High-volume nonionic dimeric contrast medium: first experiences during complex coronary interventions

Interventional cardiology is a rapidly developing field of medicine with annually increasing numbers of coronary interventions. Especially through the development of alternative techniques for coronary angioplasty, new indications have been found and more difficult lesions are tackled. Inevitably, such complex interventions are time-consuming and require high amounts of contrast medium. Newer, mostly nonionic agents have been developed with improved tolerability as well as fewer cardiac and renal side effects due to their nonionic, hydrophilic structure, and their osmolality isotonic to plasma. This study sought to investigate the effects of high-volume nonionic, dimeric contrast medium during coronary interventions with special emphasis on renal and hemodynamic side effects during routine hospital stays. Retrospectively, 25 consecutive patients (age 56 +/- 10 yr) with normal renal and cardiac function receiving > 500 ml of the nonionic dimeric contrast medium iodixanol during complex coronary interventions were analyzed. The analysis was based on serum creatinine levels 1 day before and 2 days after contrast medium administration for the monitoring of renal function. Additionally, heart rate and left ventricular pressures were evaluated before and after left ventricular angiography. Mean serum creatinine rose from 0.9 +/- 0.2 mg/dl to 1.1 +/- 0.2 mg/dl (P < 0.05) after 2 days of coronary intervention. Heart rate, left ventricular systolic pressure, and left ventricular end-diastolic pressure did not change significantly. No major side effects were encountered in the short follow-up period of 2 days. Based on this retrospective analysis, high-volume nonionic, dimeric contrast medium administration in patients without preexisting renal insufficiency is associated with little impairment of renal function, and has only minor hemodynamic and general side effects. Iodixanol 320 mg I/ml is well-tolerated and effective for the use of cardioangiography. Given the limitations of this retrospective analysis, future prospective studies should systematically address the effects of high-volume contrast medium administration in otherwise healthy patients as well as in high-risk patients undergoing coronary interventions.

Non-invasive assessment of cardiac physiology by tissue Doppler echocardiography. A comparison with invasive haemodynamics

BACKGROUND

Tissue Doppler echocardiography reveals characteristic patterns of myocardial velocities within systole and diastole which are not well understood.

AIM

The purpose of this study was to determine the relationship of myocardial velocity patterns, as assessed by tissue Doppler echocardiography, to the contraction and relaxation phases of the cardiac cycle, as determined during cardiac catheterization.

METHODS

Recordings of left ventricular/aortic and left ventricular/pulmonary wedge pressures were obtained simultaneously with apical tissue Doppler echocardiographic images of the left ventricle. A total of 210 cardiac cycles from 22 patients (mean age 58 years, 18 male) undergoing cardiac catheterization were analysed. The time intervals of the different phases of the cardiac cycle were measured from the pressure tracings. These time intervals were correlated to the interfaces of colour myocardial velocity patterns obtained by M-mode tissue Doppler echocardiography.

RESULTS

There was a good correlation between the time intervals assessed haemodynamically and those based on the different velocity interfaces obtained with M-mode tissue Doppler echocardiography. Comparable time intervals (from the R wave) obtained by pressure recordings and tissue Doppler echocardiography were, respectively: isovolumic contraction (70 +/- 14 vs 67 +/- 9 ms, r = 0.79); rapid ejection (206 +/- 54 vs 202 +/- 49 ms; r = 0.95); late ejection (357 +/- 36 vs 346 +/- 42 ms. r = 0.93); isovolumic relaxation (405 +/- 43 vs 409 +/- 56 ms; r = 0.95); rapid filling (514 +/- 67 vs 523 +/- 64 ms, r = 0.91); diastasis (697 +/- 153 vs 709 +/- 146 ms, r = 0.98); atrial contraction (890 +/- 128 vs 899 +/- 132 ms, r = 0.96).

CONCLUSION

Tissue Doppler echocardiography has the potential to accurately measure the different phases of the cardiac cycle which until now could only be determined invasively. It may provide a sensitive method for the assessment of changes in both cardiac contraction and relaxation in different clinical settings.

Intravascular ultrasound in patients with acute pulmonary embolism after treatment with intravenous urokinase and high-dose heparin

OBJECTIVE

To compare the diagnostic value of intravascular ultrasound (IVUS) with angiography in patients with pulmonary embolism.

DESIGN

Open, prospective clinical study.

SETTING

Two university hospitals.

PATIENTS

Angiography and IVUS were used in 11 patients (5 men) (mean (SD) age 50 (18) years) with acute pulmonary embolism.

INTERVENTIONS

At a mean (SD) of 6 (4) hours after thrombolytic therapy with urokinase and full-dose heparin, all patients underwent pulmonary artery angiography. Then 3.5 F mechanical, 20 or 30 MHz IVUS catheters were advanced into the pulmonary circulation.

MAIN OUTCOME MEASURES

The pulmonary circulation was studied by both methods to detect the presence of thrombus, and a modified Miller score (assessing perfusion defects only and not velocity of flow) was used to quantify the angiographic images.

RESULTS

The modified Miller score was mean (SD) 7.4 (2.3) points. 168 pulmonary artery segments (diameter range 2-14 mm) were studied by angiography and IVUS. On angiography, seven segments showed complete obstruction and 49 partial obstruction; 112 were normal. Two distinct types of thrombus formation were found by IVUS. Type A thrombus only partly adhered to the wall but otherwise was mobile and type B predominantly adhered to the wall. IVUS confirmed all seven angiographically complete obstructions but missed three (6%) of the 49 partial occlusions. Forty (87%) of the remaining 46 segments had type A thrombus and six (13%) type B. IVUS indicated a thrombus in 38 (34%) of the 112 angiographically normal segments; 20 (53%) showed a type A pattern and 18 (47%) a type B pattern (P < 0.001).

