Abstract
BackgroundThe prosthesis used for aortic valve replacement in patients with small aortic root can be too small in relation to body size, thus showing high transvalvular gradients at rest and/or under stress conditions. This study was carried out to evaluate rest and Dobutamine stress echocardiography (DSE) hemodynamic response of 17-mm St. Jude Medical Regent (SJMR-17 mm) in relatively aged patients at mean 24 months follow-up.Methods and resultsThe study population consisted of 19 patients (2 men, 17 women, mean age 69.2 ± 7.3 years). All patients underwent rest Doppler echocardiography before and after surgery and basal and DSE at follow up (infused at rate of 5 micrg/Kg/min and increased by 5 microg/Kg/min at 5 min intervals up to 40 microg/Kg/min). The following parameters were evaluated at rest and/or under DSE: heart rate (HR), ejection fraction (EF), cardiac output (CO), peak and mean velocity and pressure gradients (MxV, MnV, MxPG, MnPG), effective orifice area (EOA), indexed EOA (EOAi), left ventricular mass (LVM), indexed LVM (LVMi), Velocity Time Integral at left ventricular outflow tract (VTI LVOT) and transvalvular (Aortic VTI), Doppler velocity index (DVI). At rest MxPG and MnPG were 29.2 ± 7.1 and 16.6 ± 5.8mmHg, respectively; EOA and EOAi resulted 1.14 ± 0.3 cm2 and 0.76 ± 0.2 cm2/m2; DVI was normal (0.50 ± 0.1). At follow-up LVM and LVMi decreased significantly from pre-operative value of 258 ± 43g and 157.4 ± 27.7g/m2 to 191 ± 23.8g and 114.5 ± 10.6g/m2, respectively. DSE increased significantly HR, CO, EF, MxGP (up to 83.4 ± 2 1.9mmHg), MnPG (up to 43.2 ± 12.7mmHg). EOA, EOAi, DVI increased insignificantly (from baseline up to 1.2 ± 0.4 cm2, 0.75 ± 0.3cm2/m2 and 0.48 ± 0.1 respectively). Two patients developed significant intraventricular gradients.ConclusionThese data show that SJMR 17-mm prostheses can be safely implanted in aortic position in relatively aged patients, offering a satisfactory hemodynamic performance at rest and under DSE, with full utilization of its available orifice, suggesting that a possible mild prosthesis-patient mismatch is not an issue of clinical relevance when this small prosthesis is used. Rest and Dobutamine stress echocardiography is a useful and effective means for evaluating prosthesis hemodynamics and for monitoring the expected LVH regression.
Highlights
The prosthesis used for aortic valve replacement in patients with small aortic root can be too small in relation to body size, showing high transvalvular gradients at rest and/or under stress conditions
left ventricular mass (LVM) and left ventricular mass index (LVMi) decreased from pre-operative values of 258 ± 43g and 157.4 ± 27.7g/ m2 to 191 ± 23.8g and 114.5 ± 10.6 g/m2, respectively (p < 0.00001 and
heart rate (HR) increased from a baseline of 64.5 ± 10 to 100.6 ± 28 beats/min (p < 0.001); cardiac output (CO) increased from a baseline of 4.7 ± 1.6 L/min to 8.2 ± 2 L/min (p < 0.0001); ejection fraction (EF) increased from a baseline of 58.4 ± 8% to 68 ± 9.9% (p < 0.008)
Summary
The prosthesis used for aortic valve replacement in patients with small aortic root can be too small in relation to body size, showing high transvalvular gradients at rest and/or under stress conditions. This study was carried out to evaluate rest and Dobutamine stress echocardiography (DSE) hemodynamic response of 17-mm St. Jude Medical Regent (SJMR-17 mm) in relatively aged patients at mean 24 months follow-up. Patients who receive a small aortic valve prosthesis may remain asymptomatic following surgery and Doppler echocardiography may show normal or mild elevated transvalvular gradients at rest, even in patients with large body surface area (BSA) [1,2,3,4,5]. This may not be representative of a patient's daily activities. The SJMR-17 mm valve, having a large actual (nominal) orifice area (AOA) as provided by manufacturer equivalent to a standard valve one size larger, seemed appropriate to be implanted and evaluated in relatively aged patients with aortic valve stenosis and small aortic root, where other alternatives, such as annulus enlargement, in order to make space for a larger valve prosthesis were not suitable because of the increased operative risk
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