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Int J Cardiol. 2013 Sep 30;168(2):1220-8. doi: 10.1016/j.ijcard.2012.11.059. Epub 2012 Dec 11.

Evidence-based recommendations for PISA measurements in mitral regurgitation: systematic review, clinical and in-vitro study.

Author information

1
International Centre for Circulatory Health, National Heart and Lung Institute, Imperial College, 59-61 North Wharf Road, London W21LA, UK. Electronic address: michela.moraldo@gmail.com.

Abstract

BACKGROUND:

Guidelines for quantifying mitral regurgitation (MR) using "proximal isovelocity surface area" (PISA) instruct operators to measure the PISA radius from valve orifice to Doppler flow convergence "hemisphere". Using clinical data and a physically-constructed MR model we (A) analyse the actually-observed colour Doppler PISA shape and (B) test whether instructions to measure a "hemisphere" are helpful.

METHODS AND RESULTS:

In part A, the true shape of PISA shells was investigated using three separate approaches. First, a systematic review of published examples consistently showed non-hemispherical, "urchinoid" shapes. Second, our clinical data confirmed that the Doppler-visualized surface is non-hemispherical. Third, in-vitro experiments showed that round orifices never produce a colour Doppler hemisphere. In part B, six observers were instructed to measure hemisphere radius rh and (on a second viewing) urchinoid distance (du) in 11 clinical PISA datasets; 6 established experts also measured PISA distance as the gold standard. rh measurements, generated using the hemisphere instruction significantly underestimated expert values (-28%, p<0.0005), meaning r(h)(2) was underestimated by approximately 2-fold. du measurements, generated using the non-hemisphere instruction were less biased (+7%, p=0.03). Finally, frame-to-frame variability in PISA distance was found to have a coefficient of variation (CV) of 25% in patients and 9% in in-vitro data. Beat-to-beat variability had a CV of 15% in patients.

CONCLUSIONS:

Doppler-visualized PISA shells are not hemispherical: we should avoid advising observers to measure a hemispherical radius because it encourages underestimation of orifice area by approximately two-fold. If precision is needed (e.g. to detect changes reliably) multi-frame averaging is essential.

KEYWORDS:

Echocardiography; Mitral regurgitation; PISA method

PMID:
23245796
PMCID:
PMC3819991
DOI:
10.1016/j.ijcard.2012.11.059
[Indexed for MEDLINE]
Free PMC Article

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