Improvement in Atrial Fibrillation-Related Symptoms After Cardioversion: Role of NYHA Functional Class and Maintenance of Sinus Rhythm

Background

The European Heart Rhythm Association (EHRA) score is a proven and validated tool for assessing the symptoms of atrial fibrillation (AF). Little is known about the variables related to this score and how it changes after cardioversion.

Methods

We analyzed 744 patients undergoing elective cardioversion in whom AF-related symptoms were assessed at baseline and after 6 months of follow-up using the EHRA score. We assessed the association between the EHRA score and other clinical and echocardiographic variables at baseline and after 6 months of follow-up.

Results

At 6 months of follow-up, we observed a reduction in the EHRA score in 50% and worsening in 2.8% of patients who remained in sinus rhythm (SR) compared with 34.6% and 11.3%, respectively, of patients with AF episodes (p<0.0001). Patients who maintained SR at 6 months were less symptomatic than those with AF (EHRA score 1.13 ± 0.35 vs 1.42 ± 0.59; p<0.0001). The independent predictors for reduction in the EHRA score after cardioversion were NYHA ≥II at baseline and maintenance of SR (p<0.0001).

Conclusion

The greatest improvement in AF-related symptoms was in patients who remained in SR at 6 months after cardioversion and in patients with worse NYHA functional class at baseline.

Spontaneous cardiac resynchronization

A 73-year-old woman with dilated cardiomyopathy presented with heart failure. The ECG showed sinus rhythm with left bundle branch block, left-axis deviation and prolonged QRS duration and frequent ventricular premature complexes from the left ventricular septal wall were present. Ventricular premature beats had narrower QRS duration than sinus node beats conducted through the His-purkinje fibers consistent with resynchronizing beats. The mechanisms of narrowing of the QRS complex produced by premature beats in cases of impaired intra and interventricular conduction are discussed.

Efficacy and safety of d,l-sotalol in patients with ventricular tachycardia and in survivors of cardiac arrest

OBJECTIVE

The aim of this study was to assess the antiarrhythmic efficacy and safety of d,l-sotalol in patients with ventricular tachycardia (VT) or ventricular fibrillation (VF) and in survivors of cardiac arrest and to identify the factors that are associated with arrhythmia suppression and therefore might be helpful in predicting drug efficacy.

BACKGROUND

Despite increasing use of the class III antiarrhythmic agent d,l-sotalol, data on its short- and long-term efficacy in a large patient cohort are lacking. Information on its long-term tolerability and safety is limited.

METHODS

A total of 396 patients with inducible sustained VT or VF (VT/VF) underwent programmed stimulation before and after receiving oral d,l-sotalol (240 to 640 mg/day). Patients in whom VT/VF was rendered either noninducible or more difficult to induce (more extrastimuli or faster drive cycle length needed for VT/VF induction) were discharged on a regimen of oral d,l-sotalol.

RESULTS

d,l-Sotalol suppressed VT/VF in 151 patients (38.1%) and rendered the arrhythmia more difficult to induce in 76 patients (19.2%). The extent of drug-induced prolongation of right ventricular refractoriness and a shorter VT cycle length at baseline were independent predictors of immediate drug efficacy. Torsade de pointes developed in seven patients (1.8%). Two hundred ten patients (53%) continued to receive d,l-sotalol and were followed up for 34 +/- 18 months (mean +/- SD). The actuarial rates for the absence of arrhythmic recurrence (either VT/VF or sudden death) at 1 and 3 years were 89% and 77%, respectively. Actuarial rates for overall survival at 1 and 3 years were 94% and 86%, respectively. VT/VF suppression by d,l-sotalol was an independent discriminant variable that separated patients with and without arrhythmia recurrence. However, noninducibility of VT/VF did not predict freedom from sudden death.

CONCLUSION

Oral d,l-sotalol is effective and safe in patients with VT/VF. However, sudden cardiac death develops in a significant proportion of patients, and programmed stimulation seems to be of limited value for its prediction.

Reduced beat-to-beat changes of heart rate: an important risk factor after acute myocardial infarction

The prognostic significance of heart rate variability derived from 24-hour electrocardiographic recordings was investigated in 250 patients with acute myocardial infarction. During a follow-up of 6 months 15 patients experienced a serious arrhythmic event. These patients showed a significantly reduced beat to beat variability (p = 0.006), a slightly reduced 5-min variability (p = 0.04) and no significant differences in the 24-hour variability compared to the patients free of arrhythmic events. Based on Cox proportional hazard analysis, beat to beat variability remained an independent risk factor (p = 0.0036) in addition to the presence or absence of ventricular late potentials (p = 0.0004) and history of previous infarction (p = 0.04).

