Interactive In-Vitro Training In Physics Of Radiofrequency Ablation For Physicians And Medical Engineering Students.

Radiofrequency (RF) ablation requires a complex set of devices as well as profound electrophysiological experience and substantial knowledge of physical science basics. To establish RF ablation in-vitro teaching-system, six workstations were equipped with computer-controlled RF ablation generators. Universal connection boxes allow ablation-essays with catheters of different make and model. Special wetlabs were developed combining a basin containing isotonic saline solution with a thermostat and a pump to simulate blood flow. This hands-on teaching system can be used to demonstrate differences in lesion-forming dependent on tip-electrodes, sensor technology and ablation techniques, influence of blood flow and electrode-angle to the myocardium. It was also utilized to reproduce industrial in-vitro tests.

Concealed accessory pathways: Historical notes.

Concealment of an accessory pathway is caused by its ability to conduct retrogradely only. This variant of accessory pathway conduction could not be confirmed until invasive electrophysiology was introduced in the 1970s. As a rule, it is reported that concealed accessory pathways were predicted from animal experiments in 1971. However, even earlier studies suggested an accessory pathway or mechanisms comparable to those of the Wolff-Parkinson-White syndrome to be the cause of supraventricular tachycardias even though preexcitation during sinus rhythm had been lacking. Such interpretations were derived from clinical considerations, from patients having lost their ventricular preexcitation spontaneously, and from the disappearance of the delta wave after drug administration. Some authors postulated but did not provide the correct interpretation. Even a few contributions published before the paper of Wolff, Parkinson, and White in 1930 are worth considering in this context.

[CRT in atrial fibrillation--methodical and apparatus options in decision-making]. / CRT bei Vorhofflimmern. Methodische und apparative Optionen zur Entscheidungsfindung.

Heart failure and atrial fibrillation often coexist, especially with increasing degree of heart failure severity. Under this constellation, the advantage of cardiac resynchronization therapy (CRT) is still under discussion and displayed as an unresolved problem in the guidelines for cardiac stimulation and resynchronization. If ventricular desynchronization can be documented and response to CRT can be expected, the challenge is to interoperatively seek the best left ventricular electrode position and to postoperatively optimize the device in order to achieve the best therapy performance. This situation encourages the development of individualized methods and to utilize innovative apparatus features in order to consolidate individual decisions and to optimize CRT in heart failure with atrial fibrillation.

[Left ventricular electromechanical latency period is an additional indicator to upgrade from right to biventricular DDD pacing]. / Die linksventrikuläre elektromechanische Latenzzeit ist ein zusätzlicher Indikator für ein Upgrading zur biventrikulären Stimulation.

In DDD pacing, the left-ventricular electromechanical latency period defines the duration between premature ventricular stimulation and the prematurely ending left-atrial contribution to left-ventricular filling. It has to be considered in diastolic AV delay optimization. Individual duration of this parameter seemed to reflect the ventricular function. Therefore, we compared the left-ventricular electromechanical latency period due to right ventricular stimulus with the documented ejection fraction of two groups, 33 congestive heart failure patients carrying biventricular systems and 13 right ventricular paced bradycardia patients. A mean latency period of 168+/-26 ms was found in the heart failure patients (ejection fraction: 25+/-5%) which was significantly longer (p=0.0039) compared to the bradycardia patients (ejection fraction: 51+/-12%) with a mean latency of 119+/-13 ms. Thus, an increasing latency period during right ventricular DDD pacing therapy indicates decreasing ejection fraction. A cut-off interval of 135 ms allowed the discrimination of 93% of our patients as having an individual ejection fraction of either up to 35% or above. Thus, the left ventricular electromechanical latency period can be used as an additional parameter indicating the necessity to upgrade from right to biventricular DDD pacing.

[Feasibility and safety of long-term AAI(R) pacing in isolated sinus node syndrome]. / Realisierbarkeit und Sicherheit einer alleinigen AAI(R)-Schrittmacherbehandlung beim isolierten symptomatischen Sinusknotensyndrom.

