MItral Stenosis: Pressure Half-Time

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Circulation. 1979 Nov;60(5):1096-104.

Noninvasive assessment of atrioventricular pressure half-time by Doppler ultrasound.

Hatle L, Angelsen B, Tromsdal A.

The mean pressure drop across the mitral valve and atrioventricular pressure half-time were measured noninvasively by Doppler ultrasound in 40 normal subjects, in 17 patients with mitral regurgitation, 32 patients with mitral stenosis and 12 with combined stenosis and regurgitation. In normal subjects pressure half-times were 20--60 msec, in patients with isolated mitral regurgitation 35--80 msec and in patients with mitral stenosis 90--383 msec. There was no significant change in pressure half-time with exercise or on repeat examinations, indicating relative independence of mitral flow. In 25 patients with mitral stenosis and seven with combined stenosis and regurgitation, pressure half-time was related to mitral valve area calculated from catheterization data. Increasing pressure half-times occurred with decreasing mitral valve area, and this relationship was not influenced by additional mitral regurgitation. Noninvasive measurement of pressure half-time together with mean pressure drop was useful for evaluating patients with mitral valve disease.

Acta Med Scand. 1982;211(6):433-6.

Doppler ultrasound in mitral stenosis. Assessment of pressure gradient and atrioventricular pressure half-time.

Knutsen KM, Bae EA, Sivertssen E, Grendahl H.

In 16 patients with mitral stenosis (MS), alone or in combination with either mitral insufficiency (2 pats.) or aortic valve disease (3 pats.), the mean diastolic pressure gradients across the mitral valve calculated by Doppler ultrasound were significantly correlated to the catheterization data. The average mean pressure drop by Doppler was 11.8 mmHg and by catheterization at rest 16.7 mmHg. A significant correlation between gradients was also found in 5 patients who exercised supine on a bicycle. Atrioventricular pressure half-time (T1/2), i.e. the time during which the pressure drops from the peak value to half of its initial value by the Doppler technique, was significantly correlated to mitral valve area (MVA) determined from catheterization data. Increasing T1/2 reflected decreasing MVA. It is concluded that Doppler ultrasound is a useful method in the evaluation of patients with MS.

J Am Coll Cardiol. 1983 Oct;2(4):707-18.

Quantification of pressure gradients across stenotic valves by Doppler ultrasound.

Stamm RB, Martin RP.

Two-dimensional echocardiography has proven very useful in assessing valvular heart disease, but the technique is limited in certain groups of patients and is unable to quantify a transvalvular pressure gradient. Advances in the Doppler ultrasound techniques have made it possible to noninvasively measure velocity of flow across a stenotic heart valve and to calculate the pressure gradient. A commercially available, continuous and pulse wave Doppler instrument was utilized to assess the transvalvular pressure gradient in patients with mitral and aortic stenosis and the transmitral pressure half-time to calculate mitra valve area. Thirty-five consecutive adult patients with suspected aortic stenosis and 30 adult patients with suspected mitral stenosis underwent Doppler ultrasound examination within 24 hours of cardiac catheterization. An adequate Doppler examination was obtained in 81% of the patients with aortic stenosis, with a correlation between the Doppler-derived transaortic gradient and the catheterization-derived gradient of 0.94. The Doppler-measured gradient accurately separated those patients with significant aortic stenosis (gradients of greater than 50 mm Hg) from those patients with noncritical aortic stenosis. Similarly, an adequate Doppler examination was obtained in 90% of the adult patients with mitral stenosis. There was also close correlation between the mitral valve area and mean pressure gradient measured by the Doppler technique and that obtained at the time of cardiac catheterization (r = 0.87 and 0.85, respectively). The Doppler technique proved to be useful in those patients who had also undergone prior mitral commissurotomy. This study confirms that the combined continuous pulse wave Doppler technique will serve as a valuable addition to the diagnostic capabilities offered by echocardiography.

J Cardiogr. 1984 Jun;14(1):149-61.