[In vitro validation of intravascular ultrasound, computerized and magnetic resonance tomography in diagnosis of atherosclerotic vascular segments in comparison with direct magnification radiography]

The depiction of atherosclerotic vessel abnormalities is a prerequisite for percutaneous interventional therapy and long-term observations of peripheral artery disease. The aim of this in-vitro study was to determine the potentials and limitations of 12.5 and 20 MHz intravascular ultrasound, computed tomography and magnetic resonance (MR) imaging in comparison to direct magnification radiography for the localization and quantification of peripheral vessel wall calcifications. Forty-three postmortem, human iliac segments were examined by intravascular ultrasound (12.5 and 20 MHz), computed tomography and magnetic resonance tomography (gradient echo-and spin echo-technique). For comparative analysis, each segment was divided into eight sectors of 45 degrees each; using all five methods, the presence of calcified wall areas was examined in each sector, and luminal area (42 segments) and plaque area (32 isolated plaques) were quantitatively estimated. In the sonograms, the circumferential extension of the boundary between intima and media was measured. 122 of 344 sectors showed regional vessel wall calcifications. Sensitivity of 20 MHz intravascular ultrasound was 73% versus 59% with the 12.5 probe, specificity was 97% with 20 MHz, 96% with 12.5 MHz. Sensitivity of both 12.5 and 20 MHz intravascular ultrasound was higher with increased thickness of the calcified structures. 20 MHz ultrasound identified the intima-media boundary averaging 146.8 degrees of the vessel circumference; the corresponding value of 131.8 degree with 12.5 MHz did not differ significantly. Computed tomography detected calcifications with a sensitivity of 88%, specificity was 88%. With MR imaging, sensitivity of the gradient echo-technique was 94% versus a sensitivity of 86% with spin echo-technique. Quantification of luminal and plaque areas showed that luminal area was precisely estimated only by 20 MHz ultrasound (no significant difference to direct magnification radiography), whereas all other techniques showed significant overestimation. Plaque areas were markedly overestimated by computed tomography and MR imaging, too. In an in vitro set-up, intravascular ultrasound, MR tomography and computed tomography do not allow an authentic depiction of peripheral vessel wall architecture. Limited resolution, subintimal shadowing and and distortion are the main limitations of these new techniques so that details of regional vessel wall calcifications cannot be presented thoroughly. Relevant over-estimation of luminal and plaque areas must be considered.

Comparison and combination of late potentials and spectral turbulence analysis to predict arrhythmic events after myocardial infarction in the Post-Infarction Late Potential (PILP) Study

Ventricular late potentials detected at the end of the QRS complex by the signal-averaged ECG have been shown to predict arrhythmic events after acute myocardial infarction. Spectral turbulence analysis is a novel technique for detecting abnormalities of cardiac electric activation inside the QRS complex. The purpose of this study was to combine these two analysis methods in order to increase the predictive power of the signal-averaged ECG in post-infarction patients. The study comprised a prospective series of 778 males under 66 years of age who survived the acute phase of myocardial infarction. Signal-averaged ECG recordings were performed before hospital discharge 2 to 3 weeks after infarction. The original Simson method was used for recording and analysing the time-domain signal-averaged ECG. Spectral turbulence analysis was performed using the same averaged vector magnitude QRS complexes (Del Mar Avionics). During the follow-up period of 6 months, 33 patients (4.2%) had an arrhythmic event (sustained monomorphic ventricular tachycardia in 13 cases, ventricular fibrillation in eight cases and sudden cardiac death in 12 cases). The predictive power of late potentials in the time domain, spectral turbulence analysis and their combinations were tested together with clinical variables using the Cox regression method.(ABSTRACT TRUNCATED AT 250 WORDS)

Are there gender differences in patients with coronary artery disease presenting with spontaneous sustained ventricular tachycardia and ventricular fibrillation?

The incidence of coronary artery disease (CAD) is greater in men than in women. The aim of the study was to analyze whether any gender-related differences in patients with CAD and documented spontaneous sustained ventricular tachyarrhythmias exist, and which parameters influence the induction of sustained ventricular tachyarrhythmias. The data of 250 patients [43 women (17.2%) and 207 men (82.8%)] with spontaneous sustained ventricular tachycardia [n = 190 (76%)] and fibrillation [n = 60 (24%)] who underwent coronary and left ventricular angiography, electrophysiological study, and signal-averaging electrocardiogram (ECG) form the basis of this analysis. No gender-related differences could be observed in age, number of diseased coronary arteries, history, location and number of myocardial infarctions, presence of left ventricular aneurysm, ejection fraction, type of spontaneous or induced arrhythmias, right ventricular effective refractory period, and signal-averaged ECG parameters. Age, presence of previous myocardial infarction, and ejection fraction were significant predictors (p < 0.001) of inducibility of sustained ventricular tachyarrhythmias. Once CAD has begun, female and male patients present similar clinical and electrophysiologic characteristics. Thus, both genders should benefit similarly from diagnostic and therapeutic approaches if they are referred to the hospital or to invasive interventions at similar intervals in the course of their illness.

