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Sertindole is a new limbic-selective antipsychotic agent which has recently received marketing authorization in several countries across Europe for the treatment of schizophrenia. The experience gained in around 2200 patients treated with sertindole in controlled clinical trials has enabled optimal targeting of sertindole to those patient groups who will benefit most and who are least likely to experience adverse effects. Ultimately, it is how a new medicinal product is used in clinical practice, how it performs in everyday life, and how the patient who takes it feels and functions that determine the real benefit/risk ratio of a new medicinal product. The European Post-marketing Observational Serdolect® project (EPOS) is a post-marketing, referenced, observational, cohort, safety study in the treatment of schizophrenic patients initiated earlier this year. It is planned to recruit over 12 000 patients in two cohorts in centres throughout Europe. The aims are to provide a full safety evaluation of sertindole under marketed conditions at the relevant clinical dosage, and further, to provide epidemiological data on schizophrenic patients receiving sertindole or other treatment under the usual clinical conditions in Europe. At the moment, the study is the only one of its kind to be undertaken in schizophrenia and will provide important new data for psychiatrists around the world.

OBJECTIVE—To show whether increased QT dispersion on admission predicts ventricular fibrillation after acute myocardial infarction, and to determine the nature of time related changes in QT dispersion. DESIGN—Prospective cohort study. SETTING—Coronary care units of three teaching hospitals in Newcastle-upon-Tyne over an eight month period. PATIENTS—All had acute myocardial infarction according to World Health Organization criteria. INTERVENTIONS—For all patients, QT dispersion (QTd) and Bazett rate corrected QTc dispersion (QTcd) were measured from a high quality 12 lead ECG recorded on admission at a paper speed of 50 mm/s. In a subset, serial ECGs were recorded regularly to show time related changes in QTcd following acute myocardial infarction. MAIN OUTCOME MEASURES—Occurrence of ventricular fibrillation within the first 24 hours after myocardial infarction. RESULTS—Data collected from 201 patients, 12 of whom (6%) developed ventricular fibrillation within 24 hours. Neither QTd nor QTcd differed between those developing ventricular fibrillation and those who did not: QTd mean (SD), 74 (24) ms (95% confidence interval (CI) 59 to 89) v 66 (24) ms (95% CI 62 to 70), respectively; QTcd, 86 (26) ms0.5 (95% CI 70 to 102) v 77 (29) ms0.5 (95% CI 72 to 82), respectively. Significant QTcd changes occurred early after myocardial infarction. CONCLUSIONS—Admission QTd and QTcd do not predict ventricular fibrillation after acute myocardial infarction. There are significant changes in QTcd with time, which may account for this measured lack of correlation. Keywords: acute myocardial infarction; arrhythmia; ventricular fibrillation; QT dispersion

Heart failure is the leading cause of death in patients after surgery for ventricular tachycardia. This study examines the effects of antiarrhythmic surgery on 4 parameters of left ventricular (LV) function. Global ejection fraction, segmental wall motion score, homogeneity of contraction, and diastolic function were measured in 32 patients by technetium-99m radionuclide ventriculography. Ejection fraction was measured from the left anterior oblique image. Wall motion score was assessed semiquantitatively for 11 LV segments from 3 projections. Homogeneity of contraction was expressed as the SD of the LV phase analysis curve during systole from the left anterior oblique image. Diastolic function was expressed in terms of peak and mean first time derivative of the action potential (dV/dt) of the LV function curve. Subgroup analyses were performed to distinguish the effects of aneurysmectomy, coronary artery bypass grafting, and changes in angiotensin converting enzyme inhibitor therapy. Mean systolic function improved after surgery (ejection fraction 22% vs 32%, p0001; wall motion score 20 vs 13, p0.0001; phase analysis 18 vs 12, p0.03). Mean diastolic function also improved (peak dV/dt 0.83 +/- 0.32 vs 1.49 +/- 0.39, p = 0.006; mean dV/dt 0.41 +/- 0.15 vs 0.76 +/- 0.27, p = 0.006). Improvements were not confined to those who had aneurysmectomy or coronary bypass grafting and were not explained by changes in vasodilator therapy. Thus, antiarrhythmic surgery does not inherently damage LV function. Significant improvements were observed in most patients. Failure to improve indicated a poor longer term prognosis.

Antiarrhythmic Drug Efficacy in Patients with an ICD. There are a number of novel ways in which implantable cardioverter defibrillator (ICD) endpoints can he used in clinical trials to evaluate antiarrhythmic drugs. The advances in ICD technology (storage, retrieval, and accurate interpretation of ICD electrograms) expand the potential to include the use of an ICD endpoint as a clinical surrogate for sudden death. The ICD also provides the necessary safety net to test new drugs. The frequent need for‘antiarrhythmic drugs in patients already fitted with an ICD (e.g., for atrial fibrillation) necessitates knowledge of the drugs' effect on defibrillator threshold. There are interpretative problems and challenges associated with all types of ICD trials. A particular difficult issue is the degree to which the results of data on antiarrhythmic drug efficacy and safety acquired in the context of an ICD endpoint trial might he extrapolated to patient populations in which the device is not used. These and other challenging issues are discussed, with the goal of enhancing the design and interpretation of clinical trials featuring ICD endpoints.

