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D Krüger

Publications and source records attributed to D Krüger.

At least 19 recordsLinked to original sources
PubMed2006

Relationship between therapeutic time intervals and intermediate term left ventricular systolic function in patients treated with facilitated percutaneous coronary intervention for acute myocardial infarction.

BACKGROUND: The concept of initiating fibrinolytic therapy in patients who cannot undergo immediate percutaneous coronary intervention (PCI) in the setting of acute ST-segment-elevation myocardial infarction (STEMI) has been proposed as a strategy to improve outcomes. However, evidence supporting the use of this strategy is not conclusive, and the results of recent randomized controlled trials are apparently contradictory. Probably, the time points of administration of the adjunctive thrombolytics and antiplatelet agents and the time loss until coronary intervention have a major influence on the discrepancy of outcomes in different trials. Therefore, the relationship between therapeutic time intervals and outcome in patients treated with facilitated PCI has been analyzed. METHODS: In this single center retrospective study, 131 patients with STEMI were treated with a combined pharmaco-mechanical reperfusion strategy using half-dose r-tPA combined with a glycoprotein (GP) IIb/IIIa antagonist prior to PCI. Specific time points were recorded for each patient, including the time of symptom onset, the time of first medical contact, the start of intravenous thrombolysis, the time of administration of the GP IIb/IIIa antagonist and the start of coronary intervention. We then examined the relationship between the time delay from symptom onset to the initiation of various steps of treatment and the residual myocardial damage as expressed by the severity of both global and regional myocardial dysfunction calculated from a left ventriculography study performed 3 months later. RESULTS: The median time from symptom onset to the first medical contact, with 25th and 75th percentiles in parentheses, was 1.25 h (0.75, 3), from symptom onset to initiation of thrombolytic therapy 2.25 h (1.25, 3), to initiation of GP IIb/ IIIa inhibitor therapy 3.5 h (2, 5.69), and to the start of coronary intervention 4.81 h (2.85, 7.91). The time between symptom onset and initiation of both thrombolytic therapy and coronary intervention was significantly related to the global ejection fraction and to the extent of regional hypokinesia at the 3-month follow-up (p<0.05). The time to the initiation of GP IIb/IIIa inhibitors was only significantly related to the global ejection fraction (p<0.05), while the time to the first medical contact did not show a similar relationship (p>0.05). Furthermore, we observed a significant relationship between the infarct-related artery (IRA) patency at the initial angiogram and the residual regional myocardial damage at follow-up; normokinesia at follow-up was found in 61.3% of patients with an initially patent IRA and in 41.2% of patients with an initially occluded IRA, whereas severe hypokinesia was found in 13.8% and 37.3%, respectively (p<0.05). CONCLUSION: In patients with STEMI treated with a facilitated PCI strategy using half dose r-tPA in combination with a glycoprotein IIb/IIIa receptor blocker, the 3-month global and regional residual myocardial dysfunction is significantly related to the time elapsed between the onset of symptoms and the start of both fibrinolytic therapy and coronary intervention.

Adult↗
PubMed2005

[Acute coronary syndrome after diclofenac induced coronary spasm].

We report about a 67-year old man, who was submitted to our clinic with acute coronary syndrome. The cardiac catheterization showed a proximal thrombus in the left anterior descending (LAD). The other coronary arteries did not have significant lesions. After percutaneous transluminal coronary angioplasty with stent-implantation into the proximal LAD the patient remained clinically stable. Cardiac enzymes confirmed no myocardial necrosis. Three days after the acute coronary syndrome the patient developed a podagra, which was treated with colchicinum, diclofenac and local cooling. Five hours after initial therapy the patient developed severe symptoms of angina pectoris and electrocardiographical signs of an acute posterior and anterior myocardial infarction. Immediate coronary angiography demonstrated extended vasospasm of the right coronary artery. Intracoronary application of verapamil and nitroglycerin resolved the coronary spasm. The patient reported about a self-indicated application of diclofenac six hours before hospital admission. This case demonstrates that oral application of diclofenac can provoke coronary vasospasm.

Acute Disease↗
PubMed2002

[Pullback atherectomy. An alternative procedure in the treatment of coronary stenosis and in-stent restenosis].

