Biomedical subjects

J Tebbenjohanns

Publications and source records attributed to J Tebbenjohanns.

At least 37 records · Page 2Linked to original sources

PubMed1998

Acute and long-term effects of consecutive radiofrequency applications on conduction properties of the subeustachian isthmus in type I atrial flutter.

INTRODUCTION: Bidirectional conduction block at the subeustachian isthmus predicts long-term efficacy of atrial flutter ablation. Limited data are available on the incidence and outcome of minor conduction changes such as unidirectional or incomplete block. This prospective study sought to systematically assess discrete acute and long-term alterations of bidirectional conduction prior to a complete conduction block. METHODS AND RESULTS: In 41 patients with type I atrial flutter, pulse propagation through the subeustachian isthmus during low lateral and proximal coronary sinus pacing was documented and analyzed following each consecutive radiofrequency (RF) application. In cases of altered conduction properties and noninducibility of atrial flutter, patients were followed-up for 12 months. Three sets of results were found. First, following RF application, 23 patients presented a progressive conduction delay prior to a complete conduction block. Second, RF application did not always affect counterclockwise and clockwise conduction simultaneously or to the same extent. In 13 patients, an initial alteration of counterclockwise conduction was present before an alteration of clockwise conduction; in 5 patients, clockwise conduction was primarily affected. Third, the recurrence rate of typical atrial flutter was 9% (2/22) in patients with a complete bidirectional conduction block, 54% (7/13) in patients with unidirectional conduction block, and 100% (6/6) in patients with sole bidirectional conduction delay. CONCLUSION: In 50% of the patients, consecutive RF applications resulted primarily in a progressive conduction delay rather than a sudden conduction block. Since counterclockwise and clockwise conduction were not always affected simultaneously or to the same extent, lateral as well as septal pacing is recommended for improvement of bidirectional conduction block. Normalization of primarily altered conduction and, therefore, recurrence of atrial flutter are high in all patients without bidirectional block.

Adult↗

PubMed1997

[10 years radiofrequency ablation of accessory conduction pathways].

Catheter ablation of the preexcitation syndrome is a curative treatment. Accessory pathways between structures of the specific conduction system or working myocardium are morphologic prerequisites for orthodromic or antidromic reentrant tachycardia of various frequency, duration, and rate. Detection of mechanisms of tachyarrhythmias and understanding the role of accessory pathways in tachycardia, mapping of accessory connections, function of nodal conduction system, and additional accessory pathways are necessary for successful catheter ablation. Anomalies of the tricuspid valve and coronary sinus and concomitant disease of the heart should be investigated prior to catheter ablation using echocardiography and contrast injection. Different variations of the preexcitation syndrome and the results of catheter ablation in 300 patients are demonstrated. Catheter ablation is indicated in refractory tachyarrhythmias on the basis of accessory pathways. The treatment is performed in a catheterization laboratory by two highly experienced cardiologists in the field of electrophysiology after training in 100 procedures. The investigators need experience in interventional treatment of coronary artery disease, in transseptal puncture, and in the management of complications (coronary and valvular problems, thromboemboly, and pericardial drainage). Catheterization needs careful protection of radiation. An ablation is possible at an atrial or ventricular insertion site of the accessory pathway or in between. Ablation is done during sinus rhythm, atrial stimulation, antidromic reentry, or atrial fibrillation or during ventricular pacing and orthodromic tachycardia. The procedure should end with bidirectional block of the accessory pathway in 90-95% of the patients. Complications occur in 2-4% of procedures. Recovery of accessory conduction is observed in 8%. Catheter ablation of the accessory pathway is the treatment of first choice in symptomatic patients with the pre-excitation syndrome. The procedure has limited risks and a high success rate.

Cardiac Pacing, Artificial↗

PubMed1997

[Radiofrequency ablation in ventricular extrasystole of the right ventricular outflow tract].

The series of five patients with symptomatic isolated right ventricular outflow tract ectopy and no structural heart disease which were successfully treated with radiofrequency ablation of the ectopic focus are reported in order to discuss radio-frequency ablation as an alternative treatment in patients with right ventricular outflow tract ectopy without ventricular tachycardia.

