Round Valve in an Oval Hole
Right-Sizing Prosthetic Aortic Valves With Preoperative Computed Tomography
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- aortic valve
- aortic valve stenosis
- computed tomography
- transcatheter aortic valve replacement
Progressive narrowing of the aortic valve orifice eventually leads to limitations in cardiac output and myocardial blood flow, particularly during exercise or other physiological stress. The pressure gradient across the stenotic aortic valve is a useful and reproducible measure of the severity of the stenosis in most patients. The mainstay of therapy for aortic stenosis is relief of the fixed obstruction that has traditionally been accomplished with surgical aortic valve replacement (SAVR). However, during the past decade, transcatheter aortic valve replacement (TAVR) has rapidly evolved as an alternative therapy. Despite improvements in valve design and delivery, all prostheses are hemodynamically inferior to healthy native valves and, therefore, valve replacement results in the exchange of de novo valve disease for prosthetic valve disease. Because the gradient across most prosthetic valves is directly related to their size, a paradigm of aortic valve surgery is to implant the largest valve possible to minimize the transvalvular pressure gradient and maximize the ability to generate increased cardiac output in times of increased demand.
See Article by George et al
The potential placement of a prosthetic valve that is relatively too small for a patient is a significant concern (Figure A and B). This condition, which has been referred to as patient–prosthesis mismatch (PPM), results in persistent imbalance between the hemodynamic abilities of the aortic prosthesis and the required cardiac output of the patient. Resting cardiac output and transvalvular flow increase proportionally with body surface area; therefore, the recommended parameter for diagnosis of PPM is the indexed effective orifice area (effective orifice area divided by body surface area). Traditionally, the presence of PPM is defined as an indexed effective orifice area of <0.85 cm2/m2 and severe PPM is <0.65 cm2/m2.1 PPM is the most common cause of elevated …