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W Krebs

Publications and source records attributed to W Krebs.

At least 73 records · Page 4Linked to original sources
PubMed1984

Sensitivity and specificity of two-dimensional echocardiography in detection of impaired left ventricular function.

The purpose of the study was to determine the sensitivity and specificity of two-dimensional echocardiography (2dE) in the detection of impaired left ventricular function, compared with cineventriculography (CVG). Apical two-dimensional echocardiograms were performed in 110 patients undergoing heart catheterization for the evaluation of clinically suspected coronary heart disease (50 patients), valvular heart disease (38 patients) and congestive cardiomyopathy (22 patients). The left ventricle was scanned in the RAO-equivalent view; cineventriculograms were filmed in the 30 degrees RAO projection. Left ventricular volumes at end-diastole (EDV) and end-systole (ESV) were determined using a disc method; stroke volume (SV) and ejection fraction (EF) were calculated. Based on normal values, the sensitivity, specificity, and predictive accuracy were determined for two-dimensional echocardiography. For EDV, the sensitivity was 80%, specificity 88% and (+) predictive accuracy 86%. The left ventricular ejection fraction was 57.8 +/- 17.2% with CVG and 53.8 +/- 15.6% with 2dE in patients with coronary heart disease, 24.9 +/- 10.5% with CVG and 25.2 +/- 11.1% with 2dE in patients with congestive cardiomyopathy, and 61.1 +/- 13.9% with CVG and 54.2 +/- 9.1% with 2dE in patients with valvular heart disease. Sensitivity was 81%, specificity 100%, and (+) predictive accuracy 100%. The study demonstrates that impaired left ventricular function can be detected by 2dE with high sensitivity and specificity. Thus, 2dE seems to be suitable screening method for evaluation of left ventricular function.

Adult↗
PubMed1984

[Determination of the size of the right atrium in patients with pulmonary hypertension using 2-dimensional echocardiography].

Normal values for right atrial area and tricuspid annular diameter and their percentage shortening measured from the two-dimensional echocardiographic four-chamber view are now available. In this study right atrial size of patients with pulmonary hypertension is evaluated and the results compared with the M-mode findings of the right ventricle in order to detect pulmonary hypertension. Hemodynamics and echocardiograms of 60 patients (mean age 57 +/- 10 years) with mitral stenosis III-IV NYHA and concomitant pulmonary hypertension were examined. 20 patients in group I with atrial fibrillation had additional functional tricuspid incompetence. Unlike the 20 patients in group II, who had atrial fibrillation, the remaining 20 in group III were still in sinus rhythm. The mean pulmonary artery pressure was 44.1 +/- 9.3 mmHg in group I, in group II 33.9 +/- 6.3 mmHg (grp. I vs. grp. II p less than 0.001) and in group III 33.2 +/- 7.1 mmHg (grp. II vs. grp. III ns). The end-systolic index of the right atrial area in group I was 19.6 +/- 5.7 cm2/m2 and thus significantly greater than in group II with 10.6 +/- 2.3 cm2/m2 (p less than 0.001) and in group III with 9.1 +/- 2.5 cm2/m2 (p less than 0.001). The maximal diameter of the tricuspid annulus measured 24.6 +/- 5.5 mm/m2 in group I, 18.9 +/- 3.5 mm/m2 in group II (grp. I vs. grp. II p less than 0.001) and 20.2 +/- 2.2 mm/m2 in group II (grp. I vs. grp. II p less than 0.001) and 20.2 +/- 2.2 mm/m2 in group III.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1984

[Determination of the size of the right atrium using two-dimensional echocardiography].

