Search PubMed⌕ Search

Biomedical subjects

R Erbel

Publications and source records attributed to R Erbel.

At least 271 records · Page 15Linked to original sources
PubMed1996

Non-invasive assessment of coronary Palmaz-Schatz stents by contrast enhanced electron beam computed tomography.

UNLABELLED: The aim of the study was the evaluation of electron beam computed tomography as a non-invasive method to localize coronary stents and to document patency in stented vessel segments. METHODS: Twenty-two patients (16m/6f, 58 +/- 7.8 years) with coronary Palmaz-Schatz stents were examined. Contrast enhanced electron beam computed tomography using an Evolution scanner (Siemens) and coronary angiography were carried out within 7 days of each other. Stent localization was performed using the single-slice mode of the electron beam computed tomography scanner. Patency of the coronary target segment was assessed using the multi-slice mode after peripheral venous injection of a 40 ml bolus of contrast medium (Ultravist 370). Qualitative image analysis of a cine loop of 10 consecutive frames and quantitative analysis of densitometric curves in a region of interest distal to the stented vessel segment were performed. RESULTS: All stented vessel segments were identified. In 20 patients (91%), qualitative assessment of contrast enhancement patterns enabled stent patency to be evaluated. In 18 patients (90%), contrast medium was visualized distal to the stent. Quantitative coronary angiography confirmed that the stented vessel segments were not stenosed. Densitometric curves obtained in 16 of these 18 patients yielded contrast enhancement distal to the stented vessel segment of 63 +/- 6% compared to the aorta. In one patient, qualitative and quantitative analysis showed prolonged contrast enhancement of reduced density, which hinted at a stenosis related to the stented vessel segment. Coronary angiography revealed subtotal occlusion of the stented vessel directly distal to the stent. In another patient, no contrast visualization of the vessel distal to the stent was achieved. Coronary angiography revealed complete stent occlusion in this case. CONCLUSION: Electron beam computed tomography can reliably localize coronary stents and may become a useful tool for providing information on stented vessel segment patency.

Adult↗
PubMed1996

The influence of Albunex on the pulmonary circulation in patients with pulmonary hypertension or left heart failure.

To determine the safety of the ultrasound contrast agent Albunex, its influence on right and left heart haemodynamics in patients with pulmonary artery hypertension or left heart failure was assessed after intravenous injection. Patients with a left ventricular ejection fraction smaller than 40% or a systolic pulmonary artery pressure greater than 40 mmHg received 0.08 and 0.22 ml.kg-1 Albunex and 10 ml albumin in random order during right heart catheterization and transthoracic echocardiography. Right atrial, systolic and diastolic pulmonary artery and capillary wedge pressures were measured at 3 min and 5 min and cardiac output at 5 min after the intravenous injection of Albunex and control. The mean differences of pre- and postinjection values and their confidence intervals were tabulated and significance was anticipated if the confidence interval did not include 0. Significant changes to pre-injection values could be observed in diastolic pulmonary artery pressure 5 min after the injection of albumin and 0.08 ml.kg-1 Albunex, and in right atrial pressure 5 min after the injection of 0.22 ml.kg-1 Albunex only. Since intermediate opacification of the left ventricle was seen in only four patients with 0.22 ml.kg-1 Albunex, in the patients studied higher doses of Albunex and their safety need to be assessed.

Albumins↗
PubMed1996

Differences in the morphology of unstable and stable coronary lesions and their impact on the mechanisms of angioplasty. An in vivo study with intravascular ultrasound.

