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Biomedical subjects

F Unger

Publications and source records attributed to F Unger.

At least 19 recordsLinked to original sources
PubMed1992

Artificial blood and extracorporeal circulation (ECC).

To investigate a possible clinical use in ECC of artificial blood (AB) by means of a stroma free, polymerized and pyridoxylated hemoglobin a feasibility study was performed. Group I (5 calves) served as control. Group II (5 calves) received 2000 ml of a mixture of one part AB and one part Ringer's solution, group III (5 calves) 2000 ml of AB as priming solution. Blood samples were taken preoperatively, at 6 h, 24 h and then weekly up to 1 month. All animals survived and could be weaned from the ventilator immediately after the operation. Total hemoglobin was 10.6 before and 9.5 g/dl 12 h after the operation in mean in the group I and 11.5 and 11.9 for group II and III. Aortic mean pressure was increased in group II/III from preoperatively 105/95 mmHg to 124/135 mmHg after the end of cardio pulmonary bypass (CPB). The pulmonary vascular resistance increased in group II/III from 92/52 to 214/264 dyn*s*cm-5 in mean. This could not be observed in group I. Pulmonary resistance correlated with the concentration of free plasma hemoglobin.

Animals↗
PubMed1991

Early and late results following coronary bypass surgery beyond the age of 75 years.

The indication for coronary bypass surgery in the elderly has been dramatically expanded in recent years. The results, however, are often contradictory. 1,538 consecutive patients undergoing cardiac surgery were divided into two groups by their age at the time of operation: younger than 75 years (n = 1,480) and 75 years and older (n = 58). These groups were compared with regard to influencing factors of early and late mortality, morbidity, and quality of life. Preoperatively, the clinical condition of the group greater than or equal to 75 years was significantly worse than the condition of the group less than 75 years (NYHA IV: greater than or equal to 75 years: 63.8%; less than 75 years: 31.9%). Cerebrovascular diseases occurred more often in the patients greater than or equal to 75 years (stroke or transient ischemic attack: greater than or equal to 75 years: 8.6%; less than 75 years: 2.3%). The necessity of carotid reconstruction prior to coronary surgery was significantly higher in the patients greater than or equal to 75 years: (greater than or equal to 75 years: 5.2%; less than 75 years: 1.5%). Diabetes mellitus could be observed in 19.0% of the patients greater than or equal to 75 years and in 10.1% of the patients less than 75 years. The preoperative ejection fraction was similar in both groups. Cardiopulmonary bypass time and crossclamping time of the aorta did not differ significantly. Both groups received approximately the same number of distal coronary anastomoses. Rethoracotomy due to hemorrhage had been observed more often in the older group (greater than or equal to 75 years: 8.6%; less than 75 years: 4.5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1990

[Limiting factors in the use of the artificial heart].

The artificial heart (TAH) has become a clinical reality as a bridging device to staged transplantation. In order to manage one of the limiting factors of transplantation surgery, namely the lack of donor hearts, the use of TAH as a bridging device will be important for the next years. Nevertheless the development of TAH as a permanent prosthesis should be increasingly intensified. Biocompatibility must be the main goal of production. For the present there is no material in sight which fulfills all requirements. It might be possible though, that progresses in the development of synthetic materials will result in non-thrombotic TAH, herewith eliminating the vulnerable spot of TAH.

Biocompatible Materials↗
PubMed1989

Rupture of guide wire during percutaneous transluminal coronary angioplasty. Mechanics and management.

Two rare cases of rupture of the guide wire during percutaneous transluminal coronary angioplasty are described. Both patients required emergency surgical retrieval of the retained fragments and myocardial revascularization. The possible mechanics of the event and the options in the management are discussed with a review of the literature on this rare complication of percutaneous transluminal coronary angioplasty.

Angioplasty, Balloon↗
PubMed1989

Light and electronmicroscopic examination of calf lung tissue after left ventricular assisted circulation with the spindle pump.

The influence of the spindle pump, a nonpulsatile blood pump, used as LVAD on calf lung tissue was examined by means of the actual 16th protoype which was applied in 3 "acute" tests up to 13 hours of pumping duration and 8 prolonged experiments with pumping periods up to 63 hours. Samples were taken during the operation and after exitus of the test animal and investigated by light and electronmicroscopy. Histological findings of tissue changes could be ascribed to mechanical manipulations and shock-like influences. Regardless of the time of nonpulsatile perfusion this tissue damage remained within an acceptable range, indicating the absence of a deleterious effect of nonpulsatile flow.

Animals↗
PubMed1988

Artificial heart and cardiac transplantation: report on the first European combined procedure.

It became necessary to perform a staged procedure by means of total artificial heart followed by cardiac transplantation in a 26-year-old, female patient. The Ellipsoidheart, as an artificial heart, fitted excellently in the chest without compromising the surrounding structures. As soon as the patient recovered with the artificial heart, a consecutive transplantation was performed. This first European clinical experience gained confidence and suggests applying more artificial hearts as a bridge towards transplantation.

Adult↗
PubMed1988

Left heart assistance with the spindle pump.

The spindle pump--a new attempt at assisted circulation--was developed to prevent the main problems of nonpulsatile blood pumps, i.e. traumatic hemolysis, thrombus formation and sealing. It was essential to achieve adequate output with the lowest possible speed in order to minimize traumatic hemolysis. The result was a spindle pump with three windings in a U-shaped housing driven by an electric motor. Many tests were necessary to establish a prototype. The spindle was completely redesigned several times to reach an acceptable volume output and corresponding pressure output. In animal experiments this final prototype working as a LVAD, with a speed of 5400 RPM circulates 4 liters/min against BP of 110 mmHg. The hemolysis rate has been low in acute and survival experiments (27 hours up to now), and is between 25 and 30 mg/100 ml of free hemoglobin, thus within the normal range.

Animals↗
PubMed1985

[Surgical therapy of coronary disease: aortocoronary bypass. Risks and complications].

The aorto-coronary bypass surgery is a well established method for treating patients with coronary artery disease. In the last five years at the University Clinic in Innsbruck 417 operations have been performed. The operation letality decreased down to 0.66%, whereby the mean revascularisation rate increased to 2.8. The specific aim of this paper is to show the benefits and the risks of this operation to validate and to verify the benefits in regard to the risks, which could be kept very low.

Adult↗
PubMed1985

Orthotopic heart replacement by nonpulsatile axial blood pumps.

In the last decade, there have been many experiments with nonpulsatile blood pumps to perform functional heart replacement by biventricular assist devices. To determine if life is sustainable with nonpulsatile blood flow, two nonpulsatile blood pumps were implanted in the orthotopic position as an artificial heart after removal of the natural heart in extracorporeal circulation. In three preliminary experiments, the feasibility of total heart replacement with nonpulsatile implantable blood pumps was shown.

Animals↗
PubMed1985

Hydraulic driving unit and control system for artificial hearts.

A driving unit for artificial ventricles was constructed in which the power transmission is hydraulic. This avoids the danger of an air embolism, which is characteristic of pneumatic drives in the case of membrane rupture. An electromagnet as a power source drives a rolling membrane pump to move the transmission fluid to the artificial ventricle. This incompressible connection allows direct control of membrane motion and pumped blood volume simply by measuring the armature stroke. The volume-controlled mode is characterized by automatic self-regulation according to Starling's law and self-synchronization when the drive is used as a left (or right) ventricular assist device. Several measures were taken to increase the operational safety. The hemodynamic efficiency of the drive was tested in a number of in vivo experiments. The long-term stability was proven in a 12-month durability test.

Animals↗