Noninvasive in vivo and in vitro study of the St. Jude mitral valve prosthesis: Evaluation using two dimensional and M mode echocardiography, phonocardiography and cinefluoroscopy

Abstract

Fifteen patients with clinically normal function of a St. Jude mitral valve prosthesis were studied with two dimensional and M mode echocardiography, Cinefluoroscopy and phonocardiography 8 to 292 days after valve replacement. The valve was readily imaged from the left sternal edge and cardiac apex in all patients. On two dimensional echocardiography from the long axis and four chamber views, minimal end-diastolic and endsystolic distances between the interventricular septum and prosthetic valve were 18 ± 5 mm and 13 ± 3 mm, respectively (mean ± standard deviation). On M mode echocardiography both leaflets were imaged throughout the cardiac cycle from the left sternal edge and their motion relative to the valve ring and to one another was easily evaluated. The apical transducer position permits quantitative assessment of individual leaflet motion. Maximal individual diastolic leaflet excursion was 8.7 ± 1 mm and the velocity of leaflet opening and closure was 364 ±103 and 678 ±115 mm/s, respectively. Asynchronous early closure of the posterior leaflet was observed during long cardiac cycles in six of seven patients with atrial fibrillation; the seventh patient had a rapid ventricular response and no long cardiac cycles. Diastolic fluttering of one or both leaflets was also seen during atrial fibrillation after rotation of the patient from the supine to the left lateral decubitus position. Three of the six patients with asynchronous leaflet closure underwent Cinefluoroscopy, and similar leaflet behavior was documented in all. An atrial systolic wave was inscribed in the valve echogram in six of eight patients with sinus rhythm. Phonocardiography recorded prosthetic valve opening and closing sounds occurring 60 ± 20 ms after aortic closure and 61 ± 12 ms after the QRS complex, respectively. The prosthetic valve opening and closure sound amplitude ratio was 0.11 ± 0.06. A clear plexiglass water bath phantom was fitted to a pulse duplicator and constructed so as to permit in vitro simulation of valve echograms under a variety of conditions. With this method, it was possible to reproduce or approximate all images obtained in patients from both echocardiographic transducer positions.