Non-invasive estimation of transmitral pressure gradient and mitral valve area in mitral stenosis by an ultrasonic pulsed Doppler technique.

Asao M, Kitabatake A, Inoue M, Tanouchi J, Morita T, Masuyama T, Mishima M, Shimazu T, Ishihara K, Fujii K, et al.

We attempted to estimate transmitral pressure gradient and mitral valve area (MVA) noninvasively in mitral stenosis (MS) by a bi-directional pulsed Doppler flowmeter combined with an electronic two-dimensional echocardiograph. Eleven patients with MS in sinus rhythm were studied by cardiac catheterization. Fifteen healthy subjects (H) served as normal control. The pulsed Doppler flowmeter operated with a carrier frequency of 2.5 MHz, a pulse repetition rate of either 5 KHz or 10 KHz and a sample volume of 1 X 3 X 3 mm. The velocity of transmitral central flow was measured by this system, monitoring audible Doppler sounds and cardiac images which depict the anatomic location of the sampling site. The Doppler signal was analyzed by a sound spectrograph. In estimating the transmitral pressure gradient and MVA, we employed a Doppler parameter (half time) defined as the time for instantaneous maximal blood flow velocity to reduce to one-half from its rapid inflow peak, which is independent of the angle between the ultrasonic beam and blood flow. Transmitral pressure gradient (delta P100) was measured as the pressure gradient between either left atrial or pulmonary capillary pressure and left ventricular pressure at the point after 100 msec from the nadir of left ventricular early diastolic pressure [( LA or PC--LVDP]100). MVA was obtained using a Gorlin's formula. The transmitral blood flow velocity in both MS and healthy groups revealed a narrow frequency band pattern with two peaks, R and A, in diastole. The former peak occurred during rapid inflow phase and the latter following atrial contraction. In the healthy group, the descent rate of R wave was increased than that in the MS group. The square root of the pressure gradient also reduced linearly with transmitral flow velocity in the MS group. Thus in the MS group, the transmitral velocity was directly proportional to the square root of the pressure gradient as described by a Bernoulli theorem, and the half time was proportional to the transmitral velocity. The square of the half time (delta t2) was highly correlated with delta P100 (r = 0.97), and the inverse of the half time (delta t-1) was correlated with MVA (r = 0.76). There was no significant correlation between delta P100 and diastolic descent rate of anterior mitral leaflet (DDR). The present study indicates that the half time is useful in estimating transmitral pressure gradient and MVA in mitral stenosis.

Am J Cardiol. 1986 Mar 1;57(8):634-8.

Effect of atrial fibrillation and mitral regurgitation on calculated mitral valve area in mitral stenosis.

Bryg RJ, Williams GA, Labovitz AJ, Aker U, Kennedy HL.

Forty-nine patients with mitral stenosis (MS) were studied by Doppler echocardiography and 2-dimensional (2-D) echocardiography to assess the ability of Doppler ultrasound to accurately measure mitral valve orifice area and to assess whether atrial fibrillation (AF) or mitral regurgitation (MR) affected the calculation. Twenty-four patients underwent cardiac catheterization. Mitral valve area by Doppler was determined by the pressure half-time method. Mean mitral valve area of all 49 patients by Doppler and 2-D echocardiography correlated well (r = 0.90). There was good correlation between Doppler and 2-D echocardiography in patients with pure MS in sinus rhythm (r = 0.88), in patients with MR (r = 0.93) and in patients with AF (r = 0.96). In the 7 patients with pure MS in sinus rhythm, there was good correlation between Doppler, 2-D echocardiography and cardiac catheterization (r = 0.95). In patients with either MR or AF, cardiac catheterization appeared to underestimate mitral valve orifice compared with both Doppler and 2-D echocardiography (p less than 0.05). Doppler echocardiography can estimate valve area in patients with MS regardless of the presence of MR or AF.

G Ital Cardiol. 1986 May;16(5):411-6.

Determination of stenotic mitral valve area using Doppler echocardiography. A comparison with hemodynamic studies.

