Biomedical subjects

Dietmar Glogar

Publications and source records attributed to Dietmar Glogar.

At least 37 records · Page 2Linked to original sources

PubMed2004

Estimation of doses to personnel and patients during endovascular brachytherapy applications.

In the last few years coronary endovascular brachytherapy using gamma- and beta-emitting radionuclides has been established as a standard treatment procedure to prevent restenosis after percutaneous coronary interventions. Direct measurements and calculations were made to determine personnel doses and organ doses of patients due to gamma rays of 192Ir and beta rays of 90Sr/90Y and 32P sources. In general, our results show that the dose levels are low compared with the X-ray exposure from angiography. The dose rate from bremsstrahlung at 1 m distance from a device containing a 90Sr/90Y source of 2.3 GBq is 4 micro Sv h(-1). The skin dose from beta rays during source transfer into and from the patient was estimated with the directional dose equivalent H'(0.07) of 10 micro Sv at 1 m distance from the catheter. By maintaining safe distances, the dose levels can be kept well within annual dose limits.

Beta Particles↗

PubMed2004

Intracoronary brachytherapy with beta-radiation for the treatment of long diffuse in-stent restenosis.

OBJECTIVE: To assess the efficacy of intracoronary brachytherapy with beta-radiation (Sr/Y) for the treatment of long diffuse in-stent restenosis (ISR). METHODS: As recurrent ISR depends on intimal injury after coronary angioplasty, long in-stent restenotic lesions were defined as lesions with a treatment length >26 mm (lesion length >20 mm plus a treatment margin of 3 mm at each end). Seventy-eight patients with long ISR were treated at our institution with beta-brachytherapy after coronary angioplasty. Patients were irradiated with either an approximate dose of 12 Gy at 1 mm vessel wall depth or with 18 Gy at 1 mm vessel wall depth. Clinical follow-up was available for 69 patients and angiographic follow-up for 65 patients. Late lumen loss (LLL), binary restenosis (stenosis >50%), target lesion revascularization (TLR) and major adverse cardiac events (MACE) were assessed for a follow-up time of 6.6+/-2.2 months. RESULTS: Mean interventional treatment length was 46+/-18 mm. TLR was performed in all 23 patients with binary restenosis (33%). Death of cardiac cause was reported for two patients, one of whom did not undergo TLR. Thus, overall MACE rate was 35%. Recurrent ISR was significantly more frequent in patients with geographic miss. Comparison of the different radiation dose regimens revealed significantly lower LLL in patients irradiated with the higher dose (0.20+/-0.68 mm compared with 0.65+/-0.96 mm, P=0.03). CONCLUSION: Intracoronary brachytherapy with beta-radiation (Sr/Y) is a safe and effective therapeutic option for the reduction of recurrent ISR in long diffuse lesions. We recommend a high-dose irradiation with 18 Gy at 1 mm vessel wall depth.

Aged↗

PubMed2004

Increased dosage during intracoronary irradiation due to overlapped source stepping shows no long-term adverse changes in vessel morphology.

PURPOSE: The purpose of this analysis was to evaluate if overdosage during intracoronary irradiation due to overlapped source stepping may result in long-term morphologic changes in vessel anatomy. METHODS: Baseline angiograms of patients with in-stent restenosis undergoing coronary reintervention followed by intracoronary irradiation with source stepping were analyzed. Overlapping was considered present for the segment with overlapped reference isodose length (RIL) (RIL = segment with > or = 90% of reference dose at 1 mm vessel wall depth). Baseline and 6-months follow-up volumetric intravascular ultrasound (IVUS) analysis were performed for the overlapped segment and for proximal and distal segments of equal length. RESULTS: Overlapping was found in six patients (three patients: (32)P treatment; three patients: (90)Sr/Y treatment); final analysis was performed in four patients. Comparison of the baseline and follow-up IVUS volumetric parameters revealed no significant change in lumen or vessel volumes at segments of overlaps in comparison to proximal and distal reference segments. CONCLUSION: Increased dosage due to overlapping during source stepping is not associated with morphologic changes in vessel anatomy at follow-up.

