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Biomedical subjects

G Hindricks

Publications and source records attributed to G Hindricks.

At least 37 records · Page 2Linked to original sources
PubMed1999

Radiofrequency catheter ablation of accessory pathways. Outcome and use of antiarrhythmic drugs during follow-up.

AIMS: The purpose of this study was to assess the acute and long-term success of accessory pathway ablation in a single large-volume centre, concentrating on long-term recurrences and the clinical use of antiarrhythmic drugs. METHODS AND RESULTS: A total of 519 consecutive patients (mean age 40+/-14 years) underwent radiofrequency ablation of manifest or concealed accessory pathways. The patients were seen in the hospital or by the referring physician at 6 and 12 months. Long-term follow-up information was obtained by questionnaire. Pathway conduction was abolished in 476 cases (91.7%). 'Redo' procedures, due to recurrence, were performed in 38 patients (7.3%) and were successful in 30 (78.9%). Follow-up data were obtained from 454 patients (87.5%) with a follow-up duration of 22. 6+/-12.4 months. Among the 398 patients with successful ablations who responded to the questionnaire, 340 (85.4%) were asymptomatic with only 10.6% taking antiarrhythmic drugs. An additional 20 patients (5.0%) had symptoms suspicious of recurrence. In total, 66 out of 398 successfully treated patients (16.6%) were taking antiarrhythmic drugs. Twenty-three out of 56 (41.1%) patients with failed ablations were asymptomatic, 12 of whom (21.4% of patients with failed ablations) had not been administered antiarrhythmic drugs. In the total group of 454 patients with ablation attempts and available follow-up data, 99 (21.8%) were still taking antiarrhythmic drugs during follow-up. CONCLUSIONS: Patients with successful ablation of accessory pathways show excellent long-term results. However, 17% of successfully treated patients were still taking antiarrhythmic drugs during the period of long-term follow-up. On the other hand, 21% of patients with failed ablations were symptom-free without antiarrhythmic drugs. On an intention-to-treat basis, 22% of the patients with ablation attempts were still taking antiarrhythmic drugs during follow-up.

Adolescent↗
PubMed1999

Catheter ablation of atrial flutter.

Typical atrial flutter in humans is the consequence of a stable macro-reentrant circuit produced by the unique right atrial architecture providing anatomic barriers and functional blocks to conduction. Mapping studies have indicated that the so-called isthmus between the inferior aspect of the tricuspid annulus and the ostium of the inferior caval vein is a critical zone for maintenance of atrial flutter. An anatomically guided approach with placement of a transmural and contiguous lesion line throughout the isthmus has established as curative treatment of typical atrial flutter. Electrophysical criteria indicating complete bidirectional isthmus conduction block after ablation proved to be superior with respect to redurrences of atrial flutter compared with the noninducibility criterion. The gold standard for prove of complete conduction block is the recording of double potentials along the entire isthmus ablation line. Recently, it proved possible to reduce the period of fluoroscopy during isthmus ablation by using electro-anatomical mapping.

Atrial Flutter↗
PubMed1999

Antiarrhythmic surgery for treatment of atrial fibrillation--new concepts.

Curative treatment of atrial fibrillation is one of the main challenges of todays electrophysiology. The ideal treatment strategy should be effective, safe, and easy to apply to allow a widespread use. In addition, curative treatment should not only aim on the restoration of sinus rhythm but also restore mechanical atrial function to improve hemodynamics thereby avoiding anticoagulation. With respect to percutaneous catheter ablation no treatment concept with proven efficiency to cure chronic permanent atrial fibrillation is currently available. Surgical techniques such as the Corridor operation and the left atrial isolation procedure have been shown to effectively store sinus rhythm but these procedures do not restore biatrial transport function. Cox's Maze procedure is highly effective, however, it is an extensive and very time consuming technique which precludes the widespread application of this operation. Thus, new intraoperative treatment concepts are currently under intense clinical investigation. Most new concepts aim on the application of contiguous radiofrequency-induced lesion lines in the atria. Some of the new treatment strategies are based on the replacement of the surgical incisions of the Maze procedure using inrtraoperative radiofrequency coagulation thereby preventing functional determined reentrant circuits. Other new concepts aim on the induction of contiguous atrial lesion lines to eliminate anatomical determined atrial reentrant circuits. The main advantage of these new concepts when compared to the Maze procedure is a significantly shorter treatment time of approximately 20 minutes. In addition, some treatment strategies can also be applied in conjunction with minimally invasive cardiac surgery. The initial results reported with application of new treatment concepts indicate that approximately 60-80% of patients operated on can be cured from atrial fibrillation. Randomised studies with these new treatment strategies are necessary to validate the results and to outline which treatment concept may prove superior to others. Based on the progress made, it can be expected that intraoperative ablation of chronic permanent atrial fibrillation will become an important curative treatment strategy.