CONCLUSION

IVUS was more sensitive than angiography in detecting thrombus but the clinical impact of this finding is not clear as yet.

Autoradiographic mapping of brain 5-HT2A binding sites in P and in AA alcohol-preferring rats

There is considerable evidence for an involvement of serotonergic mechanisms in the control of alcohol consumption. In the present study, an extensive 5-HT2A receptor autoradiographic investigation was carried out in two genetically selected rat strains, P and AA alcohol-preferring rats, respectively, as well as in the corresponding NP and ANA alcohol-nonpreferring rats. The aim was to determine if there is any common pattern in 5-HT2A binding site densities that may illuminate mechanisms of alcohol preference in these animals. For quantitating 5-HT2A binding sites, [3H]ketanserin (2 nM) was used. Nonspecific binding was measured in the presence of methysergide 10(-6) M. Results demonstrated a lower level (from 50 to 70%) of 5-HT2A binding sites in the layer IV of prefrontal cortex, frontal cortex, parietal cortex of P rats compared to NP controls. Similarly, in the claustrum, 5-HT2A binding density of P rats was 50% lower than that of NP rats, although this failed to achieve statistical significance. No difference was detected in the other areas investigated, including the olfactory tubercles, nucleus accumbens, caudate putamen, pyriform cortex, ventral tegmental area, temporal cortex, and entorhinal cortex. In AA rats, [3H]ketanserin binding density measured in these brain areas was very similar to that observed in ANA nonpreferring controls, and statistical analysis did not reveal any significant difference between the two rat lines. The present study confirms previous reports demonstrating lower densities of 5-HT2A binding sites in the P rats and provides the first autoradiographic evidence showing that such an alteration does not occur in AA rats. These findings suggest that the expression of high alcohol preference in genetically selected P and AA rats is not associated with a shared neurochemical alteration of the 5-HT2A receptor system.

Autoradiographic distribution of [3H]-(S)-zacopride-labelled 5-HT3 receptors in human brain

Autoradiographic binding studies using the 5-HT3 (5-hydroxytryptamine3) receptor radioligand, [3H]-(S)-zacopride (0.5 nM), identified a heterogeneous distribution of specific binding sites (defined by granisetron, 1 microM) throughout the human brain. Highest radiolabelled 5-HT3 receptor densities were detected in discrete nuclei within the brainstem (nucleus tractus solitarius, area postrema, spinal trigeminal nerve nucleus; 50-200 fmol/mg tissue equivalent) with more modest levels of expression in the forebrain (e.g. hippocampus, nucleus accumbens, putamen, caudate; 4-17 fmol/mg tissue equivalent). Within the hippocampal formation, radiolabelled 5-HT3 receptors were differentially distributed with highest levels in the granule cell layer of the dentate gyrus. Saturation studies with [3H]-(S)-zacopride (0.05-16 nM; non-specific binding defined by granisetron, 10 microM) binding to homogenates of human putamen indicated that [3H]-(S)-zacopride (0.05-16 nM; non-specific binding defined by granisetron, 10 microM) binding to homogenates of human putamen indicated that [3H]-(S)-zacopride labelled an apparently homogenous population of binding sites (Bmax = 72 + 7 fmol mg-1 protein, pKd = 8.69 +/- 0.09, Hill coefficient = 0.99 +/- 0.06, mean +/- SEM, n = 4). The pharmacological profile of [3H]-(S)-zacopride binding to homogenates of putamen indicated the selective labelling of the human variant of the 5-HT3 receptor. The marked differences, however, in the pharmacology (e.g. low affinity for D-tubocurarine) and relative distribution (e.g. presence of 5-HT3 receptors in the human extrapyramidal system) of 5-HT3 receptors in the human forebrain when compared with other species further necessitates caution in predicting clinical responses based on data generated in animal models of disease.

A biomechanical analysis of the stability of titanium bone fixation systems in proximal phalangeal fractures

Apex bending and torsional loading were utilized to study the effects of different plate design and thickness, and screw size and design on the rigidity and strength of seven different titanium mini- and microplates placed onto osteotomized proximal phalanges. One hundred forty-four fresh frozen human cadaveric proximal phalangeal bones underwent a mid shaft osteotomy followed by application of one of the following plates: (1) Synthes linear 1.5-mm five-hole plates, (2) Leibinger linear 1.2-mm five-hole or (3) 1.7-mm four-hole plates, or (4) Leibinger three-dimensional 1.2-mm four-hole, (5) 1.2-mm eight-hole, (6) 1.7-mm four-hole, or (7) 1.7-mm eight-hole plates. Three-point bending (apex dorsal or apex volar) and torsional loading were utilized for each plating configuration. Analysis of variance models of bone specimen width, depth, cortical thickness, and length revealed that increasing plate thickness was associated with increasing rigidity, but that the three-dimensional design yielded a higher relative rigidity except under apex volar loading.

A comparative biomechanical analysis of resorbable rigid fixation versus titanium rigid fixation of metacarpal fractures

Linear (two-dimensional) and three-dimensional (3D) plating systems (Poly-Medics) composed of the resorbable copolymer of polyglycolic acid (PGA) and poly-l-lactic acid (PLLA) (Lactosorb) were studied in vitro. The plates were applied to osteotomized fresh frozen human cadaveric metacarpal bones that were then tested for torsional rigidity and three-point bending strength and rigidity. The results were compared to those from another study of two low-profile titanium plating systems (Leibinger and Synthes). Analysis of variance revealed that the linear-flat Lactosorb plate and screws had apex dorsal rigidity and force-to-displacement measurements equal to all but two of the titanium plates (3D). The 3D-flat Lactosorb plate had the highest torsional rigidity of the resorbable system, but it was only moderately rigid compared to the titanium plating systems. This in vitro biomechanical study of the copolymer PGA-PLLA plating system indicates that, in clinical applications, it may be better suited for metacarpal fractures rather than proximal phalangeal fractures due to the lower demands of torsional loading compared to apex bending.