Current nomenclature for atrioventricular junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with antero-posterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, while the mouth of the coronary sinus is shown as being posterior. While this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and atrioventricular nodal re-entry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology, and the North American Society of Pacing and Electrophysiology. It proposes a new, anatomically sound, nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value as regards the description of the atrioventricular junctions, establishing the principles of this new nomenclature.

Background . In unselected patients, cardiac failure accounted for most deaths after antiarrhythmic operation (ER) for postinfarction ventricular tachycardia (VT). This study aimed to determine whether patients at low risk of this outcome could be predicted from a retrospective analysis of variables from 100 consecutive ER patients. Methods . Thirteen variables suggested by other researchers as predictive of outcome were analyzed. At the time of study, ER was the only therapy available for drug refractory VT. Results . Only emergency ER, wall motion score less than 3 and Killip classification were significantly related to death from cardiac failure. The lack of correlation between emergency ER and variables of ER timing, VT less than 24 hours of ER or VT type implies that the need for emergency ER is also related to ventricular dysfunction. Multivariate analysis identified a group at particularly low risk of death with a specificity of 95%. Conclusions . Patients at low risk of death after ER can be identified prospectively. In the implantable cardioverter defibrillator era, elective ER is best reserved for such patients. Emergency ER may still be justified in younger patients without comorbidity who will die of VT without it.

Atrial fibrillation, a commonly encountered arrhythmia, has in recent years, been the subject of increased interest and intensive clinical research. There is also increasing awareness that atrial fibrillation is a major cause of embolic events which in 75% of cases are complicated by cerebrovascular accidents[1,2]. Atrial fibrillation is often associated with heart disease but a significant proportion of patients (about 30%) have no detectable heart disease[3]. Symptoms, occasionally disabling, haemo-dynamic impairment and a decrease in life expectancy are among the untoward effects of atrial fibrillation, resulting in an important morbidity, mortality and an increased cost for the health care provider[4]. The Working Group of Arrhythmias of the European Society of Cardiology created a Study Group on Atrial Fibrillation in order to establish recommen-dations for the better management of this arrhythmia and to promote multicentre studies. The purpose of this paper is to briefly outline the state of our knowledge on the clinical presentation, the causes, the mechanisms and therapeutic approaches currently available and to propose recommendations for management. Although atrial flutter can coexist with atrial fibrillation, it is considered a different arrhythmia and will not be covered in the present paper.

All aspects of health care are under intense scrutiny, none more so than the competence of health care professionals to diagnose and manage disease. Correctly, patients expect those who minister to them to be competent and properly trained. Concepts of what constitutes a good and a bad doctor vary widely. Good may equate with sympathy, yet sympathy is no substitute for ability. The question of competence has received relatively scant attention but is now an important issue. Establishing competence requires setting standards and usually setting conditions for maintaining clinical acumen and ability. Such is laudable, particularly as it can bring about constructive retraining and can divert specific clinical problems to those best able to deal with them. Specific circumscribed procedures have been an obvious first target for criteria of competence. Such procedures are amenable to audit and are performed in sufficient numbers to establish average rates for success, failure, and efficiency. Standards of competence have been suggested for areas such as angioplasty and stenting.1 Cardiac electrophysiological procedures have also been examined and are similarly amenable to suggestions for levels of competence.2 3 Competence involves exposure to and performance of procedures but more importantly it should include an audit of complications and success. It is to be expected that those with the greatest exposure are likely to be those most competent although this relation is not necessarily so simple. Experience in dealing with complications or anticipating their occurrence plays a large part in the successful performance of many clinical procedures, cardiac electrophysiological ones included. Establishing and maintaining levels of competence in those performing procedures is very desirable. It identifies those who can be expected to offer safe modern care, and it helps to identify manpower needs for given disease situations. There are, however, problems with establishing strict guidelines for …

A consistent 12-lead electrocardiogram (ECG) morphology and characteristic frontal plane axis shift from sinus rhythm to ventricular tachycardia (VT) was demonstrated in 10 consecutive patients with idiopathic right ventricular outflow tract (RVOT) VT. All arrhythmias were successfully ablated on the septal side of the RVOT.

