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Biomedical subjects

B Aberg

Publications and source records attributed to B Aberg.

At least 55 records · Page 3Linked to original sources
PubMed1987

Massive hematemesis due to an aorto-oesophageal fistula. Case report.

A patient with massive hematemesis due to an aorto-oesophageal fistula is presented. An aorto-oesophageal fistula is mostly a fatal disease. In the literature it is pointed out that recognition of the clinical syndrome with midthoracic pain, massive arterial hemorrhage and exsanguination after a symptom-free interval might ameliorate the prognosis. In the reported patient the correct diagnosis was not immediately suspected. The patient, however, survived a long operation and exsanguination without any major postoperative complications or sequelae.

Aortic Diseases↗
PubMed1985

Diagnostic considerations of tongue-base malignancies.

Forty-two patients with malignancies localized to the base of the tongue were treated at Sahlgrenska Hospital between 1971 and 1980. These patients were re-analyzed with respect to symptomatology and clinical outcome. Pain in the mouth, throat, and ears as well as swallowing difficulties were the most frequent overt symptoms of disease. In general, patients experienced symptoms for at least 3 months before a positive tumor diagnosis was made. In all, 75% of the patients were found to have large tumors which extended beyond the base of the tongue. Most of the patients were treated with irradiation. The overall 3-year survival rate was 28%, while individual patient survival was related to the size of the primary tumor and to the occurrence of lymph node metastases. Careful attention to symptomatology may reduce delays in establishing an accurate diagnosis and consequently improve the prognosis for patients with these cancers.

Adult↗
PubMed1985

Delayed left ventricular free wall rupture complicating coronary artery bypass surgery. A case report.

Rupture of the left ventricular free wall is a not uncommon life-threatening complication of acute myocardial infarction and after prosthetic mitral valve replacement. To our knowledge, no case of left ventricular rupture after coronary artery bypass surgery has been reported. A case is now described in which coronary artery bypass grafting was complicated by delayed rupture, which was successfully repaired. Different etiologic factors are discussed, but the cause considered most likely was trauma from elevation of and traction on the heart in exposure of its posterior aspect.

Coronary Artery Bypass↗
PubMed1984

Ear drum mobility and middle ear volume measured with tympanometry.

Tympanometry was evaluated as a measure of the volume of the air-containing space of the middle ear cleft as well as of tympanic membrane displacement in persons with intact tympanic membranes. Static compliance reduced with compliance of ear canal volume at -400 mm H2O, was determined with 0.22 kHz probe tone frequency. Further the difference in compliance obtained at +/- 400 mm H2O was regarded as a measure of ear drum mobility. The volume of the middle ear cleft including the mastoid air cell system was measured indirectly by X-ray of the ear in a lateral projection. No relation was found to exist between static compliance and mastoid air cell area measured on the X-ray film. Nor was there any relation found between ear drum mobility measured with tympanometry and size of the mastoid air cell system.

Acoustic Impedance Tests↗
PubMed1983

Surgical repair of aortico-left ventricular tunnel in a 7-day-old child.

A 7-day-old girl was successfully operated on for aortico--left ventricular tunnel. She seems to have been the youngest patient with successful repair of the malformation. The case was the second of its type operated on at the Karolinska Hospital. Severe congestive heart failure is usually an early occurrence in aortico--left ventricular tunnel. The high mortality rate without operation illustrates the importance of early diagnosis and surgery. A patch closure technique is recommended as permitting optimum function of the aortic valve.

Aorta↗
PubMed1981

Flow resistance of the interlobular artery in the rat kidney.

The afferent and efferent arterioles are considered to be the most important resistance vessels within the renal vasculature, but there are indications that a pressure drop occurs along the interlobular artery. This pressure drop was investigated from two aspects: 1) In rat kidneys the "stop-flow pressure" in the efferent arterioles was measured with the micropuncture technique. At arterial pressures between 100 and 130 mmHg the stop-flow pressure did not exceed 85 mmHg, which means that the highest pressure at the end of the interlobular artery was 85 mmHg; 2) A mathematical model was constructed, assuming that the diameter of the interlobular artery decreased stepwise from 60 to 10 micrometers. The artery was divided into 20 segments, each segment containing one afferent arteriole. The flow in the afferent arterioles increased linearly from 100 nl . min-1 in the first segment to 130 nl . min-1 in the last segment. When the pressure in the first segment was 120 mmHg, it was calculated that the pressure in the last segment was 85 mmHg. These findings strengthen the theory that the interlobular artery may participate in the regulation of the intracortical blood flow in the rat kidney. We conclude that the afferent arteriole of the most superficial nephron is nearly maximally dilated and that the juxtamedullary nephron is able to either dilate or constrict its arteriole in normotensive and normohydrated rats.

