Intracoronary beta-irradiation with a liquid (188)re-filled balloon: six-month results from a clinical safety and feasibility study.

BACKGROUND: Coronary irradiation is a new concept to reduce restenosis. We evaluated the feasibility and safety of intracoronary irradiation with a balloon catheter filled with (188)Re, a liquid, high-energy beta-emitter. METHODS AND RESULTS: Irradiation with 15 Gy at 0.5-mm tissue depth was performed in 28 lesions after balloon dilation (n=9) or stenting (n=19). Lesions included 19 de novo stenoses, 4 occlusions, and 5 restenoses. Irradiation time was 515+/-199 seconds in 1 to 4 fractions. There were no procedural complications. One patient died of noncardiac causes at day 23. One asymptomatic patient refused 6-month angiography. Quantitative angiography after intervention showed a reference diameter of 2. 77+/-0.35 mm and a minimal lumen diameter of 2.36+/-0.43 mm. At 6-month follow-up, minimal lumen diameter was 1.45+/-0.88 mm (late loss index 0.57). Target lesion restenosis rate (>50% in diameter) was low (12%; 3 of 26). In addition, we observed 9 stenoses at the proximal or distal end of the irradiation zone, potentially caused by the short irradiation segment and the decreasing irradiation dose at its borders ("edge" stenoses). The total restenosis rate was 46% and was significantly lower (29% vs 70%, P=0.042) when the length of the irradiated segment was more than twice the lesion length. CONCLUSIONS: Coronary irradiation with a (188)Re-filled balloon is technically feasible and safe, requiring only standard percutaneous transluminal coronary angioplasty techniques. The target lesion restenosis rate was low. The observed edge stenoses appear to be avoidable by increasing the length of the irradiated segment.

A randomized trial of elective stenting after balloon recanalization of chronic total occlusions.

OBJECTIVES: The aim of this study was to assess the role of Wiktor stent implantation after recanalization of chronic total coronary occlusions with regard to the clinical and angiographic outcome after six months. BACKGROUND: Beside the common use of stents in clinical practice, the number of stent indications proven by randomized trials is still limited. METHODS: Eighty-five patients with a thrombolysis in myocardial infarction grade 0 chronic coronary occlusion were examined. After standard balloon angioplasty, the patients were randomly assigned to stent implantation, or percutaneous transluminal coronary angioplasty (PTCA) alone (no further intervention). Quantitative coronary angiography was performed at baseline and after six months. RESULTS: The minimal lumen diameter did not differ immediately after recanalization (stent group 1.61 +/- 0.30 mm vs. PTCA group 1.65 +/- 0.36 mm), and increased after stent implantation to 2.51 +/- 0.41 mm. After six months, the stent group still had a significantly greater lumen (1.57 +/- 0.59 vs. 1.06 +/- 0.90 mm; p < 0.01) and a significantly lower restenosis and reocclusion rate (32% and 3%) compared with the PTCA group (64% and 24%); restenosis analysis according to treatment was 72% (PTCA) versus 29% (stent, p < 0.01). Late loss was equal in both groups. At follow-up, the stent patients had a better angina class (p < 0.01), and fewer cardiac events (p < 0.03). A meta-analysis including this trial and three other controlled trials with the Palmaz-Schatz stent showed concordant results. CONCLUSIONS: Stent implantation after reopening of a chronic total occlusion provides a better angiographic result, corresponding to a better clinical outcome with fewer recurrence of symptoms and reinterventions after six months.

Increased endothelin release by cultured human smooth muscle cells from atherosclerotic coronary arteries.

