| BackgroundEssential hypertension is one of cardiovascular diseases with the highest incidence. The Chinese Hypertension Prevention Guide (2010) pointed out there were more than 0.2 billion hypertensive patients in our country, one out of five adults suffered from hypertension and the number of hypertensive patients increases 10 million per year. Most of them are essential hypertensive patients. In our country, the awareness rate of hypertension, the treatment rate and the control rate which are all lower than those from developed countries. As a result, some hypertensive patients suffered from target organ damage when they came to see doctors. Even the hypertensive patients with a controlled blood pressure still have the progress in target organ damage, such as kidney failure and stroke, which is a key issue to influence seriously the outcome of treatment for hypertension and its complications. Making clear the mechanism underlying target organ damage of essential hypertensive will promote the prevention and treatment of hypertension. The increase of the peripheral circulation resistance is the main reason for the increase of blood pressure in hypertensive patients, and the microcirculation plays a key role in the increase of peripheral vascular resistance. Research data shows that alteration in microcirculation morphological and functional existed both in experemental animal and hypertensive patients. An attention has been paid to microcirculation alteration in the prevention, treatment, and prognosis evaluation of patients from essential hypertension. Microvascular dysfunction is the main reason for target organ damage in patients with controlled blood pressure and a new target for the treatment of target organ damage induced by hypertension.The microcirculation insists of three parts:hematological microcirculation, lymphatic microcirculation and interstitial microcirculation. Among them, hematological microcirculation is the main site influenced by hypertension, which consists of arteriole, venule, and capillary network. The hypertension-induced microvascular dysfunction exists in multi-organs, including brain, kidney, heart, the target organs of hypertension. The main morphological change of microvascular dysfunction is as follows:(1) capillary rarefaction, (2) the tortuosity and destruction of arteriole, venule, and capillary. (3) erythrocytes aggregation. The dysfuction of microcirculation is mainly reflected as the change of microvascular pressure and the decrease of blood perfusion. Although other methods such as magnetic resonance (MR), intravascular ultrasound and ultrasound contrast indicated indetectly the change of microcirculation, it is still need the direct, non-invasive, and quantitative approaches to detect the microcirculation in clinical settings. Nailfold and conjunctival capillaroscopy capillaroscopy show us derectely, to some extent, the change of microcirculation in patients with the characteristics of non-invasivion, good compliance and convenience to observe the curative effect and follow-up. Studies showed that the microcirculation alteration was almost the same between conjunctival and retinal microcirculation. Recently laser doppler flowmetry is emerging, which is a new approach to detect the microcirculatory fuction by monitering blood flow before and after local heating, small artery pressure in finger and toe tip. The comprehensive,quantitative analysis of these non-invasived results may indicat the morphology and function of microcirculation in the body. It is notable that hypertension also accompanies with other cardiovascular risk factors. However, there is no report to illustrate the change of microvascular morphology and function in hypertensive patients with different risk stratification. It is important theoreticaly and clinically to demonstrate the microvasculation alteration in essential hypertensive patients with different risk stratification for the diagnosis, prognosis and curative evaluation of essential hypertension and its organ damage is.ObjectiveThe alteration of microvascular morphology and function in essential hypertensive patients with different risk stratification was investigated, to provide a new target to diagnosis, prognosis and curative evaluation of essential hypertension and organ damage from the point of view of microcirculation.Methods1. Study objects was selected according to the inclusion and exclusion criteria. This study collected hypertensive outpatients in accordance with the total standards of the essential hypertension and healthy volunteers in the General Hospital of PLA from Aprile,2014 to Febrary,2015.2. Microcirculation detection2.1 Nailfold capillaries in the dorsal skin of the left fourth finger were visualized using a stereomicroscope (ZL-104; Xuzhou, China) and analysed by microcirculation image analysis software. The clearity of capillaries and perivascular circumstance were visualized with magnification of 20×. The microvascular morphology and blood flow were visualized with magnification of 50×.2.2 Conjunctival capillaries in the bulbar conjunctiva were visualized using a stereomicroscope (ZL-104; Xuzhou, China) and analysed by microcirculation image analysis system. The clearity of capillaries and perivascular circumstance were visualized with a magnification of 20×. The microvascular morphology and blood flow were visualized with a magnification of 50×.2.3 Laser doppler flowmetry (Perimed, Sweden) was used to monite microvascular function by detecting skin temperature, microvascular blood flow, small arterial pressure and mean brachial index.Statistical treatmentSPSS 17.0 statistics software was used for data analysis.The results were presented as the mean±SD. Significant differences among groups were assessed by one-way analysis of variance (ANOVA) followed by least-significant difference (LSD). Categorical data was dealed with the chi square test. P-values less than 0.05 were considered stastically significant.Results1. Compared with the healthy control group, patients in moderate and higher (including intermediate) risk groups, the nailfold microcirculation was showed as poor vision clarity, the decreasing number of capillary loops, the increase of the abnormal capillary loops/total loops ratio, the smaller diameter of input branch, a slow flow of blood, an aggregation of erythrocytes and the increase of perivascular infiltration. The differences were statistically significant (P<0.05).Those changes above gradually aggravated with the increase of the risk factor stratification of hypertension.2. Compared with the healthy control group, conjunctival microcirculation in patients from low risk group showed sparse grid structure, capillary rarefaction and the smaller diameter of small veins. The differences were statistically significant (P<0.05). The alternation of conjunctival microcirculation in moderate and higher (including intermediate) risk groups was contained with morphology, blood flow and the surrounding of microvessels. The morphological changes mainly showed the decreasing definition, capillary rarefaction, the smaller diameter of arterioles and venules, as well as the increasing number of uneven thickness microvessels. Moreover, it showed the emergence of grid structure, capillary hemangioma, cystically dilated and ischemic region. The blood flow changes were mainly reflected as the microvascular blood flow velocity, the erythrocyte aggregation, as well as the increase of capillary exudation and hemosiderin deposition. With the increasing risk stratification of hypertension, the proportion of grid structure in bulbar conjunctival microvessels was gradually increased, capillary rarefaction was gradually aggravated, microvascular blood flow velocity gradually slowed down, and the aggregation of erythrocytes was gradually aggravated. The difference was statistically significant (P<0.05).3. Compared with healthy control group, all the hypertension patients showed no statistical differences in the temperature of dorsal skin on left ring finger, baseline of microvascular perfusion, and arterial blood pressures of left ringer finger (P>0.05). Also, There were no statistical differences among low risk, median risk and high risk hypertension patients and healthy group. Microvascular perfusion in very high risk hypertension patients was 33% lower than that in healthy control group (P<0.05). A significant difference in lower left finger brachial index was observed in high risk hypertension group (0.81±0.17 vs 0.95±0.04, P<0.05), while left finger brachial index in low risk, median risk and very high risk hypertensive patients were 0.85±0.1,0.9±0.1, 0.88±0.15 respectively.Conclusion1. The alternations of nailfold and conjunctival microcirculation were related with risk factor stratification in patients with essential hypertension.2. Microvascular dysfunction was found in intermediate and higher risk group (including intermediate) in patients with essential hypertension.3. Nailfold and conjunctival capillaroscopy, and LDF can be used to evalute the nperipheral microcirculation in patients with essential hypertension. |
PDF Full Text Request