Elsevier

Journal of Nuclear Cardiology

Volume 12, Issue 6, November–December 2005, Pages 687-695
Journal of Nuclear Cardiology

Original article
Onset of left ventricular mechanical contraction as determined by phase analysis of ECG-gated myocardial perfusion SPECT imaging: Development of a diagnostic tool for assessment of cardiac mechanical dyssynchrony

https://doi.org/10.1016/j.nuclcard.2005.06.088Get rights and content

Background

A count-based method using technetium-99m sestamibi electrocardiography-gated myocardial perfusion single photon emission computed tomography imaging has been developed to extract the left ventricular (LV) regional phase of contraction (onset of mechanical contraction [OMC]) throughout the cardiac cycle. This study was performed to develop OMC normal databases and dynamic OMC displays for assessment of cardiac mechanic dyssynchrony.

Methods and Results

LV regional phases were extracted from 90 enrolled normal subjects (45 men and 45 women) by use of the Emory Cardiac Toolbox and then submitted to statistical analysis to generate the normal databases. The LV OMC wave was dynamically propagated over the perfusion polar map by blackening either sequential phase bins or all past phases. The developed OMC normal databases consisted of peak phase (134.5° ± 14.3° for men and 140.2° ± 14.9° for women), phase SD (14.2° ± 5.1° for men and 11.8° ± 5.2° for women), and phase histogram bandwidth (38.7° ± 11.8° for men and 30.6° ± 9.6° for women), skewness (4.19 ± 0.68 for men and 4.60 ± 0.72 for women), and kurtosis (19.72 ± 7.68 for men and 23.21 ± 8.16 for women). Both statistical analysis and dynamic OMC displays were incorporated into a user interface as a diagnostic tool.

Conclusion

The OMC normal databases and dynamic OMC displays should help clinicians evaluate cardiac mechanic dyssynchrony. Prospective clinical trials are needed to validate whether this tool can be used to select patients with severe heart failure symptoms who might benefit from cardiac resynchronization therapy.

Section snippets

OMC Normal Databases

Forty-five men and forty-five women with a less than 5% likelihood of coronary artery disease were enrolled, retrospectively, for the development of the OMC normal databases. Each subject underwent a standard Tl-201/Tc-99m sestamibi dual-isotope rest/exercise stress protocol. The exercise stress imaging was done with ECG-gated SPECT by use of 8 frames per cardiac cycle. The stress short-axis data sets were generated by Butterworth filtering, followed by filtered backprojection reconstruction

Results

The male and female mean normal phase polar maps and histograms are shown in Figure 2. The mean normal phase polar maps showed that the OMC wave starts in the mid anterior and anteroseptal region and propagates quickly to the apex and base. The SD of the phase at the base of the left ventricle was remarkably high because of the error introduced by the automatic determination of the basal slice limit in some studies. The mean normal histograms showed that the OMC phases of a normal poststressed

Discussion

The diagnostic tool described herein includes OMC normal databases and dynamic OMC displays. OMC is an important parameter of cardiac function, in addition to SWT, obtained from ECG-gated SPECT MPI by count-based methods. Count-based methods have been validated by several investigators. Cooke et al,12 from our group, used simulation studies based on a single normal canine study to evaluate the errors associated with the count-based method used in the developed tool. It has been demonstrated

Acknowledgment

Some of the authors (Ernest V. Garcia, Russell D. Folks, C. David Cooke, and Tracy L. Faber) receive royalties for the sale of the Emory Cardiac Toolbox. The other authors have indicated they have no financial conflicts of interest.

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