OBJECTIVES: Endothelin, a 21-amino acid peptide initially purified from the medium of cultured endothelial cells, is a potent vasoconstrictor exerting its effects predominantly in a paracrine or autocrine manner. Recent data indicate that endothelin is also synthesized by cultured vascular smooth muscle cells and that endothelin is an effective stimulator of smooth muscle cell proliferation. This study aimed to investigate the endothelin release of cultured human smooth muscle cells, isolated from coronary plaques and from normal coronary tunica media, and to determine circulating endothelin concentrations in patients with coronary artery disease compared to control subjects. METHODS: Coronary plaque material was extracted by thrombendarterectomy during aorto-coronary bypass grafting (n = 19). Segments of normal coronary arteries were obtained at autopsy (n = 33). Cells were isolated by enzymatic disaggregation and identified as smooth muscle cells with antibodies against smooth muscle alpha-actin. Venous blood samples were drawn from patients with coronary artery disease undergoing cardiac catheterization (n = 32) and from control subjects (n = 38). Endothelin concentrations in culture medium and in plasma samples were measured by radioimmunoassay after Sep Pak C18 extraction. RESULTS: Cultured smooth muscle cells, isolated from coronary plaques, released a significantly (P < 0.001) higher amount of immunoreactive endothelin into the culture medium (39.2 +/- 3.9 pg/10(4) cells, mean +/- s.e.m., 31 supernatant samples) than smooth muscle cells from normal coronary tunica media (3.9 +/- 0.8 pg/10(4) cells, 28 samples). Circulating endothelin concentrations were slightly elevated (P < 0.01) in patients with coronary artery disease (3.8 +/- 0.2 pg/ml) compared to control subjects (3.0 +/- 0.2 pg/ml). CONCLUSIONS: These data suggest that the endothelin production is markedly increased in smooth muscle cells of coronary atherosclerotic plaques. The enhanced endothelin release may stimulate smooth muscle cell proliferation in a paracrine or autocrine manner and thus may contribute to the development or progression of coronary artery disease.

Endovascular irradiation with the liquid beta-emitter Rhenium-188 to reduce restenosis after experimental wall injury.

OBJECTIVE: Postinterventional irradiation is a new therapeutic concept in the prevention of restenosis. The liquid beta-emitter Rhenium-188 allows endovascular brachytherapy using a conventional balloon catheter without the problem of centering the radiation source. In an animal model of restenosis the feasibility and the dose dependent effect of intravascular brachytherapy with a Rhenium-188 filled balloon catheter was investigated. METHODS: In 68 male New Zealand White rabbits after endothelial denudation of the right common carotid artery with a Fogarty catheter, endovascular irradiation was performed with a Rhenium-188 filled 3.0-mm balloon catheter using different dosages (0, 7.5, 15, 30, 45 and 60 Gy at the surface of the vessel). Then 4 weeks after the intervention the vessels were excised and histologically analyzed. RESULTS: Whereas at 7.5 Gy the intimal area (median [first quartile; third quartile]) did not differ significantly from the control (0.46 mm(2) [0.33 mm(2), 0.75 mm(2)] vs. 0.49 mm(2) [0.34 mm(2), 0.66 mm(2)]), neointimal hyperplasia was decreased significantly at 15 Gy (0.15 mm(2) [0.04 mm(2), 0.17 mm(2)]) and 30 Gy (0.07 mm(2) [0.04 mm(2), 0. 10 mm(2)]), and completely inhibited at the highest dosages (45 Gy: 0 mm(2) [0 mm(2), 0.04 mm(2)]; 60 Gy: 0 mm(2) [0 mm(2), 0.01 mm(2)]). CONCLUSIONS: Catheter transmitted endovascular irradiation with the liquid beta-emitter Rhenium-188 after vascular injury is feasible and effectively reduced neointimal hyperplasia in hypercholesterolemic rabbits. A significant reduction of the neointimal formation could be found already at a radiation absorbed dose of 15 Gy at the vessel surface. Following a surface dosage of 45 Gy the proliferative response to the vessel injury is almost completely abolished.

A human arterial organ culture model of postangioplasty restenosis: results up to 56 days after ballooning.

