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Biomedical subjects

Bernhard Meier

Publications and source records attributed to Bernhard Meier.

At least 55 records · Page 3Linked to original sources
PubMed2004

Reciprocal relationship between left ventricular filling pressure and the recruitable human coronary collateral circulation.

AIMS: The aim of our study in patients with coronary artery disease (CAD) and present, or absent, myocardial ischaemia during coronary occlusion was to test whether (i) left ventricular (LV) filling pressure is influenced by the collateral circulation and, on the other hand, that (ii) its resistance to flow is directly associated with LV filling pressure. METHODS AND RESULTS: In 50 patients with CAD, the following parameters were obtained before and during a 60 s balloon occlusion: LV, aortic (Pao) and coronary pressure (Poccl), flow velocity (Voccl), central venous pressure (CVP), and coronary flow velocity after coronary angioplasty (V(Ø-occl)). The following variables were determined and analysed at 10 s intervals during occlusion, and at 60 s of occlusion: LV end-diastolic pressure (LVEDP), velocity-derived (CFIv) and pressure-derived collateral flow index (CFIp), coronary collateral (Rcoll), and peripheral resistance index to flow (Rperiph). Patients with ECG signs of ischaemia during coronary occlusion (insufficient collaterals, n = 33) had higher values of LVEDP over the entire course of occlusion than those without ECG signs of ischaemia during occlusion (sufficient collaterals, n = 17). Despite no ischaemia in the latter, there was an increase in LVEDP from 20 to 60 s of occlusion. In patients with insufficient collaterals, CFIv decreased and CFIp increased during occlusion. Beyond an occlusive LVEDP > 27 mmHg, Rcoll and Rperiph increased as a function of LVEDP. CONCLUSION: Recruitable collaterals are reciprocally tied to LV filling pressure during occlusion. If poorly developed, they affect it via myocardial ischaemia; if well grown, LV filling pressure still increases gradually during occlusion despite the absence of ischaemia indicating transmission of collateral perfusion pressure to the LV. With low, but not high, collateral flow, resistance to collateral as well as coronary peripheral flow is related to LV filling pressure in the high range.

Aged↗
PubMed2004

Comparison of medical treatment with percutaneous closure of patent foramen ovale in patients with cryptogenic stroke.

OBJECTIVES: The purpose of this study was to compare the efficacy of medical treatment with percutaneous closure of patent foramen ovale (PFO). BACKGROUND: Patients with cryptogenic stroke and PFO are at risk for recurrent cerebrovascular events. METHODS: We compared the risk of recurrence in 308 patients with cryptogenic stroke and PFO, who were treated either medically (158 patients) or underwent percutaneous PFO closure (150 patients) between 1994 and 2000. RESULTS: Patients undergoing percutaneous PFO closure had a larger right-to-left shunt (p < 0.001; 95% confidence interval [CI] 1.38 to 3.07) and were more likely to have suffered more than one cerebrovascular event (p = 0.03; 95% CI 1.04 to 2.71). At four years of follow-up, percutaneous PFO closure resulted in a non-significant trend toward risk reduction of death, stroke, or transient ischemic attack (TIA) combined (8.5% vs. 24.3%; p = 0.05; 95% CI 0.23 to 1.01), and of recurrent stroke or TIA (7.8% vs. 22.2%; p = 0.08; 95% CI 0.23 to 1.11) compared with medical treatment. Patients with more than one cerebrovascular event at baseline and those with complete occlusion of PFO were at lower risk for recurrent stroke or TIA after percutaneous PFO closure compared with medically treated patients (7.3% vs. 33.2%; p = 0.01; 95% CI 0.08 to 0.81, and 6.5% vs. 22.2%; p = 0.04; 95% CI 0.14 to 0.99, respectively). CONCLUSIONS: Percutaneous PFO closure appears at least as effective as medical treatment for prevention of recurrent cerebrovascular events in cryptogenic stroke patients with PFO. It might be more effective than medical treatment in patients with complete closure and more than one cerebrovascular event.

Adolescent↗
PubMed2004

Deleterious effect of coronary brachytherapy on vasomotor response to exercise.

