Will iPhone 12 interfere with pacemakers? This is just common sense, not news

Apple warns iPhone 12 not to be placed near pacemakers because MagSafe accessories may interfere with them. This statement has aroused concern. Can mobile phones really interfere with pacemakers?

Written by reporter Zhao Ling Edited by Liu Zhao

New Media Editor/Fang Yongzhen

Interview experts:

Zhao Zhanyong (Deputy Chief Physician, Department of Cardiology, Beijing Anzhen Hospital)

Electronics enthusiasts and "Apple fans" must be familiar with the iPhone 12. As Apple's masterpiece in 2020, the iPhone 12 has been sought after by a large number of "Apple fans" since its first sale.

In January this year, iPhone 12 was on Weibo's hot search again, but this time the entry was a little sensational: "Apple warns iPhone 12 not to get close to pacemakers because its MagSafe accessories may interfere with pacemakers." Under this hot search, some netizens commented that iPhone 12 "not only costs money but also costs lives." What is the truth?

(Picture from the Internet)

Pacemakers are extremely sensitive to magnetic signals

It is understood that the origin of this topic is that Apple wrote in a support document updated on January 23 that iPhone 12 and MagSafe accessories should not be placed too close to medical devices such as implanted pacemakers, and it is recommended to keep a distance of 15cm to 30cm. Previously, a report in a medical journal pointed out that doctors found that iPhone 12 would put the device into a "pause" state when it was close to an implanted defibrillator.

In fact, this is not a piece of “news”. Perhaps it would be more accurate to call it “fact” or “common sense”. Why? Let’s first understand the other protagonist of this incident: the pacemaker.

Originally, the heart has its own natural pacemaker, the sinoatrial node, which acts like a generator, transmitting rhythmic electrical impulses to other parts of the heart, which in turn causes the atria and ventricles to contract and produce heartbeats. A normal human heart needs to beat 60 to 100 times per minute to ensure normal blood supply to all organs of the body. Beating too fast or too slow is abnormal and requires treatment.

Zhao Zhanyong, deputy chief physician of the Department of Cardiology at Beijing Anzhen Hospital, explained: "Some patients have bradycardia, and the frequency of the electrical signals from the sinoatrial node is slower than that of normal people, or the electrical signals from the sinoatrial node cannot reach other parts of the heart smoothly, which can cause dizziness, blackouts, and even syncope. At this time, we need to install an 'artificial generator' for the patient, that is, a pacemaker, to help the heart emit pulses, which are transmitted to the atria and ventricles through the electrode wires, helping the patient's heart to restore its normal frequency of beating."

▲Chest X-ray image of the patient after the pacemaker was implanted (Photo courtesy of Zhao Zhanyong)

Today's pacemakers have been developed very maturely. They are generally only the size of a matchbox and weigh about the same as two No. 7 batteries. Zhao Zhanyong introduced that there are many types of pacemakers, and different types can be selected according to the different medical conditions of each patient. For patients with bradycardia, single-chamber pacemakers and dual-chamber pacemakers can be implanted; for patients with heart failure, three-chamber pacemakers can be implanted; for patients with too fast heart rates, such as ventricular tachycardia and ventricular fibrillation, defibrillators can be implanted.

However, all types of pacemakers have something in common, which is that they are susceptible to electromagnetic interference. "Implantable pacemakers are very sensitive to external signals, especially strong electrical and magnetic signals," said Zhao Zhanyong. "We have observed that when a magnet is placed close to the skin where the pacemaker is implanted, the magnetic switch in the pacemaker will turn on and its output frequency will change to the magnetic frequency. Generally, it will become 100 times per minute, which will cause the patient to feel anxious and other discomfort symptoms. After removing the magnet, the pacemaker will return to its normal working frequency, usually 60 times per minute."

At this point, it is not difficult to guess why the iPhone 12 cannot be too close to the pacemaker - the mobile phone must contain many magnetic components, such as the camera's focus module, speakers, etc., which contain magnets of varying numbers and magnetic forces. Obviously, they will affect the pacemaker and cause it to malfunction.

According to a report by China News Service in earlier years, there was a patient in Guangzhou who was equipped with a permanent pacemaker. After borrowing a friend's mobile phone to make a call for a while, he suddenly felt his heartbeat was getting faster and slower. He then rushed to a nearby hospital and was able to escape danger.