Animals↗
PubMed1981

Haemodynamic evaluation of the convexo-concave Björk-Shiley prosthesis in patients with narrow aortic annulus.

A late haemodynamic re-evaluation at rest and during exercise was performed in 22 patients with isolated aortic valvular disease and narrow aortic annulus, operated upon with the convexo-concave Björk-Shiley prosthesis. The 21 mm prosthesis had been inserted in 11 patients and the 23 mm one in the other 11 patients. Left ventricular pump function improved and was normalized in half of the patients. The mean systolic pressure difference across the 21 mm convexo-concave prosthesis was 16.2 +/- 8.1 mmHg at rest and 20.7 +/- 7.9 mmHg during exercise (32 +/- 10 watts). It was 14.9 +/- 6.0 mmHg at rest and 18.6 +/- 6.3 mmHg during exercise (34 +/- 156 watts) across the 23 mm convexo-concave prosthesis. Compared with the earlier investigated standard model Björk-Shiley prosthesis, the 21 mm convexo-concave version creates a lower resistance to blood flow (less than 0.01), whereas no such difference could be demonstrated in the two models of 23 mm tissue diameter. It was concluded that the new convexo-concave tilting disc valve constitutes an improvement over the standard model in the management of the narrow aortic annulus permitting insertion of a 21 mm prosthesis.

Adult↗
PubMed1981

Early results after combined aortic and mitral valve replacement with the convexo-concave Björk-Shiley prosthesis.

This paper reports the early results of combined aortic and mitral valve replacement in 39 patients, who underwent operation with the convexo-concave Björk-Shiley prosthesis. There were no intra-operative deaths. Two patients (5%) died while in hospital of myocardial failure and left ventricular rupture, respectively. One late death (3%) was due to a thrombosis of the mitral prosthesis (N.Y.H.A. class IV at operation). Cumulative follow-up (2-31 months) was 100%. One patient had radial artery embolization while converting to atrial fibrillation. Another patient required repair of an aortic paraprosthetic leakage. Clinical improvement (N.Y.H.A.) was noted in 15/19 re-examined patients (79%). Average heart volume decreased (p less than 0.05) and Maximal working capacity increased (p less than 0.05) after valve replacement. Seven patients (7/19) converted to sinus rhythm after operations and one (1/19) developed atrial arrhythmia. Haemolysis was generally mild and without signs of anaemia. The overall thrombo-embolic rate (5.9% per year) remained thus far the same as that encountered with the standard model prosthesis in combined aortic and mitral valvular disease.

Adolescent↗
PubMed1980

Central haemodynamics at rest and during exercise before and after combined aortic and mitral valve replacement with the Björk-Shiley tilting disc valve prosthesis.

Pre- and postoperative haemodynamics were compared in 36 patients with combined aortic and mitral valvular disease. These patients suffered from markedly restricted cardiac function in terms of cardiomegaly, low physical working capacity, hypokinetic central circulation and pulmonary hypertension. Valve replacement was performed with the Björk-Shiley Delrin disc (10) and pyrolytic carbon disc (26) prostheses and followed by subjective improvement in the majority of patients. Heart volume decreased and working capacity increased in average significantly, but were not restored to normal. The main response to surgery was a shift towards a normokinetic circulation, although many patients remained hypokinetic. There was also regression of pulmonary hypertension as a result of reduced left atrial pressure and pulmonary vascular resistance. In spite of a significant decrease in left atrial mean pressure, it remained elevated with prominent v-waves in many patients, particularly during exercise. Marked v-waves in the right atrial pressure curves were also noted in one third of the patients. Only one patient, however, suffered from clinically manifested tricuspid incompetence. This study shows the benefits of combined aortic and mitral valve replacement, even in patients with longterm haemodynamic burden on the myocardium. Although the central haemodynamics were almost normalized at rest, abnormal responses persisted during exercise.

Adult↗
PubMed1979

Comparison between the in vitro flow dynamics of the standard and the convexo-concave Björk-Shiley tilting disc valve prostheses.