BACKGROUND: Intracoronary radiotherapy (brachytherapy) has been proposed as treatment option for in-stent restenosis. Long-term results of brachytherapy with regard to vascular integrity and vasomotor responsiveness are unknown. The purpose of the present study was to determine the vasomotor response after brachytherapy and to assess its influence on vasomotion during exercise. METHODS AND RESULTS: Biplane quantitative coronary angiography was performed at rest and during bicycle exercise in 27 patients with coronary artery disease. Fourteen patients underwent coronary stenting and were studied 10+/-3 months after intervention (control group). Thirteen patients were treated with brachytherapy (Guidant Galileo System) for in-stent restenosis with a mean dosis of 20 Gy at 1 mm into the vessel wall and were studied 9+/-1 months after radiation (brachytherapy group). Minimal luminal area, stent area, and proximal, distal, and a reference vessel area were determined. The reference vessel showed exercise-induced vasodilation (26+/-4%, P<0.001) in both groups. Vasomotion within the stented vessel segments was abolished. In control subjects, the proximal and distal segments showed exercise-induced vasodilation (17+/-2% and 22+/-7%, respectively; P<0.005). In contrast, there was exercise-induced vasoconstriction in the proximal and distal vessel segments of the brachytherapy group (-14+/-3% and -16+/-4%, respectively; P<0.01). Sublingual nitroglycerin was associated with maximal vasodilation of the proximal and distal vessel segments in both groups. CONCLUSIONS: Normal vessel segments elicit flow-mediated vasodilation during exercise. Stent implantation does not affect physiological response to exercise proximal and distal to the stent. Brachytherapy eliminates exercise-induced vasodilation, although dilatory response to nitroglycerin is maintained, suggesting endothelial dysfunction as the underlying mechanism.

Aged↗
PubMed2004

Implantation of a second closure device in patients with residual shunt after percutaneous closure of patent foramen ovale.

Percutaneous closure of patent foramen ovale (PFO) in patients with presumed paradoxical embolism yields complete occlusion in > 90% of patients using contemporary closure devices. Patients with a residual shunt after percutaneous PFO closure have been found at increased risk for recurrent paradoxical events. Treatment options for such patients include medical treatment using antiplatelet drugs or oral anticoagulation, surgical device removal and patch closure, and percutaneous implantation of a second closure device. We report our experience with implantation of a second closure device in 10 patients with more than a minimal residual shunt < or = 6 months after percutaneous PFO closure. Procedure and fluoroscopy times were similar for the initial and repeat intervention (32 vs. 30 min and 5 vs. 6 min, respectively; P = NS). There were no procedural complications during implantation of the second closure device. Follow-up transesophageal echocardiography 6 months after the second percutaneous intervention revealed complete PFO closure in nine (90%) patients. Therefore, implantation of a second closure device in patients with persistence of more than a residual shunt after percutaneous PFO closure appears safe and effective.

Adult↗
PubMed2004

Coronary collateral perfusion in patients with coronary artery disease: effect of metoprolol.

BACKGROUND: The use of ultrathin Doppler angioplasty guidewires has made it possible to measure collateral flow quantitatively. Pharmacologic interventions have been shown to influence collateral flow and, thus, to affect myocardial ischaemia. METHODS: Twenty-five patients with coronary artery disease undergoing PTCA were included in the present analysis. Coronary flow velocities were measured in the ipsilateral (n = 25) and contralateral (n = 6; two Doppler wires) vessels during PTCA with and without i.v. adenosine (140 microg/kg.min) before and 3 min after 5 mg metoprolol i.v., respectively. The ipsilateral Doppler wire was positioned distal to the stenosis, whereas the distal end of the contralateral wire was in an angiographically normal vessel. The flow signals of the ipsilateral wire were used to calculate the collateral flow index (CFI). CFI was defined as the ratio of flow velocity during balloon inflation divided by resting flow. RESULTS: Heart rate and mean aortic pressure decreased slightly (ns) after i.v. metoprolol. The collateral flow index was 0.25+/-0.12 (one fourth of the resting coronary flow) during the first PTCA and 0.27+/-0.14 (ns versus first PTCA) during the second PTCA, but decreased with metoprolol to 0.16+/-0.08 (p<0.0001 vs. baseline) during the third PTCA. CONCLUSIONS: Coronary collateral flow increased slightly but not significantly during maximal vasodilatation with adenosine but decreased in 23 of 25 patients after i.v. metoprolol. Thus, there is a reduction in coronary collateral flow with metoprolol, probably due to an increase in coronary collateral resistance or a reduction in oxygen demand.