Moro E, Roelandt J.

In order to assess the reliability of Doppler echocardiography in the determination of mitral valve area (MVA) 21 consecutive patients (pts) affected by rheumatic disease and mitral valve stenosis (MS) were analyzed by continuous wave doppler echocardiography (CWD). Cardiac catheterization (cath) was performed within 24 hours from echocardiographic examination. MVA by CWD was calculated with a computerized system from the "pressure half-time" (T1/2) using the equation: 220/T1/2 in cm2. MVA was calculated from cath data by applying the modified Gorlin formula. MVA determined by CWD ranged from 0.9 to 2.8 cm2 (mean 1.39 +/- 0.55). MVA determined by Gorlin formula ranged from 0.5 to 2.8 cm2 (mean 1.31 +/- 0.63). The correlation between CWD and cath was good (r = 0.93, SEE = 0.19 cm2, P less than 0.001). In conclusion this study indicates that CWD is quite accurate in estimation of MVA and can reliably discriminate the "critical" size of the orifice. CWD has the advantage of allowing MVA determination in patients with associated mitral regurgitation.

Z Kardiol. 1986 Oct;75(10):598-604.

Doppler sonography quantification of mitral valve stenosis in patients with and without mitral valve insufficiency

Kronik G, Pandi AS, Zangeneh M, Schmoliner R, Mosslacher H.

Fifty-three patients with mitral stenosis (MS) were examined by two dimensional (2DE) and Doppler echocardiography (Dop). Twenty-nine of them also had mitral insufficiency (MI) as judged by Dop. The mitral valve area (MVA) was calculated from Doppler using the "pressure half time" and was compared with MVA by 2 DE. There was a good correlation between both methods in all 53 patients (r = 0.88; SEE = 0.34 cm2) but also in the subgroups with pure MS (r = 0.86; SEE = 0.29 cm2) and MS + MI respectively (r = 0.90; SEE = 0.38 cm2). The accuracy and the reproducibility of the Doppler method was highly dependent on the severity of the stenosis. In 19 cases with mild MS (MVA by 2 DE greater than 1.5 cm2) the absolute difference between MVA 2 DE and Dop averaged 0.39 cm2. The difference between the maximal and minimal Doppler MVA which reflects the variability of this method averaged 0.65 cm2 in this group. In cases with significant MS (MVA by 2 DE less than or equal to 1.5 cm2) the average difference 2 DE -Dop and Dop max-Dop min was only 0.20 cm2 and 0.27 cm2 respectively. In patients with comparable degrees of stenosis additional MI did not adversely affect the accuracy of the Doppler method. We conclude that Doppler echo allows an accurate quantitation of mitral stenosis even in patients with associated MI.

Herz. 1986 Dec;11(6):323-6.

Doppler echocardiography determination of the pressure gradient and valve orifice area in mitral valve stenosis.

Kraus F, Dennig K, Bosiljanoff P, Rudolph W.

Pressure gradient and orifice area of stenosed mitral valves can be determined with Doppler echocardiography using the modified Bernoulli equation and the pressure half-time method, respectively (Figures 1 and 2). There was a close linear correlation between Doppler-echocardiographically determined pressure gradients and valve orifice areas with those obtained by invasive methods. In this study, in 85 patients with mitral stenosis of various severity, the valve orifice areas, as derived by the two methods respectively, correlated well (y = 0.89x + 0.15) with a correlation coefficient r = 0.96 and standard error of the estimate SEE = 0.12 cm2 (Figure 3). The correlation was not influenced by the prevailing cardiac rhythm, ventricular function, left ventricular mass or coexistent mitral or aortic regurgitation (Table 1). Accordingly, the Doppler echocardiographic method also appears applicable in the presence of concomitant mitral and aortic regurgitation which precludes an exact determination of valve orifice area with invasive methods. The Doppler echocardiographic method is currently so well validated that it can be regarded as a reliable noninvasive procedure for determination of the severity of mitral stenosis.

Am Heart J. 1987 Apr;113(4):868-73.