Optimized directional coronary atherectomy (DCA) has shown significantly superior acute and long-term results compared to conventional balloon angioplasty (BA). Nevertheless DCA has remained a niche application due to specific procedural aspects. The pullback atherectomy catheter (PAC), developed to retrieve atheromatous plaque material, is an alternative debulking device. We report on clinical and angiographic experience in 55 consecutive patients, in whom de novo lesions (35 pts) as well as instent restenoses (17 pts) were treated. The minimal luminal diameter (MLD, mm) rose after PAC and additional BA from 1.06 +/- 0.53 to 2.68 +/- 0.48 and from 1.10 +/- 0.48 to 2.55 +/- 0.49 mm, respectively. A stenosis reduction from 69 +/- 13 to 19 +/- 16 and from 64 +/- 15 to 16 +/- 10%, resp., could be documented. After 3-6 months a complete angiographic follow-up showed MLD values of 2.01 +/- 0.69 and 1.88 +/- 0.61 mm. Nine of 35 (26%) vs. 5 of 17 (29%) pts developed significant restenosis at the treated site (diameter stenoses > 50%). Stent implantation was necessary to achieve an optimal acute angiographic result or due to dissection in 17 vs. 5 pts. Major cardiac events did not occur; however, two restenosed coilstents were removed by PAC. With the pullback atherectomy catheter, a safe and effective alternative device is available for the treatment of coronary lesions and also of in-stent restenosis. Promising short and acceptable long-term results are comparable to those of other debulking procedures.

Aged↗
PubMed2001

Characterization and mutagenesis of the recombinant N-acetylneuraminate lyase from Clostridium perfringens: insights into the reaction mechanism.

The N-acetylneuraminate lyase from Clostridium perfringens was expressed in Escherichia coli as a fusion protein with a His-tag and purified to homogeneity using metal chelate affinity and anion exchange chromatography. The purified enzyme has a pH optimum of 7.6 and a temperature optimum of 65-70 degrees C. In kinetic studies the lyase exhibits a Km of 3.2 mM for Neu5Ac and a Vmax of 27.5 U x mg(-1). To clarify the functional role of some putative active site residues, site-directed mutagenesis was performed. Lysine 161 was identified as the residue forming the Schiff base intermediate with the substrate. Tyrosine 133 was shown to be also a catalytically important residue; it seems to function as an acceptor for the proton of the C4 hydroxyl group, as already suggested by other groups. Furthermore, it is involved in stabilizing the Schiff base intermediate. Mutations of aspartate 187 and glutamate 188 indicate that both residues are involved in substrate binding. In this respect the carboxy group of aspartate 187 seems to be particularly important. Based on the results of these studies, a model of the reaction mechanism is discussed.

Amino Acid Substitution↗
PubMed2001

Quantitative detection of Toxoplasma gondii DNA in human body fluids by TaqMan polymerase chain reaction.

OBJECTIVE: A new quantitative polymerase chain reaction (real-time PCR) was designed to detect Toxoplasma DNA in human body fluid samples. METHODS: Real-time fluorescence detection of amplification product formation on the basis of the TaqMan-System was established with Toxoplasma 18S rDNA as a target gene. RESULTS: The method provides a high sensitivity comparable to conventional nested PCR procedures and generates quantitative data when detecting toxoplasmic DNA in human blood, cerebrospinal or amniotic fluid. Moreover, data were obtained investigating blood samples from an immunocompromised patient with reactivated toxoplasmosis after allogeneic bone marrow transplantation, monitoring the therapeutic effect. CONCLUSIONS: The potential application of this method to detect Toxoplasma DNA in body fluids and to follow the development of parasitemia under therapy could be demonstrated.

Animals↗
PubMed2000

Diagnosis of toxoplasmosis in bone marrow transplant recipients: comparison of PCR-based results and immunohistochemistry.

Toxoplasmosis in bone marrow transplant recipients is a rare but serious complication and if untreated, almost uniformly fatal. The diagnosis, however, remains difficult. We therefore compared serial determination of antibody titers specific for T. gondii before and after transplantation, serial PCR for T. gondii DNA in serum, PCR and nested PCR for T. gondii DNA in various tissues, conventional histology and immunohistochemistry for detection of parasites in three patients with autopsy-confirmed toxoplasmosis after bone marrow transplantation. Immunohistochemistry demonstrated the presence of parasites in 13 out of 20 organs investigated (65%), whereas PCR detected T. gondii-specific DNA in 15 out of 20 organs (75%). Immunohistochemistry revealed concordant results to PCR data in 60% of the specimens. With the use of a nested PCR protocol, eight out of nine samples (89%) were positive for T. gondii-specific DNA. The combination of both methods detected the presence of parasites in 90% of the specimens. Serial PCR in serum did not yield positive results. Neither PCR nor immunohistochemistry was able to detect parasites in all organs investigated, but both methods together improved sensitivity to 90% and consequently, should be used jointly to maximize diagnostic precision. Bone Marrow Transplantation (2000) 25, 1257-1262.

