[Acute aortic dissection].
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Acute Disease↗
Biomedical subjects
E Hjelms
Publications and source records attributed to E Hjelms.
[Diaphragm pacing by electric stimulation of the phrenic nerves].
Artificial ventilation by electric stimulation of the phrenic nerves has become clinically significant within the past 20 years and, in the world as a whole, approximately 700 patients have been treated with implanted diaphragmatic pacemakers. The two first patients in whom diaphragmatic pacemakers were implanted in Denmark, had sustained accidental fractures of the second cervical vertebra with subsequent high cervical spinal cord lesions with not only tetraplegia but also respiratory arrest. In both patients, diaphragmatic pacemakers were implanted bilaterally and these were employed for 12-14 hours daily while ventilation with a respirator was employed at night. The main indications for diaphragmatic pacing are paralysis of respiration following high cervical spinal traumata and the chronic central hypoventilation syndrome (sleep apnoea of Undine's curse). Diaphragmatic pacing may improve the mode of ventilation and the quality of life for patients with tetraplegia and respiratory insufficiency. On account of the potential technical problems, the risk of complications and the limited number of patients in whom this operation is suitable, implantation of diaphragmatic pacemakers should be concentrated in a few centres and probably only one in Denmark.
Adolescent↗
Inferior infarction with large nonapical mobile thrombus mimicking myxoma.
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Adult↗
[Results with the Ionescu-Shiley bioprosthesis].
During the period 1.1.1982-31.12.1987, 61 patients were submitted to operative introduction of the Ionescu-Shiley pericardial xenograft. The indications were anticipated brief survival or conditions which rendered anticoagulation therapy undesirable. Because of this, the operative lethality was high (12/61). No thromboembolic complications were observed during a period of observation of up to five years and no cases of primary destruction of valvular tissue.
Adult↗
A surgical model to study in vivo efflux of cholesterol from porcine aorta. Evidence for cholesteryl ester transfer through the aortic wall.
We describe a surgical procedure in pigs which makes it possible to follow the influx into, the penetration through and the efflux from the arterial wall of labeled lipoproteins. After 4 h exposure of the luminal side of the arterial wall to labeled lipoproteins, labeled esterified cholesterol was found in all layers of the aortic wall, whereas labeled free cholesterol gained access only to the most luminal layer. The data suggest that at least 40%, if not 80-90%, of the cholesteryl ester that enters the aortic wall from the luminal side, passes through the entire wall and leaves the aortic wall through vasa vasorum and lymphatics. They also suggest that free cholesterol in the lipoproteins exchanges extensively with cellular free cholesterol while the lipoproteins penetrate through the most luminal layer. More than 90% of the labeled cholesteryl ester disappeared from the arterial wall during a cold chase period of 4 days. By the simultaneous use of [3H]cholesterol and [14C]cholesterol it was shown that only 10-20% of this disappearance can be explained by cholesteryl ester hydrolysis in the arterial wall.
Animals↗
Intravascular air after fibrin sealing by spray gun in cardiovascular surgery.
During an operation for an ascending aortic aneurysm with implantation of a saphenous vein graft to the left coronary artery into a prosthesis, we occasionally observed air bubbles in the graft after application of fibrin glue to the anastomosis to control bleeding. In an experimental study in a pig, a vascular prosthesis was anastomosed to the descending aorta. The aorta and the prosthesis were transected and reanastomosed. Air bubbles were collected in a glass flask placed at the end of the prosthesis. Fibrin glue was applied with a spray catheter on all anastomoses at varying distances and with different air pressures. Small amounts of air were collected in the glass flask when an air pressure of 3 or 4 bar was used. This study demonstrates that the use of fibrin glue in cardiovascular surgery can introduce air into the vascular system with subsequent air emboli as a possible side-effect.
Aged↗
Beta 2-mediated changes in central haemodynamics, coronary circulation and myocardial metabolism in canine.
