Changes of central retinal artery blood flow and endothelial function in patients with coronary artery disease

In patients with coronary artery disease (CAD), endothelial function is usually impaired, but the parameters of central retinal artery (CRA) blood flow have not yet been investigated. We designed the study to test the parameters of CRA blood flow and brachial artery flow-mediated dilation (FMD), accompanied by an aim of establishing whether a link may exist between the parameters of CRA blood flow and endothelial function.

Twenty-five subjects were diagnosed as CAD by coronary angiography, and 30 control subjects had normal coronary artery. CRA blood flow and brachial artery FMD were measured noninvasively using high-resolution ultrasound.

In patients with CAD, peak systolic velocity (PSV), end diastolic velocity (EDV), and time velocity integral (TVI) of CRA blood flow were significantly lower (8.75 +/- 2.09 vs. 10.15 +/- 2.16 cm/s, 2.55 +/- 0.73 vs. 3.81 +/- 0.90 cm/s, 5.01 +/- 1.32 vs. 6.27 +/- 1.28 cm/s, respectively, p = 0.019, p < 0.01, p < 0.01), conversely, pulsatility index (PI) and resistance index (RI) were significantly higher (1.28 +/- 0.22 vs. 1.01 +/- 0.20, 0.71 +/- 0.06 vs. 0.62 +/- 0.07, respectively, p < 0.01) when compared with those in normal controls. Meanwhile, brachial artery FMD was decreased in CAD patients (3.91 +/- 1.65 vs. 8.78 +/- 2.92, p < 0.01). After controlling for age, gender, heart rate, and blood pressure, the PSV, EDV, TVI, PI or RI in CRA blood flow were associated with the brachial artery FMD (r = 0.182, 0.372, 0.245, -0.320, or -0.367, respectively, p = 0.205, p = 0.008, p = 0.087, p = 0.023, or p = 0.009).

This study indicates that CRA blood flow is impaired in patients with CAD, and this may partly relate to endothelial dysfunction. Thus, endothelial function is likely to play an important role in the CRA microcirculation.