Adolescent↗
PubMed2004

Percutaneous coronary interventions in Europe 1992-2001.

AIMS: The purpose of this registry is to collect data on trends in interventional cardiology within Europe. Special interest focuses on relative increases and ratios in newer re-vascularisation approaches and its distribution in different regions in Europe. We report the data of the year 2001 and give an overview of the development of coronary interventions since 1992, when the first data collection was performed. METHODS AND RESULTS: Questionnaires were distributed to delegates of the individual national societies of cardiology represented in the European Society of Cardiology. These were completed by the local institutions and operators and showed that 1,806,238 angiograms and 617,176 percutaneous transluminal coronary angioplasties (PTCAs) were performed in 2001. This is an increase of 10% and 17%, respectively, compared with the year 2000. The population-adjusted PTCA rate rose from nearly 800 procedures per 10(6) inhabitants in the year 2000 to approximately 990 procedures per 10(6) inhabitants in 2001. Coronary stenting increased by 25% to about 488,900 stents implanted in 2001. Complication rates remained unchanged, and the need for emergency coronary artery bypass grafting is still at 0.2% per percutaneous intervention. CONCLUSION: Interventional cardiology in Europe is still expanding, mainly due to rapid growth in countries with lower socio-economical levels. Most central European countries reported only minor increases in procedures performed. Coronary stenting remains the only noteworthy adjunctive strategy to balloon angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed2004

Impact of clopidogrel in coronary artery bypass grafting.

OBJECTIVE: Clopidogrel has become the standard of care to prevent thrombotic complications following cardiological interventions, in particular intracoronary stenting. In addition, patients with aspirin intolerance and those with carotid and peripheral vascular disease are also increasingly treated with clopidogrel. Platelet inhibition may become a concern for hemostasis in patients treated with clopidogrel who need emergency and undelayed surgery. METHODS: We prospectively analyzed the intra- and postoperative outcome of 505 consecutive patients who underwent isolated CABG and compared two groups: those with clopidogrel exposure until 72 h prior to surgery (n = 136) with those without exposition to clopidogrel (n = 369). Patients undergoing emergency surgery because of failed PTCA and cardiogenic shock, associated valvular surgery, redo-CABG, and those with additional platelet IIb/IIIa receptor inhibitor exposure were excluded. Patients who received aspirin and/or heparin treatment prior to surgery were not excluded. RESULTS: Patients who received clopidogrel had a higher prevalence of angina class III or IV (67 vs 39%, P < 0.01), received more often revascularization within 48 h (41 vs 14%, P = 0.02), and had received more frequently stenting (57 vs 13%). Chest tube drainage was significantly increased during the first 24 h following CABG in the group of patients who had clopidogrel treatment (1485 vs 780 ml, P = 0.003) These patients also required more transfusion of platelets and fresh frozen plasma. Overall re-exploration rate because of bleeding was significantly higher in the clopidogrel group (5.9 vs 1.2%, P < 0.01). Platelets transfused before chest closure had a beneficial effect on preservation of the hemostasis. CONCLUSIONS: Clopidogrel exposure 3 days or less prior to CABG surgery significantly increases the risk of postoperative bleeding, the need for perioperative transfusion and the incidence of re-exploration. Surgery should be performed using standard heparinization and anti-fibrinolytic strategies but aggressive correction of platelets dysfunction is required before chest closure.

Aged↗
PubMed2004

Clinical and angiographic results after mechanical connection for distal anastomosis in coronary surgery.

