Biomedical subjects

M Leibig

Publications and source records attributed to M Leibig.

9 recordsLinked to original sources

PubMed2005

Early time course of neointima formation and vascular remodelling following percutaneous coronary intervention and vascular brachytherapy of in-stent restenotic lesions as assessed by intravascular ultrasound analysis.

In-stent restenosis (ISR) represents the major limitation of stent implantation. Treatment, although of relative technical ease, is unsatisfactory due to a high incidence of recurrent restenosis. Vascular brachytherapy (VBT) has emerged as a powerful adjunct therapeutic modality to treat ISR. Inhibition of neointima formation has been regarded as the relevant mechanism of action. Yet, positive remodelling has been suspected as another contributing factor. Since only very few precise analyses of the extent, distribution and time course of the respective mechanims exist, the goal of the present study was to describe the changes of the vessel geometry at the target lesion and at the reference site following angioplasty and VBT of ISR in 42 patients by means of quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS) before and after the index procedure and at the 3 and 6 month follow-up. By QCA the acute lumen gain measured 2.2+/-0.8 mm, the late lumen loss at 3 months was 0.1+/-0.5 mm and at 6 months 0.4+/-0.7 mm. By IVUS luminal cross-sectional area increased from 1.5+/-1.2 mm(2) to 7.9+/-1.9 mm(2) (p<0.001). The intima hyperplasia cross-sectional area at 3 months was only 0.2+/-1.0 mm(2) (p=0.191), but increased to 0.7+/-0.6 mm(2) (p<0.001) at 6 months resulting in a lumen cross-sectional area of 7.1+/-1.7 mm(2). Stent dimensions did not show any significant changes over time. The external elastic membrane cross-sectional area at 3 months increased by 1.3+/-1.9 mm(2) (p<0.001), and showed a further increase by 0.7+/-2.9 mm(2) at 6 months. Positive remodelling could be demonstrated also at the reference segment. In conclusion the absolute amount of intima hyperplasia during a 6-month follow-up period after VBT of ISR is low and most pronounced between the third and sixth month. Besides this, predominantly within the first 3 months of follow-up, significant positive remodelling could be demonstrated at the target lesion and at the reference site. Both observed effects may contribute to the preservation of the vessel lumen.

Angioplasty, Balloon, Coronary↗

PubMed2005

Fractional flow reserve for the prediction of cardiac events after coronary stent implantation: results of a multivariate analysis.

OBJECTIVE: To determine the prognostic value of fractional flow reserve (FFR) measurements after coronary stent implantation including multiple clinical and angiographic parameters collected in one centre. METHODS: 119 consecutive patients were enrolled who had a stent implanted with the use of a pressure wire as a guidewire. Patients were followed up for at least six months. Any death, myocardial infarction, and target vessel revascularisation were considered major adverse cardiac events (MACE). Multivariate logistic regression was used to determine adjusted odds ratios (OR) and 95% confidence intervals (CI) for FFR and covariates. RESULTS: Complete follow up data were available for all 119 patients. Pre-interventional FFR increased from 0.65 (0.15) to 0.94 (0.06) (p < 0.0001) after stent implantation. Eighteen MACE (15%) occurred during follow up including 15 (12.6%) target vessel revascularisations. Final FFR was significantly higher in patients without than in patients with an event (0.95 (0.05) v 0.88 (0.08), p = 0.001). In the multivariate logistic regression analysis, only final FFR < 0.95 (OR 6.22, 95% CI 1.79 to 21.62, p = 0.004) and reduced left ventricular function (OR 0.95, 95% CI 092 to 0.99, p = 0.021) remained as significant independent predictors for MACE. CONCLUSION: These results including multiple parameters underline that FFR after coronary stenting is a strong and independent predictor for subsequent cardiac events after six months' follow up.

Coronary Angiography↗

PubMed2003

A randomized comparison of 4 doses of intracoronary adenosine in the assessment of fractional flow reserve.

BACKGROUND: Fractional flow reserve (FFR) is a measure of coronary stenosis severity that is based on pressure measurements obtained at maximal hyperemia. Therefore, achievement of maximal vasodilatation of the coronary microcirculation is a prerequisite for the measurement of FFR. The study was designed to address the hypothesis that intracoronary adenosine yields more complete vasodilatation of the coronary microcirculation when high doses are used, resulting in a more accurate FFR measurement. METHODS: Thirty-six patients with 43 moderate lesions underwent determination of FFR during cardiac catheterization. FFR was calculated in all lesions as the ratio of the distal coronary pressure to the aortic pressure at hyperemia. Different incremental doses of intracoronary adenosine (16, 24, 32 and 40 microg for both coronary arteries) were administered in a randomized fashion. RESULTS: No adverse events occurred with any intracoronary adenosine bolus. At baseline there were no significant differences for mean aortic and distal coronary pressure, heart rate as well as FFR values between the different doses. FFR was not significantly altered from the different incremental adenosine doses. However, in 27 (63%) out of 43 lesions there was a further reduction of FFR up to 0.23 when a dose >16 microg was injected. CONCLUSIONS: This study suggests that doses of adenosine up to 40 microg are safe and can be used to achieve a more pronounced vasodilatation in individual patients compared to the standard doses. This may have therapeutic impact with FFR values near cut-off points in patients undergoing diagnostic coronary angiography as well as in patients in whom FFR is used to assess the outcome of interventions.

Adenosine↗

PubMed1996

Low energy intracardiac cardioversion after failed conventional external cardioversion of atrial fibrillation.

OBJECTIVES: This study was designed to evaluate the efficacy of intracardiac cardioversion in patients with chronic atrial fibrillation after unsuccessful external cardioversion. BACKGROUND: Previous studies in patients with atrial fibrillation undergoing intracardiac cardioversion have suggested that intracardiac cardioversion is highly effective and safe. However, the characteristics of patients who benefit most from this invasive technique are unknown. METHODS: We prospectively studied 25 consecutive patients with chronic atrial fibrillation (11 +/- 9 months). All patients had undergone at least three attempts at conventional external transthoracic cardioversion by means of paddles in an anteroposterolateral position applying energies up to 360 J without success. Intracardiac shocks were delivered by an external defibrillator through defibrillation electrodes placed in the right atrium and coronary sinus or in the right atrium and left pulmonary artery. After conversion, all patients were treated orally with sotalol (mean 194 +/- 63 mg/day). RESULTS: Internal cardioversion was successful in 22 of 25 patients at a mean defibrillation threshold of 6.5 +/- 3.0 J. Mean lead impedance was 56.4 +/- 7.4 omega. No severe complications were observed. At a mean follow-up of 15 +/- 12 months, 12 (55%) of the patients treated successfully remained in sinus rhythm. CONCLUSIONS: In patients with failed external cardioversion, internal cardioversion offers a new option for restoring sinus rhythm. Intracardiac cardioversion is an effective and safe method and can be easily performed in patients with minimal sedation.

Adult↗

PubMed1994