Efficacy of ajmaline and propafenone in patients with accessory pathways: a prospective randomized study

In a prospective randomized study, we assessed the electrophysiologic effects and the efficacy of ajmaline versus propafenone in patients with accessory pathways (APs). During initiated atrioventricular (AV) reentrant tachycardia or atrial fibrillation (AF), ajmaline (1 mg/kg as bolus followed by infusion of 15 micrograms/kg/min) or propafenone (2 mg/kg, followed by infusion of 30 micrograms/kg/min.) were randomly administered intravenously (i.v.) in 40 patients with APs. AV reentrant tachycardia terminated in 15 of 16 patients (94%) on ajmaline and in 12 of 15 patients (80%, NS) on propafenone. AF ceased in 4 of 4 patients receiving ajmaline and in 3 of 5 patients receiving propafenone (n.s.). During continuous infusion of drugs, AV reentrant tachycardia became noninducible in 10 (50%) patients receiving ajmaline, as compared with 6 (32%) receiving propafenone (NS). Both drugs significantly prolonged the anterograde and retrograde effective refractory periods (ERPs) of the AP. There were no significant differences in changes in electrophysiologic parameters between the two drugs. Ajmaline and propafenone are highly effective and safe in terminating and preventing reinitiation of AV reentrant tachycardia or AF in patients with APs. Both drugs significantly prolonged the anterograde and retrograde ERPs of the APs.

Recurrence and late block of accessory pathway conduction following radiofrequency catheter ablation

INTRODUCTION

Many issues regarding the recurrence of accessory pathway conduction and the long-term outcome of late block of accessory pathway conduction are still unknown or controversial.

METHODS AND RESULTS

Data from 217 patients who underwent an initially successful radiofrequency ablation of accessory pathways and 7 patients with late block of accessory pathway conduction following an initially unsuccessful ablation were analyzed. During a mean follow-up of 19 +/- 11 months, accessory pathway conduction resumed in 21 (10%) of 217 patients following an initially successful ablation and in 6 (86%) of 7 patients with late block of accessory pathway conduction (P < 0.01). After initially successful ablations, the recurrence rates of accessory pathway conduction at 1, 3, and 6 months were 5.9%, 7.4%, and 11.3%, respectively. A late electrophysiologic study at 6 months uncovered recurrence in only 1 of 124 asymptomatic patients, but failed to detect the late recurrence in 2 patients in whom the accessory pathway conduction resumed after more than 6 months. Multivariate analysis revealed that independent predictors for recurrence of accessory pathway conduction were concealed accessory pathway, presence of transient effect of radiofrequency pulse, and more than 5 pulses required for initial cure. Accessory pathway location, length of the tip electrode of the ablation catheter, and repeat radiofrequency pulses ("safety pulses") after effective pulses did not predict resumption of accessory pathway conduction.

CONCLUSIONS

After initially successful ablation, the recurrence rates of accessory pathway conduction at 1, 3, and 6 months were 5.9%, 7.4%, and 11.3%, respectively. Late electrophysiologic testing had little prognostic value in asymptomatic patients following successful ablation. Application of "safety pulses" did not prevent recurrence. Late block of accessory pathway conduction did not predict long-term efficacy.

The role of implantable cardioverter defibrillators in dilated cardiomyopathy

Depending on the severity of the disease, patients with dilative cardiomyopathy (DCM) have a poor prognosis. No definite data are available to show that complex ventricular ectopy, the presence of ventricular late potentials, or programmed electrical stimulation in patients without symptoms with DCM identify patients at risk of sudden cardiac death. Although poor left ventricular function seems to be the most potent predictor of total cardiac death, the prediction of sudden death in patients without symptoms with DCM is poor. Studies with either class I antiarrhythmic drugs or amiodarone have not yet demonstrated a reduction in total mortality rates or sudden death. The usefulness of an implantable cardioverter defibrillator (ICD) in patients without symptoms with DCM is currently under investigation. The usefulness of serial electropharmacologic testing for patients with documented sustained ventricular tachycardia or ventricular fibrillation and DCM is still controversial. Because most patients with DCM and VT or out-of-hospital cardiac arrest have either no inducible ventricular tachyarrhythmia at baseline or the reproducibility of ventricular tachycardia/ventricular fibrillation induction is poor, implantation of an ICD should be considered in most of these patients. The indication for implantation of an ICD should be made on clinical judgment of the patient's functional status and other prognosis-limiting factors, such as rapid progression of heart failure, end-stage heart failure, and age.

