近期一项调查提示，88%的临床医生愿意掌握对家中患者健康状态指标进行监测的手段，其中多项指标与心力衰竭有关。移动监测器生产商AliveCor公司的创始人和首席科学官David E. Albert博士指出：“随着智能手机技术的进步，这类监测将会越来越有效。”
对于心律，智能手机可检测出心房颤动等心律失常(J. Am. Coll. Cardiol. 2012;59:E726)。Albert博士再次引述了印度孟买一名男子的故事：他的智能手机记录到了无症状性缺血诱导性心律改变，美国俄克拉荷马城和洛杉矶市的临床医生注意到了这一心律失常并通知了这名男子，后者随即前往医院就诊。
Albert博士称，智能手机记录的心电图质量可媲美临床心电图仪采集的12导联心电图。而且有数据提示，日常心电图发现的心房颤动数量位居第二，仅次于置入式设备(Pacing Clin. Electrophysiol. 2007;30:458-62)。“因此，它现在就已经比24 h动态心电监测更优秀了。”
失代偿的发生需要经历一系列变化，从前负荷、自律适应性的增加开始，然后重量、症状逐渐加重并需要住院(Curr. Heart Fail. Rep. 2009;6:287-92)。“我们希望在前负荷、自律适应性增加阶段就能给予早期干预。”节律呼吸8分钟过程中的短期心率变异性，已被证实可预测慢性心力衰竭患者的死亡风险(Circulation 2003;107:565-70)，而智能手机已能胜任监测这一指标的工作。
Albert博士指出，心脏周期中的事件发生时间也可能包含大量信息。这些事件可以通过心脏振动描记来检测，而胸壁振动可通过放置于胸骨前的加速计来检测(Chest 1991;100:991-3)，而且可以与心电图数据相结合，从而得出Tei指数——心脏性能的一种综合性指标(J. Cardiol. 1995;26:135-6)。尽管这些必要的数据可以通过精密的实验室检查来获取(J. Med. Biol. Engineer 2012;32:103-10)，但也可通过放在胸前的智能手机来获得。“我们可以记录等容收缩时间、等容舒张时间和射血时间，并且不仅记录心率、心律和变异性，如今还能获得反映前负荷状态的改良Tei指数。”
By: SUSAN LONDON, Cardiology News Digital Network
SEATTLE – Smartphones may soon be harnessed for monitoring patients with heart failure, offering advantages such as remote assessment and early prediction of decompensation.
A recent survey suggested that 88% of physicians would like to be able to monitor measures of their patients’ health status at home, including many relevant to heart failure. "Those metrics will become more and more available" with smartphone technology, noted Dr. David E. Albert, founder and chief scientific officer of AliveCor Inc., a manufacturer of mobile monitors, including the investigational AliveCor Smartphone System.
The device is an ECG monitor that is in clinical trials and under review by the Food and Drug Administration. A patient uses a smartphone and an app to record a clinical-quality ECG that is securely stored and processed in cloud computing-based server, and can be accessed by a physician anywhere in the world.
The device can evaluate at least three cardiac indices used in the monitoring of heart failure, according to Dr. Albert: cardiac rhythm, heart rate, and heart rate variability.
When it comes to cardiac rhythm, smartphones can be used to detect arrhythmias such as atrial fibrillation (J. Am. Coll. Cardiol. 2012;59:E726). He recounted the story of a man in Mumbai, India, experiencing asymptomatic ischemia-induced rhythm changes that were recorded with a smartphone. Physicians in Oklahoma City and Los Angeles identified the arrhythmia and notified the patient, who then went to his physician.
The ECG obtained with the smartphone has the same quality as a 12-lead ECG obtained with state-of-the-art equipment in the clinic, he said. Also, data suggest that a daily ECG is second only to implanted devices for detecting atrial fibrillation (Pacing Clin. Electrophysiol. 2007;30:458-62). "So it’s better than a 24-hour Holter, even now, and our very intermittent 7-day Holters."
Heart rate, the second index, may be a key therapeutic target in heart failure. Here, too, the smartphone-assessed heart rate is just as accurate as clinically measured heart rate, with sensitivity exceeding 99% for QRS detection (and thus R to R intervals), putting it on par with the 12-lead ECG, according to Dr. Albert.
Heart rate variability, the third index, potentially could be used as an index to guide the need for intervention before progression to decompensated heart failure.
Decompensation develops through a series of changes beginning with increasing preload and autonomic adaptation, and culminating in weight gain, symptoms, and hospitalization (Curr. Heart Fail. Rep. 2009;6:287-92). "Obviously, we want to operate on the left side of this graph, where filling and autonomic adaptation are the places we can intervene early," he noted.
Short-term heart rate variability obtained during 8 minutes of paced breathing has been shown to predict sudden cardiac death in patients having chronic heart failure (Circulation 2003;107:565-70), and smartphones can readily be used for such measurement.
The timing of events during the cardiac cycle may also be informative, according to Dr. Albert. These events can be assessed with seismocardiography, whereby vibrations in the chest are measured with an accelerometer placed on the sternum (Chest 1991;100:991-3) and can be combined with ECG data to derive the Tei index, a global measure of cardiac performance (J. Cardiol. 1995;26:135-6). Although the necessary data can be collected with a somewhat elaborate laboratory setup (J. Med. Biol. Engineer 2012;32:103-10), they can also be obtained easily with a smartphone placed on the chest.
"We can measure isovolumic contraction time, isovolumic relaxation time, and ejection time, and develop in 30 seconds not only rate, rhythm, variability, but now a modified Tei index, an index of performance, and as many papers have said, an index of preload status," he noted.
"With today’s smartphones, which will only get more powerful, we can evaluate cardiac rhythm, or our patients can. They can evaluate their cardiac rate, their heart rate variability, and probably potentially – unproven yet very interesting – their ventricular performance and their preload status, enabling that [information] to be injected into the network, enabling certainly intervention and maybe self-care," Dr. Albert concluded.
A session attendee said that this new technology "sounds very good. But we know even when [clinical devices] are used just to study time intervals, there were a lot of artifacts, and accuracy was not very easily determined. Certainly, with this kind of platform, there must be problems with accuracy and artifact in recordings."
It is still early in development of this technology, Dr. Albert acknowledged. "But understand that we have processing power that’s quite unbelievable. ... What I can tell you is that we can measure these variables; what I can’t tell you is how valuable they are going to be."
Another attendee expressed concern over the vast amount of data that would be generated and then require analysis. "How far are we going to go before we get to the point where we need a different layer besides the physician, the nurses, the PAs? If you are going to swamp us with this much data, there is no way a busy doctor seeing 20 heart patients a day, going to the cath lab, can possibly figure out so much data, what’s important, what’s not," he said.
Recently, the venture capitalist Vinod Khosla put forth a paper calling for fewer doctors and more algorithms, Dr. Albert replied. "I don’t think we will disenfranchise physicians, but I do believe the power of big data will become more and more important for all of us in the management of all our patients," he predicted.
"Apps will be in our pockets as professionals; they will be in our patients’ pockets. And we must figure out how to utilize them to help us deal with major health care issues of the day."
Dr. Albert disclosed that he is member of the board of directors of, a full-time salaried employee of, and an equity shareholder in AliveCor.