The combined effect of terbutaline on systemic and coronary circulation was investigated in dogs to clarify its influence on myocardial oxygen supply and lactate balance. The dogs were anaesthetized and the chest opened. Coronary sinus blood flow and cardiac output were monitored by thermodilution, aortic pressure was measured by tip-transducer and heart rate by RR-interval on ECG, coronary sinus blood were analyzed for lactate, oxygen and carbon dioxide. Terbutaline caused a substantial systemic vasodilation and an increased heart rate, the total external cardiac work increased to a minor degree. Terbutaline increased arterial lactate concentration. Coronary vascular resistance was reduced after terbutaline. Even if myocardial perfusion pressure was reduced and an increased external cardiac work was present, no signs of myocardial distress was observed in lactate metabolism or coronary sinus oxygen content. In fact a tendency to increased myocardial aerobic metabolism was observed, as myocardial lactate consumption increased after terbutaline. Terbutaline seems to be a coronary vasodilator in dogs. However, the demand for oxygen secondary to both an increase in cardiac work and aerobic metabolism can be hazardous to the potentially ischaemic myocardium.
Animals↗
[Bronchoplasty--an important alternative for lung resection].
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Adolescent↗
Evaluation of increased serum creatine kinase as an indicator of irreversible myocardial damage in dogs.
To evaluate the relationship between creatine kinase (CK) elevation and irreversible myocardial damage, a coronary artery branch was occluded for periods of 5 to 40 min in ten dogs. In five other dogs the coronary vessel was occluded for 480 min, and five dogs underwent the same operative procedure but without occlusion of the artery. The serum CK was monitored for 8 hours postoperatively in all dogs. Elevation of the CK levels occurred in all groups, but the area under the time-enzyme activity curve showed no statistically significant difference between the group with 480-min occlusion, in which transmural myocardial infarction occurred in all dogs, and the group with temporary occlusion, in which no infarction could be histologically or histochemically demonstrated. Contrastingly, a statistically significant difference was found between the group with temporary occlusion and the control group with no occlusion. The results suggest that CK elevation is of no value as an indicator of irreversible myocardial damage during heart surgery that involves temporary myocardial ischaemia.
Animals↗
Intracellular metabolism in biopsies from the aorta in patients undergoing coronary bypass surgery.
Abnormal glucose and lipid metabolism in striated muscles and arterial wall has been demonstrated in 3 species: the pig, the dog, and human Type 2 diabetic patients, sharing the common feature of peripheral hyperinsulinaemia. In this study eighteen consecutive patients undergoing coronary bypass surgery and eight control patients were examined. Prior to surgery an oral glucose tolerance test showed that eleven out of eighteen patients had impaired glucose tolerance and significantly elevated fasting immune reactive insulin (IRI) and C-peptide concentrations. There was a statistically significant correlation between the 2 hour blood glucose value and the fasting plasma insulin level (R = 0.55, p less than 0.05). During the operation, aortic and muscle biopsies were taken. The eighteen patients undergoing coronary bypass surgery showed disturbances in glucose metabolism, i.e. decreased activity of glycolytic enzymes (hexokinase 0.30 +/- 0.06 versus 0.40 +/- 0.06 U/g, p less than 0.001, and phosphofructokinase 0.48 +/- 0.09 versus 0.61 +/- 0.07 U/g, p less than 0.01). Malic enzyme activity was increased in all patients (0.17 +/- 0.03 versus 0.06 +/- 0.02 U/g, p less than 0.001). Glucose-6-phosphate dehydrogenase was increased in the eleven patients with impaired glucose tolerance (0.55 +/- 0.10 versus 0.30 +/- 0.07, p less than 0.01) parallel to a significant increase in triglyceride content in the aortic wall (16.1 +/- 4.8 versus 3.7 +/- 3.2 mumol/g, p less than 0.01) as well as in the striated muscles (374 +/- 44 versus 48 +/- 6 mumol/g, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
Aorta↗
In vivo transfer of cholesterol from plasma into human aortic tissue.