Role of programmed ventricular stimulation in patients with idiopathic dilated cardiomyopathy and documented sustained ventricular tachyarrhythmias: inducibility and prognostic value in 102 patients

The role of programmed ventricular stimulation (PVS) in patients at high risk of sudden death related to idiopathic dilated cardiomyopathy (DCM) is still controversial. The possible reason is that most study series have been too small or that only a few patients had documented sustained ventricular tachyarrhythmias. This study therefore, looked at PVS performed in 102 patients with DCM and documented sustained ventricular tachycardia (VT; n = 63) or ventricular fibrillation (VF; n = 39). Sustained VT was induced in 27 of 63 patients (43%) with documented sustained VT and in 14 of 39 patients (36%) with documented VF (ns). VF was induced in nine patients (14%) with a history of sustained VT and in seven (18%) with a history of VF (ns). At a mean follow-up of 32 +/- 15 months, sudden death occurred in 14 (14%) patients, a rate similar in both patients with documented VT and VF (ns). Incidence of sudden death at 36 months was 6% in patients with inducible sustained VT/VF compared to 29% in patients without inducible VT/VF (P < 0.05). A favourable drug regimen (response to drug and no intolerable side effects) was obtained by serial drug testing in 25 of all 102 patients (25%). A cardioverter defibrillator (ICD) was implanted in 32 patients, in 63% of whom discharges were observed during 18 +/- 11 months of follow-up; only one patient (3%) died suddenly. Thus, in patients with DCM, there was no relationship between documented and inducible ventricular tachyarrhythmias, and initiation of sustained VT or VF had little prognostic value for the prediction of subsequent sudden death. Wherever antiarrhythmic drug therapy was of limited value, implantation of an ICD may improve the prognosis of these high risk patients.

Complete bilateral oculomotor palsy: the only clinical sign of subarachnoid hemorrhage in leukemia

We report the original case of a patient with acute myelogenous leukemia who presented with a painless, complete bilateral oculomotor palsy during induction chemotherapy. Headache, signs of meningeal irritation or further neurological symptoms were absent throughout the course of illness. The CT revealed a subarachnoid hemorrhage (SAH). Within a day of the onset of symptoms, the oculomotor palsy subsided completely with no residual damage. To our knowledge, this is the first described case of SAH in leukemia with complete bilateral oculomotor palsy being the only clinical symptom. Furthermore, the spontaneous remission of this pathological condition is an extremely rare event.

Electrophysiologic variables characterizing the induction of ventricular tachycardia versus ventricular fibrillation after myocardial infarction: relation between ventricular late potentials and coupling intervals for the induction of sustained ventricular tachyarrhythmias

OBJECTIVES

The aim of this study was to analyze the relations between the presence of ventricular conduction delay and the necessary coupling intervals for the induction of sustained ventricular tachyarrhythmias.

METHODS

The electrophysiologic and signal-averaged electrocardiographic (ECG) data from 83 patients with previous myocardial infarction and inducible sustained monomorphic ventricular tachycardia (n = 71) and ventricular fibrillation (n = 12) were analyzed.

RESULTS

The sum of the coupling intervals needed for inducing ventricular tachycardia and ventricular fibrillation was 485 +/- 59 ms and 387 +/- 36 ms, respectively (p < 0.001). The mean difference between the effective refractory period and the second coupling interval for the induction of ventricular tachycardia and ventricular fibrillation was -3 +/- 40 ms and 24 +/- 29 ms, respectively (p < 0.02). QRS duration and duration of terminal low amplitude signals of the QRS complex (p < 0.004) were longer in patients with inducible ventricular tachycardia than in patients with inducible ventricular fibrillation. The root mean square of the voltage during the last 40 ms of QRS complex was lower in patients with inducible ventricular tachycardia than in patients with inducible ventricular fibrillation (p < 0.007). Patients with inducible ventricular tachycardia presented with a greater prevalence of ventricular late potentials than that of patients with inducible ventricular fibrillation (p < 0.007). For arrhythmia induction, significantly shorter coupling intervals were necessary in patients without than in patients with ventricular late potentials. A positive correlation was found between the cycle length of the induced ventricular tachycardia and the filtered QRS duration as well as with the sum of the coupling intervals.