Atrial Fibrillation↗
PubMed1999

Intraoperative radiofrequency ablation of chronic atrial fibrillation: a left atrial curative approach by elimination of anatomic "anchor" reentrant circuits.

INTRODUCTION: The percutaneous approach to radiofrequency (RF) catheter ablation for curative treatment of atrial fibrillation (AF) is an investigational technique, and the optimal composition of lesion lines is unknown. We tested an intraoperative RF ablation concept with elimination of left atrial anatomic "anchor" reentrant circuits. METHODS AND RESULTS: In 12 patients with an indication for valve surgery and chronic AF, a right atrial-transseptal approach was chosen for access to the left atrium. AF had been present for 4.3 +/- 3.9 years; the left atria measured 56 +/- 7 mm. Under direct vision, contiguous lesion lines were placed endocardially with temperature-guided RF energy applications for treatment of AF with a specially designed probe. The lesion lines were placed between the mitral annulus and the left lower pulmonary vein, further to the left upper pulmonary vein, from there to the right upper pulmonary vein, and finally to the right lower pulmonary vein. The antiarrhythmic ablation procedure lasted 19 +/- 4 minutes. One patient died postoperatively of low cardiac output. During follow-up of 11 +/- 6 months, chronic AF was ablated successfully in 9 of 11 patients (82%). Six patients were in stable sinus rhythm or intermittent pacemaker rhythm, and three patients were in sinus rhythm with intermittent atypical atrial flutter. CONCLUSIONS: Intraoperative RF energy application for induction of contiguous lesion lines is feasible. Elimination of anatomically defined "anchor" reentrant circuits within the left atrium prevented chronic AF in > 80% of the patients treated. Intraoperative validation of lesion line concepts for curative treatment of AF may be transferred to percutaneous ablation techniques.

Aged↗
PubMed1998

[High frequency current catheter ablation of accessory conduction pathways].

Radiofrequency catheter ablation has established as the first line therapy for the curative treatment of patients with accessory pathway. Atrioventricular accessory pathways irrespective of the exact localisation can be successfully ablated in more than 90% of all cases. Severe complications associated with the ablation procedure are rare and occur in approximately 2% of patients treated. The recurrence rate after successful ablation is approximately 8 to 10%. Recurrence of accessory pathway conduction occurs almost exclusively within the first 3 months following successful ablation, late recurrences are rare. Patients with variants of accessory pathways such as atriofascicular pathways or retrogradely conducting accessory pathways with decremental conduction properties can also be cured with a high success rate. Because of its well balanced efficacy-risk profile radiofrequency catheter ablation should be recommended as the first line therapy to all symptomatic patients with accessory pathway.

Atrioventricular Node↗
PubMed1998

Role of anticoagulant therapy in atrial fibrillation.