Adult↗
PubMed1999

Exercise-induced myocardial ischemia in isolated coronary artery ectasias and aneurysms ("dilated coronopathy").

OBJECTIVES: The purpose of our study was to evaluate the clinical significance of isolated coronary artery ectasias or aneurysms (CEA). BACKGROUND: It has been postulated that altered coronary blood flow in CEA predisposes patients to the development of myocardial ischemia (CI) and infarction. METHODS: Sixty-seven patients with bilateral nonobstructive CEA without associated cardiac defects ("dilated coronaropathy") were derived from 16,341 cardiac catheterizations between 1986 and 1997. Ectasias were defined as luminal dilation of 1.5- to 2.0-fold, aneurysms of >2.0-fold of normal limits. Eleven of 25 patients presented with myocardial infarction due to an occlusion of the infarct vessel. In 42 patients without infarction (study group), exercise-induced CI was investigated. RESULTS: A corresponding CI was documented in 32 of 42 patients in a coronary sinus lactate study (reduced lactate extraction 5.6 +/- 4.1%) and in 29 of 40 patients in an ergometry (0.25 +/- 0.06 mV ST depressions). The results differed significantly from a control group of 29 patients without heart disease (p < 0.001). Nitroglycerin (0.8 mg) provoked a further significant deterioration of CI in the 32 of 42 developing a frank cardiac lactate production (-2.6 +/- 6.8%, p < 0.001). The metabolic extent of CI was significantly correlated to the coronary diameters of the proximal and middle segments of left anterior descending artery and the middle segment of left circumflex artery (r = 0.87, p < 0.001). Stigmata of an impaired coronary blood flow such as delayed antegrade filling, segmental backflow phenomenon and local deposition of dye were found significantly more often with increasing coronary diameters (p < 0.04). CONCLUSIONS: "Dilated coronaropathy" is an entity of nonobstructive, ischemic coronary artery disease. Nitroglycerin is of no therapeutic benefit but leads to an aggravation of exercise-induced CI.

Coronary Aneurysm↗
PubMed1999

[Cardiac endothelin release into the coronary sinus in myocardial ischemia and coronary endothelial injury].

UNLABELLED: Endothelin has both vasoconstrictor and mitogenic properties and might, therefore, play a role in the pathogenesis of acute coronary syndromes and coronary atherosclerosis. The aim of the study was to characterize the mechanisms and kinetics of cardiac endothelin-1 (ET-1) release following a local endothelial injury during PTCA (group A) and after sustained myocardial ischemia (group B). Additionally, the precision of agreement between measurements in coronary sinus and peripheral venous samples should be analyzed. In group A, elective PTCA was performed in 20 patients with stable angina pectoris and a > 70% type A stenosis. Simultaneous determinations of ET-1 from coronary venous and peripheral venous blood were done before balloon inflation and during the several hours following the last dilatation procedure. A coronary sinus study with high rate atrial pacing was performed in 20 group B patients with coronary multivessel disease. ET-1 was determined from coronary sinus and peripheral venous blood samples prior to stimulation and during several hours after cessation of pacing. Control groups were provided for both groups. The control group consisted of 10 patients with coronary angiography without PTCA for group A and 10 patients with angiographic normal coronary arteries for group B.PTCA induced an instantaneous increase of coronary sinus ET levels from 4.1 +/- 1.1 pg/ml to 13.7 +/- 2.3 pg/ml (peripheral venous 7.9 +/- 2.5 pg/ml), which was more pronounced if the target vessel was the left anterior descending artery. This peak was followed by a gradual decrease of ET-1 to the limit of normal within 6 hours. The concentrations of ET, furthermore, remained higher in the coronary sinus compared with the peripheral vein indicating a persisting cardiac release of ET. In group B, incremental atrial pacing resulted in myocardial ischemia, and a significant increase in ET-1 from 4.6 +/- 0.6 pg/ml to 13.1 +/- 2.8 pg/ml was detected in the coronary sinus samples. A persistent cardiac release of ET-1, as reflected by sustained elevated coronary sinus concentrations, was observed for up to one hour after cessation of pacing. The analysis of measurement agreement between coronary venous and peripheral venous samples revealed considerable variations of the differences between the two sampling sites indicating wide limits of agreement. Despite a significant positive correlation, our date reflecting a remarkable lack of agreement. CONCLUSIONS: 1) An enhanced release of ET-1 following PTCA is mainly due to the localized endothelial injury, and the ET-1 levels remain elevated for up to hours after the mechanical stimulus. 2) A short-lasting myocardial ischemia is associated with a significant ET-1 increase. 3) For refined evaluations of release kinetics of cardiac ET-1, blood sampling from the coronary sinus seems to be essential.