BACKGROUND: Restenosis is a reparative process that is activated in response to injury induced by angioplasty. Despite numerous experimental models of restenosis the number of human arterial organ culture systems is very limited and long-term experiences do not exist. METHODS AND RESULTS: During routine nephrectomies parts of the renal arteries of 88 patients were extracted, 47 were suitable for organ culture preparations. Sections were made at 3 mm intervals perpendicular to the vessel wall axis. The arterial segments were treated with 3 mm standard balloon-catheters (Medtronic 14K2030E) for 60 s with 3, 6, 9, and 12 bar. After angioplasty, the organ segments were cultured in a mixture of Waymouth's MB 752/1 and Ham F-12, supplemented with 15% fetal calf serum. After 0, 4, 14, 21, 28, and 56 days the organ cultures were fixed in 4% para-formaldehyde and embedded in paraffin. After staining with a modified elastica-van Gieson technique the intimal wall thickening was analyzed with a computerized morphometric system. For the identification of smooth muscle cells (SMC) a monoclonal antibody against smooth muscle alpha-actin was used. Endothelial cells were identified using an anti-human von Willebrand factor. To determine the number of cells undergoing DNA synthesis, bromodeoxyuridine (BrdU), a thymidine analogue, was added to the culture media 18 h prior to fixation. BrdU was detected with a monoclonal antibody, as secondary antibody a biotinylated horse-anti-mouse antibody was used. After 14, 21, and 28 days in culture BrdU-positive cells were detected in the neointima of the organ cultures, indicating mitotic activity in this area. After 28 and 56 days in culture a clear increase of neointimal thickening was found in the morphometric analysis. By positive reaction with antibodies against smooth muscle alpha-actin these cells were partly identified as SMC. CONCLUSIONS: The organ culture model offers opportunities for in vitro investigations of postangioplasty restenosis. The data emphasize the importance of a relatively late proliferative response of SMC in the human arterial organ culture model.

A coronary porcine organ culture system for studies of postangioplasty cell proliferation.

BACKGROUND: Restenosis after angioplasty is generally considered to be caused mainly by an increased proliferation of smooth muscle cells, but recently this theory has been questioned. METHODS: Fresh hearts of 25 pigs were obtained and the left anterior descending coronary arteries carefully prepared, cut into segments and treated with a 3 mm standard balloon catheter for 60 s with 3, 6, 9 and 12 bar. Immediately after angioplasty the specimens were cultured in a mixture of WM/F-12, supplemented with 15% fetal calf serum. RESULTS: After staining with a modified Verhoeff-van Gieson technique, intimal wall thickening was analysed with a computerized morphometric system. After 14 days in culture, angioplasty with 6, 9 and 12 bar resulted in a significant (P < 0.05) increase of neointimal thickening. After 21 days, a significant increase of neointimal thickening was seen after ballooning with 3, 9 or 12 bar (P < 0.05). After 28 days angioplasty with 3 or 6 bar showed a dose-dependent increase of neointima, which was not further increased after ballooning with 9 or 12 bar. Significance was reached after ballooning with 6, 9 and 12 bar (P < 0.05). Smooth muscle cells were identified with a monoclonal antibody against smooth muscle alpha-actin. Endothelial cells were identified using an anti-human von Willebrand factor. To determine the number of cells undergoing DNA synthesis, bromodeoxyuridine, a thymidine analogue, was added to the culture media 18 h before fixation. It was detected with a monoclonal antibody, with a biotinylated horse-anti-mouse antibody as secondary antibody. After 4 and 7 days in culture bromodeoxyuridine-positive cells were observed, indicating an early proliferative response after angioplasty. CONCLUSIONS: The coronary organ culture model offers opportunities for investigations of complex cellular events that are considered important in the development of restenosis. The data reported emphasize the importance of an early proliferative response of smooth muscle cells after coronary angioplasty, resulting in a significant neointimal thickening.

Local calcification as a determinant of the outcome of excimer laser coronary angioplasty: an in vitro study.

BACKGROUND: Calcification influences the outcome of various angioplasty techniques in the treatment of coronary artery disease. During angioscopic in vitro studies, we observed that dissections and perforations not caused by vessel bending frequently occurred at the boundary areas of plaque and adjacent vessel wall. This study investigated whether this is related to the distribution of calcific deposits. METHODS: Postmortem excimer laser coronary angioplasty (308-nm XeCl) was performed in 51 stenotic coronary arteries. Twenty-three segments were further examined; these consisted of 11 perforations, six dissections, three segments with no ablative effect after the application of 20,000 laser impulses, and three successfully passed stenoses without complications. X-ray diffraction analysis and scanning electron microscopy were performed to detect calcium deposits and their spatial relationship to perforations and dissections. RESULTS: X-ray diffractions analysis detected calcifications in 21 of 23 specimens. Postmortem angiography revealed calcifications only on 11 of 23 segments. Three of 11 perforations were located at the plaque border, as were three of six dissections. In all six complications at the plaque border, x-ray diffraction analysis revealed that the plaque border was identical with a border of calcium deposits. Eight of 11 perforations and three of six dissections could be explained by axis divergence between the laser catheter and the vessel orientation. CONCLUSIONS: Contributing factors for perforations and dissections during excimer laser coronary angioplasty are axis divergence and the distribution of plaque calcification. More sensitive methods are needed to detect local vessel wall calcium in vivo.