Atrial flutter is a relatively rare but nonetheless important arrhythmia. Its mechanism and anatomy have been defined as right atrial macroreentry. It responds to treatment with a variety of antiarrhythmic agents but, in general, drug efficacy for acute termination is low. The addition of pacing to drug therapy markedly improves the success rate for restoration of sinus rhythm. Useful antiarrhythmic agents include amiodarone, sotalol, disopyramide, flecainide, and propafenone, but definitive efficacy studies have not been performed. The risk of provoking 1:1 AV conduction and a marked increase in ventricular response rate is always present. AV nodal blocking drugs (digoxin and verapamil) probably offer protection from this unwanted effect, but the prevalence of 1:1 conduction and the efficacy of AV nodal blockade remain to be established. When drug management fails, there is a place for radiofrequency ablation. Little is known about the thromboembolic risk of atrial flutter. As a consequence, the role of prophylactic anticoagulation is uncertain. Current interest in atrial flutter will ensure that these and other clinical questions are answered in the near future.

There is increasing evidence that class III antiarrhythmic agents may be superior to class I agents for the long-term treatment of life-threatening ventricular tachyarrhythmias. This open study evaluated the acute electrophysiologic effects, antiarrhythmic efficacy, and safety of different doses of intravenous dofetilide, a new class III drug, in 50 patients with sustained monomorphic ventricular tachycardia inducible by programmed electrical stimulation who had previously been unsuccessfully treated with 0 to 7 (median 3) other drugs. Intravenous dofetilide was administered over 60 minutes at the following dose levels: 1.5, 3.0, 6.0, 9.0, and 15.0 micrograms/kg. Significant class III activity was apparent at doses of 3.0 to 15.0 micrograms/kg, as evidenced by dose-related prolongation of the QTc interval by 13.4% to 14.2%, ventricular effective refractory period by 7.9% to 20.6%, and ventricular functional refractory period by 7.3% to 25.0%. The corresponding mean +/- SD plasma dofetilide concentrations ranged from 1.45 +/- 0.52 to 6.48 +/- 1.31 ng/ml. There was no evidence of reverse use-dependence. At these electrophysiologically active dose levels, intravenous dofetilide suppressed (complete response) or slowed (partial response) inducible ventricular tachycardia in 17 of 41 patients (41%) compared with 0 of 9 patients receiving only 1.5 micrograms/kg. The response rate was fairly uniform among the groups receiving 3.0, 6.0, 9.0, and 15.0 micrograms/kg. Intravenous dofetilide was hemodynamically well tolerated. Torsades de pointes (which was self-limiting) developed in only 1 patient, who was allocated to receive 15.0 micrograms/kg. There were no other proarrhythmic episodes or serious adverse effects. Further evaluation of the therapeutic potential of dofetilide in the management of life-threatening ventricular arrhythmias is justified.

Fifty-two consecutive patients with nonischemic ventricular tachycardia (VT) were seen between 1985 and 1991. Twenty-two patients underwent surgery, while in the remaining 30, the VT was well controlled on medication. In the surgical group, arrhythmogenic right ventricular dysplasia (ARVD) was the cause of VT in 12 patients, cardiomyopathy (CM) in 6, posttetralogy of Fallot repair in 2, myocarditis in 1, and myocardial hamartoma in 1. The mean number of drugs tried and found ineffective was 5.5. There were three early deaths; 13 patients are symptom-free without taking any medication. In the medical group, the pathology associated with the VT was myocarditis in 2 patients, CM in 11, and ARVD in 2. In ten patients, VT appeared idiopathic, 1 was exercise-induced, 3 were catecholamine sensitive, and 1 presented with long QT syndrome. Beta blockers controlled the symptoms in 43% of the patients, amiodarone in 20%, and flecainide in 17%. The mortality was higher in the surgical group, but 95% of them are VT-free, compared with those on medical treatment (55%) over the last 8 years' follow-up. In conclusion, the nonischemic VT is a serious condition. Medical therapy is usually effective, but if it fails, VT surgery should be considered.

OBJECTIVE--To undertake a quantitative assessment of different automatic QT measurement techniques and investigate the influence of electrocardiogram filtering and algorithm parameters. DESIGN--Four methods for identifying the end of the T wave were compared: (1) threshold crossing of the T wave (TH); (2) threshold crossing of the differential of the T wave (DTH); (3) intercept of an isoelectric level and the maximum T wave slope (SI); and (4) intercept of an isoelectric level and the line passing through the peak and the point of maximum slope of the T wave (PSI). Automatic QT measurements were made by all techniques following different electrocardiogram filtering and, when appropriate, with four different isoelectric levels and with three different threshold levels. SUBJECTS--12 simultaneous standard electrocardiogram leads, containing at least two electrocardiogram complexes, were recorded from 25 healthy volunteers relaxing in a semirecumbent position. MAIN OUTCOME MEASURE--Mean and standard deviation of differences between reference and automatic QT measurements were compared for the four techniques. RESULTS--The mean automatic QT measurements varied by up to 62 ms, which was greater than has been found between manual measurements by experienced clinicians. Technique TH was particularly poor. The other techniques produced consistent results for most electrocardiogram filter, isoelectric level, and threshold level setting; but technique SI underestimated QT relative to the other techniques. CONCLUSION--Different QT measurement techniques produced results which were influenced, to varying degrees, by filtering and technique variables. This is relevant for the inter-comparison of studies using different techniques. Technique TH, a common approach, is not recommended.

