Biomedical subjects
Publications and source records attributed to E Knapp.
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A patient with mitral insufficiency is described who developed severe hemolytic anemia six months after mitral valvuloplasty. Various laboratory tests suggested that the cause of the hemolysis was mechanical. A second heart operation was therefore performed which revealed intact valve function. With respect to the mechanical cause of hemolysis a bioprosthesis was implanted, but the patient died shortly after this operation. Since similar cases are not reported in the literature the authors invite for discussion of this case.
30 gravid women between the ages of 18 and 38 years who had gone into premature labour of unknown etiology were examined with respect to cardiac output and various other cardiovascular parameters in the standing, supine and left lateral positions. Measurements were carried out using an impedance-cardiography. A group of 30 women of similar age and duration of pregnancy but not in premature labour was also tested as controls. In the standing position, the test group showed a cardiac output which was 15% less than that of the controls. Statistically this was highly significant (p less than 0.005). No difference was found in the supine and left lateral positions. These results are in agreement with the literature, but with the method used in this study, an invasive, or X-Ray procedure is avoided. The physiology of the cardiovascular system in pregnancy and the means by which premature labour may be prevented, are discussed.
Out of 1800 patients examined for valvular heart disease, 19 were found to have the mitral valve prolapse syndrome (MVPS). The relevant literature is reviewed and the epidemiology and aetiology of the disease are discussed. 50% of the patients had a history of endomyocarditis. The special diagnostic value of echocardiography is emphasized. Sudden death (observed in 2 young patients) and the grave complication of bacterial endocarditis (observed in 3 patients and usually caused by Streptococcus viridans) can occur in this condition. Prophylactic therapy with beta-blocking drugs and antibiotics seems warranted. The case history of one patient with MVPS under observation for eight years, who developed bacterial endocarditis from a dental focus is reported in greater detail as a typical case.
This project was to provide a further indication for the triggering of central-nervous effects by a 50 - cycle alternating field with a field strength of 5.300 V/m. Previous studies already raised the suspicion of an effector mechanism of this kind: for instance, the nucleus temperature of rats sank under field influence. The same effect is triggered in mice and rats by prescribing centrally stimulating pharmaca. Furthermore, a rise in diastolic blood pressure with a simultaneous drop in heart rate was described for human subjects. We were able to demonstrate the latter effect in laboratory animals (rats). The experiments under consideration resulted in a significant rise in norepinephrine content of the rats' brains following brief exposure of 15 min length. The measured data after 10 d fell highly significantly below those of the untreated controls and remained approximately at this lowered level until the end of field exposure (21 d). Changes in "turn over" of the norepinephrine metabolism of the brain represent an important indicator for the demonstration of the stimulation of central-nervous structures. Our findings therefore substantiate the presented hypothesis of a central-nervous point of attack by electrical energies.
The article reports on a block formation in the lumbar vertebrae of a woman athletic. In the authors' opinion, such an anomaly has not yet been described. The article demonstrates on the basis of a detailed descussion of developmental anatomy that the block formation extended from L 3 to L 5, L 4 being merely a "quarter vertebra". The findings and the complaints resulting thereform prompt the authors to demand that in persons aspiring to become top-performance sporstmen. The locomotor system must be subjected to a thorough examination.
The effect was studied of therapeutic total starvation of two weeks' duration on myocardial performance in 12 obeses patients. Half of these subjects were trained for 10 minutes daily on a bicycle ergometer, whilst the other half had no training. After two weeks of total fasting no significant changes were observed either inter- or intracollectively with regard to systolic time intervals, ejection fraction and the index of myocardial contractility, nor in respect to serum electrolytes. Physical training had no influence on the systolic time intervals and the other noninvasive parameters of left ventricular performance. The inclusion of previous data obtained in a similar investigation enabled the establishment of a correlation between the serum potassium level and the ejection franction.
The effect of an intravenous bolus of 1 mg/kg Ro 11-1781, a new calciumantagonist, on sinus node automaticity and intracardiac conduction was studied by His-bundle electrography and atrial stimulation. During sinus rhythm, no significant action of Ro 11-1781 on rate, P-A-interval, A-H interval, and H-V-interval was observed. The sinus node recovery time remained unaltered. On atrial stimulation, the St-H-interval was significantly (p less than 0.001) prolonged after Ro 11-1781. Wenckebach Periods occurred at lower stimulation rates in all patients after Ro 11-1781. It is concluded that Ro 11-1781 prolongs av nodal conduction and may be of therapeutic value in the treatment of supraventricular arrhythmias.