Doppler measurement of left atrial depressurization and mitral valve area in patients with suspected mitral stenosis: validation of a new method.

Pearlman JD, Gibson RS.

Atrial depressurization time measurement by Doppler ultrasound can be used to quantify stenotic mitral valve area. In this report, we present the results of a blinded trial comparing the standard Doppler method for "pressure half-time" (A) and another Doppler method we devised (B) for measurement of atrial depressurization time. Both methods were tested against valve area data from catheterization performed within 24 hours after Doppler echocardiography. Ten readers analyzed each of 10 Doppler profiles by methods A and B, in random order. After decoding, each of the 200 Doppler readings was compared to the catheterization result. Method B proved more accurate than method A by repeated measures analysis of variance (p less than 0.0001). Furthermore, method B took less than half as long to perform (p less than 0.0001). The methods presented herein provide a simple alternative means to follow the progression of mitral stenosis noninvasively and to determine optimal timing for surgery.

Br Heart J. 1987 Apr;57(4):348-55.

A comparison of the assessment of mitral valve area by continuous wave Doppler and by cross sectional echocardiography.

Loperfido F, Laurenzi F, Gimigliano F, Pennestri F, Biasucci LM, Vigna C, De Santis F, Favuzzi A, Rossi E, Manzoli U.

Transmitral pressure half time (PHT) was assessed by continuous wave Doppler in 44 patients with rheumatic mitral valve stenosis (14, pure mitral valve stenosis; 15, combined mitral stenosis and regurgitation; and 15 with associated aortic valve regurgitation). The mitral valve area, derived from transmitral pressure half time by the formula 220/pressure half time, was compared with that estimated by cross sectional echocardiography. The transmitral pressure half time correlated well with the mitral valve area estimated by cross sectional echocardiography. The correlation between pressure half time and the cross sectional echocardiographic mitral valve area was also good for patients with pure mitral stenosis and for those with associated mitral or aortic regurgitation. The regression coefficients in the three groups of patients were significantly different. Nevertheless, a transmitral pressure half time of 175 ms correctly identified 20 of 21 patients with cross sectional echocardiographic mitral valve areas less than 1.5 cm2. There were no false positives. The Doppler formula significantly underestimated the mitral valve area determined by cross sectional echocardiography by 28(9)% in 19 patients with an echocardiographic area greater than 2 cm2 and by 14.8 (8)% in 25 patients with area of less than 2 cm2. In thirteen patients with pure mitral valve stenosis Gorlin's formula was used to calculate the mitral valve area. This was overestimated by cross sectional echocardiography by 0.16 (0.19) cm2 and underestimated by Doppler by 0.13 (0.12) cm2. Continuous wave Doppler underestimated the echocardiographic mitral valve area in patients with mild mitral stenosis. The Doppler formula mitral valve area = 220/pressure half time was more accurate in predicting functional (haemodynamic) than anatomical (echocardiographic) mitral valve area.

Eur Heart J. 1987 May;8(5):484-9.

A study of the correlation between Doppler and cross-sectional echocardiography in the determination of the mitral valve area.

Friart A, Vandenbossche JL, Kostucki W, Englert M.

Fifty-five consecutive adult patients with mitral stenosis (MS) were investigated by Doppler echocardiography, to assess the severity of MS. The measurement of mitral valve area (MVA) by cross-sectional echocardiography (CSE) was considered as the reference method, because catheterization data are often inadequate when combined lesions are present. Doppler MVA was calculated from apical mitral flow using the pressure half-time method. Adequate Doppler recordings (52 on 55) were easier to obtain than adequate CSE images[47]. The correlation between both methods was excellent (r = 0.90, SEE: 0.42 cm2) despite systematic underestimation of MVA by Doppler versus CSE. From our data, the following regression equation could be drawn, providing MVA from Doppler measurements: MVA = 250 (pressure half-time)-1 +0.15, where the area is in cm2 and half-time in ms. Both severe and mild MS were identified by Doppler with enough accuracy for clinical use. Reproducibility, inter and intraobserver variability were better for Doppler than for CSE. We conclude that Doppler seems particularly suitable for noninvasive quantification of MS and for patient follow-up.

