Transcatheter Aortic Valve Replacement (TAVR)

Transcatheter Aortic Valve Replacement (TAVR) represents a pivotal advancement in the percutaneous management of severe aortic valve stenosis. This angiographically-guided procedure is a viable therapeutic option, particularly for patients deemed at elevated surgical risk for conventional open-heart surgery. Notably, the indications for TAVR have expanded to include patients categorized as intermediate or low surgical risk.

UC Irvine's Advanced CT Protocol for TAVR 

The UC Irvine CT protocol for TAVR integrates a synergistic combination of ECG-gated cardiac CT angiography and whole-body CT angiography. This comprehensive approach enables a thorough evaluation of the aortic valve, aortic root and coronary arteries, and assessment of luminal dimensions. Furthermore, it provides critical insights into the tortuosity of the aorta and the iliac or subclavian arteries, which is essential for optimizing TAVR procedural access planning.

Our department utilizes state-of-the-art multislice CT scanners, distinguished by their 256 detectors, a rapid 0.27-second gantry rotation, and advanced ECG-gating capabilities. These technical specifications underpin the superior spatial and temporal resolution achieved, providing a highly reliable depiction of the aortic valve and root anatomy. This precision is fundamental for accurate prosthesis size selection, a critical determinant in preventing potential post-procedural complications such as prosthesis embolization or paravalvular regurgitation.

Post-Processing and Analysis of TAVR CT Data

Acquired TAVR CT protocol images undergo rigorous post-processing and analysis by our subspecialty fellowship-trained cardiothoracic radiologists. This process leverages FDA-approved, dedicated cardiovascular imaging software. CT data are reconstructed into high-resolution axial, coronal and sagittal images, and further processed into multiplanar and 3D reconstructions. A structured report, containing crucial measurements, is then generated to facilitate patient selection and procedural planning for the interventional cardiology and cardiothoracic surgery teams.

Within the TAVR cardiac CT protocol, UC Irvine cardiothoracic radiologists are meticulous in identifying the reconstructed cardiac phase exhibiting the largest annular dimensions, devoid of motion artifacts from multiphasic datasets. This ensures precise measurements and appropriate device sizing. This is accomplished through a retrospective ECG-gating scan with radiation dose modulation during the systolic phase of the cardiac cycle, thereby minimizing total radiation exposure. Furthermore, the imaging plane for measurements is scrupulously selected, acknowledging the dynamic changes in annular plane orientation throughout the cardiac cycle.

Radiologists precisely measure the aortic annulus luminal contour within the plane corresponding to the most basal attachment points of the three aortic valve leaflet cusps. Key measurements include annular area, diameters and perimeter, which are typically larger during the systolic phase. Systolic assessment of the aortic annulus is consistent with recent guideline recommendations aimed at mitigating inadvertent undersizing of the aortic valve prosthesis. Other critical findings and measurements encompass the heights of the coronary artery ostia, the aortic valve calcium score and the presence of calcifications within the left ventricular outflow tract (LVOT).