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Background: The COVID-19 pandemic necessitated a time-critical expansion of medical staff in intensive care units (ICU) and emergency rooms (ER)., Objective: This article describes the development, performance and first results of an interprofessional blended learning concept called hospital paramedics, qualifying paramedics and additional medical personnel to support ICUs and ERs., Material and Methods: The Protestant Hospital of the Bethel Foundation (EvKB), University Hospital OWL, University of Bielefeld in cooperation with the Study Institute Westfalen-Lippe, developed a 2-stage blended learning concept (stage 1 e‑learning with online tutorials, stage 2 practical deployment) comprising 3 modules: ICU, ER and in-hospital emergency medicine. At the beginning, the participants were asked about their sociodemographic data (age, gender, type of medical qualifications) and subjective feeling of confidence. At the end, a final discussion with the participant, the practice instructor and the supervising physician took place and an evaluation of the deployment by the head of the practice and the hospital paramedic was carried out using questionnaires., Results: Within 6 weeks 58 (63%) of the 92 participants completed the online course and 17 (29%) additionally completed their traineeship. In the ICU they assisted with preparing catheter systems, medication and nursing, performed Manchester triage and initial care in the ER. After completion hospital paramedics were significantly more confident when working in a hospital, catheterization and tracheostoma care (p < 0.05). Of the supervisors 94% deemed the deployment as useful and 100% of the participants were prepared to be available at short notice in their areas as compensation for the COVID-19-pandemic in the event of a staff shortage. Through the provision of additional intensive care ventilators and monitoring units in the period from March to the beginning of May 2020 and the personnel management that was carried out, the EvKB was in a position to increase the number of previously provided ventilator beds by potentially >40 ventilation places., Conclusion: Blended learning concepts, such as hospital paramedics, can quickly qualify medical personnel for use in system-relevant settings, relieve nursing staff and thus create an expansion of intensive care capacities. Existing or pending pandemic and contingency plans should be complemented by such blended learning training so that they are immediately available in case of a second pandemic wave, future pandemics or other crisis situations.

Antiarrhythmic drugs are used in at least 50% of patients who received an implantable cardioverter defibrillator (ICD). The potential indications for antiarrhythmic drug treatments in patients with an ICD are generally the following: reduction of the number of ventricular tachycardias (VTs) or episodes of ventricular fibrillation and therefore reduction of the number of ICD therapies, most importantly, the number of disabling ICD shocks. Accordingly, the quality of life should be improved and the battery life of the ICD extended. Moreover, antiarrhythmic drugs have the potential to increase the tachycardia cycle length to allow termination of VTs by antitachycardia pacing and reduction of the number of syncopes. In addition, supraventricular arrhythmias can be prevented or their rate controlled. Recently published or reported trials have shown the efficacy of amiodarone, sotalol and azimilide to significantly reduce the number of appropriate and inappropriate ICD shocks in patients with structural heart disease. However, the use of antiarrhythmic drugs may also have adverse effects: an increase in the defibrillation threshold, an excessive increase in the VT cycle length leading to detection failure. In this situation and when antiarrhythmic drugs are ineffective or have to be stopped because of serious side effects, catheter ablation of both monomorphic stable and pleomorphic and/or unstable VTs using modern electroanatomic mapping systems should be considered. The choice of antiarrhythmic drug treatment and the need for catheter ablation in ICD patients with frequent VTs should be individually tailored to specific clinical and electrophysiological features including the frequency, the rate, and the clinical presentation of the ventricular arrhythmia. Although VT mapping and ablation is becoming increasingly practical and efficacious, ablation of VT is mostly done as an adjunctive therapy in patients with structural heart disease and ICD experiencing multiple shocks, because the recurrence and especially the occurrence of "new" VTs after primarily successful ablation with time and disease progression have precluded a widespread use of catheter ablation as primary treatment.

