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Biomedical subjects

G Breithardt

Publications and source records attributed to G Breithardt.

At least 235 records · Page 13Linked to original sources
PubMed1995

Radiofrequency catheter ablation of sustained ventricular tachycardia in idiopathic dilated cardiomyopathy.

BACKGROUND: The feasibility of radiofrequency (RF) catheter ablation for the treatment of sustained ventricular tachycardia (VT) in patients with coronary artery disease and remote myocardial infarction has recently been demonstrated. At present, therapeutic options for VT in patients with idiopathic dilated cardiomyopathy (DCM) include antiarrhythmic drugs and implantable cardioverter/defibrillators (ICD). The purpose of the present study was to investigate the feasibility of RF catheter ablation in patients with idiopathic DCM who could not be adequately treated by conventional treatment modalities because of incessant or frequent, recurrent VT. METHODS AND RESULTS: RF current application for ablation of 9 VTs (mean cycle length, 402 +/- 78 ms) was attempted in 8 patients with idiopathic DCM (4 men, 4 women; mean age, 54 +/- 6 years; mean left ventricular ejection fraction, 30 +/- 9%). Inclusion criteria for ablation were incessant VT (n = 4) or frequent, recurrent VT reproducibly inducible with programmed electrical stimulation (n = 5). Three patients had suffered aborted sudden cardiac death, and 2 had experienced syncope. Two patients were artificially ventilated and catecholamine dependent for hemodynamic reasons at the time of attempted ablation. Potential target sites for RF current application were identified by detailed endocardial mapping during sinus rhythm, activation and entrainment mapping during VT, and pace mapping. After 7 +/- 5 RF pulses (range, 2 to 18 pulses; median, 6 pulses) applied with 32 +/- 7 W for 39 +/- 9 seconds, 6 of the 9 target VTs (67%) were rendered noninducible (4 of 4 incessant VTs and 2 of 5 chronic recurrent VTs). In 6 patients, VTs with ECG morphologies other than the target VTs were inducible after RF catheter ablation. Seven patients were on antiarrhythmic drugs during the ablation procedure and during the follow-up period of 8 +/- 5 months (range, 2 to 17 months). One patient received an ICD before RF ablation, 4 patients after RF ablation, and 1 patient after ablation of an incessant VT and before attempted ablation of frequent, recurrent VTs. One patient underwent heart transplantation 5 months after ablation in end-stage heart failure. There were no acute complications during the mapping and ablation procedure. During the follow-up period, 1 patient had been resuscitated from ventricular fibrillation 6 weeks after ablation and finally died of congestive heart failure 2 weeks later. No further episodes of incessant VT occurred in the patients who had undergone RF current application for ablation of incessant VT. A complete prevention of VT could be achieved in 2 of 8 patients, whereas in 5 patients, VT episodes were stored in the ICD devices during follow-up. CONCLUSIONS: The results of the present study indicate that RF current application for ablation of VT in a select group of patients with idiopathic DCM is feasible. The efficacy of RF ablation may be high in patients presenting with incessant VT, whereas the success rate seems to be only moderate in patients with chronic recurrent VT. In all patients, additional treatment options, including antiarrhythmic drugs, ICDs, and/or heart transplantation, were applied after RF ablation, indicating that RF ablation for this indication may be an adjunctive and not a curative treatment option.

Anti-Arrhythmia Agents↗
PubMed1995

The Interdisciplinary Heart Failure and Transplant Program Münster: a 5-year experience.

The variety and complexity of therapeutic options available for the increasing number of patients with advanced chronic heart failure has lead to the institution of specialized heart failure/heart transplant programs. The central task consists of carefully evaluating and selecting potential transplant recipients, based on the comparative benefit rationale, i.e. the expected gain in life expectancy and quality of life by cardiac transplantation compared with all other treatment options. Further tasks include a comprehensive chronic heart failure management, high risk conventional cardiac surgery, mechanical and antiarrhythmic bridging and dedicated posttransplant care. This concept is described on the basis of the 5-year experience of the Interdisciplinary Heart Failure and Transplant Program Münster.