Cardiac Complexes, Premature↗

PubMed1997

Dose and rate-dependent effects of adenosine on atrial action potential duration in humans.

Adenosine provokes atrial fibrillation (AF) in some patients with paroxysmal supraventricular tachycardia (PSVT). Which patients are more susceptible to develop atrial fibrillation after the administration of adenosine to terminate PSVT is unknown. We prospectively measured atrial action potential duration (APD) at incremental doses of 3, 6, and 12 mg of adenosine at paced cycle lengths (CLs) of 600, 500, and 400 ms in 25 patients. Bolus injection of adenosine decreased APD at 90% repolarization in a dose- and rate-dependent manner. During paced CLs of 600, 500, and 400 ms, decreases of 8%, 13%, and 19% (p < 0.05), respectively, were found after bolus administration of 3 mg of adenosine. After 6 mg of adenosine, the APD shortened by 12%, 19%, (p < 0.05), and 27% (p < 0.01), respectively. After 12 mg of adenosine, the APD shortened by 15%, 27% (p < 0.05), and 38% (p < 0.01), respectively. Transient AF occurred in 4 of 25 (16%) patients, all during paced CLs of 400 ms, and after adenosine 6 mg in one patient and 12 mg in three patients. Adenosine shortens atrial action potential duration in a dose- and rate-dependent manner. Whether patients with faster rates during PSVT and those given higher doses of adenosine are more prone to develop atrial fibrillation remains to be determined.

Action Potentials↗

PubMed1997

Radiofrequency catheter ablation of atrial flutter that elicits inappropriate implantable cardioverter defibrillator discharge.

The case of a patient with recurrent VT and an ICD is reported. After appropriate device discharges, the patient experienced 40 episodes of inappropriate shock therapy due to atrial arrhythmias confirmed as type I atrial flutter. Since programmed stimulation could reliably initiate atrial flutter, catheter ablation was performed. During delivery of RF current, atrial flutter terminated and was no longer inducible. The patient had no further inappropriate device discharges during 12 months of follow-up. In patients with ICDs suffering from recurrences of atrial flutter leading to inappropriate shock therapy, RF catheter ablation is an effective and curative approach.

Atrial Flutter↗

PubMed1996

Nonpharmacologic strategies for treating atrial fibrillation.

Nonpharmacologic tools to treat atrial fibrillation (AF) are direct current cardioversion, radiofrequency (RF) current catheter ablation, antiarrhythmic surgery, pacing, and atrial defibrillation. In patients with sustained AF, when no cause can be found for AF or when the associated disease is mild, an attempt should be made to restore sinus rhythm. Electrical cardioversion by synchronized direct current shock can be attempted when drugs have failed and is the first choice in acutely ill patients. Virtually all patients should be anticoagulated. Temporary pacing should be available in patients with evidence of previous bradycardia. Although efficacy may be improved in patients pretreated with antiarrhythmic drugs, there is a considerable risk of adverse events. In AF and sinus node dysfunction, both pacing and antiarrhythmic drugs may be necessary. Pacing should be atrial or dual chamber, since ventricular pacing provokes AF. Failure to control the ventricular rate in AF can be treated by RF: atrioventricular (AV) node ablation, ablation of accessory pathways in preexcitation syndrome with AF, modulation of AV node, or ablation of AF. Antiarrhythmic surgery is a major procedure and may be the therapy of last resort in AF: the so-called corridor procedure isolates the fibrillating atria from a strip of tissue connecting the sinus and AV nodes. The maze procedure attempts to abolish AF by channeling the atrial activation between a series of incisions. In patients with chronic AF, internal cardioversion should be attempted if conventional transthoracic electrical cardioversion is ineffective. Several studies demonstrated the feasibility and efficacy of internal atrial defibrillation in selected patients with recent onset, as well as with chronic, AF. An implantable atrial defibrillator--as a stand-alone device or as part of a whole heart cardioverter--might be an option in the future. Nonpharmacologic tools play only a minor role in the management of paroxysmal and chronic AF. If symptoms persist despite pharmacologic therapy and other causes of persisting symptoms are excluded, consideration should be given to cardiac pacing, RF catheter treatment, or surgery. in some cases nonpharmacologic therapy of the AV node must be followed by implantation of a permanent pacemaker (due to complete AV block) and anticoagulation (due to persistence of underlying AF.

