HEMODYNAMIC COMPARISON BY DOPPLER-ECHOCARDIOGRAPHY OF VALVES IN THE AORTIC POSITION - VALUE OF THE CONTINUITY EQUATION TO ASSESS PROSTHETICDYSFUNCTION

In 281 patients, we used Doppler echocardiography to compare the hemod ynamic performance of different aortic prosthetic valves at three post operative stages and investigated the value of the continuity equation in diagnosing aortic prosthetic obstruction. A baseline study was per formed in 163 patients, a 5 +/- 2-month follow-up study was performed in 103 patients, and a 15 +/- 5-month follow-up study was performed in 65 patients. From baseline to the second study, left ventricular dias tolic diameter, heart rate, and maximum (MG) and mean Doppler-derived gradient (MeG)decreased significantly, and left ventricular shortening fraction, systolic blood pressure, stroke volume, and prosthetic valv ular area (PVA) increased significantly. No changes were found between the second and third studies. Thus, noninvasive hemodynamic values at the time of follow-up are reported in 171 patients: 86 with Bjork-Shi ley Monostrut, 27 with Carbomedics, 11 with Medtronic-Hall, 18 with Ha ncock modified and 29 with Toronto valve bioprosthesis. Patients impla nted with the Toronto had a larger prosthetic size (Monostrut 23 +/- 2 mm, Carbomedics 23 +/- 3 mm, Medtronic-Hall 23 +/- 2 mm, Hancock 23 /- 2 mm, Toronto 25 +/- 2 mm, P < 0. 01) despite a similar body surfac e area. MeG and MG were lower (MeG [in mmHg] Monostrut 12 +/- 5, Carbo medics 14 +/- 6 Medtronic-Hall 19 +/- 6 Hancock 11 +/- 4, Toronto 7 +/ - 5; P < 0.01 between Toronto and all others), and PVA was greater (Mo nostrut 2.0 +/- 0.7 cm(2), Carbomedics 1.8 +/- 0.8 cm(2), Medtronic-Ha ll 1.6 +/- 0.7 cm(2), Hancock 1.7 +/- 0.5 cm(2), Toronto 2.2 +/- 0.9 c m(2); P < 0.01 between Toronto and Carbomedics, Medtronic-Hall, and Ha ncock), even, compared with the same sizes in the other valves. A PVA of 0.9 cm(2) or less and MeG of 28 mmHg or more identified prosthetic obstruction with 100% sensitivity and 99% specificity. Hemodynamics ch ange significantly from the early to the late postoperative state. The Toronto valve stentless porcine bioprostheses performs hemodynamicall y better than other valves. PVA measurement using the continuity equat ion may accurately identify prosthetic obstruction.