Cardiology Service, Hospital↗
PubMed1995

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.

Age Factors↗
PubMed1995

Molecular analysis at the Harvey Ras-1 gene in patients with long QT syndrome.

Patients with long QT syndrome (LQTS; MIM 1921500) frequently suffer from syncope and are threatened by sudden cardiac death due to ventricular arrhythmias, typically of the torsade de pointes type. Initial progress in revealing the molecular basis of the disease was made by the observation of genetic linkage of the disease locus to the Harvey Ras-1 gene (HRAS 1) on chromosome 11p15.5. More recently loci on chromosomes 3, 4, and 7 have also been found to be linked to LQTS, thus demonstrating heterogeneity in the causes for this disease. The present study performed sequence analysis on the HRAS 1 gene in patients with congenital and acquired LQTS to determine the frequency of HRAS 1 mutations in patients with this disease. In neither group were no mutations identified in the coding regions or in the splice donor and acceptor sites. Alleles characterized by a T to C transition in exon 1 and an insertion/deletion polymorphism upstream of exon 1 showed no significant difference in their frequencies between LQTS patients and normal controls. No quantitative influence of the such characterized genotypes on the QT duration was observed. These results demonstrate that structural mutations in the HRAS 1 gene are not a frequent cause of LQTS. Also, since there was no association of different alleles at the HRAS 1 locus with changes in QT duration, it appears unlikely that this gene is a major contributor to this disease.

Alleles↗
PubMed1995

Electrophysiologic effects of potassium channel openers.

Potassium-channel openers or activators have been introduced as a new class of antihypertensive and antianginal agents that act by increasing membrane conductance to potassium, mainly through augmentation of the ATP-sensitive potassium current. Recent in vitro studies have shown that K(+)-channel openers exert concentration-dependent effects on cardiac electrophysiology. A shortening of the cardiac action potential by acceleration of repolarization has been reported in multicellular preparations as well as in isolated myocytes. However, drug concentrations that affect the action potential duration of myocardial cells are considerably higher (10- to 100-fold) than those needed for effects on vascular smooth muscle cells. Studies in which mostly high concentrations of K(+)-channel openers were used have demonstrated that these drugs may accelerate automaticity and may promote reentrant activity. Particular interest has focused on the question whether opening of potassium channels may be potentially arrhythmogenic in the setting of acute myocardial ischemia. On the other hand, recent studies have shown that K(+)-channel openers are effective in suppressing polymorphic ventricular tachyarrhythmias induced by early afterdepolarizations and triggered activity in vivo. The clinical relevance of these experimental studies to the clinical situation is still unclear. Some K(+)-channel openers have been shown to produce electrocardiographic T-wave changes in patients in whom their effectiveness as antihypertensives was tested. However, this effect was not associated with adverse effects and has not been demonstrated for all compounds.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Intracoronary stenting after unsuccessful PTCA. Early restenosis and explanation of stents during bypass surgery.

The case of a 63-year-old man is described, who received two intracoronary Palmaz-Schatz-Stents after dissection and occlusion following PTCA of two segments of the left anterior descending branch of the left coronary artery. Because of recurrent angina caused by early restenosis in the 'unprotected' segment between the stents, surgical revascularisation was performed and the stents were removed.

Angina Pectoris↗
PubMed1995

Angiographic, intravascular ultrasound and functional findings early after orthotopic heart transplantation.