Adolescent↗

PubMed1996

Direct angiography of the coronary sinus: impact on left posteroseptal accessory pathway ablation.

The purpose of this study was to determine the incidence and types of venous branches and anomalies in posteroseptal accessory pathways (APs) and whether these findings are indicative for successful ablation sites. Some posteroseptal APs may be located epicardially, or may be associated with venous anomalies or related to the middle cardiac vein. These APs account for many of the failures encountered during endocardial ablation. Direct coronary sinus (CS) angiography was performed in 43 consecutive patients with left posteroseptal APs (n = 23) and in 20 patients with AV nodal reentrant tachycardia prior to catheter ablation. In 14 (61%) of 23 APs, a venous branch or an anomaly of the CS was found in the posteroseptal region (6 with middle cardiac vein, 2 with other ventricular venous branches, and 6 had a diverticulum). Eleven (48%) of 23 APs were successfully abolished from within that demonstrated venous system, with a median of four radiofrequency impulses. In the remaining 12 (52%) patients, ablation was attempted from the endocardial site of the mitral annulus. Repeat angiography after energy delivery revealed no major complications in any patient. One (5%) patient with AV nodal reentrant tachycardia had evidence of a CS anomaly (P < 0.01). Various types of venous branches and anomalies are associated with the majority of patients with left posteroseptal APs. The APs are directly related to these complex findings, and AP conduction can easily be eliminated from within the venous branches. CS angiography is suggested prior to catheter ablation of left posteroseptal APs to facilitate the ablation procedure.

Adult↗

PubMed1996

[Exogenous adenosine as an anti-arrhythmia agent].

Adenosine has potent cardiac electrophysiologic effects including a negative chronotropic action on the sinus node and a predominant negative dromotropic action on the AV node. The latter property has mainly led to the use of adenosine as antiarrhythmic agent for the acute management of paroxysmal supraventricular tachycardia (PSVT) mediated by a reentrant mechanism involving the AV node. The effects of adenosine are dose-dependent and of very short duration since the half-life is less than 10s. The efficacy rates for termination of AV reentrant tachycardias were found to be 35% with 3 mg, 60-70% with 6 mg, 80% with 9 mg, and 90-95% with 12 mg adenosine. The AV nodal depressant effects of adenosine have also been used for determining the mechanism of wide QRS tachycardias for differentiating supraventricular tachyarrhythmias with aberrant conduction from ventricular tachycardia. Adenosine either terminates or slows almost all types of supraventricular tachyarrhythmias or it leads to unmasking of the underlying mechanism such as atrial flutter with aberrant conduction. One form of ventricular tachycardia, the idiopathic type originating from the right ventricular outflow tract can usually be terminated with adenosine due to its cAMP-mediated mechanism. Adenosine is helpful to detect or to increase preexcitation which is important for planning a catheter ablation procedure since the preexcitation pattern allows to localize the accessory pathway. Since the action of adenosine usually does not alter the accessory pathway conduction it is also useful for control ablation efficacy noninvasively in terms of antegrade conduction and during ventricular pacing for the retrograde conduction. Further evaluation and research is necessary for better understanding of adenosine action on the human atrial electrophysiology since it provokes atrial fibrillation in some patients, and of adenosine action on the different pathways in AV nodal reentrant tachycardias and some accessory pathways with decremental (AV nodal-like) conduction properties.

Adenosine↗

PubMed1995

[Catheter ablation as an emergency treatment in Wolff-Parkinson-White syndrome with signs of acute infarct].

A 53-year-old man known to have Wolff-Parkinson-White syndrome suffered an acute posterior-wall myocardial infarction. Despite successful thrombolysis treatment with streptokinase he continued to have attacks of supraventricular tachycardia with angina. The ECG showed a short P-R interval and pre-excitation with positive delta waves in leads V1-6, as well as signs of re-infarction. The tachycardias could not be satisfactorily suppressed by drug treatment. Coronary angiography revealed triple vessel disease. During this investigation ventricular extrasystoles occurred which initiated orthodromic supraventricular tachycardia and angina, as well as monophasic S-T elevations in leads II, III and aVF. This provided the indication for immediate high-frequency catheter ablation left laterally at the mitral anulus after a left-lateral accessory conduction pathway had been identified. Three days later the stenoses of the circumflex and anterior interventricular branches were dilated. The patient has been free of symptoms for 3 months and can exercise up to 150 W. The tachycardias have not recurred.