BACKGROUND: Sutureless anastomotic devices are of increasing interest in cardiovascular surgery. We investigated the stainless steel clip system of St Jude Medical/Anastomotic Technology Group (Maple Grove, Minn) to connect saphenous vein grafts with coronary arteries. METHODS: Forty-five patients were enrolled in this feasibility study performed on patients who had on-pump coronary artery bypass grafting, but 32 patients only received 1 distal anastomosis with this investigational device (2.5 mm [n = 14] and 2.0 mm [n = 18]). Thirteen were excluded because target vessels were too small, calcified, or tortuous. The system consists of an expandable clip mounted on a balloon catheter; delivery is obtained during balloon inflation. The main differences between the 2.5-mm and 2.0-mm devices are different loading and deployment in smaller coronary arteries for the 2.0-mm device. RESULTS: A connecting device was deployed on the right coronary artery in 14 patients, the posterior descending branch in 12 patients, the obtuse marginal in 5 patients, and the posterolateral branch in 1 patient. Perfect hemostasis of the sutureless connector anastomosis was obtained in 28 patients. Three connectors were removed because of minor leakage at the connection site, and 1 connector was removed because of mismanipulation after successful deployment. Hand-sewn anastomosis was performed at the same arteriotomy site. Intraoperative flow was assessed by the transit time method and averaged 71 +/- 24 mL/min. One patient died of neurologic injury; the connector was patent at autopsy. One patient had a perioperative myocardial infarction. There was no adverse cardiac event in the remaining patients. All patients underwent clinical follow-up after 6 and 12 months and 35 angiograms were available in 21 patients: after 3 and 6 months, 17 anastomoses were patent and the saphenous vein graft was occluded in 4 patients. CONCLUSIONS: The coronary connector system from St Jude Medical/Anastomotic Technology Group allows consistently uniform sutureless connection between the saphenous vein graft and coronary artery. Loading and deployment require careful training. This technology is under constant development and may give a significant boost to less invasive coronary revascularization techniques.

Aged↗
PubMed2003

Early exercise after coronary stenting is safe.

OBJECTIVES: In this study, we sought to assess safety of symptom-limited exercise stress tests the day after coronary stenting. BACKGROUND: Isolated cases of coronary stent thrombosis have been linked to early exercise stress testing, thereby questioning the safety of unrestricted physical activity after the coronary procedure. METHODS: At a single center, 1,000 patients were randomized to a symptom-limited stress test the day after coronary stenting or no stress test. The antiplatelet regimen consisted of acetylsalicylic acid and postprocedural ticlopidine or clopidogrel. The primary end point of the study was the incidence of clinical stent thrombosis at 14 days. The secondary end point was the occurrence of access site complications. RESULTS: Clinical stent thrombosis occurred in five patients (1%) undergoing stress test and in five patients (1%) randomized to no stress test (p = 1.0). Access site complications were detected in 4% and 5.2% of cases, respectively (p = 0.37). CONCLUSIONS: Symptom-limited exercise stress testing the day after coronary stenting does not increase the risk of clinical stent thrombosis or access site complications. Further investigations on safety of early vigorous exercise after coronary stenting in a non-supervised setting are warranted.

Aged↗
PubMed2003

Effect of abciximab versus tirofiban on activated clotting time during percutaneous intervention and its relation to clinical outcomes--observations from the TARGET trial.