Accelerated graft atherosclerosis is responsible for increased mortality and morbidity among heart transplant recipients. The aim of this in-vivo study was to evaluate coronary atherosclerotic vessel alterations and endothelial function. Seventeen patients (14 males; mean age 49.3 years; range 24 to 69) were studied an average of 11 weeks (range 5 to 21) after heart transplantation because of coronary artery disease (n = 8), dilative cardiomyopathy (n = 7), mitral valve replacement (n = 1) and left atrial metastases of a leiomyosarcoma (n = 1). Mean age of the donor hearts (9 males) was 29 years (range 12 to 55). All recipients underwent biplane ventriculography and coronary angiography. In this study population, a total of 120 coronary segments (main stem, 21; left anterior descending artery, 85; circumflex artery, 14) were analyzed by intravascular ultrasound (20 MHz, 3.5F). In 13 patients, acetylcholine was infused into the proximal left anterior descending artery (10(-8) to 10(-5) M) to evaluate vasomotion within this segment. Regional contraction abnormalities were documented in 2 patients. Nine segments angiographically showed non-critical stenoses (5 patients). Intravascular ultrasound detected 52 cross-sectional areas with a three-layer pattern indicating intimal thickening. Mean circumferential extension of intimal proliferation was 192 degrees, mean intimal thickness 0.35 mm. Only 5 segments of the sonographically pathological cross-sectional areas showed angiographical evidence of atherosclerotic lesions. Intracoronary administration of acetylcholine at doses of 10(-8) and 10(-7) M resulted in vasoconstriction of the examined coronary segment in only 2 patients; the intracoronary application of acetylcholine at doses of 10(-6) and 10(-5) M revealed coronary vasoconstriction in 10 of the total of 13 patients. Using intravascular ultrasound, coronary artery lesions in heart transplant recipients can already be depicted at a very early stage. The abnormal response to acetylcholine in most of the heart recipients is independent of the extent of atherosclerotic vessel abnormalities documented by ultrasound or angiography.

Acetylcholine↗
PubMed1995

Clinical and invasive 7-month follow-up of a patient with a synthetic coronary graft.

The PossisR polytetrafluoroethylene Permaflow is a synthetic coronary graft which incorporates a Venturi resistor and which is anastomosed to the superior vena cava. Multiple anastomoses to the coronary vessels can be established in sequence until the graft is finally connected to the aorta. This aortocaval fistula enables permanent flow within the synthetic graft. We present the post-operative clinical and invasive findings of a 69-year-old female patient with a PossisR coronary graft. Follow-up angiography 3 and 7 months post-operatively showed patency of both coronary anastomoses and sufficient run-off to the native vessel segments. The left-right shunt induced by the graft was hemodynamically insignificant. Left ventricular function had improved significantly. 30 MHz intravascular ultrasound of the proximal part of the PossisR graft did not show an extra inner layer at the luminal side of the synthetic graft wall, so that relevant intimal thickening could be excluded after an interval of 7 months post implantation. Using an intravascular imaging technique, focal atherosclerotic lesions or thrombotic graft wall alterations could also be ruled out.

Aged↗
PubMed1995

Localization and radiofrequency catheter ablation of left-sided accessory pathways during atrial fibrillation. Feasibility and electrogram criteria for identification of appropriate target sites.

OBJECTIVES: The purpose of the present study was to assess the feasibility of and electrophysiologic criteria for successful radiofrequency catheter ablation of left-sided accessory pathways during atrial fibrillation in patients with Wolff-Parkinson-White syndrome. BACKGROUND: The onset of recurrent or sustained atrial fibrillation can complicate or significantly prolong accessory pathway catheter ablation procedures. METHODS: We studied 19 consecutive patients (mean age [+/-SD] 44 +/- 16 years) with Wolff-Parkinson-White syndrome who had ongoing atrial fibrillation with rapid anterograde conduction over the accessory pathway (mean ventricular rate [+/-SD] 173 +/- 26 beats/min, range 130 to 220) at the beginning of the localization procedure during radiofrequency catheter ablation. Localization and ablation of the accessory pathway were performed with a 7F deflectable catheter (4-mm tip) that was placed underneath the mitral valve annulus. The electrophysiologic criteria from unipolar and bipolar local electrograms were compared for successful (n = 18) and unsuccessful (n = 39) sites. RESULTS: The accessory pathways were localized in the left posteroseptal (n = 6), posterior (n = 1), posterolateral (n = 7) and lateral (n = 5) regions and successfully ablated during atrial fibrillation in 18 (95%) of 19 patients with a mean of 3 +/- 2 radiofrequency pulses (range 1 to 8, median 2). Presence of an accessory pathway potential (94% vs. 44%), early activation time of the ventricular electrogram (-3.2 +/- 9.2 vs. -15.3 +/- 12.6 ms) and recording of atrial activation (88% vs. 61%) from the ablation catheter were helpful in identifying successful sites (p < 0.001, p < 0.001 and p < 0.05, respectively, compared with unsuccessful sites). In addition, the ventricular activation time in relation to the intrinsic deflection of the unipolar electrogram was significantly earlier at successful than unsuccessful sites (18.1 +/- 4.8 vs. 24.4 +/- 6.6 ms, p < 0.01). A QS complex on the unipolar electrogram was observed at 96% of successful sites and at 94% of unsuccessful sites (p = 0.74). Multivariate logistic regression analysis revealed that the presence of an accessory pathway potential (p < 0.002) and early ventricular activation time in relation to the onset of the QRS complex (p < 0.001) were independent predictors of ablation success. CONCLUSIONS: Localization and radiofrequency catheter ablation of left-sided accessory pathways is possible in patients with sustained atrial fibrillation and rapid anterograde conduction over the accessory pathway during the ablation procedure. The electrophysiologic criteria described here can be used to reliably identify successful sites for radiofrequency ablation.

