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Biomedical subjects

D Hausmann

Publications and source records attributed to D Hausmann.

At least 19 recordsLinked to original sources
PubMed2004

Incidence and time course of intimal plaque formation in the right coronary artery after radiofrequency current application detected by intracoronary ultrasound.

BACKGROUND: Despite the current clinical use of radiofrequency (RF) catheter ablation in infants and children, the late effects of RF current application at immature myocardium remain unclear. The purpose of this study was to investigate incidence and time course of coronary lesions after RF current application at developing myocardium in an animal model. RESULTS: In 10 pigs, 6 weeks of age (13+/-2 kg), RF current (500 kHz) was delivered by temperature guidance (75 degrees C) using a steerable electrode catheter (4 mm tip electrode) over 30-second periods. RF lesions were created at the lateral right atrial wall at the tricuspid valve annulus and the lateral left atrial and ventricular wall at the mitral valve annulus. Subsequent coronary angiography and intracoronary ultrasound (ICUS) of the right coronary artery (RCA) and the left circumflex artery (CX) were performed 3, 6, 9 and 12 months after RF current application. Quantitative coronary angiography did not exhibit any significant stenosis of the vessels during the study period. Intimal lesions of the RCA were documented for the first time at the 6-month study in 3 animals by ICUS (mean plaque area 2.2+/-0.2 mm(2), mean area stenosis 30.4+/-4.0%). There was no significant change in lesion length, area stenosis and plaque area at the 9- and 12-month studies. All 3 coronary artery lesions were confirmed in close proximity to myocardial RF lesions by histological examination 12 months after RF delivery. No intimal plaque formation of the CX was observed. CONCLUSIONS: Affection of the RCA as a late sequel after RF current application at the lateral right atrial wall occurred in 3 out of 8 long-term surviving pigs. Three to six months seem to be the time frame for the development of intimal lesions after RF delivery. In this experimental setting, angiography failed to detect these intimal changes. The potential risk of coronary affection may be important for catheter ablation procedures at the right atrial myocardium in infants and small children.

Animals↗
PubMed2002

Endothelial function in patients with peripheral vascular disease: influence of prostaglandin E1.

Peripheral arterial occlusive disease (PAOD) is characterized by atherosclerotic lesions in large vessels and disturbances on the microcirculatory level. In the local regulation of vascular tone and microvascular perfusion, vascular endothelium plays a key role. For many years prostaglandin E1 (PGE1) has been used for the treatment of PAOD. Because PGE1 has only moderate effects on blood flow other mechanisms may be relevant for the therapeutical efficacy. The aim of our pilot study was to evaluate endothelial function in patients with PAOD and to investigate the impact of PGE1 on endothelial-dependent vasodilation in peripheral vesselsIn 8 controls and in 8 patients with PAOD stage II, endothelial-dependent vascular responses of the femoral vessels to increasing doses of acetylcholine (30,60,90 microg/min) were determined by Doppler flow velocity measurements in the common femoral artery. Furthermore, vascular reactivity was evaluated before and immediately after intravenous infusion of 30 microg PGE1/30 min in patients. Endothelial-dependent vasodilation was significantly reduced in patients with PAOD compared to control subjects. Infusion of PGE1 neither increased blood flow in the common femoral artery nor endothelium-dependent vasodilation of peripheral resistance vessels as indicated by unchanged reaction to acetylcholine. In conclusion, endothelial function is impaired in patients with PAOD. Administration of PGE1 did not increase femoral artery blood flow or improve endothelial-dependent reactivity of peripheral resistance vessels in patients with PAOD. Therefore, beneficial effects of PGE1 in peripheral vascular disease cannot be attributed to an increase in blood supply or an improvement of endothelial-dependent vasodilation.

Aged↗
PubMed2001

Use of intravascular ultrasound to compare effects of different strategies of lipid-lowering therapy on plaque volume and composition in patients with coronary artery disease.

