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Biomedical subjects

R Cronestrand

Publications and source records attributed to R Cronestrand.

At least 19 recordsLinked to original sources
PubMed1986

Staged thrombendarterectomy for bilateral ileofemoral arteriosclerosis. An alternative approach.

Bilateral ileofemoral obstruction is usually treated by either a transabdominal reconstruction or an axillobifemoral bypass graft. In this report an alternative approach is presented. Twenty-one patients underwent staged bilateral retroperitoneal thrombendarterectomy. In 14 limbs a concomitant femoropopliteal bypass graft was performed. There was no operative mortality, and morbidity rates were low. The only ileofemoral occlusion occurred after 68 months for 5-year and 6-year patency rates of 100% and 93.8% respectively. In addition, 2 femoropopliteal grafts thrombosed, leaving however, the ileofemoral reconstructions patent. These encouraging results make this two-staged approach an attractive alternative to conventional major transperitoneal operations or axillobifemoral bypass grafts with their poor long-term patency rates.

Adult↗
PubMed1984

Human renal allograft blood flow, oxygen extraction, and prostaglandin release: their bearing on graft function.

The intraoperative blood flow, oxygen extraction, and prostaglandin production were studied in 26 transplanted kidneys. Eleven were from related donors and 15 from cadavers. Postoperative dialysis was required by four of the five recipients of a cadaveric kidney having an intraoperative blood flow of less than 200 ml/min/100 gm of tissue. All the cadaveric kidneys with a blood flow greater than this produced urine immediately after revascularization. The blood flow in the cadaveric kidneys was related to the total ischemia time, with a lower rate in kidneys preserved for more than 24 hours. There was no difference in the oxygen extraction values for the kidneys in the related donors, in their associated recipients, and in the cadaveric organ recipients. During postoperative catheterization of the renal vein the oxygen extraction for the kidneys from related donors was practically normalized, while for the cadaveric kidneys it was increased though still subnormal. This difference was also reflected in the renal function at that time. No evidence was found that prostaglandins are involved in the regulation of the blood flow to the graft kidney.

Adolescent↗
PubMed1983

Biosynthesis of prostaglandins in microsomes of human skeletal muscle and kidney.

The capacity of human skeletal muscle, renal cortical and renal medullary microsomes to synthesize prostaglandins (PGs) from exogenous precursor was investigated. The microsomal fractions were incubated with [1-14C]-labelled arachidonate ([14C]-AA) in the absence and in the presence of reduced glutathione (GSH). [14C]-PGs formed in the incubates were extracted, separated by thin-layer chromatography and quantified using liquid scintillation spectrometry. [14C]-labelled PGE2, PGF2 alpha and 6-keto-PGF1 alpha were found to be the principal products of microsomal PG formation and appeared in similar relative quantities in the incubates of all three tissues studied. In some incubates of renal cortical and renal medullary microsomes formation of smaller relative amounts of [14C]-PGD2 and thromboxane B2 was also noted. In addition, formation of substantial amounts of a polar, not yet identified compound was frequently observed in all incubates. In the absence of GSH, [14C]-6-keto-PGF1 alpha was the main PG formed by microsomes of all of the three tissues. At the expense of 6-keto-PGF, the addition of GSH resulted in an almost 2-fold stimulation of [14C]-PGF2 alpha formation in the skeletal muscle and renal cortical incubates, whereas in the renal medullary incubates an increase in the relative amounts of [14C]-PGE2 was observed. The PG synthetic capacity was highest in the skeletal muscle and lowest in the renal cortical microsomes. The results demonstrate a considerable capacity of human skeletal muscle and of the renal cortex and renal medulla to synthesize prostacyclin. Furthermore, the data reveal GSH-dependent differences in the expression of PG biosynthesis in these tissues. The GSH-dependent differentiation of PG synthesis may reflect a mechanism of adaptation of local PG production to the physiological processes.

Aged↗
PubMed1982

Intra-operative variations in carotid artery blood flow and cardiac output: the effects of changes in blood volume and carbon dioxide during surgery under neurolept anesthesia.

Seven patients were operated on for stenosis of the internal carotid artery (ICA) with endarterectomy under neurolept anesthesia. The ICA blood flow was found to be unchanged after reconstruction following an operative blood loss of one fifth of the patient's blood volume despite variations in cardiac output. The relationship between carbon dioxide tension and cerebral blood flow remained unchanged during hypovolemia. It is concluded that the autoregulation of the cerebral blood flow is maintained under neurolept anesthesia.

Aged↗
PubMed1981

Central haemodynamics during halothane and enflurane anaesthesia in vascular surgery.