Chest. 1987 Jul;92(1):27-30.

Role of exercise Doppler echocardiography in isolated mitral stenosis.

Sagar KB, Wann LS, Paulson WJ, Lewis S.

This study reports the role of Doppler ultrasound during exercise for assessment of patients with mitral stenosis. Doppler echocardiography was performed at rest and during symptom-limited supine bicycle exercise in ten patients with isolated mitral stenosis. The mean mitral valvular gradient was calculated using modified Bernoulli's equation, and the mitral valvular area was estimated from the equation, 220/pressure half-time. During exercise the heart rate increased from 74 +/- 14 beats per minute (mean +/- SD) at rest to 110 +/- 8 beats per minute (p less than 0.001) during exercise. The mean mitral gradient increased from 9 +/- 5 mm Hg at rest to 18 +/- 7 mm Hg (p less than 0.01) during exercise. The mitral pressure half-time decreased from 225 +/- 62 msec at rest to 190 +/- 42 msec during peak exercise (p less than 0.005). This corresponded to a reduction of 15 percent. The estimated mitral valvular area increased from 1.0 +/- 0.4 sq cm at rest to 1.2 +/- 0.3 sq cm at peak exercise (p less than 0.005). In conclusion, Doppler echocardiography can be used to evaluate patients with mitral stenosis, with the response of the mitral valvular gradient being the index of obstruction; however, caution should be used in applying the mitral pressure half-time for estimation of the mitral valvular area at high heart rates and flows.

Am J Cardiol. 1987 Aug 1;60(4):322-6.

Effect of aortic regurgitation on the assessment of mitral valve orifice area by Doppler pressure half-time in mitral stenosis.

Grayburn PA, Smith MD, Gurley JC, Booth DC, DeMaria AN.

Evaluation of the severity of mitral stenosis by continuous-wave Doppler pressure half-time measurement is now well established. However, few data exist regarding the effect of aortic regurgitation (AR) on the validity of this method. Therefore, 73 patients were studied in whom cardiac catheterization and Doppler echocardiographic examinations were performed. Mitral valve orifice area was determined by the Gorlin equation, 2-dimensional echocardiography and Doppler pressure half-time. Doppler pressure half-time and catheterization estimates of mitral valve area correlated well (r = 0.85) in patients without significant mitral regurgitation. This correlation was maintained in patient subgroups with and without significant (at least 2+) AR (r = 0.86 and 0.83, respectively). Similarly, Doppler and 2-dimensional echocardiographic assessment of mitral valve area showed a strong correlation (r = 0.84). Again, the correlation between the 2 methods was similar in patients with and without significant AR (r = 0.86 and 0.82, respectively). Thus, Doppler pressure half-time estimates of mitral valve orifice area are accurate even in patients with AR.

Am J Cardiol. 1987 Aug 1;60(4):327-32.

Comparison of two-dimensional and Doppler echocardiography and intracardiac hemodynamics for quantification of mitral stenosis.

Gonzalez MA, Child JS, Krivokapich J.

Forty-three patients with mitral stenosis (MS) were studied to assess the relation of catheter-derived pressure gradient half-time (P 1/2), mitral valve areas (calculated by the Gorlin formula and 2-dimensional echocardiography [2-D echo]) to mitral valve areas derived from Doppler pressure half-time (T 1/2) in order to establish an accurate line-drawing method in nonlinear velocity tracings and to revalidate the use of the empiric constant of 220 ms as the T 1/2 that predicts a 1.0-cm2 mitral valve area. Mitral valve area could be quantified by 2-D echo in 39 of 43 patients and by Doppler in 31 of 34 patients, for a success rate of 91%. A reliable technique for measuring Doppler T 1/2 in nonlinear Doppler velocity tracings was a "mid-diastolic" line-drawing method, validated with the "anatomic" mitral valve area by 2-D echo (r = 0.89) and with the "hemodynamic" mitral valve area by the Gorlin formula (in pure MS without regurgitation) (r = 0.95). By both Doppler T 1/2 and hemodynamic P 1/2, the use of 220 ms to predict a mitral valve area of 1.0 cm2 was validated. Each T 1/2 and P 1/2 had an exponential inverse relation to the mitral valve area by the Gorlin formula in pure MS. Doppler and 2-D echocardiographic quantification of MS are complementary. Reliable measurement of T 1/2 in nonlinear velocity tracings is achieved by a mid-diastolic line-drawing method and use of the equation 220 ms/T 1/2 = mitral valve area accurately quantifies MS.

