase in cardiac size. Treated mice maintain measures of motor function throughout extended survival though they ultimately reach death endpoints in association with a progression of bradyarrhythmia. These data represent the novel identification of cardiac arrhythmia as an early and progressive feature of murine SMA while providing several new, quantitative indices of mouse health. Together with clinical cases that report similar symptoms, this reveals a new area of investigation that will be important to address as we move SMA therapeutics towards clinical success.

Supraventricular Tachycardia in a Patient with Repaired Congenital Heart Disease.

This case illustrates the difficulty in diagnosing atrial tachycardia in a patient who had a Mustard procedure for transposition of great arteries. Identification of atrial arrhythmias, even when they occur at physiologic ventricular rates, is important, because these patients are at risk for thrombus development and symptoms related to periods of a more rapid ventricular response. Another potential concern is that if the heart rate is elevated moderately during an unrecognized arrhythmia, the patient may develop a tachycardia-mediated cardiomyopathy over time. Patients with repaired congenital heart disease who develop postoperative tachyarrhythmias usually are treated aggressively to restore sinus rhythm. This is especially true in those who have residual intracardiac lesions or depressed myocardial function.

HRV Analysis of Arrhythmias Using Linear - Nonlinear Parameters

Heart rate variability (HRV) refers to the beat-to-beat alterations in heart rate. HRV analysis is based on the concept that, fast fluctuations reflect the changes of sympathetic and vagal activity which results in variability of intervals between R waves i.e. “RR intervals”. In the current work HRV was assessed by traditional linear time and frequency-domain indexes, in parallel with the non linear Poincare plot analysis. Initially R peaks are detected from the ECG and RR interval signal is obtained which is further used to get the HRV signal. Spectral analysis of this HRV signal is done to estimate the power content in different frequency bands. Two frequency bands play a vital role in the power spectrum, a low frequency and a high frequency. Simultaneously, for time domain analysis, parameters such as mean of RR interval signal, standard deviation, coefficient of variance, root mean square of standard deviation are evaluated from RR interval signal and analyzed for different arrhythmias. Poincare plot analysis is an emerging quantitative-visual technique whereby the shape of the plot is categorized into functional classes that indicate the different arrhythmia. In this each R-R interval is plotted as a function of the previous one, and the standard deviations of the instantaneous and long-term R-R interval variability are calculated. It is observed that mean of RR interval signal and coefficient of variance plays an important role and can be used in classification along with the power content in low and high frequency bands. Also position and orientation of RR intervals in Poincare plot play an important role in visual identification of arrhythmias. The method is applied to normal sinus rhythm, ST change, CU Ventricular Tachyarrhythmia, Malignant ventricular arrhythmia signals. In this work, the different linear and non linear parameters evaluated show a particular range for various cardiac arrhythmias.

Cardiopulmonary exercise testing in congenital heart disease: (contra)indications and interpretation

Cardiopulmonary exercise testing (CPET) in paediatric cardiology differs in many aspects from the tests performed in adult cardiology. Children's cardiovascular responses during exercise testing present different characteristics, particularly oxygen uptake, heart rate and blood pressure response, which are essential in interpreting haemodynamic data. Diseases that are associated with myocardial ischaemia are rare in children. The main indications for CPET in children are evaluation of exercise capacity and the identification of exercise-induced arrhythmias. In this article we will review the main indications for CPET in children with congenital heart disease, the contraindications for exercise testing and the indications for terminating an exercise test. Moreover, we will address the interpretation of gas exchange data from CPET in children with congenital heart disease. (Neth Heart J 2009;17:385-92.).

Cardiopulmonary exercise testing in congenital heart disease: equipment and test protocols

Cardiopulmonary exercise testing (CPET) in paediatric cardiology differs in many aspects from the tests as performed in adult cardiology. Children's cardiovascular responses during exercise testing present different characteristics, particularly oxygen uptake, heart rate and blood pressure response, which are essential in interpreting haemodynamic data. Diseases that are associated with myocardial ischaemia are very rare in children. The main indications for CPET in children are evaluation of exercise capacity and the identification of exercise-induced arrhythmias. In this article we will review exercise equipment and test protocols for CPET in children with congenital heart disease. (Neth Heart J 2009;17:339-44.).

Technique of Open Ivor Lewis Esophagectomy

Technique of Open Ivor Lewis Esophagectomy

Effect of Prenatal Antiarrhythmic Treatment on Cardiac Function in a Twin Pregnancy

We present a case of supraventricular tachycardia affecting one fetus in a twin pregnancy. Before and after treatment with flecainide and cardioversion, we examined conduction times and heart rate variability (HRV) in both twins on the basis of magnetocardiography. Cardiac conduction times increased in both fetuses but HRV showed opposing effects with a number of HRV measures. This case demonstrates that magnetocardiography not only enables identification of fetal arrhythmia, but also permits the investigation of the effects of antiarrhythmic treatment on the conductive system as well as on interaction with the autonomic nervous system.

