Transcatheter Aortic Valve Implantation: State of the Art

Aortic Valve 212 succumbed to his multiple comorbidities, his last transesophageal echocardiography demonstrated a functional aortic valve (Webb et al., 2009).A landmark success, this intervention was followed by a flurry of developments which resulted in considerable refinement of the procedure.This would culminate in increased safety, efficiency, and physician familiarity with the intervention.It is now estimated that over 15,000 patients worldwide have undergone a TAVI procedure (Geisbusch et al., 2010). Patient selectionWith any medical procedure, whether it is aortic valve replacement or medical treatment, the key to a favorable outcome is appropriate patient selection.By virtue of its recent development, access to TAVI remains restricted.Presently, TAVI is offered only to patients with symptomatic, critical aortic stenosis who have been deemed unsuitable for AVR.Evaluating a patient as inoperable depends on many factors, which include patient comorbidities, the surgeon's experience, and the institution in which the surgeon practices.Subtle details may influence a physician's judgment, which renders it difficult to provide a standard definition of a non-surgical candidate.With this limitation in mind, many institutions qualify patients with a logistic EuroScore calculated ≥ 20% or an STS (Society of Thoracic Surgery) predicted mortality risk score ≥ 10% as high-risk (Bande et al., 2010).Although not included in these two scoring systems, other criteria often cited when deeming a patient high-risk include: calcified porcelain aorta, chest wall deformities, cancer, cirrhosis with portal hypertension, neurological dysfunction, perceived frailty, severe chronic obstructive disease, previous cardiac surgery, severe cerebrovascular disease, low ejection fraction, and untreatable coronary artery disease (Saia et al., 2010).Traditionally, a bicuspid valve is considered a contraindication to TAVI.Due to its elliptical rather than circular shape, TAVI may result in a morphologically distorted valve and increased incidence of perivalvular leaks.Consequently, valve durability may be compromised.Recently published experience with 11 bicuspid TAVI demonstrated decreased gradients across the valve, and increased valve area.Two patients had moderate leaks.Although interesting, these results did not address the fundamental concern of TAVI in bicuspid valves related to their durability (Wijesinghe et al., 2010).Once patients are deemed inoperable, they must be carefully screened before proceeding to TAVI.In many centers, candidates are evaluated by a multidisciplinary committee consisting of cardiologists, cardiac surgeons, and cardiac anesthesiologists.Therefore, patients are evaluated on a case-by-case basis.Broad exclusion criteria may include dementia, life expectancy of less than 1 year, severely incapacitating neurological dysfunction, thoracic aneurysm, and a low likelihood of benefitting from the procedure (Shareghi et al., 2007).However, these selection parameters are subject to the discretion of each individual committee, and remain obscure.As TAVI becomes more prevalent, it will most certainly entail the development of specific guidelines to help orient physicians.A patient's anatomy is crucial in the selection process.The preoperative screening tests are similar in many centers.Transthoracic echocardiography and a coronary angiogram are standard.From a purely logistic point of view, a patient with and aortic annulus diameter < 18 mm or > 26 mm may be excluded due to limited availability of valve sizes (Webb et al., 2009).However, this exclusion is likely to be attenuated in the coming years as a wider range of valve sizes are developed.Computer tomography of the thorax, abdomen, and www.intechopen.com

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