[Superoxide dismutase and malonyl dialdehyde in human pulp tissue]

A total of 21 pulps were collected from 12 inflamed and 9 normal cases. SOD activity and MDA content were identified in the normal and inflamed pulpal tissues. In the inflamed pulpal tissues, SOD activity and MDA content were significantly increased than those in the normal tissues. The results demonstrated that the inflammation of pulpal tissues resulted in the increasing of the reactivity of superoxide radical and lipid peroxide (LPO). The results also indicated that human dental pulp possessed an endogenous defense mechanism to protect the tissue components from the toxic effects of the reactive oxygen intermediates.

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.

[The study of the biological character on the culture of human trabecular meshwork cells in vitro]

PURPOSE

To establish the culture of human trabecular cells in vitro and to study their biological character.

METHOD

The trabecular specimens from human eyes were cultured. The morphologic features of cultured cells were examined by light and electron microscopy, the immunohistochemical characteristics and the proliferative curve of the cultured cells were also investigated.

RESULTS

The primary cells in culture are multiangular or irregular, and the confluent trabecular cells grow as a single cell layer. The junctions between trabecular cells observed most frequently are puncta adherens and gap junction. Trabecular cells showed apical villons projections and had a high density of various organelles. The trabecular cells were stained intensely with monoclone antibodies to fibronection and laminin and NSE. And it had negative reaction to monocolone antibodies to VIII factor. The cultured cells showed a longer doubling time.

CONCLUSION

The culture of human trabecular cells in vitro was established. This was a key step to dissect the trabecular specimen accurately and carefully. According to the different cellular growth patterns and speed, morphologic and immunohistochemical characteristics from that of the near cells, the cultured human trabecular cells can been identified.

[The comparative study of the macular light threshold in the normal and low visual acuity people]

PURPOSE

To test the macular light threshold (MLT) and the change of macular light sensitivity (MLS) in the normal and low visual acuity people.

METHODS

MLT of 93 eyes of the normal and 76 eyes of low visual acuity people was measured with macular threshold test of Humphrey Field Analyzer-640.

RESULTS

1. MLT increases with age, there is a negative correlation between MLS and age 2. MLT of low visual acuity people is significantly higher than that of the normal visual acuity people in the same age group; 3. No significant difference of MLT was found in the four quadrants of visual field in the same age group; 4. No significant difference of MLT was found between male and female.

CONCLUSIONS

MLS of the normal visual acuity people is superior to that of the low visual acuity people; MLS decreases with age.

Assessment of chromatographic peak purity by means of artificial neural networks

An improved chemometric approach is proposed for assessing chromatographic peak purity by means of artificial neural networks. A non-linear transformation function with a back-propagation algorithm was used to describe and predict the chromatographic data. The Mann-Whitney U-test was used for the concluding the purity of the chromatographic peak. Simulation data and practical analytical data for both pure and mixture samples were analysed with satisfactory results. A prior knowledge of the impurity and the related compound is unnecessary when a slight difference between their chromatogram and spectrum exists. The performance on simulated data sets by this approach was compared with the results from principal component analysis.

Equipment configuration and procedures: preferences for interventional microtherapy

Magnetic resonance imaging (MRI), computed tomography, and electron beam tomography scanners are built for radiologic diagnosis. With increasing frequency they are being used in the field of interventional Microtherapy to permit transparent visualization of the therapeutic field. Each of these scanners can be combined with endoscopy, fluoroscopy/digital subtraction angiography, and ultrasound units for hybrid imaging techniques as well as with therapeutic systems like lasers or radiofrequency. MRI affords 3D localization without x-ray exposure. Open access and keyhole imaging allow nearly real time guidance of instruments. Minimally invasive techniques using endoscopes and hybrid tomographic guidance result in improved tip tracking of microinstruments and reduced complications. This safer access into the body will lead to interdisciplinary cooperation with the potential for large cost reductions. This report summarizes our experience regarding which of the hybrid imaging suites is best suited for procedures including among others drug instillations, prosthesis (stent) implantation, or microoperations (endoscopic diskectomy/sequestrectomy), and physiological measurements simultaneously.

Ability of angiotensin II to modulate striatal dopamine release via the AT1 receptor in vitro and in vivo

