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Updated: Nov 9, 2025
In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography
Published on: February 16, 2016
Assessment of the conjunctival microcirculation for patients presenting with acute myocardial infarction compared to
Paul F Brennan1,2, Andrew J McNeil3, Min Jing4
1Department of Cardiology, Royal Victoria Hospital, Belfast Health and Social Care Trust, Belfast, UK. paul.brennan@belfasttrust.hscni.net.
Insights
Conjunctival microcirculation, assessed using an iPhone, showed reduced axial velocity and wall shear rate in acute myocardial infarction (MI) patients compared to controls. This suggests potential early microvascular changes in severe cardiovascular disease (CVD).
Area of Science:
- Cardiovascular Disease Research
- Ophthalmology
- Biomedical Engineering
Background:
- Microcirculatory dysfunction is an early indicator in cardiovascular disease (CVD) progression.
- Acute myocardial infarction (MI) represents a severe, late-stage manifestation of CVD.
- The conjunctival microcirculation offers a non-invasive window into systemic microvascular health.
Purpose of the Study:
- To investigate differences in conjunctival microcirculation parameters between acute MI patients and healthy controls.
- To assess the feasibility of using smartphone-based imaging for microcirculatory analysis in MI patients.
- To establish baseline microcirculatory metrics in a severe CVD phenotype.
Main Methods:
- Quantitative assessment of conjunctival microcirculation using an iPhone 6s and slit-lamp biomicroscope.
- Measurement of vessel diameter, axial velocity, wall shear rate, and blood volume flow.
- Comparison of parameters between 59 acute MI patients and 56 healthy controls.
Main Results:
- Conjunctival microcirculation in MI patients exhibited significantly lower axial velocity (0.49 ± 0.17 mm/s vs 0.53 ± 0.15 mm/s) and wall shear rate (145 ± 88 s⁻¹ vs 162 ± 93 s⁻¹) compared to controls (p < 0.001 for both).
- Mean vessel diameter was slightly larger in MI patients (22.32 ± 7.66 μm vs 21.41 ± 7.57 μm, p < 0.001).
- Blood volume flow did not show a significant difference between the groups (p = 0.84).
Conclusions:
- This pilot study demonstrates that smartphone-assisted assessment can detect altered microcirculatory function in patients with acute MI.
- Lower axial velocity and wall shear rate in the conjunctiva may indicate early microvascular impairment associated with severe CVD.
- Further research is warranted to validate these findings and explore their prognostic value in MI patients.
Abstract:
Microcirculatory dysfunction occurs early in cardiovascular disease (CVD) development. Acute myocardial infarction (MI) is a late consequence of CVD. The conjunctival microcirculation is readily-accessible for quantitative assessment and has not previously been studied in MI patients. We compared the conjunctival microcirculation of acute MI patients and age/sex-matched healthy controls to determine if there were differences in microcirculatory parameters. We acquired images using an iPhone 6s and slit-lamp biomicroscope. Parameters measured included diameter, axial velocity, wall shear rate and blood volume flow. Results are for all vessels as they were not sub-classified into arterioles or venules. The conjunctival microcirculation was assessed in 56 controls and 59 inpatients with a presenting diagnosis of MI. Mean vessel diameter for the controls was 21.41 ± 7.57 μm compared to 22.32 ± 7.66 μm for the MI patients (p < 0.001). Axial velocity for the controls was 0.53 ± 0.15 mm/s compared to 0.49 ± 0.17 mm/s for the MI patients (p < 0.001). Wall shear rate was higher for controls than MI patients (162 ± 93 s-1 vs 145 ± 88 s-1, p < 0.001). Blood volume flow did not differ significantly for the controls and MI patients (153 ± 124 pl/s vs 154 ± 125 pl/s, p = 0.84). This pilot iPhone and slit-lamp assessment of the conjunctival microcirculation found lower axial velocity and wall shear rate in patients with acute MI. Further study is required to correlate these findings further and assess long-term outcomes in this patient group with a severe CVD phenotype.
