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Biomedical subjects

M Haude

Publications and source records attributed to M Haude.

At least 109 records · Page 6Linked to original sources
PubMed1996

[Effect of high insufflation pressures on elastic recoil forces and vascular resistance after balloon dilatation].

In this study, we examined whether percutaneous coronary angioplasty (PTCA) of native coronary arteries with high inflation pressure can improve the immediate postinterventional result in comparison to PTCA with nominal inflation pressure. Using quantitative coronary angiography, we analyzed the coronary angiograms of 24 patients who underwent PTCA with nominal inflation pressure (< 10 atm; group 1) and of 20 patients who underwent PTCA with high inflation pressure (> or = 10 atm; group 2). Only balloon catheters with little compliance were used. The following variables were recorded: 1) minimal luminal diameter (MLD), reference diameter and percent diameter stenosis before and after PTCA, 2) average balloon diameter during PTCA, 3) balloon/artery diameter ratio, 4) acute luminal gain (difference between MLD before and after PTCA), 5) nominal elastic recoil (difference between nominal balloon diameter and MLD after PTCA), 6) actual elastic recoil (difference between average balloon diameter during PTCA and MLD after PTCA). Nominal balloon diameter, reference diameter before and after PTCA and the balloon/artery diameter ratio were similar in both groups. Application of high inflation pressure resulted in a greater average balloon diameter. In group 2 (high inflation pressure), average balloon diameter amounted to 94 +/- 12% of nominal balloon diameter, whereas in group 1 (nominal inflation pressure), it reached only 84 +/- 9% of nominal balloon diameter. Actual elastic recoil was not different between the two groups. Nominal elastic recoil, however, was greater in the cohort which received PTCA with nominal inflation pressure (1.13 +/- 0.35 mm vs. 0.83 +/- 0.28 mm; p < 0.02). After use of high inflation pressure, acute postinterventional luminal gain was significantly increased (1.04 +/- 0.25 mm vs. 0.77 +/- 0.34 mm; p < 0.02) and the postinterventional percent diameter stenosis was significantly lower (12 +/- 10% vs. 24 +/- 13%; p < 0.05). Application of high inflation pressure improves the postinterventional result after PTCA because of a greater acute luminal gain. The stenotic coronary artery is expanded to a greater degree, and actual elastic recoil remains unchanged.

Adult↗
PubMed1996

[High frequency rotational angioplasty].

High-speed rotational coronary atherectomy is an alternative method to treat complex, especially calcified coronary stenoses. A rotating burr tip removes the occlusive plaque tissue. The applied rotating frequency is between 160 000 to 190 000 rpm. The primary technical success-rate for high frequency rotational atherectomy alone yields between 50 to 60% on average. Associated with consecutive additional balloon angioplasty, the success rate is between 80 and 95% when treating complex type B II or C stenoses. Today, the usage of a single burr tip size with adjunctive balloon angioplasty has become a standard procedure. The occurrence of serious complications such as extensive dissections or thrombotic vessel occlusion is a rare phenomenon after high-speed rotational atherectomy compared to coronary balloon angioplasty, whereas coronary spasm is more common after high-speed rotational atherectomy. According to the actual results, high-speed rotational angioplasty did not lower the rate of long-term restenosis, compared to the results achieved by balloon angioplasty alone. The rate of long-term restenosis is reported to be between 40 to 50% after highspeed rotational angioplasty with or without adjunctive balloon angioplasty.

Atherectomy, Coronary↗
PubMed1996

[The significance of intravascular ultrasound in differential diagnosis and therapy of coronary stenoses].

Intravascular ultrasound (IVUS) has emerged from being a research tool to becoming an important aspect in invasive cardiology, because it offers the possibility to obtain "in vivo" histology, including the vessel wall, while angiography allows for lumenograms only. The reasons for performing IVUS can be divided into either diagnostic or intervention associated indications. Diagnostic strength of IVUS is the ability to monitor compensatory coronary artery enlargement as a response to arteriosclerosis, to reveal occult left main stem disease, and angiographically "silent" arteriosclerosis. The peri-interventional potentials of IVUS are the ability to allow optimal device selection, i.e., rotablators in calcified lesions or atherectomy devices in large plaque burden. The effects of PTCA on vessel wall morphology can be studied in great detail and the effect on true luminal gain assessed almost on-line. Several groups showed that the residual plaque area after angiographically successful PTCA lies in the range of 60%. A significant reduction of this number may influence long-term outcome after PTCA. Minimal luminal areas after PTCA seem to be an indicator of restenosis, while the morphological appearance alone seems to be less predictive. Intravascular monitoring of stent implantation led to high-pressure stent deployment with significant increase in postprocedural luminal diameters and, finally, the ability to withold anticoagulation in patients with optimal stent deployment. Furthermore, integrated devices, like balloons on IVUS catheters, steerable catheters, integrated flow measurements and pressure transducers will further increase the usefulness of IVUS.