1. The ability of angiotensin II to modulate dopamine release from rat striatal slices in vitro and in the intact rat striatum in vivo was assessed by the microdialysis technique. 2. In slices of rat striatum, angiotensin II (0.1-1.0 microM) induced a concentration-related increase in endogenous dopamine release which was maximal (approximately 250% above basal levels) within the first 2-4 min of agonist application and subsequently declined to near basal values. The angiotensin II-induced increase in dopamine release was Ca(2+)-dependent and was completely antagonized by the selective AT1 receptor antagonist, losartan (1.0 microM). In contrast, the AT2 receptor antagonist, PD123177 (1.0 microM) failed to modify the angiotensin II-induced response. Neither antagonist alone modified basal dopamine release from striatal slices. 3. In freely moving rats, angiotensin II (1.0-10 microM; administered via the microdialysis probe) induced a concentration-related increase in extracellular levels of dopamine which was maximal (approximately 150% above basal levels) within 20-40 min of agonist application and subsequently declined. The angiotensin II (10 microM)-induced increase in extracellular levels of dopamine was completely antagonized by the AT1 receptor antagonist, losartan (0.1-1.0 microM; administered via the microdialysis probe) but not by the AT2 receptor antagonist, PD123177 (1.0 microM; administered via the microdialysis probe). Neither antagonist alone modified basal extracellular levels of dopamine. 4. Homogenate radioligand binding studies with [125I]-angiotensin II (0.1 nm) identified relatively low levels of specific binding sites in rat striatal homogenates compared to homogenates of pyriform cortex (51.3 +/- 9.2 and 651.3 +/- 55.1 fmol g-1 wet weight, respectively, mean +/- s.e.mean, n = 3; non-specific binding defined by unlabelled angiotensin II). The majority of the specific [125I]-angiotensin II (0.1 nM) binding in the striatal and pyriform cortex homogenates was sensitive to the selective AT1 receptor antagonist, losartan (1.0 microM). 5. In conclusions the present study provides direct evidence that angiotensin II acting via the AT1 receptor subtype facilitates the release of dopamine in the rat striatum in vitro and in vivo. This receptor-mediated response may account for the modulation of dopamine-mediated behavioural responses by antagonists of the AT1 receptor and inhibitors of angiotensin converting enzyme.

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.

[125I]S(-)-zacopride labels a novel 5-hydroxytryptamine sensitive recognition site in rat duodenum and ileum

Autoradiographic binding studies using [125I]S(-)-zacopride (0.1 nM) identified non-5-HT3 specific binding sites (defined by 5-hydroxytryptamine (5-HT), 1.0 microM) in the rat duodenum and ileum and some other peripheral tissues (adrenal gland, liver, stomach, kidney and spleen). In the rat duodenum and ileum, saturation studies with [125I]S(-)-zacopride indicated that the specific binding was saturable and of high affinity to an apparently homogenous population of binding sites (duodenum Bmax = 1.88 fmol/mg, Kd = 0.078 nM; ileum Bmax = 1.60 fmol/mg, Kd = 0.071 nM). Competition studies with slices of either duodenum or ileum indicated that the pharmacology of the [125I]S(-)-zacopride recognition site in both tissues was comparable but differed from all 5-HT receptors and uptake sites reported to date. However, the [125I]S(-)-zacopride recognition site displayed some pharmacological and regional similarity to the 5-HT1P recognition site: The sensitivity of the [125I]S(-)-zacopride binding in the duodenum and ileum to GTP indicates that the radiolabelled recognition site may represent a functional G-protein coupled receptor.

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.

5-HT4 receptor-mediated modulation of 5-HT release in the rat hippocampus in vivo

1. In the present study, the ability of the 5-hydroxytryptamine, receptor (5-HT4 receptor) to modulate the release of 5-HT in the hippocampus of freely-moving rats was investigated by the in vivo microdialysis technique. 2. The 5-HT4 receptor agonist, renzapride (1.0-100 microM, administered via the microdialysis probe) increased extracellular hippocampal levels of 5-HT in concentration-dependent manner (approximately 200% maximal increase). The ability of renzapride (100 microM, administered via the microdialysis probe) to elevate extracellular levels of 5-HT remained in the presence of the selective 5-HT reuptake blocker, paroxetine (1.0 microM, administered via the microdialysis probe). Furthermore, another 5-HT4 receptor agonist 5-methoxytryptamine (5-MeOT; 10 microM, administered via the microdialysis probe, in the presence of the non-5-HT4 5-HT receptor antagonists pindolol (10 microM) and methysergide (10 microM)) maximally elevated extracellular levels of 5-HT by approximately 450% in the rat hippocampus. The elevation of extracellular 5-HT levels induced by either renzapride (100 microM) or 5-MeOT (10 microM) was completely prevented by combined administration of the selective 5-HT4 receptor antagonist, GR113808 (100 nM, administered via the microdialysis probe). GR113808 (100 nM, administered via the microdialysis probe) administered alone, however, reduced extracellular hippocampal 5-HT levels by some 60%. 3. Systemic administration of the 5-HT1A receptor agonist, 8-OH-DPAT (0.1 mg kg-1, s.c.) reduced extracellular levels of 5-HT in the rat hippocampus by approximately 40%. Prior administration of 8-OH-DPAT (0.1 mg kg-1, s.c.), with an associated reduction of extracellular hippocampal 5-HT levels by approximately 40-50%, however, failed to prevent a subsequent elevation of extracellular levels of 5-HT induced by renzapride (100 microM, administered via the microdialysis probe). 4. Systemic administration of the 5-HT4 receptor agonist, renzapride (0.25 and 1.0 mg kg-1, i.p.) increased extracellular levels of 5-HT in the hippocampus in a dose-dependent manner. The higher dose of renzapride increasing extracellular 5-HT levels by some 200%. The selective 5-HT4 receptor antagonist, GR125487D (1.0-100 micrograms kg-1, i.p.) caused a dose-dependent reduction in extracellular levels of 5-HT in the hippocampus (maximally approximately 80% reduction). Prior administration of GR125487D (10 micrograms kg-1, i.p.) prevented the elevation of extracellular levels of 5-HT induced by renzapride (1.0 mg kg-1, i.p.). 5. In conclusion, the present study provides evidence that activation of the 5-HT4 receptor facilitates 5-HT release in the rat hippocampus in vivo.