The action of nitroprusside on pulmonary circulation was studied in patients with pulmonary hypertension due to mitral stenosis (group I) or to primary lung disease (group II) and in patients with normal pulmonary artery pressure (group III). Nitroprusside 20 microgram/min decreased systolic and mean pulmonary artery pressure in groups I and II while higher doses were necessary to produce a similar pressure reduction in group III. Diastolic pulmonary artery pressure was reduced by 40 microgram/min nitroprusside in all groups. Systemic arterial pressure declined during nitroprusside infusion similary in all groups in a dose-related manner; cardiac index remained unaltered. Pulmonary vascular resistance was reduced by 20 microgram/min nitroprusside in group I, not below 200 microgram/min nitroprusside in group II and remained unchanged in group III. Peripheral vascular resistance declined in all groups with nitroprusside infusion. The study suggests direct relaxation of the pulmonary vasculature by nitroprusside.
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Nitroprusside was infused intravenously (20, 40, 80 and 200 mug/min) in nine patients with pulmonary hypertension due to mitral stenosis (group I), nine with precapillary pulmonary hypertension associated with primary lung disease (group II) and nine with normal pulmonary-arterial pressures (group III). The mean pulmonary-arterial pressure was markedly reduced at a rate of 20 mug/min in group I and II, while higher doses were necessary in group III to produce a similar effect. Mean arterial pressure was decreased in all three groups and was dose-related. Heart rate rose, stroke volume fell during nitroprusside administration, while cardiac output remained unchanged. Pulmonary vascular resistance was reduced on 20 mug/min in group I, but only on 200 mug/min or more in group II, and unchanged at all dosages in group III. Peripheral vascular resistance declined in all three groups on nitroprusside infusion, which is apparently of value in the short-term lowering of pulmonary hypertension.
The haemodynamics at rest of 10 patients (mean age 42.6 years) with terminal renal failure treated by intermittent haemodialysis were studied over a period of 8 to 22 months by non-invasive methods. Additionally bicycle exercise testing was performed. After 13 months there was a reduction in cardiac index from 3.37 +/- 0.75 L/Min./m2 to 2.94 +/- 0.51 L/Min./m2 (p less than 0.05) and of the left ventricular minute work index from 6.21 +/- 1.60 mkp/Min./m2 to 5.71 +/- 1.36 mkp/Min./m2 (p less than 0.02). The blood pressure, index of peripheral resistance, systolic time intervals, arm-ear time and the ejection fraction showed no significant variations. Left ventricular failure was not detectable at rest, but the work capacity on exercise testing was reduced during the entire period of investigation without significant variation.
Determination of cardiac output by impedance cardiography exhibited perfect agreement with determinations performed by the Fick principle (r = 0.905; p less than 0.001); the measurements were carried out on 11 patients without valvular disease, 15 patients with mitral stenosis, 5 patients with aortic stenosis and 4 patients with combined aortic valvular disease. Impedance cardiography tends to give an underestimate of the cardiac output in patients with mitral insufficiency (N = 7) and in cases with combined mitral valvular disease (N = 9); in patients suffering from aortic insufficiency (N = 6), combined valvular disease (N = 5) and left to right shunts (N = 10) the cardiac output is often overestimated. Impedance cardiography is also suitable for determination of the cardiac output under exercise testing conditions up to submaximum ranges. This was demonstrated on 30 well-trained sportsmen, in a comperison and oxygen consumption testing (r = 0.937; p less than 0.001). Zo impedance does not change in healthy persons during exercise testing. Pharmacological investigations can be performed using impedance cardiography; a reduction in pressure values in pulmonary hypertension was demonstrated under the influence of nitroprusside. The stroke volume of a single cardiac revolution was, more over, measured in 12 patients with implanted pacemakers. P-ST intervals were 70--200 msec. The increase in cardiac output by 33% indifies the opinion that in certain cases, especially in young people, atrial synchronous pacemaker systems should be tried, despite the reported pitfalls and lack of success to date.
The purpose of the study was to evaluate the effects of nitroglycerin on the mechanical and metabolic performance of the mammalian heart without interference from peripheral vascular and neurohumoral influences. Isolated rat hearts were perfused with a buffer containing 1 mug of alcoholic nitroglycerin/ml or an equivalent amount of alcohol. Mechanical performance was analyzed during external and isovolumic work; all hearts were subjected to mild hypoxia. Heart rate was kept constant by pacing. At constant atrial filling pressures end diastolic pressures and calculated wall stiffness were not significantly different for controls and nitroglycerin. Afterload, as quantitated by mean aortic pressure, was the same for both groups. Peak-systolic left ventricular pressure and dp/dt max during ejection and isovolumic work were significantly reduced by hypoxia (p less than 0.001), but not changed by nitroglycerin. Cardiac output, mean systolic left ventricular pressure, work, oxygen consumption, and calculated efficiency were decreased by hypoxia (p less than 0.001); lactate production was enhanced by the hypoxic state (p less than 0.001). Nitroglycerin had no influence on these parameters in either state. It is concluded that at constant rate, preload and afterload nitroglycerin has no effect on the mechanical performance and energy formation by aerobic and anaerobic means in the fully oxygenated and mild hypoxic state.
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