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Biomedical subjects

H Strandberg

Publications and source records attributed to H Strandberg.

15 recordsLinked to original sources
PubMed2001

Combipolar sensing in dual chamber pacing: is there still a need for bipolar leads in the atrium?

Bipolar leads have been shown to provide superior sensing conditions compared to unipolar leads as bipolar sensing is less susceptible to interference. However, the mechanical long-term integrity and longevity of bipolar leads is inferior to that of unipolar leads. A prospective randomized, multicenter study was performed to investigate a new atrial detection configuration called combipolar sensing. This new sensing concept is designed for the use of conventional unipolar leads in the atrium and the ventricle. While the atrial stimulation is unipolar, atrial sensing is accomplished in a bipolar way using the ventricular lead tip as the indifferent electrode. A modified dual chamber pacemaker provided with this sensing concept was implanted in 26 patients. At predischarge and at the 1- and 3-month follow-ups no significant differences in atrial sensing thresholds and P wave amplitudes were found between the unipolar and the combipolar sensing configuration at rest or during provocation. Myopotential inhibition could be demonstrated in 22 patients during unipolar sensing at sensitivity settings as "low" as 2 mV. In contrast, during combipolar sensing it could only be demonstrated in one patient once and only at the highest atrial sensitivity of 0.5 mV. Combipolar atrial sensing is feasible under normal conditions and during provocation. Myopotential interference is negligible. Thus, combipolar sensing offers comparable atrial sensing to bipolar without the disadvantages of a bipolar lead.

Adolescent↗
PubMed2001

[Frans Johan Rabbe: the father of the history of medicine in Finland].

F. J. Rabbe is the one who can be regarded as the real father of the history of medicine in Finland and who also was a member of the Medical Board. It was Rabbe who already in 1843 wrote the first paper on the history of different types of hospitals such as the leper hospitals, the county hospitals, the hospitals for veneral diseases as well as the military and psychiatric hospitals which gradually had been established in Finland since the middle of the 14th century. Rabbe also collected and published all the medical laws and decrees issued in Finland between 1683 and 1845. Later Rabbe published a lot of different statistical material on medical conditions in Finland as well as biographies of medical doctors. He also made a comprehensive work on the history of medicine in Finland, about 3000 handwritten pages, which unfortunately only has been saved as a manuscript and has not been published(5).

Finland↗
PubMed1997

[Not Available].

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Finland↗
PubMed1994

A new dual chamber single lead system.

A DDD pacing system normally requires the introduction and positioning of two separate electrode leads. A VDD system may use a single lead with a ventricular electrode at the tip and at least one atrial ring electrode. The disadvantage of VDD systems is that the full range of DDD stimulation and detection alternatives is not available. The present animal study was made to evaluate a new single lead design with the distal electrode placed in the atrium and the proximal ring electrode in the right ventricle. This design permits the full range of DDD options including atrial stimulation. Acute stimulation thresholds and sensing amplitudes were stable and comparable to conventional DDD systems. Long-term studies are on-going.

Animals↗
PubMed1994

[Medical history education in Finland - some reflections].

Since the nineteen twenties in Finland there has to a varied extent been lectured in "Medical History". It was not a compulsory subject but from the nineteen thirties and until the end of the nineteen fifties it was included in the programme for the University of Helsinki. After a pause of 15 years lecturing in Medical History began again in 1975, with an offer of a course of 20 hours. Two years later this course was extended to 36 hours and was now compulsory for everyone, but in 1980 the hours were reduced to 16. In 1985 the course was changed again, now it became a voluntary with 15 hours lecturing.

Education, Medical↗
PubMed1992

[Not Available].

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Finland↗
PubMed1989

[Not Available].

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Finland↗
PubMed1988

[Not Available].

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Finland↗
PubMed1986

[Not Available].

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Academies and Institutes↗
PubMed1985

Valsalva-induced variations in the intracardiac signal.

Variations in the intracardiac signal may substantially affect the sensing function of cardiac pacemakers. As the Valsalva maneuver causes a change in heart volume, its effect on the intracardiac signal was studied in seven patients with an adequate escape rhythm who had permanent ventricular pacemakers. During generator replacement, they were asked to perform a standardized Valsalva maneuver. An increase from the baseline amplitude ranging from 5% to 70% was noted during forced expiration against the closed glottis. There was a decrease from the baseline ranging from 15% to 50% after termination of this maneuver. Similar changes were noted for the rate of voltage change (slew rate). The magnitude of these alterations was most pronounced in patients with comparatively low intracardiac amplitudes. Because marked changes in the intracardiac signal can result from the Valsalva maneuver, it might be an important source of undersensing among patients with permanent pacemakers.

Aged↗
PubMed1979

Spectral properties of atrial and ventricular endocardial signals.

The spectral energy distributions of signals picked up by endocardial, atrial and ventricular electrodes have been investigated. The results show similar spectral distributions for P-waves and QRS-complexes with maximum spectral densities at frequencies between 10 and 30 Hz.

Adult↗