VOA标准英语2011--Small Electric Jolts Reset Heart Rhythm
时间：2019-01-13 作者：英语课 分类：VOA标准英语2011年(七月)
Small Electric Jolts 1 Reset 2 Heart Rhythm in Animals
For decades, a powerful electric shock has been a standard way to treat someone whose heart has stopped.
But a new study suggests normal heart rhythm can also be restored through a rapid series of safer smaller shocks.
You've probably seen it on TV or in a movie: the patient goes into arrhythmia or her heart stops. The doctor or technician wheels out the defibrillator, applies the paddles, and a powerful electric shock jolts the heart back to a normal rhythm.
Physicist 3 Flavio Fenton of Cornell University says that big shock has a big downside, too.
"If it's external shock like in the movies, you need 280-360 Joules," he says. "That's 1,000 volts 4, 30-40 amps, for about 12 milliseconds. So that's a really large shock. It is very, very strong. It can damage tissue. And it's extremely painful."
Fenton and his colleagues studied the electrical activity of the heart in a state of atrial fibrillation. That's when the heart is beating very fast and at an unsteady pace, so it can't effectively push blood through the body.
Co-lead author Stefan Luther says they theorized that, instead of one big shock, they could restore normal heart rhythm through a rapid series of smaller shocks.
"So pulse-by-pulse you transform the disordered, asynchronously-beating heart into something that's very synchronously 5 beating, and then normal rhythm can take over," Luther says.
After testing the theory on computer models, they demonstrated that it worked on laboratory animals.
Luther says that what they call "low-energy antifibrillation pacing," or LEAP, should be effective against various causes of fibrillation and in different devices, including implantable defibrillators and in automatic defibrillators designed to be used by lay people.
Devices that use the new LEAP method may not be available for years, until after the system is proved in human clinical trials. Current defibrillators may be adapted to deliver a series of smaller shocks.
Fenton and Luther describe their low-energy approach to cardiac defibrillation in the journal Nature.
- He found that out when he got a few terrific jolts, but he wouldn't give up. 被狠狠地撞回来几次后，他发觉了这一点，但他决不因此罢休。
- Some power bars are loaded with carbohydrates or caffeine for quick jolts. 有些能量条中包含大量的碳水化合物和咖啡因，以达到快速提神的效果。
- As soon as you arrive at your destination,step out of the aircraft and reset your wristwatch.你一到达目的地，就走出飞机并重新设置手表时间。
- He is recovering from an operation to reset his arm.他做了一个手臂复位手术，正在恢复。
- He is a physicist of the first rank.他是一流的物理学家。
- The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。
- The floating potential, Vf is usually only a few volts below ground. 浮置电势Vf通常只低于接地电位几伏。 来自辞典例句
- If gamma particles are present, potential differences of several thousand volts can be generated. 如果存在γ粒子，可能产生几千伏的电位差。 来自辞典例句
- Both numbers may slide synchronously in opposite directions. 两数可以同步地向相反方向移位。
- The strong suction motor can synchronously pump the water. 双刷盘设计，清洗效果更强，强劲吸水电机同步抽走污水。