Nothing in arrhythmia management should be taken for granted. Errors and mistakes over the last 30 years must now force reappraisal of the arrhythmia risks and the risk-benefits of their treatment. Supraventricular tachycardias have attracted great interest from electrophysiologists and the fundamental mechanisms of many are now well established. Surprisingly, however, very little is known of the long-term implications of supraventricular tachycardias in terms of quality and quantity of life. Not even for asymptomatic WPW syndrome is there consensus in this regard. The extent of our deficiencies in knowledge need to be appreciated and more must be done to understand the natural history of these events.

The aim of this study was to quantify electrocardiographic changes during the onset and early stages of ventricular fibrillation. Thirty recordings of ventricular fibrillation (mean duration 57 s, range 24–160 s) were obtained from 23. Coronary Care Unit patients. Each recording was investigated using frequency analysis on 1 s epochs of data. A significant rise in the mean dominant frequency of ventricular fibrillation from 3·9 Hz (SD 0·8 Hz) to 5·9 Hz (SD 1·0 Hz) was observed between 1 s and 30 s ( P

Most of the current generation of senior clinicians have been trained to put the interests and needs of the patient first. The doctor-patient relationship is sacrosanct, a binding contract to strive f

Dilated cardiomyopathy is a global myocardial abnormality in which it is likely that there are relatively homogeneous electrical conditions. The pattern of arrhythmic complications, especially atrial ectopic beats, ventricular ectopic beats and the brief salvoes of polymorphic ventricular tachycardia which are characteristic of the condition, suggest that triggered automaticity is a more likely arrhythmia mechanism than reentry. Although treatment with 'conventional' antiarrhythmic agents has an important place, drugs which alter myocardial loading conditions (and thus, thereby, a possible mechanism of triggered automaticity) may be effective. Therapeutic strategies directed against the basic disease processes are in an early stage of clinical development but they hold great promise for the future.

Four ventricular fibrillation (VF) detection techniques were assessed using recordings of VF to evaluate sensitivity and VF-like recordings to evaluate specificity. The recordings were obtained from Coronary Care Unit patients. The techniques were: threshold crossing intervals (TCI); peaks in the autocorrelation function (ACF); signal content outside the mean frequency (VF-filter); and signal spectrum shape (spectrum). Using 70 extracts, each 4 s long, from VF recordings, the VF filter achieved a sensitivity of 77 per cent; the ACF, TCI and spectrum algorithms had sensitivities of 67, 53 and 46 per cent, respectively. Susceptibility to false alarms was assessed using 40 extracts from VF-like recordings. The TCI algorithm was the most specific (93 per cent), while the spectrum, VF filter and ACF algorithms had specificities of 72, 55 and 38 per cent, respectively. The TCI algorithm achieved overall sensitivity of 93 per cent and specificity of 60 per cent. The spectrum, VF filter and ACF algorithms had overall sensitivities of 80, 93 and 87 per cent, and overall specificities of 60, 20 and 0 per cent, respectively.

A review was undertaken of late post-infarct ventricular tachycardia in a district hospital cardiac care unit in order to study the clinical course of a total population of such patients from initial presentation to ultimate outcome. Thirty-six patients with this diagnosis were identified over a 312-yr period. Twelve were treated by empirically chosen antiarrhythmic drugs. Twenty-four were referred for electrophysiologically guided treatment, of whom 16 were treated by antiarrhythmic drugs, 3 by anti-ischaemic measures alone, and 5 by non-pharmacological antiarrhythmic treatments (antiarrhythmic surgery, percutaneous ablation, defibrillator implantation, cardiac transplantation). Of those treated empirically, 4 died in hospital of their arrhythmia, 1 died suddenly at home, and 2 suffered non-fatal arrhythmia recurrences during mean follow-up of 20 months. There were no arrhythmic deaths in those whose treatment was guided by serial electrophysiology studies, although 4 patients died of cardiac failure or reinfarction, and 3 were hospitalised with a recurrence of ventricular tachycardia during mean follow-up of 16 months. Age, concomitant medical problems and the apparent response to initial antiarrhythmic therapy were the main factors influencing management decisions. The apparent superiority of more intensive management strategies based on electrophysiology studies must be interpreted in the context of the selection processes applied to the total population initially presenting.