Angina Pectoris↗

PubMed1995

Prospective study of retrograde coronary venography in patients with posteroseptal and left-sided accessory atrioventricular pathways.

The morphologic features of the coronary vein system was prospectively studied with retrograde venography in 117 patients with left-sided (78 patients) and posteroseptal accessory pathway (39). Findings were compared with accessory pathway localization. A mean of 3.3 +/- 1.5 venous branches draining into the coronary sinus or the great cardiac vein could be visualized. The morphologic condition was described and classified. Incidence, morphologic condition, and distribution did not differ between left-sided and posteroseptal accessory pathway. Venous abnormalities including ectasy, diverticulum, narrowing, angulation, and hypoplasia occurred in 22.2%. Diverticulum and narrowing were present in posteroseptal accessory pathway only and always related to the successful ablation site. In patients with left-sided accessory pathway, ectasy, angulation, and hypoplasia were found. Anomalies were less frequent (9% vs 43.6%, p < 0.001) and had no relation to accessory pathway localization. However, the successful ablation site was in 42.3% located < 5 mm to an angiographically visualized venous branch. In conclusion, posteroseptal accessory pathways are often related to coronary sinus abnormalities. In patients with a left-sided accessory pathway venous malformation is uncommon, whereas a close anatomic relation exists between accessory pathway localization and venous ventricular branches.

Adolescent↗

PubMed1995

Changes in the amplitude of endocardial electrograms following defibrillator discharge: comparison of two lead systems.

Changes in the amplitude of endocardial electrograms after an unsuccessful shock attempt have been demonstrated to cause failure of redetection of ventricular fibrillation in patients using an integrated sense-pace defibrillating lead system. Thus, the objective of this study was to compare the effects of defibrillator shocks on the amplitude of endocardial electrograms in 26 patients using two different nonthoracotomy systems, a previous lead (model 0062) or a redesigned version (model 0072). At implant, bipolar endocardial electrograms were obtained before each shock application, during initial detection and redetection of ventricular fibrillation in case the applied shock was unsuccessful, and during intervals of 5, 10, 20, 30, 60, and 120 seconds after each shock delivery. No significant difference was noted in endocardial amplitudes between the lead models 0062 and 0072 during baseline sinus rhythm (12.2 +/- 4.6 mV vs 11.4 +/- 3.8 mV), and during initial ventricular fibrillation (7.0 +/- 2.4 mV vs 7.6 +/- 2.3 mV). During redetection of ventricular fibrillation, however, there was a significant difference (P = 0.0006) in endocardial amplitudes (3.4 +/- 1.9 mV vs 6.6 +/- 2.3 mV) between both leads tested. Comparing lead models 0062 and 0072, marked differences were found in endocardial amplitudes during sinus rhythm 5, 10, and 20 seconds after successful arrhythmia termination: 2.8 +/- 1.9 mV vs 8.6 +/- 2.9 mV (P < 0.0001), 4.6 +/- 2.9 mV vs 9.2 +/- 3.2 mV (P = 0.0007), and 6.4 +/- 4.0 mV vs 10.5 +/- 3.6 mV (P = 0.01). At predischarge testing, failure of redetection of ventricular fibrillation was documented in two patients with the lead model 0062 requiring external defibrillation to restore sinus rhythm. These findings demonstrate a significant less postshock attenuation of the endocardial electrogram amplitudes during persistent ventricular fibrillation after an unsuccessful shock attempt as well as during sinus rhythm immediately following an effective shock delivery using the redesigned lead system model 0072 compared to the electrogram amplitudes obtained in patients using the previous lead model 0062.

Adult↗

PubMed1995

Intravenous adenosine during atrioventricular reentrant tachycardia: induction of atrial fibrillation with rapid conduction over an accessory pathway.