The aim of this study was to compare the morphology of stable and unstable coronary lesions using intravascular ultrasound in patients undergoing coronary balloon angioplasty and to determine whether lesion morphology had any influence on the mechanism of balloon angioplasty. Thirty three (15 stable and 18 unstable) patients undergoing single lesion percutaneous transluminal coronary angioplasty were studied with intravascular ultrasound before and after intervention. All examinations, recorded on S-VHS video tape, were studied off-line and matched sites from the point of minimum lumen area after the procedure and the corresponding site prior to intervention were compared. The morphology of lesions before intervention was noted and the mechanisms of angioplasty (vessel stretch, lesion remodelling and lesion tears) were determined by comparing pre- and post-interventional morphology and dimensions. The only significant morphological difference between stable and unstable lesions was the presence of a demarcated inner layer in unstable lesions, delimited by a fine circumferential line. This pattern was noted in 77% (14/18) of unstable lesions and in 7% (1/15) of stable lesions (P < 0.01). Unstable lesions tended to have more echolucent zones than stable lesions (72% (13/18) vs 46% (7/15), P = 0.13). The mechanisms of angioplasty were also found to differ. Whereas lesion remodelling (or 'compression') was seen in 77% (14/18) of unstable lesions, it occurred in only 13% (2/15) of stable lesions and mean lesion cross-sectional area reduction was greater in unstable lesions, - 14.8 +/- 8.3% (2.1 +/- 1.3 mm2) compared to stable lesions, - 4.1 +/- 8.4% (0.42 +/- 0.9 mm2), P < 0.01. In contrast, vessel stretch was seen more frequently in stable lesions (73%, 11/15) compared to unstable lesions (22%, 4/18) P < 0.01 and the mean increase in vessel cross-sectional area was + 13.5 +/- 6.8 (1.6 +/- 0.9 mm2) in stable lesions compared to + 5.5 +/- 5.6% (0.8 +/- 0.9 mm2) in unstable lesions, P < 0.01. Lesion tear was present to a similar degree in both groups of patients. In this observational study we found a set of echographic markers that distinguished unstable lesions. The mechanisms of angioplasty differed between stable and unstable angina, with greater lesion remodelling seen in unstable lesions and vessel stretch in stable lesions. Taken together, these findings suggest that the markers we describe may be echographic indicators of mural thrombus.

Angina Pectoris↗
PubMed1996

Value of intracoronary ultrasound and Doppler in the differentiation of angiographically normal coronary arteries: a prospective study in patients with angina pectoris.

BACKGROUND: A substantial proportion of patients undergoing heart catheterization for suspected coronary artery disease have normal angiograms. Coronary morphology and blood flow velocity can be assessed very accurately with intracoronary ultrasound and Doppler. The purpose of this study was to use both methods to classify further patients with suspected coronary artery disease but with coronary angiograms adjudged normal at the time. METHODS AND RESULTS: In forty-four patients with suspected coronary artery disease and normal coronary angiograms, intracoronary ultrasound and intracoronary Doppler were performed in the left anterior descending and left main coronary arteries. Coronary flow reserve was obtained by calculating the ratio of the maximal coronary flow mean velocity after the intracoronary administration of 10 mg papaverine to the coronary flow mean velocity at rest. Of 44 patients, 16 (36%) (group I) were found to have normal coronary morphology by intracoronary ultrasound and normal (> 3.0) coronary flow reserve (5.3 +/- 1.8). In seven patients (16%) (group II) there were normal intracoronary ultrasonic findings but a reduced coronary flow reserve (2.1 +/- 0.4). Plaque formation was found in a total of 21 (48%) of the 44 patients; mean plaque sizes were 3.6 +/- 1.6 mm2 for those in group III (normal coronary flow reserve) and 5.0 +/- 2.3 mm2 for those in group IV (reduced coronary flow reserve). Vessel area in both of these groups (16.3 +/- 8.0 mm2 and 19.2 +/- 6.1 mm2) was significantly larger than that of group I (14.6 +/- 5.7 mm2, P < 0.01). Plaque calcification was found in 25% of those in group III and 44% of those in group IV. Thus, only 36% of the patients with normal angiograms were true normal, 48% exhibited early stage of coronary atherosclerosis, and the other 16% might be considered as syndrome X. CONCLUSION: Intracoronary ultrasound and Doppler can be used to differentiate further heart disease in patients with normal coronary angiograms. Only a minority were true normal. Early signs of atherosclerosis cannot be detected by coronary angiography. This may have important therapeutic and prognostic implications.

Adult↗
PubMed1996

Evaluation of post-myocardial infarction regional and global left ventricular function by monoplane ventriculography: superiority of right versus left anterior oblique projection at any infarct location.