The results of surgery for postischemic drug-resistant ventricular arrhythmias (VA) are still controversial. The operative mortality in the literature ranges between 10% and 40% because of selection of patients. The authors reviewed their experience at Freeman Hospital where all patients with drug-refractory ventricular tachycardia (VT) or ventricular fibrillation (VF) underwent surgical treatment regardless of left ventricular function (LVF) and of time from infarction and operation. Between March, 1981, and March, 1988, 65 patients [53 men, 12 women aged thirteen to seventy-five years (mean fifty-four)] underwent surgery. All of them had a previous myocardial infarct (MI). Mean preoperative ejection fraction was 28% ± 11, and 32 % had single-vessel, 44 % double-vessel, and 24% triple-vessel disease. In 16 surgical treatment was undertaken on an emergency basis. All had intraoperative mapping based on activation sequence or, when this was not possible (noninducible VT/VF), on analysis of fragmented potentials. LV endocardial resection was performed in 64 patients. Heart transplant (HTx) was necessary in 1. Associated procedures were aneurysmectomy in 40 patients (62%), multiple cryoablation in 13 (20%), encircling ventriculotomy in 8 (12%), right ventricular endocardial resection in 1, coronary artery bypass grafting in 43 (66%), mitral valve replacement in 5 (8%), and closure of postinfarct ventricular septal defect (VSD) in 2. The operative mortality was 26% (17 patients}. The main cause of death was left ventricular failure, 13 (20%). The mortality was higher in patients with previous anterior MI 15/49 (31%) and in emergency operations 9/16 (56%). The follow-up ranged between four and forty months (mean twenty-two months) with 6 late deaths (2 arrhythmia related). In 11 patients (17%) postoperative arrhythmic episodes were observed, but only in 6 (5 drug controlled, 1 without therapy) was there recurrence of preoperative arrhythmia. Surgery for life-threatening VA allows good long-term results for relief of arrhythmias. Perioperative mortality is still high in unselected patients; it depends mainly on the preoperative LVF. HTx in cases with very depressed LVF is an option, but in the majority of patients in this group it was contraindicated.

Recainam is a new antiarrhythmic agent with class Ic properties. To evaluate its electrophysiologic effects and antiarrhythmic efficacy in patients with recurrent supraventricular tachycardia (SVT), programmed electrical stimulation was performed in 10 patients before and after intravenous recainam (loading dose 0.8 mg/kg, infusion 1 mg/kg/h), and in four patients on oral recainam 1,200 mg/day. Five patients had atrioventricular (AV) node reentrant tachycardia; five had AV-reciprocating tachycardia. There were no significant changes in electrocardiographic and intracardiac intervals after either intravenous or oral recainam. After intravenous recainam, the ventricular effective refractory period (ERP) shortened (231 +/- 14-219 +/- 9 ms, p less than 0.05). The antegrade ERP of all three bidirectional accessory pathway markedly prolonged, but the effect on retrograde accessory pathway and AV node ERPs was unremarkable. SVT induction was prevented in three of 10 patients and SVT cycle length increased modestly in seven (357 +/- 44-374 +/- 42 ms, p = 0.07). On oral recainam, an increase in the frequency of spontaneous SVT occurred in two patients. At the doses given, recainam caused less electrophysiologic change than expected, had modest antiarrhythmic efficacy, and might have significant arrhythmogenic potential.

Fascicular tachycardia in young patients without overt heart disease constitutes a rare but electrophysiologically distinct arrhythmia entity. Microreentry within the left posterior fascicle has been proposed as its mechanism, but evidence for this is inconclusive. This report details a patient with incessant fascicular tachycardia. The electrophysiological features, in particular the pattern of resetting response, provided strong evidence for reentry as the tachycardia mechanism. Satisfactory long-term arrhythmia control was achieved with flecainide.

Four cases of familial ventricular tachycardia are presented. In each family the proband was an adolescent girl. Twelve members in the four families were affected and all were female. The clinical and electrocardiographic features were relatively constant within each family but there were striking differences between families. These differences argue against a common electrophysiological or pathophysiological basis for the ventricular tachycardia.

Diuretics and angiotensin-converting enzyme inhibitors currently are the mainstay of both acute and chronic heart failure management. They have earned their place by bringing measurable and reliable clinical benefit to patients with all grades and types of heart failure. Other treatments--digoxin, vasodilators and inotropes--offer less secure efficacy and their clinical role is at times controversial. The need for new remedies is inescapable. Despite current therapy, heart failure causes a distressing reduction in both quality and quantity of life. As knowledge of the pathophysiology of heart failure is gained, more selective treatment options may become available offering hitherto unknown specificity but demanding remarkable levels of diagnostic accuracy.

