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Biomedical subjects

R Uebis

Publications and source records attributed to R Uebis.

At least 37 records · Page 2Linked to original sources
PubMed1991

Morphologic change in coronary artery stenosis with the Medtronic Wiktor stent: initial results from the core laboratory for quantitative angiography.

The purpose of this study was to assess the early changes in stenosis geometry after implantation of the Medtronic Wiktor stent in human coronary arteries. Morphologic changes were evaluated by quantitative coronary angiography using automated edge detection. The hemodynamic significance of the morphologic changes were assessed by the calculation of the theoretical pressure drop across the dilated and stented stenosis derived from the Poiseuile and turbulent resistances assuming a coronary blood flow of either 0.5, 1, or 3 ml/sec. Fifty patients were studied before and immediately after stent implantation. The stented coronary artery was the left anterior descending artery in 26 patients, the circumflex artery in eight patients, and the right coronary artery in 16 patients. Stent implantation resulted in an additional increase in the minimal luminal cross-sectional area and minimal luminal diameter of the dilated vessel without changing the curvature of the stenosis. Furthermore, there was a significant reduction of the "plaque area." This was associated with a normalization of the calculated resistances to flow and pressure drop across the stenosis. To a minimal extent, recoil (0.1 +/- 0.36 mm) was observed after stent implantation.

Adult↗
PubMed1991

Successful treatment of massive pulmonary embolism by combined mechanical and thrombolytic therapy.

In two patients with massive pulmonary embolism and cardiogenic shock requiring mechanical ventilation and prolonged external cardiac massage, occluded pulmonary arteries were recanalized by primary mechanical fragmentation of thrombi using a percutaneously inserted catheter followed by fibrinolytic therapy. The hemodynamic and respiratory parameters rapidly and greatly improved. Pulmonary angiography before discharge revealed normal results in both patients. No central neurological abnormalities were detected. It is concluded that patients with cardiogenic shock due to massive pulmonary embolism may benefit from immediate mechanical thrombus fragmentation followed by fibrinolysis when thrombolysis or surgical embolectomy are strictly contraindicated or not available.

Adult↗
PubMed1991

[Long-term results of elective percutaneous transluminal coronary angioplasty. A clinico-angiography study of 289 consecutive patients].

289 consecutive patients (255 male, 34 female, 50 +/- 6 years) had an elective single-vessel-PTCA between October 1978 and March 1983. A clinical long-term follow-up was obtained after 4.7 (3-10) years. The PTCA success-rate was 73% with a non steerable balloon catheter being used in 95% of the cases. For 271/289 patients with follow-up (94%), the 56-month-survival rate was 96%, the incidence of non-fatal myocardial infarctions 11%, and the need for a second intervention (PTCA and/or bypass surgery) was 39%. The most favorable long-term outcome was observed in patients without need of a second intervention (97% survival, 7% non-fatal myocardial infarction, 83% without cardiac complaints during everyday life), and in patients with elective bypass surgery after an unsuccessful PTCA (100% survival, 5% myocardial infarction). 32/138 (23%) of patients without a second intervention during follow-up underwent an angiographic control after an average of 4.7 years. In comparison with the first follow-up angiogram 6 months after PTCA, the mean residual stenosis at the PTCA-site showed a slight decrease. It is concluded that PTCA offers good clinical and angio-graphic long-term results in single-vessel disease, with an excellent prognosis of patients without need for a second intervention.

Angioplasty, Balloon, Coronary↗
PubMed1991

MRI measurements of left ventricular systolic wall thickening compared to regional myocardial perfusion as determined by 201Tl SPECT in patients with coronary artery disease.

Magnetic resonance imaging (MRI) of the left ventricle (LV) is an excellent method of measuring systolic wall thickening (SWT). The aim of the present study was (a) to describe a new approach for measurement of SWT and (b) to define the relationship between SWT and regional myocardial perfusion as determined by 201Tl SPECT. 79 patients -51 with and 28 without history of earlier myocardial infarction - underwent SPECT and, within the next two weeks. MRI. End-diastolic and end-systolic spin echo images were obtained by a reduced permutation technique. For MRI measurements, only long-axis sections through the LV in the equatorial plane were used. Slice orientation was selected according to the findings of SPECT, imaging the infarcted wall segment by single or double angulation. At 7 equidistant points around the LV wall SWT was measured and compared with the corresponding regional myocardial uptake values from SPECT in percent of maximal perfusion. Wall thickness of the anterior wall was normal. Because the majority of myocardial infarctions were posterior-inferior (55%), thickness of the posterior wall was markedly decreased. A close relationship of perfusion to SWT was found. Higher perfusion areas (greater than 50% of maximal TI uptake) corresponded with normal SWT (greater than 3.0 mm), a marked decrease of SWT (less than 1 mm) was found in areas with perfusion deficits (less than 40%). Thus, a 201TI uptake value at rest of 41-50% of the respective myocardial maximum acts as a threshold by discriminating normal from severely reduced SWT.