It has recently become possible to measure the in vivo flux of cholesteryl ester from plasma into human aortic tissue by use of labeled cholesterol in patients undergoing reconstructive aortic surgery. For the ascending thoracic aorta without visible atherosclerotic lesions the influx was 4.5 +/- 1.4 nmol X cm-2 X day-1 (means +/- SEM, n = 9). For the abdominal aorta with severe atherosclerosis the influx of cholesteryl ester was 45 +/- 5 nmol X cm-2 X day-1 (n = 12). In both types of tissues the influx of cholesteryl ester from HDL was 2-3 times higher than the influx of cholesteryl ester from LDL and VLDL compared with the concentration of these fractions in plasma. This is in accordance with an aortic influx-mechanism which depends on the sizes and the concentration of the lipoproteins in plasma. The transfer of plasma lipoproteins into human aortic tissue shows a number of similarities with the transfer of plasma lipoproteins into the aortic wall of cholesterol-fed rabbits and also with the transfer of other plasma macromolecules across various capillaries. The cholesterol content in intima-media tissue without lesions corresponded in some of the patients to less than one year of continuous influx of cholesteryl ester from plasma. This time is short compared with the age of the patients. It suggests that removal of cholesterol from the aortic wall represents a major importance in prevention of cholesterol accumulation in that tissue.
Aorta↗
[Unstable angina pectoris. Indications for coronary arteriography and surgical treatment].
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Adult↗
Cerebral blood flow during cardiopulmonary bypass in man: effect of arterial filtration.
Cerebral blood flow was recorded in 39 patients undergoing cardiac surgery by intraarterial injection of xenon 133. There were three subgroups of patients: 10 patients had a 20 micron arterial filter (Johnson) and 11 a 40 micron filter (Pall), and 18 had no arterial filtration. All patients had a 40 micron (Pall) filter in the coronary suction line. Significant changes in cerebral blood flow occurred during extracorporeal circulation (p less than 0.0001). For all patients cerebral blood flow increased from a resting prebypass level of 30 to 46 and 57 ml/100 g a minute during initial and stable hypothermic extracorporeal circulation respectively. Both measurements were obtained at 26 degrees C and the recordings were made on average 12 and 55 minutes after the extracorporeal circulation was started. During rewarming cerebral blood flow increased to 64, 53, 41, and 36 ml/g a minute at 31 degrees, 33 degrees, 35 degrees, and 37 degrees C respectively, and when measured four and 16 minutes on average after bypass it was 44 and 41 ml/100 g a minute. This general brain hyperperfusion was noticed in all patients with a high enough mean blood pressure to produce hyperaemia. Interposing 20 and 40 micron arterial filters reduced cerebral blood flow but did not prevent this hyperaemia. The cerebral autoregulation, which maintains a constant cerebral blood flow within wide limits of perfusion pressures, was not affected by arterial filtration. The lower limit of blood pressure at which a further reduction in blood pressure was followed by a reduction in cerebral blood flow was around 60 mm Hg in all three groups.
Adult↗
Aprotinin does not add protective effect to cold cardioplegia during coronary artery bypass surgery.
The effect of aprotinin on intraoperative and postoperative CK-MB and left ventricular contractility in terms of dp/dt response to atrial pacing up to 150 beats/min was studied in 20 patients randomized before aortocoronary bypass surgery to either aprotinin or placebo administration. Cold cardioplegia and topical deep hypothermia were used in both groups. No difference could be demonstrated between the aprotinin and the placebo group, and the authors therefore concluded that aprotinin does not add substantially to the protective effect of cold cardioplegia and deep topical hypothermia during aortocoronary bypass surgery.
Aprotinin↗
Large granular-cell myoblastoma of the oesophagus.
A granular-cell tumour of the oesophagus, the largest hitherto described, was found in a 44-year-old woman. Histologic examination showed an infiltratively growing granular-cell myoblastoma without pleomorphism or mitotic activity. Local extirpation of the tumour was attempted in order to preserve oesophageal continuity. However, a tracheo-oesophageal fistula and stenosis of the previously tumour-bearing area developed and necessitated nasogastric tube feeding for 18 months. Two attempts to close the fistula, including resection of the fistula-bearing tracheal area, failed. Final cure was achieved by subtotal extirpation of the oesophagus and gastro-oesophageal anastomosis in the neck with the stomach placed retrosternally. Normal intake of food was restored after this operation and 30 months later the patient is doing well.