CONCLUSIONS

Induction of ventricular fibrillation requires shorter coupling intervals than does induction of ventricular tachycardia. The presence of ventricular conduction delay seems to be a marker of facilitated induction of sustained monomorphic ventricular tachycardia rather than of ventricular fibrillation. The coupling intervals required to induce ventricular tachycardia or fibrillation are longer in patients with than in those without an abnormal signal-averaged ECG.

Catheter ablation of ventricular tachycardia using radiofrequency current

Catheter ablation techniques have evolved as an alternative to map-guided surgery and proven effective in a variety of supraventricular tachyarrhythmias. Direct current catheter ablation has been shown to be effective in about 50 to 70% of cases. Approximately, 60% of patients with structural heart disease and monomorphic ventricular tachycardia were successfully treated using direct current ablation techniques. This overall success rate and possible risks associated with the use of direct current have stimulated the search for other energy sources appropriate for catheter ablation. Presently, only a few preliminary reports on the clinical efficacy of radiofrequency energy for the treatment of ventricular tachyarrhythmias in man exist. 23 patients with identifiable heart disease at a mean age of 52 +/- 17 years underwent radiofrequency catheter ablation. 16 patients had coronary artery disease, one patient dilative cardiomyopathy and six patients had arrhythmogenic right ventricular disease. All patients presented with chronic current sustained ventricular tachycardia. After detailed endocardial catheter mapping radiofrequency energy was applied at the site of earliest ventricular activation during ventricular tachycardia which could be entrained during fixed rate ventricular pacing at the site of origin of ventricular tachycardia. At all ablation sites a long latency between the stimulus and QRS complex was noted. Of 23 patients 18 were treated with radiofrequency alone whereas in five patients a second ablation procedure using direct current was performed. Following the ablation procedures, 14 patients (61%) remained free of ventricular tachycardia. One patient died due to congestive heart failure 21 months following ablation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of enflurane on inducibility of ventricular tachycardia

The effects of enflurane on cardiac electrophysiologic parameters and on inducibility of ventricular tachycardia (VT) by programmed stimulation were studied in 12 patients (11 men, 1 woman, mean age +/- standard deviation 55 +/- 8 years) with drug refractory sustained monomorphic VT who underwent transcatheter ablation with high-energy direct-current shocks. One catheter ablation procedure was performed in 10 patients, whereas 2 ablation sessions were necessary in 2 patients. Programmed ventricular stimulation was performed on 2 separate days (mean interval 19). There were 2 baseline studies, 1 several days before ("baseline study I") and the second at the beginning of the ablation procedure ("baseline study II") while the patient was awake and nonsedated. The third programmed stimulation study was done 15 to 30 minutes after administration of anesthesia with enflurane, oxygen and nitrous oxide ("enflurane study"). Rate of sinus rhythm, QRS duration, PQ interval and ventricular effective refractory period were unaltered, whereas QTc interval increased significantly after initiation of anesthesia. Before and after induction of general anesthesia, clinical VT was inducible in all patients. However, in 1 patient, induction of VT was only possible by pacing in the left ventricle after enflurane administration. Based on these data, it is concluded that general anesthesia with enflurane, oxygen and nitrous oxide has no marked influence on inducibility of clinical VTs. Therefore, this type of anesthesia may be useful for nonpharmacologic, ablative procedures requiring general anesthesia.

Acute and long-term efficacy of oral propafenone in patients with ventricular tachyarrhythmias

The class Ic antiarrhythmic agent propafenone was studied by repeated electrophysiologic testing in 54 patients (43 male, aged 54 +/- 10 years, mean ejection fraction of 37.3 +/- 16.9%) with ventricular tachyarrhythmias. Forty patients (74%) had coronary artery disease. Programmed ventricular stimulation (S2, S2S3 during sinus rhythm and/or during S1S1 = 500, 430, 370, and 330 ms) off antiarrhythmic drugs induced sustained ventricular tachycardia, flutter, or fibrillation in all patients. After 450-900 mg of oral propafenone/day for 4-7 days, 51 patients were restudied. In the remaining three patients, spontaneous ventricular tachycardia occurred on drug therapy. Tachycardia induction was suppressed in 9 of 51 patients restudied (18%) and rendered more difficult to induce (basic stimulation drive greater than or equal to 40 beats/min higher than at control study) in another 7 patients (14%) (overall efficacy of 31%). The tachycardia rate decreased from 220 +/- 43 to 177 +/- 44 beats/min (p less than 0.01). The right ventricular effective refractory period increased from 232 +/- 22 to 252 +/- 22 ms (p less than 0.001). Responders to propafenone therapy had higher rates of inducible ventricular tachycardia at control (greater than 230 beats/min: 43%; less than or equal to 230 beats/min: 21%; p less than 0.05), higher ejection fractions, and lower left ventricular end-diastolic pressures than nonresponders. Eleven of the 16 patients showing a positive response to propafenone therapy in electrophysiologic testing were discharged on propafenone alone. During follow-up (17 +/- 12 months), nine patients remained free from ventricular tachycardia, one patient had a relapse, and one patient died of noncardiac death.(ABSTRACT TRUNCATED AT 250 WORDS)