Aged↗
PubMed1999

Lactitol tolerance in healthy Thai adults.

The hydrogen breath analysis test was performed in healthy Thai adults to determine lactitol tolerance. The study was conducted in 39 individuals (11 males and 28 females) aged 18-41 years. All volunteers agreed to participate in this study after the risks and benefits had been fully explained. Subjects were requested not to consume milk, milk products, or high-vegetable diets for a day and to fast from 10 p.m. of the day preceding the test day. After consumption of the test diet (12 and 20 g of lactose or lactitol, respectively, in 250 mL water), the subjects recorded the severity of symptoms for 24 hours. Breath samples were collected after fasting and after consumption of the test diet at 30 min intervals over the 7-hour study period. Breath samples were analyzed for hydrogen using gas chromatography. After consumption of 12 g lactose, the prevalence of lactose malabsorbers was established. The increment of a peak breath hydrogen level of > or = 20 ppm above the baseline level was used as an indicator of lactose malabsorption. The lactose malabsorbers were further classified as lactose tolerance or lactose intolerance according to the gastrointestinal symptoms observed. All 39 healthy Thai adults could be classified into 3 groups as follows: 9 (23%) lactose absorbers (LA), 15 (38.5%) lactose mal-absorber/tolerance (LMT), and 15 (38.5%) lactose mal-absorber/intolerance (LMI). Using the hydrogen breath test, 67% of the subjects were identified as lactitol intolerance after the consumption of 12 g lactitol. The lactitol intolerance comprised 53.8% of LMI, 34.6% of LMT, and 11.5% of LA. Among all subjects, one third of LA (33%), two thirds of LMT (60%), and 93% of LMI were lactitol intolerant. In addition, gastrointestinal symptoms such as flatulence and abdominal pain were most pronounced in LMI. Diarrhea was also a prominent manifestation after consumption of 12 g lactitol. Therefore, it was finally decided that 20 g lactose or lactitol were not given to LMI because of the risk of gastrointestinal symptoms. After high doses (20 g) of lactose and lactitol consumption, most LMT developed more symptoms than did LA and the main symptom was diarrhea. Consumption of 20 g lactose resulted in fewer symptoms than 20 g lactitol in both LA and LMT. On the basis of the hydrogen breath test, most LA tolerated 12 g lactitol without gastrointestinal symptoms except some flatulence whereas most LMT and LMI did not. Twenty g lactitol was not tolerated by both LA and LMT because there was diarrhea among the subjects, especially in LMT. Although the hydrogen breath analysis test is the best method for identification of lactose malabsorption, it is not the best method to identify lactitol intolerance. A hydrogen concentration of 15 ppm above the baseline level was found to be the best cut-off point to indicate lactitol intolerance although sensitivity was 85% and specificity only 38% in this study. It was further concluded that there is a greater susceptibility to lactitol in human lactose malabsorbers than in lactose absorbers. Our findings might be relevant for the limited use of lactitol in Thailand.

Absorption↗
PubMed1999

Nicotinamide and methionine reduce the liver toxic effect of methotrexate.

Methotrexate is widely used as a therapeutic agent in different diseases. This therapy is connected with various side effects, including liver toxicity. We have developed a mouse model to demonstrate the toxic effects of methotrexate: mice were given 50 mg/kg acetaminophen, which itself has no effect on the liver. If, additionally, methotrexate is applied, there is an increase in the death rate, as well as in glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) activities. If methotrexate is administered in conjunction with either nicotinamide or methionine, the rise in the death rate and in GOT and GPT activities associated with methotrexate application is markedly reduced. On the basis of these results, it can be concluded that methotrexate therapy should be combined with either nicotinamide or methionine, respectively.

