Diagnostic Methods Valvular Heart Disease

For patients with stenotic native valves, the modified Bernoulli equation (AIP = 4v2) may be applied to Doppler-measured transvalvular velocities to yield an accurate estimate of transvalvular gradients. Although it would be useful if the same approach could be used for those with stenotic prosthetic valves, no previous study has validated the Doppler technique in this setting. We therefore recorded simultaneous continuous-wave Doppler flow profiles and transvalvular manometric gradients in 12 catheterized patients in whom all atrial and ventricular pressures were directly measured (transseptal left atrial catheterization and transthoracic ventricular puncture were performed where necessary). A total of 13 prostheses were studied: 11 mitral (seven porcine, three Starr-Edwards, and one Bjiork-Shiley) and two tricuspid (one porcine and one Bjork-Shiley). The Doppler-determined mean gradient was calculated as the mean of the instantaneous gradients (AP = 4v2) at 10 msec intervals throughout diastole. The correlation of simultaneous Doppler (DMG) and manometric mean gradients (MG) for the whole group (n 13) demonstrated a highly significant relationship (MG = 1.07DMG + 0.28; r = .96, p = .0001). The correlation was equally good for porcine valves alone (n = 8) (MG 0.O6DMG + 0.55; r = .96, p = .001) and for mechanical valves alone (n = 5) (MG = 1.06DMG -0.04; r = .93, p = .02). In a subset of patients without regurgitation (n = 8), prosthetic valve areas were estimated by two Doppler methods originally described by Holen and Hatle, as well as by the invasive Gorlin method. As expected from theoretical considerations, a close correlation was not demonstrated between results of the Gorlin method and those of either Hatle's Doppler method (r = .65, fp = NS) or Holen's method (r = .14, p NS). Comparison of the results of the two Doppler methods yielded a somewhat closer correlation (r = .73, p .05). These results suggest that in patients with disk-occluder, ball-occluder, and porcine prosthetic valves, Doppler estimates of transvalvular gradients are virtually identical to those obtained invasively. Circulation 74, No. 4, 786-795, 1986. IN 1960, Starr and Edward1 and Harken et al.' implanted the first intracardiac prosthetic valves in humans, and introduced a new era in cardiology. Unfortunately, subsequent experience has demonstrated that prosthetic valves may become regurgitant or pathologically stenotic for a variety of reasons.' Detection of such From the Cardiac Unit, Massachusetts General Hospital, Boston. Address for correspondence: Gerard T. Wilkins, M.B., Ch.B., Massachusetts General Hospital, Cardiac Non-Invasive Laboratory, Boston, MA 02114. Received Jan. 30, 1986; revision accepted July 3, 1986. Dr. Wilkins is supported by the Royal Australasian College of Physicians as the Odlin Cardiovascular Research Fellow, and formerly by the National Heart Foundation of New Zealand as the Ivan and Maude St. Romain Research Fellow. Dr. Levine is a Medical Foundation Research Fellow of the Medical Foundation, Inc., Boston. abnormalities may pose a diagnostic challenge because the symptoms of valvular dysfunction are frequently nonspecific and the signs are difficult to detect on routine clinical examination. The identification of prosthetic valve stenosis is particularly problematic. Although noninvasive diagnostic testing in the form of phonocardiography, fluoroscopy, and M mode and cross-sectional echocardiography4-7 has been applied with limited success, to date the mainstay of investigation for prosthetic valve stenosis has been cardiac catheterization with careful manometric measurements of gradients and cardiac output. This form of investigation, however, is complicated by the risks associated with crossing prosthetCIRCULATION by gest on M ay 9, 2017 http://ciajournals.org/ D ow nladed from DIAGNOSTIC METHODS-VALVULAR HEART DISEASE ic valves, and patients often require direct cardiac chamber puncture (transthoracic or transseptal). In the presence of multiple prosthetic valves, the problem is compounded. A noninvasive method capable of reliably assessing prosthetic valve function would therefore be invaluable. In recent years, studies have shown that Doppler echocardiography is capable of measuring the flow velocity across native valves. These velocites may be used to calculate transvalvular pressure gradients by the modified form of the Bernoulli equation (AP = 4v2).t"l In theory, this general Doppler approach should also be applicable to prosthetic valves. The situation is complicated, however, since flow patterns across prosthetic valves are fundamentally different from those found normally, with further variation between types and subtypes of prostheses. Studies of porcine valves in vitro suggest that their flow stream is central and similar to that through human aortic valves.12 13 Flow beyond mechanical valves, however, is considerably different, with semicentral flow demonstrated in tilting-disk valves and peripheral flow in ball valves.12-14 Holen et al.15' 116 have demonstrated an excellent correlation between the Doppler-estimated mean gradient and the simultaneously recorded manometric mean gradient across the mitral valve in nine patients with Bjdrk-Shiley and in eight patients with Hancock valves. These patients were studied soon after valve replacement and presumably had normally functioning prostheses. More recent data, however, suggest that the correlation between Dopplerand catheter-determined gradients may, in fact, be less good.'7 Thus, limited and conflicting data are available concerning the accuracy of the Doppler measurements of transvalvular gradients in patients with prostheses in the mitral or tricuspid position, and virtually nothing is known about the accuracy of these measurements in the group in which they are most important (i.e., those with prosthetic dysfunction). In this study, therefore, we examined a group of patients with clinical evidence of prosthetic valve dysfunction to determine whether the mean valve gradients measured by continuous-wave Doppler echocardiography in disk-occluder, ball-occluder, and porcine heterograft prostheses, in either the mitral or tricuspid position, correlate with those simultaneously measured manometrically. In addition, because hemodynamic and Doppler data have both been previously used to calculate valve orifice areas in native and prosthetic valves, we also compared these derived variables with one another for our patient