Strain and SR appear useful and sensitive for evaluating myocardial function, especially for the subendocardial region.

For geometrically asymmetric LVs associated with ventricular aneurysms, RT3DE can accurately quantify LV volumes.

Objective Percutaneous valve replacements are presently being evaluated in clinical trials. As delivery of the valve is catheter based, the safety and efficacy of these procedures may be influenced by the imaging employed. To assist the operator and improve the success of the operation, we have performed transapical aortic valve replacements (AVR) using real-time MRI guidance (rtMRI). Methods 28 swine underwent rtMRI AVR on the beating heart. Stentless bioprostheses mounted on balloon-expandable stents was used. MR imaging (1.5T) was used to identify the critical anatomic landmarks. In addition to anatomic confirmation of adequate placement of the prosthesis, functional assessment of the valve and left ventricle and perfusion was also obtained with MRI. A series of acute feasibility experiments were conducted (n=18) in which the animals were sacrificed after valve placement and MRI assessment. Ten additional animals were allowed to survive and had follow-up MRI scans and confirmatory echocardiography at 1, 3, and 6 months postoperatively. Results rtMRI provided superior visualization of the landmarks needed. The time to implantation after apical access was 74±18 seconds. Perfusion scanning demonstrated adequate coronary flow and functional imaging documented preservation of ventricular contractility in all animals following successful deployment. Phase contrast imaging revealed minimal intra or para-valvular leaks. Longer term results demonstrated stability of the implants with preservation of myocardial perfusion and function over time. Conclusions rtMRI provides excellent visualization for intraoperative guidance of AVR on the beating heart. Additionally it allows assessment of tissue perfusion and organ function that are not obtainable by conventional imaging alone.

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For a variety of hemodynamic conditions, LVOT(Acc) was linearly related to the LV contractility index LV E(m) and was independent of loading conditions. These findings were consistent with numerical modeling. Thus, this Doppler index may serve as a good noninvasive index of LV contractility.

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The 3D digital color Doppler technique is a promising method for determining pulmonary regurgitant volumes and regurgitant fractions. It should have an important application in clinical settings.