Surface electrocardiogram (ECG) signals on approximately orthogonal leads were recorded during six episodes of ventricular fibrillation (VF) provoked during electrophysiology studies. The aim was to examine the utility of frequency analysis for investigating recordings of VF made on three ECG leads. Successive 2.048-s data epochs were transformed into the frequency domain using a fast Fourier transform (FFT) algorithm. A similar and characteristic amplitude spectrum was observed on all ECG leads in all VF recordings. Coordination of separate ECG leads was assessed by determining the relative phases of frequency components at 4.39, 5.37, and 6.34 Hz. During four VF recordings these phase differences were variable but showed some periods of stability. During two VF recordings the phase differences at 5.37 Hz remained almost constant throughout the event. This study suggests that a degree of myocardial electrical organization exists during VF and is reflected in the surface ECG. >

The mechanism of human ventricular fibrillation (VF) remains elusive. This study compared the spectra of electrograms and surface ECG signals recorded during human VF. Six episodes of VF were recorded during electrophysiology studies. ECG signals were recorded from leads I, aVF and V2, and a bipolar electrogram recorded from the right ventricular apex (RVA). The RVA signal was rectified and low pass filtered. The first 10 s of each VF was separated into ten 1 s epochs. The spectrum of each epoch was estimated with an FFT algorithm and the frequency of the dominant peak (DomF) calculated. Mean (SD) DomF increased from 4.25 (1.00) Hz at 1 s to 5.65 (0.92) Hz at 10 s in the ECG recordings and 4.72 (0.91) Hz at 1 s to 6.55 (1.53) Hz in the RVA recordings. In 40% of the epochs included in this study, a similar value of DomF was seen in all three ECG leads and the RVA lead. This study shows a degree of similarity between surface ECG and intracardiac signals during the early stages of human VF.

Automatic QT interval measurement methods of T wave end determination include: the threshold crossing point of (a) the T wave and (b) the differential of the T wave and (c) the intercept of the isoelectric level and the maximum T wave slope. The aim of this study was to assess the effects of ECG filtering and threshold and isoelectric levels on these techniques using thirty 12 lead ECGs with a range of T wave morphologies. Low pass filtering (40 Hz vs. 100 Hz) resulted in the following changes in QT measurement relative to manual reference values: a -1 ms, b +34 ms, c -19 ms. Increasing high pass filtering (0.05 to 0.5 Hz) decreased the mean value for all techniques. Reducing threshold levels increased mean values by 14 ms (a) and 8 ms (b). The choice of isoelectric level had little effect on c while a increased by 15 ms. Filtering and parameter choice influence automatic QT measurement techniques and their effects need to be considered when comparing results. >

Self-terminating ventricular fibrillation (VF) is unusual and poorly characterized. The aims of this study were firstly to compared the ECG spectral features of sustained and self-terminating VT, and secondly to identify and features which precede self-termination. Twenty recordings of self-terminating VT (mean duration 10.7 s range 6-50 s) and thirty recordings of sustained VF (mean duration 57 s, range 24-160 s) were obtained from Coronary Care Unit patients. The spectra of a 1 s epochs was estimated using the VF algorithm. The center frequency and size of the dominant spectral peak was calculated for each 1 s epoch. At the onset of both sustained and self-terminating VF, both peak size and dominant frequency increases significantly. Self-termination was preceded by a decrease in both dominant frequency and peak size. The study shows that substained and self-terminating VF share similar ECG features at onset, and that self-terminating is preceded by a slowing down of the arrhythmia. >

Forty five recordings of ventricular fibrillation (VF) are analyzed and the changes in frequency spectrum accompanying the transition to VF are investigated. A rapid increase in signal power was observed in the 4-8-Hz band at the start of VF, rising to 75% in an average of 9.0 s for self-terminating VF (N=5), 5.8 s for recordings where VF was preceded by ventricular tachycardia (VT) (N=7), and 4.6 s for the remainder of VF records. (N=33). These findings have implications for VF detection. It is concluded that, during the onset of VF, a high proportion of signal power is concentrated in a relatively small frequency band; the maximum contribution to this band peaks early after the onset of VF. >

This study examined whether time-frequency analysis can reveal dynamic characteristics of human ventricular tachyarrhythmias. The authors investigated 11 episodes of self-terminating polymorphic ventricular tachycardia (PVT) recorded from 7 patients during routine electrophysiology studies. The mean duration was 7.3 s (range 3.7-15.6 s). Surface ECG leads I, aVF and VI were recorded, as well as a bipolar electrogram from the right ventricular apex (RVA). The time frequency distribution (TFD) was obtained using a smoothed Wigner distribution algorithm with a time resolution of 20 ms and a frequency resolution of 0.488 Hz. An identical dominant frequency was recorded on all 3 ECG leads 34.5% of the time. There was a significant correlation between the reciprocal of DomF obtained from the RVA signal, and the W interval (r=0.82, mean difference 0.2 ms SD 24.1 ms). In 8 of the 11 PVT recordings, DomF fell and W interval increased prior to termination. This study has shown that time frequency analysis is a valuable tool for investigating human tachyarrhythmias.