In the new convexo-concave model of the Björk-Shiley prosthesis the disc pivots 2.5 mm downstream, creating a space between the disc and the ring when the disc tilts open. Its flow dynamics were compared with those of the standard model under steady flow rates 0--32 1/min of a water-glycerin mixture employed as blood-analogous test fluid. The following results are valid for corresponding sizes of the conventionally used 21, 23, 25, 27, 29 and 31 mm prosthetic valves of the two models. The transprosthetic pressure fall varied directly, but in a parabolic fashion with the steady flow rate for all the partial and full flow orifices. The resistance to flow 0--32 1/min for the full flow orifice of the convexo-concave prosthesis was in average 16% lower than that of the standard model, with highly significant differences for the 21 and 23 mm prostheses (p less than 0.001). There was a redistribution of flow towards the smaller prosthetic opening from 23% (S.D. +/- 1.4) for the standard model to 30% (S.D. +/- 2.4) for the convexo-concave model (p less than 0.001). The minimum steady flow rate required to maintain the convexo-concave disc in completely open position (60 ml/sec) was only half that (37--50%) required for the standard disc (125 ml/sec) (p less than 0.001). Regurgitation through the closed prosthesis varied directly and linearly with the driving pressure and was slightly but definitely lower with the convexo-concave model than with standard model. The main features of the new design are decreased resistance to flow, redistribution of the flow within the prosthesis in order to prevent stasis along its smaller orifice, diminished opening resistance and reduced regurgitation. It is concluded that the flow dynamics of the convexo-concave model Björk-Shiley prosthesis constitute a significant improvement over those of the standard model.

Biomechanical Phenomena↗
PubMed1977

Combined aortic and mitral valve replacement with the Björk-Shiley tilting disc valve prosthesis. Early and late results in 75 consecutive patients.

This study evaluates the early and late results of combined aortic and mitral valve replacement with the Björk-Shiley tilting disc valve prosthesis in 75 consecutive patients operated upon during a 6-year-period commencing October 1969. The Delrin disc model Björk-Shiley prosthesis was inserted in the first 20 patients and the pyrolytic carbon disc model in the remainder. The opening angle was increased from 50 degrees to 60 degress and the Teflon sewing ring was designed with two flanges in the pyrolytic carbon disc mitral model. The patient material was characterized by marked cardiomegaly, impaired physical working capacity, hypokinetic central circulation, pulmonary hypertension and a 59% incidence of atrial arrhythmias before operation. Surgery was performed during generalized hypothermia to 30 degrees C and selective coronary perfusion, and the mitral valve was always replaced first. There were no intra-operative deaths, although 7/75 patients (9%) died while in hospital. Twelve patients (16%) died in average 19 (2-59) months postoperatively. Thrombo-embolic complications, which were frequently associated with poor anticoagulation, occurred in 9 patients and were fatal in 4 cases, corresponding to an incidence per patient month of 0.005 and 0.002, respecitvely. This risk was not affected by the type of prosthesis. One patient required operative repair of an aortic paraprosthetic leakage. Clinical improvement was found in 88% of the long-term survivors. The maximal working capacity increased in average 41% over the pre-operative value (p less than 0.001) and cardiac enlargement diminished in average by 22% (p less than 0.001). The incidence of atrial arrhythmias decreased slightly to 48%. Haemolysis was mild and without clinical significance. The actuarial curve indicated a 75% survival rate 3 years after operation.

Adolescent↗
PubMed1975

A theoretical study of restricted convection-diffusion as applied to blood-tissue barrier exchange.

This paper handles a model of the capillary function in the exchange of uncharged molecules between the blood and the tissue. The capillary system is subdivided into a filtering and a reabsorbing part. The exchange is assumed to occur through channels which are described in operational terms as pores. Through these pores there is a transport of solutes by concomitantly acting convection and diffusion influenced by a steric hinderance (restricted convection-diffusion). The outflux of glucose and raffinose is enhanced in the filtering pores, raffinose relatively more than glucose. In the reabsorbing pores the outward diffusion is hindered to some extent, raffinose relatively more than glucose. It is shown that the net effect of filtration and reabsorption is to increase the outflux of raffinose as compared to that of glucose. This mechanism may explain why glucose and raffinose and other small molecules appear to pass across capillary walls in proportion to their free diffusion coefficients and not in proportion to their restricted diffusion coefficients.

Biological Transport, Active↗
PubMed1975

The effect of restricted convection-diffusion on bolus concentration along an exchange vessel.

If a sudden rise in solute concentration travels through a capillary system, a diffusible neutral solute passes the walls of the exchange vessels. If then the rate of passage depends on a chemical potential gradient (diffusion) and a hydrodynamical potential gradient (convection) and is sterically restricted (restricted convection-diffusion), water and low molecular weight solvents leave the filtering part of the capillary at a higher rate than the solute, causing a relative increase in its concentration. This phenomenon and the effect of an increasing pore size along the capillary is investigated in a model for an impermeable solute and two diffusible solutes, corresponding to glucose and raffinose. It is shown that in the model, the concentration fall along the capillary tends to become rectilinear.

Animals↗