Biomedical subjects

Peter Lercher

Publications and source records attributed to Peter Lercher.

7 recordsLinked to original sources

PubMed2007

Therapy with angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, and statins: no effect on ablation outcome after ablation of atrial fibrillation.

BACKGROUND: The renin-angiotensin-aldosterone system and inflammation are supposed to play a key role in the pathogenesis of atrial fibrillation (AF). This retrospective clinical study was intended to assess the influence of drugs with antiinflammatory and/or renin-angiotensin-aldosterone system-modulating properties, namely angiotensin-converting enzyme inhibitors (ACE-Is), angiotensin II receptor blockers (ARBs), and statins, on AF-free survival after AF ablation. METHODS: The study included 234 patients (23-80 years; 71.8% men) with drug-resistant paroxysmal (n = 165) or persistent AF (n = 69) who either underwent a Lasso-guided segmental pulmonary vein isolation (n = 83) or a CARTO-guided left atrial circumferential ablation (n = 151). Treatment with statins (n = 113), ACE-Is, or ARBs (n = 124), or a combination of a statin and an ACE-I or ARB (n = 75) was started >3 months before ablation and was continued during follow-up. RESULTS: After a median follow-up of 12.7 months, 64% of patients with paroxysmal and 45% of patients with persistent AF were free of AF. Statin use (hazard ratio [HR], 1.06; P = .79), ACE-I or ARB use (HR, 1.12; P = .59), and their combined use (statin + ACE-I/ARB; HR, 1.17; P = .54) did not significantly influence ablation outcome as assessed by Cox regression analysis. In addition, after multivariate adjustment for potential confounders, the examined drugs did not significantly affect ablation outcome. Ablation induced an acute up-regulation of C-reactive protein levels (preablation vs 48 hours postablation, 5.9 +/- 8.1 vs 33.7 +/- 30 mg/L; P < .001) and other inflammatory markers. The examined drugs did not significantly alter baseline levels or ablation-induced up-regulation of inflammatory markers. CONCLUSIONS: The routine use of statins, ACE-Is, or ARBs did not result in an improved outcome of AF ablation.

Adult↗

PubMed2006

Is inducibility of atrial fibrillation after radio frequency ablation really a relevant prognostic factor?

AIMS: The study was intended to assess the prognostic value of inducibility of atrial fibrillation (AF) after radio frequency ablation. METHODS AND RESULTS: Two hundred and thirty four patients with drug-resistant paroxysmal (n=165) or persistent AF (n=69) underwent either Lasso-guided segmental pulmonary vein isolation (n=83) or CARTO-guided left atrial circumferential ablation (n=151). After ablation, two attempts to induce AF (>1 min) by decremental coronary sinus stimulation were performed. Patients were followed for at least 6 months (median: 12.7 months). At 6 months of follow-up, 67% of patients with paroxysmal and 48% of patients with persistent AF were AF-free. Inducibility of AF was a significant predictor of AF recurrence in univariate [hazard ratio (HR)=2.32, P<0.001] and multivariable (HR=2.19, P<0.001) Cox regression analyses. The prognostic value of inducibility was present in both patients with paroxysmal (HR=2.38, P=0.001) and persistent AF (HR=1.91, P=0.034) and did not significantly differ between both ablation techniques. The sensitivity, specificity, positive, and negative predictive values of the AF induction test to predict the 6-month ablation outcome were 46.7, 75, 53.8, and 69.2%, respectively. CONCLUSION: Inducibility of AF after ablation is a significant predictor of recurrent AF. However, owing to the low diagnostic accuracy of the AF induction test, non-inducibility does not qualify as reliable procedural endpoint.

Atrial Fibrillation↗

PubMed2005

Influence of permanent right ventricular pacing on cardiorespiratory exercise parameters in chronic heart failure patients with implanted cardioverter defibrillators.

