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G H von Knorre

Publications and source records attributed to G H von Knorre.

At least 19 recordsLinked to original sources
PubMed2006

[WPW cases in the literature prior to the publication of Wolff, Parkinson and White in 1930].

In 1930, Wolff, Parkinson and White described the clinical entity of what is today known as the preexcitation or WPW syndrome. In the preceding literature, the authors found four comparable cases. Later on, seven further cases published prior to 1930 were discovered. An analysis of the altogether eleven cases displays that, in addition to the anomalous ECG in sinus rhythm, nearly all typical electrocardiographic findings during the tachyarrhythmias are found in this early literature. As tachycardia ECGs especially help to understand the mechanism of the WPW syndrome, the question is discussed whether already Wolff, Parkinson and White would have been able to give the correct interpretation of the mechanism if they had taken into consideration their own tachycardia ECGs as well as those known to them from the literature.

Electrocardiography↗
PubMed2006

[Feasibility and safety of long-term AAI(R) pacing in isolated sinus node syndrome].

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.

Aged↗
PubMed2006

[Left ventricular electromechanical latency period is an additional indicator to upgrade from right to biventricular DDD pacing].

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.

Bradycardia↗
PubMed2003

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

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+/-1.8 min; 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.

Aged↗
PubMed1993

[Anticoagulation: assessment of benefits and risks].

Thromboembolism is a frequent complication of atrial fibrillation. As could be demonstrated by several placebo-controlled prospective studies in the recent years the rate of thromboembolism was reduced significantly by anticoagulation of nearly all kinds of atrial fibrillation. These results are challenging to weigh risks and benefits in every patient. The principles which have to consider in this calculation are discussed with regard to the knowledge derived from the controlled studies.

Anticoagulants↗
PubMed1992

Right ventricular conductance to establish closed-loop pacing.

Innovations in pacing technology, which include the addition of rate-responsive features to programmable pacemakers, can improve the quality of life of patients suffering from sick sinus syndrome. Among the strategies providing rate-adaptive cardiac pacing, the most attractive is the physiological restoration of closed-loop chronotropic control. This paper describes how autonomic nervous system (ANS) control information is extracted from dynamic measures of myocardial contractile performance obtained from unipolar conductance measurements using the stimulation electrode in the right ventricular cavity. The pacemaker uses the ANS information to modulate pacing rate and restore normal physiological control of heart rate. A new algorithm, regional effective slope quantity (RQ), for isolating the ANS signal was developed. The resulting signal, ventricular inotropic parameter (VIP), is a normalized parameter proportional to the strength of the ANS inotropic signals to the myocardium. The efficacy of the ANS control concept was evaluated in multi-centre studies. Patients with AV block and VIP-controlled pulse generators performed defined exercise protocols. The ANS-controlled pacing rate and the spontaneous sinus rate were closely correlated. Blood pressure and subjective patient reports further indicated that good control of the cardiovascular circulation was achieved.

Autonomic Nervous System↗
PubMed1992

Autonomic nervous system controlled closed loop cardiac pacing.

A multicenter clinical study is presented, which focuses on the reestablishment of closed loop cardiac control in patients with chronotropic insufficiency. Using the information about sympathetic tone contained in the myocardial contractility, it is possible to reconnect the heart rate to the physiological control mechanisms. Intracardiac impedance is measured with the ventricular electrode and the ventricular inotropic parameter (VIP) is derived from that. The VIP serves directly as input to the control of heart rate by the pacemaker. Over 200 patients have received autonomic nervous system (ANS) controlled pacemakers. The patient-pacemaker system was investigated in different ways. This included standard exercise tests, long-term studies of every day activities over 24 hours, psychological, and pharmacological challenges. To prove the validity of the approach we specifically looked at (1) the appropriateness of changes in paced heart rate with sympathetic tone during exercise, (2) the correlation between heart rate and sinus rate, if detectable, and (3) the correlation between the echocardiographically determined preejection period (PEP) and the VIP controlled heart rate.

Autonomic Nervous System↗
PubMed1992

[Measuring intracardiac impedance for the determination of sympathetic nerve activity in frequency-adapted electrostimulation--Part 2: Clinical results].