Adult↗
PubMed1990

Methoxyisobutylisonitrile (MIBI) Tc 99m SPECT to establish a correlate to coronary flow reserve, the perfusion reserve, from global and regional myocardial uptake after exercise and rest.

With 99mTc-MIBI SPECT and a 4 h exercise (E: 150 MBq iv) and rest (R; 800 MBq iv) protocol, global and regional left ventricular (LV) myocardial uptake was determined in 70 patients with angiographically confirmed coronary heart disease (CHD) and in 10 controls. The aim was to establish an E/R ratio as a correlate to coronary vascular reserve, representing perfusion reserve (PR). E/R ratios, obtained from total LV myocardium or from normal or impaired regions, were greater than 1.19 under all conditions, indicating the presence of higher flow during exercise than at rest (even in areas of low flow). Global PR separated (P less than 0.01) controls (1.63 +/- 0.21; mean +/- SD) from severely diseased patients (1.29 +/- 0.14 in 2- or 3-vessel disease) only. Improved differential diagnosis was gained from calibrating the regional E/R ratio to regional differences (E minus R) of uptake. For the left ventricle regional PRs (RPR) for 25 ROIs of the target, framing the myocardium, were determined. RPR at the regional maximum of 99mTc-MIBI uptake was similar in both controls (1.66) and patients (1.63), indicating a high probability of meeting some areas with functionally normal perfusion in patients with CHD. RPR allowed sufficient separation (P less than 0.025) concerning the degree of coronary artery stenosis (RPR in occlusion, 0.26; stenosis greater than 75%, 0.39; less than 75%, 0.56). In controls, the overall value for RPR was 1.14 +/- 0.28 (P less than 0.001). LV global PR and RPR were useful in separating patients with CHD vs controls and in classifying the severity of vascular stenosis.

Adult↗
PubMed1990

99Tcm-methoxy-isobutyl-isonitrile SPECT to evaluate a perfusion index from regional myocardial uptake after exercise and at rest. Results of a four hour protocol in patients with coronary heart disease and in controls.

In 70 patients with angiographically confirmed coronary heart disease and in 10 controls, a 4 h exercise (E) (injection of 150 MBq 99Tcm-MIBI) rest (R) (800 MBq) protocol was employed. Of these, 10 patients with 21 myocardial defects after E received a third injection 24 h after. SPECT was used to image myocardial distribution, and visual findings separated three patterns of perfusion defects after E v. R (reversible [REV], partial reversible (PREV), irreversible (IRR)). Relative regional uptake was obtained from a target-like (33 ROIs) evaluation of short-axis cuts, establishing a perfusion index (PI) by relating the defect uptake to individual maximum uptake (100%) after exercise (PIE), at rest (PIR) and the respective differences Delta PI (PIR-PIE, i.e. filling in by the second 99Tcm-MIBI injection). Visually, the sensitivity was 86% in patients or 69% in involved vessels (stenoses of greater than 33%). Vascular supply areas revealed minimal PIE values of 74.7 +/- 10.6% (control), 62.4 +/- 9.2% (REV), 46.1 +/- 7.7% (PREV) and 33.5 +/- 9.9% (IRR) (p less than 0.01). Delta PI was +13.2% or +10.1% in REV or PREV (n.s.) and +2.1% in IRR (p less than 0.01) or -0.2% in controls. PIE values did not correlate to the degree of stenosis. In areas with old myocardial infarction, the same sequence of significant decrease of PIE with reversibility occurred, independent of the patency of the supplying vessel. 33 of 35 IRR defects (94.3%) revealed PIE of less than 45%, thus predicting IRR already after the E examination. PIR values from the 4 h protocol correlated to PIR values 24 h thereafter with r = 0.94 (n = 21). 99Tcm-MIBI may be employed in a short one day E-R protocol in clinical routine. Evaluation of PI seems to be a promising tool to quantify visual defects aimed at describing the perfusional state of the terminal vascular supply area.