STUDY OBJECTIVES: Patients with chronic heart failure and implanted cardioverter-defibrillators (ICDs) may have a higher incidence of new-onset or worsening heart failure requiring hospitalization with dual-chamber ICDs compared with single-chamber ICDs. DESIGN AND SETTING: The purpose of this study was to show the impact of permanent right ventricular (RV) pacing on exercise capacity and related cardiorespiratory parameters in patients with chronic heart failure and ICDs. PATIENTS AND INTERVENTIONS: Seventeen patients with chronic heart failure and a dual-chamber ICD performed cardiopulmonary exercise testing (CPX) on 3 different days. After CPX 1, patients were randomized either to back-up pacing or permanent RV pacing. After 3 months, CPX 2 was performed and patients changed groups (crossover design); CPX 3 was performed after 3 additional months. MEASUREMENTS AND RESULTS: Maximal values for workload (108 +/- 46 W vs 117 +/- 48 W, p < 0.01), oxygen uptake (Vo(2)) [21.0 +/- 5.3 mL/min/kg vs 22.5 +/- 6.4 mL/min/kg, p < 0.05], oxygen pulse (13 +/- 3.7 mL vs 14 +/- 4.0 mL, p < 0.05), and metabolic equivalent (6.0 +/- 1.5 vs 6.4 +/- 1.8, p < 0.05) were significantly lower with permanent RV pacing compared to back-up pacing. Workload, Vo(2), and oxygen pulse were significantly reduced at the ventilatory anaerobic threshold, while workload and Vo(2) were significantly lower at the respiratory compensation point. No differences were found for maximal heart rate, minute ventilation Ve, and respiratory exchange ratio. The Ve/carbon dioxide production slope was significantly steeper with permanent RV pacing compared to back-up pacing. CONCLUSIONS: Permanent RV pacing significantly reduced maximal and submaximal measures of exercise. For patients with chronic heart failure and sufficient atrioventricular conduction, every effort should be made to minimize permanent right ventricular pacing.

Anaerobic Threshold↗

PubMed2004

Soft-computing base analyses of the relationship between annoyance and coping with noise and odor.

The majority of research on annoyance as an important impact of noise, odor, and other stressors on man, has regarded the person as a passive receptor. It was however recognized that this person is an active participant trying to alter a troubled person-environment relationship or to sustain a desirable one. Coping has to be incorporated. This is of particular importance in changing exposure situations. For large populations a lot of insight can be gained by looking at average effects only. To investigate changes in annoyance and effects of coping, the individual or small group has to be studied. Then it becomes imperative to recognize the inherent vagueness in perception and human behavior. Fortunately, tools have been developed over the past decades that allow doing this in a mathematically precise way. These tools are sometimes referred to by the common label: soft-computing, hence the title of this paper. This work revealed different styles of coping both by blind clustering and by (fuzzy) logical aggregation of different actions reported in a survey. The relationship between annoyance and the intensity of coping it generates was quantified after it was recognized that the possibility for coping is created by the presence of the stressor rather than the actual fact of coping. It was further proven that refinement of this relationship is possible if a person can be identified as a coper. This personal factor can be extracted from a known reaction to one stressor and be used for predicting coping intensity and style in another situation. The effect of coping on a perceived change in annoyance is quantified by a set of fuzzy linguistic rules. This closes the loop that is responsible for at least some of the dynamics of the response to a stressor. This work thus provides all essential building blocks for designing models for annoyance in changing environments.

Adaptation, Psychological↗

PubMed2003

[The impact of the Multicenter Automatic Defibrillator Implantation Trial II in a university hospital--do all patients with myocardial infarction and reduced left ventricular function need an implantable cardioverter-defibrillator?].