Echocardiographical and functional parameters of the right ventricle have been established. In addition, to improve the analysis of right heart dynamics, normal values for right atrial dimensions and the tricuspid valve anulus diameter are required. We therefore examined 30 normal adult subjects, 15 males (aged 31 +/- 10 years, mean +/- SD) and 15 females (aged 28 +/- 8 years) using two-dimensional echocardiography in the apical 4-chamber view. The contour of the right atrium was delineated with a light pen, and the end-diastolic and end-systolic areas were calculated using a computerized integration method; the percentage area shortening fraction was determined as end-systolic area - end-diastolic area/end-systolic area. The diameter of the tricuspid anulus was measured in the ECG-triggered two-dimensional stop frame; the greatest diameter was reached immediately after the end of the P-wave in the ECG and the smallest diameter at midsystole. Thus it was possible to calculate the anulus shortening fraction as greatest diameter - shortest diameter/greatest diameter. For determination of the circumference of the tricuspid valve anulus a circular geometry was assumed. The mean values, the standard deviation and the 95% upper confidence bound for the 90th percentile were calculated. The end-diastolic right atrial area in the apical 4-chamber view was 3.0 +/- 0.8 cm2/m2 in the whole study group (males 3.4 +/- 1.8 cm2/m2 and females 2.6 +/- 0.5 cm2/m2) and the end-systolic area was 6.9 +/- 1.0 cm2/m2 (males 7.1 +/- 1.1 cm2/m2 and females 6.6 +/- 0.9 cm2/m2); the calculated value of the area shortening fraction was 56.7 +/- 9.7%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

[Echocardiographic monitoring of acute myocardial infarct following intracoronary streptolysis treatment].

Two-dimensional echocardiography is helpful in the detection of wall motion abnormalities and in the evaluation of time courses of regional function due to interventions. Of 301 patients with acute myocardial infarction treated with selective intracoronary infusion of streptokinase, 229 (76%) revealed a totally occluded infarct related vessel at the first angiography. In 64 patients a two-dimensional apical long-axis view of good technical quality could be obtained after admission, on the 1st, 2nd and 3rd day and again in the 4th to 6th week and the 9th to 14th month after the acute intervention. The collective was divided into two subgroups according to the different time interval between the beginning of symptoms of infarction and the reopening of the occluded vessel. 35 patients had a total time of occlusion of less than 4 hours (group A), while in 29 others this time exceeded 4 hours or thrombolysis was unsuccessful (group B). Using a computer system, the center of gravity of the end-systolic frame of the left ventricle was used as an inner fix point. 10 end-systolic and end-diastolic area segments were constructed. Regional wall motion was determined as a percentual change of the enclosed area, normalized to the end-diastolic area (% delta F). The ejection fraction was calculated using a disc method. In group A the ejection fraction increased from initially 46 +/- 9% to 51 +/- 8%, 52 +/- 8% (p less than 0.05) and 53 +/- 8% (p less than 0.01) on the 1st, 2nd and 3rd day, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Output↗
PubMed1983

Percutaneous transluminal coronary angioplasty in patients with stable and unstable angina pectoris: analysis of early and late results.

Percutaneous transluminal coronary angioplasty (PTCA) was performed in 50 patients with stable and in 50 patients with unstable angina pectoris, each patient showing an isolated stenosis of more than 80% of the cross-sectional area of a single coronary artery. The technical success rate was 66% in the stable groups (26 of 37 patients [70%] with left anterior descending artery [LAD], 7 of 12 patients [58%] with right coronary artery [RCA]) and 74% in the unstable group (27 of 34 patients [79%] with LAD, 10 of 15 patients [67%] with (RCA). The increase in stenotic area in the unstable group exceeding that in the stable group for LAD stenoses (41.5 +/- 15.1% vs 32.3 +/- 14.5%, p less than 0.03), while in RCA stenoses the results in the stable group were better (45.1 +/- 17.6% vs 32.7 +/- 12.3%, n.s.). One acute vessel occlusion necessitating an emergency bypass operation occurred in each group (2%). The patient in the stable group died (total mortality rate 1%). Sixty-three of the successfully treated patients were routinely restudied 6 months later. According to clinical symptoms, 23% of the stable and 36% of the unstable group were in functional classes III and IV. From the anatomical viewpoint, a restenosis (greater than 85%) was found in 17% of the stable and in 24% of the unstable group. A further spontaneous decrease (greater than 10%) of the vessel obstruction was found in 47% of the stable group and in 12% of the unstable group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

[Quantification of the function of the left ventricle using 2-dimensional echocardiography].

