15.4 Postoperative hemodynamic study of two bileaflet heart valves in aortic position

23rd World Congress of the ISCVS All reoperations were perfomed by median sternotomy with an oscillating electrical saw. Pre-sternotomy femorofemoral cardiopulmonary by-pass was utilized in 17 patients (15%). Results: Hospital mortality rates for primary procedures were 9% for MVR (without or with associated surgery), 4% for AVR and 9% for DVR. For operations, mortality rates were 7% for MVR, 8% for AVR and 6% for DVR. Cummulative follow-up was 230 patient-years in the MVR group, 210 in the AVR and DVR group with a maximum follow up of 36 months (mean 15 months, range 3-41 months). Actuarial survival, reoperation-free estimates and thromboembolic-free rates after reoperation were: AVR

MVR

1 year Actuarial survival Reoperation-free Thromboembolism

96.8 + 1.5 96.1 + 1.7 99.2 f 0.7

3 years 96.8 2 1.5 96.1 2 1.7 85.0 + 9.3

1 year 98.3 e 1.1 94.5 f 5.2 100 + 0

3 years 98.3 2 1.1 94.5 + 5.2 100 f 0

Conclusions: Our data support that the ATS bileaflet mechanical prosthesis is an excellent alternative for valvular reoperations after either conservative surgery or prosthetic valve replacement. It can be used safely in cases of documented prosthetic valve endocarditis without extensive annular destruction in either aortic or mitral positions.

15.4 Postoperative Hemodynamic Study of Two Bileaflet Heart Valves in Aortic Position

II? FLAMENG, A. VANDEPLAS, K. NARINE, II? DAENEN, l? HERIJGERS and M .-C. HERREGODS, Leuven, Belgium Background and aim of the study: In vivo hemodynamic assessment of bileaflet aortic valve prostheses using standardized echocardiography is still uncommon and therefore adequate comparison of valve types can rarely be made. We compared postoperative hemodynamics of St. Jude Standard valves (SJS) with those of Sorin Medical Bicarbon valves (BC) implanted in the aortic position, using pulsed, continuous and color Doppler echocardiography. Methods: The examination was performed 4 months after aortic valve prosthesis implantation in 76 patients (39 SJS valves and 37 BC valves). Valve sizes varied from 19 to 25 mm. Effective orifice area (EOA) was assessed using the continuity equation, mean and maximal instantaneous pressure gradients using the modified Bernouilli equation and prosthetic valve regurgitation was estimated by color Doppler flow imaging. Results: At valve sizes 21,23 and 25 mm, the SJS valves had a significantly lower EOA than the BC valves (I’ < 0.05). The BC valves, however, have a larger anatomical (AOA) and geometrical orifice area for given value-size than the SJS valves. Consequently, they were implanted in patients with a larger left ventricular outflow tract (P e 0.05). However, when EOA is related to the corresponding AOA, the BC valves still showed a larger EOA than the SJS valves (P c 0.05). Prosthetic valve regurgitation is low in both valve types. Conclusion: Valve size is not a good basis for comparison of hemodynamic profiles between valve types. Using the relationship between EOA and AOA, the hemodynamic profile of the

76

BC valve in the aortic position is shown to be superior to that of the SJS valve.

15.5 Prosthetic Patch can Cause Late Complications in Patients who Underwent Manouguian’s Annulus Enlargement and Aortic Valve Replacement

K. IMIANAKA, A. FURUSE, M . I~ZURE, Y; KOTSUKA, K. YAGYU and 0. TANAKA, Tokyo,

Japan We investigated the long term results of Manouguian’s annulus enlargement and found that late complications were not rare in patients to whom a prosthetic patch was applied. Among eight cases who underwent aortic valve replacement by Manouguian’s procedure since 1981, prosthetic material was applied to four cases (P group), and autologous pericardium was used in four cases (A group). (A) Mitral prolapse and regurgitation: One hundred percent in P group and 0% in A group. In three of four cases in P group, the grade of regurgitation was greater than moderate. In such cases, mobility of the annulus side of the anterior mitral leaflet was poor. The orifice side was well mobile and prolapsed. Regurgitant flow oriented toward the posterior wall of left atrium. Whereas in A group patients, the whole anterior leaflet moved well and smoothly. (B) Tear in mitral anterior leaflet: Twenty-five percent in P group and 0% in A group. The tear, which was noticed 9 years later, was around the tip of the prosthetic patch. The patient needed reoperation. (C) Supravalvular aortic stenosis: Twenty-five percent in P group and 0% in A group. This patient had undergone extensive aortoplasty when he was 6 years old and needed reoperation 7 years later. A prosthetic patch can cause late Conclusion: complications.

15.6 Initial Clinical Report of Results with the MedEng Mechanical Heart Valve

VI. SHUMAKOV, M .L. SEMENOVSKY, S.S. DOBROTIN and VK. NOVIKOV, Moscow, Russia In 1995 the Russian Ministry of Health approved the MedEng heart valve for clinical use based on its successful performance in accelerated fatigue tests, failure mode analysis, and biocompatibility studies. Over 1,500 MedEng valves have since been implanted. This first report of clinical results is from eight Russian cardiac surgical centers. The MedEng valve utilizes a new patented hydraulic design and is made of a proprietary anti-thrombo-genie isotropic pyrolytic carbon (IPC). Accelerated fatigue tests and failure mode analyses have shown that under stress this IPC behaves more like an elastic metal than other IPCs which are brittle and with stress behave like ceramics. SEM has shown minimal wear after the equivalence of over 20 years of use and that this IPC does not develop surface cracks, fissures or pits, the defects where platelet and fibrin emboli may form. The leaflets and annulus are made from solid blocks of IPC unlike other valves which only have a thin coating of PC over a substrate. The MedEng valve therefore does not develop the internal fault lines that

CARDIOVASCULAR SURGERY SEPTEMBER 1997