High-dose diltiazem prevents migration and proliferation of vascular smooth muscle cells in various in-vitro models of human coronary restenosis.

BACKGROUND: Restenosis after coronary angioplasty is considered to be caused mainly by increased migration and proliferation of smooth muscle cells (SMC). The concept of local, site-specific delivery of pharmacologic therapies has opened the door for new, high-dose drug regimes. METHODS AND RESULTS: SMC were isolated by enzymatic disaggregation with collagenase/elastase from human coronary plaque tissue of 29 patients (pSMC) and post mortem from the coronary media of 33 corpses (mSMC). Endothelial cells were isolated from human umbilical veins by enzymatic disaggregation with collagenase/dispase. By positive reaction with antibodies against smooth muscle alpha-actin and von Willebrand factor cells were identified as SMC or endothelial cells. In proliferation studies 5-150 micrograms/ml diltiazem was added to the culture media of pSMC, mSMC and endothelial cells. After 5 days there was a significant dose-dependent inhibition of cell proliferation (for pSMC with > 50 micrograms/ml, for mSMC with > 25 micrograms/ml, and for endothelial cells with > 5 micrograms/ml). In migration studies the effect of 5-150 micrograms/ml diltiazem on the velocity of migration of pSMC was investigated over a period of 48 h. Administration of diltiazem at concentrations of 100 and 150 micrograms/ml caused a significant inhibition of the migration of pSMC. The cytoskeletal components smooth muscle alpha-actin, vimentin, and alpha-tubulin of pSMC and the expression of von Willebrand factor of endothelial cells were investigated after an incubation period of 5 days with 50 and 150 micrograms/ml diltiazem. In the transfilter coculture model the effect of 50 micrograms/ml diltiazem on mSMC was investigated after mechanical injury of cocultured endothelial cells. Administration of diltiazem at a concentration of 50 micrograms/ml inhibited the development of a neointimal proliferate in the transfilter coculture model significantly (P < 0.001). CONCLUSIONS: A high dose of diltiazem inhibited the migratory and proliferative activities of coronary SMC significantly. In further experimental studies the effect of locally applied high doses of diltiazem on postangioplasty restenosis should be elucidated.

A prescreening system for potential antiproliferative agents: implications for local treatment strategies of postangioplasty restenosis.

BACKGROUND: Recent advances in the understanding of the biology of restenosis indicate that it is predominantly caused by a multifactorial stimulation of smooth muscle cell proliferation. The aim of this study was to investigate the in vitro effect of five potential antiproliferative agents on smooth muscle cells from human atherosclerotic femoral arteries. METHODS AND RESULTS: Primary stenosing plaque material of 24 patients (aged 63 +/- 14 years) and restenosing plaque material of 7 patients (aged 65 +/- 9 years) was selectively extracted from femoral arteries by the Simpson atherectomy device. Cells were isolated by enzymatic disaggregation and identified as smooth muscle cells by positive reaction with smooth muscle alpha-actin. Dalteparin sodium (0.001-100 anti-Xa units/ml), cyclosporine A (0.005-500 micrograms/ml), colchicine (0.00004-4 pg/ml), etoposide (0.002-200 micrograms/ml), and doxorubicin (0.0005-50 micrograms/ml) were added to the cultures. Six days after seeding, cells were trypsinized and cell number was measured by a cell counter. All five agents tested exhibited a significant inhibition of smooth muscle cell proliferation (P < 0.001). After an incubation time of 48 h, the cytoskeletal components, alpha-actin, vimentin, and microtubules were investigated. At peak concentrations, all five tested agents except dalteparin sodium caused severe damage to the cytoskeleton. CONCLUSIONS: All five potential antiproliferative agents exhibited a significant inhibition of smooth muscle cell proliferation. The development of new intravascular delivery systems may open the way for local antiproliferative treatment strategies in interventional cardiology.

