Aortic root and valve proportions: an example of the golden ratio?

Calcific aortic stenosis is the most common lesion requiring valve replacement. Transcutaneous procedures (TAVR) are rapidly increasing yet detailed information on aortic valve and root anatomy are sparse.  This study examined gated cardiac CT scans to make observations regarding the size and proportions of the valve leaflets, sinuses of Valsalva, and sinotubular junction. One hundred and fifty gated cardiac CT scans were performed for a variety of clinical indications. Area of each cusp (short axis plane) was measured along with sinus height (from leaflet base to sinotubular junction), sinus width (from central coaptation point to outer sinus edge), annular perimeter, perimeter at mid-sinus level, and perimeter at the sinotubular junction. The right coronary cusp was largest, the left cusp smallest, and the non-coronary cusp intermediate in size. Each cusp was larger in men than women, even after indexing for body surface area.  By contrast, indexed sinus width and height did not differ between genders. No significant differences were noted between races. Annular perimeter did not vary by age while the mid-sinus perimeter and sinotubular junction perimeter increased with age (p=0.01, r2 =0.05 and p=0.002, r2 =0.07).  Interestingly, the ratio of sinus height (average): annular radius was 1.69±0.18, very close to the "golden ratio" of 1.62 found throughout the natural world.  This might be important for proper vortex formation in the sinuses.

Transient Ischemic Dilation Ratio in Regadenoson, Single Isotope Gated Single-photon Emission Computed Tomography Myocardial Perfusion Imaging.

Single isotope 99mTc single-photon emission computed tomography-myocardial perfusion imaging (SPECT-MPI) is the most commonly used protocol for nuclear stress testing. Transient ischemic dilation of the left ventricle (TID) has been considered a specific marker of severe coronary artery disease (CAD). Recent publications have questioned the clinical utility of TID, specifically with regadenoson as a stressor and 4DM-SPECT software for TID analysis. These findings have not been demonstrated using other imaging packages. The goal of our study was to establish the TID threshold in the identification of Multi-vessel CAD using Quantitative Perfusion SPECT (QPS) software. Included in this study are 190 patients that had undergone regadenoson-stress, same day, single-isotope 99mTc MPI and had a coronary angiography within a designated 3-month period. QPS (Cedars-Sinai, LA, CA) automated image analysis software was used to calculate TID ratios which were compared across different CAD categories. Coronary angiograms were reviewed to identify both obstructive and nonobstructive CAD. The mean TID for patients with nonobstructive CAD (n = 91) was 1.02 ± 0.11, and the threshold for TID was 1.24. A receiver operating characteristic curve showed that TID had a poor discriminatory capacity to identify MVD (area under the curve 0.58) with a sensitivity of 3% and a specificity of 97%. In our study with regadenoson MPI in a predominantly African-American population, TID was found to be a poor predictor of MVD using QPS software. The reason is unclear but possibly related to the significant decline in the prevalence of severe CAD in the area where our study took place.