Evaluation of mitral chordae tendineae length using four-dimensional computed

BACKGROUND Mitral valvuloplasty using artificial chordae tendineae represents an effective surgical approach for treating mitral regurgitation.Achieving precise measurements of artificial chordae tendineae length(CL)is an important factor in the procedure;however,no objective index currently exists to facilitate this measurement.Therefore,preoperative assessment of CL is critical for surgical planning and support.Four-dimensional x-ray micro-computed tomography(4D-CT)may be useful for accurate CL measurement considering that it allows for dynamic three-dimensional(3D)evaluation compared to that with transthoracic echocardiography,a conventional inspection method.AIM To investigate the behavior and length of mitral chordae tendineae during systole using 4D-CT.METHODS Eleven adults aged>70 years without mitral valve disease were evaluated.A 64-slice CT scanner was used to capture 20 phases in the cardiac cycle in electrocardiographic synchronization.The length of the primary chordae tendineae was measured from early systole to early diastole using the 3D image.The primary chordae tendineae originating from the anterior papillary muscle and attached to the A1-2 region and those from the posterior papillary muscle and attached to the A2-3 region were designated as cA and cP,respectively.The behavior and maximum lengths[cA(ma),cP(max)]were compared,and the correlation with body surface area(BSA)was evaluated.RESULTS In all cases,the mitral anterior leaflet chordae tendineae could be measured.In most cases,the cA and cP chordae tendineae could be measured visually.The mean cA(max)and cP(max)were 20.2 mm±1.95 mm and 23.5 mm±4.06 mm,respectively.cP(max)was significantly longer.The correlation coefficients(r)with BSA were 0.60 and 0.78 for cA(max)and cP(max),respectively.Both cA and cP exhibited constant variation in CL during systole,with a maximum 1.16-fold increase in cA and a 1.23-fold increase in cP from early to mid-systole.For cP,CL reached a plateau at 15%and remained elongated until end-systole,whereas for cA,after peaking at 15%,CL shortened slightly and then moved toward its peak again as end-systole approached.CONCLUSION The study suggests that 4D-CT is a valuable tool for accurate measurement of both the length and behavior of chordae tendineae within the anterior leaflet of the mitral valve.

Cerebrospinal fluid flow in empty sella syndrome and normal sellar regions measured by phase-contrast quantitative magnetic resonance

We used MRI to examine 38 healthy females and 38 female patients with empty sella syndrome. Cerebrospinal fluid flow was examined in six regions of interest, including the anterior clinoid processes, posterior clinoid processes, and 1.0 mm, 1.0 mm, 2.0 mm, --2.0 mm from the midpoint of the line between the anterior and posterior clinoid processes. The results revealed no significant differences in cerebrospinal fluid flow velocity and discharge in a single cardiac cycle, or indicators of cardiac cycles in the control group, indicating that the cerebrospinal fluid flow was relatively steady in the saddle area of the normal brain. In the empty sella syndrome group, cerebrospinal fluid hernia into the saddle area triggered a fluctuation of the anterior and posterior clinoid processes in the saddle area, while the flow in other regions in the saddle area was relatively steady this resulted in significant differences in cerebrospinal fluid flow velocity and discharge, as well as the cardiac cycle.

Effects of hypoxia on promoter of telomerase reverse transcriptase and cell cycle distribution in neonatal rat cardiac myocytes

On the hypothesis that telomerase reverse transcriptase (TERT) of cardiac myocytes (CMs) is consistent with cell cycle distribution as well as tumour cells, we plan to investigate the expression of TERT in CMs and how TERT is in keeping with CMs cycle distribution after birth and under hypoxia, and roughly understand how hypoxia affects activity of TERT promoter.

A novel angiography-based computational modelling for assessing the dynamic stress and quantitative fatigue fracture risk of the coronary stents immediately after implantation: Effects of stent materials, designs and target vessel motions

Fluctuating stress on the implanted coronary stents within cardiac cycle is an important mechanism of fatigue fracture,which is associated with in-stent restenosis and stent thrombosis.We developed a novel computational modelling to calculate the dynamic stress of stents based on the time sequence angiography immediately after treatment.Two groups of patient-specific cases(one same stent design treated in 4 different coronary arteries and one same artery actually/virtually implanted one stent with 3 different designs)were performed the dynamic stress analysis by this computational modelling and subsequently assessed the fatigue fracture risk by Goodman method.The motion of target arteries significantly impacts on distribution of the stress and the risk of stent fracture,particularly in the site of hinge motion.Both the location of stent stress concentration in the obtuse marginal artery and the“unsafe”region in the inverse fatigue safety factor contour co-registered with the position of complete transverse fracture 13 months later after implantation.Three stents with different designs had the same location of highest stress concentration at the hinge motion site of the actually/virtually treated artery.Higher strength stent materials are significantly lower the risk of stent fracture rather than stent designs.This new computational modelling might be a useful tool in assessment of fracture risk of the implanted stent and in optimizing new design of dedicated stent treated specific coronary arteries and mechanical properties in vivo of bioresorbable scaffold during degradation process.