There are currently two different surgical approaches to the abnormal pathway, Wolff-Parkinson-White (WPW) syndrome-the endocardial (ENDO) and epicardial (EPI) techniques. In recent years, ablation of accessory pathways can be achieved by catheter-induced radiofrequency (RF) current. This study was undertaken to assess our results of surgical treatment for WPW syndrome in the current era of catheter ablation. From 1985 to 1993, 51 patients (33 male and 18 female) with WPW syndrome underwent operations for ablation of accessory pathways. Associated anomalies included Ebstein's anomaly, coronary artery disease, and tricuspid atresia. Preoperatively, 6 patients underwent unsuccessful RF catheter ablation. Fifteen (29%) patients were operated with the ENDO technique and 36 (71%) with the EPI technique. There was no early death in either group. In the immediate postoperative period 40 (78%) patients were in sinus rhythm. The electrophysiological studies revealed successful ablation of the pathway in 50 (98%) patients. On complete late follow-up (mean, 36 months) all patients were back to preoperative levels of activity. Our experience indicates that excellent results can be achieved with each of these two techniques. The left free wall accessory pathways may be ablated in a more reproducible way with the ENDO approach. The concept that surgical ablation of accessory pathways may prevent further atrial fibrillation is supported by the low incidence in this series. Operations for WPW syndrome may become indicated for RF ablation failure, when additional procedures are required. In these cases the surgical skill should be available, and this is a skill that should not be lost.

A 14-year-old girl with right ventricular dysplasia and recurrent drug refractory ventricular tachycardia underwent thoracoscopic mapping cryoablation. Good access to the right ventricular free wall was obtained. We suggest this technique may have an important role in the management of patients with right ventricular tachycardia.

OBJECTIVE—To report outcome following surgery for postinfarction ventricular tachycardia undertaken in patients before the use of implantable defibrillators. DESIGN—A retrospective review, with uniform patient selection criteria and surgical and mapping strategy throughout. Complete follow up. Long term death notification by OPCS (Office of Population Censuses and Statistics) registration. SETTING—Tertiary referral centre for arrhythmia management. PATIENTS—100 consecutive postinfarction patients who underwent map guided endocardial resection at this hospital in the period 1981-91 for drug refractory ventricular tachyarrhythmias. RESULTS—Emergency surgery was required for intractable arrhythmias in 28 patients, and 32 had surgery within eight weeks of infarction ("early"). Surgery comprised endocardial resections in all, aneurysmectomy in 57, cryoablations in 26, and antiarrhythmic ventriculotomies in 11. Twenty five patients died

Abstract —Current nomenclature for the atrioventricular (AV) junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with antero-posterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, although the mouth of the coronary sinus is shown as being posterior. Although this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and atrioventricular nodal reentry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. It proposes a new anatomically sound nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value for description of the AV junctions, establishing the principles of this new nomenclature.

OBJECTIVE: To compare manual and computer automated techniques for measuring QT dispersion. DESIGN: Assessment of the ability of manual and automatic measurements of QT dispersion to discriminate between a normal group and two cardiac groups. SUBJECTS: 12 simultaneous electrocardiogram leads were recorded from 25 healthy volunteers, 25 subjects after myocardial infarction, and 25 with cardiac arrhythmias. MAIN OUTCOME MEASURES: For each subject, QT dispersion was measured as the difference between the maximum and minimum QT from all 12 leads and separately for only those leads with T amplitudes of > 100 microV and for those > 250 microV. RESULTS: Manual QT dispersion (T > 100 microV) was greater (P < 0.02) in the arrhythmia patients (mean (SD), 45 (21) ms), but not the infarction patients (54 (36) ms), than in the normal subjects (39 (13) ms). There were no significant differences when all T waves were included. QT dispersion was significantly reduced by an average of 30% when T waves < 100 microV were excluded, and by 51% when those < 250 microV were excluded. Automatic techniques gave different measurements for dispersion in comparison with manual measurements. Three of the four automatic techniques detected significant differences between normal and both patient groups when no leads were excluded (P < 0.01) as well as when T waves < 100 microV were excluded (with increased significance, P < 0.002). CONCLUSIONS: Measurements of QT dispersion from small T waves increases measurement variability and reduces the potential for detecting clinical differences. Automatic measurement of QT dispersion gives different results from manual measurement, but can satisfactorily discriminate between normal and abnormal groups with good quality electrocardiograms.

Arrhythmogenic right ventricular disease may be associated with life-threatening and drug refractory ventricular arrhythmias. Right ventricular disarticulation procedures are effective antiarrhythmic surgical approaches in selected patients. This study examined the role of late potentials in the postoperative development of new ventricular arrhythmias, and showed that right ventricular isolation is effective, probably because it destroys the tissue giving rise to late potentials. Total disarticulation is associated with fewer postoperative arrhythmias than partial isolation procedures. Total disarticulation may be the surgical approach of choice in such patients.