Adult↗
PubMed1995

An anatomically and electrogram-guided stepwise approach for effective and safe catheter ablation of the fast pathway for elimination of atrioventricular node reentrant tachycardia.

OBJECTIVES: We describe a new stepwise anatomically and electrogram-guided strategy for radiofrequency catheter ablation of the fast pathway. BACKGROUND: Anatomically and electrogram-guided approaches have been developed for slow pathway ablation in patients with atrioventricular (AV) node reentrant tachycardia; however, no stepwise systematic approaches exist for fast pathway ablation. METHODS: Fifty-three patients (mean [+/- SD] age 43 +/- 11 years) with AV node reentrant tachycardia underwent attempted ablation of the fast pathway. The ablation catheter was initially positioned posterior and slightly superior to the site of the maximal His bundle recording region. At these sites, the amplitude of the local atrial potential was usually at least twice as high as the local ventricular potential, and a small proximal His bundle potential was recorded. When the first pulse was ineffective, the ablation catheter was repositioned stepwise slightly inferior to more midseptal sites. RESULTS: After a mean of 3.4 +/- 3.1 radiofrequency pulses (median 2, range 1 to 12), AV node reentrant tachycardia was noninducible in 51 patients (96%). No inadvertent complete AV block occurred. The AH interval was prolonged from 79 +/- 19 to 145 +/- 37 ms (p < 0.001). Thirty-eight patients (72%) developed complete ventriculoatrial block. Recording of a His bundle potential at the target site, stability of the local electrograms and occurrence of fast junctional rhythms during energy applications were more often observed at successful sites than transiently effective or noneffective sites. During a follow-up period of 12 +/- 7 months, 3 (6%) of 51 patients had a clinical recurrence of AV node reentrant tachycardia. CONCLUSIONS: Radiofrequency catheter ablation of the fast pathway using a combined anatomically and electrogram-guided stepwise approach is highly effective and safe. The safety of this approach seems to be due to the stable position of the ablation catheter at the interatrial septum, rather than across the tricuspid annulus, and the larger distance to the central body of the AV node and bundle of His.

Adult↗
PubMed1995

Prognosis and risk stratification after myocardial infarction.