Therefore, it can be regarded as common sense in the medical field that devices that produce electromagnetic interference need to be kept away from medical devices. Every patient will be told to "keep the pacemaker away from magnetic objects, including electronic devices" when a pacemaker is installed. This is no longer "news".

▲Basic structure of a pacemaker (Photo source: Department of Cardiology, Peking University First Hospital)

iPhone 12's magnetic attraction technology adds a magnet array

The distance between a mobile phone and a pacemaker can be considered "common sense". People who are used to reading the manuals of electronic products may find that as early as the iPhone 3GS era, Apple had stated that the mobile phone should be kept at least 15 cm (6 inches) away from the pacemaker, and the mobile phone should not be placed in the chest pocket to prevent interference with the pacemaker. The manuals of other brands of mobile phones also have explanations of relevant terms.

But the iPhone 12 is indeed special compared to other mobile phones because it comes with MagSafe accessories. MagSafe is Apple's magnetic connection technology that can be attached to the back of the phone by magnetic attraction to identify accessories and perform wireless charging. In order to be compatible with it, the entire iPhone 12 series of mobile phones has a circular magnet array around the central wireless charging coil to ensure that the wireless charger can be aligned with the back of the iPhone for faster charging.

According to Zhao Zhanyong, the effect of magnetism on pacemakers is related to the size of the magnetic force and the distance. The greater the magnetic force and the closer the distance, the easier it is to be affected. Therefore, the newly added magnetic accessories of iPhone 12 will undoubtedly greatly enhance the effect on pacemakers.

In this case, Zhao Zhanyong recommends that patients with implanted pacemakers must strictly control the distance requirement of more than 15cm when using mobile phones, especially iPhone12. "Because the pacemaker is implanted under the clavicle, it is relatively close to the head. Therefore, when answering the phone, be careful not to answer the phone on the same side - if the pacemaker is installed on the left, answer the phone on the right, and vice versa."

According to Apple's official recommendations, in addition to keeping the iPhone 12 more than 15 cm away from medical devices during daily use, when using wireless charging, it is necessary to keep a distance of more than 30 cm from medical devices such as pacemakers.

Electromagnetic signals in life are much more dangerous than mobile phones

In fact, for patients with pacemakers, there are countless items in life that are more dangerous than mobile phones. Induction cookers, induction pots, old radios, magnetic therapy sticks... The electromagnetic signals of these items are higher than those of mobile phones, and they are easily ignored.

Other details of life that we take for granted also need special treatment, such as security checks at airports and subways. Every patient with a pacemaker has his or her own pacemaker ID card. By showing this card, they can be asked to avoid the security machine approaching the pacemaker, otherwise it is likely to cause pacemaker failure. In addition, power plants, high-voltage wires, transformer boxes, etc. can generate strong electromagnetic signals, which will seriously interfere with the working state of the pacemaker and cause greater harm.

(Photo source/CCU of Yuncheng Central Hospital, Graphics Editor/Qi Xi)

In order to reduce the impact on patients, pacemakers are also being optimized. Zhao Zhanyong said: "After implanting a traditional pacemaker, the patient cannot undergo MRI because it is a strong magnetic field environment. However, more and more patients are now implanted with MRI-compatible pacemakers. This type of pacemaker can be adjusted to an anti-interference mode by professionals when necessary, which is equivalent to opening a protective cover inside the pacemaker to ensure that the pacemaker's battery and wires are not affected by MRI." Of course, this mode is extremely power-consuming and can only be turned on under special circumstances, and cannot be kept on in daily life.

In his clinical career, Zhao Zhanyong has indeed encountered a case of pacemaker failure: "A patient came to the hospital about a month after the pacemaker was installed and said that the pacemaker was not working. At that time, we replaced the pacemaker with a new one and mailed the faulty pacemaker to the manufacturer for analysis. We found that during that month, the pacemaker was once subjected to strong electromagnetic interference, which eventually caused the pacemaker to malfunction."

Fortunately, the patient discovered the problem with the pacemaker in time, and his reliance on the pacemaker was limited, so it was fine after a timely replacement. Zhao Zhanyong suggested that if patients with pacemakers are exposed to strong electromagnetic signals and experience physical discomfort, they should immediately stay away from electromagnetic interference sites and go to the hospital to check whether the pacemaker function has been interfered with to ensure their own safety.

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