J Am Coll Cardiol. 1987 Oct;10(4):923-9.

Doppler mitral pressure half-time: a clinical tool in search of theoretical justification.

Thomas JD, Weyman AE.

Noninvasive Cardiac Laboratory, Massachusetts General Hospital, Boston 02114.

The Doppler determination of the mitral pressure half-time has gained widespread acceptance as a reliable estimate for mitral valve area, despite little theoretical basis for its "independence" of other hemodynamic variables. A simple model of the left atrium and mitral valve has been developed and a governing equation derived from fluid dynamics fundamentals. Solution of this equation indicates that the pressure half-time should vary inversely with mitral valve area, but also proportionally to net left atrial and ventricular compliance and to the square root of the peak transmitral gradient. This complex relation is apparently masked in the typical clinical situation because pressure and compliance tend to change in opposite directions, thereby partly offsetting each other. In several clinical settings, such as balloon mitral valvotomy, left ventricular hypertrophy and aortic regurgitation, changes in initial pressure and compliance may be large enough to alter the relation between mitral area and pressure half-time. This study reviews the development of the pressure half-time concept, presents an overall method for studying mitral valve flow using mathematical modeling and describes the effects of factors other than mitral valve area on pressure half-time.

Circulation. 1988 Jan;77(1):78-85.

Value and limitations of Doppler echocardiography in the quantification of stenotic mitral valve area: comparison of the pressure half-time and the continuity equation methods.

Nakatani S, Masuyama T, Kodama K, Kitabatake A, Fujii K, Kamada T.

Cardiovascular Division, Osaka Police Hospital, Japan.

Two Doppler methods, the pressure half-time method proposed by Hatle and the method based on the equation of continuity, were used to estimate stenotic mitral valve area noninvasively, and the accuracy of these methods was examined in patients with and without associated aortic regurgitation. Mitral valve area determined at catheterization by the Gorlin formula was used as a standard of reference. The study population consisted of 41 patients with mitral stenosis, and 20 of the 41 patients had associated aortic regurgitation. According to the equation of continuity, mitral valve area was determined as a product of aortic or pulmonic annular cross-sectional area and the ratio of time velocity integral of aortic or pulmonic flow to that of the mitral stenotic jet. Mitral valve area was determined by the pressure half-time method as 220/pressure half-time, the time from the peak transmitral velocity to one-half the square root of the peak velocity on the continuous-wave Doppler-determined transmitral flow velocity pattern. The pressure half-time method tended to overestimate catheterization measurements, and the correlation coefficient for this relation was .69 (SEE = 0.44 cm2). The correlation coefficient improved to .90 when the patients with associated aortic regurgitation were excluded. Mitral valve areas determined by the continuity equation method correlated well with catheterization measurements at a correlation coefficient of .91 (SEE = 0.24 cm2), irrespective of the presence of aortic regurgitation. The ratio of the time-velocity integral or aortic or pulmonic flow to the time-velocity integral of mitral stenotic jet also correlated well with mitral valve area determined by catheterization at a correlation coefficient of .84 (SEE = 0.10).

Herz. 1988 Apr;13(2):100-9.

Doppler echocardiographic findings before and after balloon catheter valvuloplasty in mitral stenosis.

Dennig K, Dacian S, Rudolph W.

