Velocity Vector Imaging In Assessing The Cardiac Functional Evolution Of Hypertensive Rabbits Induced By Abdominal Aortic Coarctation

Backgroud:Hypertension is an important risk factor for many cardiovascular disease and cause heart failure.So it is very crucial to evaluate cardiac function in patients with hypertension. Routine echocardiography is unable to assess regional function. Recently developed velocity vector imaging(VVI) which based on speckle tracing technology is able to evaluate regional myocardial function accurately. Many reports have done several researches on myocardial function in special process of hypertension. But they can not clarify the dynamic change of cardic function in hypertension. So far there are few reports to assess heart function in hypertension by VVI.Objective:TO make hypertension model with New Zealand white rabbits; To assess regional myocardial function and global function of normal rabbits and rabbits with hypertension within 8 weeks; To investigate myocardial character in rabbits; To explore dynamic change of heart function in hypertention.Methods:Forty New Zealand white rabbits were divided into operation group(n=25) and control group(n=15) randomly. All rabbits were measured the diameter and velocity of abdominal aortic and blood pressure within pre-operation and pro-operation instantly,2 weeks,4 weeks and 8 weeks. And all rabbits were went with routine echocardiography pre-operation and pro-operation instantly,2 weeks,4weeks,6weeks.8weeks.And left ventricular long-axis view,short axis view at mitral valve level,papillary muscle level and apex level were collected and analysed by VVI.Results:Blood pressure increased instantly after operation,decreased a little in 2 weeks, and increased persistently in 4 weeks and 8 weeks.In operation group, the velocity of stenosis increased after operation and decreased after 4 weeks. The diameter of pro-stenosis increased while the velocity of pro-stenosis decreased gradually.Myocardial velocity decreased from base to apex and strain and strain rate had no change in long axis in normal rabbits. While velocity increased in anterior septum and anterior wall, strain and strain rate increased in anterior and lateral wall in short axis in normal rabbits.In operation group, Ss,SRs,SRd decreased gradually within 8 weeks.Vs Vd decreased a little in 2 weeks after operation and receded obviously within 4 weeks later.Conclusion:It's a good way to make hypertension model by coarctate abdominal aortic. VVI can be used to assess myocardium mechanism in rabbits with hypertension.Myocardia function has its own characteritics in both long axis and short axis in normal rabbits.Strain and strain rate decreased in 2 weeks operation,and are more sensitive than velocity. VVI is able to manifest myocardia damate in early stage and provide a reliabe quantitative tool to help diagnosing heart injury in hypertension.