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The Use of Peri-operative C-arm CT for the Accurate Placement of Percutaneous Aortic Valves
Author: Crowhurst J.; Aroney C. Walters DL.
Cardiology Department, Prince Charles Hospital, Brisbane, Australia
Introduction
Both 'Corevalve' and the 'Edwards' valve require the prosthesis to be accurately placed in the proximal ascending aorta.
Performing a Pre-operative or peri-operative CT scan can predetermine the correct C-arm angle for placement of the valve.
Purpose
Does Using Peri-operative C-Arm CT accurately determine the C-arm angle required for Aortic Valve implantation?
How does this compare to pre-operative CT?
Does this have any impact on procedural contrast and radiation usage?
Methods
Patients underwent either pre-operative CT scans (Siemens Somatom Definition) or peri-operative C-arm CT (Siemens syngo DynaCT Cardiac). Some had both and some neither.
Those that had Pre- or Post-operative CT had their CT predicted C-arm angulation decided using Siemens syngo InSpace 3D software.
The Angio lab C-arm (Siemens Artis zee) was positioned using the CT scan’s predicted angle. An aortogram was performed to confirm the accuracy.
We then noted the number of aortograms that were required to achieve an optimal profiling of the valve.
The total contrast media volume and radiation dose for the intervention and CT were recorded.
Fig 1. Preoperative CT of the aortic root
Fig. 2 Intraoperative syngo DynaCT
Fig. 3 Dual Source 64 Slice CT
Fig. 4 syngo DynaCT Cardiac
Fig. 5 A Trans-Apical Procedure
Fig. 6 Profiled Valve Deployment
Results
In the pre-operative CT group, the correct C-arm angulation was demonstrated in 4 of 14 cases.
In the peri-operative C-arm CT group the correct angulation was demonstrated in 14 of 15 cases (p=0.002).
Where both a pre and peri operative CT was performed, the two methods agreed in only 3 of 9 cases (33%).
The average re-valving procedural contrast volume for the pre-operative CT group was 285ml. The peri-operative group in comparison used a total of 210ml of contrast (p=0.002).
The Total Contrast Volume for the combined CT and re-valving procedure was 335 ml in the pre-procedure group and 210.94 ml in the peri-operative group.
The combined CT and re-valving procedure was 214.2 CGy and 255.5 CGy respectively.
Fig. 1 Type of Revalving Procedure
Fig. 2 Number of Cases for each Imaging Method
Fig. 3 Accuracy of CT Method in Predicting Optimal Valve Profile
Fig. 4 Number of Aortograms used to achieve Ideal Angle
Fig. 5 Contrast Usage
Fig. 6 Radiation Dose
Discussion
The translation of data from one modality to the next can be an issue with pre-operative CT. The patient may be rotated one way or another either on the CT table or the OR table.
Pre-operative CT has the benefit of evaluating anatomy and in the case of TAVI, the apex to the chest wall.
Contrast loading is of great importance, particularly in this patient cohort, most have some renal impairment. Our results indicate that the use of DYNA CT reduces the contrast volume used during the re-valving procedure.
Such is the positive effect of DYNA CT on the effective deployment of valve implants, all re-valving procedures have DYNA CT performed routinely at this centre.
Conclusions
For the accurate placement of percutaneous Aortic Valves, peri-operative C-arm CT (Dyna CT) demonstrates the correct C-arm angle more accurately, when compared to traditional pre-operative CT.
When Dyna CT is used, less contrast volume and radiation is delivered than if it is not used or if Traditional Pre-operative CT is used.
