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Biomedical subjects

B K Semb

Publications and source records attributed to B K Semb.

At least 37 records · Page 2Linked to original sources
PubMed1984

Should the lungs be ventilated during cardiopulmonary bypass? Clinical, hemodynamic, and metabolic changes in patients undergoing elective coronary artery surgery.

No beneficial effects were achieved by ventilating the lungs of a group of 10 patients during total extracorporeal circulation for coronary artery bypass operation. Ventilation of nonperfused lungs, which was suggested to prevent postoperative atelectasis, may even have negative effects. Intrapulmonary shunting increased significantly (p less than 0.05), while the shunt fraction in the nonventilated lungs of another group of 10 patients remained unchanged. There were only minor differences between the two groups with respect to systemic and pulmonary hemodynamic changes.

Cardiopulmonary Bypass↗
PubMed1984

Flail tricuspid leaflet in childhood--a possible cause of supraventricular tachycardia.

The echocardiographic features of flail tricuspid leaflet of unknown aetiology is reported. The diagnosis was made in a previously healthy 11 year old boy presenting with recurrent attacks of supraventricular tachycardia. M-mode echocardiography showed rapid early systolic movement of the tricuspid valve away from the transducer and holosystolic, coarse fluttering of its small, redundant part. The sector scan, showing the free movement of a part of the septal tricuspid leaflet into the right atrium during systole was confirmatory. It was felt that Ebsteins anomaly could be excluded. The recurrent attacks of supraventricular tachycardia were difficult to treat pharmacologically, and may have been related to the flail tricuspid leaflet which mechanically triggered the arrhythmia through an aberrant pathway.

Bundle-Branch Block↗
PubMed1984

Echocardiographic evaluation of atrial function after Senning and Mustard correction for transposition of the great arteries.

Two groups of six children who had undergone either Senning or Mustard repair for uncomplicated transposition of the great arteries were studied with M mode echocardiography derived from a phased array sector scanner picture. The newly created atria were visualised from the subxiphoid region and the upper systemic venous inflow was selected for a simultaneous M mode registration with a subsequent wall motion analysis with a commercially available computer. In the Mustard group of patients the atrial walls seemed to move passively with the overall heart movements, while abrupt atrial wall excursions of both atria synchronous with heart action were noted in all patients after Senning repair. In this group also slow cyclic changes followed respiration. The atrial wall movements were significantly superior (p = 0.001) in the Senning group of patients. It is concluded that, in contrast to the Mustard method, the Senning operation seems to lead to a viable atrium with the capability of increasing and diminishing atrial diameter and with subsequent potential for growth.

Adolescent↗
PubMed1984

A modified nonpulsatile flow system for the in vitro study of cardiac valve prostheses.

An in vitro system was constructed for measurements of resistance to forward flow by cardiac valve prostheses at a wide spectrum of flow rates. There was a close correlation between the known area of constriction (valvular orifice) and that calculated from the flow/pressure relationship using derivations of the Bernoulli equation. This simple setup appears particularly suited to determine hydrodynamic efficiency of various cardiac valve concepts on a comparative basis.

Heart Valve Prosthesis↗
PubMed1984

In vitro hydrodynamic performance of various cardiac prosthetic valves tested in a modified nonpulsatile flow system.

Hydrodynamic studies were performed in a modified nonpulsatile flow system to compare the efficiency of various prosthetic cardiac valves in vitro. Apart from direct flow/pressure relations across the valves the effective orifice area available for forward flow was determined by derivations of the Bernoulli hydrodynamic equation. By defining the relationship between calculated effective orifice area and known orifice area of the valves a more precise appraisal of the hydrodynamic characteristics of the various valve designs was possible.

Heart Valve Prosthesis↗
PubMed1984

Effect of CO2 on peripheral flow and central hemodynamics.

A variable pattern of organ flow distribution was observed during experimental hypo- and hypercarbia. Mainly two patterns of organ flow changes emerged in that hepatic, renal and skeletal muscle flow showed a decreasing tendency during hypercarbia while gastrointestinal, myocardial and cerebral flow increased during hypercarbia and decreased during hypocarbia. These changes were accompanied by typical central hemodynamic changes including a decrease in systemic and pulmonary vascular resistance during both hypocarbia and hypercarbia which was also accompanied by decreased myocardial contractility.

