【作者】 张楠；

【导师】 范占明；

【作者基本信息】 首都医科大学 ， 影像医学与核医学， 2013， 硕士

【摘要】 目的利用磁共振成像技术评价原发性高血压患者主动脉管腔顺应性和血液动力学状态，探讨两者相关性及其在原发性高血压发病机制中的作用。方法前瞻性选择经临床证实诊断为原发性高血压的中年患者60例入组。其中单纯收缩期高血压（收缩压≥140mmHg；舒张压＜90mmHg）A组30例（平均年龄55.5±3.1岁，男性14例）、非单纯收缩期高血压（收缩压≥140mmHg；舒张压≥90mmHg）B组30例（平均年龄52.6±5.9岁，男性15例）。无高血压病史者（收缩压＜140mmHg；舒张压＜90mmHg）30例（平均年龄51.7±5.8岁，男性15例）作为对照组C。所有受检者均行全主动脉磁共振检查，包括真实稳态快速回波（True Fast Image with Steady-state Precession，TrueFISP）序列扫描，除外主动脉疾患。并利用相位对比磁共振血管成像（Phase Contrast MRA，PC-MRA）序列分别采集3个主动脉层面一个心动周期内局部血液动力学参数信息：①升主动脉肺动脉分叉水平；②降主动脉肺动脉分叉水平；③腹主动脉平较低一支肾动脉下1cm水平。并于相应层面行快速电影成像（Cine）序列扫描，同时记录受检者血压值。对图像数据进行定量分析，测量各层面一个心动周期内管腔的平均横断面积、平均血流速度、平均血流量和净流量，并计算局部管腔的绝对及相对顺应性。比较（1）同一受试者不同部位主动脉管腔顺应性参数、平均血流速度、平均血流量、净流量的差异；（2）3组受试者相同主动脉层面局部管腔顺应性参数、平均血流速度、平均血流量、净流量的差异；（3）主动脉管腔顺应性参数与血压及血流指标（平均血流速度、平均血流量和净流量）间的相关性。结果高血压组（A组、B组）患者在所选各层面主动脉管腔绝对顺应性（Compliance，C）、相对顺应性（Distensibility，D）均低于对照组（P<.05）；相应部位管壁弹性模量（Young s modulus，E）均高于对照组（P<.05）。升主动脉至腹主动脉，主动脉管腔D呈升高趋势，C及E呈减低趋势（P<.05），B组患者腹主动脉层面E反常升高。最高主动脉平均流速值发生于胸降主动脉层面。峰值流速、前向流量随升主动脉至腹主动脉呈减低趋势，返流量呈升高趋势。C组受检者主动脉血流峰值流速、平均流速均高于相应层面A组及B组流速值，其中胸降主动脉峰值流速差异具有统计学意义。升主动脉返流均发生于舒张期早期，B组发生率最高（12/30，40.0%），C组最少（2/30，6.7%）（P<.05）。胸降主动脉层面，B组主动脉返流发生率最高（29/30，96.7%），且全舒张期主动脉返流发生率（9/30，30.0%）最高，C组最少（20/30，66.7%；0/30，0%）（P<.05）。腹主动脉层面，B组全舒张期返流发生率（15/30，50.0%）最高，但差别无明显统计学意义。SBP及PP与主动脉各层面C、D呈轻-中度负相关；与E呈轻度正相关。DBP与腹主动脉层面D、E呈轻度相关性。结论本研究发现主动脉顺应性减低可以引起主动脉血流减慢，是主动脉管腔内流体压力升高的重要原因。同时主动脉返流的产生及存在时相延长是舒张压升高的重要原因，其原因可能是远端主动脉（腹主动脉）顺应性异常减低。因此，主动脉顺应性减低是高血压产生重要机制之一，保持及恢复主动脉顺应性对于临床预防及治疗高血压具有重要意义。更多还原

【Abstract】 Objective:To observe the local aortic stiffness parameters and hemodynamic states in primaryhypertensive patients with MRI. The correlation between them was investigated. Andthe effect of aortic stiffness on hemodynamics changes and primary hypertensivepathogenesis were discussed.Material and methods:Consecutively60clinical diagnosed primary hypertensive patients were divide into2groups: group A (isolated systolic hypertension, ISH; SBP≥140mmHg; DBP＜90mmHg)(average age55.5±3.1Y, male14), group B(non-isolated systolichypertension, NISH; SBP≥140mmHg; DBP≥90mmHg)(average age52.6±5.9Y,male15).30subjects with no hypertensive(SBP＜140mmHg; DBP＜90mmHg) wereenrolled as control group C(average age51.7±5.8Y, male15). All the subjectsunderwent MRI examination and BP was recorded simultaneously. During MRIexamination, TrueFISP sequence, PC-MRA sequence and Cine sequence wereperformed. The cross-sectional images of aorta for PC-MRA and Cine sequences wereacquired at the following3locations:①ascending aorta at pulmonary bifurcationlevel;②descending aorta at pulmonary bifurcation level;③abdominal aorta at1cmdistal to the lowest renal artery. At the aortic levels, the average cross-sectional area ofthe lumen, the average flow velocity, the average blood flow and the net flow, andcalculate partial lumen of the absolute and relative compliance were measured in onecardiac cycle with quantitative analysis of the image data.(1) Average lumencompliance, mean flow velocity, the average blood flow, the net flow were comparedat the different aortic levels.(2) Differences among3groups were discussed inaverage lumen compliance, mean flow velocity, average blood flow, net flow with corresponding aortic level.(3) Correlation between of the aortic lumen compliancewith blood pressure and blood flow index (mean flow velocity, average blood flowand net flows) were calculated.Results:Compliance (C) and Distensibility (D) were found lower in hypertension group thanthat in control group with significant difference (P<.05) over different parts of aorta.And Young s modulus (E) was found higher in hypertension group with significantdifference (P<.05). C decreased and D increased as the position of the aorta changedfrom ascending aorta to abdominal aorta (P<.05). E was found anomaly increase atabdominal aorta in Group B, while it decreased from ascending aorta to abdominalaorta in other groups.The maximum average velocity of the aorta happened at descending aorta. Peaksystolic blood flow velocity, forward flow decreased from ascending aorta toabdominal aorta, while regurgitant blood flow increased. The value of averagevelocity, peak systolic blood flow velocity were the highest in Group C. Regurgitantblood flow was more common during early diastolic phase in Group B (12/30,40.0%)than Group C (2/30,6.7%)(P<.05) at ascending aorta. At descending aorta, theincidence of regurgitation was the highest in Group B (29/30,96.7%)(P<.05), andregurgitation accrued during whole diastolic phase in30%patients. At abdominalaorta, the incidence of full-diastolic regurgitation was highest in Group B (15/30,50.0%).SBP and PP were found mild-moderate negative correlations with C and D over thewhole aorta, mild positive correlations with E over the whole aorta. DBP was found amild correlation with D and E at abdominal aorta.Conclusion:This study demonstrated that aortic elasticity decrease can reduce the blood flowvelocity in aorta. It is the reason of fluid pressure increase in the aortic lumen. Aorticregurgitation happens and prolongs in diastolic phase are very important reasons which lead to the rise of DBP. This may be interpreted with distal aortic (abdominalaorta) stiffness increase. Thus, aortic elasticity decrease is one of the generationmechanisms in primary hypertension. There must be obvious significance in maintainand restore the aortic elasticity for clinical treatment of hypertension.更多还原