OBJECTIVES: To study the significance of serial quantitative regional wall motion analysis, volumes, and ejection fraction findings as well as their prognostic implications derived from cineventriculography in 30 degrees right anterior oblique (RAO) projection in comparison with 60 degrees left anterior oblique (LAO) projection in post-myocardial infarction patients. Ventriculographic left ventricular parameters are accepted surrogates of mortality in myocardial infarction. Nowadays, in contrast to a biplanar approach in most institutions and clinical trials, the investigation is reduced to monoplanar ventriculography. However, it is not known whether the relevance of the two established projections might differ in different infarct topographies. DESIGN AND METHODS: Two hundred and six consecutive patients with acute myocardial infarction (infarct duration < 6 h) were treated with streptokinase (group I, n = 103) and allocated randomly additional percutaneous transluminal coronary angioplasty (group II, n = 103). Biplanar cineventriculography studies were performed at the acute stage, before discharge, and 6 months after discharge from hospital. RESULTS: Regional wall motion analysis (using an algorithm of fixed radiants) documented larger hypokinetic areas and intensities on RAO than it did on LAO projections, whereby infarct size and its improvement (stunned myocardium) was displayed more comprehensively, and a higher predictive power for survival (P = 0.0002 versus NS) was shown in anterior and inferior infarcts. No advantage of the LAO projection could be detected for evaluation of lateral infarcts due to circumflex coronary artery thrombosis either. The predictive power of the global function (ejection fraction; the algorithm of disc summation method) established by RAO projection (P = 0.007) was superior to that of LAO projection (P = 0.03). Enlargement of volumes (left ventricular remodeling) could be documented significantly only by the RAO projection; the LAO projection failed to do so. Groups I and II did not differ in any respect. CONCLUSIONS: The RAO projection has excellent diagnostic and predictive power at any infarct location. In contrast, additional LAO projection provides little information that cannot be obtained reliably from the RAO projection.

Angioplasty, Balloon, Coronary↗
PubMed1996

Non-invasive visualization of coronary arteries with and without calcification by electron beam computed tomography.

Coronary artery disease (CAD) is one of the leading causes of mortality and morbidity in the western industrialized countries. Recent studies demonstrate the feasability of successful primary and secondary prevention. However, the detection of early stages of coronary artery disease is an unresolved issue. Whereas sensitivity and specificity of traditional risk factor assessment and stress tests are limited, the analysis of coronary calcification allows to obtain a direct sign of coronary atherosclerosis. This concept has been applied using fluoroscopy and conventional computed tomography (CT). However, the exact localization and quantification of coronary calcification only became possible with the advent of electron beam CT (EBCT). This new method showed a high prevalence of coronary calcification in the asymptomatic population. With the definition of a standardized "calcium score" the normal age-specific distribution and amount of coronary calcification was investigated. EBCT proved to be more sensitive in the diagnosis of both non-obstructive and obstructive coronary artery disease than risk factor analysis and stress testing, respectively. Obstructive coronary artery disease, however, cannot yet be predicted with high enough accuracy. A close correlation of EBCT coronary calcification was found to a) the total coronary plaque volume defined by histo-pathology, b) intracoronary ultrasound findings, c) the number of coronary risk factors, d) the coronary prognosis. Using EBCT, a reliable non-invasive identification of persons at risk was obtained for the first time. Guidelines for the use of EBCT in the early diagnosis and treatment of coronary artery disease are being developed.

Adult↗
PubMed1996

Intravascular ultrasound for evaluation of coronary arteries.