Straightforward waveforms

This is the 7th edition of a book with a practical, non-academic approach to the identification and treatment of cardiac arrhythmias.

Detection and analysis of fetal arrhythmia in a single twin fetus using magnetocardiography

Abstract An important clinical application of fetal magnetocardiography (FMCG) is the identification and classification of fetal arrhythmias. However, separation of fetal and maternal signals can be challenging due to cardiac conduction disturbances and changes in signal morphology. In twin pregnancy, the presence of an additional cardiac signal further complicates data processing. We report on the processing of FMCG signals obtained in twin pregnancy in the 28th week with arrhythmia in a single fetus. A 12-min FMCG was recorded using a 61-channel biomagnetometer with sufficient coverage to simultaneously register both fetal cardiac signals. Using signal template matching, digital averaging and subtracting techniques, the cardiac signals of the mother and both fetuses could be separately identified and displayed. Examination of the timing of ventricular complexes in combination with their signal morphologies permitted the identification and classification of arrhythmic events. Two episodes of supraventricular tachycardia over total period of 3 min at heart rates around 280 bpm were present. The remaining trace showed intermittent changes between sinus beats, supraventricular extrasystoles and compensatory pauses as well as blocked atrial beats. We conclude that appropriate signal processing techniques permits the clinical interpretation of FMCG signals even in complex spatio–temporal combinations of signals.

Holter electrocardiography in dogs showing doxorubicin-induced dilated cardiomyopathy

Early identification of arrhythmias in dogs showing doxorubicin-induced cardiomyopathy was studied. Ten healthy dogs were assigned to groups A (n=5) and B (n=5). Dogs from group B were given doxorubicin 30mg/m² intravenously, every 21 days, until a cumulative dose of 180mg/m² or 240mg/m² was reached. Dogs from group A (used as control) were administered saline intravenously at the same group B intervals. As soon as myocardium dysfunction was observed in dogs from group B, determined by a shortening fraction below 20%, increased E-point to septal separation above 0.7cm, and increased end-systolic left ventricular volume index (61.4ml/m²), a 24-hour Holter was recorded in all dogs from both groups. There was an increase of minimum heart rate (44.6%) and mean heart rate (41.7%) in animals from group B in comparison with the control animals. Either supraventricular or ventricular arrhythmias were observed, despite group B dogs showed higher occurrence of supraventricular arrhytmias. Holter monitoring is efficient in early determination of heart rate and cardiac rhythm alterations in dogs showing doxorubicin-induced myocardial dysfunction.

AB17-1: Direct voice communication and centralized telemetry monitoring/nursing process improvement shorten arrhythmia alarm response time

A centralized telemetry monitoring system (TMS) is employed to facilitate early identification of critical arrhythmias and acute medical decompensation. Appropriate intervention can only be effected if the abnormality is communicated rapidly and efficiently to the direct care giver.

Use of the electrocardiogram in acute myocardial infarction.

This review article describes the use of electrocardiograms in facilitating the clinical care of patients with acute myocardial infarction. Analysis of patterns of ST-segment elevation can help in making decisions about reperfusion therapy. Correct identification of arrhythmias and new conduction abnormalities is an important challenge.

Performance of an automated external cardioverter defibrillator for inhospital ventricular malignant arrhythmia

Purpose Ventricular fibrillation (VF) and ventricular tachycardia (VT) are the major underlying rhythm during in-hospital cardiac arrest. For a patient in VF/VT the probability of successful defibrillation and subsequent survival to hospital discharge is directly and negatively related to the time interval between onset of the arrhythmia and delivery of the first shock. The data about this interval in clinical practice is heterogeneous and inconclusive, however the literature estimates it to be about 60 seconds in monitored units. Continuos ECG monitoring allows identification of such arrhythmias and alert nursing and medical staff. The time delay between the arrhythmic event and human intervention is still a challenge for clinical practice.

An introduction to cardiac monitoring and rhythm interpretation

ABSTRACTThis article is the first in a series which will explore the identification and management of cardiac arrhythmias within the peri-operative care setting. To improve patient safety, the number of patients who are monitored within the recovery room is rising, whilst cardiac monitoring remains a fundamental requirement for patient care during the anaesthetic phase. Therefore, the role of the peri-operative care nurse requires an ability to interpret cardiac arrhythmias and to subsequently instigate the appropriate management.The purpose of this preliminary article is to establish the basic principles that underpin the identification and management of arrhythmias. Cardiac physiology is reviewed and then applied to the derivation of the waveforms of the normal ECG. The article continues with a summary of accurate electrode placement and some tips for troubleshooting in the presence of ‘artifact’. A systematic analysis tool, which can be easily applied to clinical practice, completes the article.