The purpose of an electrophysiological study is to verify the mechanism of arrhythmias and to decide the means of therapy for the clinical arrhythmia (pharmacological, radiofrequency catheter ablation, pacemaker-, ICD-implantation). The electrode catheters are introduced percutaneously into the right atrium, to the His-bundle, into the coronary sinus and/or into the right ventricle. By this electrode catheters the intracardiac electrograms are registered and programmed stimulation of the heart is performed. The electrical conduction properties are analysed. With stimulation manoeuvres most of the clinical tachycardias can be induced. In the first part of this overview we describe the procedure of an electrophysiological study, in the second part the indications are discussed.

Within the past 20 years, refinements in electrophysiologic mapping techniques have provided a better understanding of the pathophysiology of atrial flutter and atrial fibrillation (AF), which resulted in the development of catheter ablation techniques for this arrhythmias. Nowadays, catheter ablation has become the first line treatment of recurrent symptomatic or hemodynamically significant atrial flutter. In contrast, catheter ablation of AF is still an investigational procedure and should be restricted to patients with symptomatic AF who have been refractory to multiple antiarrhythmic drugs. In symptomatic patients with AF and an uncontrolled ventricular rate who have failed treatment with several antiarrhythmic drugs and who do not fit for primary catheter ablation of AF atrioventricular junction ablation with prior pacemaker implantation is recommended.

Atrial fibrillation is the most frequent sustained arrhythmia, especially in the elderly. Atrial fibrillation often is precipitated by underlying cardiac or noncardiac disease, but it may also occur as 'lone atrial fibrillation'. Hemodynamic impairment and thromboembolic events are leading to an important morbidity, mortality and health costs. This review-article describes the actual management of this common arrhythmia.

Atrial fibrillation in patients with isolated, therapy resistant, chronic or paroxysmal atrial fibrillation (AF) or AF in combination with additional valvular and non-valvular cardiac pathology can be surgically treated by different techniques. Unipolar high frequency, cryotherapy and microwave energy is a curative approach for the treatment of the left atrium for AF. The postoperative mortality and morbidity rate is comparable to other cardiac surgery procedures. It is a technically less challenging procedure as compared to the MAZE procedure and can be applied using a minimally invasive approach. Alternative techniques such as new cryotechnologies, laser application and bipolar high frequency energy need to be evaluated for effectiveness and safety.

We report 3 adolescents with structurally normal heart who were referred to hospital due to long-lasting palpitations. Initial 12-lead-ECG showed sustained, monomorphic ventricular tachycardia, right bundle branch block QRS morphology and axis deviation. After failure of different anti-arrhythmic drugs finally the intravenous medication with verapamil led to termination of ventricular tachycardia in all three patients. All clinical findings and the responsiveness to verapamil are consistent with the diagnosis of idiopathic left ventricular tachycardia. In one patient an electrophysiological study was done and increased left ventricular vulnerability was shown. After inducing a tachycardia originating from the left ventricle radiofrequency catheter ablation of the left-posterior fascicle was successfully performed. The tachycardia was not inducible after this ablation. Since that investigation the patient has been asymptomatic without anti-arrhythmic treatment. Two of three patients have been on oral verapamil prophylactically and have been free of symptoms.

History: While cycling a 38-year-old man suddenly experienced palpitations associated with marked weakness. 90 min later his general practitioner, having diagnosed a ventricular tachycardia (VT) with a rate of 218/min, terminated it by a drug injection., Investigations: Electrocardiography (ECG), echocardiography and biventricular cardiac catheterization with right ventricular contrast injection failed to provide any evidence of structural abnormality. However, ergometry and EPS with programmed ventricular stimulation induced VT of identical morphology (left bundle branch bloc [LBBB] with right axis deviation [RAD])., Treatment and Course: Idiopathic right-ventricular outflow tract tachycardia (IRVT) having been diagnosed, the patient was put on a maintenance dose of 50 mg/d atenolol. After 6 months without symptoms he again experienced several attacks of tachycardia. Resting ECG merely revealed an epsilon potential and negative T waves in V1-V3. Right ventricular contrast injection revealed inferolateral dyskinesia. EPS demonstrated both the known VT and a second, morphologically different one (LBBB with LAD). These findings indicated arrhythmogenic right-ventricular cardiomyopathy (ARCV). A cardioverter/defibrillator was implanted (ICD) and over the subsequent 8 months he had six episodes of VT which were quickly terminated by the ICD., Conclusion: At first presentation of right-ventricular outflow tract tachycardia it is often not possible to differentiate between IRVT and arrhythmogenic RV cardiomyopathy. The two being significantly different in prognosis and treatment, follow-up monitoring is essential to establish the definitive diagnosis.