Central haemodynamics were studied before and during reconstructive vascular surgery in 18 patients receiving halothane or enflurane anaesthesia (nine patients in each group). In both groups cardiac output (CO), stroke volume (SV), oxygen uptake (VO2) and arterial blood pressure fell significantly after induction of anaesthesia, whereas the arterio-venous oxygen difference (AVD) and the total peripheral resistance (TPR) remained unchanged. In spite of an average intraoperative blood loss of 600 ml, which had not been substituted for, surgery brought about an increase in CO, SV and VO2, while the AVD and TPR remained unchanged. Following transfusion of 900 ml of blood, CO and SV showed a further significant increase in both groups, whereas VO2 was unchanged and the AVD and TPR fell significantly. The pulmonary capillary venous pressure (PPCV) was stable during induction of anaesthesia and surgery but increased after blood transfusion. The changes in SV and PPCV were analyzed in relation to the concept of ventricular function curves. It is concluded that there were no fundamental differences in central haemodynamics between halothane and enflurane anaesthesia either before or during surgery. In both groups the changes in CO and SV were due mainly to a reduced demand of oxygen transport and expected changes in sympatho-adrenergic tone rather than to myocardial depression.

Aged↗
PubMed1981

Subcellular binding of 99Tcm-gluconate in infarcted myocardium in dogs.

Binding of 99Tcm-gluconate on the subcellular level in myocardial infarct tissue in the dog was investigated by means of a fractionated centrifugation technique. High isotope activity/g protein was recorded in the mitochondrial fraction indicating the 99Tcm-gluconate binds preferentially to a protein structure localized in the mitochondria.

Animals↗
PubMed1981

Leg haemodynamics during different forms of anaesthesia in patients undergoing reconstructive vascular surgery.

In the present study the effects of three different anaesthetics (halothane, n = 9, enflurane, n = 9, and neurolept, n = 11) on leg circulation were studied during vascular reconstruction with a reversed femoropopliteal saphenous vein bypass graft. Leg vascular resistance showed significant differences between the three anaesthetic groups. Thus, during the pretransfusion period, leg resistance in the neurolept group was significantly higher than in the halothane and enflurane groups, although the blood volume did not differ significantly between the groups. Though leg resistance after blood transfusion decreased significantly more in the neurolept group compared with the two other groups, the resistance after transfusion was still significantly higher in the neurolept group. Inducing pharmacological vasodilatation caused significant increases in common femoral arterial and bypass blood flows in all groups, but the increases were significantly more pronounced in the neurolept group. It is concluded that leg haemodynamics are influenced in different ways according to the anaesthetic agents used. This, in turn, might contribute to a better understanding and a more correct interpretation of the results of intraoperative flow and pressure measurements, and, consequently, to improvement of the reconstructive procedure.

Aged↗
PubMed1980

Factors determining outcome of reversed saphenous vein femoropopliteal bypass grafts.

The investigation was designed to study factors that might be of predictive value in femoropopliteal vein bypass grafting. A series of 146 grafts had a cumulative 5-year graft patency of 82.5 per cent. Five-year limb survival rate in salvage cases was 77.9 per cent. These results are encouraging. However, taking certain factors into account, the patency rates varied. In limbs with claudication, the 5-year graft patency rate was significantly higher than in salvage procedures (P < 0.05). Basal and maximal (during pharmacological vasodilatation) intraoperative graft flow rates were also significantly higher in claudicating limbs (P < 0.01). Reconstructions in limbs with a good run-off had better patency and flow rates than in limbs with a poor run-off (P < 0.001). This suggests that progression of distal atherosclerosis is a major factor for late graft thrombosis. The incidence of graft thrombosis was correlated with the flow rates (P < 0.01). Age, the presence of diabetes, graft diameter and the site of the distal anastomosis did not affect patency.

Adult↗
PubMed1980

Blood inflow and coagulation in vascular catheters. Comparison of the effect of polysaccharide solutions, saline and contrast medium.

Inflow of blood into intraarterial catheters in dogs following single and continuous injections of saline, contrast medium and polysaccharide fluids were analysed with special reference to the influence of their density and viscosity. Clot formation was also analysed and the favourable properties of one variant of the polysaccharide fluids were demonstrated.

Animals↗
PubMed1980

The advantages of the great saphenous vein as a femoropopliteal graft. A report on its clinical use.