Acetaminophen↗
PubMed1999

The terminal enzymes of sialic acid metabolism: acylneuraminate pyruvate-lyases.

The acylneuraminate pyruvate-lyase gene from Clostridium perfringens was sequenced and found to be most similar to the lyase gene from Haemophilus influenzae. Both the recombinant clostridial enzyme and the native enzyme from pig kidney were purified in larger amounts and characterized. The properties of the porcine lyase are similar to the microbial ones. However, the much higher degree of similarity in comparison to the microbial enzymes that was found between porcine lyase peptides and two putative mammalian lyase sequences show that the latter form an own group apart from the microbial lyases. Actual models of the acylneuraminate pyruvate-lyase reaction are discussed.

Amino Acid Sequence↗
PubMed1998

A second European collaborative study on polymerase chain reaction for Toxoplasma gondii, involving 15 teams.

In order to investigate the accuracy and practicability of the polymerase chain reaction (PCR) in the antenatal diagnosis of congenital toxoplasmosis, a collaborative study involving 15 European laboratories was performed under the auspices of the Biomed 2 Programme of the European Community. Each team received 12 aliquots (four negative, eight positive) of 'artificial samples' made of amniotic fluid spiked with tachyzoites of the RH strain of Toxoplasma gondii. Each team performed its own PCR protocol (all were different). Nine of the 15 laboratories were able to detect a single parasite, but two of the 15 found all samples negative. Four of the 15 laboratories found one or more control samples to be falsely positive. This study highlights the lack of homogeneity between PCR protocols and performance and underlines the need for an external quality assurance scheme which could provide 'reference' samples that could be used by any laboratory wanting to establish and maintain an accurate diagnostic test based on PCR.

Amniotic Fluid↗
PubMed1998

Cardiac release and kinetics of endothelin after uncomplicated percutaneous transluminal coronary angioplasty.

This study was designed to assess the release kinetics of endothelin after percutaneous transluminal coronary angioplasty (PTCA) and to prove the coronary endothelium as the source of the endothelin release. Twenty-seven patients with single-vessel coronary artery disease underwent PTCA. Endothelin, troponin T, myoglobin, and creatine phosphokinase paired blood samples were withdrawn from the coronary sinus and a peripheral vein before the balloon maneuver and at 1, 5, 10, 30, 45 minute(s), and at 1, 2, 3, 6, 12, and 24 hour(s) after the last balloon maneuver. Myocardial ischemia was monitored by means of cardiac lactate metabolism and 12-lead electrocardiogram. Thirteen patients who underwent a diagnostic cardiac catheterization served as a control group. In the left coronary artery, PTCA (n = 19) endothelin concentrations increased from 4.1 pg/ml as a common mean baseline level before intervention to 13.9 +/- 2.6 pg/ml (mean +/- SD) in the coronary sinus and 7.9 +/- 2.2 pg/ml (mean +/- SD) in the peripheral vein at 1 minute after the intervention (p <0.001). The levels remained elevated for 3 hours with higher coronary sinus than peripheral venous concentrations due to persistent cardiac endothelin release. PTCA of the right coronary artery (n = 8) also led to an instantaneous endothelin increase from a mean concentration of 4.4 before intervention to 8.3 pg/ml after intervention with identical coronary sinus and peripheral venous levels (p <0.001). Endothelin levels gradually decreased to normal within 6 hours. No patient developed a measurable myocardial ischemia or a myocardial infarction. In the control group all parameters remained unchanged. Uncomplicated PTCA was followed by a significant cardiac endothelin release that seems to indicate endothelial injury and not myocardial ischemia.

Aged↗
PubMed1998

Relation between QT dispersion and the extent of myocardial ischemia in patients with three-vessel coronary artery disease.

