使用固有频率方法通过无创iPhone测量左心室射血分数
Noninvasive iPhone Measurement of Left Ventricular Ejection Fraction Using Intrinsic Frequency Methodology.
作者信息
Pahlevan Niema M, Rinderknecht Derek G, Tavallali Peyman, Razavi Marianne, Tran Thao T, Fong Michael W, Kloner Robert A, Csete Marie, Gharib Morteza
机构信息
1Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA.2Advanced Imaging and Spectroscopy Center, Huntington Medical Research Institutes, Pasadena, CA.3Avicena LLC, Los Angeles, CA.4Computing and Mathematical Sciences, California Institute of Technology, Pasadena, CA.5Medical Engineering Department, California Institute of Technology, Pasadena, CA.6Division of Cardiovascular Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA.7Cardiovascular Research Institute, Huntington Medical Research Institutes, Pasadena, CA.8Department of Anesthesiology, Keck School of Medicine, University of Southern California, Los Angeles, CA.9Graduate Aerospace Laboratory, California Institute of Technology, Pasadena, CA.
出版信息
Crit Care Med. 2017 Jul;45(7):1115-1120. doi: 10.1097/CCM.0000000000002459.
OBJECTIVE
The study is based on previously reported mathematical analysis of arterial waveform that extracts hidden oscillations in the waveform that we called intrinsic frequencies. The goal of this clinical study was to compare the accuracy of left ventricular ejection fraction derived from intrinsic frequencies noninvasively versus left ventricular ejection fraction obtained with cardiac MRI, the most accurate method for left ventricular ejection fraction measurement.
DESIGN
After informed consent, in one visit, subjects underwent cardiac MRI examination and noninvasive capture of a carotid waveform using an iPhone camera (The waveform is captured using a custom app that constructs the waveform from skin displacement images during the cardiac cycle.). The waveform was analyzed using intrinsic frequency algorithm.
SETTING
Outpatient MRI facility.
SUBJECTS
Adults able to undergo MRI were referred by local physicians or self-referred in response to local advertisement and included patients with heart failure with reduced ejection fraction diagnosed by a cardiologist.
INTERVENTIONS
Standard cardiac MRI sequences were used, with periodic breath holding for image stabilization. To minimize motion artifact, the iPhone camera was held in a cradle over the carotid artery during iPhone measurements.
MEASUREMENTS AND MAIN RESULTS
Regardless of neck morphology, carotid waveforms were captured in all subjects, within seconds to minutes. Seventy-two patients were studied, ranging in age from 20 to 92 years old. The main endpoint of analysis was left ventricular ejection fraction; overall, the correlation between ejection fraction-iPhone and ejection fraction-MRI was 0.74 (r = 0.74; p < 0.0001; ejection fraction-MRI = 0.93 × [ejection fraction-iPhone] + 1.9).
CONCLUSIONS
Analysis of carotid waveforms using intrinsic frequency methods can be used to document left ventricular ejection fraction with accuracy comparable with that of MRI. The measurements require no training to perform or interpret, no calibration, and can be repeated at the bedside to generate almost continuous analysis of left ventricular ejection fraction without arterial cannulation.
目的
本研究基于先前报道的动脉波形数学分析方法，该方法可提取波形中隐藏的振荡，即我们所称的固有频率。本临床研究的目的是比较通过固有频率无创得出的左心室射血分数与通过心脏磁共振成像（cardiac MRI，心脏磁共振成像为测量左心室射血分数最准确的方法）获得的左心室射血分数的准确性。
设计
在获得知情同意后，受试者在一次就诊时接受心脏磁共振成像检查，并使用苹果手机摄像头对颈动脉波形进行无创采集（使用一款自定义应用程序采集波形，该程序根据心动周期中的皮肤位移图像构建波形）。使用固有频率算法对波形进行分析。
地点
门诊磁共振成像设施。
受试者
能够接受磁共振成像检查的成年人由当地医生转诊或因当地广告自荐而来，包括经心脏病专家诊断为射血分数降低的心力衰竭患者。
干预措施
使用标准心脏磁共振成像序列，定期屏气以稳定图像。为尽量减少运动伪影，在使用苹果手机测量时，将苹果手机摄像头固定在颈动脉上方的支架中。
测量与主要结果
无论颈部形态如何，所有受试者均在数秒至数分钟内采集到颈动脉波形。共研究了72例患者，年龄在20至92岁之间。分析的主要终点是左心室射血分数；总体而言，苹果手机测得的射血分数与磁共振成像测得的射血分数之间的相关性为0.74（r = 0.74；p < 0.0001；磁共振成像测得的射血分数 = 0.93×[苹果手机测得的射血分数] + 1.9）。
结论
使用固有频率方法分析颈动脉波形可用于记录左心室射血分数，其准确性与磁共振成像相当。这些测量无需培训即可进行或解读，无需校准，并且可以在床边重复进行，以在无需动脉插管的情况下对左心室射血分数进行几乎连续的分析。
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