Angioplasty, Balloon, Coronary↗
PubMed1995

Acute coronary artery closure following intracoronary ultrasound examination.

Two patients undergoing intracoronary ultrasound examination were complicated by acute coronary artery closure. One of the complications was thought to be caused by intimal dissection and thrombus formation and the other was thought to be caused by intimal dissection and subsequent embolization. The complications were successfully managed conservatively in both cases.

Acute Disease↗
PubMed1995

Improvement of coronary morphology and blood flow after stenting. Assessment by intravascular ultrasound and intracoronary Doppler.

Intravascular ultrasound (IVUS) and intracoronary Doppler (ICD) were performed in eight patients (54.3 +/- 6.5 years, 6 male) immediately after PTCA and after stenting. ICD was also performed before PTCA. After PTCA, IVUS has demonstrated intimal rupture in all patients. After stenting, IVUS revealed wall wrapping of the intimal flap with a free lumen in all patients. The lumen diameter was 2.42 +/- 0.55 mm after PTCA and was 2.74 +/- 0.49 mm after stenting (p < 0.001). The cross-sectional area increased from 4.70 +/- 1.99 mm2 post-PTCA to 6.40 +/- 2.15 mm2 post-stent (p < 0.005). Coronary flow velocity reserve, calculated by the ratio of mean flow velocity at rest and after intracoronary papaverine administration, increased from 2.05 +/- 1.01 to 2.99 +/- 1.14 after PTCA (p = 0.015); and increased to 4.51 +/- 1.33 after stenting (p < 0.001). The morphological data derived from IVUS correlated with the functional information obtained with ICD. In addition to its established role in bail out situations, stent implantation may be considered when a suboptimal morphological and functional result has been demonstrated.

Angioplasty, Balloon, Coronary↗
PubMed1995

Improving the applicability of myocardial densitometry and parametric imaging by extended automated densogram analysis.

In clinical applications the analysis of X-ray contrast densograms acquired in regions of interest (ROI's) over the myocardium is disturbed by many complex factors. For this reason we acquire redundant densogram information for quality control before extracting densitometric parameters. In our approach, initially some stable measures of quality for densograms are used to lower the influence of poor quality densograms by a quality weighted averaging. For example a shape quality measure, Q1, is calculated using regions of optimal and minimal acceptable quality defined with respect to a prototype densogram. Not a few myocardial ROI's yield densograms that differ from single-source densograms (SSD's) due to e.g. superposition of different perfusion beds or the position of the ROI relative to the coronary sinus or stenoses. This might result in a densogram shape with oscillating or plateau behavior. For densograms of a such general shape many parameters defined in the usual way do not depend smoothly on the densogram values. The conventional definitions of some parameters (appearance time, rise time) are therefore extended for application to multi-maxima densograms as well as to SSD's. These new methods are evaluated using digitized clinical angiocardiograms and are applied to parametric imaging (pixeldensograms) in a slightly modified way. Taking into account the densogram quality, its shape and its origin results in a considerable improvement both for densitometry and parametric imaging of myocardial perfusion.

Absorptiometry, Photon↗
PubMed1995

Intravascular ultrasound approach to the diagnosis of coronary artery aneurysms.

Coronary artery aneurysms are usually diagnosed by contrast coronary angiography, which portrays the silhouette of the lumen but cannot distinguish true and false aneurysms. To differentiate true and false aneurysms and to study the morphologic changes of the vessel wall, intravascular ultrasound (IVUS) was performed in patients with angiographic signs of coronary artery aneurysms. We used a 4.8F or 3.5F, 20 MHz IVUS catheter for ultrasound examination. Fourteen patients (12 men and two women ranging in age from 43 to 73 years) with angiographic signs of coronary aneurysm were enrolled. IVUS imaging was optimally obtained in all patients. The vessel area, lumen area, and plaque area of the aneurysm segment and of the proximal and distal segments were determined. IVUS showed that both the proximal and distal reference segments were severely affected by atherosclerotic lesions in all the patients and by calcium deposits in six patients. The percent stenoses were 63.0% +/- 13.7% and 60.9% +/- 17.8% in the proximal and distal reference segments, respectively. In nine patients the walls of the aneurysms showed signs of atherosclerosis. Three angiographically indicated aneurysms were found to be plaque ruptures. Although the lumen and the vessel areas of the aneurysm segments were larger than those of the proximal and distal segments (p < 0.01 and (p < 0.001), no significant differences in plaque area and plaque composition were found between the aneurysm segment and adjacent vessel segments (p > 0.05). In conclusion, IVUS allows detailed characterization of coronary aneurysms. Atherosclerosis seems to play an important role in the formation of acquired coronary aneurysms.

