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Original Research |

Is Pocket Mobile Echocardiography the Next-Generation Stethoscope? A Cross-sectional Comparison of Rapidly Acquired Images With Standard Transthoracic Echocardiography

Max J. Liebo, MD; Rachel L. Israel, MD; Elizabeth O. Lillie, PhD; Michael R. Smith, MD; David S. Rubenson, MD; and Eric J. Topol, MD
[+] Article and Author Information

From Scripps Clinic, Scripps Translational Science Institute, and West Wireless Health Institute, La Jolla, California.


Note: Drs. Liebo and Israel contributed equally to this article.

Grant Support: In part by Scripps Health and by the National Institutes of Health (Clinical and Translational Science Award to Scripps Translational Science Institute; NIH/NCRR 5 UL1 RR025774).

Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M10-2949.

Reproducible Research Statement:Study protocol and data set: Not available. Statistical code: Available from Dr. Topol (e-mail, etopol@scripps.edu).

Requests for Single Reprints: Eric J. Topol, MD, 3344 North Torrey Pines Court, La Jolla, CA 92037; e-mail, etopol@scripps.edu.

Current Author Addresses: Drs. Liebo, Israel, Smith, and Rubenson: 10666 North Torrey Pines Road, Mail Code SW206, La Jolla, CA 92037.

Drs. Lillie and Topol: 3344 North Torrey Pines Court, Suite 300, La Jolla, CA 92037.

Author Contributions: Conception and design: M.J. Liebo, R.L. Israel, M.R. Smith, D.S. Rubenson, E.J. Topol.

Analysis and interpretation of the data: M.J. Liebo, R.L. Israel, E.O. Lillie, M.R. Smith, D.S. Rubenson, E.J. Topol.

Drafting of the article: M.J. Liebo, R.L. Israel, D.S. Rubenson.

Critical revision of the article for important intellectual content: M.J. Liebo, R.L. Israel, M.R. Smith, D.S. Rubenson, E.J. Topol.

Final approval of the article: M.J. Liebo, R.L. Israel, E.O. Lillie, M.R. Smith, D.S. Rubenson, E.J. Topol.

Provision of study materials or patients: R.L. Israel.

Statistical expertise: R.L. Israel, E.O. Lillie.

Obtaining of funding: E.J. Topol.

Administrative, technical, or logistic support: D.S. Rubenson.

Collection and assembly of data: M.J. Liebo, M.R. Smith.


Ann Intern Med. 2011;155(1):33-38. doi:10.7326/0003-4819-155-1-201107050-00005
Text Size: A A A

Background: A pocket mobile echocardiography (PME) device is commercially available for clinical use, but public data documenting its accuracy compared with standard transthoracic echocardiography (TTE) are not available.

Objective: To compare the accuracy of rapidly acquired PME images with those acquired by standard TTE.

Design: Cross-sectional study. At the time of referral for TTE, ultrasonographers acquired PME images first in 5 minutes or less. Ultrasonographers were not blinded to the clinical indication for imaging or to the PME image results when obtaining standard TTE images. Two experienced echocardiographers and 2 cardiology fellows who were blinded to the indication for the study and TTE results but not to the device source interpreted the PME images.

Setting: Scripps Clinic Torrey Pines and Scripps Green Hospital, La Jolla, California.

Patients: Convenience sample of 97 patients consecutively referred for echocardiography.

Measurements: Visualizability and accuracy (the sum of proportions of true-positive and true-negative readings and observer variability) for ejection fraction, wall-motion abnormalities, left ventricular end-diastolic dimension, inferior vena cava size, aortic and mitral valve pathology, and pericardial effusion.

Results: Physician-readers could visualize some but not all echocardiographic measurements obtained with the PME device in every patient (highest proportions were for ejection fraction and left ventricular end-diastolic dimension [95% each]; the lowest proportion was for inferior vena cava size [75%]). Accuracy also varied by measurement (aortic valve was 96% [highest] and inferior vena cava size was 78% [lowest]) and decreased when nonvisualizability was accounted for (aortic valve was 91% and inferior vena cava size was 58%). Observer agreement was fair to moderate for some measurements among less-experienced readers.

Limitation: The study was conducted at a single setting, there was no formal estimate of accuracy given the small convenience sample of patients, and few abnormal echocardiographic measurements occurred.

Conclusion: The rapid acquisition of images by skilled ultrasonographers who use PME yields accurate assessments of ejection fraction and some but not all cardiac structures in many patients. Further testing of the device in larger patient cohorts with diverse cardiac abnormalities and with untrained clinicians obtaining and interpreting images is required before wide dissemination of its use can be recommended.

Primary Funding Source: National Institutes of Health.

Figures

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Figure 1.
The GE Vscan device (top) and compared with a traditional stethoscope (bottom).

The Vscan device is manufactured by GE Healthcare, Milwaukee, Wisconsin.

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Figure 2.
Pocket mobile echocardiographic images.

LV = left ventricular; LVEDD = left ventricular end-diastolic dimension. A and B. Severely stenotic aortic valve (A) and a normal aortic valve (B). Both images were recorded from a parasternal short-axis view during ventricular systole. C and D. Enlarged (C) and normal (D) LVEDD in the parasternal long-axis view, as measured by electronic calipers built into the software of the ultrasonography device.

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