Evaluation of 17-mm St. Jude Medical Regent prosthetic aortic heart valves by rest and dobutamine stress echocardiography
BACKGROUND
The 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 RESULTS
The 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 microg/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 +/- 5.8 mmHg, respectively; EOA and EOAi resulted 1.14 +/- 0.3 cm(2) and 0.76 +/- 0.2 cm(2)/m(2); DVI was normal (0.50 +/- 0.1). At follow-up LVM and LVMi decreased significantly from pre-operative value of 258 +/- 43 g and 157.4 +/- 27.7 g/m(2) to 191 +/- 23.8 g and 114.5 +/- 10.6 g/m(2), respectively. DSE increased significantly HR, CO, EF, MxGP (up to 83.4 +/- 2 1.9 mmHg), MnPG (up to 43.2 +/- 12.7 mmHg). EOA, EOAi, DVI increased insignificantly (from baseline up to 1.2 +/- 0.4 cm(2), 0.75 +/- 0.3 cm(2)/m(2) and 0.48 +/- 0.1 respectively). Two patients developed significant intraventricular gradients.


CONCLUSION
These 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.