Animals↗
PubMed1984

Surgical considerations in the treatment of cardiac myxoma.

Misinterpretation of confusing cardiac, constitutional, and embolic symptoms delayed the diagnosis of cardiac myxoma and caused two of 18 patients to undergo acute operations during cardiogenic shock with pulmonary edema. In recent cases echocardiographic screening of unclear cardiac symptoms gave the correct diagnosis early. Despite the simple surgical procedure (excision of tumor and underlying endocardium), the postoperative course was complicated by cardiac failure, arrhythmias, and systemic reactions. Prosthetic valve thrombosis and malignancy caused two early deaths. Two patients died later of cerebrovascular insults. Both belonged to a group of five patients having preoperative emboli from fragile myxomas. Four of these five had coronary or cerebral myxomatous pseudoaneurysms. A 6 year follow-up, including recatheterization, showed no tumor recurrence and generally normalization of the clinical condition, heart size, and catheterization findings. Even pronounced mitral insufficiency accompanying left atrial myxomas had subsided spontaneously. Tricuspid insufficiency in two patients with right atrial myxomas persisted, necessitating reoperation in one. When diagnosed, a cardiac myxoma should be removed promptly to reduce cardiac and embolic complications, including myxomatous pseudoaneurysm formation, which might be more frequent than previously recognized.

Female↗
PubMed1983

A 5-year follow-up of the Medtronic-Hall valve: survival and thromboembolism.

Throughout the period 1977 to 1982, 436 patients underwent aortic valve replacement (AVR), 106 underwent mitral valve replacement (MVR) and 56 patients underwent double valve replacement (DVR), with the Medtronic-Hall prosthetic valve (previous equivalent: Hall-Kaster valve). Early and late mortality were 4% and 9% for AVR, 8% and 11% for the MVR and 7% and 13% in the DVR, respectively. Actuarial survival after 5 years of follow-up was 80.9% for AVR, 75.4% for MVR and 81.0% for the DVR. Thromboembolic complications included 2 cases of valve thrombosis in the AVR, in one case secondary to valve endocarditis. Eleven further thromboembolic episodes occurred in 10 patients with AVR. In MVR an aspergillus thrombus was found on the valve at autopsy in a patient dying from multiple cerebral aspergillus abscesses. Five further thromboembolic episodes occurred in 4 patients with MVR. In the DVR group there was one valve thrombosis and one further patient with a thromboembolic episode. The actuarial probability of remaining free from thromboembolism at the end of the 5 years of follow-up was 92.5% for AVR and 83.7% for MVR.

Aortic Valve↗
PubMed1983

Intravenous infusion of vasopressin in the treatment of bleeding from severe hemorrhagic gastritis.

Over a 3-year period continuous intravenous infusion of moderate doses of vasopressin in 13 patients bleeding profusely from hemorrhagic gastritis, was associated with rapid control of the bleeding in 11 patients, while in 2 patients prolonged infusion was required to stop the hemorrhage. In 2 patients there was a relapse of the hemorrhage 3 and 7 days after the initial treatment, which was successfully controlled by renewed vasopressin infusion. There was no mortality and no complications of the vasopressin treatment were encountered. The results compared favourably with the experience from the preceding 3-year period where a comparable group of patients undergoing conventional medical and surgical treatment suffered a mortality of 38%. This study therefore suggests that vasopressin infusion performed continuously with moderate doses over extended periods, improves survival of patients with severe hemorrhagic gastritis through control of bleeding.

Adult↗
PubMed1982

The effect of catecholamines on gastric mucosal flow.

The effect of intravenous administration of adrenaline, noradrenaline, and isoprenaline on gastric mucosal flow, measured by hydrogen clearance techniques, showed that small doses of adrenaline induced slight mucosal vasodilatation in anaesthetized cats. In both anaesthetized and conscious animals both noradrenaline and large doses of adrenaline produced mucosal vasoconstriction, whereas isoprenaline increased gastric mucosal flow. Similar effects were observed in acute experiments after vagotomy. In the awake animal noradrenaline, adrenaline, and isoprenaline depressed pentagastrin-stimulated acid secretion.

Anesthesia, General↗
PubMed1982

Regional gastric flow changes after meal stimulation measured by the hydrogen clearance technique in conscious cats.