Klinik fur Herz-und Kreislauferkrankungen, Deutsches Herzzentrum Munchen.

This study was undertaken to analyze the diagnostic value of Doppler echocardiographic determination of pressure gradient and valve orifice area for the evaluation of balloon valvuloplasty in mitral stenosis as well as the echocardiographic assessment of calcification, leaflet motion and the subvalvular apparatus for characterization of the most favorable morphologic prerequisites for this procedure. Doppler echocardiographic studies were performed in 24 patients with mitral stenosis, 21 women and three men, age range from 29 to 79 years, mean age 55 years, one day before and after balloon valvuloplasty and the results were compared with invasively-determined hemodynamic measurements. The Doppler echocardiographic determination of the mean pressure gradient before and after balloon valvuloplasty was carried out with the modified Bernoulli equation from the velocity profile of the stenotic jet and calculation of the mitral valve orifice area using the pressure half-time method. Echocardiographic assessment of valve morphology and motion was based on two-dimensional echocardiographic cross-sectional images. Calcification, as observed in the parasternal cross-sectional image, was classified as absent (grade 0), slight to moderate (grade 1) or severe (grade 2). Motion of the valve leaflets, as judged from the apical four- and two-chamber views, was assigned one of five grades taking into consideration the motion of the bodies of both leaflets from the systolic baseline position as less than 10 degrees, between 10 and 45 degrees and more than 45 degrees. The subvalvular apparatus, that is the chordae and the papillary muscles, were graded as unremarkable (grade 0), slightly altered (grade 1) and markedly altered (grade 2). Using a score derived by adding the grade of these three criteria, a formal value between 0 and 8 was calculated. Hemodynamic measurements were carried out with standard techniques employing simultaneous registrations of left atrial and left ventricular pressure for evaluation of the mean diastolic pressure gradient. Determination of the stroke volume was based on biplane left ventriculograms using Simpson's rule. The valve orifice area was calculated according to the Gorlin formula. Dilatation was carried out with a Bifoil (12F, balloon diameter 2 X 19 mm) or Trefoil (10F, 3 X 12 mm) valvuloplasty catheter. After PTVP, on comparison of the Doppler-echocardiographically determined pressure gradient (5.7 +/- 1.9 mm Hg) with that determined invasively (6.4 +/- 3.2 mm Hg) there was a moderate correlation (n = 19, r = 0.74, SEE = 1.3 mm Hg) where the noninvasively-determined values, in general, were smaller.

Eur Heart J. 1988 Sep;9(9):1010-7.

Influence of aortic regurgitation on the assessment of the pressure half-time and derived mitral-valve area in patients with mitral stenosis.

Moro E, Nicolosi GL, Zanuttini D, Cervesato E, Roelandt J.

Erasmus University and Academic Hospital Dijzigt, Rotterdam, The Netherlands.

The influence of aortic regurgitation on the Doppler assessment of pressure half-time (T1/2) and on the derived calculation of the mitral-valve area has not yet been adequately evaluated in patients with mitral stenosis and associated aortic regurgitation. Therefore this study was undertaken to verify the accuracy of the T1/2 method for the noninvasive estimation of mitral-valve area in patients with mitral stenosis and associated aortic regurgitation. Data were obtained from 31 selected patients who underwent cardiac catheterization within 24 h of the noninvasive examination. From the Doppler velocity curve, T1/2 was calculated as the interval between the peak transmitral velocity and velocity/ square root of 2. Mitral-valve area was measured from the T1/2 with a computerized system using the equation: 220/T1/2, in cm2. Calculation of the mitral-valve area at catheterization was derived applying the modified Gorlin formula. Mean mitral-valve area, as determined at catheterization, ranged from 0.5 to 2.8 cm2 (1.3 +/- 0.6). Mean mitral-valve area, as calculated by continuous-wave Doppler, ranged from 0.7 to 2.7 cm2 (1.5 +/- 0.6). Linear-regression analysis of data revealed a good correlation between Gorlin and Doppler measurements of the mitral-valve area (r = 0.90, SEE = 0.28 cm2, P less than 0.001, y = 1.0x + 0.2). Doppler showed a systematic overestimate of the mitral-valve area (26%) in patients with mitral stenosis and aortic regurgitation as compared to the Gorlin formula. The overestimate of continuous-wave Doppler was even greater (39%) in a subgroup of patients with 2+ or 3+ angiographic aortic regurgitation.