Angioplasty, Balloon↗

PubMed2004

Electromechanical properties of perfusion/metabolism mismatch: comparison of nonfluoroscopic electroanatomic mapping with 18F-FDG PET.

UNLABELLED: The aim of this study was to compare nonfluoroscopic electroanatomic mapping (NOGA), SPECT perfusion imaging, and PET metabolic imaging for assessment of myocardial viability. In particular, we sought to elucidate differences of electromechanical properties between the perfusion/metabolism mismatch as an indicator of a potentially reversible ischemic injury and the perfusion/metabolism match indicating irreversibly damaged myocardial tissue. METHODS: Twenty-one patients with coronary artery disease underwent NOGA mapping of endocardial unipolar voltage, cardiac 18F-FDG PET of glucose utilization, and resting 201Tl SPECT of myocardial perfusion. RESULTS: Electrical activity was 10.8 +/- 4.6 mV (mean +/- SD) in normal myocardium and was unchanged in hypoperfused segments with maintained glucose metabolism (perfusion/metabolism mismatch), 9.3 +/- 3.4 mV (P = not significant). In contrast, hypoperfused segments with a perfusion/metabolism match and nonviable segments showed significantly lower voltage (6.9 +/- 3.1 mV, P < 0.0001 and 4.1 +/- 1.1 mV, P < 0.0001 vs. normal). In hypoperfused segments, metabolic activity was more closely related to endocardial voltage than was myocardial perfusion (201Tl vs. voltage: r = 0.38, SEE = 3.2, P < 0.001; 18F-FDG PET vs. voltage: r = 0.6, SEE = 2.8, P < 0.0001). CONCLUSION: In hypoperfused myocardium, electrical activity by NOGA mapping is more closely related to PET metabolic activity than to SPECT myocardial perfusion. As NOGA mapping does not differentiate hypoperfused myocardium with enhanced glucose utilization from normal myocardium, results from NOGA mapping need to be correlated with results from perfusion imaging to identify hypoperfused, yet viable, myocardium and to stratify patients for revascularization procedures.

Coronary Artery Disease↗

PubMed2003

Evaluation of myocardial perfusion and left ventricular function six months after percutaneous transmyocardial laser revascularization: comparison of two Ho-YAG laser systems with the same wavelength, but different energy delivery and navigation systems.

BACKGROUND AND OBJECTIVES: Myocardial perfusion and left ventricular function (LVF) were assessed after percutaneous transmyocardial laser revascularization (PTMR) in patients not amenable to conventional revascularization, with a comparison of two laser systems. STUDY DESIGN/MATERIALS AND METHODS: PTMR was performed with an Eclipse laser in 15 patients, and with a Biosense DMR in 10 patients. (201)Thallium scintigraphy, coronary angiography, and ventriculography were performed at baseline and at the 7.5+/-4.3-month follow-up. All patients in the Biosense DMR group and 10 in the Eclipse group underwent NOGA mapping before PTMR and after follow-up. RESULTS: The event-free survival rates were comparable, and the angina scores of all patients improved significantly, but more so in the Biosense DMR group than in the Eclipse group (1.2+/-1.1 vs. 2.3+/-0.9, P < 0.05). Both, the electrical activity assessed by NOGA mapping and the normalized (201)thallium uptake at redistribution improved significantly in the treated segments after Biosense DMR, while the global LVF decreased insignificantly in the Eclipse group. CONCLUSIONS: PTMR resulted in significant improvements in the clinical symptoms, but the electrical activity improved only in the Biosense DMR group, without transforming to a better LVF.

Aged↗

PubMed2003

Arterial compliance: a diagnostic marker for atherosclerotic plaque burden?

