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Biomedical subjects

Bernhard Meier

Publications and source records attributed to Bernhard Meier.

At least 37 records · Page 2Linked to original sources
PubMed2005

Collateral-flow measurements in humans by myocardial contrast echocardiography: validation of coronary pressure-derived collateral-flow assessment.

AIMS: Myocardial blood flow (MBF) is the gold standard to assess myocardial blood supply and, as recently shown, can be obtained by myocardial contrast echocardiography (MCE). The aims of this human study are (i) to test whether measurements of collateral-derived MBF by MCE are feasible during elective angioplasty and (ii) to validate the concept of pressure-derived collateral-flow assessment. METHODS AND RESULTS: Thirty patients with stable coronary artery disease underwent MCE of the collateral-receiving territory during and after angioplasty of 37 stenoses. MCE perfusion analysis was successful in 32 cases. MBF during and after angioplasty varied between 0.060-0.876 mL min(-1) g(-1) (0.304+/-0.196 mL min(-1) g(-1)) and 0.676-1.773 mL min(-1) g(-1) (1.207+/-0.327 mL min(-1) g(-1)), respectively. Collateral-perfusion index (CPI) is defined as the rate of MBF during and after angioplasty varied between 0.05 and 0.67 (0.26+/-0.15). During angioplasty, simultaneous measurements of mean aortic pressure, coronary wedge pressure, and central venous pressure determined the pressure-derived collateral-flow index (CFI(p)), which varied between 0.04 and 0.61 (0.23+/-0.14). Linear-regression analysis demonstrated an excellent agreement between CFI(p) and CPI (y=0.88 x +0.01; r(2)=0.92; P<0.0001). CONCLUSION: Collateral-derived MBF measurements by MCE during angioplasty are feasible and proved that the pressure-derived CFI exactly reflects collateral relative to normal myocardial perfusion in humans.

Blood Flow Velocity↗
PubMed2005

Sirolimus-eluting and paclitaxel-eluting stents for coronary revascularization.

BACKGROUND: Sirolimus-eluting stents and paclitaxel-eluting stents, as compared with bare-metal stents, reduce the risk of restenosis. It is unclear whether there are differences in safety and efficacy between the two types of drug-eluting stents. METHODS: We conducted a randomized, controlled, single-blind trial comparing sirolimus-eluting stents with paclitaxel-eluting stents in 1012 patients undergoing percutaneous coronary intervention. The primary end point was a composite of major adverse cardiac events (death from cardiac causes, myocardial infarction, and ischemia-driven revascularization of the target lesion) by nine months. Follow-up angiography was completed in 540 of 1012 patients (53.4 percent). RESULTS: The two groups had similar baseline clinical and angiographic characteristics. The rate of major adverse cardiac events at nine months was 6.2 percent in the sirolimus-stent group and 10.8 percent in the paclitaxel-stent group (hazard ratio, 0.56; 95 percent confidence interval, 0.36 to 0.86; P=0.009). The difference was driven by a lower rate of target-lesion revascularization in the sirolimus-stent group than in the paclitaxel-stent group (4.8 percent vs. 8.3 percent; hazard ratio, 0.56; 95 percent confidence interval, 0.34 to 0.93; P=0.03). Rates of death from cardiac causes were 0.6 percent in the sirolimus-stent group and 1.6 percent in the paclitaxel-stent group (P=0.15); the rates of myocardial infarction were 2.8 percent and 3.5 percent, respectively (P=0.49); and the rates of angiographic restenosis were 6.6 percent and 11.7 percent, respectively (P=0.02). CONCLUSIONS: As compared with paclitaxel-eluting stents, the use of sirolimus-eluting stents results in fewer major adverse cardiac events, primarily by decreasing the rates of clinical and angiographic restenosis.

Angioplasty, Balloon, Coronary↗
PubMed2005

Sirolimus-eluting stents associated with paradoxic coronary vasoconstriction.