Adult↗
In vivo influx of free and esterified plasma cholesterol into human aortic tissue without atherosclerotic lesions.
In order to determine the in vivo influx of plasma cholesterol into human aortic intimamedia tissue, specimens of the ascending aortic wall without visible atherosclerosis were obtained from patients undergoing aortic valve replacement. Before the operation the patients were intravenously injected with autologous plasma in which the lipoproteins were labeled with radioactive cholesterol. The influence of the duration of the exposure time (0.3-114 h) and of the distribution of radioactivity between free and esterified cholesterol in plasma on the amount of radioactivity found in the arterial wall was studied by the simultaneous use of 3H- and 14C-cholesterol. It was shown that the influx of free and esterified cholesterol into the intima-media layer of the tissue could be calculated from a set of linear equations that relate the labeled sterols in the tissue to the average specific activities in plasma. In nine patients between 50 and 70 yr of age with 4.2-5.9 mM total cholesterol in plasma, the influx of free cholesterol and of esterified cholesterol was 1.2-8.8 and 1.0-12.5 nmol X cm-2 X d-1, respectively. Both hydrolysis and esterification of the sterol fractions in the aortic tissue and exchange of free cholesterol between the plasma lipoproteins and the tissue were demonstrated. The cholesterol content of the intima-media layer was 0.6-2.3 mumol X cm-2. This corresponds to the influx of esterified cholesterol during a period of only 0.1-3.5 yr, which is short compared with the lifespan of the patient. Our data thus suggest that removal of esterified cholesterol from aortic tissue without visible atherosclerosis represents a major importance for the cholesterol concentration in the tissue.
Adult↗
Escape of a leaflet from a St. Jude Medical prosthesis in the mitral position.
Twenty-three months after mitral valve replacement for mitral stenosis with a St. Jude Medical heart valve prosthesis size 31, a 29-year-old man suddenly went into a profound cardiogenic shock and pulmonary edema due to escape of one of the leaflets from the prosthesis. At emergency operation the valve was replaced with another type of prosthesis. The escaped leaflet was retrieved from the abdominal aorta and was found to be intact. The cause of the escape was found to be a fracture in the pivot area. Further examination with optic and scanning electron microscopy revealed an old fracture at the base of the pivot covered with organic material and another fracture at the top of the pivot area not covered with organic material and therefore probably very recent and responsible for the break-off of part of the area and subsequent escape of the leaflet. The cause of the primary fracture is unknown.
Adult↗
Brain hyperperfusion during cardiac operations. Cerebral blood flow measured in man by intra-arterial injection of xenon 133: evidence suggestive of intraoperative microembolism.
Cerebral blood flow (CBF) was measured by intra-arterial injection of xenon 133 in 29 patients during cardiac operations. Marked changes occurred in all patients. A normal and significant correlation with temperature and plasma PCO2 (p less than 0.01) support the reliability of the method. Mean CBF measured between sternotomy and the onset of extracorporeal circulation (ECC) was 38 ml/100 gm . min. The first minute of ECC was associated with a decrease in CBF in nine of 12 patients (p less than 0.02). During steady-state hypothermic ECC (temperature 29 degrees C), CBF increased unexpectedly to 64 ml/100 gm . min (p less than 0.01). Following rewarming steady-state normothermic ECC, mean CBF decreased to 42 ml/100 gm . min with signs of impairment of cerebral autoregulation. Ten and 20 minutes after termination of ECC, mean CBF was 40 and 41 ml/100 gm . min, respectively. Arterial PCO2 was found to be important in regulating CBF. The cerebral autoregulation maintained CBF down to arterial pressures of around 55 mm Hg. Below this level, CBF was significantly correlated with perfusion pressure (p less than 0.01). Multiple small emboli with a hyperemic border zone could cause a brain hyperperfusion, as seen in our patients during bypass. Measurements of CBF during ECC hold promise as a guide toward safer cardiac operations.
Adult↗