Alterations in angiotensin AT1 and AT2 receptor subtype levels in brain regions from patients with neurodegenerative disorders

The present studies assessed the levels of [125I][Sar1,ILE8]angiotensin II-labelled angiotensin AT1 and AT2 receptor recognition sites in homogenates of various brain areas (including caudate nucleus, putamen, substantia nigra, hippocampus, frontal cortex, temporal cortex and cerebellum) from patients with clinically diagnosed Parkinson's disease, Huntington's disease and Alzheimer's disease and those from age-, sex- and post-mortem delay-matched neurologically and psychiatrically normal patients. Radiolabelled angiotensin AT1 receptor recognition site levels were significantly decreased by approximately 70%, 70% and 90% in the caudate nucleus, putamen and substantia nigra, respectively, from patients with Parkinson's disease relative to matched controls. Furthermore, radiolabelled angiotensin AT2 receptor levels were decreased by some 60% in the caudate nucleus of patients with Parkinson's disease relative to control patients. In brain tissue homogenates from patients with Huntington's disease, the angiotensin AT1 receptor recognition site levels were decreased by approximately 30% in putamen relative to the control patients whilst angiotensin AT2 receptor levels were increased by some 90% in the caudate nucleus relative to the control patients. In brain tissue homogenates from patients with Alzheimer disease, the angiotensin AT2 receptor recognition site levels were significantly increased by approximately 200% in the temporal cortex relative to the control patients. The present results indicate that the reduction of angiotensin AT1 and/or AT2 receptor recognition site levels in the caudate nucleus, putamen and substantia nigra correlates with the principal neuropathology associated with Parkinson's disease and as such indicates that at least a significant population of angiotensin AT1 and AT2 receptors are located on the human dopaminergic nigrostriatal pathway. In addition, the marked increase in the levels of angiotensin AT2 receptor recognition sites in temporal cortex from patients with Alzheimer's disease correlates with some other markers associated with the renin-angiotensin system previously investigated in tissue from patients with this neurological disease.

Ability of 5-HT4 receptor ligands to modulate rat striatal dopamine release in vitro and in vivo

1. The ability of 5-HT4 (5-hydroxytryptamine4) receptor ligands to modify dopamine release from rat striatal slices in vitro and in the striatum of freely moving rats was assessed by the microdialysis technique. 2. The release of dopamine from slices of rat striatum continually perfused with Krebs buffer was enhanced by 5-HT4 receptor agonists; 5-HT (10 microM), 5-methoxytryptamine (5-MeOT; 10 microM), renzapride (10 microM) and (S)-zacopride (10 microM) maximally increased dopamine release by 133 +/- 5, 214 +/- 25, 232 +/- 29 and 264 +/- 69%, respectively (mean +/- s.e.mean, n = 3-8). The drug-induced responses were maximal within the first 2 min of drug application, and subsequently declined. The non-selective 5-HT3/5-HT4 receptor antagonist, SDZ205-557 (10 microM), failed to modify basal dopamine release from striatal slices but completely antagonized the (S)-zacopride (10 microM)-induced increase in dopamine release. 3. To allow faster drug application, the modulation of dopamine release from rat striatal slices in a static release preparation was also investigated. The 5-HT4 receptor agonist, renzapride (10 microM) also enhanced dopamine release in this preparation (maximal increase = 214 +/- 35%, mean +/- s.e.mean, n = 14), whilst a lower concentration of renzapride (3 microM) was less effective. The renzapride-induced response was maximal within the first 2 min of drug application, before declining. In this preparation, the stimulation of dopamine release by renzapride (10 microM), was completely antagonized by the selective 5-HT4 receptor antagonist, GR113808 (100 nM). In addition, both the Na+ channel blocker, tetrodotoxin (100 nM) and the non-selective protein kinase A inhibitor, H7 (100 nM) completely prevented the stimulation of dopamine release induced by renzapride (10 microM). 4. In vivo microdialysis studies demonstrated that the 5-HT4 receptor agonists, 5-MeOT (10 microM), renzapride (100 microM) and (S)-zacopride (100 microM) maximally elevated extracellular levels of dopamine in the striatum by 220 +/- 20, 161 +/- 10 and 189 +/- 53%, respectively (mean +/- s.e.mean, n = 5-9). A lower concentration of renzapride (10 microM) was less effective. The elevation of extracellular striatal dopamine levels induced by either renzapride (100 microM) or (S)-zacopride (100 microM) were completely antagonized by the non-selective 5-HT4 receptor antagonist, SDZ205-557 (100 microM). In addition, the elevation of extracellular levels of dopamine induced by either 5-MeOT (10 microM) or renzapride (100 microM) was completely prevented by the selective 5-HT4 receptor antagonist, GR113808 (1 microM) and the renzapride (100 microM)-induced response was also completely prevented by the non-selective protein kinase A inhibitor, H7 (1 microM). In this in vivo preparation, both GR113808 (1 microM) and H7 (1 microM), when perfused alone, reduced extracellular levels of dopamine. 5. In conclusion, the present study provides evidence that the 5-HT4 receptor facilitates rat striatal dopamine release in vitro and in vivo.

[Trabeculectomy combined with extracapsular cataract extraction and posterior chamber intraocular lens implantation]

PURPOSE

To evaluate the effect of trabeculectomy combined with extacapsular cataract extraction and posterior chamber intraocular lens implantation (triple surgeries) on the patients of coexisting cataract and glaucoma.

METHODS

18 cases (19 eyes) of coexisting cataract and glaucoma treated by the triple surgeries were reviewed. Mean follow-up was 14.7 months (rangs from 2 to 20 months).