Radiofrequency catheter ablation has established as the first line therapy for the curative treatment of patients with accessory pathways. For left-sided accessory pathways, the retrograde approach over the aortic valve is commonly used for ablation of the ventricular insertion. For right-sided and septal accessory pathways, the atrial insertion is usually approached from the right atrium. Atrioventricular accessory pathways irrespective of the exact localization can be successfully ablated in more than 90-95% of all cases. Severe complications associated with the ablation procedure are rare and occur in approximately 2-3% of patients treated. The recurrence rate after successful ablation is approximately 5-10%. Recurrences of accessory pathway conduction occur almost exclusively within the first 3 months following successful ablation whereas late recurrences are rare. Because of the favorable efficacy--risk profile, radiofrequency catheter ablation can be recommended as the first line therapy to all symptomatic patients with accessory atrioventricular pathways.

Radiofrequency catheter ablation has established itself as a first line therapy for the curative treatment of many patients with supraventricular or atrioventricular tachycardias and also for selected types of ventricular tachycardia. The success rates of catheter ablation of various types of cardiac arrhythmias are impressively high. Procedure related complications can be attributed to the invasive nature of the technique (e.g., bleeding or other vascular complications, radiation exposure) but may also occur as a specific complication related to the type of intervention performed (e.g., complete AV-block following attempted modification of the AV-node). In patients undergoing radiofrequency ablation procedures, radiation exposure carries a small but measurable risk of malignancy and hereditary disorders. The risk of fatal malignancy has been calculated to be approximately 1/1000 per hour of fluoroscopy and the risk of significant hereditary disorders approximately 10 per 1 million live births per hour fluoroscopy time. However, it is important to realize that these risks are age and sex dependent being higher in young and/or female patients. For the physician performing catheter ablation procedures no significant risks related to fluoroscopy exposure may be expected as long as all established tools for protection are used. Based on the results of large single center studies and multicenter investigations, complications during or after radiofrequency catheter ablation of supraventricular or atrioventricular arrhythmias may occur in 4-5% of cases. Severe complications (life threatening or permanently disabling complications) may occur in approximately 1-2% of patients treated. In patients undergoing ablation of ventricular tachycardia, a higher incidence of total procedure related complications between 5-7% and severe complications (3-4%) may be expected. The higher incidence of complications in patients with ventricular tachycardia when compared to catheter ablation of supraventricular or atrioventricular tachycardia may be explained by the fact that many patients with ventricular tachycardia suffer from severe cardiovascular disease.

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.

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.

Since its introduction into clinical practice in 1982, catheter ablation has evolved as a first-line mode of non-pharmacological therapy in patients with atrioventricular nodal reentrant tachycardia and in patients with atrioventricular tachycardia involving an accessory pathway. The initial experience was based on the use of direct current for ablative purposes. However, since severe complications have been observed using this energy source, radiofrequency (RF) current catheter ablation is now the most frequently used technique. Efficacy rates are high (> 80%) in patients with idiopathic ventricular tachycardia and bundle-branch reentrant tachycardia. In addition, the technique also has a relatively high acute success-rate in patients with incessant ventricular tachycardia. However, RF current catheter ablation is less effective in patients with drug-resistant, chronic, sustained ventricular tachycardia after myocardial infarction or in the presence of dilated cardiomyopathy. Further improvements which include new criteria for the localization of the origin of ventricular tachycardia as well as technical improvements are particularly needed in this subgroup of patients. Thus, RF current catheter ablation in patients with ventricular tachycardia can be considered a promising new mode of non-pharmacological therapy. The efficacy rate of the procedure is highly dependent on the presence and type of organic heart disease as well as the mechanisms underlying ventricular tachycardia. Due to the limited experience, especially with respect to the long-term results, RF current catheter ablation is still an experimental mode of antiarrhythmic treatment.