OBJECTIVES: The purpose of the present study was to assess coronary vasomotor response to exercise after sirolimus-eluting stent (SES) implantation. BACKGROUND: Sirolimus-eluting stents have been shown to markedly reduce the incidence of angiographic and clinical restenosis. However, long-term effects of sirolimus on endothelial function are unknown. METHODS: Coronary vasomotion was evaluated with biplane quantitative coronary angiography at rest and during supine bicycle exercise in 25 patients with coronary artery disease. Eleven patients were treated with a bare-metal stent (BMS) (control group) and 14 patients underwent SES implantation (sirolimus group) for de novo coronary artery lesions. Both groups were studied 6 +/- 1 month after the intervention. Minimal luminal diameter; stent diameter; and proximal, distal, and reference vessel diameter were determined. RESULTS: The reference vessel showed exercise-induced vasodilation (+13 +/- 4%) in both groups. Vasomotion within the stented vessel segments was abolished. In controls, the adjacent segments proximal and distal to the stent showed exercise-induced vasodilation (+15 +/- 3% and +17 +/- 4%, respectively). In contrast, there was exercise-induced vasoconstriction of the proximal and distal vessel segments adjacent to SESs (-12 +/- 4% and -15 +/- 6%, respectively; p < 0.001 vs. corresponding segments of controls). Sublingual nitroglycerin was associated with maximal vasodilation of the proximal and distal vessel segments in both groups. CONCLUSIONS: Implantation of a BMS does not affect physiologic response to exercise proximal and distal to the stent. However, SESs are associated with exercise-induced paradoxic coronary vasoconstriction of the adjacent vessel segments, although vasodilatory response to nitroglycerin is maintained. These observations suggest (drug-induced) endothelial dysfunction as the underlying mechanism.

Case-Control Studies↗
PubMed2005

Mean platelet volume on admission predicts impaired reperfusion and long-term mortality in acute myocardial infarction treated with primary percutaneous coronary intervention.

OBJECTIVES: We sought to determine the prognostic value of mean platelet volume (MPV) for angiographic reperfusion and six-month mortality in patients with acute ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI). BACKGROUND: Mean platelet volume is predictive of unfavorable outcome among survivors of STEMI when measured after the index event. No data are available for the value of admission MPV in patients with STEMI treated with primary PCI. METHODS: Blood samples for MPV estimation, obtained on admission in 398 consecutive patients presenting with STEMI, were measured before primary PCI. Follow-up up to six months was performed. RESULTS: No-reflow was significantly more frequent in patients with high MPV (> or =10.3 fl) compared with those with low MPV (<10.3 fl) (21.2% vs. 5.5%, p < 0.0001). The MPV was correlated strongly with corrected Thrombolysis In Myocardial Infarction frame count (CTFC) (r = 0.698, p < 0.0001). Kaplan-Meier survival analysis showed six-month mortality rate of 12.1% in patients with high MPV versus 5.1% in low MPV group (log rank = 6.235, p = 0.0125). After adjusting for baseline characteristics, high MPV remained a strong independent predictor of no-reflow (odds ratio [OR] 4.7, 95% confidence interval [CI] 2.3 to 9.9, p < 0.0001), CTFC > or =40 (OR 10.1, 95% CI 5.7 to 18.1, p < 0.0001), and mortality (OR 3.2, 95% CI 1.1 to 9.3, p = 0.0084). Abciximab administration resulted in significant mortality reduction only in patients with high MPV values (OR 0.02, 95% CI 0.01 to 0.48, p = 0.0165). CONCLUSIONS: Mean platelet volume is a strong, independent predictor of impaired angiographic reperfusion and six-month mortality in STEMI treated with primary PCI. Apart from prognostic value, admission MPV may also carry further practical, therapeutic implications.

Abciximab↗
PubMed2005

Percutaneous catheter thrombectomy device for acute pulmonary embolism: in vitro and in vivo testing.

