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ATS Open pivot bileaflet prosthesis for aortic valve replacement

Barchetti Marco; Cerioli Giancarla; Cocconcelli Flavio; Asgharnejad Fahim Nasser; Golinelli Marco; Parravicini Roberto°

SALUS Clinic. Via U. Levi 7, Reggio Emila; ° University of Modena Medical School, Modena, Italy

Patients and Methods

We report our experience with the new bileaflet prosthesis ATS Medical (ATS Medical Inc., Minneapolis) in small aortic valve size , with respect to the AP series particularly studied for the small diameters (sizes n°18,20,22). We prospectively studied 93 consecutive patients who inplanted a small ATS aortic valve (n°<23 mm.), aged 45-80 years (mean 68 yrs). Transvalvular gradients were determined by transthoracic echocardiography. Patients were followed for 24 to 60 months. We had one (1.07%) hospital death non valve-related. There were no thrombo-embolic events, no valve-related compications and no deaths at follow-up. Echocardiographic data revealed excellent hemodynamic in all cases, with low transvalvular pressure gradients and absence of significant regurgitation. In particular, hemodynamic results were excellent in the AP series n° 18,20,22 with mean transvalvular gradients absolutly acceptable ranging from 21 mmHg in the n°18 size to 15 mmHg in the n°22. We conclude that ATS bileaflet valve has excellent hemodynamic characteristics, in particular the AP series, and good safety respect to late complications with a target therapeutic INR of 2.0 to 2.5.



The search for the ideal mechanical valve substitute has been continuing towards the goal of optimum haemodynamics, long-life durability and absence of trombogenicity.
Currently the bileaflet valve, especially the St. Jude Medical valves, is the most commonly implanted mechanical valve around the world (1,2). The ATS valve was developed by members of the original St. Jude team incorporating different design features: it is an open pivot, bileaflet, low profile pyrolitic carbon prosthesis, in wich the leaflet movement is controlled by spherical convex pivot guides, located on the inner circumference of the orifice ring. The leaflets open to an 85°angle providing near laminar flow (3). The aortic AP series of the ATS valve has been studied particularly for the small aortic valves and it has been designed for suprannular implantation.


Patients and Methods:

From september 1994 to september 1997 at the SALUS CLINIC (Reggio Emilia, Italy) 131 aortic mechanical ATS valves were implanted. The patients population were composed by 77 males and 54 females, aged between 45 to 80 years (average age 68 years).
In this paper we report the small size aortic group only. The most common ethiology was calcified degeneration ( 83 cases); we observed 8 bicuspid valves, 1 post-endocarditis, and 1 re-operation for thrombosis of mechanical valve. Stenosis of the native valve was 83% (77 pts), regurgitation 17% ( 16 pts). 22 patients required coronary artery bypass grafts, one had a triple coronary artery bypass plus endoaneurismorraphy (Cooley tecnique) for left ventricular aneurysm, 9 patients required a double valve replacement, one of these underwent also to a coronary artery bypass.
Pre-operatively 30 patients were in NYHA functional class II°, 51 patients in NYHA III°, 10 in NYHA IV° and 2 patients in NYHA V° (intubated and/or resuscitated).
All procedures were performed in standard cardiopulmonary bypass with mild hypotermia with anterograde crystalloid cardioplegia.
Aortic valve repalcement was performed with the valve implanted in the supra-annular position perpendicular in axis to the septum.
In coronary bypass patients distal vein grafts anastomosis were performed first, followed by valve replacement in the sequence of mitral, then aortic and lastly, if needed, left internal mammary artery anastomosis.
In the aortic position we implanted 14 valves n°18 (AP series), 4 n°19, 46 n° 20 (AP series), 2 n°21, and 33 n°22 (AP series).
Physical examinations, laboratory data and echocardiographic findings were performed at 6 days, 6 months and 1 year from operation time and then at the end of follow-up.
Echocardiographic data were obtained by transthoracic echocardiography considering transvalvular aortic systolic mean and maximum pressure gradients.
All patients check-out with anticoagulation therapy (warfarin) maintaining an INR range of 2.0-2.5 in synus rythm and 2.5-3.0 in atrial fibrillation (4).



There were no operative and in-hospital deaths.
During hospitalization we did not observed valve-related complications.
The follow up for complications has been conducted from 18 to 36 months. The definition of complications was in accordance with published guidelines for reporting valve-related morbidity and mortality (5).
We did not observed any late death or complication. NYHA functional class improved in all except 2 patients in wich did not change; no patients showed a worst functional class.
All patients, except two, maintained an INR range of 2.0-2.5. There have been no thrombo-embolic event.
Lactate-dehydrogenase showed normal values in every determination time.
Echocardiographic data revealed excellent haemodynamics with low transvalvular gradients and absence of significant regurgitation ; in particular, the AP series valves (size n° 18, 20, 22) showed very good mean gradients (Table 1).

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In our series of 93 patients with aortic ATS Medical aortic valves AP series there have been no valve-related thrombosis or bleeding events under coagulation therapy at INR range of 2.0-2.5 and no valve-realted deaths.
The ATS valve has dimonstrated good results in the aortic position at follow up in our as in others experiences (3,4).
The transvalvular echocardiographic gradients appear to compare favorably to the data of other bileaflet valves in the smaller aortic sizes (7,8).



1. Arom KV, Nicoloff DM, Kersten TE, Northrup WF, Lindsay WG, Emery RW Ten years experience with St. Jude Medical prosthesis.
ANN THORAC SURG, 1989;47:831-37
2. Kratz JM, Crawford FA, Sade RM, Crumbley AJ, Strond MR St. Jude prosthesis for aortic and mitral valve replacement: a ten-years experience
ANN THORAC SURG, 1993;56:462-68
3.  Westaby S, Van Nooten G, Sharif H, Pillai R, Cases F Valve replacement with the ATS open pivot bileaflet prosthesis
4. Parravicini R, Barchetti M, Reggianini L, Cocconcelli F, Asgharnejad Fahim N, Cerioli G, Amorth E, Zobbi G, Belloni G.P, Tonelli M ATS prosthetic valves AP series: echocardiographic evaluation
In "Advancing the tecnology of bileaflet mechanical heart valves" A. Krian, J:M: Matloff, D:M: Nicoloff, editors Springer, 1998
5. Nicoloff DM, Friedberg HD, Villafana MA ATS Medical Open Pivot Valve with low intensity anticoagulant therapy CARDIOVASCULAR SURGERY, 1996;Suppl.1,4:152-3
6. Edmunds LH, Clark RE, Cohn LH, Miller DC, Weisel RD Guidelines for reporting morbidity and mortality after cardiac valvular operations ANN THORAC SURG, 1998;46:257-9
7. Nanda NC, Cooper JW, Mahan EF, Fan PH Echocardiographic assessment of prosthetic valves CIRCULATION, 1991; 84 (Suppl.2):228-39
8. Reisner SA, Meltzer RS Normal values of prosthetic valve doppler echocardiographic parameters: a review
J AM SOC ECHOCARDIO, 1988;1:201-10

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