Adult↗
PubMed1995

Guidance of anticoagulation after intracoronary implantation of Palmaz-Schatz stents by monitoring prothrombin and prothrombin fragment 1 + 2.

The primary objective of this study was to apply a sophisticated coagulation monitoring system including estimation of the concentration of prothrombin fragment 1 + 2 (PTF 1 + 2) and the activity of prothrombin (coagulation factor II or FII) to cases of stent implantation and to compare the results with those of standard coagulation tests. The secondary objective was to detect the incidence after stenting of subacute thrombosis (SAT) and bleeding complications in these patients and to compare the results with those of a group of patients with stent implantation in whom coagulation was monitored exclusively by standard tests. SAT several days after coronary stenting occurs in up to 20% despite aggressive intravenous and overlapping oral anticoagulation. According to a prospective study protocol 120 consecutive patients with implantation of 155 Palmaz-Schatz stents underwent coagulation monitoring including single daily estimation of the concentration of PTF1 + 2 (target range < 0.5 nmol/L) and of FII activity (15% to 35%) in addition to the standard tests of thrombin time (TT), partial thromboplastin time (aPTT), international normalized ratio (INR), antithrombin III (ATIII), and fibrinogen. Adjustment of heparin and phenprocoumon dosages in this study group was based only on the results of PTF1 + 2 and FII measurements. A control group consisted of 53 patients with implantation of 64 stents who were matched for baseline, angiographic, and procedure-related characteristics. After stenting, anticoagulation was monitored by estimation of TT (target range > 70 seconds), aPTT (> 70 seconds), INR (3.0 to 4.5), AT III (> 80%), and fibrinogen (< 450 mg/dl) in this control group. There was a weak correlation between PTF1 + 2 and aPTT (r = 0.337; PTF1 + 2 = -0.00169aPTT + 0.491) and PTF1 + 2 and TT (r = 0.328; PTF1 + 2 = -0.00142TT + 0.494). A better correlation was found between FII and INR (r = 0.983; FII = -23.8 INR + 134). Stable oral anticoagulation was maintained 2.8 +/- 0.9 days later according to an FII concentration of < 35% compared with an INR > 3. The incidence of SAT was 3.3% with 3.0% for elective versus 3.8% for nonelective stenting. The sensitivity, specificity, and accuracy of the PTF1 + 2 test were 100%, 88%, and 88%, respectively. In the control group the incidence of SAT was 17%, with 16.1% for elective versus 18% for nonelective stenting. Major bleeding complications occurred in 10% (study group) and in 11.3% (control group) of patients (no statistical difference).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1995

Intravascular ultrasound after low and high inflation pressure coronary artery stent implantation.

OBJECTIVES: We sought to characterize the differences seen after low or high pressure coronary artery stent deployment as assessed by intravascular ultrasound. BACKGROUND: Until 1992, the success of stent deployment was assessed by angiographic criteria only, but in 1993 the procedure was expanded to include postprocedural single-use intravascular ultrasound imaging. Ultrasound criteria for successful stent deployment were 1) symmetry, 2) minimal lumen diameter > 3.0 mm, 3) no echo-free spaces between the stent and the vessel, and 4) no uncovered dissections. METHODS: We used mechanical 4.8F or 3.5F 20- or 30-MHz monorail single-use intravascular ultrasound catheters. RESULTS: Fifty-two patients were included, 28 treated in 1991 and 1992 (group A) and 24 treated in 1993 or 1994 (group B); 87% of patients underwent elective stent implantation. The number of echocardiographic studies per patient increased from 1 +/- 0.1 (mean +/- SD) in group A to 2.0 +/- 0.85 in group B. Mean maximal balloon size increased from 3.3 +/- 0.33 to 3.73 +/- 0.24 mm and maximal inflation pressure from 6.9 +/- 1.1 to 15.8 +/- 2.4 bar (p < 0.001). The eccentricity index was 0.915 +/- 0.04 in group B versus 0.87 +/- 0.05 in group A. Minimal lumen diameter measured by echocardiography increased from 2.55 +/- 0.41 mm in group A to 3.14 +/- 0.37 mm in group B. The final mean values per cross-sectional area as a percent of calculated balloon area were similar in group A (67.5 +/- 23%) and group B (66.5 +/- 22.9%). No major acute complications occurred in either group; subacute thrombosis developed in two patients, both in group A. CONCLUSIONS: Intravascular ultrasound data confirm that high pressure stent deployment leads to increased minimal lumen area. Despite high pressure stent deployment, homogeneous stent geometry and optimal stent expansion were not observed in all patients.