PURPOSE: To evaluate a percutaneous pulmonary embolism (PE) thrombectomy catheter that aspirates, macerates, and removes thrombus. MATERIALS AND METHODS: Nine in vitro tests were performed by using porcine thrombi at a PE test station that provides continuous fluid output of 2 L/min at a pressure of 50 mmHg. Macroembolization was defined as embolized particles larger than 1.5 mm in dimension; microembolization was defined as particles that range in size from 0.1 to 1.5 mm. In static in vitro tests, researchers measured plasma-free hemoglobin levels in a 36-year-old man to assess mechanical hemolysis. Investigational review board approval and informed consent were obtained. The Department of Agriculture, Veterinary Bureau, Bern, Switzerland approved in vivo tests. Researchers investigated device effectiveness in 10 pigs that developed cardiogenic shock but survived massive PE after injection of two or three porcine thrombi into the external jugular vein via a surgically implanted 24-F sheath. Pulmonary angiography and hemodynamic measurements, including mean aortic and mean pulmonary artery pressure, heart rate, and mixed venous oxygen saturation, were obtained at baseline, after embolization, and after thrombectomy. Repeated-measures analysis of variance was performed to compare hemodynamic measurements at baseline, after embolization, and after thrombectomy. Cardiovascular structures were examined at necropsy for rupture, perforation, dissection, or hemorrhage. RESULTS: During a mean aspiration time of 69 seconds +/- 19, thrombi were completely extracted from 14-mm test tubes, with an aspirated fluid volume of 201 mL +/- 64. Although no macroembolization was observed, microembolization was quantified at 1.9 g +/- 1.3. Catheter aspiration was not associated with an increase in plasma-free hemoglobin. In 10 animals, aortic pressure increased from 52 mmHg +/- 24 before thrombectomy to 90 mmHg +/- 32 after thrombectomy, mixed venous oxygen saturation increased from 48% +/- 19% to 61% +/- 12%, pulmonary artery pressure decreased from 33 mmHg +/- 9 to 22 mmHg +/- 4, and heart rate decreased from 162 beats per minute +/- 24 to 114 beats per minute +/- 14. We did not observe macro- or microscopic damage to treated or untreated cardiovascular structures. CONCLUSION: The PE thrombectomy device was highly effective, facilitating rapid reversal of cardiogenic shock without device-related complications.

Acute Disease↗
PubMed2005

Percutaneous left atrial appendage transcatheter occlusion (PLAATO system) to prevent stroke in high-risk patients with non-rheumatic atrial fibrillation: results from the international multi-center feasibility trials.

OBJECTIVES: These studies were conducted to evaluate the feasibility of percutaneous left atrial appendage (LAA) occlusion using the PLAATO system (ev3 Inc., Plymouth, Minnesota). BACKGROUND: Patients with atrial fibrillation (AF) have a five-fold increased risk for stroke. Other studies have shown that more than 90% of atrial thrombi in patients with non-rheumatic AF originate in the LAA. Transvenous closure of the LAA is a new approach in preventing embolism in these patients. METHODS: Within two prospective, multi-center trials, LAA occlusion was attempted in 111 patients (age 71 +/- 9 years). All patients had a contraindication for anticoagulation therapy and at least one additional risk factor for stroke. The primary end point was incidence of major adverse events (MAEs), a composite of stroke, cardiac or neurological death, myocardial infarction, and requirement for procedure-related cardiovascular surgery within the first month. RESULTS: Implantation was successful in 108 of 111 patients (97.3%, 95% confidence interval [CI] 92.3% to 99.4%) who underwent 113 procedures. One patient (0.9%, 95% CI 0.02% to 4.9%) experienced two MAEs within the first 30 days: need for cardiovascular surgery and in-hospital neurological death. Three other patients underwent in-hospital pericardiocentesis due to a hemopericardium. Average follow-up was 9.8 months. Two patients experienced stroke. No migration or mobile thrombus was noted on transesophageal echocardiogram at one and six months after device implantation. CONCLUSIONS: Closing the LAA using the PLAATO system is feasible and can be performed at acceptable risk. It may become an alternative in patients with AF and a contraindication for lifelong anticoagulation treatment.

