Werner Irnich

Threshold measurements: ten rules for good measuring practice.

The following rules for professionally measuring thresholds are derived and discussed:

Compendium of Pacemaker Technology. II

The simplest pacemaker is one that emits pulses at a fixed interval without being influenced by the hearts activity. A pacemaker with no sensing function is called a fixed rate or asynchronous pacemaker; when spontaneous heart actions occur, competition will be produced between the electrically generated impulse and the spontaneous beat. A fixed-rate pacer may fire arbitrarily in any and every phase of the hearts cycle, occasionally producing uncomfortable irregularity of the heart beat and rarely ventricular fibrillation.* To avoid this, non-competitive pacemakers were designed which coordinate their function with that of the heart by sensing, via an electrode, the electrical activity of the heart. This ability to detect the cardiac activity is called the sensing function of a pacemaker. In order to prevent recycling of the generator by its own output or by the hearts response, the pulse generator is designed to be non-sensing [refractory period] for a short

Compendium of Pacemaker Technology II. DEFINITIONS AND GLOSSARY (PART III)

In its simplest form a pacemaker has the task of converting the energy of its power supply into electrical impulses. The longevity of a pacemaker is, therefore, directly dependent on the storage capability of its batteries. (A battery is a unit, often comprised of several celJs.) Primary ceJJs possess two different chemical substances that produce electrons by their chemical reactions. When two different metal electrodes are immerged into an electrolyte, ions are dissolved that, if negatively charged, wander to the anode (electrode collecting the negative charge) or, if positively charged, to the cathode (electrode collecting the positive charge). The primary cell as a voltage source has the negative charge collecting anode as its negative pole and the cathode as its positive pole. Almost all primary cells used within the past 18 years were composed of zinc (Zn) as the anode and mercuric oxide (HgO) as the cathode. In modern batteries, lithium (Li) is used as the anode, but the cathode material may be a variety of different substances.

Gender differences in pacemaker therapy

Nowak and Misselwitz1 state in their paper on Gender difference: ‘Unfortunately, our data does not allow us to provide a reliable explanation for these gender differences’. Nielsen2 utters in his Editorial that ‘the difference observed between men and women regarding the pacing mode selection has not been found in previous large cohort studies’ and he adds that ‘the reason for this difference among genders is largely unknown’. We have investigated the problem of ‘gender bias’ in several papers3–6 in which we described gender differences and tried to find an explanation for the female ‘discrimination’. We found in a study that pacemaker-dependent women with AV block had 1.17 times more VVI pulse generators when compared with the corresponding male group, whereas this ratio was 1.22 for non-dependent patients. With the indication SSS, the ratio was 1.08.4 Investigating different age groups on the basis of 21 968 new …

IN MEMORIAM.: Seymour Furman

At the 8th International Conference on Medical and Biological Engineering in Chicago, Palmer House, in 1968 I first met Dr. Seymour Furman. He was chairing the session on “Cardiac Pacing” and I had a presentation during that session on “Possibilities to control implanted pacemakers.” It was my very first presentation in English. Realizing my very limited knowledge of English, Dr. Furman bent down to me and offered to assist me during the discussion, if necessary. This incident hints at a very fine character trait of Dr. Furman. He was always willing and prepared to help younger and inexperienced colleagues, especially if they were non-English speakers. Since that experience in 1968 our mutual relationship steadily grew so that by the middle of the 1970s we were good friends. I admired “Sy” for his pioneer work in cardiac pacing. His merits in this field are indisputable. Together with G. Robinson in 1958, it was he who introduced transvenous access to the right ventricle, a method that made implantation of a lead by thoracotomy dispensable. This was the prerequisite for establishing cardiac pacing as a routine therapy. He organized the first international conference in this field entitled “Advances in Cardiac Pacemakers” held by The New York Academy of Sciences in 1968, and published in the Annals of the New York Academy of Sciences in 1969. This was the origin of what was later called the “World Symposium on Cardiac Pacing.” As far as I can judge as an engineer, Sy was one of the first to treat topics such as:

Report of the policy conference on computer communications in pacing sponsored by the North American Society of Pacing and Electrophysiology. October 13, 1987.

The proliferation of computer applications in clinical pacing and electrophysiology, together with the growing use of computers for the management of clinical, scientific, and administrative data, has created a manifest need for widely accepted standards for communication between a host computer used in a pacemaker cHnic or implantation facility, and a variety of peripheral instruments. Such instruments include pacemaker systems analyzers pacemaker programming devices, clinic follow-up measurement devices, transtelephonic-monitoring receivers, and electrophysiology-laboratory stimulators.

Seven Years of PACE Data Cards

More tban 300 pacemaker models bave been described and published as PACE Data Cards since January 1978. Nevertheless, the goal of making data available for all existing pacemakers has not been achieved. A few manufacturers, newcomers to the market, have not provided data and others have had difficulties in supplying data concerning the most recent generation of devices. It sometimes seems that production of a new model is easier than development of data concerning its functional characteristics and that some marketing departments are oblivious to the opportunity to use PACE Data Cards as free advertising! The reason may be that more detail is required by the PACE Data Cards than is usually printed in a manufacturers brochure. Provision of this information requires additional work and this requirement alone may jeopardize cooperation. Not every manufacturer wants data published simultaneously with market release. If data is not published, parameters can be changed if early implantation reveals design inadequacies; but, seemingly, the major reason is the high turnover rate of persons responsible for delivering data. This author finds that he often deals with different people in industry. This lack of continuity is probably the greatest barrier to achievement of the goal of early and complete publication of data.