PubMed Health⌕ Search

Biomedical subjects

H Lagergren

Publications and source records attributed to H Lagergren.

15 recordsLinked to original sources
PubMed1979

Long-term observation of pacemaker electrodes. A follow-up study of 328 consecutive patients treated between 1959 and 1967.

Epicardial electrodes implanted in 20 patients between 1959 and 1962 had a short-term effectiveness. A change to endocardial stimulation was later necessary in 15 of these patients. Endocardial electrodes inserted between 1962 and 1967 in 306 patients were included in this study; 121 (40%) of these patients survived for 10 years or more. Seventy-five (62%) of the long-term survivors had no problems with their electrodes. In 39 of these patients the stimulation thresholds were measured after both 5 and 10 years and found to be 2.3 +/- 0.6 volts and 2.2 +/- 0.8 volts, respectively. Hence, long-term complication-free endocardial pacing can be accomplished.

Adult↗
PubMed1978

Influence of output capacitor, electrode and pulse width on power consumption in cardiac pacing.

Three different types of unipolar endocardial electrodes--47 in all--were compared in regard to power consumption at stimulation threshold with six different output capacitors and seven pulse widths. Fifteen were conventional large surface electrodes (area 47 mm2); 18 were conventional small surface electrodes (area 6 mm2), and 14 had a specially designed tip with a large area but small active surface of 8 mm2. Pulse widths ranged from 0.15 to 2.0 msec and output capacitors from 1.0 to 22.0 microFarads. All in all about 2,000 measurements were performed. The average current drain to the pacemaker output stage was measured and power consumption was calculated for each electrode--pulse width--output capacitor combination. In all combinations, the two small surface electrodes consumed approximately the same amount of power and, in both cases, significantly less than the larger one. With regard to power economy at stimulation threshold, the pulse width of choice was about 0.5 msec and, furthermore, power consumption decreased with increasing capacitor size. The optimal combination was a small surface electrode, an output capacitor of 22 microF and a pulse width of 0.5 msec.

Adult↗
PubMed1977

Prevention of platelet adhesion and aggregation by a glutardialdehyde-stabilized heparin surface.

A stable heparinized surface was prepared by sequential treatment of polyethylene with water solutions of hexadecylamine hydrochloride, heparin and glutardialdehyde. In order to explain the "non-thrombogenic" properties of this surface, it was evaluated with regard to prevention of platelet adhesion and aggregation. Human heparinized blood (2 and 10 IU/ml) with 51Cr-labelled autologous platelets was rotated for 60 minutes in untreated and heparin-treated circular tubings. The surface area/blood volume ratio was varied and an air-blood interface was present. In untreated tubings, platelet adhesion and aggregation increased in proportion to the size of the surface area/blood volume ratio, irrespective of the heparin concentrations of the blood. In the heparin-treated tubings, there was no measurable platelet adhesion to the surface and no platelet aggregation in the blood. The difference between the heparinized and the untreated surfaces with regard to platelet adhesion was discernible even after 10 minutes storage of stagnant blood. It is concluded that platelet adhesion and aggregation induced by exposure of blood to a foreign surface in an in vitro experimental model can be prevented by a stable heparin coating of the surface.

Aldehydes↗
PubMed1977

Deleterious effects of cardiac pacing in a patient with mitral insufficiency.

A 70-year-old, artificially paced women with dizziness and extremely low physical capacity exhibited a systolic BP varying from one moment to another; in standing position it was not measurable. With the aid of a strain gauge technique, the amplitude of the pulse wave of her left thumb was recorded and shown to vary widely. The variations were correlated to synchrony or asynchrony between atrial and ventricular activity. Pronounced decreases in stroke volume and peripheral pulse volume were recorded with pacemaker-induced beats compared with idioventricular beats. With artifical stimulation at a rate of 45/min, thus avoiding competition but still protecting her from syncopes, she was free from symptoms.

Aged↗
PubMed1976

Effect of low-dose heparin prophylaxis on arterial oxygen tension after high laparotomy.

The effect of low doses of heparin (5000 units of sodium heparin every 12 hours for 5 days) on arterial oxygenation was studied in 24 patients in the postoperative period after upper abdominal surgery. Another 24 patients served as a control group. The arterial oxygen tension was the same in both groups preoperatively and was equally significantly reduced during the 1st postoperative day. During the 2nd day, oxygen tension rose in the heparin-treated group to values which no longer differed significantly from the peroperative level. In the control group the significant reduction persisted until the 4th postoperative day. The arterial carbon-dioxide tension did not differ between the groups, neither did it vary significantly between days. There were no clinical signs of large pulmonary embolism during the postoperative period, chest X-ray was normal in all patients examined and a photoscan was normal in 23 of 24 subjects studied. Low-dose heparin treatment may apparently shorten the period of postoperative hypoxaemia, probably by counteracting both large pulmonary emboli and microthromboembolism.

Adult↗
PubMed1976

Effect of low-dose heparin on the phagocytic and catabolic function in the reticulo-endothelial system in man during surgery.

The effect of subcutaneous low-dose heparin prophylaxis on the phagocytic and catabolic functions of the reticuloendothelial system (RES) was studied in 10 patients undergoing elective cholecystectomy. The patients were divided into two groups; 5 patients receiving 5 000 units of heparin preoperatively and every 12 hours following the operation and 5 patients given saline at the corresponding time. Each patient served as his own control, when the RES function was tested twice with microaggregated human serum albumin labelled with 125I as a test substance. There was an enhanced phagocytic activity and a correspondingly raised catabolic activity of the RES in patients treated with heparin. The reasons for this are discussed. The results indicate that heparin in low doses has a favourable effect on the RES.

Heparin↗
PubMed1976

A low-threshold, non-dislocating endocardial electrode.

Threshold curves with large and small surface intracardiac pacemaker electrodes are compared. The 2 msec. impulse threshold with a 47 sq. mm. electrode was 3.6 v. (4.3 mA.) on the fourteenth postoperative day, when it reached its maximum, and 2.8 v. (3.1 mA.) one month after the operation. These values were 45 and 30 per cent lower with a 6 sq. mm. electrode. Thresholds increased by about 20 per cent when the impulse duration was shortened from 2 to 0.5 msec. The small surface electrode consumed about 35 per cent less current than the 47 sq. mm. one. A newly designed large area-small surface electrode with the shape of an open cage, seems to have the advantages of less increase in postoperative thresholds and good attachment to the endocardial wall.

Arrhythmias, Cardiac↗