Aged↗
PubMed2005

Percutaneous coronary interventions in Europe 2000.

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 revascularization approaches and its distribution in different regions in Europe. METHODS AND RESULTS: Questionnaires distributed to delegates of the national societies of cardiology represented in the European Society of Cardiology to be completed by local institutions and operators yielded that 1637148 angiograms and 525983 coronary angioplasty (PTCAs) were performed in 2000. This is an increase of 15% and 23%, respectively, compared with 1999, particularly due to increases in eastern European countries. The population-adjusted PTCA rate rose from 714 procedures per 10(6) inhabitants in 1999 to approximately 800 procedures per 10(6) inhabitants in the year 2000. Coronary stenting increased by 26% to about 395000 stented cases in 2000. Complication rates remained unchanged, the need for emergency coronary artery bypass grafting (CABG) further decreased to 0.2% per percutaneous intervention. CONCLUSION: Interventional cardiology in Europe is still expanding, mainly due to rapid growth in countries with lower socioeconomical levels. Most central European countries reported only minor increases in procedures performed. Coronary stenting remains the only noteworthy adjunctive or alternative strategy to balloon angioplasty.

Cardiac Catheterization↗
PubMed2005

Stent thrombosis is associated with an impaired response to antiplatelet therapy.

OBJECTIVES: We sought to evaluate the response to antiplatelet therapy in patients with stent thrombosis (ST). BACKGROUND: Stent thrombosis is associated with considerable morbidity and mortality. An impaired response to antiplatelet therapy might be related to an increased risk for ST. METHODS: Eighty-two patients were included in the present study: 23 patients with previous ST, 50 matched controls (coronary stenting without ST), and 9 healthy volunteers. Platelet aggregation (PA) was studied (optical aggregometry) under monotherapy with acetylsalicylic acid (ASA) 100 mg daily for one month, followed by dual therapy with ASA 100 mg and clopidogrel 75 mg daily (loading dose 300 mg) for another month. RESULTS: Maximal (5 and 20 micromol) adenosine diphosphate-induced PA was significantly higher in patients with ST compared with controls (5 micromol, p < 0.005; 20 micromol, p < 0.05) and volunteers (5 micromol, p < 0.005; 20 micromol, p < 0.05). Resistance to ASA (>20% aggregation with 0.5 mg/ml arachidonic acid) was more prevalent in patients with ST (48%) compared with control patients (32%, p = ns) and volunteers (0%, p = 0.01). Clopidogrel significantly reduced PA in all three groups, but intergroup differences persisted. Clopidogrel resistance (<10% relative change) was similar in patients with ST, control patients, and volunteers (4%, 6%, and 11%, respectively, all p = NS). However, combined ASA and clopidogrel resistance was more prevalent in patients with ST (52%) compared with controls (38%, p = NS) and volunteers (11%, p < 0.05). CONCLUSIONS: Patients with previous ST show an impaired response to antiplatelet therapy with ASA compared with controls and volunteers. Additional treatment with clopidogrel is not able to overcome these differences in PA. Acetylsalicylic acid but not clopidogrel resistance appears to be associated with ST.

Aged↗
PubMed2005

Randomized comparison of a titanium-nitride-oxide-coated stent with a stainless steel stent for coronary revascularization: the TiNOX trial.