Ventricular fibrillation (VF) is a potentially lethal disorder of heart rhythm. One persistent feature seen during VF is a prominent peak in the ECG spectrum between 3 and 7 Hz. The frequency of this peak generally increases during the first few seconds, and may also change abruptly during the arrhythmia. The presence of such a peak in the ECG spectrum indicates that the underlying electrical activity in the heart is periodic, the dynamics of this periodic activity may well be important in understanding the electrical mechanisms of VF. An example of the changes in spectra obtained using conventional techniques is shown in a figure. However, conventional frequency analysis techniques are inappropriate for use with nonstationary signals. The aim of this project was therefore to assess the suitability of the time-frequency distribution for identifying dynamic changes in periodic activity during VF.

OBJECTIVE: To assess differences in the accuracy of automatic QT measurement in three subject groups, and to determine the influence of T wave amplitude on these measurements. SUBJECTS: Standard simultaneous 12 lead electrocardiograms were acquired from 25 patients post myocardial infarction, 25 with arrhythmias, and 25 controls. DESIGN: Because there is not yet a standard automatic method for QT analysis, four different techniques were used. Manual QT measurements were used as the reference. QT was measured in two complexes by each technique in each lead, subject, and group. MAIN OUTCOME MEASURE: The differences between reference and automatic QT measurements from the three subject groups were compared independently for the four techniques. The T wave amplitudes for each of the groups were also compared. RESULTS: Variability of the automatic QT measurements, relative to the manual reference, in the cardiac patients was 2.1 times that in the controls (P < 0.005). Mean T wave amplitude was lower (by a factor of two) for the cardiac patients compared with the controls (P < 0.01). No simple relation between T wave amplitude and the difference between automatic and manual QT measurements was found, although the difference was 2.2 times greater for absolute T wave amplitudes of less than 0.25 mV (P < 0.001). CONCLUSIONS: Automatic QT measurement techniques are less accurate in cardiac patients than in controls. Measurements from T waves with amplitudes less than 0.25 mV are less reliable.

Supraventricular tachycardias (SVTs) are common and are widely regarded as a nuisance. They are often repetitive and persistent, and cause more upset than is currently acknowledged although only rarely do they threaten life. Surprisingly, they are ill-defined. A modern approach to SVT requires an accurate diagnosis and a readiness to abandon obsolete therapies in favour of effective new strategies, whether pharmacological or ablative.

Electrical Organization During VF. Introduction: Ventricular fibrillation is a most dangerous cardiac arrhythmia that has received considerable attention, yet its pattern of electrical activation remains controversial. The aim of this study was to investigate the degree of organization during the clinical arrhythmia and to examine the phase relationship between deflections in independent ECG leads. Methods and Results: Ten recordings of ventricular fibrillation were examined. Each had been provoked during routine electrophysiological study. The mean duration of ventricular fibrillation was 21 seconds (range 11 to 34). Independent and approximately orthogonal ECG leads I, aVF, and V2 were recorded to computer at a sampling rate of 250 Hz. The phase relationship of each ECG lead pair was measured from the lag of peaks in their cross-correlation function (CCF). In 61% of The 1-second ECG epochs analyzed, CCF peak lag changed by < 20 msec compared to The previous epoch. Thus, the overall phase relationship was stable most of the time. Changes in CCF peak lag tended to be either gradual or to punctuate periods of stability. Conclusions: This study provides evidence of organized myocardial activation during human ventricular fibrillation.

The aim of this study was to quantify the electrocardiographic signal characteristics of three types of ventricular arrhythmia; monomorphic ventricular tachycardia, polymorphic ventricular tachycardia and ventricular fibrillation. Patients in a coronary care unit were monitored using a single bipolar ECG lead. Thirty episodes of ventricular tachyarrhythmia (ten from each group) were recorded automatically by computer. Frequency analysis of ten consecutive 1 s epochs from each recording gave 100 spectra for each tachyarrhythmia group. Each spectrum was characterised by the frequency, width and proportional size of the dominant peak. Despite a qualitative similarity in spectral appearance, there were significant differrences in all characteristics between the tachyarrhythmia groups ( P

The aim of this study was to quantify changes in the spectrum of the electrocardiogram during the onset and early stages of ventricular fibrillation. The authors have only examined the surface electrocardiogram in a single lead, hence it is possible only to speculate on the electrical activity in the heart giving rise to these surface features. Nevertheless, these findings with others (Ideker et al., 1981; Davidenko et al., 1992; Clayton et al., 1994) suggest that the electrical activity in the heart during ventricular fibrillation is coherent and indicate that a reappraisal of this arrhythmia is needed. Signal processing techniques have been widely used in electrocardiography for signal conditioning and arrhythmia recognition. This study has shown that this approach can be used to investigate the signal characteristics of an arrhythmia, and that these characteristics when quantified can provide clinically relevant information.