Abstract
Aortic valve annular complex was rediscovered after the introduction of transcatheter aortic valve replacement; and imaging has been crucial in determining the annular geometry. Although the procedure has evolved, complications related to the annular mechanical response following valve implantation, such as aortic insufficiency, still occur in practice. We documented the feasibility of invasive assessment of aortic valve annular complex and the detection of induced aortic insufficiency via intravascular ultrasound with ChromaFlo® technology in a porcine model.
Aortic annulus measurement is a crucial step in prosthesis size selection for transcatheter aortic valve replacement (TAVR). Optimizing valve size may reduce the incidence of serious complications, such as valve embolization, annular rupture, atrioventricular conductance disturbances, and residual aortic regurgitation (AR) . Although multimodality imaging has become an integral part of the procedure to determine valve size and strategy , the above complications still occur in daily practice, in part because of the currently unpredictable mechanical response of aortic annular complex following valve deployment .
Trans-esophageal echocardiography (TEE) is considered the intra-procedural gold standard imaging for TAVR due to its ability to detect a wide range of associated potential complications . However, it is usually performed under general anesthesia, it can obstruct the optimal fluoroscopic view during the valve positioning and, although rarely, it may lead to other hazards during probe insertion. Additionally, the AR quantification through Doppler techniques after TAVR remains problematic as multiple eccentric jets often occur and portions of the prosthesis may not be adequately visualized due to acoustic shadowing . Furthermore, TEE tends to categorize AR severity higher than transthoracic echocardiogram . Thus, there is an unmet clinical need for a refinement of procedural imaging, especially with respect to accurate determination of AR severity, since the treatment options for reduction of AR are limited and not without risk .
The use of aortic valve ultrasound (AVUS) was recently described in intra-procedural assessment of TAVR . While AVUS with an 8.2 F catheter (Visions PV, Volcano Corporation, San Diego, CA) appears promising for accurate aortic valve complex measurements, it lacks the ability to evaluate for blood flow and to locate and quantify AR. An alternative technology that may overcome these limitations is AVUS with ChromaFlo® (Volcano Corporation, Rancho Cordova, CA), which provides a color-enhanced display of red blood cells and enables invasive imaging of blood flow superior to Doppler estimates.
Herein, we demonstrate the feasibility of ChromaFlo® aortic valve complex imaging in a porcine model of AR. The experiment consisted of leaflet perforation ( Figs. 1 and 2 ) and ChromaFlo® imaging acquisition through the perforation from the supra and infra annular perspectives ( Fig. 3 ) and from the center of the native aortic valve ( Fig. 4 ). Anatomical correlations of the aortic valve complex and the induced perforation are demonstrated in Fig. 5 . Our main findings are that the appraisal of the dynamic effective annular aortic area and AR is feasible using ChromaFlo® without the disadvantage of additional contrast or radiation exposure.
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