BACKGROUND: Previous studies have shown atherogenesis to be related with increased vessel stiffness. Measures of the arterial compliance can be performed noninvasively from pressure pulse contour analysis of arterial waveforms. In this prospective study we aimed to analyze to what extent vessel compliance can reflect the angiographic coronary artery status. METHODS: Large and small arterial elasticity indices (LAEI in milliliters per mm Hg x 10 and SAEI in milliliters per mm Hg x 100) were measured in 151 patients on the radial artery with the PulseWave Sensor HDI device. All patients were classified into diffuse-coronary artery disease (CAD) (defined as stenosis length >15 mm), focal-CAD (defined as stenosis length between 1 and 15 mm), or no-CAD. RESULTS: We found both LAEI and SAEI to be reduced in the diabetic group (LAEI: 11.2 +/- 2.9 v 13.4 +/- 4.5, P =.006; SAEI: 3.7 +/- 1.6 v 4.7 +/- 2.4, P =.01). Inverse association was seen between age and LAEI (r = -0.41; P <.001) and SAEI (r = -0.38; P <.001). No-CAD was found in 31 patients, focal-CAD in 64 patients, and diffuse-CAD in 56 patients. Mean LAEI were 13.8 +/- 3.5, 13.7 +/- 4.7, and 11.3 +/- 3.5 in the groups no-CAD, focal-CAD, and diffuse-CAD, respectively (P =.004), (no-CAD versus diffuse-CAD: P =.04; focal-CAD versus diffuse-CAD: P =.009). Respective SAEI values were 5.6 +/- 2.5, 5.0 +/- 2.1, and 3.1 +/- 1.6 (P <.001), (no-CAD versus diffuse-CAD: P <.001; focal-CAD versus diffuse-CAD: P <.001). Multivariate analysis revealed SAEI (P <.001), hypercholesterolemia (P =.005), systolic blood pressure (BP) (P <.001), mean arterial BP (P <.001), pulse pressure (P =.003), and male gender (P =.001) to be diagnostic markers of the type of vessel disease. CONCLUSIONS: Compliance measurements may be used for identification of patients with diffuse atherosclerotic processes of the coronary arteries.

Age Factors↗

PubMed2003

Serial intravascular ultrasonographic measurements after implantation of biodegradable polymer-coated stents in porcine coronary arteries.

BACKGROUND: Biodegradable stent coatings provide a potential for local drug delivery at the time of vascular injury, while possible tissue toxicity is avoided through constant degradation, leaving behind a bare metal stent. DESIGN: Serial three-dimensional (3D) intravascular ultrasonographic results on bare Megaflex stents and biodegradable polymer-coated Megaflex stents (Hyper stents) (Eurocor, Bonn, Germany) were compared 1 and 4 weeks after intracoronary implantation in pigs. METHODS: Under general anaesthesia, the left anterior descending and circumflex coronary arteries of domestic pigs were stented with Megaflex and Hyper stents, using right femoral artery access. Control coronary angiography and intravascular ultrasonography (IVUS) were performed 1 and 4 weeks after stent implantation using left femoral artery access and right carotid artery access. After recording of angiographic and IVUS data, the pigs were allowed to recover. RESULTS: The 1- and 4-week IVUS follow-ups revealed less neointima formation with Hyper stents than with Megaflex stents: 1-week intimal volume, 11.8+/-0.93 compared with 15.02+/-4.18 mm3, P=0.065; intimal area, 0.81+/-0.06 compared with 1.1+/-0.16 mm2, P =0.003; maximal intimal thickness, 0.12+/-0.01 compared with 0.14+/-0.02 mm, P =0.049; 4-week intimal volume, 12.4+/-1.77 compared with 27.32+/-12.79 mm3, P =0.016; intimal area, 0.82+/-0.12 compared with 1.95+/-0.65 mm2, P=0.003; and maximal intimal thickness, 0.13+/-0.04 compared with 0.30+/-0.10 mm, P=0.003. CONCLUSIONS: Implantation of biodegradable polymer-coated (Hyper) stents results in significantly less neointima formation 1 and 4 weeks after intracoronary implantation than with bare Megaflex stents. Taking advantage of the good collateralization of femoral and carotid arteries of pigs, the use of different arterial accesses allows serial angiographic and 3D IVUS measurements on neointimal development without sacrificing the animals.

Animals↗

PubMed2003

Effects of radial stretch on target lesion revascularization after percutaneous coronary intervention: an intravascular ultrasound study.