As a majority of vascular surgeons prefer the autologous saphenous vein as a bypass graft below the inguinal ligament, the need of alternative graft materials or reconstructive techniques is confined to patients with unavailable or unsuitable saphenous veins. The aim of this investigation was to ascertain how often these alternative procedures are necessary. From 1973 to June 1979, the great saphenous vein was used as a femoropopliteal graft without regard to fixed limitations in the diameter and the quality of the vein. During this period, vascular reconstruction was required in 148 limbs due to symptomatic atherosclerotic occlusion of the superficial femoral artery. In 144 of these cases, the ipsilateral (138) or the contralateral (6) great saphenous vein was used for a femoropopliteal bypass reconstruction. Thus, the vein could not be utilized in only 4 of 148 cases (2.7%). As graft patency rate was not subject to the size and quality of the vein and as cumulative patency rates in the 144 grafts were most satisfactory (97.9, 92.0 and 81.9% at 1 month, 1 year and 5 years, respectively), although all these veins were used regardless of their calibre and quality, we conclude that the great saphenous vein can be used more liberally as a graft for femoropopliteal occlusion. In approximately only 3% of patients requiring operation, alternative reconstructive techniques, such as "non-vein" bypass grafts and thrombendarterectomy are needed.

Adult↗
PubMed1980

Intra-operative graft blood flow related to failure of femoro-popliteal bypass grafts.

The prognostic significance of intra-operative blood flow, as measured by electromagnetic flowmetry, was investigated in 127 limbs, which were operated on with a reversed femoropopliteal saphenous vein bypass graft because of symptomatic atherosclerotic occlusion of the superficial femoral artery. Thromboses occurring in the first postoperative month are defined as early failures and thereafter as late failures. There were three early graft failures. The basal and augmented flow rates during pharmacological vasodilation of these grafts were less than half those of the grafts remaining patent. Eight additional late graft occlusions occurred. Whereas the basal blood flow of these grafts did not differ significantly from that of the grafts which remained patent, the maximal flow rate was significantly lower (p less than 0.05). The overall incidence of graft failure at basal and maximal flow rates of 100 ml/min or less and 150 ml/min or less, respectively, was 35%, while, at higher flow rates, this incidence was reduced to 5% (p less than 0.001). This study emphasizes that intra-operative femoropopliteal vein graft flow provides prognostic indications of graft failure.

Adult↗
PubMed1980

Pharmacological vasodilation during reconstructive vascular surgery.

The effect on graft blood flow of two vasodilatory drugs, papaverine and bamethane (Vasculat), was infestigated by electromagnetic flowmetry intra-operatively in 31 patients following vascular reconstruction with a femoro-popliteal reversed saphenous vein bypass graft. With both drugs, graft flow augmentation was dose dependent (p less than 0.01) with increasing flow rates up to the injection into the popliteal artery of 40 mg of papaverine and 100 mg of bamethane respectively. The increase in graft flow rate was significantly more pronounced during vasodilation with 40 mg of papaverine than when 100 mg of bamethane was injected (p less than 0.001). Furthermore, 40 mg of papaverine and 100 mg of bamethane respectively induced a significantly larger increase in graft blood flow when injected into the popliteal artery than into the common femoral artery (p less than 0.01). The interpretation of these findings is discussed, and the augmented graft flow values presented are compared to those previously reported. From the present results, it is recommended that, for 'maximal' intra-operative flow augmentation, papaverine should be used, the dose being 40 mg injected into the popliteal artery or into the graft, but not into the common femoral artery or elsewhere intra-arterially.

Aged↗
PubMed1979

Conversion of arachidonic acid to prostaglandins in homogenates of human skeletal muscle and kidney.

The capacity of human skeletal muscle and kidney homogenates to synthetize prostaglandins (PGs) from exogenous precursor was investigated. Low-speed supernatants of muscle as well as renal medullary and cortical homogenates were incubated with 14C-labelled arachidonic acid (14C-AA) prepared as a sodium salt. 14C-PGs in the incubates were extracted, separated with thin-layer chromatography (TLC) and quantified by radioscanning. In the skeletal muscle incubates 14C-AA was converted into 14C-PGs with a time-dependent yield, most effectively after 10--15 min incubation. Well-defined radiopeaks parallel to unlabelled standards of PGD2, PGE2, PGF2 alpha and 6-keto-PGF1 alpha were obtained in the chromatograms. PGE2 was the main PG formed, constituting over 50% of 14C-activity, whereas 6-keto-PGF1 alpha, PGD2 and PGF2 alpha were found in considerably lower proportions. In the renal medullary incubates, PGE2 likewise accounted for the largest part of 14C-PGs formed, but significant relative amounts of PGF2 alpha and PGD2 were also found. A minor peak, corresponding to 6-keto-PGF1 alpha and thus indicating formation of PGI2, was also obtained. In contrast to the medulla, no 14C-PGs could be found in the renal cortical incubates. The results demonstrate the existence of a considerable tissue specificity in the quantitative and qualitative expression of PG biosynthesis in man.

Adult↗