Atrial fibrillation belongs to the group of cardiovascular diseases that most frequently predispose to arterial thromboembolic events. Within the last years, the AFASAK, BAATAF, SPAF I, SPINAF, and CAFA trials have consistently demonstrated a significant, approximately 70%, risk reduction for stroke on oral anticoagulation in patients with nonrheumatic atrial fibrillation. This benefit by far outweighed the slight increase in annual major hemorrhage. Recently, additional trials (SPAF II, EAFT, SPAF III, and others) have shed further light on important questions concerning risk factors, secondary prophylaxis, the optimal intensity of anticoagulation, and the role of aspirin and other antiplatelet drugs. The main results of these studies are discussed in this review. The majority of patients with atrial fibrillation are > 65 years of age and have other clinical or echocardiographic risk factors. In these patients, adjusted-dose warfarin with target international normalized ratios (INRs) 2.0 to 3.0 is effective and safe. The risk of stroke rises with INR values < 2.0, whereas INR values > 3.0 result in an increase in intracerebral hemorrhages, especially in the very elderly. In contrast, no anticoagulation seems warranted in younger atrial fibrillation patients < 60 years of age without any clinical or echocardiographic risk factor. An overview of all randomized trials that compared aspirin with placebo and/or adjusted-dose warfarin indicates that adjusted-dose warfarin is approximately 50% more effective than aspirin for primary and secondary prevention of stroke, at least in patients with atrial fibrillation who have clinical risk factors. Therefore, oral anticoagulation clearly is the therapy of choice for prevention of thromboembolism in patients with atrial fibrillation.

Anticoagulants↗
PubMed1997

Antiarrhythmic therapy--future trends and forecast for the 21st century.

This article discusses recent changes in antiarrhythmic therapy, with a focus on nonpharmacologic therapy (electrode catheter ablation, implantable cardioverter-defibrillators [ICDs]), and puts them into perspective for the coming years. The treatment of supraventricular tachycardias and tachycardia involving accessory pathways is likely to remain the domain of catheter ablation. With promising new techniques under investigation, the spectrum of arrhythmias that can be cured will probably be expanded. Treatment of life-threatening ventricular arrhythmias is likely to remain the domain of the ICD in the foreseeable future. With the safety net of the ICD in place, new antiarrhythmic drugs or other forms of antiarrhythmic therapy can be developed and tested.

Anti-Arrhythmia Agents↗
PubMed1997

Subendocardial and intramural temperature response during radiofrequency catheter ablation in chronic myocardial infarction and normal myocardium.

BACKGROUND: The ability of radiofrequency energy to extend across scar tissue is unknown. We investigated the effects of radiofrequency catheter ablation on intramural temperature in experimental chronic myocardial infarction. METHODS AND RESULTS: Myocardial infarction was induced in eight dogs by a transcatheter coronary artery occlusion-reperfusion technique. The dogs were reanesthetized after 15 to 24 days. Four additional dogs served as controls. The freshly excised preparations were cut and placed in a saline bath at 37 degrees C. Temperature-guided energy applications with a preselected catheter tip temperature of 80 degrees C were performed for 60 seconds with a 7F ablation catheter. Thermoelements were inserted into the ventricular muscle at depths of 2.5 to 3.0 mm ("subendocardial") and 5.5 to 6.0 mm ("intramural"). Surviving muscle fibers were interspersed among the transmural scar tissue. The maximal temperatures did not differ significantly between normal hearts and chronic infarctions at the subendocardial (64.5+/-6.4 degrees C versus 66.7+/-6.6 degrees C) or intramural thermo-element (51.9+/-5.7 degrees C versus 52.3+/-5.7 degrees C). The myocardial temperature rise was slow, and steady-state temperatures had not been reached after 60 seconds. The intramural temperatures in chronic infarctions measured 49.0+/-4.3 degrees C after 40 seconds of energy delivery and were still below the critical tissue temperature of 50 degrees C that is necessary to induce permanent myocardial damage. CONCLUSIONS: Temperature-guided radiofrequency ablation in a dog model of chronic myocardial infarction may induce tissue temperatures >50 degrees C at a depth of 5.5 to 6.0 mm. The intramural temperature rise was slow, indicating that long energy applications might be necessary if the arrhythmogenic substrate is subepicardial.

Animals↗
PubMed1997

Radiofrequency catheter ablation of the anterosuperior and posteroinferior atrial approaches to the AV node for treatment of AV nodal reentrant tachycardia: techniques for selective ablation of "fast" and "slow" AV node pathways.