Quantification of mitral and tricuspid regurgitation by the proximal flow convergence method using two-dimensional colour Doppler and colour Doppler M-mode: influence of the mechanism of regurgitation.

In patients with mitral (n=77: organic=49, functional=28) and tricuspid regurgitation (n=55: functional=54) quantified by angiography, the temporal variation of the proximal flow convergence region throughout systole was assessed by colour Doppler M-Mode, and peak and mean radius of the proximal isovelocity surface area for 28 cm/s blood flow velocity were measured. Additionally, the peak radius derived from two-dimensional colour Doppler was obtained. About 50% of the patients with mitral and tricuspid regurgitation showed a typical temporal variation of the flow convergence region related to the mechanism of regurgitation. The different proximal isovelocity surface area radii were similarly correlated to the angiographic grade in mitral and tricuspid regurgitation (rank correlation coefficients 0.55-0.89) and they differentiated mild to moderate (grade < or =II) from severe (grade > or =III) mitral and tricuspid regurgitation with comparable accuracy (82-96%). However, moderate mitral regurgitation due to leaflet prolapse in two patients was correctly classified by the mean M-mode radius and overestimated by both peak radii. Only half of the patients showed a typical variation of the flow convergence region related to the mechanism of regurgitation. The different proximal isovelocity surface area radii were suitable to quantify mitral and tricuspid regurgitation in most patients. However, in mitral regurgitation due to leaflet prolapse the use of the mean M-mode radius may avoid overestimation.

Corticosteroid agents inhibit proliferation of smooth muscle cells from human atherosclerotic arteries in vitro.

We studied the in vitro effect of steroid agents on smooth muscle cells from human atherosclerotic arteries. Recent advances in the understanding of the biology of restenosis indicate that restenosis is predominantly caused by a multifactorial stimulation of smooth muscle cell proliferation. Primary stenosing plaque material of 24 patients (aged 63 +/- 14 years) and restenosing plaque material of 7 patients (aged 65 +/- 9 years) was selectively extracted from femoral arteries by the Simpson atherectomy device. Cells were isolated by enzymatic disaggregation and identified as smooth muscle cells by positive reaction with smooth muscle alpha-actin. The steroid agents prednisolone (0.0075-750 micrograms/ml), hydrocortisone (0.0125-1250 micrograms/ml), and dexamethasone (0.0004-40 micrograms/ml) were added to the cultures. Six days after seeding the cells were trypsinized and the cell number was measured by a cell counter. All three steroid agents exhibited a significant antiproliferative effect on smooth muscle cell proliferation. At high concentrations of hydrocortisone, cytoskeletal elements of smooth muscle cells such as actin, microtubules, and vimentin, were largely altered. Our data indicate that the proliferation of smooth muscle cells from human atherosclerotic arteries in vitro can be inhibited by steroid agents and thus may open the way for local post-angioplasty treatment strategies.

[High field MR imaging: magnetic field interactions of aneurysm clips, coronary artery stents and iliac artery stents with a 3.0 Tesla MR system]. / Hochfeld-Magnetresonanztomographie: Magnetische Anziehungs- und Rotationskräfte auf metallische Implantate bei 3.0 T.