Recent investigations prove that AAI(R) pacing is the "ideal" stimulation mode in isolated sick sinus syndrome. Nevertheless, in Germany this bradycardia is treated by AAI(R) pacemakers in less than 4% of cases compared to 25% in other countries. In our institution treatment of patients with isolated sick sinus syndrome is uniform and corresponds to the actual guidelines since the early 1990s; therefore the aim of our study was to analyze feasibility and safety of AAI(R) pacing in a retrospective study. Between 1998 and 2000, 52 of 165 patients (31.5%) with isolated sick sinus syndrome were treated by an AAI(R) pacemaker. The median follow-up duration was 51.5 months (minimal: 36 months). 6 patients died, in all cases unrelated to the stimulation mode. Three patients required reoperations, however, in only one case due to second degree AV block with the need for upgrading to DDD stimulation. Thus, the yearly incidence of this specific complication in the AAI(R) cohort is 0.64%.In conclusion, permanent atrial stimulation in isolated sick sinus syndrome is feasible in a quarter of all cases. It is safe if performed corresponding to actual guidelines. Additionally, single lead AAI(R) pacing is a cost-effective therapy and the only stimulation mode which, today, reliably prevents unnecessary right ventricular stimulation. If, on the other hand, algorithms providing automatic mode switching from AAI to DDD and vice versa are implemented reliably into all dual chamber pacemakers, single chamber atrial pacing will no longer be a subject for discussion.

Bendamustine, vincristine and prednisone (BOP) versus cyclophosphamide, vincristine and prednisone (COP) in advanced indolent non-Hodgkin's lymphoma and mantle cell lymphoma: results of a randomised phase III trial (OSHO# 19).

PURPOSE: The purpose of this study was to compare the efficacy and toxicity of bendamustine, vincristine + prednisone (BOP) with a standard regimen of cyclophosphamide, vincristine + prednisone (COP) in patients with previously untreated advanced indolent non-Hodgkin's lymphoma (NHL) and mantle cell lymphoma. METHODS: A total of 164 patients with follicular lymphoma (grade 1/2), mantle cell lymphoma or lymphoplasmacytic lymphoma (immunocytoma) was randomised to treatment with vincristine 2 mg (day 1) and prednisone 100 mg/m2 (days 1-5) + bendamustine 60 mg/m2 (days 1-5) or + cyclophosphamide 400 mg/m2 (days 1-5) for a total of eight 21-day cycles. RESULTS: The rate of complete remission was 22% with BOP and 20% with COP. The projected 5-year survival rate was 61% with BOP and 46% with COP. The BOP-associated 5-year survival advantage almost reached significance in the subgroup of patients who responded to therapy (74% vs. 56%; P = 0.05), and did reach significance in responders who did not receive interferon maintenance therapy (70% vs. 47%; P = 0.03). Toxicity was acceptable in both treatment groups, although alopecia and leucopenia were more severe with COP. CONCLUSIONS: Bendamustine can efficaciously and safely replace cyclophosphamide, as used in standard COP therapy, for the treatment of patients with indolent NHL and mantle cell lymphoma. Long-term survival data suggest a clinically significant benefit for patients treated with BOP.

[Acute thrombosis of pelvic and leg veins in agenesis of the renal segment of the inferior vena cava]. / Akute Becken-Beinvenenthrombose bei Agenesie des renalen Segments der Vena cava inferior.

