Department of Cardiology, Royal Victoria Hospital, Belfast Health and Social Care Trust, Belfast, United Kingdom; Biomedical Sciences Research Institute, Ulster University, Coleraine, United Kingdom.
Nanotechnology and Integrated Bioengineering Centre (NIBEC), Ulster University, Jordanstown, United Kingdom.
Microvasc Res. 2021 Jul;136:104167. doi: 10.1016/j.mvr.2021.104167. Epub 2021 Apr 7.
Congenital heart disease (CHD) is the most common live birth defect and a proportion of these patients have chronic hypoxia. Chronic hypoxia leads to secondary erythrocytosis resulting in microvascular dysfunction and increased thrombosis risk. The conjunctival microcirculation is easily accessible for imaging and quantitative assessment. It has not previously been studied in adult CHD patients with cyanosis (CCHD).
We assessed the conjunctival microcirculation and compared CCHD patients and matched healthy controls to determine if there were differences in measured 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. The axial velocity was estimated by applying the 1D + T continuous wavelet transform (CWT). Results are for all vessels as they were not sub-classified into arterioles or venules.
11 CCHD patients and 14 healthy controls were recruited to the study. CCHD patients were markedly more hypoxic compared to the healthy controls (84% vs 98%, p = 0.001). A total of 736 vessels (292 vs 444) were suitable for analysis. Mean microvessel diameter (D) did not significantly differ between the CCHD patients and controls (20.4 ± 2.7 μm vs 20.2 ± 2.6 μm, p = 0.86). Axial velocity (Va) was lower in the CCHD patients (0.47 ± 0.06 mm/s vs 0.53 ± 0.05 mm/s, p = 0.03). Blood volume flow (Q) was lower for CCHD patients (121 ± 30pl/s vs 145 ± 50pl/s, p = 0.65) with the greatest differences observed in vessels >22 μm diameter (216 ± 121pl/s vs 258 ± 154pl/s, p = 0.001). Wall shear rate (WSR) was significantly lower for the CCHD group (153 ± 27 s vs 174 ± 22 s, p = 0.04).
This iPhone and slit-lamp combination assessment of conjunctival vessels found lower axial velocity, wall shear rate and in the largest vessel group, lower blood volume flow in chronically hypoxic patients with congenital heart disease. With further study this assessment method may have utility in the evaluation of patients with chronic hypoxia.
先天性心脏病（CHD）是最常见的活产缺陷，其中一部分患者存在慢性缺氧。慢性缺氧会导致继发红细胞增多症，从而导致微血管功能障碍和血栓形成风险增加。结膜微循环易于成像和定量评估。以前尚未在有发绀的成人 CHD 患者（CCHD）中进行过研究。
我们评估了结膜微循环，并将 CCHD 患者与匹配的健康对照者进行比较，以确定测量的微循环参数是否存在差异。我们使用 iPhone 6s 和裂隙灯生物显微镜获取图像。测量的参数包括直径、轴向速度、壁切变率和血液体积流量。轴向速度通过应用 1D+CWT 连续小波变换来估计。结果适用于所有血管，因为它们没有分为小动脉或小静脉。
共招募了 11 名 CCHD 患者和 14 名健康对照者进行研究。与健康对照组相比，CCHD 患者的缺氧程度明显更高（84% vs 98%，p=0.001）。总共分析了 736 条血管（292 条 vs 444 条）。CCHD 患者和对照组之间的平均微血管直径（D）没有显著差异（20.4±2.7μm vs 20.2±2.6μm，p=0.86）。CCHD 患者的轴向速度（Va）较低（0.47±0.06mm/s vs 0.53±0.05mm/s，p=0.03）。CCHD 患者的血液体积流量（Q）较低（121±30pl/s vs 145±50pl/s，p=0.65），其中直径大于 22μm 的血管差异最大（216±121pl/s vs 258±154pl/s，p=0.001）。CCHD 组的壁切变率（WSR）显著较低（153±27s vs 174±22s，p=0.04）。
这项使用 iPhone 和裂隙灯组合评估结膜血管的研究发现，慢性缺氧的先天性心脏病患者的轴向速度、壁切变率和最大血管组的血液体积流量均较低。进一步研究，这种评估方法可能对评估慢性缺氧患者具有一定的应用价值。
