Biomedical subjects
R Erbel
Publications and source records attributed to R Erbel.
[Pressure-dimension analysis of the poststimulation potentiation--influence of heart rate and ventricular function (author's transl)].
The mechanism of poststimulation potentiation (PSP) was studied in 17 patients with coronary artery disease by simultaneous pressure-dimension analysis. The left ventricular pressure (LVP) was measured by catheter-tip-micromanometer and LV diameter by M-mode echocardiography. The pressure signals were digitised and analysed on line by 400 Hz. The pressure-dimension tracings were additionally analysed half-automatically. Measurements were done during right atrial pacing at 80, 120, 140 beats/min and during the poststimulation period. 1. Right atrial pacing increased the rate of LV pressure development (dp/dt max), the rate of pressure fall (dp/dt min), the velocity of circumferential fiber shortening (VCF mn), and fiber dilatation (vcf mx) dependent on heart rate and cardiac function. 2. LV enddiastolic diameter (LVEDD) reached during the first poststimulation period the starting point independent on pacing rate and cardiac function. LV enddiastolic pressure (LVEDP) showed a slight overshoot. PSP resulted in an increase of LVP, dp/dt max, VCF mn, and the velocity of posterior wall motion, dp/dt min, VCF mx, and the velocity of posterior wall relaxation decreased, however, with the first post-stimulation beat. 3. The PSP was dependent on atrial pacing rate. The higher the pacing rate the higher the PSP. dp/dt max increased after cessation of 120/min for +29% and after 140/min for +38%. The PSP for the preload independent parameter of contractility, V-40, was, however, equal for both heart rates +25% and +28% respectively. 4. Another determinant of PSP was cardiac function. The PSP was relatively higher in patients with reduced ejection fraction than in patients with a normal ejection fraction: dp/dt max +55% and 25%, VCF mn +18% and +7% respectively. From the derived ventricular function curves, it could be shown, that atrial pacing reflected an increase in LV contractility (Bowditch effect), whereas PSP reflected an increase in LV performance by the Frank-Straub-Starling (Woodworth staircase) effect on a new left ventricular function curve, which was shifted to the left by atrial pacing.
[Pharmacodynamic studies in suicidal digoxin poisoning (author's transl)].
In two patients with suicidal digoxin poisoning the correlations between serum digoxin concentration and changes in the duration of QTc and the flattening of the T-waves were studied. The digoxin serum half-life following suicidal digoxin poisoning was in the first patient (10 mg beta-acetyl derivative of digoxin) 77 h, prolonged cause of renal insufficiency, and in the second patient 39.6 h. (20 mg beta-acetyl derivative of digoxin). In both patients the digoxin induced flattening of the T-wave reached a plateau of maximum efficacy at a serum level of 2-3 ng/ml with no further change up to a serum level of 13.2 ng/ml and 9.6 ng/ml respectively. A linear correlation, however, was found between the digoxin serum concentration and the digoxin induced shortening of QTc, r = 0.88 and r = 0.92 respectively. A plateau maximum efficacy was not found. The regression equations were y = -12.0 chi + 430.8 and y = -8.0 chi + 391.9 respectively. The shortening of QTc is therefore an important parameter for the diagnosis of digoxin poisoning. It can be determined very quick with no methodical problems.
[The vulnerability of the human ventricular myocardium after premature stimulation. Electrophysiological results (author's transl)].
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[Special diagnostic procedures in atrial tumours of the heart (author's transl)].
A vascular myxoma which prolapsed into the mitral valve was found in the left atrium of a 47-year old man. Two-dimensional ultrasonic tomography yielded relevant non-invasive diagnostic information on the pattern of movement of the pedunculated tumour. Highly accurate determination of the tumour volume was achieved via angiocardiography and videometry. Coronography of the tumour vessels allowed identification of an unusual point of insertion of the myxoma. The risk of obstruction of the mitral orifice was documented haemodynamically by a steep gradient above the mitral valve when holding breath during the expiratory phase.
Dose-response relationships and plasma concentrations of digitalis glycosides in man.
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[Exertion ECG during therapy with cardiac glycosides].
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[Propranolol versus placebo in long-term treatment of patients with mitral valve prolapse (author's transl)].
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[Evaluation of regional myocardial dysfunction by echocardiographic pressure-dimension analysis (author's transl)].
