Georg Heinrich von Knorre

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 optima! 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 electrophysiologica] measurements need to be considered.

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, ami (3) should provide as nominal settings 100 ms for atrial sensed and 170 ms for atrial paced stimulation.

A historical perspective of pacemaker infections: 40-years single-centre experience.

AIMS The approach to infected cardiac devices has changed during recent decades. Optimal treatment is still a matter of debate, especially in pacemaker-dependent patients. Therefore, we investigated the management and outcome of patients with pacemaker infections in a single centre over four decades. METHODS AND RESULTS We conducted a retrospective analysis of 4212 patients and extracted those with pacemaker infections admitted to Rostock Heart Center between 1973 and 2012. One hundred and thirty-one consecutive patients (median age 69.6 ± 14.9 years) were admitted for device infections. Two-stage exchange was performed in 42 patients (32.8%). In 72 patients (55%), explantation and implantation on the contralateral side was performed simultaneously. In 17 cases the device was not replaced. Mean follow-up was 63 ± 81 months. Reinfection rate was 12.2%, which declined from 24% (1980s) to 2.6% (after 2000). Complete device removal (in 57.3%) reduced the risk for reinfection by 75% (P = 0.02), as well as increasing age (0.049% per year, P = 0.001). One-stage exchange increased the risk of reinfection six-fold (P = 0.021). Cultured bacteria after initiation of antibiotic therapy predicted a four-fold increase in risk of a recurrent infection (P = 0.01). CONCLUSION Continuous assimilation of guidelines for pacemaker infection improved the outcome over time: complete extraction of the infected device seems to be highly desirable. A one-stage exchange increased the risk of recurrent device infection and should probably be avoided, but complete extraction seems to be more important than timing.

The earliest published electrocardiogram showing ventricular preexcitation.

When in 1930, Wolff, Parkinson, and White published what is today known as the WPW, or preexcitation syndrome, they, and subsequently others, found few comparable cases in the preceding literature. Among these the report of Cohn and Fraser, published in 1913, was the earliest. However, another even earlier documentation in a 1909 article by Hoffmann escaped notice till now. The ECG of a patient with paroxysmal tachycardia reveals a short PR interval and a delta‐wave‐induced widening of the QRS complex, even though the reproduced tachycardia was not preexcitation related. The interpretation of this poorly reproduced ECG can be confirmed by another and more detailed description of the patient in an electrocardiography textbook published in 1914 by the same author. Thus, the earliest publication of an ECG showing ventricular preexcitation now can be dated back to 1909. Moreover, the Hoffmann monograph contains two additional examples of the WPW syndrome not noticed until now. All three cases published by Hoffmann had their first ECG recordings in 1912 or earlier.

Approximation des individuell optimalen AV-Delays mittels linksatrialer Elektrokardiographie

SummaryFrom a hemodynamic point of view, the AV delay is optimal when the end of the left atrial electro-mechanical action and the beginning of left ventricular contraction coincide. Synchronous recordings of the esophageal electrogram during pulsed-wave Doppler mitral inflow AV delay optimization have shown that a mean interval LA-SV between the left atrial deflection LA in the esophageal electrogram and the ventricular stimulus SV of 69.9 ± 18.6 ms achieves this synchronicity during both DDD and VDD operation. Using this result as a representative mean value in patients with AV block and normal ventricular function, the individual optimal AV delay during resting conditions can be approximated, calculating the optimal AV delay by the actual programed AV delay and the individual measured deviation of the actual LA-SV interval from 70 ms. Using additional hardware, this simplified and quick method can be performed using different standard pacemaker programmers. It was implemented into the Biotronik PMS 1000 programmer software.ZusammenfassungAus hämodynamischer Sicht ist das AV-Delay optimal, wenn das Ende der linksatrialen elektromechanischen Aktion mit dem Beginn des linksventrikulären Druckanstiegs koinzidiert. Synchronregistrierungen einer gefilterten bipolaren Ösophagusableitung während Dopplersonographischer AV-Delay-Optimierungen ergaben bei Patienten mit AV-Block für das Intervall LA-SV zwischen der linksatrialen Deflektion LA in der Ösophagusableitung und dem ventrikulären Stimulus SV für VDD- und DDD-Stimulation einen Mittelwert von 69,9 ± 18,6 ms. Wird entsprechend diesem Ergebnis 70 ms als repräsentativer Wert angesehen, lässt sich bei Patienten mit AV-Block und normaler Ventrikelfunktion ein angenähert individuell optimales AV-Delay bestimmen, indem unter dem jeweils programmierten AV-Delay die Abweichung des aktuellen LA-SV von 70ms gemessen wird. Mit zusätzlicher Hardware ist diese vereinfachte Methode mit einer Reihe von Programmmiergeräten durchführbar. Sie wurde als Software in den Programmer Biotronik PMS 1000 implementiert.

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.