BACKGROUND: We studied whether lipid-lowering therapy with atorvastatin (target LDL cholesterol [LDL-C] <100 mg/dL) compared with a moderate treatment regimen that used other lipid-lowering drugs led to a lesser progression of atherosclerosis and to different changes in plaque echogenicity in patients with coronary artery disease. METHODS AND RESULTS: This study was a 12-month, open-label, randomized, multicenter trial, which used serial 3D intracoronary ultrasound to calculate plaque volume and plaque echogenicity. After transcatheter therapy, 131 patients were randomized (atorvastatin n=65, usual care n=66). The target plaque had to be a minor lesion (ie, a diameter stenosis of <50% on angiography). After 12 months, mean LDL-C was reduced from 155 to 86 mg/dL in the atorvastatin group and from 166 to 140 mg/dL in the usual care group. Mean absolute plaque volume showed a larger increase in the usual care group compared with the atorvastatin group (usual care 9.6+/-28.1 mm(3), atorvastatin 1.2+/-30.4 mm(3); P=0.191). The hyperechogenicity index of the plaque increased to a larger extent for the atorvastatin group than for the usual care group, with a significant treatment effect for the percent change (atorvastatin 42.2%, usual care 10.1%; P=0.021). CONCLUSIONS: One year of lipid-lowering therapy to <100 mg/dL LDL-C most likely led to a slowdown of plaque growth of minor lesions. The significantly larger increase in plaque hyperechogenicity is most likely due to a change in plaque composition.

Anticholesteremic Agents↗
PubMed2000

[Intracoronary ultrasound].

IVUS imaging provides a 2-dimensional, cross-sectional view into the lumen and vessel wall structure of coronary arteries; it is superior to angiography with regard to visualization about several aspects of coronary artery disease. IVUS has given important information on the development and progression of coronary atherosclerosis. Moreover, IVUS has improved our understanding of the mechanisms of percutaneous interventions and restenosis. IVUS-guided balloon sizing during PTCA may increase acute lumen gain as compared to conventional angiographic guidance. Optimization of stent implantation by IVUS guidance also results in larger initial lumen gain than with angiographic control; this approach, however, does not reduce restenosis rates. In summary, IVUS is an optional imaging modality that provides clinically useful information in selected patients.

Angioplasty, Balloon, Coronary↗
PubMed1999

Intravascular ultrasound and stent implantation: intraobserver and interobserver variability.

BACKGROUND: Intravascular ultrasound (IVUS) imaging can be used to optimize implantation of intracoronary stents; the variability of the measurements, however, remains unclear. Our aim in this study was to determine the intraobserver and interobserver variability of IVUS measurements after stent implantation. METHODS: Ninety-four patients underwent implantation of 100 Palmaz-Schatz stents in 98 lesions (79 de novo and 19 restenotic). IVUS measurements (3.5F, 30 MHz) of proximal and distal reference sections and of the smallest stent lumen were performed by 2 investigators. RESULTS: Intraobserver and interobserver correlations, respectively, were r = 0.96 and 0.93 for the proximal reference, r = 0.94 and 0.92 for the distal reference, and r = 0.97 and 0.97 for minimal stent lumen. Stent expansion (minimal lumen in the stent/mean reference area) showed a variability of r = 0.80 and 0.70. Taking a cutoff point of 90% for adequacy of stent expansion, observers agreed in only 77% whether the stent was adequately or inadequately expanded. CONCLUSIONS: IVUS enables reproducible lumen measurements in stents and reference sections. The degree of stent expansion, however, underlies a high measurement variability that can lead to different therapeutic strategies.

Coronary Disease↗
PubMed1999

Incomplete expansion of Palmaz-Schatz stents despite high-pressure implantation technique: impact on target lesion revascularization.

