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Biomedical subjects

E Wolner

Publications and source records attributed to E Wolner.

At least 361 records · Page 20Linked to original sources
PubMed1985

Testing of biomaterials, accelerated ageing.

The residual elongation is a critical property of materials used for manufacturing diaphragms of artificial hearts. It is therefore important to check goods received or to control manufactured diaphragms, whether their creep properties are within the required limits. Ordinary creep tests take at least several months, while the release of goods received or diaphragms manufactured should be possible within a few days. Acceleration of the creep test by increasing the test temperature permits an estimation whether the creep properties of a material are within the required limits within a week.

Heart, Artificial↗
PubMed1985

[Indications for and the results of continuous arteriovenous hemofiltration (CAVH) in heart surgery patients].

In 326 cardiac surgical patients equal results could be achieved when CAVH was performed either before, during or after extracorporal circulation. Following CAVH improvement of haemodynamic parameters as well as pulmonary function could clearly be shown. This improvement was mainly due to the clearance of all cardiopulmonary toxic substances weighing less than 50.000 daltons. Since the negative inotropic effect of MDF (MW 800 to 1000 daltons) is known to be an important reason for "low cardiac output syndrome" elimination of MDF is one advantageous benefit of CAVH apart from dehydration. By means of bioassays our experiences demonstrated the capability of CAVH to clear MDF to a remarkable degree.

Blood↗
PubMed1984

Reduction of infarct size induced by pressure-controlled intermittent coronary sinus occlusion.

The effect of pressure-controlled intermittent coronary sinus (CS) occlusion on myocardial infarction (MI) size was evaluated. A device for this purpose was developed that consisted of a balloon catheter and pump system that produced controlled, intermittent occlusion of the CS and used CS pressure as a feedback to determine the duration of occlusion. It was hypothesized that proper selection of occlusion and non-occlusion times would both facilitate improved retrograde flow to ischemic areas and allow for more complete venous washout of metabolites. In 13 treated dogs and 12 control dogs before treatment, myocardium at risk of MI was estimated by injection of technetium-labeled microspheres. Intermittent CS occlusion was then begun, 15 minutes after coronary artery occlusion, and continued until termination of the experiment 6 hours later. Postmortem determination of infarct size was performed using the triphenyltetrazolium chloride staining technique. Intermittent CS occlusion begun 15 minutes after coronary artery occlusion and continued for 6 hours resulted in a 45% average reduction in MI size (p less than 0.001). During CS occlusion, the sinus systolic mean pressure increased from 10 to 44 mm Hg, while the distal coronary artery mean pressure increased by an average of 36% (from 22 to 30 mm Hg, p less than 0.05). These results suggest intermittent occlusion may be an effective treatment for evolving MI. This therapy, used alone or combined with other therapies (e.g., administration of pharmacologic agents), appears to have great clinical potential.

Animals↗
PubMed1984

Preventive insulin administration for myocardial protection in cardiac surgery.

The object of this study was to determine whether high doses of insulin administered preventively in combination with glucose and potassium exert a protective effect upon the myocardium. This approach should result in a preoperative accumulation of the myocardial glycogen stores with an increased anaerobic provision of energy-rich substrates (ATP) during coronary ischemia. Two comparable groups of seven dogs each, undergoing experimental extracorporeal circulation (ECC) with 90-min aortic cross-clamping were examined. Cardiac output (CO), systolic left ventricular blood pressure (pventr), left ventricular enddiastolic pressure (LVEDP), mean central venous pressure (CVP), and heart rate (HR) were recorded at left atrial (LA) pressures of 5, 10, 15, and 20 mmHg in order to construct ventricular function curves. These data were registered prior to the onset of ECC (preischemic value), after termination of ECC and after two 10-min periods of reperfusion. The first group served as control and the second group received high iv doses of insulin (total 25 U/kg) within 60 min prior to the onset of the ECC. In the control group, pventr and CO after termination of the ECC and after the first reperfusion were significantly (P less than 0.05) less than the preischemic values; after the second reperfusion they reached the preischemic range. In contrast, pventr and CO in the insulin group already were within the preischemic range at the termination of the ECC. After the first and the second reperfusion, CO was even greater than the preischemic value. LVEDP changed inversely, while CVP and HR showed no significant differences.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Improvement of cardiac preservation by preoperative high insulin supply.

