Transcatheter Aortic Valve Replacement (TAVR) represents a significant advancement in treating heart valve disease, offering a less invasive alternative to traditional open-heart surgery for replacing a diseased aortic valve. It is an important option for those needing aortic valve intervention, implanting a new valve without requiring a large incision or opening the chest.
Understanding Aortic Stenosis and TAVR
Aortic stenosis is a common heart condition where the aortic valve, which controls blood flow from the heart to the rest of the body, narrows. This narrowing restricts blood flow, forcing the heart to work harder to pump blood through the smaller opening. Over time, this increased strain can lead to heart failure, with symptoms often including chest pain, shortness of breath, dizziness, and fatigue, especially with exertion.
TAVR replaces the stiffened or narrowed aortic valve with a new, artificial one. During the procedure, a new valve, typically made from animal tissue, is delivered to the heart through a catheter. Once positioned within the diseased valve, the new valve expands, pushing the old valve leaflets aside and regulating blood flow.
Primary Eligibility Requirements
Candidacy for TAVR primarily depends on a diagnosis of severe symptomatic aortic stenosis. Patients experience symptoms such as chest pain, shortness of breath, or fainting due to the condition. Objective measures, such as an echocardiogram, confirm severity, often showing a mean pressure gradient greater than 40 mmHg or a jet velocity exceeding 4.0 m/s across the valve, with an aortic valve area typically less than 0.8 cm².
Another central criterion is the patient’s surgical risk profile for traditional open-heart aortic valve replacement (SAVR). Initially, TAVR was approved for patients considered high-risk or inoperable for SAVR. Current guidelines have expanded eligibility to include patients at intermediate surgical risk, and increasingly, those at low surgical risk are also being considered.
Important Considerations for TAVR Candidacy
Beyond the primary criteria, other factors influence a patient’s suitability for TAVR. Anatomical considerations are crucial, particularly the suitability of blood vessels for catheter insertion. The transfemoral approach, using the artery in the groin, is preferred, but alternative access sites like the subclavian or carotid arteries may be used if peripheral vascular disease is present. The dimensions of the aortic annulus (the ring where the new valve will be seated) and the location of coronary arteries are also measured to ensure proper valve sizing and avoid complications.
Other medical conditions, known as comorbidities, impact TAVR candidacy and outcomes. Conditions such as chronic obstructive pulmonary disease, kidney disease, liver disease, and diabetes are assessed, as they can increase procedural risks or affect recovery. Frailty, a state of decreased physiological reserve common in older patients, is also evaluated, as it can predict poorer outcomes.
Certain contraindications can preclude a patient from TAVR. These include active infections, a life expectancy of less than one year due to non-cardiac causes, or a blood clot in the heart. Severe ventricular dysfunction or significant coronary artery disease that cannot be treated might also rule out TAVR.
The Multidisciplinary Evaluation Process
Eligibility for TAVR involves a comprehensive assessment by a specialized “Heart Team.” This multidisciplinary team typically includes interventional cardiologists, cardiac surgeons, imaging specialists, anesthesiologists, and geriatricians. Their collaborative approach ensures all aspects of a patient’s health are thoroughly reviewed.
Various diagnostic tests are performed to gather information for the team’s decision. An echocardiogram visualizes the heart’s structure and function, assessing aortic stenosis severity and heart function. Computed tomography (CT) scans provide detailed images of the aortic valve, the aorta, and surrounding blood vessels, which are crucial for procedural planning, valve sizing, and determining the safest catheter access route. Cardiac catheterization may also be performed to measure pressures within the heart and evaluate coronary arteries.