Improved expansion of stents using high-pressure implantation technique with subsequent antiplatelet therapy has improved patient outcome regarding the incidence of subacute stent thrombosis, bleeding complications and restenosis. Whether high-pressure implantation per se guarantees adequate stent expansion remains unclear. The aim of the study was to determine (1) stent expansion after high-pressure implantation technique and (2) whether stent expansion influences rate of target lesion revascularization within 6 months of follow-up. One hundred Palmaz-Schatz stents were implanted in 98 lesions (91 native vessels, 7 graft vessels) of 94 patients using high-pressure implantation technique (balloon pressure 12-20 atm). Stent expansion was investigated using intravascular ultrasound imaging (IVUS). Clinical follow-up of the patients was performed for 6 months. After implantation, stent/mean reference ratio was 0.81 +/- 0.16. Noncompliant balloons used for implantation were chosen by angiographic criteria. Mean balloon/reference ratio was 1.08 +/- 0.22; therefore balloons were not undersized. Additional balloon dilataion using higher pressures and/or larger balloons based on IVUS criteria and subsequent IVUS measurements was performed in 52 patients (55%); in these patients, stent expansion improved from 79 +/- 16 to 91 +/- 15% (mean +/- SD) of average reference areas (p < 0.002). Within the 6 months' clinical follow-up, target lesion revascularization was performed in 19 patients (20%). The only prognostic factors for the development of in-stent restenosis requiring target lesion revascularization were the vessel size (p < 0.05) and the extent of plaque distal to the stents (p < 0.05). Implantation of Palmaz-Schatz stents using high-pressure technique does not guarantee adequate stent expansion. Additional dilatation with higher pressures and/or larger balloons improves stent expansion. The size of the stented vessel and the extent of plaque at the distal stent end (residual outflow stenosis) but not the degree of stent expansion were predictors for target lesion revascularization within 6 months' follow-up.

Adult↗
PubMed1998

How to standardize vasomotor tone in serial studies based on quantitation of coronary dimensions?

In patients with coronary artery disease including those after coronary bypass graft operation and heart transplantation intervention studies based on serial quantitative coronary angiography, in part combined with intravascular ultrasound, are of increasing relevance. Since vasomotor tone of epicardial coronary arteries is influenced by a variety of factors, angiographic follow-up studies require standardization of coronary tone by induction of maximal dilation. We reviewed the effects of the most potent coronary vasodilatory drug groups, calcium antagonists and nitrocompounds, on coronary diameters. Intravenous or intracoronary injections of verapamil, diltiazem, nifedipine, nicardipine, and nisoldipine can cause profound coronary dilation which has been shown to be maximal with verapamil and nisoldipine. Shortcomings of calcium antagonists include short or unknown duration of action after bolus administration, severe drop in blood pressure, and lack of commercial availability of solutions for injection of many substances. Isosorbide dinitrate induces profound coronary dilation; however, after sublingual administration marked blood pressure decrease can occur, and the duration of action and ideal dose of intracoronary isosorbide dinitrate has not been investigated yet. Injections of molsidomine and its active metabolite, SIN-1, cause longlasting, reproducible, maximal coronary dilation, although only after a waiting period of at least 10 minutes; unfortunately, SIN-1 is only commercially available in France. Nitroglycerin induces reproducible maximal coronary dilation and is easy to administer sublingually or as intracoronary bolus injection with rapid onset of action and no major side effects. The short duration of action may require repeated administrations. To date, repeated intracoronary bolus injections of 0.1 mg nitroglycerin every 10 minutes seem to be the optimal known regimen for standardization of coronary vasomotor tone in serial angiographic studies. Further investigations in this field with old and new vasodilatory drugs are recommendable.

Calcium Channel Blockers↗
PubMed1998

Intravascular ultrasound-guided optimized stent deployment. Immediate and 6 months clinical and angiographic results from the Multicenter Ultrasound Stenting in Coronaries Study (MUSIC Study)