[Catheter ablation in ventricular tachycardia]

The basis for management of ventricular tachycardia (VT) is pharmacologic treatment which is effective, however, in only about 20 to 30% of the patients. With respect to this problem, alternative therapeutic modes have been developed which include, in addition to antitachycardia stimulation, electrical, palliative therapy such as the implantable automatic defibrillator, definitive measures such as map-guided antitachycardia surgery and catheter ablation. The goal of catheter ablation is the selective destruction of heart structures which are the morphologic correlate for initiation of propagation of VT. Catheter ablation was discovered by chance by Fontaine after a defibrillation during an electrophysiologic study in which a defibrillating electrode in the proximity of a catheter at the His bundle induced complete AV-block. This effect of destruction in the AV-conduction system by direct current as a therapeutic measure was further developed by Gallagher and Scheinman. The mechanism held responsible is coagulation by the electrode of neighboring tissue and barotrauma. The technique, which was initially used for ablation of the His bundle in supraventricular tachycardia, can also be used for ablation of accessory pathways or the site of origin of VT which generally lies endocardially in marginal regions of myocardial infarctions. CATHETER MAPPING: In sinus rhythm and induced VT, endocavity catheter mapping is carried out after heparinization with electrocardiograms recorded from at least six to ten sites in the right and left ventricles. At the site of early activation, detailed mapping is used for identification of the site of earliest activation, then pace-mapping is performed during sinus rhythm and VT. The morphology of the stimulated QRS complexes is compared with that of the spontaneous VT. In patients in whom VT cannot be induced, localization is carried out by pace-mapping alone. CATHETER ABLATION: After localization, in intubation narcosis and with continuously monitored arterial blood pressure, the suspected site of origin of the VT is subjected to an initial shock during sinus rhythm by means of a distal electrode of a catheter in stable contact with the endocardium. For mapping and ablation, the same catheter is used. After each subsequent shock, assessment is performed to determine if the distal electrode pair still conducts local ventricular signals and if ventricular stimulation is possible. The shock energy delivered is 100, 200 or 400 Joules. At the time of shock discharge, the remaining electrodes or catheters are disconnected. In the case of bradycardia or tachycardia after the shock, immediate connection to an external stimulation generator is established. At the time of the shocks, relaxation is provided by succinylcholine. All shocks are delivered from the anode. The integrity of the catheter is tested after each shock, no catheter is used more than three or four times. At the earliest, ten minutes after shock delivery, induction of clinical VT is attempted with programmed stimulation and if induction is possible, at the same site a maximum of two more shocks are delivered or, after renewed mapping, another shock is delivered to a different site. Induced non-clinical VT is not subjected to ablation.(ABSTRACT TRUNCATED AT 400 WORDS)

Diagnostic value of electrocardiographic variables to predict the presence of ventricular late potentials

To test the hypothesis that the presence of ventricular late potentials in the highly amplified, averaged and filtered surface electrocardiogram (ECG) can be predicted from the conventional surface ECG, 211 patients with and without previously documented sustained ventricular tachycardia outside the acute phase of myocardial infarction were studied. The presence of left ventricular akinesia or aneurysm was significantly correlated with the ECG score (based on Q wave duration, R wave duration and amplitude ratio). The mean ECG score in patients without ventricular tachycardia was 3.4 +/- 3.5 points compared with 5.5 +/- 3.9 points (p less than 0.001) in patients with ventricular tachycardia. The presence of late potentials was positively correlated with the ECG score in the whole cohort of patients. This was also the case in the subgroup of patients without a history of sustained ventricular tachycardia. In contrast, in patients with ventricular tachycardia, the presence of late potentials was independent of their ECG score. Using linear discriminant function analyses to predict the presence of late potentials, a history of ventricular tachycardia alone and the ECG score alone had a high predictive power (high standardized coefficients). If combinations of variables were analyzed including estimates of left ventricular function (presence of aneurysm or akinesia; ejection fraction), the ECG score and a history of ventricular tachycardia still ranked highest. The influence of ejection fraction if used in combination with other variables for the prediction of late potentials was relatively small (standardized coefficient of 0.4). In conclusion, the surface ECG can be used in patients previously free of sustained ventricular tachycardia to predict the presence of ventricular late potentials.(ABSTRACT TRUNCATED AT 250 WORDS)