Radiofrequency catheter ablation has been established as a first-line curative treatment modality in patients with symptomatic AV nodal reentrant tachycardia (AVNRT). The successful sites of stepwise catheter ablation approaches of the so-called fast and slow pathways strongly suggest that AVNRT involves the atrial approaches to the AV node. The typical fast pathway ablation sites are located anterosuperior toward the apex of the triangle of Koch, which also contains the compact AV node, whereas the usual slow pathway ablation sites are located posteroinferior toward the base of the triangle of Koch at a greater distance to the compact AV node and bundle of His. Accordingly, ablation studies with large patient cohorts have demonstrated that fast pathway ablation carries a higher risk of inadvertent complete AV block. Thus, the slow pathway is clearly the primary target site, and fast pathway ablation is rarely necessary. Different approaches for slow pathway ablation have been elaborated: anatomically oriented stepwise techniques, ablation guided by double potentials recorded within the area of the slow pathway insertion, and combined techniques. The modern concept of AVNRT suggests that this arrhythmia involves the highly complex three-dimensional nonuniform anisotropic AV junctional area. Accordingly, mapping and ablation studies demonstrated that the anterior approach is not identical with fast pathway ablation, and the posterior approach is not identical with slow pathway ablation. Therefore, it is essential for interventional electrophysiologists to familiarize themselves with the anatomic and electrophysiologic details of this complex and variable specialized AV junctional region. In this review, the anatomic and pathophysiologic aspects of the AV junctional area as they relate to interventional therapy are summarized briefly, and the catheter techniques for ablation of the so-called fast and slow AV nodal pathways for the treatment of AVNRT are described.

Atrioventricular Node↗
PubMed1997

Three-dimensional electromagnetic catheter technology: electroanatomical mapping of the right atrium and ablation of ectopic atrial tachycardia.

INTRODUCTION: The difficult catheter orientation and navigation associated with conventional technology and mono-/multiplane fluoroscopy may complicate ablation procedures of atrial tachycardias. A new three-dimensional catheter technology for electroanatomical mapping of the right atrium and ablation of ectopic atrial tachycardia is described. METHODS AND RESULTS: A novel electromagnetic catheter-based mapping system was investigated for electroanatomical mapping of the entire right atrium in 12 patients. The system reconstructed three-dimensional maps from the multitude of endocardial sites that were sequentially mapped and color coded the individual activation times. The electrophysiologic information was superimposed on the geometry of the mapped area. The anatomical landmarks of the right atrium, i.e., the tricuspid annulus, mouth of the coronary sinus, ostia of the superior and inferior venae cavae, and right atrial appendage, could be depicted in all cases. The sinus node area and the preferential conduction along the crista terminalis could be delineated. In four patients with ectopic atrial tachycardia, the earliest endocardial activation could be identified with high spatial resolution as a "hot spot." After completion of the mapping procedure, the ablation catheter could be reliably renavigated to the site of origin, and ablation was successful with one or two impulses. In one patient with previous atrial septal repair, the activation map allowed the reconstruction of a long line of conduction block induced by the atriotomy. CONCLUSION: Three-dimensional electroanatomical mapping of the right atrium allowed detailed reconstruction of the chamber geometry and activation sequence. The sites of origin of ectopic atrial tachycardias could be identified precisely. The system allowed accurate renavigation to the site of earliest activation, thereby guiding successful ablation of the foci.

Adult↗
PubMed1996

Incidence of complete atrioventricular block following attempted radiofrequency catheter modification of the atrioventricular node in 880 patients. Results of the Multicenter European Radiofrequency Survey (MERFS) The Working Group on Arrhythmias of the European Society of Cardiology.

