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Biomedical subjects

B Lemke

Publications and source records attributed to B Lemke.

45 records · Page 3Linked to original sources
PubMed1991

[Intolerance reactions to ionic and nonionic contrast media in cardiac diagnosis. A randomized double-blind study].

Reactions to an ionic and a nonionic contrast medium were compared in a randomized double-blind trial involving 1153 patients (897 men, 256 women; mean age 56 [18-84] years) who underwent left-heart catheterization with coronary angiography. 584 patients (group 1) received the ionic contrast medium meglumine diatrizoate (Urografin 76%), while 569 (group 2) received the nonionic iopromide (Ultravist -370). Reactions of skin and mucosae, heart and circulation, lungs and respiratory tract, as well as of the central nervous system were noted. There was no significant difference between the two groups with respect to age, weight, height, allergic predisposition, left-ventricular ejection fraction, or serum electrolyte concentrations. Mild reactions, not requiring any treatment, occurred in 108 of the 1153 patients (9.4%), 85 (14.6%) in group 1 and 23 (4%) in group 2 (P less than 0.001). Severe reaction requiring treatment occurred in eight patients of group 1 (1.4%) and 14 of group 2 (2.5%)--difference not significant. Ventricular fibrillation was more frequent among group 2 patients (four compared with one in group 1), while two of three asystoles requiring treatment occurred in group 1 patients. The results show that, while mild reactions not requiring treatment were clearly less frequent after nonionic contrast medium injection, the risk of severe reactions was not reduced by their use.

Adolescent↗
PubMed1991

[Strut fracture of a convex-concave 60 degree Björk-Shiley mitral valve prosthesis 5 years after implantation--metallurgic analysis of the prosthesis strut].

Acute mechanical failure of prosthetic heart valves is rare, but associated with high mortality when occurring. For convexo-concave Björk-Shiley prostheses only fractures of the outlet strut are reported. We present a case of lethal mechanical complication 5 years after implantation. By additional metallurgic analysis we were able to identify a sequential course of the outlet strut fracture. This could lead to new approaches for early detection of this complication.

Adult↗
PubMed1990

[Effect of AV synchronization and rate increase on hemodynamics and on atrial natriuretic peptide in patients with total AV block].

We studied nine patients (56 +/- 7 years) with complete AV-block and permanent dual-chamber pacemaker (DDD) under different pacing modes: ventricle pacing (VVI) 70 bpm, DDD 106 +/- 4 bpm, rate adaptive pacing (VVI-FA) 108 +/- 3 bpm. Exercise was performed supine on the bicycle ergometer at 50 watts for 5 min at each setting. DDD-paced patients showed significantly higher mixed venous oxygen saturation, being 45 +/- 2% after the fourth minute, (VVI 38 +/- 2%, p less than 0.01 and VVI-FA paced patients 40 +/- 1%, p less than 0.01). Pressures were normal under DDD pacing during exercise (RAP 7 +/- 2 mm Hg; PCP 14 +/- 3 mm Hg) and showed further increase to abnormal levels during VVI (RAP 13 +/- 2 mm Hg, p less than 0.01; PCP 21 +/- 3 mm Hg, p less than 0.02) and VVI-FA pacing (RAP 10 +/- 2 mm Hg, p less than 0.05; PCP 20 +/- 3 mm Hg, p less than 0.01). Stroke volume increased from 71 +/- 5 ml to 105 +/- 7 ml during VVI and from 64 +/- 7 ml to 81 +/- 7 ml during DDD pacing. Stroke volume remained unchanged (69 +/- 5 ml) during VVI-FA pacing. The peak levels of ANP during and after exercise were significantly higher under VVI (951 +/- 248 pg/ml) than under DDD pacing (650 +/- 140 pg/ml, p less than 0.01) and were not different between DDD and VVI-FA pacing (677 +/- 97 pg/ml). These results show that VVI pacing effects a more pronounced increase of ANP level than other pacing modes. Under moderate exercise, rate-responsive pacing compared to VVI pacing showed no differences in mixed venous oxygen saturation and in atrial pressures. Only DDD pacing showed higher oxygen saturation and a normalization of atrial pressures when compared to other types of single chamber pacing.

Atrial Natriuretic Factor↗
PubMed1989

The atrial pacemaker: retrospective analysis of complications and life expectancy in patients with sinus node dysfunction.

The safety of atrial pacemakers is still a remaining cause of controversy. Since 1972, we have implanted 111 atrial pacemakers and we were able to follow-up 100 patients continuously. Mean follow-up time was 47 +/- 36 months (maximum 154 months) with a total population time of 391 patient years. Over a period of 10 years, the cumulative incidence of complete atrioventricular block was 4% (2 patients). The cumulative incidence of atrial fibrillation was 11% (5 patients). Lead-related complications were strongly dependent on the type of the lead and the mode of fixation. The cumulative incidence of all lead-related problems was 19% over a period of 5 years and 33% over a period of 10 years. The cumulative survival rate was 85% for 5 years and 61% for 10 years. These survival rates were not different from the survival rate of a matched cohort of the normal population. We conclude that atrial pacing could be done in patients with sick sinus syndrome. The risk of developing a complete atrioventricular block seems to be rather low. The main problem of the atrial pacemaker is the fixation of the lead which could be reduced by using screw-in-type leads.

Adult↗
PubMed1987

[The atrial pacemaker as therapy in sinus node disease: retrospective analysis of complications and rate of survival].

The implantation of an atrial pacing device represents an established mode of therapy for bradycardia in sinus node dysfunction. However, controversial views remain concerning the safety of this type of pacing. To investigate this, we retrospectively analysed data from 81 patients, all of whom received an AAI pacing device between 1972 and 1984. Complete AV-block developed in two out of 81 patients (cumulative incidence after 10 years was 5 +/- 3%). Atrial fibrillation developed in three out of 81 patients (cumulative incidence after 10 years was 10 +/- 5%). Lead-related complications were strongly related to the type of lead tip and the mode of fixation. The overall incidence of lead-related problems was 20 +/- 5% after 5 years and 38 +/- 12% after 10 years. 82 +/- 6% of patients survived the first 5 years, 52 +/- 14% survived for 10 years. The 5 years' survival rate was not different from that of the normal population. From this we conclude that atrial pacing can be safely done with an AAI system as long as there are no signs of an AV-block. Atrial fibrillation develops less often on AAI pacing than on VVI pacing. The risk of developing an AV-block seems rather low.

Aged↗
PubMed1982

Characterization of the fast sodium current in isolated rat myocardial cells: simulation of the clamped membrane potential.

1. The fast sodium inward current of freshly isolated single rat myocardial cells was studied by means of the internal perfusion-voltage clamp method. 2. The voltage dependence of this current did not differ from the current-voltage characteristics of the fast sodium inward current described for other excitable cells and tissues. 3. The time constant of inactivation of the Na+ current of the isolated myocardial cells ranged between 5.2 msec at -58 mV and 0.5 msec at +18 mV. The activation time constant ranged from 0.3 msec at -55 mV to 70 microseconds at +10 mV. 4. The reactivation time constant of the maximum sodium current at a holding potential of -100 mV was found to be 21 +/- 5 msec. 5. A mathematical model was developed for the simulation and analysis of the influence of the series and shunt resistances on the time response of the membrane potential. The results of the modelling make it clear that control of the series and shunt resistances in any given experiment is a conditio sine qua non for a valid analysis of the kinetic parameters of the sodium inward current. 6. Sodium currents with delayed activation kinetics must be regarded as an indication of insufficient control of the membrane potential.

Animals↗