The results of a multicenter clinical study involving patients receiving the first ANS controlled rate adaptive pacemaker are presented. In the patients with primary or secondary chronotropic insufficiency, it is possible to reestablish the closed loop control system that includes the baroreceptors, the medulla oblongata, the cardiac output and the mean arterial blood pressure. This system serves to keep the blood pressure constant in the face of changing demands on the circulation. Utilizing intracardiac impedance measurements, the myocardial contractility can be determined, which contains information about the current sympathetic tone, and thus represents an excellent physiological input for a rate adaptive mechanism. The results presented are taken from a study population of over 200 patients. The objective evaluation of this new approach was performed echocardiographically, by ergometry and 24-hour Holter monitoring.

Adult↗
PubMed1983

[Paroxysmal AV tachycardia in triplets].

It is reported on triplet sisters with paroxysmal tachycardias. Two of them were enzygotic. For the two an AV-node longitudinal dissociation could be proved as cause of the tachycardia. This observation is regarded as proof for the existence of congenital anomalies of the AV-node as a possible cause of its longitudinal dissociation.

Atrioventricular Node↗
PubMed1983

[Diagnosis and therapy of bradycardial arrhythmias].

Diagnostic and therapeutic procedures in bradyarrhythmias are discussed. Special attention is paid to cases with suspected but still undocumented bradycardias and to some aspects of differential therapy.

Bradycardia↗
PubMed1982

[Identification of the site of block in high degree AV conduction disorders on the surface ECG].

The possibility of identifying the site of block by analysing the surface ECG was studied in 124 patients with 2nd or 3rd degree AV-block. In all cases His-bundle-electrography was performed. With regard to the QRS-duration (both in conducted and in escape beats) and to functional peculiarities of the AV-conduction or of the automatic centres in patients with narrow QRS complexes nearly all cases with the prognostically less favourable His-Purkinje-block are discernible.

Bundle of His↗
PubMed1982

[Supplemental device for the electrocardiograph 6 NEK 4 for the recording of esophageal electrocardiograms].

For the analysis of the cardiac rhythm an additional device for recording electrocardiograms of the oesophagus which can be connected with the 6-canal-electrocardiograph 6 NEK 4 was developed. The device works as an ECG-preamplifier with a high reverse of amplification. Using a special filter it is possible to get well evaluable records excluding each zero line drift, even on most difficult conditions. The possibility of connection with any experimental entry of the 6 NEK 4 renders possible the combination of the electrocardiogram of the oesophagus with any ECG standard deviation program.

Cardia↗
PubMed1981

[The Lown-Ganong-Lewin syndrome--a rhythmologic unit?].

13 patients with the clinical diagnosis of a LGL-syndrome underwent a comprehensive analysis on account of therapeutically problematical tachycardias. In all cases the electrophysiological findings at most spoke for a partial av-node-shunt or for a small av-node, never for a complete bypass. The analysis of the tachycardia possible in 12 cases showed various mechanisms which by a stimulus circulating over a partial av-node-shunt could be explained in the sense of tachycardia only in 3 patients. It is concluded that different mechanisms underlie the clinically homogeneous picture of the LGL-syndrome concerning the development of a tachycardia.

Arrhythmias, Cardiac↗
PubMed1979

The optimization of the pulse delivered by the pacemaker.

The results of stimulation threshold analysis carried out in 230 patients after the initial electrode implantation, and in 188 patients during pacemaker replacement, are presented. The electrodes investigated were the IE-60K-10 (279 cases), the IE-60-K (96 cases) and the ME-50 (26 cases). The chronic stimulation threshold voltage for the electrode IE-60K-10 (electrode surface area: 10 mm2) at a pulse width of 0.5 ms, after an electrode function time of 25 months, is 2.05 +/- 0.18 V, representing 256% of the acute threshold, and is equally as high as the chronic figure for the IE-60-K electrode (surface area: 27 mm2) measured at 2.08 +/- 0.20 V. The current threshold for the IE-60K-10 increased from 0.78 +/- 0.07 mA by 299% to 2.33 +/- 0.30 mA and was thus, as expected, lower than that of the large area electrode IE-60-K, which increased from 1.11 +/- 0.22 mA to 3.23 +/- 0.43 mA (291%). On the basis of the computation of the stimulation threshold energy and the stimulation threshold charge, a reduction of pulse duration to below 0.5 ms would not appear to make such energy-saving sense.

Electrodes, Implanted↗