Adult↗
PubMed1989

[A heart rate adaptable "physiologic" pacemaker. Is the effort worthwhile?].

The dual-chamber pacemaker provides an approximately physiologic cardiac action in patient with 3rd degree AV-block and preserved sinoatrial function. Newly developed so-called rate-responsive systems are now available. Initial clinical experience has been reported with pacemakers controlled via respiration rate, activity, central venous blood temperature, or intracardially measured QT-interval. The sensitivity and specificity of rate regulation like the effort of implantation and setting is not completely satisfactory and adequate until now. At the present time, such systems are being implanted mainly according to individual indications. Before a general use can be recommended, several problems still remain to be solved, in particular the question as to what therapeutic advantage is to be expected with respect to the underlying disease, arrhythmia and patient group.

Bradycardia↗
PubMed1989

Evolution of left ventricular function after intracoronary thrombolysis for acute myocardial infarction.

The temporal evolution of left ventricular (LV) function after intracoronary streptokinase therapy for acute myocardial infarction (AMI) was assessed from the data of 264 patients who had complete occlusion of either the left anterior descending or the right coronary artery before treatment. Angiography was performed immediately, and at 3 days and 6 months after AMI in 91%, 71% and 47% of the study group, respectively. Wall motion was measured by the centerline method. In patients with sustained reperfusion, the ejection fraction decreased at 3 days (delta = -2.0 +/- 9.9%, n = 134, p = 0.02) and recovered later (from 54 +/- 12% acutely to 57 +/- 12% at 6 months, n = 82, p less than 0.05). These changes in global function were associated with a marked regression in hyperkinesis in the noninfarcted wall by 3 days, and delayed recovery of wall motion in the infarct region (delta = 0.2 +/- 0.9 at 3 days, p = 0.055; 1.0 +/- 1.2 at 6 months, p less than 0.001). Patients without reperfusion or with reocclusion had a more severe decrease in ejection fraction at 3 days, and little or no subsequent functional recovery. The length of the hypokinetic segment increased significantly by 3 days but subsequently diminished to slightly less than the acute value. It is concluded that full recovery of ischemically impaired myocardium takes greater than 3 days, but compensatory hyperkinesis regresses earlier so that global LV function deteriorates by the third day. Variability or deterioration of LV function early after AMI need not be due to infarct extension; it can reflect regression of hyperkinesis in the noninfarcted region.

Angiography↗
PubMed1989

Controversial aspects of coronary endarterectomy.

Between 1980 and 1987, 635 patients underwent coronary bypass grafting combined with coronary endarterectomy. A total of 728 vessels were endarterectomized and grafted. There were 15 early deaths (2.3%). The mortality rate was higher (7.8%) for multiple-vessel endarterectomy (p less than 0.05). The ratio of MB fraction of creatine kinase to total creatine kinase was greater than or equal to 0.10 in 48% of the cases. The first consecutive 132 survivors were followed for an average of 16 months (range, 4 months to 5 years). No late deaths occurred. Fifty-nine unselected patients underwent postoperative recatheterization at a mean interval of 18 months. An improvement in heart wall contractility could be detected in 13 patients (16.5%) and deterioration in 14 patients (17.7%). A more detailed analysis of wall contractility showed a higher rate of improvement in the posterior wall than in the anterior wall (p greater than 0.05). Furthermore, the better the contractility before operation, the greater the rate of deterioration after operation (p less than 0.05). Despite an average of 55% of all endarterectomized vessels being occluded or severely restenosed, 90% of the patients were clinically improved. A multiparametric analysis revealed that the revascularization of myocardial areas that required endarterectomy had no significant influence with respect to clinical improvement. Endarterectomy should be limited, whenever possible, to myocardial areas with already impaired contractility. Endarterectomy of multiple branches should be treated with caution because the risk of deterioration is potentiated, with a significantly higher perioperative mortality rate.

Adult↗
PubMed1989

Late results after intracoronary thrombolysis and early bypass grafting for acute myocardial infarction.