A 19-year-old, otherwise asymptomatic man presented to the hospital of orthopaedic surgery with acute severe pain like lumbago. Symptomatic treatment was performed after extensive orthopaedic diagnostic procedures. On the third day after admission he showed clinical signs of deep vein thrombosis with painful swelling and livid discoloration of both legs. Colour duplex ultrasound revealed complete thrombosis of the leg and pelvic veins bilaterally, but the cranial extent was not clear. Contrast-enhanced helical computer tomography of the abdomen and the pelvis confirmed deep pelvic vein thrombosis and showed extension into the inferior vena cava. Moreover, the study revealed the agenesis of the renal segment of the inferior vena cava with collateral flow through dilated lumbar veins to enlarged azygous and hemiazygous, through vertebral and paravertebral venous plexus. The renals were drained via dilated capsular veins. The agenesis of renal vena cava is a very rare anomaly causing acute thrombosis of the deep leg and pelvic veins. Other risk factors of thromboembolic disease were not found. The patient was treated successfully with systemic thrombolysis. Therefore we used ultra-high streptokinase infusion (9 million units over 6 hours). Colour duplex ultrasound revealed good flow into deep leg and pelvic veins after three cycle of lysis. Magnetic resonance angiography of the abdomen and pelvis was performed to evaluate the successful fibrinolysis with complete recanalisation of the pelvic veins and to demonstrate the venous anatomy. Permanent oral anticoagulation with phenprocoumon is indicated to decrease the high rate of recurrent thrombosis. Compression stockings were prescribed. To prevent thrombosis, additional risk factors like smoking, immobilization and unusual physical activity should be strictly avoided.

[Perforated mitral valve aneurysm as a rare course of bacterial endocarditis]. / Perforiertes Mitralklappenaneurysma als seltene Verlaufsform einer bakteriellen Endokarditis.

A 65 year old man with a history of mechanical aortic valve replacement acquired Enterococcus faecalis mediated infective endocarditis about 3 years later. Transesophageal echocardiography revealed formation of an aneurysm confined to the anterior mitral valve leaflet. The aortic valve revealed no signs of endocarditis by transesophageal ultrasound. With sudden perforation of the mitral valve aneurysm, subsequent hemodynamic deterioration and pulmonary oedema, the patient underwent emergency mitral and aortic valve replacement. The postoperative course was uneventful.

What range of programmable AV delays is necessary in antibradycardia DDD stimulation?

DDD pacemakers differ considerably in device specific extents of AV delay (AVD) programmability. To demonstrate the requirements of a mean DDD pacemaker patient population optimal AVDs in 200 DDD pacemaker patients (age 8 to 91 years) were estimated by left atrial electrography. The results should help to define an AVD programmability standard. Left atrial electrograms were recorded via a bipolar filtered esophageal lead. The method aims on adjusting the left atrial electrogram to 70 ms prior to the ventricular spike, both during VDD and DDD operation of the pacemaker. In atrial sensed stimulation the optimal AVD varied from 40 to 205 ms (100.5 +/- 24.5 ms) and in atrial paced stimulation from 85 to 245 ms (169.1 +/- 24.5 ms). The difference of the mean values is statistically significant (p < 0.001). The difference between both values in the individual patient, the individual AVD correction time, varied from 0 to 170 ms (68.7 +/- 26.6 ms). Thus, from our findings requirements on AV delay programmability standard can be derived: AVDs (1) should have a range from 40 to 250 ms, (2) should be independently programmable during atrial sensed and atrial paced operation, and (3) should provide as nominal settings 100 ms for atrial sensed and 170 ms for atrial paced stimulation.

[Selection of the optimal pacemaker - Are age and secondary disease related health conditions significant?]. / Indikationsgerechte Wahl des Schrittmachers - Welche Bedeutung haben durch Alter und Zweitleiden bedingte Zustände?