BACKGROUND AND OBJECTIVES: Patients with coronary artery disease (CAD) and severely compromised left ventricular ejection fraction are at high risk to die from sudden cardiac death. The Multicenter Automatic Defibrillator implantation Trial II (MADIT II) shows a significant benefit of a cardioverter-defibrillator (ICD) therapy compared to standard treatment alone in this selected group of patients. The objective of the present study was to investigate the number of patients who will fulfil the MADIT II criteria and are candidates for prophylactic ICD implantation. METHODS AND MATERIAL: From January to December 2001 a total of 2653 patients underwent coronary angiography at our institution due to angina pectoris, positive exercise stress testing, pathological SPECT myocardial perfusion images, suspected dilated cardiomyopathy or ventricular arrhythmias. According to the MADIT II inclusion criteria patients with significant coronary artery disease (diameter stenosis > 50%), ejection fraction < 0.31% and previous myocardial infarction were included. Exclusion criteria were acute coronary syndromes, patients with ventricular tachyarrhythmias or an existing indication for ICD therapy, and patients with coronary artery bypass graft surgery or percutaneous transluminal coronary angioplasty within the past or following three months. RESULTS: Out of 2653 patients 185 (7%) had an ejection fraction less than 0.31, 149 (5.6%) showed significant coronary artery stenosis and 70 (2.6%) patients fulfilled the MADIT II criteria. The mean age of these patients was 68 +/- 9 years, the left ventricular ejection fraction 24 +/- 6. In 37 patients an ICD system was implanted according to the existing guidelines. 70 patients met the MADIT II inclusion criteria, resulting in an increase of 189% of ICD implantations per year. CONCLUSION: 2.6% out of 2653 patients who were referred to coronary angiography fulfilled the criteria of MADIT II. The expanding indication for ICD therapy will result in an annual increase of 70 (189%) prophylactic ICD implantations in our study population.

Aged↗

PubMed2003

A fuzzy rule based framework for noise annoyance modeling.

Predicting the effect of noise on individual people and small groups is an extremely difficult task due to the influence of a multitude of factors that vary from person to person and from context to context. Moreover, noise annoyance is inherently a vague concept. That is why, in this paper, it is argued that noise annoyance models should identify a fuzzy set of possible effects rather than seek a very accurate crisp prediction. Fuzzy rule based models seem ideal candidates for this task. This paper provides the theoretical background for building these models. Existing empirical knowledge is used to extract a few typical rules that allow making the model more specific for small groups of individuals. The resulting model is tested on two large-scale social surveys augmented with exposure simulations. The testing demonstrates how this new way of thinking about noise effect modeling can be used in practice both in management support as a "noise annoyance adviser" and in social science for testing hypotheses such as the effect of noise sensitivity or the degree of urbanization.

Attitude↗

PubMed2002

Exercise does not affect plasma concentrations of (R)- and (S)-carvedilol.

PURPOSE: In vitro studies have shown that beta-blockers are taken up into and released from adrenergic cells. As a consequence, plasma concentrations of beta-blockers increase during exercise together with those of epinephrine and norepinephrine. However, effects of exercise on plasma concentrations of (R)- and (S)-carvedilol are unknown. METHODS: Twelve healthy males received oral single doses of 12.5 mg (R)-carvedilol, 12.5 mg (S)-carvedilol and 25 mg (R,S)-carvedilol in a cross-over fashion; 11 patients with essential arterial hypertension were given 25 mg (R,S)-carvedilol. Exercise was performed 3 hours following drug intake, and blood samples were taken at rest, at the end of exercise, and after 15 min of recovery. Plasma concentrations of (R)- and (S)-carvedilol were determined by HPLC. RESULTS: Plasma concentrations of (R)-carvedilol were 2- to 3-fold higher than those of (S)-carvedilol (p < 0.05 in all cases). Plasma concentrations of both (R)- and (S)-carvedilol remained unaffected during exercise and recovery. CONCLUSIONS: Contrary to all other beta-blockers so far investigated, exercise had no effect on plasma concentrations of (R)- and (S)-carvedilol. We conclude that neither (R)- nor (S)-carvedilol is released from adrenergic cells during exercise, a feature that clearly distinguishes carvedilol from other beta-blockers. Thus, the human organism appears to handle (R)- and (S)-carvedilol differently than other beta-adrenoceptor antagonists. This finding deserves further investigation on a molecular and cellular level in order to clarify these differences between the pharmacokinetics of carvedilol and other beta-blockers.

Administration, Oral↗