OBJECTIVE: To analyze possible associations between radial stretch during coronary angioplasty and the incidence of target lesion revascularization (TLR). PATIENTS AND METHODS: Intravascular ultrasound images were obtained before and after revascularization in 182 native coronary lesions. The quantitative intravascular ultrasound parameters (external elastic membrane cross-sectional area [EEM-A], lumen areas [LA], plaque area [PA], calculated as EEM-A-LA, and changes between pre- and postinterventional LA [DLA], EEM-A [DEEM-A] and PA [DPA]) were correlated with the incidence of TLR. RESULTS: TLR was performed in 60 (33%) patients, while 122 (67%) patients remained event free. Postinterventional PA remained significantly larger in the TLR group than in the event-free group (9.2 +/- 3.3 mm2 versus 7.9 +/- 3.3 mm2; P=0.02). The radial stretch during intervention, expressed as DEEM-A, and the balloon to artery ratio was significantly larger in the TLR group (DEEM-A: 1.9 +/- 2.1 mm2 versus 1.3 +/- 2.0 mm2; P=0.03; balloon to artery ratio: 1.3 +/- 0.2 versus 1.0 +/- 0.5; P=0.04). Multivariate analysis revealed DEEM-A (P=0.01), DPA (P=0.03), diabetes (P=0.001, odds ratio 5.2, 95% CI 4.9 to 6.5) and adaptive remodelling (P<0.001, odds ratio 4.1, 95% CI 3.5 to 6.4) as independent predictors for TLR. CONCLUSION: Whereas patients in whom lumen gain is achieved primarily by plaque reduction with less wall stretch tend to remain event free, patients with significant radial stretch (ie, less reduction of the PA, but a radial outward shift of the plaque mass) experience a higher incidence of TLR.

Aged↗

PubMed2003

Inhibition of interleukin-1beta convertase is associated with decrease of neointimal hyperplasia after coronary artery stenting in pigs.

Inhibition of IL-1beta convertase has been shown to decrease inflammation and apoptosis, which are features of the neointimal development after vascular interventions. The aim of our study was to reduce neointimal proliferation after stenting of the porcine coronary artery, using the irreversible IL-1beta convertase and caspase-1 inhibitor acetyl-tyrosinyl-valyl-alanyl-aspartyl-chloromethyl-ketone (Ac-YVAD-cmk). Before coronary stent implantation, 8 pigs received an intracoronary infusion of 50 mg Ac-YVAD-cmk into the left coronary artery (group 1, n = 8), while 8 animals served as untreated controls (group 2). After 4 weeks, coronary angiography and intracoronary ultrasound (IVUS) with 3D measurements were performed. IVUS revealed a smaller in-stent intimal volume (27.3 +/- 11.6 vs. 75.8 +/- 18.4 mm3, p < 0.005) and a decreased maximal percentage area stenosis (36.1 +/- 8.5 vs. 69.0 +/- 8.2%, p < 0.001) in group 1 vs. group 2. A smaller maximal neointimal thickness (0.63 +/- 0.28 vs. 1.75 +/- 0.94 mm, p < 0.005) and a decreased maximal neointimal area (2.14 +/- 1.29 vs. 5.03 +/- 1.92 mm2, p < 0.005), assessed by computerized planimetry, were found in group 1 vs. group 2. Lower apoptotic indices of the neointimal cells were observed in the treated animals (3.0 vs. 13.4% of total intimal cells, p < 0.05). The coronary arterial tissue IL-1beta level was significantly decreased in the animals treated with Ac-YVAD-cmk (0.254 +/- 0.162 vs. 0.463 +/- 0.307 pg/mg protein, p < 0.05), and exhibited a positive linear correlation (r = 0.581, p = 0.013) with the in-stent plaque volume. In conclusion, intracoronary administration of Ac-YVAD-cmk before coronary artery stenting results in significantly decreased neointimal hyperplasia due to the inhibition of local IL-1beta production and decreased neointimal apoptosis.

Amino Acid Chloromethyl Ketones↗

PubMed2002

Plasma levels of IL-6 correlate with hemodynamic abnormalities in acute pancreatitis in rabbits.

