Wang Zhonglin and Li Zhou explain the new cardiac pacemaker: as long as it can move

Release date: 2010-08-11

On July 27th, Ms. Wu of Dalian fainted 4 times a night and sent it to the hospital for examination. It was known that the pacemaker battery was out of power, and the pacemaker installed 20 years ago was “strike”.
Ms. Wu is unfortunate. Waiting for her will be surgery to replace the pacemaker, which requires a lot of medical expenses. But she was lucky compared to the person who died because the pacemaker battery was exhausted.
Dr. Li Zhou, a teacher at the School of Biological and Medical Engineering at Beijing University of Aeronautics and Astronautics, said: "In general, the battery life of a pacemaker is 6-8 years. When the battery is exhausted, the patient has a risk of heartbeat and is life-threatening. Replace the pacemaker in time."
Then why does the pacemaker have a "strike" and the heart is finished? Can a pacemaker be self-powered, once and for all?
"Commander" mistakes, the pacemaker top job "the heart has a 'command', control the cardiomyocytes to contract and relax according to a specific procedure, pumping blood for all organs of the body, this 'command' is the sinus node." Li Zhou said.
It is understood that the sinus node is a special small nodule located on the human heart, which can generate electricity automatically and rhythmically. There is a huge transmission "network" in the heart, which constitutes a "bridge" between the sinus node and the cardiomyocytes. The current signals generated by the sinus node are transmitted to various parts of the heart in the order of these conduction tissues, thereby causing myocardial cells. Contraction and relaxation, therefore, the sinus node is known as the highest "command" of the heart beat.
"Once there is a problem with the sinus node, no current can be generated or an abnormal current can be generated. If the cardiomyocytes receive no signal or receive an abnormal signal, they cannot contract and relax normally, and the heart stops beating or abnormally beating, resulting in various physiological reactions. And even die." Li Zhou said, "The pacemaker can replace the sinus node and make the heart beat rhythmically."
Originally, the pacemaker is a pulse generator composed of a battery and a circuit. It can deliver a pulse current of a certain frequency according to a set program. The pacemaker is connected to the heart through the electrode wire, and the pulse current emitted by the pace can be transmitted. Tissue, which eventually leads to contraction of the entire atrium and/or ventricle.
"Not only can the sinus node work be replaced, even if the heart conduction system is broken, the pacemaker can also be 'top job'." Li Zhou said, "You can connect the electrode to the downstream of the conduction system to break the circuit and stimulate this part of the conduction." Tissue-controlled cardiomyocyte contraction and relaxation."
Muscle exercise can be converted into electrical energy. "Battery is one of the keys to a pacemaker. Once a problem occurs, the pacemaker must be replaced. The patient must not only have to undergo surgery again, but also has to bear a lot of money." Wang Zhonglin, a foreign academician of the Chinese Academy of Sciences Said, "So many research institutions are working hard to improve battery life."
The original artificial pacemaker was in the early part of the last century, and the battery was placed outside the body and could only be used in the hospital for a short period of time. After nearly a century of development, pacemaker batteries are getting smaller and longer, and life expectancy is getting longer. At present, most pacemaker batteries can be used for about 10 years, and some even reach 20 years, such as 1988. A paper reported that a nuclear powered pacemaker, using a small amount of sputum, can be used for 20 years, but it is difficult to promote. In recent years, with the development of nanomaterials, in 2005, Wang Zhonglin began to study nano-generators, hoping to use this technology to charge pacemakers.
In the recent issue of Advanced Materials, a new study by Muscle driven in-vivo nanogenerator (Muscle-driven in vivo nanogenerator) from Georgia Institute of Technology was published. The paper was named "Top" by the magazine. Article" (top paper). In the study, they designed a miniature “nano-generator” implanted in animals to extract energy from biological activities and provide electrical energy to sensors implanted in animals (such as pacemakers, implantable blood glucose meters, etc.). .
As one of the authors of the paper, Li Zhou explained that the experiment mainly uses a long strip of nanowires made of a special material to drive the nanowires to bend, straighten or extend shortening through biological activities such as muscle movement. Nanowires produce a piezoelectric effect that causes charge to move. This single nanowire generator (SWG) is visually like a "charge pump" that uses mechanical forces caused by external forces to drive charge motion in the circuit.
“Installing enough nanowires, as long as it can move, can generate electricity.” Li Zhou said, “It is also possible to supply power to the pacemaker.”
Heartbeat power generation, worry about no power failure of the pacemaker "We use the rat's heart beat to drive the SWG and get a steady current." Li Zhou said.
In the experiment, they fixed the SWG with artificial tissue adhesive on the surface of the rat's beating heart. As the heart contracts and relaxes, the SWG is stretched and released while outputting an ac signal to the external circuit. Although a single nanowire can only generate 10 millivolts and 5 picoamps of current, the external output energy is small, but they can increase the number of aligned nanowires, like the series and parallel connections of the battery. A single implantable biomedical device provides sufficient electrical energy. These biomedical devices include blood pressure sensors and glucose sensors, which have moderate current requirements and do not require a continuous current supply.
" Moreover, this study shows that SWG can be used as a viable method of transforming the mechanical energy of living organisms, converting energy in respiratory movements, heart beats, blood flow and blood pressure changes, muscle contractions or some irregular vibrations into "Electric energy." Wang Zhonglin said, "This way, it is possible to achieve the purpose: the pacemaker drives the heartbeat in the process of heartbeat, and the heartbeat in turn charges the pacemaker. Forming the cycle, the pacemaker will not worry about power failure It is."
When it comes to when the technology is applied to the human body, Wang Zhonglin said frankly: "There is still a need for 5-10 years of follow-up experiments. For example, continue to verify the reliability and stability of animals, how many nanowires are assembled to be able to drive. The degree of sinus node, what kind of material is used has no toxic side effects on the human body, etc."

Source: Kexun

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