RESULTS

Intraocular pressure was controlled satisfyingly in all cases except one case required additional treatment of the anti-glaucoma drug. 78.9% of patients achieved 0.3 or better visual acuity. The operation complications consist of anterior uveitis and hyphaema. However, all of them were controlled within 14 days.

CONCLUSION

The triple surgeries are safe and have definite effect on controlling the IOP and improving visual acuity.

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.

Novel techniques of coronary artery imaging

Intravascular ultrasound imaging and intracoronary Doppler flow mapping are two new techniques used to diagnose coronary artery disease. One provides detailed information about coronary morphology; the other assesses coronary function. By combining these two techniques, mechanisms of coronary syndromes that were previously unclear can be elucidated. The preliminary use of electron beam computed tomography in scanning of the coronary arteries has demonstrated the potential to identify severe coronary artery disease noninvasively. Coronary arteries can be imaged by intravenous injection of contrast material. Magnetic resonance imaging and positron-emission tomography are also used for the noninvasive visualization coronary arteries. Both techniques have been tested after interventions, which offers the potential to study myocardial function and perfusion.

Has transesophageal echocardiography changed the approach to patients with suspected or known infective endocarditis?

Infective endocarditis is still a great clinical challenge. Its diagnosis is difficult to establish, and mortality has remained around 30%. Early diagnosis and optimal treatment are crucial fo prognosis improvement. Echocardiography plays an indispensable role in the management of this disease, especially with the recently introduced approach, transesophageal echocardiography (TEE). TEE can overcome the limitations of transthoracic echocardiography (TTE) and is superior to TTE in almost every way in providing earlier and more information for the diagnosis and treatment of infective endocarditis. TEE detects valve vegetations with much higher sensitivity and specificity than TTE. It can demonstrate smaller vegetations in the early stage of the disease and vegetations on atypical locations (e.g., mitral valve annulus), and provides detailed characterization of vegetations (e.g., location, size, mobility, and changes during treatment). Such information is of great prognostic value and may help in selecting proper treatment. TEE is more sensitive for detecting complications, such as mitral valve perforation, abscess, and subaortic complications, which respond poorly to medicine and for which timely surgery may be the best treatment. For those with prosthetic valve endocarditis, TEE is especially useful because TTE is greatly limited by the acoustic shadow of prostheses. Both positive and negative results of TEE examination are valuable for confirming or excluding infective endocarditis. TEE also plays a unique role in intraoperative monitoring and can assess surgical results before the chest is closed. TEE has become an invaluable tool for the diagnosis and management of patients with suspected or known infective endocarditis.

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.

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.

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.

Evidence that the atypical 5-HT3 receptor ligand, [3H]-BRL46470, labels additional 5-HT3 binding sites compared to [3H]-granisetron

1. The radioligand binding characteristics of the 3H-derivative of the novel 5-HT3 receptor antagonist BRL46470 were investigated and directly compared to the well characterized 5-HT3 receptor radioligand [3H]-granisetron, in tissue homogenates prepared from rat cerebral cortex/hippocampus, rat ileum, NG108-15 cells, HEK-5-HT3As cells and human putamen. 2. In rat cerebral cortex/hippocampus, rat ileum, NG108-15 cell and HEK-5-HT3As cell homogenates, [3H]-BRL46470 bound with high affinity (Kd (nM): 1.57 +/- 0.18, 2.49 +/- 0.30, 1.84 +/- 0.27, 3.46 +/- 0.36, respectively; mean +/- s.e. mean, n = 3-4) to an apparently homogeneous saturable population of sites (Bmax (fmol mg-1 protein): 102 +/- 16, 44 +/- 4, 968 +/- 32 and 2055 +/- 105, respectively; mean +/- s.e. mean, n = 3-4) but failed to display specific binding in human putamen homogenates. 3. In the same homogenates of rat cerebral cortex/hippocampus, rat ileum, NG108-15 cells, HEK-5-HT3As cells and human putamen as used for the [3H]-BRL46470 studies, [3H]-granisetron also bound with high affinity (Kd (nM): 1.55 +/- 0.61, 2.31 +/- 0.44, 1.89 +/- 0.36, 2.03 +/- 0.42 and 6.46 +/- 2.58 respectively; mean +/- s.e. mean, n = 3-4) to an apparently homogeneous saturable population of sites (Bmax (fmol mg-1 protein): 39 +/- 4, 20 +/- 2, 521 +/- 47, 870 +/- 69 and 18 +/- 2, respectively; mean +/- s.e. mean, n = 3-4). 4. Competition studies with a range of structurally different 5-HT3 receptor ligands indicated that in both rat cerebral cortex/hippocampus and rat ileum homogenates, [3H]-BRL46470 binding exhibited a pharmacological profile consistent with the labelling the 5-HT3 receptor with compounds competing with Hill coefficients close to unity.5 In HEK-5-HT3As cell homogenates, [3H]-BRL46470 and [3H]-granisetron associated rapidly((3.84+/-0.4)106 M-1S-1 and (5.85+/-0.2)106 M-1S-1, respectively, mean+/-s.e.mean, n=3-4) in an apparently monophasic manner. Following the establishment of equilibrium, both [3H]-BRL46470 and [3H]-granisetron at a saturating concentration ([3H]-BRL46470 approximately 16 nM; [3H]-granisetron approximately 18 nM) and at a sub-Kd concentration (approximately 1 nm for both radioligands)dissociated biphasically in HEK-5-HT3As cell homogenates (saturating concentration; [3H]-BRL464704.05 x 10-3+/-2.53 x I0-3 s-1 and 5.83 x 10-5+0.91 x I0-5 s-1; [3H]-granisetron 3.20 x 10-3+ 1.70 x IO-3 s-1 and18.58 x 10-5 +/- 4.19 x I0-5 s-1: sub-Kd concentration; [3H]-BRL46470 2.47 x 10-3+/- 1.18 x 10-3 s-1 and 9.30x 10-5+/-2.59x 10-5 S-1; [3H]-granisetron 65.91 x 10-3+/-22.14x I0-3 s-1 and 49.96x 10-5+/-12.26x 10-5s- 1 mean+/- s.e.mean, n = 4-8) when induced by a 300 fold dilution in ice-cold Tris/Krebs.6 In conclusion, the present study provides evidence that [3H]-BRL46470 specifically labels the 5-HT3receptor in rat cerebral cortex/hippocampus, rat ileum, NG108-15 cell and HEK-5-HT3As cell homogenates, but fails to label the 5-HT3 receptor expressed in human putamen. Whilst the pharmacological profile of the site labelled by [3H]-BRL46470 is directly comparable to that labelled by [3H]-granisetron, [3H]-BRL46470 consistently labelled approximately twice the density of sites compared to [3H]-granisetron in the same tissue homogenates prepared from rat cortex/hippocampus, ratileum, NG108-15 cells and HEK-5-HT3As cells.