OBJECTIVE: To examine the relationship between plasma cytokine levels and cardiac and hemodynamic function. DESIGN: Measurement of cytokines and the systolic (left ventricular dimensions, heart rate, and cardiac output) and diastolic (early and late transmitral peak flow velocity: E and A-waves and their ratio) functions of the left ventricle (assessed by echocardiography) in rabbits. SETTING AND INTERVENTIONS: Laboratory and echocardiographic analyses were performed at baseline and at 1, 3, 6, 12, and 24 h after acute necrotizing pancreatitis induction (Group ANP), in rabbits after somatostatin pretreatment (Group S-ANP) and in sham-operated controls (Group C). MEASUREMENTS AND RESULTS: Left ventricular dilatation occurred at 6 h and cardiac output was increased 3 h after induction of acute necrotizing pancreatitis. Somatostatin pretreatment mitigated the left ventricular enlargement and filling abnormalities. Plasma level of IL-6 was increased significantly 3 h after pancreatitis induction, but to a lesser extent in Group S-ANP, while somatostatin prevented TNFalpha release (IL-6: Group ANP: 0, 0, 518+/-139, 956+/-125, 373+/-48, and 122+/-37 pg/ml; Group S-ANP: 0, 0, 191+/-68, 261+/-49, 23+/-13, and 0 pg/ml; TNFalpha: Group ANP: 88+/-42, 371+/-40, 2963+/-291, 276+/-30, 197+/-106, and 23+/-14 U/l; Group S-ANP: 91+/-34, 41+/-25, 68+/-42, 25+/-9, 0, and 0 U/ml). The increase in plasma level of IL-6 correlated significantly with left ventricular end-diastolic diameter and volume, cardiac output, and diastolic dysfunction. CONCLUSIONS: Plasma levels of IL-6, but not TNFalpha correlate with cardiac output and left ventricular filling characteristics in acute pancreatitis. Somatostatin pretreatment improves the cardiac and hemodynamic changes, probably through the decrease in cytokine release.

Animals↗

PubMed2002

Geographical miss during intracoronary irradiation: impact on restenosis and determination of required safety margin length.

OBJECTIVE: The goal of this study was to evaluate the incidence and effects of underdosage of injured segments during intracoronary irradiation and to define the minimal length of safety margin required to avoid mismatched source placement. BACKGROUND: Underdosage of injured segments due to misplacement of active source has been suggested as the underlying mechanism for the occurrence of edge restenosis. METHODS: Baseline angiograms of 112 vessels in 109 patients with in-stent restenosis undergoing coronary reintervention followed by intracoronary irradiation ((192)Ir: Checkmate, Cordis, Miami, Florida; (32)P: Gallileo, Guidant, Houston, Texas; (90)Sr/Y: Beta-Cath, Novoste, Norcross, Georgia) were analyzed. The distances between the outermost injury and outermost end of "reference isodose length" (RIL), defined as a segment with >/=90% of reference dose at 1 mm vessel wall depth, were measured. "Safety margin" was defined as the distance between the outermost injury and outermost end of the RIL, "geographical miss" (GM) as a complete injured segment not being covered by the RIL, and "restenosis" as the percent diameter stenosis >50%. RESULTS: Baseline angiographic analysis was performed for 224 edges in 112 vessels. Geographical miss was found in 46 (20.6%) edges. The incidence of target lesion restenosis within the 78 vessels with available follow-up was 43.3% for patients with GM versus 14.9% for patients with no GM (p = 0.005). Analysis of various injured segments exposed highest restenosis rates in injured segments with negligible irradiation (27.8%) in comparison with injured segments with dose fall-off (16.7%) or injured segments with full-dose irradiation (7.7%) (p = 0.006). Receiver operating curve analysis revealed a safety margin of 10 mm required per vessel (i.e., 5-mm safety margin/edge) to achieve 95% specificity of GM. CONCLUSIONS: Geographical miss is associated with a higher incidence of restenosis at the corresponding edges. Restenosis was more pronounced in injured segments with negligible irradiation than in injured segments at the dose fall-off zones. We recommend a safety margin of 10 mm per vessel to minimize GM.

Beta Particles↗

PubMed2002

Intracoronary thrombectomy with the X-sizer catheter system improves epicardial flow and accelerates ST-segment resolution in patients with acute coronary syndrome: a prospective, randomized, controlled study.