Successful thrombolysis for acute myocardial infarction reduces early mortality. For definite correction of the underlying arteriosclerotic lesion, invasive treatment is mandatory. Early bypass grafting has been performed in 70 patients with an ischemic interval of less than 4 hours before reperfusion by thrombolysis. Surgery was undertaken an average of 4.5 days after the streptokinase administration. The hospital mortality rate was 1.4%. At 8 years the actuarial survival rate was 88% and the complication-free survival rate, 84%. At the latest follow-up study, 90% of the patients were in functional class I or II. Because of advanced age, 37% of the survivors have retired and 29% are working. Thirty-four percent did not return to work after the operation. In 24 patients a transmural needle biopsy specimen was taken at operation to study the extent of ischemic damage. Surprisingly, the extent of necrosis did not correlate with the ischemic interval (r = 0.17), whereas enzyme activity and extent of necrosis did correlate (r = 0.76). Late angiography was done in 44 patients (56%). The correlation between ischemic interval and regional wall motion score was weak when the whole group was considered (r = 0.35), but 70% of the patients with an ischemic interval of less than 3 hours had normal or near normal regional wall motion. In patients with prolonged ischemia, distribution between normal function and severe damage was uniform. In patients with ultrastructural and wall motion studies, early necrosis and late left ventricular function correlated fairly well (r = 0.69). We conclude that additional early bypass grafting after successful thrombolysis yields excellent long-term clinical results, especially in patients with an ischemic interval of less than 3 hours.

Age Factors↗
PubMed1988

Early recovery of left ventricular function after thrombolytic therapy for acute myocardial infarction: an important determinant of survival.

Thrombolytic therapy for acute myocardial infarction reduces early mortality, but full recovery of left ventricular function after reperfusion is delayed. Therefore, the relations among reperfusion, survival and the time course of left ventricular functional recovery were examined in 226 patients treated with intracoronary streptokinase; 77% (134 patients) had sustained reperfusion and 31 patients had no reperfusion or had reocclusion by day 3. Wall motion was measured from contrast ventriculograms performed in the acute period and 3 days later in the central and peripheral infarct regions and the noninfarct region by the centerline method in 165 patients. Patients with reperfusion had better survival (p less than 0.05, mean follow-up 4.5 years) and a higher ejection fraction at 3 days (52 +/- 12 versus 46 +/- 10%, p less than 0.02) attributable to a significantly different change in peripheral infarct region function between the acute and 3 day studies (0.1 +/- 1.0 versus -0.3 +/- 0.9 SD, p less than 0.05). These early functional changes were significant in patients with anterior myocardial infarction and showed similar trends in those with inferior myocardial infarction. On Cox regression analysis, function measured at 3 days was more predictive of survival than was function measured acutely (chi square for acute ejection fraction = 11.48 versus 24.59 at 3 days). Although, as previously reported, greater than 45% of total recovery of left ventricular function occurs later, the ejection fraction achieved by day 3 is already predictive of survival. Thus, the mechanism by which successful thrombolytic therapy enhances survival is improvement of regional and global left ventricular function early after acute myocardial infarction.

Coronary Circulation↗
PubMed1988

[Comparative randomized study of the effectiveness of intravenous recombinant tissue-type plasminogen activator and intravenous streptokinase in patients with acute myocardial infarct. Report of the European Cooperative Study Group for Recombinant Tissue-Type Plasminogen Activator].

In a single-blind randomised trial in patients with acute myocardial infarction of less than 6 h duration, the frequency of coronary patency was found to be higher after intravenous administration of recombinant human tissue-type plasminogen activator (rt-PA) than after intravenous streptokinase. 64 patients were allocated to 0.75 mg rt-PA/kg over 90 min, and the infarct-related coronary artery was patent in 70% of 61 assessable coronary angiograms taken 75-90 min after the start of infusion; 65 patients were allocated to 1,500,000 IU streptokinase over 60 min, and the infarct-related vessel was patent in 55% of 62 assessable angiograms. The 95% confidence interval of the difference ranges from +30 to -2% (p = 0.054). Bleeding episodes and other complications were less common in the rt-PA patients than in the streptokinase group. Hospital mortality was identical in the 2 treatment groups. At the end of the rt-PA infusion the circulating fibrinogen level was 61 +/- 35% of the starting value, as measured by a coagulation-rate assay, and 69 +/- 25% as measured by sodium sulphite precipitation. After streptokinase infusion, corresponding fibrinogen levels were 12 +/- 18% and 20 +/- 11%. In the rt-PA group only 4.5% of the fibrinogen was measured as incoagulable fibrinogen degradation products, compared with 30% in the streptokinase group. Activation of the systemic fibrinolytic system was far less pronounced with rt-PA than with streptokinase.

Adult↗
PubMed1988

[Reocclusion following successful thrombolytic therapy in acute myocardial infarct].