Left ventricular volumes and the ejection fraction can be determined by two-dimensional echocardiography. Because of methodological problems, cineventriculographic normal values can not be transferred to two-dimensional echocardiography. Therefore, normal values for two-dimensional echocardiographically determined left ventricular volumes and the ejection fraction were established in 55 normal controls. Basing on these volumes, the sensitivity and specificity of two-dimensional echocardiography for detection of impaired left ventricular function was analysed and compared with results from cineventriculography. Sensitivity for detection of a reduced ejection fraction was 84%, specificity 89% and predictive accuracy 98%. Thus, two-dimensional echocardiography can be used as a screening method for analysing left ventricular function. Analysis of beat-to-beat variation revealed that for two-dimensional echocardiography 3 consecutive beats should be analysed because evaluation of 5 instead of 3 beats increased reliability only by less than 1%. It was necessary to analyse the day-to-day variations. To separate a random error from a non-random error for an individual change, an absolute change of volumes of more than 10-12% and of ejection fraction of more than 10% had to be observed. Group changes can of course be smaller and yet significant. Intraobserver variation was not significant and below 5%. However, interobserver variability must be considered. This depends on observer experience. For a 4-chamber view no significant variability was observed, but for the RAO-equivalent view the observer variation was significant for end-diastolic and end-systolic volume. For the ejection fraction no significant difference was found. Two-dimensional echocardiography can be used for pharmacodynamic studies if percentage changes instead of absolute changes are listed.

Cardiac Output↗
PubMed1983

[Gated blood pool scanning in the diagnosis of coronary disease. A prospective study to compare cineventriculography and 2-dimensional echocardiography].

38 patients with clinically suspected coronary artery disease were studied by contrast ventriculography, 2-dimensional echocardiography and multiple gated blood pool imaging (MUGA) without stress. The results were compared with each other and with the final diagnosis confirmed by coronary angiography. The left ventricular ejection fraction is evaluated nearly identically and with sufficient accuracy by both non-invasive methods, local motion abnormalities are on the other hand diagnosed in the best way by MUGA imaging in our own cases.

Adult↗
PubMed1983

Echoventriculography -- a simultaneous analysis of two-dimensional echocardiography and cineventriculography.

Two-dimensional echocardiography underestimates left ventricular volume compared with cineventriculography. To exclude the influence of difference in heart rate, blood pressure, respiration phases and any effect of the contrast material on left ventricular function, simultaneous studies of two-dimensional echocardiography and cineventriculography-echoventriculography were performed in 46 patients. Apical two-dimensional echocardiograms in the right anterior oblique (RAO) equivalent view were recorded before and during cineventriculography in the 30 degrees RAO projection. End-diastolic and end-systolic volumes (EDV and ESV) were calculated using a disc method with a semiautomatic computer system. The echo transducer position relative to the left ventricular apex and long axis was analyzed. For EDV determined by two-dimensional echocardiography and cineventriculography, the linear regression equation was y = 0.659x + 0.8, SEE = +/- 26.2 ml, r = 0.907. For ESV, the regression equation was y = 0.571x + 17.8, r = 0.938, SEE = +/- 18.6 ml, and for ejection fraction (EF) it was y = 0.606x + 13.0, r = 0.803, SEE = +/- 9.1%. Injection of contrast material resulted in only a small increase of stroke volume, caused by an increase of EDV as analyzed by echoventriculography. In all but two patients, the transducer position was found to be anterior and superior to the left ventricular anatomic apex, as evaluated by filming the echo transducer position during cineventriculography in 46 patients in the 30 degrees RAO projection and in 15 patients consecutively in the 60 degrees left anterior oblique and 30-40 degrees cranial projections. Thus, tangential cuts of the ventricle resulted in underestimation of diameters, long axis and ventricular volumes. These methodologic problems are exacerbated by slice-thickness artifacts. Furthermore, different outlining of left ventricular contour -- outer border of ventricular trabeculae for cine ventriculography and inner border for two-dimensional echocardiography -- seemed to result in underestimation of volume by echocardiography.