Aged↗
PubMed1995

Regression of pre-existing coronary artery disease in a donor heart after cardiac transplantation.

This report is about the angiographic follow-up, over 5 years, in a patient with urgent heart transplantation grafted with an atherosclerotic donor heart because of severe congestive heart failure due to dilative cardiomyopathy. Sequential quantitative angiography documented a regression of the luminal narrowing of a focal lesion in the right coronary artery with a minimal luminal diameter of 1.38 mm (56% diameter stenosis) in 1988 to 2.78 mm (13%) in 1993. During this catheterization in 1993 intravascular ultrasound imaging illustrated almost no atherosclerotic vessel wall abnormalities at the site of the previous angiographic luminal narrowing as well as in the adjacent segments. These findings might promote the potential acceptance of heart transplant donors with a certain extent of coronary artery disease in the case of urgent organ request, if close follow-up and strict guidance of the patient by the transplanting team is feasible.

Adolescent↗
PubMed1995

Intravascular ultrasound: a guide for management of complications during intervention?

Within a few years, intravascular ultrasound (IVUS) has emerged from a research tool into an intrinsic part of modern invasive cardiology, mainly because histology can be obtained 'in-vivo'. For the first time in invasive cardiology it is possible to base decisions not only on lumenograms but also on vessel wall assessment. IVUS can be used as both a diagnostic tool and for intervention purposes. Its diagnostic strength lies in its ability to monitor compensatory coronary artery enlargement as a response to arteriosclerosis, to reveal occult left main stem disease, and angiographically 'silent' arteriosclerosis. As regards intervention, IVUS aids in optimal device selection, i.e. whether to use rotablators in calcified lesions or atherectomy devices in large plaques. The effects of PTCA on vessel wall morphology can be studied in great detail and the effect on luminal gain assessed almost on-line. Several groups have shown that the residual plaque area, even after angiographically successful PTCA, is about 60%. A significant reduction in this percentage may influence long-term outcome after PTCA. Luminal areas that are minimal after PTCA seem to indicate restenosis, while morphological appearance on its own seems to be less predictive. One answer to the shortcomings of standard PTCA are coronary artery stents. Intravascular monitoring of stent expansion led to the deployment of high-pressure stents with a significant increase in post-procedural luminal diameters, and finally the ability to withhold anticoagulation in patients with optimal stent deployment. Furthermore, integrated devices, such as balloons on IVUS catheters, steerable catheters, integrated flow measurements, pressure transducers, and, hopefully, tissue characterization, will further enhance the usefulness of IVUS.

Angioplasty, Balloon, Coronary↗
PubMed1995

Silent healing of spontaneous plaque disruption demonstrated by intracoronary ultrasound.

Intracoronary ultrasound was performed at diagnostic coronary angiography and 10 days later in a 45-year-old patient with a 3-day history of acute inferior myocardial infarction. Coronary angiography showed considerable stenosis (80%) in the distal right coronary artery (RCA) (pre the crux) and what appeared to be a dissection in the middle RCA. Intracoronary ultrasound identified this as plaque disruption. Coronary balloon angioplasty was then performed in the distal stenotic segment. Follow-up angiography 10 days after coronary intervention revealed that the flap in the lumen had disappeared. Intracoronary ultrasound imaging showed that the ruptured plaque had resealed and had the appearance of layering in the atheroma similar to thrombus formation. In summary, plaque disruption and subsequent thrombus formation can be demonstrated in vivo by intracoronary ultrasound. Monitoring this process may have important clinical significance in patient management and in assessing clinical prognosis.

Coronary Thrombosis↗
PubMed1995

Angiographically 'silent' plaque in the left main coronary artery detected by intravascular ultrasound.