Previous evidence suggests that the monoclonal antibody abciximab may have a more potent anticoagulant effect than small-molecule glycoprotein (GP) IIb/IIIa inhibitors. We prospectively reviewed collected heparin dose, activated clotting time (ACT), and corresponding clinical outcome data from The Do Tirofiban and ReoPro Give Similar Efficacy Outcome Trial (TARGET), a direct comparison of tirofiban versus abciximab in patients who underwent percutaneous intervention. Of the 4,809 patients enrolled in the trial, 3,739 patients (78%) had an ACT measured after the administration of GP IIb/IIIa and heparin (peak procedural ACT); this formed the population for the present study. Mean total heparin dose was 75 +/- 32 and 76 +/- 31 U/kg in the tirofiban and abciximab groups, respectively. The resultant mean peak ACTs were 296 +/- 91 and 299 +/- 89 seconds (p = 0.09). In a subset of patients with both baseline ACT (before any heparin or GP IIb/IIIa therapy) and peak procedural ACT measurements, the difference in ACT between these time points was 80 +/- 97 vs 82 +/- 101 seconds (p = 0.44) for the tirofiban and abciximab groups, respectively. After adjusting for patients' weight, weight-adjusted heparin dose, and method of ACT measurement in a multiple linear regression analysis, the type of GP IIb/IIIa inhibitor was not predictive of the peak ACT (p = 0.24). When stratified by ACT quartile, no statistically significant difference in bleeding or ischemic end points between the tirofiban and abciximab cohorts was observed. In this large contemporary percutaneous coronary intervention trial, there was no observed difference in the anticoagulant effect of tirofiban and abciximab, as measured by the ACT, or in the incidence of bleeding or ischemic complications in each ACT quartile.

Abciximab↗
PubMed2003

Is there functional collateral flow during vascular occlusion in angiographically normal coronary arteries?

BACKGROUND: Thus far, it is unknown whether there is functional collateral flow through preexisting anastomoses in patients with angiographically normal coronary arteries. Such preformed coronary collateral vessels could form the basis for subsequently developing protective natural bypasses in the presence of coronary artery disease. METHODS AND RESULTS: Among 100 patients, the collateral flow index (CFI) was measured in coronary arteries without stenotic lesions. The CFI was determined by simultaneous measurement of mean aortic pressure, central venous pressure, and coronary wedge pressure via a sensor-tipped guidewire at the end of a 1-minute balloon occlusion. Patients were divided in 2 groups according to complete angiographic absence (51 patients) or partial presence (49 patients) of stenotic lesions in coronary arteries other than that undergoing collateral measurement. CFI in all patients (61+/-10 years; men/women, 69/31) amounted to 0.18+/-0.08 (range, 0.04 to 0.36). It showed a normal Gaussian frequency distribution; 22 individuals had a CFI > or =0.25, a value that was empirically found to represent well-developed collaterals protective against myocardial ischemia during coronary occlusion. Accordingly, 17 patients did not reveal signs of myocardial ischemia during coronary balloon occlusion, as assessed from an intracoronary ECG, and 26 patients did not experience angina pectoris during occlusion. CONCLUSIONS: In humans with angiographically normal coronary arteries, there are functional collateral vessels to the extent that one fifth to one quarter of them do not show signs of myocardial ischemia during brief vascular occlusions.

Angioplasty, Balloon, Coronary↗
PubMed2003

Low pro-brain natriuretic peptide levels predict benign clinical outcome in acute pulmonary embolism.

BACKGROUND: The role of pro-brain natriuretic peptide (proBNP) for the prediction of clinical outcome has not been examined in patients with acute pulmonary embolism (PE). METHODS AND RESULTS: ProBNP levels were measured in 73 patients with acute PE within 4 hours of admission. Adverse clinical outcome was defined as in-hospital death or the need for at least 1 of the following: cardiopulmonary resuscitation, mechanical ventilation, pressors, thrombolysis, catheter fragmentation, or surgical embolectomy. In the 53 patients with a benign clinical outcome, proBNP (median 121, range 16 to 34 802 pg/mL) was lower than in 20 patients with adverse clinical outcome (median 4250, range 92 to 49 607 pg/mL; P<0.0001). The negative predictive value of proBNP levels <500 pg/mL to predict adverse clinical outcome was 97% (95% confidence interval 84 to 99). ProBNP remained an independent predictor for adverse clinical outcome (odds ratio 14.6; 95% confidence interval 1.5 to 139.0; P=0.02) after adjusting for severity of PE (submassive/massive), troponin T levels >0.01 ng/mL, age >70 years, gender, and history of congestive heart failure. CONCLUSIONS: Low proBNP levels predict an uneventful hospital course in patients with acute PE. A proBNP level <500 pg/mL identifies patients who will be potential candidates for an abbreviated hospital length of stay or care on a completely outpatient basis.

Acute Disease↗