[Behavior of ventricular late potentials following catheter ablation of ventricular tachycardia]

In 10 patients non-invasively recorded signal-averaged electrocardiograms were obtained before and after direct-current ablation of ventricular tachycardia (right ventricular origin n = 5; left ventricular origin n = 5). The algorithms proposed by Simson and Karbenn et al. were used (modified Frank leads, high-pass filter cut-off frequency 25 Hz). No differences were observed between the mean values of the duration of the QRS-complex, the mean voltage during the last 40 ms of the QRS-complex, the duration of the late potentials and the number of patients having late potentials before and after ablation, respectively. The success of ablation could not be predicted by the signal-averaged ECG. There was no difference between the averaging parameters of those patients without recurrences of ventricular tachycardia during the follow-up period and those with (n = 3). Thus, the signal-averaged ECG did not prove helpful in predicting a successful outcome of direct-current catheter ablation of ventricular tachycardia.

Pathophysiological mechanisms of ventricular tachyarrhythmias

The pathophysiological background for ventricular tachyarrhythmias based on experimental and clinical evidence is presented. Sudden cardiac death may occur as the first manifestation of coronary artery disease without antecedent complaints or it may occur in patients with a previous myocardial infarction. In the latter situation, a circumscribed area of cardiac tissue may be responsible for the genesis and maintenance of a ventricular tachyarrhythmia which may be called the 'arrhythmogenic substrate'. This zone of electrically abnormal ventricular myocardium is usually located at the border of a previous myocardial infarction, and is characterized by islands of relatively viable muscle alternating with areas of necrosis and, later, fibrosis. The consequent fragmentation of the propagating electromotive forces leads to the development of high-frequency components that can be recorded directly or non-invasively using signal-averaging techniques. These signals have been called ventricular late potentials. The 'arrhythmogenic substrate' may be present permanently or may rise acutely and be present only transiently in the case of extensive ischaemia or acute myocardial infarction. In the setting of a chronic 'arrhythmogenic substrate', this electrically abnormal tissue may be triggered by spontaneously occurring ventricular ectopic beats or salvoes or by programmed ventricular stimulation, as well as by transient episodes of ischaemic causing spontaneous arrhythmias. These trigger factors modify the 'arrhythmogenic substrate' in such a way that ventricular tachyarrhythmias are sustained. It is apparent that sudden cardiac death is due to a wide spectrum of pathophysiological mechanisms which may be interrelated. There is obviously no single parameter that helps the clinician to predict the propensity for sudden cardiac death in the individual patient.

Catheter ablation of ventricular tachycardia using defibrillator pulses: electrophysiological findings and long-term results

Catheter ablation of ventricular tachycardia (VT) was attempted in 24 patients (mean age 49 +/- 15.1 years) with a history of recurrent sustained VT resistant to previous antiarrhythmic drug therapy. 14 patients (58.3%) had also failed to respond to long-term administration of amiodarone alone and in combination with class I antiarrhythmic drugs. Endocardial catheter mapping during induced or spontaneous VT and/or pacemapping were performed to identify the site of origin of VT. Direct-current high-energy anodal shocks were delivered from a conventional cardioverter with stored energies of 100, 200 or 400 J via the distal electrode of conventional catheters. A total of 139 shocks was delivered during the ablation procedure. One patient died from wall perforation. Within 1 week of ablation, nine patients developed spontaneous recurrences of monomorphic sustained VT, identical to the clinical VT, and one patient developed a VT with a new morphology. In addition, four patients had a recurrence of their clinical VT after several weeks. In seven of 14 patients with spontaneous recurrences after the first ablation procedure and in three patients in whom VT was again inducible at the end of the first week, a second ablation procedure was performed. One patient with inducible VT after the first and second ablation sessions was given a third ablation procedure, and was discharged from hospital on anti-arrhythmic drugs which were successful despite being previously ineffective. After a mean follow-up period of 14.1 +/- 9.1 months, there were no spontaneous recurrences of sustained VT in 17 patients (71%) (nine without antiarrhythmic drugs and eight on antiarrhythmic drugs). In the remaining patients, incessant non-sustained VT (n = 2) or recurrent sustained VT (n = 2) occurred, and two patients died suddenly (at 2 and 21 months). There was no correlation between catheter mapping data or the results of pre-discharge electrophysiological study and clinical outcome during long-term follow-up. Complications related to catheter ablation included pulmonary oedema, cardiac tamponade, femoral artery occlusion, multiple episodes of ventricular tachycardia/fibrillation and thrombus formation, each in one patient (major complications; n = 7,29.1%), as well as transient third degree AV block, transient right or left bundle branch block, transient marked ST elevation or transient atrial tachycardia (minor complications; n = 8, 33.3%). The results suggest that catheter ablation might become an effective procedure for the non-pharmacological treatment of sustained VT.(ABSTRACT TRUNCATED AT 400 WORDS)

