300.20 Non-invasive Quantification of Disturbed Coronary Blood Flow Using Pressure Drop and Vorticity

Background: Evaluating the severity of peripheral artery lesions is challenging. Image-based blood flow modeling from peripheral Computed Tomographic Angiography (pCTA) may provide a non-invasive method to determine the hemodynamic significance of lesions. This pilot study evaluates the performance of pCTA-based blood flow modeling in diagnosing functionally significant peripheral lesions in comparison with Digital Subtraction Angiography (DSA). Methods: Ten patients undergoing DSA and pCTA were included. The peripheral arteries were divided into 8 segments per extremity and stenosis severity was graded by visual estimation from DSA. Each segment was graded 0 to IV (normal, mildly-stenotic, moderately-stenotic, severely-stenotic, occluded) or non-evaluable. Independent from DSA review, a Resting Pressure Drop (RPD) and an Exercise Pressure Drop (ExPD) for each segment was calculated from pCTA-based blood flow modeling. A functionally significant (FS) lesion was defined as grade III or IV by DSA and RPD > 5 mmHg from pCTA-based modeling. Analysis was repeated with an ExPD > 20 mmHg. Sensitivity, specificity and accuracy were calculated for RPD > 5 mmHg and ExPD > 20 mmHg using DSA as the standard. Results: Mean age was 52±16 years, 4 patients were male, 8 patients presented with critical limb ischemia, mean ankle brachial index was 0.60±0.29, and 66 arterial segments were available for both assessment methods. Twenty-two segments had FS lesions by DSA. Using an RPD > 5 mmHg, sensitivity was 80%, specificity was 85% and accuracy was 79%. Using an ExPD > 20 mmHg, sensitivity was 84%, specificity was 89% and accuracy was 88%. Conclusion: Use of a resting pressure drop > 5 mmHg and an exercise pressure drop > 20 mmHg, measured by blood flow modeling from CT angiography, can accurately identify functionally significant stenosis in patients with peripheral vascular disease. This information motivates the need for a larger-scale prospective imaging trial to further validate this novel non-invasive approach.

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Modelling coronary flow after the Norwood operation: Influence of a suggested novel technique for coronary transfer

Global Cardiology Science and Practice ◽

10.21542/gcsp.2018.7 ◽

2018 ◽

Vol 2018 (1) ◽

Author(s):

Mohammed K Al-Jughiman ◽

Maryam A Al-Omair

Keyword(s):

Blood Flow ◽

Pressure Drop ◽

Coronary Blood Flow ◽

Aortic Root ◽

Coronary Flow ◽

Fluid Dynamic ◽

Survival Outcomes ◽

Transfer Model ◽

Left Main

Background: The dynamic behavior of the aortic sinuses has an important function in the specific characteristics of coronary blood flow. Several publications have confirmed suboptimal myocardial perfusion after the Norwood procedure. Our study was undertaken to confirm four hypotheses. First, we hypothesized that there is more resistance to coronary flow due to coronary attachments to hypoplastic aortic root and sinuses. Also, as the amalgamation of the ascending aorta with the pulmonary artery occurs above the aortic root, the coronary blood flow is not fully in antegrade pattern. Second, performing the Norwood with our modification i.e., coronary transfer to the well-developed sinuses of the pulmonary root will result in less resistance to flow and a full antegrade flow pattern. This may eventually improve the long term ventricular and survival outcomes. Third, our modification is applicable to all procedures where the pulmonary root supplies the systemic circulation e.g., Norwood, Damus–Kaye–Stansel (DKS), and Yasui operations, whether applied to single or biventricular repair. Fourth, with our modification, the effect of the type of shunt; Sano vs. Blalock Taussig (BT shunt) on the coronary flow after the Norwood will be mitigated. This will give the surgeon more freedom to which shunt to use, and may make the surgeon keener to perform the BT shunt in order to avoid the ventricular scar associated with the Sano shunt which will negatively impact the ventricular function. Methods: Computational fluid dynamic (CFD) simulations were performed to evaluate flow streamlines and to quantify flow distribution and total pressure drop in the coronary branches in both Norwood (pre-transfer) and modified Norwood (post-transfer) models. Comparisons between the two models were performed. Results: The systolic flow rate in all coronary branches was higher in the post-transfer model in the proportions of: left main 5%, left anterior descending (LAD) 6%, left circumflex (LCx) 3.5%, and right coronary artery (RCA) 7.2% higher flow rates. In diastole, pressure drop from the aortic inlet to distal left main and distal right main was substantially less in the post-transfer model. Conclusion: Post-transfer model has produced more favorable coronary hemodynamics in all coronary branches. As a result, performing our modification could potentially improve the long term ventricular and survival outcomes.

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