The changes of pattern reversal visual evoked potentials in normal infants

PURPOSE

To study pattern reversal visual evoked potential (PVEPs) and determine the developmental character and mature time of visual function in normal infants at different months of age.

METHODS

PVEPs were recorded from 115 normal infants at 3, 6, 9, 12 months age. P1 latency for different checks (1 degree 40', 25', 6') was analyzed and compared to those of normal adults. Changes of N1, N2 latency of PVEPs were also examined.

RESULTS

P1 latency for all checks (1 degree 40', 25', 6') was significantly longer at 3 months than at 6 months of age (P < 0.05), but no significant differences can be seen after 6 months of age for larger (1 degree 40') and intermediate (25') checks (P > 0.05). P1 latency for larger checks (1 degree 40') reached adult level after 3 months of age, but not for the intermediate check (25'), while P1 latency for small check (6') presented the character of fluctuation.

CONCLUSION

The visual system continued to develop after birth and appeared a certain regularity. Our results showed that P1 latency for larger check (1 degree 40') reached adult levels after 3 months of age. But P1 latency for intermediate check still has not reached adult levels after 3 months of age. To determine the age at which adult levels are finally reached, infants of 12 months and older must be tested. The reason why P1 latency for smaller check (6') presented the character of fluctuation should be the temporal tuning function developing much more slowly.

[Reconstruction methods for 3D imaging and quantification of intracoronary ultrasound cross-sectional images using biplanar fluoroscopy. Initial experiences in vitro and in vivo]

In this investigation, we studied the feasibility of 3D-reconstruction from 2D cross-sectional intracoronary ultrasound images. A computer-aided, automated 3D-reconstruction was used to generate cylindrical and sagittal format of vessels in vitro (n = 9) and in vivo (n = 48). Ultrasound 2D-images were acquired with a 20 MHz mechanical intracoronary ultrasound catheter (Boston Scientific). A slow pullback (about 1 mm/s) of the catheter was performed during continuous recording of the ultrasound images. The recorded 2D-images were then fed to an image processing computer. Correction and scaling of the axial vessel dimensions was performed by the assessment of the catheter position in the simultaneously recorded biplane fluoroscopy. Digitized data were then processed to 3D-images with use of voxel space modeling. The 3D-views from any plane can be reconstructed. The in-vitro study demonstrated that the reconstructed images were able to correctly portray the pathological changes of the vessel wall in all specimen as proved by pathologic examination. In the in-vivo study, 3D-reconstruction provided not only a spatial visualization of the coronary arterial disorders (such as coronary aneurysm, coronary dissection, spontaneous plaque rupture etc.) but also provides the potential to quantify the mass of lesions. By combining sagittal and cylindrical views, 3D-reconstruction enables longitudinal and orthogonal imaging of the both the vessel lumen and vessel wall, therefore, it has the advantage of cross-sectional viewing as obtained from intracoronary ultrasound and the longitudinal viewing as derived from coronary angiography. These preliminary results of the study indicate that 3D-reconstruction of coronary segments is a promising technique for studying coronary artery disease. Analysis can be based not only on single or multiple cross-sectional images but also on vessel segments facilitating serial studies as for instance studies assessing the progression and regression of atherosclerosis.

Three-dimensional reconstruction of coronary arteries with intravascular ultrasound

Three-dimensional (3D-) reconstruction of intravascular ultrasound (IVUS) images is a recently introduced technical method which has rapidly grown in science and clinical practice. In the catheterization laboratory it is particularly important to obtain the 3D-reconstruction on-line, since the dimensions measured and the plaque attributes displayed may guide the therapeutic decision. Off-line reconstruction, however, provides very accurate and reproducible area and volume measurements of lumen and plaque and is thus exceptionally qualified for studying progression/regression of atherosclerosis or restenosis after catheter-based interventions. Complementary 3D-reconstruction methods, revealing specific advantages and limitations, meet the requirements by slightly different technical approaches, but each 3D-reconstruction of two-dimensional IVUS images requires some basic procedural steps. The IVUS images can be acquired during continuous or ECG-gated withdrawals of the IVUS imaging catheter. The latter permits even to visualize the cyclic pulsation of the reconstructed arteries. As an alternative approach a sensing device recognizes the insertion depth of the IVUS catheter and permits reliable measurements even during manual handling of the IVUS catheter. A discrimination between the blood-pool and structures of the vascular wall, performed in the digitized images, can be achieved by the application of different techniques. This processing step which is called segmentation and the image acquisition are particularly crucial with regards to the final quality of the 3D-reconstruction. Currently there are still limitations of 3D-IVUS, but a new approach combining data obtained from 3D-IVUS and biplane angiography offers a promising potential to solve most of the remaining problems in the future. Thus, three-dimensional IVUS offers a great clinical and scientific potential since it provides spatial visualization of vascular pathology, longitudinal and volumetric measurement of luminal and plaque dimensions, and facilitated guidance of catheter-based interventions. Assuming a technical development similar to the progress of the previous years. 3D-IVUS has a realistic chance to gain significant importance and to become a routine technique in the future.