In order to assess prognosis after myocardial infarction, various methods have been used: estimation of ejection fraction, Holter monitoring, detection of ventricular late potentials using signal-averaging techniques, programmed ventricular stimulation of the heart to test the inducibility of ventricular tachyarrhythmias, and parameters that assess heart rate variability. Left ventricular dysfunction is the major determinant for prognosis after myocardial infarction, but left ventricular end-systolic volume may be better than overall ejection fraction. The presence of an 'arrhythmogenic substrate' may be detected by recording low-amplitude, fractionated activity or by artificially introducing premature ventricular extrasystoles using programmed ventricular stimulation. The signal-averaged ECG represents an independent tool for risk assessment. In some studies, signal-averaging and programmed ventricular stimulation proved to be more sensitive for the prediction of sustained ventricular tachycardia than for sudden death. The risk of an arrhythmic event in patients with an abnormal signal-averaged ECG or an abnormal result of programmed ventricular stimulation is increased, although the majority of these patients still do not experience a fatal or life-threatening arrhythmia. This high number of false-positive results limits the practical applicability of the signal-averaged ECG but also of other techniques such as long-term ECG recording. Recent interest has focussed on heart rate variability, which is considered an index of sympatho-vagal interaction after acute myocardial infarction. Patients with decreased heart rate variability have a poorer prognosis than those with normal parameters. Patency of the infarct-related artery is a major factor that governs the potentially beneficial effects of thrombolytic therapy. Many, but not all, studies have shown a reduced prevalence of late potentials after successful thrombolysis or in the presence of an open infarct-related artery. Effective thrombolytic therapy may prevent the development of an abnormal electrophysiological milieu after myocardial infarction. Finally, neurological factors such as depression have been shown to be independent risk factors for mortality after acute myocardial infarction. The role of psycho-social factors and their mechanisms of action need further attention since they open the door for behavioural modification. In conclusion, there are several promising new techniques for identification of patients at risk of ventricular tachyarrhythmias. These techniques seem to be superior to more conventional methods such as long-term ECG monitoring as well as exercise testing. Methods which determine the arrhythmogenic substrate might be combined with a parameter of left ventricular ejection fraction because of the paramount importance of left ventricular pump function. However, due to the large proportion of false-positive results obtained with any of these methods, it seems unlikely that they will clearly surpass the others and be sufficiently accurate for risk assessment in the individual patient.

Electrocardiography↗
PubMed1995

Clinical implications of pleomorphic ventricular tachycardias on oral sotalol therapy.

In 90 consecutive patients with coronary artery disease and sustained monomorphic ventricular tachycardia, who were treated with oral sotalol and underwent programmed stimulation to determine drug effectiveness, the influence of sotalol on induced ventricular tachycardia morphology was retrospectively examined. In 54 patients (60%) sotalol rendered the tachycardia non-inducible. However, contrary to drug-testing with class I antiarrhythmic agents, induction of multiple morphologies at baseline study did not predict failure of subsequent drug-testing with sotalol. In the remaining 36 patients (40%), in whom sotalol did not modify inducibility, 21 patients (i.e. a total of 23%) manifested at least one new morphology during electropharmacological testing on sotalol. This effect was independent of the degree of left ventricular dysfunction, infarct location and numbers of morphologies at baseline, but corresponded with drug-induced changes in refractoriness. This observation may be related to a proarrhythmic effect of sotalol. Slowing of ventricular tachycardia rate and changes in morphology may have implications in patients receiving implantable cardioverter-defibrillators or those undergoing ablative procedures.

Administration, Oral↗
PubMed1995

Induction of transient third degree atrioventricular block during radiofrequency catheter ablation in a patient with ventricular tachycardia and remote myocardial infarction.

INTRODUCTION: Radiofrequency catheter ablation has been demonstrated to be an effective and safe therapy in patients with so-called idiopathic ventricular tachycardia, whereas the benefit/risk profile for ablation of ventricular tachycardia in patients with chronic myocardial infarction and severely compromised left ventricular function still needs to be determined. The present report describes the unintended induction of transient third-degree atrioventricular block in a patient with remote myocardial infarction who underwent radiofrequency catheter ablation of ventricular tachycardia. METHODS AND RESULTS: Endocardial catheter mapping and radiofrequency ablation were performed in a 57-year-old patient with chronic recurrent ventricular tachycardia, who had previously suffered from anterior and posterior wall myocardial infarction. Additionally, the patient presented with complete right bundle branch block during sinus rhythm. Radiofrequency energy applied to a critical site of the reentrant tachycardia at the left ventricular basal septum during sinus rhythm induced third-degree atrioventricular block after 20 s of current delivery, which lasted for 24 h. At this site, a presumable left bundle branch potential was recorded during sinus rhythm. CONCLUSIONS: Radiofrequency current application for ablation of ventricular tachycardia may induce third-degree atrioventricular block in patients with remote myocardial infarction. When current is delivered to target sites at the left ventricular basal septum, radiofrequency energy should be applied during sinus rhythm to allow continuous monitoring of atrioventricular conduction. Special caution should be given to patients with right bundle branch block during sinus rhythm.