OBJECTIVES: A study was set up to validate the safety and feasibility of intravascular ultrasound-guided stenting without subsequent anticoagulation, and its impact on the 6 months restenosis rate. METHODS: The study was designed to be multicentred, prospective, and observational. RESULTS: One hundred and sixty-one patients with stable angina and a de novo coronary artery lesion were enrolled. In four patients, the implantation of a Palmaz-Schatz (with spiral bridge) stent had failed. One of these four patients died 3 days following bypass surgery. In two other patients, intravascular ultrasound assessment was not performed. One hundred and twenty-five of the remaining 155 patients (81%) were treated with aspirin (100 mg x day(-1)), because all three criteria for optimized stent expansion were met. Twenty-two of the remaining 38 patients (25%), in whom at least one criterion was not met were treated with aspirin and acenocoumarol (3 months, INR 2.5-3.5), while 16 patients only received aspirin. Stent thrombosis was documented in two patients (1.3%) for which repeat angioplasty was performed. During the hospital stay, there were no deaths or Q-wave myocardial infarctions. Five patients (3.2%) sustained a non-Q-wave myocardial infarction. During the follow-up period (198+/-38 days, complete for all patients, except one), one patient (0.6%) sustained a Q-wave myocardial infarction, one (0.6%) underwent bypass surgery, and repeat angioplasty was performed in nine patients (5.7%). In two of the nine patients, repeat angioplasty involved another lesion. Therefore, the target lesion revascularization rate during follow-up was 4.5% (seven patients). At quantitative coronary angiography, the minimal lumen diameter (mean+/-SD) increased from 1.12+/-0.34 mm before to 2.89+/-0.35 mm after stenting. Repeat angiography at 6 months was performed in 144 patients (92%). The minimal lumen diameter at follow-up was 2.12+/-0.67 mm. Restenosis (diameter stenosis of 50% or more) was documented in 12 patients or 8.3%. When the two patients with documented stent thrombosis are included, the restenosis rate amounts to 97%. CONCLUSIONS: These data confirm that, in selected patients, stents can safely be implanted without the use of systemic anticoagulation, provided optimal stent expansion is achieved. The exact role of intravascular ultrasound in the achievement of these results needs to be established by appropriately designed studies. In the meantime, intravascular ultrasound coupled with the Palmaz-Schatz stent incorporating a spiral bridge, may have contributed considerably to the immediate angiographic outcome, which in turn may explain the favourable clinical and angiographic outcome at 6 months.

Aged↗
PubMed1998

Impact of the Location of Recurrent Stenosis on Revascularization after Coronary Palmaz-Schatz Stent Implantation.

In 69 patients the incidence of target lesion revascularization during 3-year follow-up after single Palmaz-Schatz stent implantation was compared with the in-stent location of recurrent stenoses at 6-month follow-up angiography. A stenosis was defined as a lesion with > 15% diameter stenosis. After stent implantation, 17 mid-type, 10 proximal and 5 distal-type residual stenoses were found. At follow-up, 56 mid-type, 11 proximal and 6 distal-type stenoses were measured. Only proximal-type residual stenoses revealed an increase in diameter stenosis (40 +/- 15% vs 27 +/- 6%; p < 0.05). Five out of 11 patients (45%) with proximal-type recurrent stenoses underwent revascularization during follow-up versus 8 out of 56 (14%) with mid-type and none of the 6 patients with distal-type stenoses (p = not significant). This clear trend Ñ toward more progression and target lesion revascularization procedures in proximal-type recurrent stenoses mainly developing from residual stenoses left after stent implantation Ñ should be verified in larger patient collectives.

Journal Article↗
PubMed1997

Intravascular ultrasound-guided percutaneous fenestration of the intimal flap in the dissected aorta.

BACKGROUND: Aortic dissection with branch obstruction is associated with high morbidity and mortality. Fenestration of the dissection flap to relieve distal vessel ischemia is at present largely performed surgically. The surgical mortality and morbidity are high, because most patients are poor candidates for anesthesia or surgery. METHODS AND RESULTS: Nine percutaneous fenestrations (one with additional stenting of the infrarenal true aortic lumen) were performed under local anesthesia in seven patients with aortic dissection. The presenting symptoms were abdominal angina or claudication. By the transfemoral approach, the intimal flap was initially punctured with a needle-catheter combination through which a guidewire was placed across the dissection flap. The fenestration was carried out with a balloon catheter introduced over the guidewire. The procedure was performed under on-line guidance with intravascular ultrasound imaging. The procedure was performed successfully and without complications in all patients. After intervention, symptoms resolved in all seven patients. CONCLUSIONS: Intravascular ultrasound-guided percutaneous fenestration of the intimal flap in symptomatic aortic dissections with distal vessel involvement is a technically feasible and safe procedure that can effectively relieve the patient's symptoms.

Adult↗
PubMed1997

Angiographically undetected plaque in the left main coronary artery. Findings of intravascular ultrasound imaging.

