An abnormal aortic valve prosthesis typically has …
MRI - Prosthetic Heart Valves - MR-TIP: Database
Among ten animals allowed to survive, seven animals survived for 6 months. Three animals died between one and two weeks postoperative due to respiratory complications. The seven long term survivors were brought back for echocardiography and MRI scan 1, 3, and 6 months post procedure respectively. shows long term follow-up MRI scan for a pig at 1, 3, and 6 months, with regard to anatomic positioning, phase contrast and perfusion. In the follow-up studies, perfusion scanning demonstrated adequate coronary flow and functional imaging documented preservation of ventricular contractility. Phase contrast imaging revealed minimal intra or para-valvular leaks. The ventricular and valvular parameters of seven animals based on 1, 3, and 6 month follow-up echocardiography and MRI scan are presented in . ANOVA was performed to determine the significance of the differences between the 1, 3, and 6 month data. The p-values are also shown in . From these p-values we can conclude that there is no significant difference among the ventricular and valvular parameters during the 6 months post procedure. The degree of insufficiency of the aortic valve and the mitral valve over 6 months post procedure were measured and shown in . Longer term results demonstrated stability of the implants without migration or change in position and with preservation of myocardial perfusion and function over time. The histopathology reports of mid-term (6 month) verified that all the implanted aortic stent and valve assemblies were in place in the aortic root. The stents were properly seated in firm apposition to the aortic wall from the level of the prosthetic leaflets to the distal commissures tips. The prosthetic device leaflets remained cusp shaped and in the closed position exhibited good coaptation of the free edges. These necropsy findings correlated with both the MRI and echocardiography results. Two animals grew from 50kg to 200kg during the 6 month period of follow up; and the aortas partially outgrew the original implanted aortic stents. At necropsy after 6 months in these animals, some focal gaps were observed between the device and the native aortic wall in the area of the native aortic leaflet. These gaps allowed for perivalvular regurgitation which was noted on MRI and echocardiography prior to necropsy.
MRI Safety Guidance Prosthetic heart valves, ..
Retrospectively gated cine MRI revealed excellent myocardial function after valve implantation in both long- and short-axis views (snap shot is shown in , column1, row1 and row2). The phase-contrast CINE MR images (, column 1, row 3) show the through-plane blood velocity at both systole and diastole. These images confirm good systolic flow with excellent valve leaflet opening and no evidence of turbulence, diastolic regurgitant flow, or paravalvular leak. First-pass perfusion studies demonstrated adequacy of myocardial blood flow after valve placement in all animals following successful deployment. A first-pass perfusion scan at the base of the heart after valve implantation is shown in , column 1, row 4. These perfusion results confirm adequacy of blood flow at the tissue level, indicating proper valve positioning with respect to the coronary ostia. Echocardiographic results confirmed the MRI findings and further documented the stability of prostheses position and function over time. Necropsy of all these animals confirmed the deployed prosthetic valve location with respect to the aortic annulus and the mitral valve, and the commissures did not obstruct the coronary ostia. The observed distances between the commissural marker and a coronary ostia were 4mm or greater. These necropsy findings verified the MRI and echocardiography results.