title: Hemodynamics of 21 and 23 mm Medtronic Hall valves by Doppler echocardiography.
abstract: To evaluate the in vivo hemodynamics of smaller-sized (21 mm and 23 mm) Medtronic Hall (MH) valves in the aortic position, we measured the maximal pressure gradients (maxPG) at rest and during dobutamine (DOB) administration by continuous-wave Doppler echocardiography in 20 patients with aortic valve replacement. Their body surface areas (BSA) averaged 1.54 m2 in MH21 (n = 10) and 1.57 m2 in MH23 (n = 10). For comparison, the same study was performed in 18 patients who underwent replacement with 21 mm and 23 mm Björk-Shiley (BS) convexo-concave valves [BSA averaged 1.52 m2 in BS21 (n = 9) and 1.58 m2 in BS23 (n = 9)] and in 10 patients with 19 mm St. Jude Medical (SJM) valves (BSA averaged 1.43 m2). The maxPG was calculated as 4 Vmax2 (V = peak velocity) by means of a simplified Bernoulli equation. Cardiac output (CO) was obtained from a simultaneously recorded M-mode echocardiogram by Gibson's formula. A significant correlation, revealed as a second-degree polynomial regression equation, was found between CO and maxPG at rest and during DOB administration in each type or size of prosthesis.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Surgery, Kobe University School of Medicine, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ota
authors.forename: K
authors.initials: K
authors.lastname: Iwahashi
authors.forename: M
authors.initials: M
authors.lastname: Okada
authors.forename: K
authors.initials: K
authors.lastname: Nakamura
mesh_terms: D000704:Analysis of Variance; D001021:Aortic Valve; D004280:Dobutamine; D004452:Echocardiography / Q000706:statistics & numerical data; D015150:Echocardiography, Doppler / Q000706:statistics & numerical data; D005069:Evaluation Studies as Topic; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis / Q000706:statistics & numerical data; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D011474:Prosthesis Design; D012146:Rest / Q000502:physiology; D013997:Time Factors
chemical_list: D004280:Dobutamine