So-called "Mahaim-pathways" represent a distinct subset of accessory pathways and the preexcitation syndromes with unique electrophysiologic properties. During sinus rhythm, preexcitation is minimal or absent whereas incremental atrial stimulation reveals preexcitation with a left bundle branch block like morphology. "Mahaim-fibers" exhibit long conduction times, decremental conduction properties by atrial extrastimuli or incremental atrial pacing, and conduction only in the anterograde direction. The typical atrioventricular reentrant tachycardia incorporating a "Mahaim-pathway" is a preexcited antidromic tachycardia with anterograde conduction over the accessory pathway and retrograde conduction over the AV node. "Mahaim-fibers" may be associated with dual AV node physiology or common atrioventricular accessory pathways. The original concept of "Mahaim-fibers" consisted of accessory pathways originating in the AV node and inserting into the distal right bundle branch ("nodofascicular" pathways) or the right ventricle ("nodoventricular" pathways). This understanding has been challenged by surgical interventions identifying the atrial insertion of "Mahaim-pathways" at the parietal tricuspid annulus. Later, electrophysiologic and surgical studies have confirmed the antero-to posterolateral atrial origin of these accessory pathways remote from the atrioventricular node. Therefore, the concept of nodoventricular pathways has been replaced by the concept of atriofascicular pathways. Recently, endocardial catheter mapping and radiofrequency catheter ablation have substantially contributed to the characterization of this unusual form of the preexcitation syndrome. Distinct, high-frequency activation potentials of atriofascicular accessory pathways can be recorded at the atrial insertion at the antero- to posterolateral tricuspid annulus and along the entire ventricular course up to the ventricular insertion in the right ventricular apical region near or at the distal right bundle branch. The long conduction times and the decremental conduction properties result from a delay in the interval from the local atrial activation at the atrial insertion to the activation potential of the accessory pathway whereas the conduction time between the activation potential of the accessory pathway and the local activation at the ventricular insertion is relatively constant. Overall, the current knowledge about atriofascicular pathways is indicative of a proximal AV-node-like component and a distal bundle-branch-like component and, therefore, suggestive of an accessory AV conduction system. Radiofrequency current application for ablation of atriofascicular pathways can be accomplished at their atrial insertion and along their entire ventricular course. Highfrequency activation potentials of the atriofascicular pathways identify target sites for ablation. Transient mechanical conduction block by catheter manipulation at the subannular level of the atrial insertion has also been introduced as a marker for successful ablation of these unusual accessory pathways.

Radiofrequency catheter ablation has been established as a first line therapy for the curative treatment of patients with atrioventricular nodal reentrant tachycardia and atrioventricular tachycardia encompassing accessory pathways as well as for ablation of the "normal" AV-junction. For these indications, the success rates exceed 90%. Acute complications during ablation of accessory pathway and ablation of the "normal" AV-junction occur in approximately 2-5% of patients treated. The incidence of complications during modification of the atrioventricular node to cure AV-nodal reentrant tachycardias clearly depends on the ablation technique used. The anterior approach with ablation of the so-called "fast pathway" carries a significantly higher risk of complete AV-block when compared to the inferior approach (so-called "slow pathway ablation") (approximately 4-8% vs. 2%). Arrhythmia recurrence after successful ablation of the "normal" AV-junction occurs only rarely, while the recurrence rate after modification of the AV-node or ablation of accessory pathway is approximately 10% during long-term follow-up. Recently, it has been shown that other, rare types of supraventricular tachycardia (sinus-atrial reentrant tachycardia, ectopic atrial tachycardia, human type I atrial flutter) can also be successfully ablated using radiofrequency current. In addition, first clinical results indicate that modification of anterograde AV-nodal conduction properties in patients with atrial fibrillation and fast ventricular rate by radiofrequency application to postero- and midseptal sites might be a useful therapeutic tool to slow ventricular rate. Because of the high success-rate and the relative low incidence of severe procedure related complications, the indications of radiofrequency ablation procedures for the treatment of supraventricular tachycardias will be extended in the future. In addition, it might be reasonable to expect that during the next years, all types of supraventricular tachycardia, except atrial fibrillation, can be targeted and cured by radiofrequency ablation in the majority of cases.