BACKGROUND: Stent coating with titanium-nitride-oxide has been shown to reduce neointimal hyperplasia in the porcine restenosis model. We designed a prospective, randomized, clinical study to investigate the safety and efficacy of titanium-nitride-oxide-coated stents compared with stainless steel stents. METHODS AND RESULTS: Ninety-two patients with de novo lesions were randomly assigned to treatment with titanium-nitride-oxide-coated stents (n=45) or stainless steel stents of otherwise identical design (n=47; control). Baseline characteristics were similar in both groups. At 30 days, no stent thromboses or other adverse events had occurred in either group. Quantitative coronary angiography at 6 months revealed lower late loss (0.55+/-0.63 versus 0.90+/-0.76 mm, P=0.03) and percent diameter stenosis (26+/-17% versus 36+/-24%, P=0.04) in lesions treated with titanium-nitride oxide-coated than in control stents. Binary restenosis was reduced from 33% in the control group to 15% in the titanium-nitride oxide-coated stent group (P=0.07). Intravascular ultrasound studies at 6 months showed smaller neointimal volume in titanium-nitride-oxide-coated stents than in control stents (18+/-21 versus 48+/-28 mm3, P<0.0001). Major adverse cardiac events at 6 months were less frequent in titanium-nitride-oxide-coated stents than in control stent-treated patients (7% versus 27%, P=0.02), largely driven by a reduced need for target-lesion revascularization (7% versus 23%, P=0.07). CONCLUSIONS: Revascularization with titanium-nitride-oxide-coated stents is safe and effective in patients with de novo native coronary artery lesions. Titanium-nitride-oxide-coated stents reduce restenosis and major adverse cardiac events compared with stainless steel stents of otherwise identical design.

Aged↗
PubMed2005

Stent thrombosis following bare-metal stent implantation: success of emergency percutaneous coronary intervention and predictors of adverse outcome.

AIMS: To investigate the efficacy and outcome of emergency percutaneous coronary interventions (PCI) in patients with stent thrombosis. METHODS AND RESULTS: Between 1995 and 2003, 6058 patients underwent bare-metal stent implantation, of which 95 (1.6%) patients suffered from stent thrombosis. The timing of stent thrombosis was acute in 10 (11%), subacute in 61 (64%), and late in 24 (25%) patients. Procedural and clinical outcomes of emergency PCI for treatment of stent thrombosis were investigated. Emergency PCI was successful in 86 (91%), complicated by death in 2 (2%), and coronary artery bypass grafting in 2 (2%) patients. Myocardial infarction occurred in 77 (81%) patients with a peak creatine kinase level of 1466+/-1570 U/L. Left ventricular ejection fraction declined from 0.54+/-0.19 prior to 0.48+/-0.16 (P<0.05) at the time of stent thrombosis after emergency PCI. A 6 month major adverse clinical events comprised death (11%), reinfarction (16%), and recurrent stent thrombosis (12%) after emergency PCI. Multivariable logistic regression analysis identified the achievement of TIMI 3 flow (OR=0.1, CI 95% 0.01-0.54, P<0.001) and diameter stenosis <50% (OR=0.06, CI 95% 0.01-0.32, P<0.001) during emergency PCI to be independently associated with a reduced risk of cardiac death. Recurrent stent thrombosis was independently predicted by the omission of abciximab (OR=4.3, CI 95% 1.1-17.5). CONCLUSION: Emergency PCI for treatment of stent thrombosis effectively restores vessel patency and flow. Patients presenting with stent thrombosis are at risk for recurrent myocardial infarction and recurrent stent thrombosis.

Abciximab↗
PubMed2005

Transcatheter treatment of atrial septal aneurysm associated with patent foramen ovale for prevention of recurrent paradoxical embolism in high-risk patients.

OBJECTIVES: This study sought to investigate the safety and efficacy of transcatheter treatment of atrial septal aneurysm (ASA) associated with patent foramen ovale (PFO). BACKGROUND: Patients with both ASA and PFO are at high risk for recurrent paradoxical embolism. METHODS: The procedural, echocardiographic, and clinical outcomes of 141 patients with ASA + PFO and > or =1 paradoxical embolic event undergoing transcatheter treatment were compared with 220 patients with PFO alone. RESULTS: Device success (ASA + PFO, 99.3%; PFO alone, 99.5%; p = 0.75) and procedural complications (ASA + PFO, 0.7%; PFO alone, 3.2%; p = 0.12) were similar in both groups. Maximal atrial septal excursion in patients with ASA + PFO decreased from 16 +/- 4 mm before to 4 +/- 3 mm after the intervention (p < 0.0001). At 6 months follow-up, right-to-left shunt was abolished in 120 (86%) patients with ASA + PFO, compared to 187 (85%) patients with PFO alone (p = 0.80). Freedom from recurrent transient ischemic attack, stroke, and peripheral embolism at 4 years was 95% (ASA + PFO) and 94% (PFO alone, p = 0.70), respectively. A residual right-to-left shunt after the intervention was the only predictor for recurrence (hazard ratio [HR] 6.9; 95% confidence interval [CI] 1.3 to 36.9, p < 0.03) in patients with ASA + PFO. CONCLUSIONS: Transcatheter treatment of ASA + PFO is safe and effective in patients with paradoxical embolism. The procedure effectively abolishes right-to-left shunt and decreases atrial septal mobility. Long-term prevention of recurrent events appears favorable when compared to patients with PFO alone.