Therapeutic administration of high doses of insulin achieves a shifting of metabolism to glycogenesis and glycolysis. The result is an accumulation of the myocardial glycogen stores and an improvement of glucose utilization as well. If on that basis an increased anaerobic provision of adenosine triphosphate will be maintained in the myocardium during ischemia, the myocardial cell viability during aortic cross-clamping will be saved as well. Thus a preventive insulin supply will preserve the heart from ischemic damage. Twenty patients undergoing mitral valve replacement were investigated in two randomized groups. One group received insulin (1 U/kg/hr) together with a 33% glucose infusion (0.5 gm/kg/h) and potassium (0.25 mEq/kg/hr) from the onset of anesthesia until aortic cross-clamping. The control group received Ringer's lactate at the same infusion rate. After an average ischemic time of 26 minutes, an excised papillary muscle tip was immediately plunged into liquid nitrogen and the content of adenosine triphosphate, adenosine diphosphate, and creatine phosphate was determined. The adenosine triphosphate/diphosphate quotient and the energy charge potential were calculated. The mean adenosine triphosphate content in the insulin group was 7.43 mumol/gm wet weight and was significantly (p less than 0.01) higher than that of the control group (4.28 mumol/gm). The mean ADP content was 1.43 mumol/gm in the insulin group versus 1.81 mumol/gm in the control group. The mean creatine phosphate content was again significantly (p less than 0.05) higher in the insulin group (6.70 mumol/gm) than in the control group (5.30 mumol/gm). Also, the mean adenosine triphosphate/diphosphate quotient (insulin group, 5.19; control group, 2.36) and the mean energy charge potential (insulin group, 0.919; control group, 0.851) were significantly (p less than 0.01) higher in the insulin group. It is concluded that the preventive application of high doses of insulin leads to an augmented myocardial adenosine triphosphate provision and a maintained cellular energy charge during coronary ischemia. As a result, ischemic tolerance is enhanced and myocardial protection is improved.

Adenine Nucleotides↗
PubMed1983

[Idiopathic enlargement of the right atrium].

In a 3 year old male patient with a very rare congenital enlargement of the right atrium the diagnosis was made only because of an occasional chest X-ray film. These dilated right atria rarely cause symptoms, but in rhythmic disorders or thrombosis they can be life threatening. The differential diagnoses of this entity are listed.

Arrhythmias, Cardiac↗
PubMed1982

[Surgery as handicraft, surgery as art, surgery as science (author's transl)].

The reputation of surgery is not only based on manual skill, though in the light of history the surgeon belonged rather to craft-gilds than to hippocratism. Not until the evolution of the whole medical science a new status of the surgeon was created. Today in a high degree he is a devoted servant to science, despite the priority of manual skill. An artist is praised for his brilliant abilities to manage problems by intuition, to improvise successfully, thus the surgeon can be designated as of congenial spirits. Examples describing the activities at the 2nd Surgical Clinic of the University of Vienna, illustrate these three virtues of surgery: manual skill, artistic work, scientific attitude. In this sense students as well as graduates should receive their education. In future the surgeon himself must guarantee by extreme personal engagement that this ideal conception of the surgical professional, criticising the methods of scholastic medicine, is maintained and can bear up against organization obstacles.

Animals↗
PubMed1982

Fibrin gluing in cardiovascular surgery.

Fibrin sealing represents a valuable addition to conventional techniques for stopping diffuse hemorrhage and for joining tissues. In some cases improved wound healing may be achieved. Without doubt the fibrin sealant is of great help to the cardiovascular surgeon, but it obviously does not replace an exact and subtle suturing technique.

Aorta↗
PubMed1982

[Exercise tolerance for indicating of aortocoronary bypass surgery (author's transl)].

In order to evaluate effects of aortocoronary bypass grafting on exercise tolerance, we analyzed the data of 109 patients who performed exercise tests before and one month or one year after surgery. Subgroups of patients were formed on the basis of preoperative exercise tolerance. Previously severely impaired patients benefited from surgery by an improvement of exercise capacity, whether preoperative left ventricular enddiastolic pressure at rest exceeded 16 mm Hg and left ventricular ejection fraction was below 50% or not. On the other hand, exercise capacity of patients who were comparable in respect to the numbers of coronary lesions and bypass grafts but whose exercise tolerance was less impaired preoperatively did not improve after surgery. Because in such patients, independent of coronary anatomy, surgery has been reported to be ineffective for prolongation of life, indication for aortocoronary bypass grafting in the presence of "good" exercise capacity must be questioned for symptomatic as well as for prognostic reasons.

Aged↗