Nuclear batteries....

[Nowhere]

Although it is clear form my previous responses that I have nothing against "nucular", I think this is much better suited for pacemakers and the like.

[Brian Ellis]

Does the pacemaker send the electronic impulse from the chest or are there actually wires attached to the heart?

Basically, it is as Doc says, but there are two kinds of wire used. Bipolar electrodes are used where there is hope of obtaining natural pacing, one pole to receive the natural signal and the other to send the artificial one. The cable itself is coaxial and the sensor electrode is in the heart chamber, whereas the other one is in contact with the muscle. The unipolar cable is just to send an impulse.

In my case I had a partial A/V block (typically the ventricle would work 1/3 of the time) and they put in bipolar cables to both the auricular and ventricular chambers. Diagnosis showed that the ventricle was hardly ever receiving a natural signal (the bundle of Hess was faulty) and the cable itself was showing signs of problems so, when they replaced the pacemaker in 1998, they replaced also the V cable with a unipolar one, meaning that the pulses to the ventricle are derived 100% synthetically from the auricular signal.

During the annual control, they stop the pacemaker for a few tens of seconds to determine the natural functions, by placing a magnet over it. My ventricles hardly even flutter now, although the auricles are in reasonably good shape on the natural beat. I suppose I theoretically die during those controls if you count arrested blood flow to the brain as the cause of death! I guess I've died about 20 times, so far Actually, it's not as bad as it sounds; a slight wooziness is all you feel. The interactive programming is done via a magnetic induction link (like a transformer with one coil in the device and the other outside the body). There are about 50 programmable parameters in modern pacemakers. Fortunately the OS is not Windows, otherwise it would be renamed Curtains!!! The downside is that my body is sensitive to external magnetic fields, which is why I can't go through metal detectors at airports or elsewhere.

My next pacemaker control is on Tuesday, which is why I'm typing this from Switzerland.