Radiofrequency catheter ablation has become an established treatment modality for definite cure of patients with WPW-syndrome or concealed accessory pathways. On-line monitoring of the induced tissue effects plays an important role concerning the efficacy and safety of this procedure. In a 50 year-old man with recurrent atrioventricular tachycardia, endocardial catheter mapping revealed a left anterolateral concealed accessory pathway. A temperature-guided radiofrequency pulse with a preselected temperature of 70 degrees C was applied during tachycardia when stability of the local electrogram, continuous ventriculoatrial activity during orthodromic tachycardia, and registration of a Kent-potential indicated electrogram criteria for a successful ablation. However, orthodromic tachycardia did not terminate, and catheter tip temperature only reached a plateau of 45 degrees C with maximal power output of 50 watts indicating an insufficient catheter tip-tissue-contact. Therefore, the bending of the catheter curve was slightly straightened during energy application without pushing the catheter forward in order to achieve a better tip electrode contact with the tissue. Simultaneously, a sudden increase in catheter tip temperature was observed accompanied by termination of the tachycardia indicative of the successful ablation of the accessory pathway. At present, a control of radiofrequency catheter induced tissue effects can be best achieved by temperature-guided energy application whereas monitoring of current, voltage, and impedance are insufficient in this respect. In the present case, correction of the catheter placement during energy application could be achieved because of the on-line monitoring of the catheter tip temperature thereby allowing successful ablation of the accessory pathway with a single radiofrequency pulse.

AV-nodal reentrant tachycardia (AVNRT) is a common cause of recurrent supraventricular tachycardia. Currently, catheter ablation of either slow or fast pathway are nonpharmacologic options for the treatment of patients with AVNRT. Radiofrequency (RF) catheter ablation of the fast pathway was attempted in 35 patients (aged 46.7 +/- 15 years; 12 m, 23 f) with recurrent AVNRT. RF energy (25-50 watt, 30-90 s) was delivered to the anterior right atrial septum. The catheter was placed posterior to the largest His bundle deflection. AV conduction was monitored during continuous pacing of the high right atrium while the RF current was applied. RF-ablation was acutely successful using a mean of 6.5 +/- 6.2 impulses in 31 patients. Late spontaneous block of the slow pathway occurred in one patient (pat. 17) with an unsuccessful initial attempt of fast pathway ablation. PQ and AH interval increased significantly after the ablation procedure (PQ: from 149 +/- 27 to 208 +/- 34 ms, AH: from 76 +/- 22 to 131 +/- 38 ms; p value: < 0.0001). Acute interruption of retrograde VA conduction was the result in 23 patients. Six patients (17%) had a recurrence of AVNRT during a follow-up period of 11.9 +/- 7.5 months. Five of 6 patients underwent a second successful procedure. Complete AV block occurred in 3 of the first 10 consecutive patients and in none of the subsequent 25 patients (overall incidence: 8.6%). Thus, RF ablation of the fast retrograde pathway is an effective method for the curative treatment of AVNRT.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial fibrillation is frequently initiated during radiofrequency catheter ablation of accessory pathways. It has been generally believed that initiation of atrial fibrillation may complicate the localization of accessory pathway. Therefore, most centers currently perform cardioversion in order to continue the ablation session. The purpose of the present study was to assess the feasibility and the electrophysiologic criteria for successful radiofrequency catheter ablation of left sided accessory pathways during atrial fibrillation in patients with WPW-syndrome. Radiofrequency ablation was performed in 87 patients with left-sided manifest accessory pathways during atrial fibrillation (n = 16) or during sinus rhythm (n = 71). The criteria for localization of accessory pathways were recording of stable accessory pathway potentials, local ventricular activation preceding the onset of the intrinsic flection of the unipolar electrogram and a QS pattern of the unipolar electrogram. Overall, the accessory pathways were successfully interrupted in 85/87 patients (98%). During the first ablation procedure, abolishing of accessory pathways was achieved in 15 of 16 patients (94%) during atrial fibrillation compared to 64 of 71 patients (90%) during sinus rhythm (n.s.). The total procedure time and fluoro time was significantly shorter during atrial fibrillation than during sinus rhythm (161 +/- 91 min vs. 216 +/- 128 min, p < 0.05, and 31 +/- 24 vs. 41 +/- 26 min. p < 0.05, respectively). Thus, it is feasible and very effective to perform radiofrequency ablation of left-sided manifest accessory pathways during atrial fibrillation. Precise localization of accessory pathway during atrial fibrillation seems even easier than during sinus rhythm as indicated by shorter procedure and fluoro times in the atrial fibrillation group.