The aim of the study was to examine the relation between the extent of myocardial ischemia and changes in QT interval dispersion in patients with obstructive coronary artery disease and in patients with normal coronary arteries. QT interval dispersion reflects regional variations in ventricular repolarization and cardiac electrical instability. Previous studies showed QT interval dispersion changes during episodes of myocardial ischemia in patients with coronary artery disease, but no data on the relation between extent of myocardial ischemia and degree of QT interval dispersion changes are available. To assess the effects of myocardial ischemia on myocardial repolarization by analyzing the change in QT dispersion during incremental atrial pacing, we studied 33 patients (7 women and 26 men, mean age 60.1 +/- 5.1 years, 18 patients with normal coronary arteries, 15 patients with coronary 3-vessel disease). QT dispersion was measured at baseline, after each pacing period, within 30 seconds after cessation of pacing ("peak ischemic stress"), and at 1-minute intervals for up to 5 minutes. Paired blood samples for determination of serum lactate were withdrawn from the coronary sinus and radial artery to determine the cardiac lactate extraction ratio at each point of electrocardiographic registration. In patients with coronary artery disease, QT dispersion increased from a baseline value of 39 +/- 7 ms to a peak ischemic stress value of 63 +/- 10 ms (p <0.0001). Patients with normal coronary arteries showed almost unchanged values of QT dispersion (41 +/- 9 vs 42 +/- 7 ms). There was a significant relation between the pacing-induced change in QT dispersion and the induced change in myocardial lactate extraction ratio (r = 0.76, p <0.0001). The change in QT dispersion (baseline vs peak pacing stress) was related to the extent of the cardiac lactate extraction ratio (r = -0.79, p <0.0001). These data indicate that the severity or extent of induced myocardial ischemia was related to the degree of induced changes of the variability in the timing of the ventricular recovery pattern.

Aged↗
PubMed1998

Small intestinal transit and digestibility of lactitol in Wistar rats.

The study was conducted to evaluate if the recovery of lactitol and its cleavage products varied when different doses of this disaccharide sugar alcohol (150 and 1,200 mg/kg body weight, respectively) were given by gastric gavage to unadapted male rats. Phenol red added to the test solution as marker dye served to determine the intestinal transit and distribution areas. Marker transit revealed that the test substance did not reach the cecum in all series. Gastric emptying was more retarded after the high dose. Administration of low doses did not alter intestinal transit and luminal volume as compared to control animals. But a much larger luminal volume was found in the third intestinal quarter after the high doses, although the marker transit through this segment was equal under all experimental conditions. The total gastrointestinal recovery of lactitol at 63.2 (+/- 3.9) and 75.5 (+/- 4.5)% was significantly different (p < 0.001) 1 hour after administration of 150 mg and 1200 mg/kg body weight, respectively. Only free sorbitol was detected in the gastrointestinal contents in both dosage groups. Based on these results and correcting the values for marker recovery (85% in both groups), it is reasonable to assume that the maximum amount of lactitol that can be hydrolyzed and absorbed by the small intestine is 11.2 and 25.2%, respectively, and not zero. In conclusion, the caloric availability of lactitol is dose-dependent and should be determined under normal conditions in which the laxative threshold is not exceeded.

Animals↗
PubMed1998

Enhancement of the effect of methotrexate on collagen II induced arthritis in mice by nicotinamide.

Treatment with a combination of 10 mg/kg i.p. methotrexate and 100 mg/kg i.p. nicotinamide inhibits the development of collagen II induced arthritis in male DBA/1 X B.10(4R) mice, as assessed by the arthritic index and whole blood chemiluminescence. The effect is much more pronounced than with either methotrexate or nicotinamide alone at the same concentrations. Determination of GOT and GPT levels in the blood revealed that the treatment causes no toxic side effects on the liver.

Alanine Transaminase↗
PubMed1998

An optimized AV delay algorithm for patients with intermittent atrioventricular conduction.

Detection and promotion of an intermittent atrioventricular (AV) conduction is the objective of an AV delay hysteresis algorithm in dual chamber pacemaker (DDD) pacing. The AV delay following an atrial event is automatically extended by a programmable interval (AV hysteresis interval) if the previous cycle showed spontaneous AV conduction, i.e., a ventricular event was detected within the previous AV delay. An automatic search mode scans for spontaneous ventricular events during the hysteresis interval: a single AV delay extension (equal to the programmed AV delay hysteresis) will occur after a successive, programmable number of AV cycles with ventricular pacing. If a spontaneous AV conduction is present, the AV delay will remain extended by the hysteresis interval. Our first results in 17 patients with intermittent AV block disclosed a satisfactorily working algorithm with effective reduction of ventricular stimuli. In relation to the underlying conduction disturbance and pacemaker settings, the majority of our patients showed a reduction of ventricular pacing events up to 90% without any adverse hemodynamic or electrophysiological changes. Based on clinical (promotion of a physiological activation and contraction sequence) and technical (reduction of power consumption) advantages, the AV hysteresis principle could be of incremental value for future dual chamber pacing in patients with intermittent complete heart block.

Aged↗