UNLABELLED: The Multicenter European Radiofrequency Survey (MERFS) retrospectively analysed the incidence of procedure-related complications in 4463 patients who had undergone radiofrequency catheter ablation in 69 European institutions between 1987 and 1992. Of these 4463 patients, 880 underwent modification of the atrioventricular node to cure atrioventricular nodal reentrant tachycardia. This report presents a detailed analysis of the incidence of complete atrioventricular block with respect to the target site and the number of patients reported per institution. The most common complication of modification of the atrioventricular node was the unintended induction of complete atrioventricular block (41 of 880 patients, 4.7%). In 684 of 880 patients (78%), detailed information about the approached target site for modification of the atrioventricular node was available. Complete atrioventricular block occurred significantly more often in patients who underwent ablation of the fast pathway (19/361, 5.3%) or in whom ablation of the slow and fast pathway was attempted after failure at the initial site (4/25, 16%) than in patients who underwent slow pathway ablation (6/298, 2.0%, P < 0.05). The overall incidence of complete atrioventricular block was significantly higher (6.3%) in centres with limited experience in radiofrequency modification of the atrioventricular node ( < or = 30 patients treated; group I: n = 526) compared to centres that had treated > 30 patients (group II: n = 354; 2.3%; P < 0.05). In addition, in those patients in whom the target site was available, the incidence of complete atrioventricular block after fast pathway ablation was significantly higher in group I (n = 168 patients) when compared to group II (n = 193 patients) (7.7% vs 3.1%, P < 0.05) and also tended to be higher after slow pathway ablation in group I (2.4% in group I vs 1.5% in group II; P = ns). CONCLUSIONS: In this analysis of collaborative data, radiofrequency catheter modification of the atrioventricular node carried a risk of approximately 5% of complete atrioventricular block. The incidence of complete atrioventricular block was significantly higher in patients who underwent fast pathway ablation or fast and slow pathway ablation after failure at the initial site compared with slow pathway ablation. In addition, the results indicate that there is a learning curve, regarding the incidence of complete atrioventricular block, which is a significant complication of the procedure, when modifying the atrioventricular node. Thus, caution is recommended when performing radiofrequency modification of the atrioventricular node using the so-called anterior approach to abolish fast pathway conduction, especially when the experience of the institution or investigator/s is limited.

Atrioventricular Node↗
PubMed1996

Temperature-controlled radiofrequency catheter ablation of manifest accessory pathways.

OBJECTIVES: The primary objectives of this study were to assess the feasibility of temperature-controlled radiofrequency catheter ablation of left and right sided manifest accessory pathways in patients with Wolff-Parkinson-White syndrome and to gain more insights into biophysical aspects of temperature-controlled catheter ablation in humans. BACKGROUND: The electrode-tissue interface temperature and other biophysical parameters are among important variables determining the efficacy and safety of radiofrequency ablation of accessory pathways. Experimental studies have shown that radiofrequency-induced tissue necrosis can be accurately predicted by monitoring of catheter tip temperature. METHODS: 38 consecutive patients (14 f, 24 m; aged 42 +/- 12 years) with anterograde conducting accessory pathways (left sided: n = 22; right sided: n = 16) underwent temperature-controlled radiofrequency ablation (HAT 200S, Dr Osypka, Germany). The electrode temperature was monitored via a thermistor embedded into a 4 mm catheter tip. Power output was adjusted automatically during energy delivery in a closed loop system (preselected temp.: 70.1 +/- 5.8 degrees C). RESULTS: Accessory pathway conduction was successfully abolished in all patients after the delivery of 2.3 +/- 2.1 radiofrequency pulses (range: 1-9, median: 2). Interruption of the accessory pathway as evidenced by loss of preexcitation occurred after 5.9 +/- 5.4 s. At the time of the interruption of the accessory pathway the catheter tip temperature measured 54.2 +/- 11.2 degrees C in patients with left and 44.9 +/- 5.0 degrees C in patients with right sided accessory pathways, respectively (P < 0.008). Higher temperature levels during left sided applications did not shorten the time it took for the effect to appear (left sided accessory pathway: 7.5 +/- 6.3 s, right sided accessory pathway: 3.7 +/- 2.9 s; ns). The catheter tip temperature was significantly higher during left compared to right sided applications after 5 (52.1 +/- 3.1 degrees C vs 47.2 +/- 4.3 degrees C) and 10 s (61.5 +/- 6.2 degrees C vs 52.7 +/- 4.2 degrees C) following initiation of the impulse (P < 0.005). Power output and delivered energy did not differ significantly at the time of accessory pathway abolition. Peak values of delivered power (45.1 +/- 10.9 W vs 41.3 +/- 10.6 W; P < 0.05) and total delivered energy (2452 +/- 1335 J vs 1392 +/- 762 J; P < 0.02) were significantly higher in the group of right sided pathways compared to left sided applications. The peak temperature measured 77.1 +/- 13 degrees C during effective and 69.9 +/- 14 degrees C during ineffective energy applications (P < 0.05). The time it took for the effect to appear was significantly longer in transiently effective pulses (10.4 +/- 7.2 s) compared to permanently effective applications (5.9 +/- 5.4 s; P < 0.02). Despite temperature control, an abrupt rise in impedance was observed in 10 of 89 (11%) energy applications. No procedure-related complications occurred. CONCLUSIONS: Temperature-controlled radiofrequency ablation of manifest accessory pathways is highly effective and safe. The temperature response is faster and significantly higher in left-sided energy applications compared to right-sided pulses. Peak temperature levels measured at the electrode tip are significantly higher during effective than ineffective pulses. Sudden rises in impedance are not completely prevented during temperature-controlled radiofrequency ablation of accessory pathway, although no procedure-related complications were noted in this patient cohort.