The prevalence of atrial fibrillation increases with age, with rates of 2-5% among people over the age of 60 years. Patients may be highly symptomatic or may suffer from hemodynamic compromise or thromboembolic complications. However, antiarrhythmic drug treatment implies problems like the choice of the suitable drug, the individual benefit/risk profile, and alternative treatment strategies. Experimental and clinical data support the concept that atrial fibrillation in the clinical setting in most cases is due to multiple reentrant wavelets. A critical number of three to six simultaneously circulating reentrant wavelets seems to be necessary for the maintenance of atrial fibrillation. Consequently, antiarrhythmic drugs may terminate or prevent atrial fibrillation by prolonging the refractory period or slowing conduction velocity, thereby leading to conduction block. In clinical practice, antiarrhythmic therapy may act by slowing of the ventricular rate due to depression of atrioventricular nodal conduction or by termination and/or prevention of atrial fibrillation. Digitalis is commonly used for the control of the ventricular rate. Betablocking drugs and verapamil are effective in this respect during exercise performance. For antiarrhythmic conversion and prophylaxis of recurrences of atrial fibrillation, class Ia (e.g., quinidine), Ic (e.g., flecainide and propafenone), and class III (e.g., amiodarone and sotalol) drugs of the Vaughan Williams classification are useful. Presently, no general concept exists whether medical or electrical cardioversion should be used as a first line approach for termination of atrial fibrillation. In the individual patient with atrial fibrillation, the potential benefit of restoring sinus rhythm must be weighed against the morbidity and mortality of the arrhythmia and the morbidity and mortality of the antiarrhythmic agents used.(ABSTRACT TRUNCATED AT 250 WORDS)

Proarrhythmia is defined as the provocation of new cardiac arrhythmias or the aggravation of preexisting arrhythmias by antiarrhythmic drugs. The possible types of manifestation of proarrhythmia are manifold. With respect to prognosis, drug-induced ventricular tachyarrhythmias seem to be of particular importance. Monomorphic ventricular tachycardia and ventricular tachycardias of the torsade de pointes type have to be distinguished. The former seem to be mainly based on reentrant mechanisms, while the later is supposed to result from triggered activity. Drug-induced monomorphic tachycardia is most often observed during therapy with drugs which slow conduction (class I agents, proarrhythmic potency: IC > IA > IB). Patients with depressed left ventricular function and previously documented life-threatening tachyarrhythmias are the most susceptible candidates. Torsade de pointes can be preferentially observed during therapy with antiarrhythmic drugs which prolong myocardial repolarization (i.e. class IA and class III agents). Electrolyte abnormalities and/or bradycardia are factors which often predispose to the development of this particular type of proarrhythmia. The physician who prescribes antiarrhythmic drugs must be aware of the different types and clinical manifestations of proarrhythmia. This is necessary to assess the degree of proarrhythmic risk and to determine the benefit/risk ratio before the start of drug therapy.