BACKGROUND: In patients with acute coronary syndrome (ACS), percutaneous coronary intervention (PCI) may cause thrombus dislodgment followed by reduced flow and impaired microcirculatory function. We prospectively compared conventional PCI to a strategy of additional pretreatment using the X-sizer thrombectomy system. METHODS AND RESULTS: Sixty-six patients (51 [77%] men; 54.9+/-9.9 years) with ACS (49 with ST-elevation infarction [STEMI]) and suspected intracoronary thrombus were randomized 1:1 to pretreatment with X-sizer and conventional PCI alone. Various aspects of epicardial flow and microvascular function were studied. Baseline data were similar in both groups. Postprocedural TIMI 3 flow was obtained in 90% of X-sizer-treated patients and in 84% of controls (NS); however, corrected TIMI frame count was lower in X-sizer- treated patients (18.3+/-10.2 versus 24.7+/-14.1; P<0.05). No significant group differences were observed in final coronary flow reserve, myocardial blush grade, and myocardial dye intensity. In STEMI, the sum of ST elevation was significantly lower in X-sizer-treated patients immediately after (2.78+/-3.05 versus 6.15+/-6.32 mm; P<0.03) and 6 hours after (2.17+/-2.31 versus 4.14+/-3.7 mm; P<0.05) intervention. ST-segment resolution >50% was observed in 83% of X-sizer-treated patients and in 52% of controls (P<0.03). Multivariate analysis identified X-sizer treatment as the single independent predictor of ST-segment resolution >50% (OR 4.35; 95% CI, 1.13 to 16.9; P<0.04). Major adverse cardiac events after 30 days occurred in 2 patients in each group. CONCLUSIONS: In ACS with suspected thrombus, pretreatment with the X-sizer catheter system improves epicardial flow and accelerates ST-segment resolution compared with conventional PCI alone.

Acute Disease↗

PubMed2002

Vascular morphometric changes after radioactive stent implantation: a dose-response analysis.

OBJECTIVES: The goal of this study was to evaluate the dose-dependency of morphometric changes in the coronary arterial wall after radioactive stenting. BACKGROUND: Radioactive stents have been found to reduce intrastent intimal hyperplasia (IIH) but lead to a characteristic type of restenosis occurring predominantly at the stent edges. METHODS: Fifteen patients underwent intravascular ultrasound (IVUS) examination after implantation of a P-32 radioactive stent and at the six-month follow-up. The post-stent IVUS measurements on seven predefined locations of each lesion were subjected to a computer algorithm for the development of dose-volume histograms (DVH). Thus, we derived the radiation doses delivered to at least 10% and 90% of the adventitia (DV10, DV90). The IIH and vascular remodeling at follow-up were correlated with the doses in each segment. RESULTS: The IIH was most pronounced at the stent edges and lowest in the stent-body, whereas we detected a significant expansive remodeling within the stent body. The delivered doses correlated with a decreased IIH (r = 0.52, p < 0.001 for DV10 and r = 0.62, p < 0.001 for DV90) and with expansive remodeling (r = 0.48, p = 0.009 for DV10 and r = 0.50, p = 0.006 for DV90). A DV10 >90 Gy or a DV90 >15 Gy reduced IIH and induced expansive remodeling. Plaque growth was not reduced by radioactive stents. CONCLUSIONS: The DVH analysis reveals a dose-dependent increase of external elastic lamina area behind radioactive stents, whereas plaque growth is not reduced but inverted into an outward direction from the stent. A DV10 >90 Gy or a DV90 >15 Gy results in a beneficial long-term outcome after radioactive stenting.

Arteries↗

PubMed2002

Short- and long-term results of emergency and elective percutaneous interventions on left main coronary artery stenoses.

In this prospective study, we analyzed the short- and long-term outcomes of percutaneous interventions on significant left main coronary artery (LM) stenoses. Between January 1998 and June 2000, 18 patients underwent emergency interventions on unprotected LM stenoses (group 1), while 15 patients had elective interventions on protected LM stenoses (group 2). Despite a procedural success of 88.9% in group 1, event-free in-hospital and mortality rates were 50.0% and 38.9%. After 6.4 +/- 4.4 months of follow-up, late event-free survival and mortality rates were 33.3% and 38.9%. In group 2, procedural success was 100%, with 100% event-free in-hospital survival; late event-free survival and mortality rates were 93.3% and 0% after 6.7 +/- 4.1 months of follow-up. Emergency interventions on LM stenoses remain a procedure with high acute and mid-term mortality. In spite of the high rate of major adverse cardiac events, an acceptable long-term survival can be achieved.