The absence of angiographic findings despite significant coronary artery disease has been previously described. Possible explanations for the limitation of plaque detection by angiography include compensatory vessel enlargement in face of intracoronary plaque formation, the lack of reference segments in diffuse atherosclerosis as well as technical limitations. Intracoronary ultrasound (ICUS) imaging provides the possibility of direct plaque visualization. We studied angiographically normal left main coronary arteries (LMCA) in 72 patients prior to diagnostic angiography or therapeutic interventions using ICUS (30 MHz). ICUS images were continuously recorded and recalled from memory for morphometric analysis. Lumen area, plaque area and the total vessel area were determined by computer software. ICUS imaging revealed atherosclerotic plaque in 55 of the 72 patients with angiographically normal LMCA (76%). The average plaque area stenosis was 22 +/- 12% (range 3-44%). Total vessel area showed a significant direct correlation with plaque area, indicating compensation of coronary plaque formation. The average percent change in plaque area (difference between maximal and minimal plaque area within the LMCA) was 11 +/- 19%, indicating a diffuse pattern. Measurement of change in lumen area (difference between maximal and minimal lumen area within the LMCA) revealed an average value of 6 +/- 7%. Lumen area of the LMCA was 15.9 +/- 3.2 mm2 in patients with and 17.2 +/- 1.9 mm2 without atherosclerotic plaque (n.s.). Thus, the lack of angiographic changes despite advanced plaque formation in the LMCA could be explained by compensatory vessel enlargement and by diffuse distribution of plaque in the vessel; true lumen narrowings overlooked by angiography seem not to account for the failure of angiography to detect plaque.

Aged↗
PubMed1997

Acute effects of celiprolol on angiographically normal and stenotic coronary arteries.

Unselective and beta 1-selective beta-blockers may induce vasoconstriction of normal and stenotic epicardial coronary arteries. To analyze the influence of the "vasodilatory" beta-blocker celiprolol on coronary vasomotility, 0.4 mg celiprolol/kg were intravenously infused over 4 minutes in 13 patients with coronary artery disease. Coronary angiograms were taken before (control) and at 4, 6, 8, 10, 15, and 20 minutes after the onset of infusion and 4 minutes after final sublingual administration of 0.4 mg nitroglycerin. Quantitative analysis of cinefilms demonstrated no significant diameter changes in angiographically normal coronary segments and stenoses. The vasodilatory capacity of normal segments (18 +/- 12%; p < 0.001) and stenoses (17 +/- 14%; p < 0.01) was proven by nitroglycerin. Systolic blood pressure, heart rate, and pulmonary wedge pressure revealed no significant changes with celiprolol. Thus, celiprolol exerts no vasoconstricting effects on angiographically normal and stenotic coronary arteries.

Adrenergic beta-Antagonists↗
PubMed1997

Comparative in-vitro validation of eight first- and second-generation quantitative coronary angiography systems.

BACKGROUND: It is known that first-generation quantitative coronary angiography (QCA) systems overestimate small vessel sizes owing to the point-spread function of the respective X-ray imaging chain. With second-generation systems new algorithms were introduced to correct for this source of error. OBJECTIVE: To evaluate the efficiency of the modified contour detection algorithms. METHODS: Six second-generation QCA systems (CMS, QANSAD, AWOS, CAAS II, Cardio 500, and Angioimage) were validated and compared with first-generation systems (CAAS and ARTREK). By using an arterial phantom consisting of stenotic and nonstenotic glass tubes (of diameters 0.5-5.0 mm) the accuracy and precision of each analysis system, as well as their additional accuracy and precision values for phantom diameters < or = 1.0 mm were determined. RESULTS: All systems had high accuracy and precision values, but first-generation systems overestimated small vessel diameters. With second-generation systems a significantly improved accuracy in the submillimeter range (an accuracy within +/-0.028 mm) was obtained. This improvement was accompanied by a moderate reduction in precision in the submillimeter range. CONCLUSION: The new algorithms of the second-generation QCA systems allow accurate and reliable measurements of small coronary dimensions and, therefore, precise analysis of coronary stenoses of moderate-to-high grade seems feasible with the improved accuracy of the new systems.

Algorithms↗