Intravascular ultrasound (IVUS) has emerged form a research tool to an intrinsic part of modern invasive cardiology. The main reason is the capability to obtain "in vivo" histology. For the first time it is possible to base decisions not only on lumenograms but also on vessel wall assessment. The capabilities of IVUS can be divided in its (a) diagnostic and (b) intervention associated potentials. Diagnostic strength of IVUS is the ability to monitor compensatory coronary artery enlargement as a response to arteriosclerosis, to assess intermediate lesions, to reveal occult left main stem disease, and angiographycally "silent" arteriosclerosis. The intervention associated 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 luminal gain can be assessed almost on-line. Several groups showed, that the residual plaque area even after angiographycally successful PTCA lies still in the range of 60%. A significant reduction of this number may influence longterm outcome after PTCA. Minimal luminal areas and residual plaque area after PTCA seem to be an indicator of restenosis, while the presence or absence of dissections seem to be less predictive. Intravascular monitoring of stent expansion led to high-pressure stent deployment with significant increase in post-procedural luminal diameters and finally the ability to withhold anticoagulation in patients with optimal stent deployment. In the future, integrated devices, like balloons on intravascular ultrasound catheters, steerable catheters, integrated flow and pressure transducers, tissue characterization, and 0.018 "intravascular ultrasound guide-wires will further enhance the usefulness of IVUS.

Angioplasty, Balloon, Coronary↗
PubMed1996

[Normalization of myocardial perfusion reserve after coronary stent implantation in comparison with balloon angioplasty alone].

Stents scaffold coronary arteries after angioplastic treatment and inhibit elastic recoil resulting in a larger and more circular focal lumen. In 25 patients with significant stenoses of the left anterior descending coronary artery, presenting no collaterals or myocardial infarction, EKG-gated digital subtraction angiograms were recorded at baseline and during hyperemia induced by intracoronary injection of 12 mg papaverine before and after balloon angioplasty, and after adjunct implantation of a single Palmaz-Schatz stent. Densitometric evaluation revealed the time parameters contrast medium appearance time (MCAT) rise time (RT) and mean transit time (MTT) and maximum intensity (Imax). Myocardial perfusion reserve (MPR1) was calculated as the ratio of baseline MCAT and hyperemic MCAT multiplied by the ratio of hyperemic Imax and baseline Imax while MPR2 was calculated as the ratio of baseline RT and hyperemic RT. Maximum flow ratio (MaxFR) was calculated as the ratio of preprocedural hyperemic MTT and postprocedural hyperemic MTT. Post-stenotic MPR1 increased from 1.36 +/- 0.28 to 2.50 +/- 1.20 and to 3.40 +/- 0.58 (ANOVA p < 0.05), while reference MPR1 remained unchanged with 3.40 +/- 0.60. Post-stenotic MPR2 increased from 1.57 +/- 0.14 to 2.59 +/- 0.86 after balloon angioplasty and to 3.10 +/- 0.41 after stenting (ANOVA p < 0.05), while reference MPR2 remained unchanged with 3.10 +/- 0.40. MaxFR was 2.13 +/- 0.53 after balloon angioplasty and 2.83 +/- 0.35 after stenting (p < 0.05). A good correlation was found between minimal stenosis diameter and MPR1 or MPR2 (MPR1: r = 0.94; MPR2: r = 0.87) and between luminal gain and MaxFR (r = 0.75). A negative correlation was measured between recoil, defined as the difference between inflated balloon diameter and resulting minimal stenosis diameter, and MPR1 and MPR2 and MaxFR (MPR1: r = -0.86; MPR2 r = -0.80; MaxFR r = -0.83). In conclusion, adjunct coronary stent implantation normalized post-stenotic myocardial perfusion immediately in contrast to balloon angioplasty alone resulting from a larger postprocedural lumen and a more pronounced inhibition of elastic recoil.

Adult↗
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

[Normal values for dobutamine stress echocardiography].