Adult↗
PubMed1996

Temperature-controlled slow pathway ablation for treatment of atrioventricular nodal reentrant tachycardia using a combined anatomical and electrogram guided strategy.

AIMS: Anatomical and electrogram-guided techniques have been used separately for slow pathway ablation in atrioventricular nodal reentrant tachycardia. The aims of the present study were to analyse electrogram characteristics of target sites and biophysical parameters using a combined anatomical and electrogram-guided technique for temperature-controlled radiofrequency catheter ablation of the slow pathway. METHODS AND RESULTS: Using a temperature-controlled (pre-selected 60 degrees C) catheter system, 53 patients with atrioventricular nodal reentrant tachycardia underwent slow pathway radiofrequency ablation. Mapping was started posteroseptally near the coronary sinus ostium and continued towards the midseptal area if needed. The longest and latest atrial electrograms with an atrioventricular ratio of < or = 0.5 were targeted. After a median of two pulses (mean 2.36 +/- 1.33), atrioventricular nodal reentrant tachycardia was rendered non-inducible in all patients without complications. Successful sites had longer atrial electrograms (78.8 +/- 9.8 vs 67.6 +/- 13.3 ms, P < 0.003) and larger ventricular electrogram amplitudes (92.4 +/- 51.2 vs 63.1 +/- 28.8 mV, P < 0.05) than the failed sites, but had a similar atrioventricular ratio, P-A interval and atrial electrogram amplitude. Overall, an atrial electrogram duration of > or = 70 ms was associated with effective radiofrequency delivery, with 86% sensitivity and 62% specificity. The achieved temperature maximum was 62.3 +/- 9.8 degrees C at successful and 58.8 +/- 9.0 degrees C at unsuccessful sites (ns). There was no significant difference between successful and unsuccessful applications with respect to power output, impedance and total delivery energy. During a pre-discharge study, three patients with inducible atrioventricular nodal reentrant tachycardia underwent a repeat ablation. During 12.3 +/- 2.5 (6-15) months of follow-up, three others had a clinical recurrence of atrioventricular nodal reentrant tachycardia. CONCLUSIONS: The combined approach for slow pathway ablation is highly effective, requiring a low number of radiofrequency pulses. Long atrial activation time seems to be the most powerful predictor of success. Similar catheter tip temperature levels during successful and unsuccessful radiofrequency applications indicate that suboptimal selection of target sites rather than ineffective heating due to poor catheter tissue coupling is responsible for unsuccessful energy delivery.