Aged↗

PubMed2002

Determination and application of the reference isodose length (RIL) for commercial endovascular brachytherapy devices.

BACKGROUND AND PURPOSE: During the last years endovascular brachytherapy has been established as a new field in radiotherapy. In a recent recommendation of the EndoVAscular, Groupe Européen de Curiethérapie, European Society for Therapeutic Radiation Oncology, Working Group the reference isodose length (RIL) has been introduced as a central parameter for treatment planning. It is defined as the vessel length at the reference depth enclosed by the 90% isodose. The dose is normalized to 100% at the reference depth (i.e. lumen radius plus 1 mm into the vessel wall) at the central plane. In order to avoid a geographic miss the clinical target length has to be encompassed by the RIL. MATERIAL AND METHODS: RILs are determined by Monte Carlo calculations and GafChromic film dosimetry for three endovascular brachytherapy devices currently in clinical use (192Ir seed ribbon, 32P wire source, 90Sr seed train). For all measurements, phantoms and devices the sensitive layer of GafChromic film is located in a plane at 2+/-0.1 mm parallel to the axis of the source delivery catheter. The EGSnrc code system is applied to calculate the dose profile at 2 and 3 mm distance from the source axis. RESULTS: For the ten seed 192Ir source calculated RIL at 2 mm radial distance is 30.2 mm whereas the measured RIL is 33.5 mm. In case of a 20 mm 32P wire source with two steps the calculated RIL of 36.6 mm shows excellent agreement compared with the measured value of 36.2 mm. The calculated RIL of a 40 mm 90Sr seed train was 35.8 mm compared to a measured value of 34.8 mm. CONCLUSION: As a compromise between calculated and measured RIL values at 2 and 3 mm radial distances we propose to use a RIL of 30 mm for the 192Ir ten seed ribbon, 36 mm for the32P wire source with two steps and 35 mm for the 40 mm 90Sr seed train. These parameter values can be used to define the maximum intervention length for endovascular sources.

Beta Particles↗

PubMed2002

Predictors of survival in unselected patients with acute myocardial infarction requiring continuous catecholamine support.

BACKGROUND: Several predictors of survival have been described in selected subgroups of patients suffering from acute myocardial infarction. However, data on unselected patients with acute myocardial infarction and cardiogenic shock, including patients with out-of hospital cardiac arrest, are missing. We aimed to assess predictors of survival for an unselected cohort of patients representative of clinical practice who experienced acute myocardial infarction and required continuous catecholamine support for circulatory failure. METHODS: The study was performed at a 2000 bed university hospital. All consecutive patients admitted to our emergency department with acute myocardial infarction were prospectively enrolled in a clinical trial from 1993 to 2000. DESIGN: A retrospective cohort study was performed on patients with myocardial infarction requiring catecholamine support within the first 24 h. Primary endpoint was in-hospital mortality. RESULTS: The analysis was carried out on 262 patients, 189 men (72%), median age 65 years (IQR 53-73). Out-of-hospital cardiac arrest was reported in 47% (122/262). In-hospital mortality was 53% (138/262). Survivors as compared to non-survivors exhibited significant differences with respect to age (60 vs. 68 years, P<0.0001), systolic and diastolic blood pressure on admission (110 vs. 102 mmHg, P=0.01 and 64 vs. 58 mmHg, P=0.006, respectively), initial blood serum lactate (6.8 vs. 8.3, P=0.01), peak CKMB level (93 vs. 138 U/l, P=0.005), use of adrenaline (epinephrine) (38 vs. 68%, P<0.0001) and any attempt of revascularisation (76 vs. 63%, P=0.03). In a multivariate model younger age [OR 1.06 (CI 1.03-1.10), P<0.001], no use of adrenaline [OR 2.63 (CI 1.35-5.26) P=0.005] and lower peak CKMB [OR 1.01 (CI 1.01-1.01), P<0.0001] were independently associated with in-hospital survival. CONCLUSION: In unselected patients including CPR survivors with acute myocardial infarction requiring continuous catecholamine support, younger age, the absence of continuous adrenaline administration and a lower peak CKMB were independently associated with increased in-hospital survival.