In many patients with paroxysmal or chronic atrial fibrillation, long-term antiarrhythmic drug therapy is performed to prevent recurrences of atrial fibrillation or to reduce the incidence of paroxysmal attacks of atrial fibrillation. The results of several studies on the efficacy of antiarrhythmic drugs in patients with paroxysmal atrial fibrillation have revealed that the incidence of recurrent attacks of atrial fibrillation can be reduced and the duration of arrhythmia free intervals can be prolonged by antiarrhythmic drug therapy. However, complete prevention of atrial fibrillation can be achieved only in a minority of patients. At present, there is no evidence that antiarrhythmic drug treatment of patients with paroxysmal atrial fibrillation might worsen the prognosis by an increase in cardiac mortality induced by antiarrhythmic drugs. In patients with chronic atrial fibrillation, the recurrence rate of the arrhythmia can be significantly reduced by antiarrhythmic drug therapy within the first year of treatment. However, there is evidence that antiarrhythmic drugs might worsen the prognosis when compared to patients with atrial fibrillation not treated with antiarrhythmic drugs. Accordingly, the indication for antiarrhythmic drug therapy to prevent recurrences in patients with chronic atrial fibrillation has to be made restrictively and should be largely based on the symptomatic status of the patients. Antiarrhythmic drug therapy seems to be indicated only in patients who are significantly symptomatic or compromised by the arrhythmia. In patients without or with only mild symptoms, medical therapy with the aim to slow the ventricular response with digitalis, calcium antagonists or betablocking agents seems to be more adequate. Currently, with respect to efficacy and safety, there is no antiarrhythmic drug that has been proved to be superior to others and that can thus be recommended as the drug of first choice for patients with paroxysmal or chronic atrial fibrillation to prevent recurrences. The choice of the optimal antiarrhythmic drug should be made by taking individual factors (e.g., etiology of the arrhythmia, patient compliance, liver and renal function of the patient, additional medical therapy) into account. Major problems during long-term antiarrhythmic drug therapy may arise in patients with pre-existing sinus node dysfunction or conduction disturbances of the atrioventricular node. In addition, the conversion of atrial fibrillation with relatively slow ventricular rates to the atrial flutter with fast ventricular rates that is occasionally observed during treatment with class I-antiarrhythmic drugs may complicate long-term therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Torsade de pointes (TDP) is a polymorphic ventricular tachycardia with a particular electrocardiographic pattern of continuously changing ("twisting") morphology of the QRS complex occurring in the setting of delayed myocardial repolarization (i.e., prolongation of the QT interval). TDP may develop in the setting of an idiopathic disorder (Jervell/Lange-Nielsen syndrome, Romano-Ward syndrome, sporadic long QT syndrome) or may be induced by pharmacologic agents which prolong the QT interval, as well as by other clinical circumstances under which repolarization is delayed (e.g., hypokalemia, hypomagnesemia, bradycardia) (acquired long QT syndrome). Since the treatment of TDP strongly differs from that of conventional ventricular tachycardia, correct diagnosis is critical as it guides the treating physician in selecting the appropriate mode of therapy. In this paper mainly the electrocardiographic criteria presently used for the correct identification of this unusual form of ventricular arrhythmia are presented. Additionally, the potential mechanisms and therapeutic modalities of TDP are discussed.

Oral anticoagulation in patients with rheumatic heart disease for prevention of systemic thromboembolism is accepted clinical practice. The incidence of stroke in patients with nonrheumatic atrial fibrillation is about five times the rate of patients in sinus rhythm. However, contradictory findings in several small retrospective studies have precluded determination of a gold standard for patients with nonrheumatic atrial fibrillation so far. Recently, the results of five prospective, placebo-controlled studies in patients with nonrheumatic atrial fibrillation treated with anticoagulation have been published. A consistent risk reduction of thromboembolism ranging from 37 to 87% in patients treated with warfarin was reported. This risk reduction occurred in excess of a relatively low incidence of intracerebral and/or fatal bleeding complications. The efficacy of prevention of thromboembolism was comparable for high intensity anticoagulation (International Normalized Ratio (INR) 2.8-4.2) and low dose anticoagulation (INR 1.5-2.7). However, fatal and/or intracerebral bleedings only occurred with INR > or = 2.6. In subgroup analysis, recent congestive heart failure, arterial hypertension, and previous apoplex or arterial thromboembolism were independent clinical predictors of increased risk for thromboembolism, whereas results in patients with chronic and intermittent atrial fibrillation were comparable. In 69 patients with lone atrial fibrillation, no single event occurred in the follow-up period. Thus, lone atrial fibrillation does not seem to carry an increased risk for stroke when strict criteria for diagnosis of lone atrial fibrillation are applied. In two of the five studies, aspirin was additionally randomized. Since contradictory findings resulted, the role of aspirin for prophylaxis of stroke still needs to be determined.(ABSTRACT TRUNCATED AT 250 WORDS)

