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Effect of myocardial contractility on hemodynamic end points under concomitant microvascular disease in a porcine
Srikara Viswanath Peelukhana1, Kranthi K Kolli, Massoud A Leesar
1School of Dynamic Systems, Department of Mechanical Engineering, University of Cincinnati, 593 Rhodes Hall, Cincinnati, OH, 45220, USA.
Insights
Coronary diagnostic parameters, pressure drop coefficient (CDP) and lesion flow coefficient (LFC), effectively distinguish coronary artery stenosis levels in microvascular disease (MVD) regardless of heart contractility.
Area of Science:
- Cardiovascular physiology
- Hemodynamics
- Coronary artery disease
Background:
- Microvascular disease (MVD) complicates the assessment of coronary artery stenosis.
- Accurate assessment of coronary artery stenosis is crucial for patient management.
- Existing diagnostic parameters may be affected by varying cardiac contractility.
Purpose of the Study:
- To evaluate coronary diagnostic parameters, specifically pressure drop coefficient (CDP) and lesion flow coefficient (LFC), for distinguishing coronary artery stenosis levels.
- To assess the influence of varying cardiac contractility on these parameters in the presence of MVD.
- To compare CDP and LFC with fractional flow reserve (FFR) in MVD conditions.
Main Methods:
- Coronary artery stenosis (%AS) and MVD were induced in 10 pigs using angioplasty balloons and microspheres.
- Simultaneous measurements of pressure drop, left ventricular pressure, and velocity were recorded.
- Cardiac contractility was assessed using (dp/dt)max and categorized into low (<900 mmHg/s) and high (>900 mmHg/s) groups.
Main Results:
- In the presence of MVD, both CDP and LFC significantly differed between stenosis levels (<50%AS vs. >50%AS) under both low and high contractility conditions (P < 0.05).
- CDP values ranged from 71 to 121 and 18 to 91, while LFC values ranged from 0.10 to 0.19 and 0.08 to 0.25 across stenosis severities and contractility levels.
- Importantly, CDP and LFC were not influenced by cardiac contractility under MVD conditions.
Conclusions:
- CDP and LFC are reliable indicators for assessing coronary artery stenosis severity, even in the presence of MVD.
- These hemodynamic parameters demonstrate independence from cardiac contractility variations in MVD.
- CDP and LFC offer a promising approach for accurate coronary stenosis assessment, similar to FFR, in complex pathophysiological states.
Abstract:
In this study, coronary diagnostic parameters, pressure drop coefficient (CDP: ratio of trans-stenotic pressure drop to distal dynamic pressure), and lesion flow coefficient (LFC: ratio of % area stenosis (%AS) to the CDP at throat region), were evaluated to distinguish levels of %AS under varying contractility conditions, in the presence of microvascular disease (MVD). In 10 pigs, %AS and MVD were created using angioplasty balloons and 90-μm microspheres, respectively. Simultaneous measurements of pressure drop, left ventricular pressure (p), and velocity were obtained. Contractility was calculated as (dp/dt)max, categorized into low contractility <900 mmHg/s and high contractility >900 mmHg/s, and in each group, compared between %AS <50 and >50 using analysis of variance. In the presence of MVD, between the %AS <50 and >50 groups, values of CDP (71 ± 1.4 and 121 ± 1.3) and LFC (0.10 ± 0.04 and 0.19 ± 0.04) were significantly different (P < 0.05), under low-contractility conditions. A similar %AS trend was observed under high-contractility conditions (CDP: 18 ± 1.4 and 91 ± 1.4; LFC: 0.08 ± 0.04 and 0.25 ± 0.04). Under MVD conditions, similar to fractional flow reserve, CDP and LFC were not influenced by contractility.