Aged↗

PubMed2002

Case-based distance measurements for the selection of controls in case-matched studies: application in coronary interventions.

In case-based studies, controls are retrospectively assigned to patients in order to permit a statistical evaluation of the study results through a comparison of the main outcome measures for the patient and retrieved control groups. Inappropriate selection of the controls by using false retrieval parameters or a false algorithm might lead to an incorrect data analysis and a false interpretation of the results. The main hypothesis of the presented study was that, if the matching baseline parameters were at least nearly perfectly selected, then the outcomes of the matched pairs should be similar, or no significant differences in study outcome should be observed between the patients and the matched controls. In the present study, the case-based domain was created from 1566 patients who had undergone intracoronary stent implantation. Uni- and multivariate logistic regression analysis determined nine significant predictors (matching variables) for the occurrence of major adverse cardiac events. An additional 425 consecutive patients undergoing intracoronary stent implantation were then matched with all the potential controls from the database by calculating the individual distance between the patient and the matched control on the basis of the elaborated retrieval algorithm. To test the matching hypothesis, different distance measurements, and an altered outcome and retrieval process were examined. With "flexible" distance measurements, the mean distance between the patients and the first matched controls was 1.31. The major adverse cardiac events were compared in the patient and matched control groups. The best sensitivity and specificity values of the matching system could be achieved in matched pairs with the distance < or =3.00 (95.1% of all patients). On the further stepwise exclusion of the matched pairs exhibiting a distance greater than 2 and 1, then the number of "matchable" controls and the specificity of our matching concept decreased considerably. When the short- or mid-term outcome was compared by using the long-term follow-up matching parameters, no correlation could be found between the treated subjects and controls, indicating that for the other study, main measures of other appropriate parameters must be selected, and demonstrating the importance of the outcome-oriented selection of the retrieval parameters. Furthermore, the outcome measures of the patients and randomly (non-systematically) selected controls did not correlate, revealing the impossibility of drawing correct study conclusions from a non-matched, randomly assigned pairs. In conclusion, the sensitivity and specificity of the matching program, and the study conclusions depend on the appropriately predefined matching parameters and retrieval algorithm.

Algorithms↗

PubMed2002

Intimal hyperplasia and coronary flow reserve after heart transplantation: association with big endothelin-1.

BACKGROUND: Endothelin, a peptide with strong vasoconstrictive and mitogenic properties, has been found to increase after cardiac transplantation. We therefore assessed the association between its precursor peptide, big endothelin-1, and intimal hyperplasia and coronary flow reserve after heart transplantation. METHODS: Thirty-five patients without hemodynamically significant coronary artery disease after heart transplantation were investigated: Average peak flow velocity in the left anterior descending artery (LAD) was assessed by intracoronary Doppler at baseline as well as after injection of adenosine; coronary flow reserve was calculated as a ratio of both and was corrected for patient age and baseline average peak flow velocity. Lumen, intima + media and total vessel area were measured by intracoronary ultrasound. The plasma concentration of big endothelin-1 in venous blood was determined by radioimmunoassay. RESULTS: Patients with elevated big endothelin-1 levels (>2 fmol/ml) tended to have a decreased corrected coronary flow reserve (2.60 +/- 0.9 vs 3.21 +/- 1.0, p = 0.078). They also had a significantly larger intima + media area (5.82 +/- 2.9 vs 2.37 +/- 2.9 mm(2), p = 0.004) and total vessel area (18.36 +/- 5.8 vs 12.81 +/- 4.8 mm(2), p = 0.012) than those with normal plasma concentrations. CONCLUSIONS: Our study suggests an association between elevated big endothelin-1 plasma levels and the development of intimal hyperplasia and reduction of coronary flow reserve after cardiac transplantation.

Adult↗