UNLABELLED: In pacemaker statistics a dichotomy exists between the theoretically possible and the actually implanted number of physiological pacemakers. Hence, the aim of the study was to investigate the influences of age and non rhythm related health conditions on the selection of the pacemaker system.In 468 pacemaker patients the arguments for mode selection at first implantation were listed prospectively during a period of 3 years and 9 months. Mode selection followed electrocardiographic (recommendations of the German working Group on Cardiac Pacing), clinical (incidence of only intermittent bradycardias, stage of the underlying cardiac or of a second noncardiac disease) and sociomedical (non rhythm related general heath condition) aspects. Regarding the ECG findings physiological pacing was possible in 329 cases. Nevertheless, 57 of them (17.3%) received a VVI(R) system. Analysis of the reasoning leading to this dicision demonstrated that age-related problems and non-rhythm-caused health conditions became superior instead of rhythmologic aspects in 1.0% of all patients (pts) under 70, in 2.7% of all pts between 70 and 79, and in 10.8% of all pts 80 or more years of age. CONCLUSIONS: Beyond the age of 80 years, in about 11% of the pts who need a pacemaker, non-rhythm-related clinical and sociomedical aspects gain priority over the electrophysiologic defect. Thus, complete coincidence of the theoretically possible and the actually implanted number of physiological pacemakers in this age group cannot be attained. Regarding all factors influencing the selection of the pacemaker system 45 to 55% are more realistic.

Exercise induced sympathetic influences do not change interatrial conduction times in VDD and DDD pacing.

Using telemetry, right atrial electrogram (RA), and marker channel of atrial sense events (MA) in combination with the left atrial electrogram (LA), recorded by a filtered bipolar esophageal lead, interatrial conduction during submaximal exercise and at rest was examined in 46 DDD pacemaker patients. The RA-LA and MA-LA conduction times measured in the presence of atrial sensing (VDD) as well as the conduction time SA-LA from atrial stimulus (SA) to LA, determined during atrial pacing (DDD) were found to be individual constants independent of exercise induced sympathetic influences. Thus, having determined an optimal mechanical interval (LA-LV)mech/opt from left atrium to ventricle by other methods, the optimal AV delay for DDD as well as for VDD operation can be calculated by the sum of the appropriate interatrial conduction time (SA-LA, respectively MA-LA) and the (LA-LV)mech/opt interval. Due to the constant SA-LA and MA-LA, the difference between these two values (AV delay correction interval) is a constant as well, which remains unchanged during exercise. Therefore, in selecting the rate responsive AV delay, only hemodynamic and not electrophysiological measurements need to be considered.

Orthodromic and antidromic pacemaker circus movement tachycardia.

Pacemaker circus movement tachycardia (PCMT) during DDD pacing is usually sustained by retrograde natural and antegrade electronic atrioventricular (AV) conduction. As PCMT is often initiated by a ventricular premature beat (VPB) one method of its prevention is the programming of an atrial stimulus synchronously following a ventricular extrasystole. A patient is described with preserved antegrade, but without retrograde, i.e., VA, conduction. The optional pacemaker mode of synchronous atrial stimulation following a VPB caused an unusual PCMT sustained by retrograde electronic and antegrade natural AV conduction. This PCMT is similar to a natural reentry tachycardia, the most common variety of which (based on retrograde conduction) is termed antidromic and that which we describe is orthodromic.

[Significance of modern therapeutic procedures in long-term treatment of supraventricular tachyarrhythmias]. / Zur Bedeutung der modernen Therapieverfahren bei der Langzeitbehandlung supraventrikulärer Tacharrhythmien.

To get a quantitative statement concerning the significance of modern therapy in supraventricular tachyarrhythmias 200 consecutive patients who were admitted to a coronary unit were analysed retrospectively. Finally accepted treatment were empirical drug therapy in 85 per cent, electrophysiologically controlled medical treatment in 12.5 per cent, pacemaker therapy in 1 per cent, and ablative procedures (catheter ablation and surgical Kent bundle dissection) in 2.5 per cent. As strictly atrial tachyarrhythmias are prevailing and advantages of electrophysiologically controlled drug therapy are not proven, in the majority of cases of supraventricular tachyarrhythmias empirical medical treatment is sufficient. Only in very few cases it is surpassed by the modern procedures. But, nevertheless these modern methods should be known to find the best treatment in problematical cases.