Regional gastric mucosal flow changes were studied, after meal stimulation, with hydrogen clearance techniques in conscious cats. Generally, a substantial initial increase of corpus mucosal flow was accompanied by a moderate decrease of antral mucosal flow. These changes were reversed at the end of the secretory phase. Autoregulation of gastric flow, with the potential of regional flow increase in areas of augmented metabolic activity, is suggested as a possible explanation of the pattern of antral/corpus mucosal flow shifts accompanying physiological gastric secretory stimulation.

Animals↗
PubMed1982

Effect of vasopressin on canine gastric mucosal circulation.

Continuous intravenous infusion of small doses of vasopressin (0.05 microgram/kg/h) in anaesthetized dogs was effective in reducing gastric mucosal flow, whereas moderate doses (0.2 micrograms/kg/h) induced a substantial flow reduction. Larger doses of vasopressin (2-4 micrograms/kg/h) precipitated massive gastric flow reduction with subsequent hyperaemia, which was not effectively controlled by moderate vasopressin doses. The effect of intraportal infusion of vasopressin on mucosal flow was similar to that of intravenous infusion. Prolonged intravenous infusion of moderate vasopressin doses maintained mucosal flow reduction over extended periods. The implications of the findings are discussed with particular reference to clinical use of vasopressin as a means of controlling bleeding from gastric mucosal lesions in patients.

Animals↗
PubMed1982

Effect of pentagastrin on regional gastric blood flow in conscious cats.

Total gastric flow studies indicated that a transient, considerable flow increase was followed by a more moderate increase of total gastric flow during pentagastrin stimulation in anesthetized cats. In conscious cats regional gastric flow studies, using hydrogen clearance techniques, suggested that raised flow to the corpus region during the stimulation period was accompanied by a moderate decrease of antral flow.

Anesthesia↗
PubMed1981

Changes of regional gastric flow measured by hydrogen clearance techniques after histamine stimulation in conscious animals.

Gastric microcirculatory changes were studied by means of hydrogen clearance techniques in conscious cats during histamine stimulation. A considerable increase of corpus mucosa flow occurred, whereas a less substantial increase of antrum mucosa flow was observed during stimulation with histamine at 2 micrograms/kg/min, intravenously. Stepwise increase of infused histamine was accompanied by a gradual increase of corpus flow in the mucosa, which during supramaximal stimulation decreased slightly but still remained considerably elevated above control values. A similar decrease of antral mucosa flow occurred earlier during maximal stimulation, suggesting shunting of blood from the antrum to the corpus region. Total gastric flow measurements performed in anesthetized animals similarly showed decreased flow at a rate of histamine infusion which produced supramaximal stimulation in the conscious animals. However, total gastric flow remained elevated also during this stage compared with prestimulation values. A hypothesis of a dual effect of histamine on the gastric circulation is suggested, including regulation of flow through generalized vasodilatation and increased metabolic activity in the parietal cell mass.

Animals↗
PubMed1981

Tricuspid atresia corrected with valved xenograft conduits.

In eight patients from 1976 until 1980, tricuspid atresia (TA) was corrected with valved xenograft conduits between either the right atrium and the main pulmonary artery or between the right atrium and the rudimentary right ventricle. All patients suffered from transient right-heart failure postoperatively and eventually developed normalized cardiac function throughout the first two months after operation. At recatheterization one year postoperatively, the right atrial pressure had generally only increased slightly, the pulmonary artery pressure was normal in all patients and only minor pressure differences were present across the valved conduits. X-ray examination showed normalization of the heart size in the majority of the patients, and in those with conduits between the right atrium and the right ventricle a considerable enlargement of the right ventricular chamber together with normalization of right ventricular contractility had developed. Arterial oxygen saturation, haemoglobin and haematocrit valves had normalized in all patients. One patient died postoperatively of intractable right ventricular failure, septicaemia and intravascular coagulation, and another was uneventfully re-operated on two years postoperatively because of conduit thrombosis. Clinical results were gratifying. Two patients with valved conduits between the right atrium and the right ventricle showed a normal unrestricted level of activity without medication, while patients with valved conduits between the right atrium and the main pulmonary artery were digitalized with an almost normal level of activity. Early repair with valved conduits of patients with TA is advocated.

Angiography↗