The underlying mechanism of most ventricular tachycardias in the setting of chronic myocardial infarction is reentrant excitation. At that time, the active membrane properties like upstroke velocity and amplitude of action potentials of muscle fibers surviving in the border zone of the infarction have returned nearly completely to normal. Anisotropic conduction characteristics, however, importantly contribute to the electrophysiologic properties of the epicardial and/or endocardial border zones in chronic myocardial infarction. In normal myocardial tissue with tight coupling between muscle fibers, conduction velocity is slower for impulses propagating transverse to fiber orientation compared to longitudinal to fiber orientation due to a higher effective axial resistivity ("uniform" anisotropy). With infarct healing, connective tissue invading into the epicardial border zone separates surviving muscle fiber bundles and thereby decreases cell-to-cell coupling ("non-uniform" anisotropy). In this setting, excitation waves propagate transverse to fiber orientation in an irregular sequence and conduction velocity in this direction is significantly reduced without occurrence of acute ischemia. Block of conduction waves propagating longitudinally to fiber orientation may lead to activation of the area distal to the block with long delay by very slow transverse wavefronts. This long delay allows fibers proximal to the line of block to regenerate excitability, and reentrant excitation may be initiated. The common pathway of figure-eight tachycardias preferentially orientates longitudinally to fiber orientation. Very slow conduction transverse to fiber orientation at the pivoting points of reentrant circuits may lead to the occurrence of excitable gaps.

Unlabelled: To determine the effects and the underlying mechanisms of sudden rise of impedance during radiofrequency (RF) catheter ablation, 60 RF applications were delivered to isolated preparations of ventricular myocardium at three different power levels (mean: 3.7, 11.3, 19.3 watts). Pulse duration was 30 s, current voltage and catheter tip temperature were continuously monitored. Impedance rise occurred during 34 of 60 applications; the incidence of impedance rise increased at higher power levels. Impedance rise was significantly more often observed when the preparations were superfused with heparinized blood compared to saline solution (p less than 0.05). Catheter-tip temperature during radiofrequency application without impedance rise was significantly lower compared to applications with impedance rise (mean = 108 degrees C vs. 121 degrees C, p less than 0.01). The increase of catheter-tip temperature and maximal-tip temperature following impedance rise was significantly higher in blood when compared to saline solution (mean = +48 degrees C vs. +13 degrees C (p less than 0.001), Tmax: 121 degrees C vs. 245 degrees C). Following impedance rise, insulation defects of the electrode catheter and vaporized crater formation of the myocardium was often observed., Conclusions: During radiofrequency catheter ablation impedance rise occurs following overheating of the catheter electrode (greater than 110 degrees C). After impedance rise, catheter-tip temperature markedly increases. Insulation defects of the catheter and vaporized craters in the myocardium frequently occur after impedance rise. The results have important implications for the clinical use of RF-currents for catheter ablation; energy application should be immediately stopped after the occurrence of impedance rise.

Left-atrial myxomas produce a broad array of clinical symptoms depending on their location, size, and morphology. The clinical presentation is characterized by obstruction of blood flow, systemic embolism, and unspecific systemic effects. Within 6 weeks, three patients presented in our clinic with left-atrial myxomas. Primary differential diagnoses were infective endocarditis, circulatory collapse, and transient ischemic attack of unknown origin. In all cases diagnosis was made with echocardiography (m-mode, 2D, TEE). In this review the etiology, epidemiology, and pathology are reported briefly. The variety of clinical symptoms with the corresponding differential diagnosis is presented systematically and discussed with our patients. Diagnostic, therapeutic, and prognostic aspects are summarized.