PITFALLS IN EXERCISE STRESS TESTING

Correct recognition of cardiac rhythm plays an essential role in determining when a stress test is terminated. More importantly, appropriate diagnosis determines the acute therapy in recovery. However, there are certain clinical cases that make determination of rhythms difficult. We examined this issue in 16 cases of ventricular tachycardia (VT), supraventricular tachycardia (SVT) or complete heart block (CHB) that were problematic and clinically affected the outcome of the exercise strees test (EST) and immediate therapy of the patient. There were 11 males, average age of 49 ± 31 years (range 27 – 80). Twelve had structural heart disease. The baseline electrocardiogram (ECG) was abnormal in 12. Indications for the EST were: angina-3, arrhythmia-8, exercise capacity-4, and post infaraction-1. The ESTs used were: Bruce, Modified Naughton and manual protocol-14, 15-watt ramping bike protocol-1 and Adenosine-1. The average heart rate pre-exercise was 69 ± 33 beats per minute (bpm). The baseline rhythm was sinus in 14 patients, with 1 patient in atrial fibrillation and 1 with advanced 2nd degree atrioventricular block. The arrhythmias recorded during the EST or recovery were nonsustained VT-5, sustained VT-5, SVT-5 and CHB-1. One idiopathic sustained VT (rate 216 bpm) required DC cardioversion. From these studies we determined the following: 1) SVT with abberant conduction in 2 patients was thought to be VT; 2) No patient with VT had a positive EST for ischemia despite 4 of 10 with the underlying diagnosis of coronary artery disease; 3) Sustained VT (average duration 41 seconds, rate 156 bpm) stopped spontaneously in 4 patients without producing hemodynamic deterioration and 4) One patient developed complete heart block and symptomatic chronotropic incompetence. We conclude from these studies that: 1) SVT with abberancy is frequently thought to be VT and affects EST termination; 2) Patients with sustained VT rarely have hemodynamic collapse if VT rate is slower; 3) Most exercise induced tachycrdias terminated spontaneously; 4) The EST rarely demonstrated ischemia with exercise induced nonsustained VT, possibly because of premature test termination; and 5) Most patients with VT did not have coronary artery disease. Acute management decisions affected 6 of 16 EST. Correct identification and interpretation of arrhythmias is important for proper test termination and acute management.

Wave recognition and use of the intraoperative unipolar esophageal electrocardiogram

Study Objectives: To evaluate the automated determination of onset and offset times and amplitudes of all the PQRST waves from simultaneously recorded surface electrocardiogram (SECG) and unipolar esophageal ECG (EsECG). The occurrence of ST segment deviation is also examined. Design: Prospective, observational study. Setting: University hospital. Patients: 30 patients undergoing coronary artery bypass graft (CABG) surgery. Interventions: SECG and two-lead unipolar EsECG were recorded after induction of anesthesia and before cardiopulmonary bypass (CPB). Measurements and Main Results: The amplitudes of the P and T waves and the ST segment deviation were measured. EsECG had more noise than SECG. Slight movement of the esophageal electrodes occasionally caused substantial changes in the wave amplitudes and ST segment deviation in the unipolar EsECG. The maximum P wave amplitude in EsECG was, on average, 97% greater than the maximum P wave amplitude in SECG. ST segment deviation in EsECG was observed in the absence of ST segment deviation in SECG and vice versa. Conclusions: The recognition and measurement of all the PQRST waves can be improved and automated by simultaneous use of EsECG and SECG. The P wave amplitude is greater in EsECG than in SECG, which may facilitate the identification of supraventricular versus ventricular arrhythmias. ST segment deviation in the unipolar EsECG may not be suitable for the routine detection of ischemia.

Automatic arrhythmia identification using analysis of the atrioventricular association. Application to a new generation of implantable defibrillators. Participating Centers of the Automatic Recognition of Arrhythmia Study Group.