Catheter Ablation↗
PubMed1995

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)

Adult↗
PubMed1995

Successful radiofrequency catheter ablation of right sided accessory pathways during sustained atrial fibrillation.

Up to now there have been no descriptions in the literature of endocardial catheter mapping and successful radiofrequency catheter ablation of the right sided accessory pathway during sustained atrial fibrillation. We attempted ablation of a right posterolateral and a right lateral accessory pathway during sustained atrial fibrillation with rapid anterograde conduction over the accessory pathway in two patients with Wolff-Parkinson-White syndrome. In both patients (aged 47 and 52 years), sustained atrial fibrillation occurred during the electrophysiological study to assess accessory pathway conduction properties. The mean ventricular rate during atrial fibrillation was 180 and 170 beats.min-1, respectively. Both patients were successfully ablated with a single radiofrequency impulse. At the successful ablation sites, a potential of the accessory pathway was consistently recorded preceding the onset of preexcitation in the surface electrogram, by 25 ms in patient 1 and 30 ms in patient 2. The unipolar electrogram recorded from the ablation catheter showed a QS morphology and the accessory pathway potential preceded the intrinsic deflection by 10 ms in both patients. Onset of the ventricular electrogram (patient 1: -20 ms; patient 2: -15 ms) and its activation time (patient 1: -15 ms; patient 2: +5 ms) in relation to the onset of preexcitation in the surface electrocardiogram also indicated the close proximity of the ablation catheter to the accessory pathway. Preexcitation disappeared within 2 s after energy application in both patients. Thus, radiofrequency catheter ablation of right sided accessory pathways during sustained atrial fibrillation is feasible and may obviate the need for medical or electrical cardioversion.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Fibrillation↗
PubMed1995

Comparison of the results of programmed ventricular stimulation from the right ventricular apex and outflow tract: a randomized, prospective study.

OBJECTIVE: The aim of this prospective study was to analyse the yield of programmed ventricular stimulation at the right ventricular apex compared with the outflow tract. METHODS: A stepwise randomized cross-over protocol of programmed ventricular stimulation with alternating stimulation at both sites was used in 66 patients who were studied because of sustained ventricular tachycardia (n = 30), ventricular fibrillation (n = 7), or non-sustained ventricular tachycardia and/or syncope (n = 29). RESULTS: There were no significant differences between the results of stimulation from either right ventricular site with regard to the presence or absence of structural heart disease, spontaneous arrhythmia, ejection fraction or effective refractory periods. Overall, monomorphic ventricular tachycardia was inducible in 33 patients (50%); in 25 patients (75.8%), this arrhythmia was induced from both sites. However, in only 17 of these 25 patients (68%) did the induced monomorphic ventricular tachycardias have the same morphologies and similar (+/- 50 ms) cycle lengths. Ventricular fibrillation was inducible in 11 patients (17%), mostly by three extrastimuli (n = 8; 73%). CONCLUSIONS: (1) stimulation from at least two right ventricular sites is desirable because of their independent contribution to the induction of ventricular tachyarrhythmias, (2) the non-inducibility or inducibility at one ventricular site does not predict the effect at another stimulation site, (3) the effective refractory period at the right ventricular apex and outflow tract do not differ, (4) the inducibility of multiple ventricular tachycardia morphologies emphasizes the importance of documenting the cause of spontaneous arrhythmias with multiple electrocardiographic leads to ensure the correct interpretation of arrhythmias induced by programmed stimulation, (5) clinical or haemodynamic features cannot predict whether one or more stimulation sites will be required for induction of ventricular tachycardia. These results are important for the diagnostic evaluation and assessment of pharmacological or non-pharmacological interventions.

Adolescent↗