Almost 300,000 prosthetic valves are implanted globally each year, and this number is anticipated to triple by the year 2050 due, in part, to the growing prevalence of valvular heart disease.1 Since the introduction of prosthetic heart valves in the 1950s, significant advances have been made in how they are implanted and evaluated in vivo. Advances in technology have led to the development of new materials for mechanical and biological valves that have dramatically improved the quality of life for patients with valve disease around the world. Additionally, the widespread adoption of catheter-based prosthetic valve delivery has fundamentally changed the responsibilities of the intraoperative echocardiographer. Despite these advances, prosthetic valves also have inherent limitations and risks associated with immediate or late postimplantation complications.
Similar to the evaluation of native cardiac valves (see Chapters 10, 11, and 12), transesophageal echocardiography (TEE) can provide detail regarding function and integrity of prosthetic valves using two-dimensional (2D), color flow Doppler (CFD), continuous-wave Doppler (CWD), pulsed-wave Doppler (PWD), and three-dimensional (3D) imaging modalities. However, the intraoperative environment presents significant challenges, including dynamic fluctuations in preload, myocardial contractility, and afterload. Furthermore, electrical pacing can frequently affect cardiac function. While echocardiographic evaluation of a newly implanted prosthetic valve is essential, the impact of prosthesis malfunction on adjacent valves and chambers must also be considered as part of a complete assessment. Despite these challenges, integration of information from the TEE examination provides a comprehensive assessment of the patient's overall cardiac status.
The following text provides an overview of (1) the indications for implantation of prosthetic heart valves, (2) the major types of prostheses, (3) their evaluation using TEE, (4) some inherent limitations of echocardiography, and (5) common prosthetic pathology.
INDICATIONS FOR PROSTHETIC VALVE PLACEMENT
A diseased valve that results in clinical symptoms will ultimately require intervention (repair or replacement) by percutaneous or surgical means. Malfunctioning valves may be native or previously repaired/replaced with a prosthesis. The indications for intervention are related to (1) severity of symptoms, (2) severity of valve malfunction, (3) ventricular response to changes in loading conditions, (4) impact on pulmonary and systemic circulation, and (5) impact on cardiac rhythm.2 Once intervention is considered necessary, the specific type of intervention is usually decided by a basic heart valve team of a cardiologist and cardiac surgeon or a multidisciplinary group, including an anesthesiologist, interventionalist, imaging specialist, and nursing staff. More complex decisions may be referred to a Heart Valve Center of Excellence.2
The most commonly replaced valves are those in the aortic and mitral positions, reflecting the prevalence of diseases that involve these valves. With significant improvements in mitral valve repair techniques, the frequency of repair has exceeded replacement for mitral regurgitation, and stenosis has become a more common indication for subsequent mitral valve replacement (Fig. 15-1).3,4 When the total number of ...