Multimodality Imaging and Structural Heart Interventions

SECTION 1 ECHOCARDIOGRAPHY IN STRUCTURAL HEART DISEASE

Recent advances in technology have led to the development of new devices and procedures that have greatly improved our ability to effectively treat structural heart abnormalities. Implementation of these procedures has been effective alternative treatment to surgery for several congenital and acquired diseases. The advent of transcatheter valve implantation techniques constitutes one of the main breakthroughs of the last decade. Such development and implementation are mostly related to continuous progress in cardiac imaging including echocardiography. Indeed, multimodality cardiac imaging has become essential for providing accurate patient selection, monitoring interventional procedures, and optimizing the success rate and minimizing complications. In this chapter, we present examples that demonstrate the critical importance of the use of echocardiography and multimodality imaging for the initial planning, intraoperative monitoring, and assessing of the results acutely and at follow-up of patients undergoing common structural heart and valve therapeutic interventions.

SECTION 2 PARAVALVULAR LEAKS

Prosthetic valves of any type are subject to unintended blood flow around the perimeter of the valve at the valve-tissue interface termed paravalvular leak. This is more common when the valve has been replaced a second time. Paravalvular leaks can be difficult to identify clinically. They are often difficult to auscultate and may manifest as unexplained heart failure or hemolysis.

For echocardiographic interrogation of an aortic prosthesis, views from the apex and parasternal views offer an evaluation of the left ventricular outflow tract (LVOT) and identification of regurgitant paravalvular jets. Echocardiographic assessment of mitral valve paravalvular leak is often more difficult due to acoustic shadowing from the prosthesis. Indirect measures such as pulmonary vein reversal and pulse and continuous Doppler interrogation of the annular areas can be helpful. Transesophageal echocardiogram (TEE) is often needed to view the prosthesis from the atrial perspective to make the diagnosis. In the clinical setting of a mitral prosthetic valve, and hemolysis or unexplained heart failure, TEE is recommended to further evaluate the valve characteristics and surrounding areas.

Current structural heart techniques allow for mitral and aortic paravalvular leaks to be treated with vascular occlusion devices. Once the leak is identified and localized, echocardiographic guidance in the cardiac catheterization laboratory is needed to confirm wire placement through the defect and successful placement of the closure device. Assessing relationships between prosthetic valve leaflets and devices is also aided by two- and three-dimensional echocardiography.¹

AORTIC PARAVALVULAR LEAKS

FIGURE 11.1 Aortic paravalvular leaks are easily identified by transthoracic echocardiography. The location can usually be identified by transthoracic echo; however, if this is not entirely clear, transesophageal echo can add more information. Fluoroscopic images can also localize the leak, but the combination of all of these modalities makes catheter and wire approaches much easier and quicker. The more information that is obtained in the planning stages, the easier and more efficient the procedure. Preprocedural preparation by the structural team and imaging team is important. Imaging allows for targets to be identified and quickly approached at the time of the procedure. Ao, aorta; LA, left atrium; LV, left ventricle.

FIGURE 11.2 This image defines the aortic paravalvular leak to be on the posterior aspect of the valve and anterior to the anterior mitral valve leaflet. Color Doppler shows this jet (yellow arrow).

FIGURE 11.3 Angiogram demonstrates the leak from this ascending aortic infection using a pigtail catheter. The regurgitant jet is to the left of the valve ring in this frontal projection (yellow arrow).

FIGURE 11.4 In another individual with a paravalvular leak, a small hourglass-shaped closure device (blue arrow) with its two end markers is seen across and closing a defect.

MITRAL PROSTHETIC VALVE PARAVALVULAR LEAK

FIGURE 11.5 Mitral paravalvular leaks are more occult than aortic paravalvular leaks. They hide behind the acoustic shadows of the prosthetic valve. They may manifest themselves as hemolysis or heart failure. Transesophageal views from the atrium allow the mitral valve to be viewed clearly and makes leaks around valve easily identified. From this view acoustic shadowing is avoided. Usually they are located close to the left atrial appendage; however, the second most common location is medially close to the interatrial septum and aorta. This latter location requires special effort to cross the septum and loop around back toward the aortic valve and interatrial septum to wire the lesion and place vascular plugs. The illustration here is one located in the typical location near the LAA.

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