PURPOSE: To evaluate magnetic field interactions of commonly used biomedical implants at 3.0 Tesla. MATERIALS AND METHODS: Fourteen aneurysm clips designed for permanent placement in intracranial aneurysms, 19 coronary artery stents and 20 iliac artery stents were evaluated in an actively shielded compact 3.0 T MR system (Intera, Philips Medical Systems, Best, The Netherlands, length of magnet 1.57 m). The magnetic deflection forces (translational movement) were evaluated as follows: The implants were suspended by a fine string and placed in the magnet bore at the location of the maximum magnetic field gradient. The translational forces F (z) were calculated from the measured angle of deflection from the vertical axis. The magnetic field-induced torque (rotational forces) was evaluated as follows: Each implant was placed in the center of the magnetic bore parallel to the static magnetic field B0 (position 0 degrees ). Any possible displacement of the implant was noted on a millimeter scale and any torque qualitatively evaluated using a 5 point grading scale (0: no torque; + 4: very strong torque). The implant was turned in steps of 45 degrees, and the procedure was repeated to encompass a full 360 degrees rotation. RESULTS: In 52 of the 53 devices tested, the deflection force (deflection angle: range 0-21 degrees, translational force: range 0-3.8 mN) was less than the gravitational force (i.e., the implant's weight). These devices (n = 52/53) did not show any alignment to or rotation in the magnetic field at any of the various 45 degrees -increment positions corresponding to a qualitative torque evaluation of grade 0/4. One device (n = 1/53), an iliac artery stent made of stainless steel (Zenith, Cook, Mönchengladbach, BRD), was found to have deflection forces (deflection angle 88 degrees translational force 299 mN) greatly exceeding the gravitational force as well as a pronounced torque (grade 4/4). CONCLUSION: Out of 53 biomedical implants evaluated for magnetic field interactions at 3.0 T, one iliac artery stent made of stainless steel was found to be potentially unsafe based on ASTM criteria. MR imaging at 3.0 Tesla may be performed safely in patients with any of the other 52 different implants evaluated in this study with respect to magnetic field translational attraction and torque.

[Whole body distribution of Tc-99m-sestamibi after pharmacological stress with arbutamine and dipyridamole compared with resting conditions]. / Ganzkörperverteilung von Tc-99m-Sestamibi nach pharmakologischer Belastung mit Arbutamin und Dipyridamol im Vergleich zum Ruhezustand.

AIM: Arbutamine is a new catecholamine that has been developed as a pharmacologic stress agent for the diagnosis of coronary artery disease. Optionally, it can be used in myocardial scintigraphy. The pharmacologic effect compared to dipyridamole was assessed looking at the whole body distribution of Tc-99m-Sestamibi. METHODS: 9 patients were investigated after injection of Tc-99m-Sestamibi during rest, after infusion of arbutamine, and after vasodilatation with dipyridamole. RESULTS: Infusion of arbutamine results in a measurable diminished radiotracer deposition in the lower limb as compared to dipyridamole. The amount of myocardial activity of Tc-99m-sestamibi, however, is also reduced as shown by the percentage of myocardial activity compared to the whole body distribution (2.5% +/- 0.4% for arbutamine vs. 2.8% = 0.5% for dipyridamole) in addition, the heart/lung ratio is lower after application of arbutamine (12.1% +/- 0.5% vs. 2.4% +/- 0.4%). CONCLUSION: After infusion of arbutamine the percentage of myocardial activity as well as the contrast of the myocardium to the surrounding lungs is decreased as compared to dipyridamole. Further studies should reveal whether this difference is relevant in diagnosing coronary artery disease.

Interventional nuclear medicine in the prevention of restenosis following angioplasty.

Restenosis is an unsolved clinical and economic limitation of angioplasty. Local irradiation is a new concept to overcome this problem. The magnitude of this health problem becomes apparent when one recognizes that 166132 percutaneous transluminal coronary angioplasty (PTCA) procedures were performed in Germany in 1999. Each angioplasty has subsequent costs of 6384 DM, which can be reduced to 2161 DM by 50% restenosis reduction due to irradiation [1]. The number of diagnostic and therapeutic procedures is growing by at least 10% per year.

Quantification of mitral regurgitation--comparison of the proximal flow convergence method and the jet area method.

