PubMed Health⌕ Search

Biomedical subjects

K Berwing

Publications and source records attributed to K Berwing.

5 recordsLinked to original sources
PubMed1990

[The assessment of myocardial perfusion using contrast echocardiography].

A brief survey is given on the state of the art of qualitative and quantitative myocardial contrast echocardiography as well as on the contrast agents used. Exact qualitative assessment of coronary perfusion areas is possible. In addition, myocardial areas of collaterals of less than 100 microns in diameter can be visualized and measured that were not seen by routine coronary angiography. Quantitative analysis was done in 5 normal subjects and 16 patients with coronary artery disease before and after right ventricular stimulation (170 bpm over 75 s). While decay half time (T1/2) remained unchanged in normal subjects before and after pacing (7 +/- 4 s vs 7 +/- 5 s), it increased significantly from 5 +/- 1 to 16 +/- 1 s in patients with coronary stenoses between 50% and 75%. Stenotic area reduction greater than 75% had significant prolongations of T 1/2 = 12 +/- 7 s already at rest with further prolongation to 36 +/- 17 s (p less than 0.05) after pacing. Regional wall motion in these areas, however, was not significantly altered either in the fixed axis or floating axis system. Following dipyridamole hyperaemia (0.56 mg/kg i.v.), normal subjects showed a significant shortening of T 1/2 (6 +/- 2 vs 1.6 +/- 1; p less than 0.01; n = 5), while T 1/2 of patients with multiple vessel disease was prolonged from 9 +/- 6 to 15 +/- 6 s (p less than 0.01; n = 7). This prolongation was not uniform, since some myocardial areas were found to be hyperaemic after dipyridamole. One patient showed an opening of antegrade collaterals following dipyridamole. In first results myocardial contrast echocardiography proved capable of recognizing ischaemic and hyperaemic myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Echocardiographic imaging of the left ventricle by peripheral intravenous injection of echo contrast agent.

With the use of a new echo contrast agent (ECA) that consists of a suspension with microbubbles (100% less than 3.9 micron in a moving system), we were able to opacify the left ventricle by peripheral intravenous injection in 124 of 130 patients (95%) without shunt connection. In 12 patients with aortic valve disease we measured the opacification of the right and left ventricles videodensitometrically by means of increasing doses. Dose 1 (8.7 ml ECA) and dose 4 (50 ml ECA) led to no significant difference in intensity in the right ventricle (168 +/- 32 vs 184 +/- 16 units, respectively; p greater than 0.05); however, opacification of the left ventricle was significantly more evident after dose 4 (60 +/- 60 vs 88 +/- 62 units, respectively; p less than 0.05). On the basis of the farthest distance reached by the regurgitant microbubbles from the aortic valve, the severity of regurgitation was graded on a four-point scale; the results were compared with those of aortography. A significant correlation (r = 0.98, n = 9) was found between ECA grading and aortography in the evaluation of the severity of aortic insufficiency. In addition, flow characteristics in patients with mitral stenosis, aortic insufficiency, and the regurgitation jet in incompetent aortic prosthesis in connection with diastolic inflow over the mitral valve were described. Moreover, it was possible to differentiate between inflow of ECA into the left atrium via an atrial septal defect and across the pulmonary vascular bed. No adverse effects were reported by the patients. Left ventricular end-diastolic volume index, end-systolic volume index, stroke volume index, and ejection fraction were determined before and after intravenous injection of increasing doses of ECA by means of the area-length method of Sandler and Dodge. Even after dose 4 we observed no significant changes in left ventricular function. The values before and after injection were in the range of intra- and interobserver reproducibility. Only three patients reported a slight taste sensation. In nine patients with a history of allergies there were no side effects.

Aortic Valve Insufficiency↗
PubMed1985

[Comparative echocardiographic volume determinations using a dynamic heart model].

Using a dynamic and symmetrical cardiac phantom different echocardiographic mathematical models (Simpson 7 slices, area-length method, Simpson 2 slices and method according to Teichholz) were compared. 9 different end-diastolic (EDV) and end-systolic (ESV) volumes, 9 different stroke volumes (SV) and ejection fractions (EF) were used. EDV and ESV varied between 39-298 ml; SV between 29-100 ml and EF between 14-46%. In addition 10 fixed volumes of the same shape were evaluated using the same echocardiographic mathematical models. While symmetrical fixed volumes can be assessed correctly (r = 0.97-0.98), apart from the formula according to Teichholz (r = 0.89, significant underestimation of volumes), the correlation coefficients decrease using a dynamic cardiac phantom. In the modification of Simpson with 7 slices the best correlation was found for all parameters (EDV: r = 0.93; ESV: r = 0.94; EF: r = 0.87; SV: r = 0.81). The biplane area-length method has no advantages over Simpson's rule with 2 slices in the short axis; for symmetrical models both methods are comparable, both having high correlation coefficients (for volumes r = 0.85 and r = 0.88; for EF 0.78 and 0.84). Using the method according to Teichholz symmetrical volumes can be well assessed (r = 0.90), for the determination of EF the correlation coefficient decreases to r = 0.65 and for stroke volume to 0.33, reflecting no significant correlation to the actual SV. Possible causes for a poorer correlation are discussed for moving objects as opposed to the fixed volumes.

Cardiac Output↗
PubMed1978

On the problem of optimum digitlaization in man.

The low therapeutic index of cardiac glycoside requires an optimum individual digitalization. This is also a difficulty in the case of known serum glycoside concentrations because individual differences of biochemical and physiological factors (which influence both therapeutic and side effects) are important. As a rule the physician's criterion for an optimum digitalization is that side effects are avoided. This investigation attempted to find a measure for the effect of glycosides by noninvasive recording of parameters of myocardial contractility (systolic time intervals, STI). The measurements were made under oral digitalization with digoxin (Dilanacin). The serum glycoside concentration was determined by the radioimmunoassay method. The changes in STI were investigated in the rage of 1 to 3 ng digoxin per ml serum. In this concentration a significant correlation was demonstrated between STI shortening and glycoside level. It was found that the shortening of STI was maximum at the lowest concentration (1 ng/ml). It appears that the control of STI is for the physician a useful aid for an optimum digitalization in man.

Adult↗