Optimale Platzierung der Vorhofelektrode

SummaryBackgroundDiscussion of right atrial electrode position in dual chamber pacemaker therapy has electrophysiologic and hemodynamic aspects. While electrophysiologic aspects helped to develop several concepts of an electrophysiologically optimal atrial electrode position in atrial fibrillation preventing stimulation, the question for a hemodynamically optimal atrial electrode position is unanswered.Aim and methodsKnown facts (our own results and findings from the literature) concerning hemodynamic consequences of different atrial electrode positions are discussed.ResultsCompared with sinus rhythm, routinely used auricular or lateral atrial electrode positions in dual chamber pacemaker therapy cause a delayed left atrial depolarization und contraction. This electrical and mechanical delay is significantly shortened by right atrial septal pacing. Despite this, effects on cardiac output by atrial electrode position are less convincing.ConclusionsWhile electrode position causing interindividual differences in interatrial relations have to be taken into consideration in hemodynamically individual pacemaker programming, a hemodynamically optimal right atrial electrode position with actual and additional hemodynamic consequences does not exist.ZusammenfassungHintergrundEine Betrachtung der optimalen Platzierung der Vorhofelektrode im Rahmen der Therapie mit 2-Kammerschrittmachern kann unter elektrophysiologischen oder hämodynamischen Gesichtspunkten erfolgen. Während elektrophysiologische Aspekte bereits zu Konzepten einer elektrophysiologisch optimalen Platzierung der Elektrode für die präventive Stimulation beim paroxysmalen Vorhof.immern geführt haben, ist die Frage nach einer hämodynamisch optimalen Lage der Vorhofelektrode noch offen.Ziel und MethodeDiskussion der zum Thema der hämodynamischen Bedeutung aus Literatur und eigenen Untersuchungen bekannten Fakten.ErgebnisseIm Vergleich zum Sinusrhythmus führt eine routinemäßig über das rechte Herzohr oder die freie Wand des rechten Vorhofs durchgeführte atriale Stimulation im Rahmen einer 2-Kammerschrittmachertherapie zu einer verzögerten Depolarisation und Kontraktion des linken Vorhofs. Diese Verzögerung wird durch eine rechtsseptale Reizung signifikant reduziert. Dennoch sind Effekte am Herzauswurf in Abhängigkeit von der Elektrodenlage weniger deutlich erkennbar.SchlussfolgerungenWährend elektrodenlageabhängige interindividuelle Unterschiede der interatrialen Relationen bei einer hämodynamisch individuellen Schrittmacherprogrammierung durchaus berücksichtigt werden müssen, kann von einer hämodynamisch optimalen rechtsatrialen Elektrodenlage mit eigenständigen hämodynamischen Effekten nicht gesprochen werden.

Randomized comparison of direct and provisional stenting in de novo coronary artery lesions: the RADICAL study

Hintergrund: Obwohl bisherige Berichte eine ausgezeichnete primäre Erfolgsrate und ökonomische Vorteile der direkten Stentversorgung gezeigt haben, steht die Bestätigung einer klinisch relevanten Restenosereduktion bisher aus.    Ziel: Studienziel war der Vergleich von Restenoserate (primärer Endpunkt), prozeduraler Erfolgsrate, Durchleuchtungszeit, Kontrastmittelmenge und klinischem Verlauf (sekundäre Endpunkte).    Methoden und Ergebnisse: Zwischen Januar und Dezember 1999 wurden 250 Patienten randomisiert mit direkter Stentversorgung (DS, 125 Patienten) oder primärer Ballonangioplastie mit sekundärer Stentversorgung nur bei Notwendigkeit (PB, 125 Patienten) behandelt und 7,9±2,7 (6–9) Monate nachbeobachtet. Eine Kontrollangiographie konnte bei 92,0% der Patienten ausgeführt werden. Die prozedurale Erfolgsrate betrug 92,8% in Gruppe DS und 100% in Gruppe PB (n.s.). Die Durchleuchtungszeit in Gruppe DS (4,7±4,3 min) war signifikant (p<0,0001) geringer als in Gruppe PB (5,1±1,8min). Der Kontrastmittelbedarf unterschied sich nicht signifikant (DS 131±62ml, PB 139±36ml). Die direkte Stentversorgung erbrachte eine relative Reduktion der Restenoserate von 25,0% (15,7% in DS versus 20,9% in PB) ohne statistische Signifikanz zu erreichen. Gleichzeitig fand sich ein Trend zu weniger kardialen Ereignissen in der Gruppe DS (16,8% versus 21,6% in PB).    Schlussfolgerungen: Die direkte Stentversorgung ist zumindest so sicher und effektiv wie eine Stentversorgung nach Ballonvordilatation. Eine signifikante Reduktion der Restenoserate oder Verbesserung des klinischen Verlaufs in 6 Monaten konnte jedoch nicht gezeigt werden. Mögliche Vorteile der direkten Stentversorgung in einzelnen Subgruppen von Patienten können nur in größeren Studien erkannt werden. Background: Although preliminary reports have demonstrated excellent primary success and improved economics with direct stenting, a clinically relevant reduction of restenosis rate has not been documented yet.    Aims: Aims of the study were the comparison of restenosis rate (primary endpoint), procedural success, fluoroscopy time, amount of contrast dye and clinical outcome (secondary endpoints). Methods and results: Between January and December 1999, 250 patients were randomly assigned either to direct stent implantation without predilatation (DS; 125 patients) or provisional stenting (PB; 125 patients) and followed for 7.9±2.7 (6–9) months. Angiographic follow-up was available in 92.0% of patients. Procedural success rate was 92.8% in DS and 100% in PB (n.s.), while radiation exposure was lower (4.7±4.3 versus 5.1±1.8min; p<0.0001) with DS. Conversely, the amount of contrast dye (131±62 versus 139±36 ml; n.s.) was not different between DS and PB. Direct stenting leads to a 25.0% reduction in binary restenosis rate (15.7% in DS versus 20.9% in PB), indicating an advantageous trend, missing however the level of statistical significance. Similarly, there was a trend to fewer major cardiac events with DS (DS 16.8%, PB 21.6%).    Conclusions: We conclude that direct stenting is at least as safe and efficacious as balloon dilatation followed by provisional stent implantation, but failed to reduce restenosis rate or improve outcome within 6 months. Larger prospective randomized trials are required to assess the potential of direct stenting to reduce restenosis rate and improve clinical outcome in subgroups of patients.