Termination of re-entrant ventricular tachycardia by subthreshold stimulus applied to the zone of slow conduction

A 52-year-old female patient developed recurrent sustained ventricular tachycardia during the first week after left ventricular aneurysmectomy. The patient had no history of ventricular tachycardia preoperatively. As her tachycardias proved to be resistant to several antiarrhythmic drugs, catheter ablation was considered. To define the site of origin of ventricular tachycardia, endocardial catheter mapping and pace-mapping were performed. In addition, the response to single premature stimuli applied during ventricular tachycardia was assessed. At a site in the basal portion of the antero-septal area of the left ventricle, early presystolic endocardial activity during ventricular tachycardia was found. Continuous pacing as well as premature stimulation from that site showed a marked delay between the stimulus artefacts and the induced QRS complexes. The stimulus-induced QRS complexes were identical to QRS complexes of spontaneous and induced ventricular tachycardia. At very short critical coupling intervals of single premature stimuli that did not capture the ventricles (non-propagated stimuli), ventricular tachycardia was reproducibly terminated. These findings are explained by assuming that the catheter was located within the zone of slow conduction of the re-entrant circuit, possibly in its proximal portion.

Prognostic significance of ventricular late potentials in the postmyocardial infarction period

Ventricular late potentials in patients after myocardial infarction can be assumed to herald an increased risk of future sudden cardiac death or symptomatic sustained ventricular tachycardia. This holds particularly true for patients studied early after recent myocardial infarction whereas patients assessed later in the subsequent course have a substantially lesser incidence of arrhythmic events, probably due to intercurrent death of those at high risk. Of prognostic importance appears not only the presence but also the duration of late potentials. A meaningful role is also assumed by the extent of left ventricular functional impairment (EF less than 40%). However, in consideration of the complex mechanisms that can lead to sudden cardiac death, no single method predicts with high sensitivity the occurrence of a ventricular tachyarrhythmic event. Sudden cardiac death can be incurred on the basis of chronic electrophysiological abnormalities as a consequence of regional slow conduction in the border zone of a previous myocardial infarction precipitated by trigger factors such as spontaneous ventricular arrhythmias. Sudden cardiac death or symptomatic sustained ventricular tachycardia can also occur due to sudden and transient changes in the electrophysiological properties of the myocardium due to ischemia. Whether the combination of late potentials with clinical parameters such as ventricular arrhythmias detected in the ambulatory ECG and those induced with programmed electrical stimulation will lead to more accurate identification of patients at risk prerequisites further elucidation. Currently available literature indicates that in patients with late potentials, ventricular tachycardias can be induced more frequently by programmed electrical stimulation and that the combination of both phenomena confers a particularly high risk.

Effects of non-pharmacological interventions on ventricular late potentials

The purpose of the paper is to review the presently available information of the effects of non-pharmacological interventions for the control of drug-refractory ventricular tachyarrhythmias on non-invasively recorded ventricular late potentials. During recent years, non-pharmacological interventions have evolved as an alternative form of treatment to control drug-refractory ventricular tachyarrhythmias. The effects of these non-pharmacological measures on ventricular late potentials are poorly understood. Successful surgical control of ventricular tachycardia often normalizes the signal averaged ECG and may eliminate delayed potentials. Thus, this non-invasive test may be useful in assessing surgical efficacy in subgroups of patients with ventricular tachycardia. However, the clinical value of late potentials in assessing surgical efficacy in the individual case may be limited as the sensitivity and specificity of the loss of late potentials after antitachycardia surgery are low. In addition, the effects of transvenous catheter ablation on ventricular late potentials will be reviewed. The available information suggests that this intervention has little effects on the presence or absence of late potentials. Thus, non-invasive recording of late potentials seems not to be helpful in predicting the acute and long-term efficacy of catheter ablation. In conclusion, changing of the parameters in the signal-averaged QRS complex after antitachycardia surgery may be useful in predicting the efficacy of surgical interventions for drug-refractory ventricular tachycardias in subgroups of patients. However, the sensitivity and predictive accuracy of this test are low, thus limiting its clinical usefulness.