Adenosine is considered to be a safe agent for termination of orthodromic atrioventricular reentrant tachycardia in patients with accessory pathways. A case with initially successful accessory pathway ablation and without preexcitation during sinus rhythm is presented, in which intravenous adenosine (6 mg) during orthodromic tachycardia was followed by atrial fibrillation and sudden onset of preexcitation with subsequent rapid ventricular response with moderate hemodynamic compromise.

Adenosine↗

PubMed1995

Pacemaker function during radiofrequency ablation.

There are increasing numbers of radiofrequency current ablation procedures being reported. Selected patients have antitachycardia or antibradycardia pacemakers. The pacemaker behavior during and after ablation procedures differs widely. We report on the pacemaker reaction of 25 patients with 13 different devices, most with unipolar electrodes. Sensing failures were observed in 8 (32.0%) and pacing failures in 4 (16.0%) patients. Prolonged pauses and induction of tachyarrhythmias were observed. No pacemaker damage was seen although it is reported by other investigators. We recommend deactivation of implanted generators and an external bipolar pacing electrode. Manufacturers should focus their attention on this problem and protect the generators and their functions for 500 kHz radiofrequency current.

Adult↗

PubMed1995

Echocardiographic imaging of coronary sinus diverticula and middle cardiac veins in patients with preexcitation syndrome: impact on radiofrequency catheter ablation of posteroseptal accessory pathways.

To determine the value of echocardiography for identifying coronary sinus (CS) diverticula and middle cardiac veins (MCVs) in patients with posteroseptal accessory pathways (PAPs), transthoracic (TTE) and transesophageal echocardiography (TEE) were performed in 18 consecutive patients with PAP and in 15 control subjects with left lateral accessory pathway before CS angiography. The size, shape, and location of CS diverticula and MCV were described and compared to angiography. TEE and angiography were concordant for the identification of diverticula (n = 5) and agreed for depicting MCV in 22 of the 27 cases. TTE revealed 4 of 5 diverticula and identified 4 of 27 MCV (P < 0.001). Fourteen MCV but no diverticula were found in the control subject. There was no significant difference between transesophageal and angiographic measurements for the width (23.5 +/- 4.9 vs 26.8 +/- 6.6 mm) and height (13.5 +/- 3.8 vs 15.7 +/- 3.4 mm) of the diverticula, and the width (3.5 +/- 0.7 vs 3.7 +/- 0.6 mm) of MCV. TEE underestimated the length of the MCV (12.0 +/- 1.8 vs 27.2 +/- 6.0, P < 0.001). Delivery of radiofrequency energy within the neck of a diverticulum or within an MCV was successful in 5 of 5, and 6 of 13 cases in patients with PAPs, respectively. In conclusion, echocardiography was as reliable as angiography for detecting and describing CS diverticula and MCV in patients with preexcitation syndrome. Echocardiography is recommended prior to electrophysiological study because it may simplify radiofrequency catheter ablation.

Adult↗

PubMed1995

Impact of the local atrial electrogram in AV nodal reentrant tachycardia: ablation versus modification of the slow pathway.