Adult↗
PubMed2005

Tumour necrosis factor-alpha and interleukin-6 release during primary percutaneous coronary intervention for acute myocardial infarction is related to coronary collateral flow.

OBJECTIVES: We tested the hypothesis that there was an association between tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) release and measured coronary collateral flow in patients undergoing primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI). BACKGROUND: Tumour necrosis factor-alpha and IL-6 increase during acute myocardial infarction (AMI). However, their relation to coronary collateral flow is unknown. METHODS: Twelve patients with AMI due to complete thrombotic coronary occlusion underwent primary PCI within 12 h of symptom onset. Doppler-derived collateral flow index (CFI) was measured during first balloon inflation. TNF-alpha, IL-6, creatine kinase (CK), CK-MB fraction were measured from venous plasma samples serially for 24 h. Area at risk was determined off-line by coronary arteriography. Ejection fraction (EF) was measured using biplane left ventricular angiography. RESULTS: Maximal CK release varied between 569 and 6276 U/l and area at risk varied between 7 and 47% of myocardium. Tumour necrosis factor-alpha (peak 4.4+/-0.5 pg/ml) and IL-6 (peak 35.5+/-3.0 pg/ml) increased in all patients. Peak TNF-alpha and IL-6 release was independent of CK, CKMB. No minimal threshold of myocardial necrosis for cytokine expression could be detected. Similarly, TNF-alpha and IL-6 release was also independent of time to reperfusion, area at risk or EF. Using univariate regression analysis, peak TNF-alpha inversely correlated with CFI (r = 0.67, P = 0.017) whereas IL-6 positively correlated with CFI (r = 0.76, P = 0.004). CONCLUSIONS: Acute myocardial infarction is associated with a significant rise in TNF-alpha and IL-6 levels independent of infarct size or myonecrosis. Tumour necrosis factor-alpha and IL-6 correlate dichotomously with CFI indicating differing roles in reperfused AMI.

Aged↗
PubMed2005

Endovascular treatment of an internal iliac artery aneurysm using a nitinol vascular occlusion plug.

PURPOSE: To report endovascular occlusion of an internal iliac artery (IIA) aneurysm with an Amplatz nitinol vascular occlusion plug. CASE REPORT: A 71-year-old asymptomatic man who had previously undergone open aortic aneurysm repair presented for annual follow-up. A bifurcated Dacron graft had been inserted 12 years ago from the infrarenal aorta to the left common femoral artery and the right common iliac artery. The left common iliac artery was ligated proximally, and the left external iliac artery (EIA) provided retrograde flow into the IIA. Magnetic resonance imaging (MRI) revealed a 7.4-cm aneurysm of the left IIA. After transfemoral calibrated catheter angiography was performed, the proximal EIA was occluded with an Amplatz nitinol vascular occlusion plug. In addition, microcoils were placed distal to the vascular plug to achieve complete thrombosis of the vessel. One day after treatment, the patient was discharged free of symptoms after MRI had shown complete obliteration of the IIA aneurysm. At 6 months, the patient was free from symptoms, and angiography confirmed exclusion of the IIA aneurysm. CONCLUSIONS: This case illustrates the technical feasibility and successful short-term follow-up of a novel embolization approach to IIA aneurysms in patients with an aortofemoral graft.

Aged↗