Transmitral Doppler: a new transthoracic contrast method for patent foramen ovale detection and quantification
Andrew J. Kerr, MBChBa,b,
Thomas Buck, MDa,b,
Karin Chia, MBBSa,b,
Chi Ming Chow, MDCMa,b,
Ervin Fox, MDa,b,
Robert A. Levine, MD, FACCa,b and
Michael H. Picard, MD, FACCa,b
a Cardiac Ultrasound Laboratory, Cardiology Division and Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
b Harvard Medical School, Boston, Massachusetts, USA
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Figure 1 Measurement of the maximal patent foramen ovale (PFO) opening diameter from a transesophageal echocardiography image is demonstrated. The interatrial septum lies between the right atrium (RA) and left atrium (LA). The PFO opening diameter (3.4 mm) is the separation between the septum primum and septum secundum (arrows).
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Figure 2 Representative examples of transmitral Doppler bubble scores from 1 to 4 are shown. The top left panel illustrates a bubble score of 1 (1 to 5 bubbles). Three individual bubbles are indicated by asterisks.
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Figure 3 The method of transmitral Doppler (TMD) signal power analysis. Two TMD velocity profiles are shown. (Left panel): Immediately before contrast injection (baseline), (right panel): three beats after RA opacification. Individual bubble signals are indicated by the arrows in the postcontrast profile. An envelope was traced around each TMD profile (illustrated for the baseline profile) allowing exclusion of the valve opening signal present at baseline. The distribution of signal power within the envelope for each profile is plotted in the lower panels. Note that single bubbles in the TMD envelopes correspond to spikes in the power display. The signal power within each envelope was then integrated to give the power time integral (PTI). The postcontrast PTI is normalized by dividing by the baseline power. In this patient the normalized power is 6.
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Figure 4 The relationship between resting transthoracic transmitral Doppler bubble score and transesophageal echocardiography (TEE) measured maximum resting patent foramen ovale (PFO) opening diameter. A good correlation is noted (Kendall’s tau = 0.71). TTE = transthoracic echocardiography.
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Figure 5 The relationship between resting transthoracic transmitral Doppler (TMD) normalized power and transthoracic echocardiography (TEE) measured maximum resting patent foramen ovale (PFO) opening diameter. A good correlation is observed (r2 = 0.72 after log10 transformation).
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