Ecg, left ventricular pressure measured by micromanometer-tipped catheter, and dimension measured by echocardiography were simultaneously recorded in 24 patients with coronary artery disease and 9 normal subjects. In analogy to pressure-volume diagrams, pressure-dimension diagrams were constructed, the area in systole and diastole and the cycle efficiency calculated. In patients with coronary artery disease the normal rectangular shape of the pressure-dimension diagram shows two typical deviations: 1. a dimension decrease during isovolumetric contraction and dimension increase during isovolumic relaxation in 42% of the patients, in 31% in patients with stenosis of the right coronary artery, in 56% in patients with stenosis of the left anterior descending coronary artery, in 85% in patients with a reduced ejection fraction. 2. An exact reflected image was found only in patients with stenosis of the right coronary artery and reduced ventricular function in 23%. The abnormal dimension changes are the result of an asynchronized contraction and relaxation with inward movement of one part and outward movement of another part of the left ventricle. These changes are caused by ischemic or fibrous areas of the ventricle. Independent of left ventricular pressure and dimension changes we found that the cycle efficiency was useful to study regional myocardial work. It ranged from 81.7 +/- 2.5% in the normal subjects to 74.8 +/- 1.8% in patients with reduced ventricular function. From the diastolic part of the pressure-dimension diagram the regional compliance was calculated. Dependent on coronary artery disease the regional compliance was decreased even at rest.
[Echocardiographic pressure dimension analysis in coronary heart disease].
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[Exercise test during digitalis therapy].
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[Recent aspects on basic drug therapy of acute myocardial infarct].
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[Intramyocardial pressure and changes in local contractility].
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[A study to the analysis of systolic time intervals (author's transl)].
For evaluating the degree of accuracy of the STI, a study on 120 healthy young male volunteers was performed. Under standardized conditions ecg, phonocardiogram and carotid arterial pulse were recorded. The following variables were measured: heart cycle interval (RRI), electrical systole (QT), electromechanical systole (QS2), and left ventricular ejection time (LVET). The arithmetic mean was utilized for the consecutive beats 1--5, 1--10, 1--15, and 1--20. The mean of the beats 1--20 was assumed as reference. The increase of the analysed heart cycles from 5 to 20 lead to a decrease of the standard error of RRI, which raised the degree of accuracy. The standard error for RRI decreased from 27.9 to 9.9 ms. Already the analysis of 5 consecutive beats for QT, QS2, and LVET reached the line of identity of the correlation slope compared to 20 analysed heart cycles. The standard error was very small (2.0; 2.9; and 3.0 ms). For clinical-pharmacological studies, the evaluation of 5 consecutive heart cycles for measuring STI leads to a very high degree of accuracy. For an exact measuring of RRI, it is necessary to analyse at least 20 heart cycles.
[Influence of digoxin upon the exercise ECG of healthy men (author's transl)].
Cardiac glycosides may cause in the exercise ECG of healthy persons S-T segment depressions, which imitate a coronary insufficiency. If this method of examination is to be carried out in diagnosing coronary heart disease, it is - therefore - recommended in many cases to discontinue, at all events, an eventual digitals therapy before the examination in order to avoid falsely positive results. 23 healthy men (average age 30.2 years) were applied digoxin of medially quick saturation over seven days. Exertion electrocardiograms at the bicycle ergometer were registered before and after digoxin application. In five further cases, plasma glycoside concentrations were evaluated by 86Rb erythrocyte assay; upon the degree of saturation used, these concentrations - on the sixth and seventh day - amounted to x = 1.03 ng/ml. The following items manifested after digoxin administration, under stress and after resting: Retardation of heart rate, declination of T amplitude, and individually to a very different extent - depression of the S-T segment. After application of digoxin, only 8 of the 23 test persons demonstrated S-T depressions that would have corresponded entirely to the conditions of a "coronary insufficiency". Thus, it appears to be justified to carry out - first of all and in order to exclude the possibility of a coronary insufficiency - an exertion electrocardiogram, without interruption of the glycoside therapy, also in patients who are undergoing a digitalis therapy. The reason for this measure is the fact that in healthy persons only one third of the cases must be expected to show a falsely positive result. If, however, significant S-T depressions occur, the examination has to be repeated after a sufficiently long-lasting glycoside-free interval.
[Letter: Possibilities of preserving ischemic myocardium].
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[Effect of digoxin on the stress ECG in healthy persons].
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[The effect of contrast medium injection into the left ventricle on systolic and diastolic ventricle function].
The influence of contrast medium on systolic and diastolic left ventricular function was studied in eight patients with coronary heart disease and in five dogs during and five minutes after ventriculography. Two biplane ventriculograms were performed in 5-minute intervals, in the dogs an additional one after 10 minutes. 0.66 cc/kg BW of sodium methyl-glucamin-iothalamate were injected during diastole into the left ventricel. 1. During ventriculography there are only slight changes of left ventricular volumes, pressures and diastolic compliance. The first four opacified heart cycles can be evaluated for the analysis of left ventricular function. 2. In patients with coronary heart disease there are much more pronounced alterations of systolic ventricular function 5 minutes after Ventriculography than in the normal dog. The ischemic ventricle has a reduced tolerance for volume load and negative inotropic effect of contrast media. In patients and dogs diastolic compliance is significantly increased 5 minutes after the injection of contrast medium. After 10 minutes however in the dogs compliance is significantly decreased. Analysing left ventricular function by repeated ventriculographies one has to take into account that the function is altered by the first angiogram. The degree of the changes depends on the initial hemodynamic conditions and on the time interval between the ventriculograms.