BACKGROUND: Left main coronary artery (LMCA) atherosclerosis is a high-risk disease but its occurrence is often underestimated by coronary angiography. Intravascular ultrasound (IVUS) has been shown to be more accurate and sensitive than coronary angiography in identifying coronary atherosclerotic lesions. METHODS: Ninety-two patients (55 men and 37 women, aged 55.4 +/- 10.4 years) found to have angiographically normal coronary arteries or ambiguous lesions of the LMCA were examined by IVUS after diagnostic cardiac catheterization. The cross-sectional areas of the vessel, lumen, and atherosclerotic plaque (if any) of the LMCA were determined and the percentage area and diameter of stenosis were calculated. RESULTS: Atherosclerotic plaques in the LMCA were detected in 31 of the 92 patients (34%); 83% of the plaques were eccentric, and 17% contained calcium deposits. In patients with plaques detected by IVUS, the vessel area was 23.3 +/- 6.1 mm2. The plaque area was 6.3 +/- 3.3 mm2 (1.8-16.7 mm2). The area of stenosis was 31.6 +/- 12.1% (12-57.2%). The diameter of stenosis was 19.3 +/- 7.2% (8.7-34.6%). The area of stenosis was over 50% in four patients. The vessel area (23.3 +/- 6.1 mm2) in patients with plaques was larger than that in those without plaques (19.0 +/- 6.5 mm2, P < 0.01). CONCLUSION: Coronary angiography considerably underestimates the occurrence of atherosclerotic stenoses in the LMCA because of coronary remodelling and methodological limitations. The greater sensitivity and accuracy of IVUS in detecting LMCA lesions, at both early and advanced stages, is of great clinical importance in patient management.

Adult↗
PubMed1995

High wall shear stress proximal to myocardial bridging and atherosclerosis: intracoronary ultrasound and pressure measurements.

BACKGROUND: Studies have shown that myocardial bridging may prevent coronary atherosclerosis and that the segment proximal to the bridge is often sclerosed. The underlying mechanism is still unknown. METHODS: Intracoronary ultrasound and pressure measurements were performed in a patient with myocardial bridging in the left anterior descending coronary artery. A 3.5 F, 20 MHz probe was used to measure the change in cross sectional area of the lumen during the cardiac cycle. Intracoronary pressure was measured with a Double tip, end mounted pressure transducer system, the catheter having two pressure sensors located at the end of the catheter 3 cm apart. Intracoronary pressure was recorded as the catheter was slowly advanced and pulled back through the left anterior descending coronary artery. RESULTS: Systolic compression of the bridge segment was clearly visualised on ultrasonography and an eccentric plaque with calcium deposit was found in the segment proximal to the bridge. The pressure in the segment proximal to the bridge (160/26 mm Hg) was higher than that of the proximal normal segment (126/68 mm Hg). The pressure distal to the bridge was 68/30 mm Hg. A highly characteristic "sucking effect" was found in the bridge segment. The pressure in the bridge segment was 102/-40 mm Hg. CONCLUSION: The pressure in the segment proximal to the myocardial bridging was higher than aortic pressure. Disturbance of blood flow and high wall stress proximal to myocardial bridging was a main contributor to the development of atherosclerosis in the segment proximal to the bridge.

Aged↗
PubMed1995

Initial experience with a steerable intravascular ultrasound catheter in the aorta and pulmonary artery.

The aim of this protocol was to test the feasibility and safety of a prototype steerable intravascular ultrasound (IVUS) catheter (Boston Scientific, Waterton, MA) in comparison with standard IVUS catheters. A 3.5F, 20-MHz mechanical echo transducer was incorporated into a bendable sheath with a blunt tip. The flexible IVUS catheter was compared with a standard IVUS catheter in 13 patients. Seven patients underwent catheterization of the left side of the heart, and six patients had catheterization of the right side of the heart for suspected recurrent pulmonary embolism. In the aorta, three lumen area measurements were made: (1) midway between the aortic arch and the aortic root, (2) at the most cranial part of the aorta, and (3) in the descending aorta at the level of the diaphragm. Evaluation of the accuracy of luminal dimension measurements by both types of catheters in perpendicular positions to the vessel wall was evaluated in a hollow rubber cast of an human aorta and its side branches, representing luminal diameters from 3 to 26 mm. We performed 20 measurements with each type of catheter. The results were compared with ruler measurements, after the cast had been cut in slices. The equation for the standard 3.5F IVUS catheter was: y = 0.89x + 0.15; SE = 0.17; r = .97; for the 4.8F 20-MHz standard IVUS catheter: y = 0.97x + 0.05; SE = 0.18; r = .98; and for the steerable catheter, y = 0.94x + 0.09; SE = 0.12; r = 0.97.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