Adult↗
PubMed1982

Apical region of the crayfish retinula.

The base of the crystalline tract, the distal part of the eighth retinular cell and its rhabdomer constitute a structural unit in the apical region of the retinula of Astacus fluviatilis and A. leptodactylus, shielded from the blood by a special covering cell.

Animals↗
PubMed1982

[Ocular symptoms and leukemia in childhood].

Findings in a total of 200 children suffering from leukemia were evaluated. Ocular symptoms were found in 26% of the cases. Typically, fundus hemorrhages were found in the initial stage, leukemic infiltrates in the final stage and papilledema in the meningosis leucaemica stage. In patients with ophthalmologic changes the survival time was shorter than in patients with no ocular involvement. Ophthalmological "dispensaire" treatment is generally recommended.

Child↗
PubMed1982

Morphometric investigations in mitral stenosis using two dimensional echocardiography.

A method is proposed for comparing the orifice size and the morphology of stenotic mitral valves, removed intact at the time of replacement, with the preoperative two dimensional echocardiographic cross-sections. The excised mitral valve apparatus is suspended on a specially constructed mounting. To avoid shrinkage the orifice is stabilised with an airfilled balloon. A radiography is taken directing the x-ray beam perpendicular to the valve orifice. In 40 of 51 patients this method provided the means of relating the echocardiographic cross-sections to the morphology of the valve. Planimetry of the valve area compared favourably with the postoperatively determined orifice size. Agreement was found in 34 of 40 patients in orifice shape between preoperative echocardiograms and x-rays of th excised valve. The relation between intraoperative estimation of size of the valve, using dilators with known diameters, and the postoperative results was less favourable. Areas of calcification were identified on echocardiography as dense conglomerate echoes. In 30 patients (75%) the localisation of calcium deposits and in 67% the degree of calcification was in agreement with the x-rays of the valve taken after operation. In addition to determination of the area, two dimensional echocardiography allows detailed studies of the stenotic valves, and is of particular importance for planning operative treatment.

Adult↗
PubMed1982

Percutaneous transluminal coronary angioplasty immediately after intracoronary streptolysis of transmural myocardial infarction.

Percutaneous transluminal coronary angioplasty (PTCA) was performed in 21 patients with acute myocardial infarction (AMI) treated by intracoronary infusion of streptokinase within 8 hours after the onset of symptoms. Streptolysis therapy began a mean of 3.6 +/- 1.2 hours (+/- SD) after the onset of symptoms. The vessel was occluded in 14 patients and highly stenosed in seven. After the infusion of 67,300 +/- 63,200 IU of streptokinase over 26.1 +/- 21.5 minutes, patency of the occluded vessels was reached. PTCA as performed 20-60 minutes after the end of streptokinase treatment in 19 patients and 24 and 31 hours after treatment in two patients. The dilation was successful in 17 patients (81%). The degree of vessel obstruction was reduced from 90.2 +/- 7.3% to 58.6 +/- 19.5% (area method) and from 71.4 +/- 12.4% to 39.2 +/- 19.7% (diameter method). The improvement was 31.5 +/- 18.4% and 32.2 +/- 19.3%, respectively. No reocclusion was induced by PTCA. Twenty patients were discharged. One died during hospitalization; at autopsy, the treated vessel was still patent. During the follow-up period, two reinfarctions and one asymptomatic reocclusion occurred. The clinical findings during the hospital course and the follow-up period were compared with those of a control group of 18 patients with AMI and comparable coronary stenoses who were treated only with streptokinase infusion. Four of these patients had a reinfarction during the hospital course, and three died during the follow-up period. PTCA can be performed safely and successfully immediately after intracoronary infusion of streptokinase in patients with AMI. By reducing the subtotal stenosis, this treatment contributes to the reperfusion of the ischemic myocardium, diminishes the risk of a reocclusion and seems to improve the prognosis.