Adolescent↗
PubMed1996

Variants of preexcitation--specialized atriofascicular pathways, nodofascicular pathways, and fasciculoventricular pathways: electrophysiologic findings and target sites for radiofrequency catheter ablation.

INTRODUCTION: In the present report, the electrophysiologic findings in patients with different types of variants of preexcitation, i.e., atriofascicular, nodofascicular, and fasciculoventricular fibers, and the results of radiofrequency catheter ablation using different target sites are described. METHODS AND RESULTS: Twelve patients (mean age 36 +/- 17 years) with variants of the preexcitation syndromes underwent electrophysiologic study and radiofrequency catheter ablation. The atrial origin of atriofascicular pathways remote from the normal AV node was assessed by application of late atrial extrastimuli that advanced ("reset") the timing of the next QRS complex without anterograde penetration into the AV node. In patients with atriofascicular pathways, ablation of the accessory pathway or the retrograde fast AV node pathway was attempted. Ablation of the atriofascicular pathways was guided by a stimulus-delta wave interval mapping in the first five patients and by recording of atriofascicular pathway activation potentials in the next five patients. A nodofascicular pathway was suggested if VA dissociation occurred during tachycardia and if atrial extrastimuli failed to reset the tachycardia without anterograde penetration into the AV node. A fasciculoventricular connection was suggested if the proximal insertion of the accessory pathway was found to arise from the His bundle or bundle branches. The PR interval was expected within normal limits during sinus rhythm and the QRS complex to be slightly prolonged with a discrete slurring of the R wave, suggesting a small delta wave. Ten of the 12 patients had evidence for atriofascicular pathways and one patient each for a nodofascicular and fasciculoventricular pathway. In six patients, the atriofascicular pathways were successfully ablated, and in two patients, the retrograde fast AV node pathway. In one patient, a concealed right posteroseptal accessory AV pathway served as the retrograde limb and was successfully ablated. The nodofascicular pathway was shown to be a bystander during AV node reentrant tachycardia. After successful fast AV node pathway ablation resulting in marked PR prolongation, no preexcitation was present during sinus rhythm because of the proximal insertion of the nodofascicular pathway distal to the delay producing parts of the AV node. The proximal insertion of the fasciculoventricular pathway was suggested to arise distal to the AV node at the site of the penetrating AV bundle. The earliest ventricular activation at the His-bundle recording site indicated the ventricular insertion of this accessory connection into the ventricular summit. The fasciculoventricular connection gave rise to a fixed ventricular preexcitation and served as a bystander during orthodromic AV reentrant tachycardia incorporating a left-sided accessory AV pathway. CONCLUSION: The majority of patients with variants of the preexcitation syndrome present with specialized atriofascicular pathways that seem to originate from remnants of the specialized AV ring tissue. Nodofascicular and fasciculoventricular pathways exist and may give rise to preexcitation, although their functional role in participation of clinical arrhythmias still needs to be elucidated. In the present study, both a fasciculoventricular pathway and a nodofascicular pathway acted as a bystander.

Adolescent↗
PubMed1996

[Methods of catheter ablation in ventricular tachycardic arrhythmias].

Catheter ablation has evolved as the therapy of choice in patients with atrioventricular nodal reentrant tachycardia or atrioventricular tachycardia involving accessory pathways. Radiofrequency current catheter ablation is now generally accepted and most frequently used. In patients with ventricular tachycardia and no organic heart disease (idiopathic ventricular tachycardia) the success rates range between 80-90%. In addition, in patients with bundle branch reentrant tachycardia up to 100% success rates are described. The usefulness of radiofrequency ablation in patients with structural heart disease is still controversial. Although in patients with incessant ventricular tachycardia high acute success rates are observed, the results in post-myocardial infarction tachycardia or dilative cardiomyopathy range only between 40 and 75%. Further refinement of localization techniques as well as improvement of ablation technology is mandatory until the routine use of this technique as a curative procedure for ventricular tachycardia is defined.

Atrioventricular Node↗
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↗