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.

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.

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)

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.

[The study of correlation between hemorrheology and fluorescein angiography in open-angle glaucoma]

PURPOSE

To observe the correlation between hemorrheology and arm-retinal filling time of fluorescein angiogaphy in patients with primary open-angle glaucoma.

METHODS

The whole blood apparent viscosity in high (125 S-1), moderate (23 S-1) and low (1.2435 S-1) shear rates, plasma viscosity and hematocrit were measured in 50 cases (50 eyes) with primary open-angle glaucoma whose intraocular pressures were controlled. They also underwent fluorescein angiography. The duration from arm to retina arteria filling was named arm-retinal arteria filling time.

RESULTS

There were positive correlation between the whole blood apparent viscosity in high and moderate shear rates, hematocrit and arm-retinal arteria filling time (P < 0.05-0.005). The higher blood viscosity, the longer arm-retinal arteria filling time.

CONCLUSION

The blood viscosity in patients with primary open-angle glaucoma can affect the arm-retinal arteria filling time of fluorescein angiography. So, the increasing blood viscosity in patients with primary open-angle glaucoma can reduce the blood supply to the optic disc.

Identification of high-risk subgroups in infective endocarditis and the role of echocardiography

The outcome of infective endocarditis remains poor. It has an overall mortality of around 30%, rising in high-risk subgroups to 50% and 100%. The prognosis can be improved by identification of high-risk patients and special management. Patients with infective endocarditis are found to be at high risk for death or serious complications when one or more of the following factors exist: old age (especially > 60 years old), delayed diagnosis, staphylococcal infection, aortic valve endocarditis, large valvular vegetation, congestive heart failure, embolization in the central nervous system or coronary artery, prosthetic valve infection, recurrent events, and failed antibiotic therapy. These factors often coexist and interrelate with one another. Early diagnosis and active treatment are critical for a better clinical outcome. However, infective endocarditis is difficult to diagnose because of the atypical clinical manifestations and frequent negative results from blood culture. Echocardiography plays an indispensable role in the diagnosis and management of suspected or known infective endocarditis. By detecting and monitoring certain pathological changes associated with the disease, e.g. vegetation, abscess formation, or valvular destruction, echocardiography helps to diagnose the disease early, to identify patients at high risk, to monitor the patients, and to optimize the timing and mode of surgical intervention. Serious complications can thus be avoided or cured at an early stage and the prognosis significantly improved.

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.

[Alternative methods in interventional therapy of coronary heart disease]

Percutaneous high-frequency coronary rotablation using the rotablator is able to remove arteriosclerotic material from the vessel wall. A diamond-coated (30-80 microns) brass burr drill fastened to a flexible drive shaft rotating and tracking along a drill coaxial guide wire is used. The turbine rotates the drive shaft in excess of 150,000-190,000 rpm. High-frequency rotational angioplasty was successful in > 90% of patients, but in about 90% additional PTCA is necessary. No increase of bypass surgery compared to PTCA is observed. CK and CR-MB elevation is more often found than after PTCA. Vessel perforation is rarely observed. All vessels were open at 24-h control. The restenosis rate seems not be increased. The main indications for high-frequency rotational angioplasty are rigid and calcified sclerotic lesions which cannot be passed by conventional balloon catheters. Whether the restenosis rate can be reduced by this method will be judged in part by the COBRA study. In order to avoid acute complications of PTCA and to reduce restenosis rate, coronary stents were developed. Self-expandable and balloon expandable stents are available. It could be demonstrated that these stents can be used as a bail-out system and can block elastic recoil of coronary arteries. The major remaining problem is subacute closure of coronary vessels. In order to prevent thrombosis treatment with coumarine, acetylsalicylic acid, and dipyridamol is necessary. Coronary stents can be successfully delivered in more than 90% of the patients. In a highly selected patient group using single stents restenosis rate could be significantly reduced.

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.

A human hybridoma monoclonal antibody (TrJ11) recognizing a new HLA-DR epitope shared by DR4, DR8, DR11, and DRB1*1303

The cytotoxic IgM lambda human hybridoma mAb TrJ11 reacts with lymphoblastoid B-cell lines expressing DR4, DR8, DR11, and DRB1*1303. However, TrJ11 was monospecific when normal B cells freshly isolated from blood served as targets in that it only killed HLA-DR4-positive cells. Thus, of 235 HLA-typed persons TrJ11 was strongly cytotoxic for normal B cells of all 90 DR4-positive individuals, but it did not react with B cells from any of the 145 DR4-negative donors. Hence, mAb TrJ11 proved to be suitable for routine DR4 typing. The specific binding of TrJ11 to a DR4-positive cell line was profoundly blocked by the mouse HLA-DR beta chain-specific monomorphic mAb TAL 14.1, indicating that the epitope recognized by TrJ11 is located in the DR beta chain. The possibility that amino acids located in the floor of the peptide-binding site are critical for the TrJ11 epitope is discussed.