Dobutamine stress echocardiography having established itself as a sensitive method for diagnosing coronary heart disease, even in the absence of normative values, the physiological haemodynamics as well as the physiological values for global and regional left ventricular myocardial function were measured. TEST PERSONS AND METHODS: 14 healthy subjects (ten men, four women; median age 25 [range 21-32] years) underwent dobutamine stress echocardiography according to an internationally practised dosage steps protocol (5-40 micrograms/kg/min with additional 0.5 mg atropine at 40 micrograms). RESULTS: Maximal infusion rate achieved a serum dobutamine level of 1.67 micrograms/ml with minimal quartiles; it did not influence serum electrolytes (especially potassium). Heart rate increased from 64 to 150/min (P < 0.0001), blood pressure from 111/66 to 158/88 mmHg (systolic: P < 0.0001; diastolic P < 0.001) and the double product of systolic pressure and heart rate from 6714 to 24571 (P < 0.001). While the end-diastolic volume index decreased from 50 to 37 ml/m2 (P < 0.05), the end-systolic volume index fell from 20 to 7 ml/m2 (P < 0.0001). Regional wall motion analysis indicated an increase in left ventricular circumferential contractility with little scatter. CONCLUSIONS: The usual protocol for dobutamine stress echocardiography is a sensible one, because the haemodynamic effect occurs already at low dosage and can then be increased significantly with further dosage steps. High serum dobutamine concentrations can be achieved without arrhythmogenic hypokalaemia. Volume index and ejection fraction are especially discriminatory variables. Quantitative analysis of wall motion is justified because of the low scatter of values.

Adult↗
PubMed1995

[Measuring blood pressure at the wrist: critical analysis of a validation study].

BACKGROUND: The new device "Blood Pressure Watch" (BPW) by NAIS-Matsushita, which measures blood pressure oscillometrically at the hand wrist, is preferred by many hypertensive patients as a device for self-measurements because of its smallness and simple applicability. SUBJECTS AND METHOD: To evaluate the accuracy of blood pressure measurements with this device we determined the blood pressure four times consecutively in the aortic arch using a Statham P23 and the BPW simultaneously at the left hand wrist in 27 patients (58.6 +/- 10.3 [range: 36 to 76] years; 21 male) after a coronary angiography. RESULTS: With a correlation coefficient of 0.85 for systolic and 0.84 for diastolic pressure mean blood pressure was determined higher (systolic: +1.4 +/- 10.1 mm Hg, diastolic: +4.4 +/- 7.6 mm Hg) by the BPW compared to the aortic arch pressure. While there was no correlation between systolic differences and patients' age, it could be demonstrated that with increasing age the BPW exhibited higher diastolic blood pressure values than those measured in the aortic arch. Multiple regression analysis revealed that this was due to inability of the BPW to detect low diastolic blood pressures (r = 0.89, p < 0.001). CONCLUSIONS: 1. For the majority of hypertensive patients the hand wrist device is suitable for self-measurement of blood pressure. It is advisable to perform an auscultatory comparative test at least once before buying such a device. 2. The oscillometric method for measuring blood pressure does not seem to be the proper method for epidemiologic studies and investigation of population groups in which lower diastolic pressure ranges are to assumed.

Adult↗
PubMed1995

[Electron beam tomography in coronary disease. Prevalence and distribution of coronary calcifications and their relationship with coronary risk factors in 650 patients].

OBJECTIVE: The extent of coronary calcification demonstrated by electron beam tomography was correlated with the individual cardiac risk profile. PATIENTS AND METHODS: The possible presence of coronary calcifications was studied by electron beam tomography (EBT) in 650 patients (526 men, 124 women; mean age 54 +/- 10 [28-81] years) with known or suspected coronary heart disease. Depending on the degree of density and the size of the lesion a score was calculated according to an international standard. RESULTS: No calcification was shown to be present in 202 patients (score of 0). A score of more than 0 was calculated in 73.8% of men and 48.4% of women. The average score was 227.8 +/- 24.8 in men, compared with 65.3 +/- 26.5 in women (P < 0.001). There were significantly more calcifications in older patients: Men aged 71-75 years had the highest score, 859.4, while the lowest, 9.6, was in those aged 36 to 40 years. The most important variables for the presence of calcification were age (relative risk per age group: 1.6), male sex (relative risk: 4.3), hypertension (relative risk: 2.4) and nicotine consumption (relative risk: 1.8). The median point score in patients without known risk factors was 1.3, with one known factor it was 7.2, and with three it was 48.0. The vessel segment most affected with calcification was the anterior interventricular branch with an average score of 84. CONCLUSION: Together with an evaluation of the risk profile EBT provided a better assessment of individual risk than conventional examination.

Adult↗