Adult↗
PubMed1982

[Right ventricular volume determination by two-dimensional echocardiography and radiography in model hearts using a subtraction method].

The irregularity and complexity of the right ventricle is the reason why no accurate method for right ventricular volume determination exists. A new method for right ventricular volume determination particularly for two-dimensional echocardiography was developed-it is called subtraction method-and was compared with the pyramid and Simpson's methods. The partial volume of the left ventricle and septum was subtracted from total volume of right and left ventricle including interventricular septum. Thus right ventricular volume resulted. Total and partial volume were computer-assisted calculated by use of biplane methods, preferably Simpson's rule. The method was proved with thinwall silicon-rubber model hearts of the left and right ventricle. Two orthogonal planes in the long-axis were filmed by radiography or scanned in a water bath by two-dimensional echocardiography equivalent to RAO and LAO-projections of cineangiocardiograms or to four- and two-chamber views of apical two-dimensional echocardiograms. For calculation of the major axes of the elliptical sections, summed up by Simpson's rule, they were derived from the LAO-projection and the four-chamber view, respectively, the minor axis approximated from the RAO-projection and the two-chamber view. For comparison of direct-measured volume and two-dimensional echocardiographically determined volume, regression equation was given by y = 1.01 x -3.2, correlation-coefficient, r = 0.977, and standard error of estimate (SEE) +/- 10.5 ml. For radiography, regression equation was y = 0.909 x + 13.3,r = 0.983, SEE = +/- 8.0 ml. For pyramid method and Simpson's rule, higher standard errors and lower correlation coefficients were found. Between radiography and two-dimensional echocardiography a mean difference of 4.3 +/- 13.2 ml, using subtraction method, and -10.2 +/- 22.9 ml, using pyramid method, as well as -0,6 +/- 18.5 ml, using Simpson's rule, were calculated for right ventricular volume measurements. Differences were not significant. The subtraction method seems to be useful for calculation of right ventricular volume by radiography as well as two-dimensional echocardiography. Further studies in isolated hearts and patients are necessary for final judgment of the accuracy of this new method.

Blood Volume↗
PubMed1981

Treatment of unstable angina pectoris with percutaneous transluminal coronary angioplasty (PTCA).

Percutaneous transluminal coronary angioplasty (PTCA) was performed in 40 patients (34 male, 6 female; 51.0 +/- 8.5 years) with the typical clinical picture of unstable angina. All had a short history of pain (2.9 +/- 2.0 months), angina at rest, transient ST and/or T wave changes during this period, and little or no enzyme elevations. The patients had a total of 41 stenoses (39 single, one double; one main-stem, 26 left anterior descending, 14 right coronary artery). The degree of the stenoses was 95.5 +/- 4.9% (area method) and 81.8 +/- 10.7% (diameter method). PTCA was successfully performed in 26 cases (63%), reducing the stenoses to 61.5 +/- 12.4% (area method) and 39.1 +/- 10.0% (diameter method). One patient (2.5%) received an immediate bypass operation because of an acute vessel occlusion. Eleven of the 14 not successfully treated patients received an aortocoronary bypass within the next three to 35 days. All still had symptoms of unstable angina. Three patients refused operation. Their treatment consisted of nitroglycerin, beta-blockers and nifedipin. Seventeen of the 26 successfully treated patients were restudied after 4.9 +/- 1.7 months. The degree of stenosis had risen to 69.2 +/- 17.4% (area method). While the stenoses in 12 patients were equal or less than before PTCA, stenosis recurred in five cases. Two patients were successfully retreated. PTCA can be performed with a good early success rate and a low concentration rate in patients with unstable angina. Relief of pain and improvement of blood supply to the jeopardized myocardium can be provided immediately and with a limited amount of expense. The method can therefore be regarded first-stage treatment in such patients.

Adult↗