Monthly Archives: November 2012

Can heart beats really power cardiac pacemakers?

Baron von Munchausen

Today, I received a link (http://tweakers.net/nieuws/85353/hartslag-kan-pacemaker-van-stroom-voorzien.html) from Marijn, honorary member of the Biomedical Electronics Group, in which it is mentioned that researchers have found a way to harvest enough energy from a piezo-electric transducer so that a cardiac pacemaker can be powered from the heart itself. This would render the bulky batteries in the pacemakers unnecessary and the pacemaker thus does not have to be replaced after a couple of years because of a depleted battery.

I have two concerns about this. First, there is a kind of “Baron-von-Munchausen” effect. Baron von Munchausen was an 18th-century German nobleman, who, according to Rudolf Erich Raspe’s story The Surprising Adventures of Baron Munchausen, pulls himself out of a swamp by his hair (specifically, his pigtail). Now, let’s suppose that a pacemaker, equipped with a piezo-electric energy harvester to power the pacemaker, for no particular reason, fails to operate and the heart stops its precious beating, what will then power up the pacemaker again to make the beat again? Scary thought, isn’t it?

Second concern is of another nature. Pacemakers are usually replaced, not because the battery has depleted, but simply because a next generation pacemaker can provide a better therapy to the patient. As a side note, uncomfortable but true, current pacemakers (and thus also the batteries included therein) on average live longer than their owners. Hopefully this latter aspect will change for the better soon.

Wouter

Does enriched acoustic environment in humans abolish chronic tinnitus clinically and electrophysiologically?

Animal research has shown that loss of normal acoustic stimulation can increase spontaneous firing in the central auditory system and induce cortical map plasticity. Enriched acoustic environment after noise trauma prevents map plasticity and abolishes neural signs of tinnitus. In humans, the tinnitus spectrum overlaps with the area of hearing loss. Based on these findings it can be hypothesized that stimulating the auditory system by presenting music compensating specifically for the hearing loss might also suppress chronic tinnitus. To verify this hypothesis, a study was conducted in three groups of tinnitus patients. One group listened just to unmodified music (i.e. active control group), one group listened to music spectrally tailored to compensate for their hearing loss, and a third group received music tailored to overcompensate for their hearing loss, associated with one (in presbycusis) or two notches (in audiometric dip) at the edge of hearing loss. Our data indicate that applying overcompensation to the hearing loss worsens the patients’ tinnitus loudness, the tinnitus annoyance and their depressive feelings.
No significant effects were obtained for the control group or for the compensation group. These clinical findings were associated with an increase in current density within the left dorsal anterior cingulate cortex in the alpha2 frequency band and within the left pregenual anterior cingulate cortex in beta1 and beta2 frequency band. In addition, a region of interest analysis also demonstrated an associated increase in gamma band activity in the auditory cortex after overcompensation in comparison to baseline measurements. This was, however, not the case for the control or the compensation groups. In conclusion, music therapy compensating for hearing loss is not beneficial in suppressing tinnitus, and overcompensating hearing loss actually worsens tinnitus, both clinically and electrophysiologically.

2012 Published by Elsevier B.V, in Hearing Research, Hear Res. 2012 Oct 23. pii: S0378-5955(12)00244-4. doi: 10.1016/j.heares.2012.10.003. Authors: Vanneste Svan Dongen MDe Vree BHiseni Svan der Velden EStrydis CKathleen JNorena ASerdijn WDe Ridder D