A total of 92 patients with mitral regurgitation (age 63 +/- 13 years, 51 men, 41 women), quantified by angiography, were studied using color-flow Doppler imaging of isovelocity surface areas in the flow convergence region proximal to the regurgitant orifice (PISAs) and of the regurgitant jet in the left atrium. The PISA radii for the flow velocities (aliasing borders) of 28 and 41 cm/s, jet area, jet length, and relation of jet area to left atrial area were measured. A proximal flow convergence region was imaged in 98% (85%) of all patients for a flow velocity of 28 (41) cm/s. A regurgitant jet could be visualized in all patients. The PISA radii for both flow velocities correlated more closely with the angiographic grade (rSp = 0.79 for both flow velocities) than the jet area (rSp = 0.43), jet length (rSp = 0.39), and relation of jet area to left atrial area (rSp = 0.37). A correct differentiation of grade I-II from grade III-IV mitral regurgitation was provided in 95% of the patients by the proximal flow convergence method for both flow velocities and in up to 78% of the patients by the jet area method using the uncorrected jet area. The PISA radii correlated weakly with the parameters from the regurgitant jet (r = 0.5-0.58). It can be concluded that the proximal flow convergence method and the jet area method reach comparable sensitivity for the detection of mitral regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac vulnerability assessment from electrical microvariability of high-resolution electrocardiogram.

Patients susceptible to malignant arrhythmias often have an increased beat-to-beat variation of the T-wave of the electrocardiogram. Variability analysis of the T-wave is increasingly used for non-invasive risk assessment. The aim of this study is to evaluate intra-QRS beat-to-beat signal variation and to compare it to ST-T variation. The beat-to-beat, microvolt variation of the QRS and the ST-T segment from 44 patients with coronary heart disease at high risk of suffering from malignant arrhythmias and from 51 healthy volunteers are compared. Variation analysis is carried out on 250 consecutive sinus beats from high-resolution electrocardiograms. The individual beats are filtered using a waveform-independent, cubic spline-filter. A variability index of the QRS and ST-T segments is calculated as the integrated standard deviation of corresponding samples inside the area of interest. Patients at risk of suffering from malignant arrhythmias have a significantly higher variability index of both the QRS (median 44.5 ms against 34.7 ms, p < 0.001) and the ST-T segment (median 20.5 ms against 9.8 ms, p < 0.001) compared to the group of healthy subjects. The discriminative ability of the odds variability indices of the QRS and ST-T segments are not statistically different, the ratios being 7.8 (QRS) and 12.6 (ST-T). We conclude that patients at high risk of suffering from malignant arrhythmias are characterised by an increased beat-to-beat microvolt variation of both the QRS and the ST-T segment. Further studies are necessary to evaluate the prognostic potential of depolarisation variability.

[Colloid osmotic pressure--a parameter of postoperative protein therapy. A pilot study]. / Kolloidosmotischer Druck--Ein Parameter zur postoperativen Eiweisstherapie. Eine Pilotstudie.

120 intensive-care patients were examined postoperatively in a pilot study. The patients were divided into two groups. In group 1 human albumin was given when the serum protein concentration decreased below 5 g%, in group 2 when the colloid osmotic pressure (COP) decreased below 27 cmH2O. Patients of group 2 received less human albumin, but despite the lower human albumin supply these patients did not worse postoperatively as compared to group 1. On the contrary, the trend could be observed that the periods of ventilation were shorter (possibly due to the lower volume load of the patients) and the serum creatinine concentrations were lower (possibly due to the increased supply of crystalloid solutions) if smaller amounts of albumin were given. It may be concluded that the postoperative human albumin supply is unnecessary if the COP ranges 27 cmH2O or more.

[Ultra-thin, flexible ureteropyeloscopy: a new diagnostic possibility. An animal experiment and clinical pilot study]. / Ultradünne, flexible Ureteropyeloskopie: eine neue diagnostische Möglichkeit. Eine tierexperimentelle und klinische Pilotstudie.

Recent advances in fiberoptic technology have resulted in the development of fiberscopes with an outer diameter of less than 6 F and an irrigating or working channel. The feasibility, conditions and benefit of ureteropyeloscopy with ultrathin, flexible endoscopes were evaluated in two sets of investigations: (1) in 6 pigs and (2) in 12 patients during routine retrograde pyelography. Prototypes of flexible endoscopes with a passively deflectable tip, an outer diameter of 5.5 F (1.8 mm) and a 1.5 F (0.5 mm) channel were used. Fine-needle aspiration cytology is possible through the channel under endoscopic control. At present, the lack of maneuverability and the fragility of the fiberscopes limit this method. Its use in the clinical routine, in addition to retrograde ureteropyelography, under local anesthesia is of great promise, however.