Following successful reperfusion of the previously occluded coronary artery in acute myocardial infarction, reocclusion remains an at least partially unsolved problem. The literature reports figures between 10 and 30%. In the present study, 130 out of 543 patients with successful thrombolysis by means of intracoronary streptokinase underwent a follow-up angiography at the 3rd day (106/130, 80%) and/or 6 months (76/130, 59%) after the acute intervention. During the observation period, neither PTCA nor bypass surgery were performed. Reocclusion could be documented in 5.5% of patients at the early stage, and in 25.0% half a year later. In more than 75% of patients, who presented with a reoccluded infarct related artery, clinical evidence of reinfarction had been recorded during the follow-up period.

Coronary Circulation↗
PubMed1987

Effect of continued rt-PA administration on the residual stenosis after initially successful recanalization in acute myocardial infarction--a quantitative coronary angiography study of a randomized trial.

Quantitative angiography was performed in 68 out of 123 patients treated with intravenous rt-PA for acute myocardial infarction. At 90 min angiography, the median minimal cross-sectional area was 1.11 mm2 and the median percentage area stenosis was 80%. A percentage area stenosis greater than 70% was seen in 78% of the patients. Patients with a patient infarct related artery at the first angiogram were randomized to receive subsequent infusions either of rt-PA + heparin or placebo + heparin. There was a persistent trend of improvement in minimal lumen diameter and percentage diameter stenosis of the residual stenosis in the infarct related artery in both treatment groups when re-examined 6-24 hours later and at the time of hospital discharge. A reduction in 'plaque area', the area between the detected and the reference contours of the infarct related segment, was more frequently seen in patients receiving a second infusion of rt-PA than in patients with no prolonged thrombolytic therapy (83% versus 57%, P less than 0.025, chi square).

Cineangiography↗
PubMed1987

Residual coronary stenosis after thrombolysis with rt-PA or streptokinase: acute results and 3 weeks follow-up.

Ninety-one patients with acute myocardial infarction were assigned to intravenous treatment with streptokinase or rt-PA as part of the randomized trial carried out by the European Study Group for Recombinant Tissue-Type Plasminogen Activator (rt-PA). A patent coronary artery was found in 37 of 45 (82%) patients treated with rt-PA and in 27 of 46 (59%) patients treated with streptokinase 75-90 minutes after start of infusion. Patients were subsequently anticoagulated with heparin or dicoumarol up to a repeat angiography 3 weeks after the infarction. Of the 64 patients with successful reperfusion, 3 died and 3 suffered reocclusion of the vessel. Quantitative analysis of the coronary stenosis both immediately after thrombolysis and at 3 weeks follow-up was possible in 33 cases. Residual stenosis (percentage narrowing of diameter) decreased from 74 +/- 14% to 56 +/- 17% (P less than 0.05). No difference was observed between the groups of patients treated with streptokinase (74 +/- 9% to 57 +/- 12%, N = 17) and with rt-PA (74 +/- 17% to 56 +/- 21%, N = 16). Despite the significant regression, a coronary stenosis of more than 50% of the diameter persisted in 82% of the patients three weeks after the infarction.

Cineangiography↗
PubMed1987

Quantitative evaluation of myocardial stress/rest 201TL SPECT: results of a ROI-based method in 108 patients with CHD.

ROI-based polar maps (33 ROIs) were employed to evaluate quantitatively stress/rest myocardial 201Tl SPECT in 108 patients with angiographically proven coronary heart disease (CHD) in comparison with 30 controls. Sensitivity in detecting a CHD with stenoses of greater than 50% of luminal diameter was determined versus normal regional values (+/- 2.5 SD) employing vitality (VI) and wash-out corrected redistribution (RD). The method was evaluated referring to the severity of the disease, to the number of ROIs displaying changes [(a) 1 ROI, (b) greater than 2 ROIs], to validity of VI, RD or a combination thereof, and for specificity. Wash-out values were found to depend on degree of stress individually achieved and thus were not used as a threshold criterion. Sensitivity in supply areas with old myocardial infarctions was 95% (a) and 86% (b), resp. With no infarction, it was 96% (a) and 79% (b), resp. VI in stenosis greater than 75% was more sensitive than RD. However, combined evaluation of VI and RD yielded sensitivities from 91-100% (a) and 77-94% (b), resp. for different main supply areas. In stenosis less than 50% with normal VI, RD was positive in 18-31%. Specificity turned out to be 91% (a) and 97% (b), resp. We conclude that the method presented is reliable to quantify numerically 201Tl kinetics in myocardial SPECT, aimed at detecting and describing CHD.

Adult↗