INTRODUCTION: The purpose of this study was to determine the predictors of successful ablation versus modification sites of the slow pathway in patients with AV nodal reentrant tachycardia. Complete elimination of slow pathway conduction ("ablation") is considered to be an appropriate endpoint during radiofrequency (RF) current delivery, whereas the persistence of residual slow pathway conduction with or without single echo beats ("modification") may be indicative of tachycardia recurrence. METHODS AND RESULTS: Of 131 patients, 71 consecutive patients were followed for 15.1 +/- 7.6 months. After elimination of inducible AV nodal reentrant tachycardia in all patients, residual slow pathway conduction (modification) persisted in 38 patients, whereas complete elimination of slow pathway conduction (ablation) was documented in 33 patients. Including electrophysiologic study after 5 to 7 days and after 3 to 6 months, 6 (8.4%) patients had recurrences: 5 with residual slow pathway conduction after the procedure and 1 with complete elimination of slow pathway conduction (P < 0.05). As compared with modulated sites, ablation sites of the slow pathway were characterized as follows: (1) duration of the local atrial electrogram (AEGM) (66.7 +/- 10.2 vs 54.1 +/- 12.6 msec, P < 0.01); (2) interval from the end of the AEGM to onset of His-bundle deflection (4.4 +/- 8.2 vs 16.1 +/- 9.3 msec, P < 0.01); and (3) number of peaks of the AEGM as an indicator of fractionation (4.1 +/- 0.7 vs 3.0 +/- 0.8, P < 0.01). The rate of junctional tachycardias (103.4 +/- 12.1 vs 102.1 +/- 16.9 per min), the AV ratio (0.4 +/- 0.5 vs 0.5 +/- 0.5), the number of RF current deliveries (4.1 +/- 4.4 vs 4.5 +/- 4.4), the duration of the procedure (124.1 +/- 45.3 vs 125.6 +/- 42.3 min), and the fluoroscopy time (15.5 +/- 10.8 vs 16.6 +/- 9.6 min) as well as power and total energy of RF current deliveries and the anatomically calculated catheter position at the successful site were not statistically different. A subset analysis in patients who received only a single RF application showed the same results for both groups. Patients without recurrence (n = 65) were found to have longer duration of the AEGM (61.9 +/- 14.6 msec) and a shorter interval from the end of AEGM to the onset of His-bundle deflection (10.1 +/- 12.2 msec) than patients with recurrence (n = 6) (47.5 +/- 7.5 msec and 20.8 +/- 12.8 msec, respectively). CONCLUSION: Complete ablation of the slow pathway resulted in a lower recurrence rate. The complete ablation approach is feasible using precisely analyzed local AEGMs to guide RF current in AV nodal reentrant tachycardia in a short procedure time.

Adult↗

PubMed1995

Slowing of the ventricular rate during atrial fibrillation by ablation of the slow pathway of AV nodal reentrant tachycardia.

INTRODUCTION: The mechanisms whereby radiofrequency catheter modification of AV nodal conduction slows the ventricular response are not well defined. Whether a successful modification procedure can be achieved by ablating posterior inputs to the AV node or by partial ablation of the compact AV node is unclear. We hypothesized that ablation of the well-defined slow pathway in patients with AV nodal reentrant tachycardia would slow the ventricular response during atrial fibrillation. METHODS AND RESULTS: In 34 patients with dual AV physiology and inducible AV nodal reentrant tachycardia, atrial fibrillation was induced at baseline and immediately after successful slow pathway ablation and at 1-week follow-up. The minimal, maximal, and mean RR intervals during atrial fibrillation increased from 353 +/- 76, 500 +/- 121, and 405 +/- 91 msec to 429 +/- 84 (P < 0.01), 673 +/- 161 (P < 0.01), and 535 +/- 98 msec (P < 0.01), respectively. These effects remained stable during follow-up at 1 week. The AV block cycle length increased from 343 +/- 68 msec to 375 +/- 60 msec (P < 0.05) immediately and to 400 +/- 56 msec (P < 0.01) at 1-week follow-up. The effective refractory period of the AV node prolonged from 282 +/- 83 msec to 312 +/- 89 msec and to 318 +/- 81 msec after 1 week (P < 0.05), respectively. CONCLUSION: This study shows a decrease in ventricular response to pacing-induced atrial fibrillation after ablation of the slow pathway in patients with AV nodal reentrant tachycardia. Since the AV nodal conduction properties could be defined, this study supports the hypothesis that the main mechanism of AV nodal modification in chronic atrial fibrillation is caused by ablation of posterior inputs to the AV node.

Atrial Fibrillation↗

PubMed1995

Radiofrequency catheter ablation of septal accessory pathways.

Catheter ablation of septal accessory pathways in preexcitation syndrome is associated with special problems because of the risk of impairment of atrioventricular nodal conduction during ablation of anteroseptal and midseptal pathways. The complex morphology of the posteroseptal space has special problems for ablation with unclear location of the ablation catheter in the left or right atrial or ventricular cavum, in the coronary sinus, ventricular veins, or the neck of a coronary sinus diverticulum. Therefore, the visualization of the pyramidal space using echocardiographic investigations before the ablation procedure and retrograde coronary sinus phlebography during the ablation session has proven to be very helpful in placement of the electrode to the successful position. Reported herein are the techniques, results, and problems of radiofrequency ablation of 30 patients with septal accessory pathways compared to published data.

Adult↗

PubMed1995

[Extrasystole].

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Cardiac Complexes, Premature↗