Atrioventricular association is a key criterion for arrhythmia diagnosis. Its use in a defibrillator should significantly reduce the incidence of inappropriate shocks. Therefore, we evaluated the diagnostic accuracy of an algorithm that uses dual-chamber sensing and analysis of atrioventricular association to discriminate ventricular from supraventricular arrhythmias in a prototype of an implantable defibrillator. The algorithm performed a stepwise analysis of arrhythmias. The rhythm was first classified on the basis of cycle lengths. Each episode was then classified as supraventricular or ventricular in origin on the basis of the stability of cycle lengths and atrioventricular association. This algorithm was evaluated in 156 episodes of induced sustained tachycardias. Eighty-nine tachycardias were taken from the Ann Arbor electrogram library; the others were recorded in 50 patients during electrophysiological studies. The atrial and ventricular signals were stored on an external recorder and then injected into an external prototype of a defibrillator system. The algorithm correctly diagnosed 96% of ventricular tachycardia episodes, 100% of ventricular fibrillation episodes, and 92% of double-tachycardia episodes. The mean detection time for ventricular tachycardia was 2.6 +/- 0.8 seconds, and for ventricular fibrillation, it was 2.1 +/- 0.4 seconds. The positive predictive values for the diagnoses of atrial fibrillation and atrial flutter were 92% and 86%, respectively. For ventricular tachycardia and ventricular fibrillation, the values were 95% and 100%, respectively. Analysis of atrioventricular association promotes reliable differentiation between ventricular and supraventricular tachycardias and should enhance the diagnostic capabilities of implantable defibrillators.

Indications for Dual-Chamber (DDD) Pacing in Implantable Cardioverter-Defibrillator Patients

New technologic development of implantable cardioverter-defibrillators (ICDs) keeps up with the exponential increase of their use for primary and secondary prevention of sudden cardiac death. The first-generation ICD with limited shock capability alone could be considered adequate in most cardiac arrest victims, but it was not suitable for sudden death prevention in all high-risk patients with cardiac disease. The second-generation ICD was comprised of hybrid pacemaker-defibrillator systems that provided on-demand ventricular antibradycardia pacing. The third-generation devices include additional functions, such as antitachycardia pacing for ventricular tachycardia (VT) reversion and low-energy ventricular cardioversion, in addition to ventricular defibrillation and single-chamber ventricular demand pacing. In the near future, advanced dual-chamber atrioventricular (AV) pacing and defibrillating systems will also be available. The dual chamber ICD will allow atrial inhibited/dual-chamber (AAI/DDD) rate-responsive pacing, simultaneous atrial and ventricular sensing to optimize the arrhythmia identification, and ICD shock delivery in the proper arrhythmia-related chamber. Clinical benefits of these devices compared with their cost and complexity will require careful evaluation. (Am J Cardiol 1996;78(suppl 5A):116–118)

Current management of acute myocardial infarction

Acute myocardial infarction is a devastating cardiac clinical event, which is the result of progressive coronary arteriosclerosis. Coronary heart disease is a major health concern that accounts for a significant number of hospitalizations, health care expenditures, and deaths. Recent advancements in the nature and pathophysiology of progressive coronary disease and infarction have allowed us to curb the natural course of the disease, shorten hospital stays, and improve patient outcomes. Focused history taking and physical examination, with the assistance of the appropriate laboratory studies and an electrocardiogram, facilitate the rapid identification of a patient with myocardial infarction. Overall clinical results will be improved by minimizing the time from diagnosis to therapy. Several initial measures are readily available to the physician at the time of the patient's arrival in the hospital emergency room. Consideration regarding relief of pain, anticoagulation, and contraindications for thrombolytic therapy should accompany the initial evaluation. For patients in whom the diagnosis is in doubt, adjunctive confirmatory testing and imaging studies should be urgently sought. Elderly patients have a higher mortality rate from infarction, so an aggressive approach in this group of patients is warranted. Administration of thrombolytic therapy or primary angioplasty will be most efficacious in a majority of patients. The evolution of adjunctive medications will further improve efficacy and avoid reinfarction. Proper dosage and timing of adjunctive medications, along with dosage titration based on hemodynamic response, will facilitate the best possible results. Rapid restoration of flow down a suddenly occluded epicardial coronary vessel is the primary end point in therapy. With this in mind, there has been an increasing trend toward mechanical restoration of flow by means of primary angioplasty in centers where this technologic capability is available. Close attention to the patient's hemodynamic status along with rapid identification and therapy of periinfarction arrhythmias will help to avoid clinical complications. When peripheral perfusion is compromised, hemodynamic monitoring, inotropic medications, and mechanical assistance may become necessary. Subsequent severe pump failure is usually the result of a devastating mechanical complication. Patients with mechanical complications have a high associated event-related mortality rate. Urgent identification of the nature of the complication with the use of invasive and noninvasive imaging studies, mechanical and inotropic assistance, and emergency surgical correction may be lifesaving. Careful patient follow-up and medical therapy aimed at maintaining left ventricular geometry, reducing ischemia and related events, and attempting to retard the progression of arteriosclerosis with anti-ischemic agents and lipid-lowering therapy, as well as estrogen replacement in female patients, can reduce the incidence of subsequent events and prolong life. New insights into the interactions of macromolecules, medications, and hormones with the coronary endothelium and atherosclerotic plaque are helping to shape the evolution of appropriate therapy for myocardial infarction and coronary heart disease in general.