J Am Soc Echocardiogr. 1988 Sep-Oct;1(5):313-21.

Pressure half-time does not always predict mitral valve area correctly.

Loyd D, Ask P, Wranne B.

Department of Applied Thermodynamics and Fluid Mechanics, Linkoping University, Sweden.

A theory is presented elucidating factors that influence the pressure half-time. By combining the Bernoulli and continuity equations and making certain assumptions about the shape of the atrioventricular pressure difference decay, it can be shown that valve area, volume transported across that area, and initial pressure difference influence the pressure half-time according to a formula in which the pressure half-time is related to V/(Ao square root of delta po), where V is the transported volume across the orifice with the area Ao, and delta po is the initial pressure difference across that area. In a subsequent hydraulic model experiment pressure half-time was determined for three different hole areas, with various initial volumes and initial pressure gradients. We did not obtain a unique relation between the pressure half-time and area. Instead the results supported our theory, and we found a close linear relationship between area and V/(T0.5 square root of delta po) (correlation coefficient [r] = 0.998), as predicted in the theory (T0.5 = pressure half-time). Clinical examples in which the pressure half-time may be misleading in the assessment of severity of mitral stenosis are presented.

Circulation. 1988 Oct;78(4):980-93.

Inaccuracy of mitral pressure half-time immediately after percutaneous mitral valvotomy. Dependence on transmitral gradient and left atrial and ventricular compliance.

Thomas JD, Wilkins GT, Choong CY, Abascal VM, Palacios IF, Block PC, Weyman AE.

Noninvasive Cardiac Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114.

Mitral pressure half-time (T1/2) is widely used as an independent measure of mitral valve area in patients undergoing percutaneous mitral valvotomy. However, fluid dynamics theory predicts T1/2 to be strongly dependent on chamber compliance and the peak transmitral gradient, which are variables that change dramatically with valvotomy. These theoretical predictions were tested in an in vitro model of the left heart where valve area, chamber compliance, and initial gradient were independently adjusted. Measured T1/2 was observed to vary inversely with orifice area and directly with net chamber compliance and the square root of the initial pressure gradient. Theoretical predictions of T1/2 agreed with observed values with r = 0.998. To test this theory in vivo, the hemodynamic tracings of 18 patients undergoing mitral valvotomy were reviewed. Predictions were made for T1/2 assuming dependence only on valve area; these showed some correlations before valvotomy (r = 0.48-0.64, p less than 0.05) but none after valvotomy (r = 0.05-0.28, p = NS). Predictions for T1/2 based on the theoretical derivation (and thus including compliance and pressure in their calculation) were much better: before valvotomy, r = 0.93-0.96, p less than 0.0001; after valvotomy, r = 0.52-0.66, p less than 0.05. These data indicate that T1/2 is not an independent inverse measure of mitral valve area but is also directly proportional to net chamber compliance and the square root of the initial transmitral gradient. These other factors render T1/2 an unreliable measure of mitral valve area in the setting of acute mitral valvotomy.

J Am Coll Cardiol. 1989 Mar 1;13(3):594-9.

Reassessment of valve area determinations in mitral stenosis by the pressure half-time method: impact of left ventricular stiffness and peak diastolic pressure difference.

Karp K, Teien D, Bjerle P, Eriksson P.

Department of Clinical Physiology, University Hospital, Umea, Sweden.

Estimation of the orifice area is of major importance in the timing of valve dilation or surgery in patients with mitral stenosis. Determination of the area has traditionally been accomplished at cardiac catheterization by the Gorlin equation. The valve area can also be estimated noninvasively with Doppler echocardiographic measurements of the pressure half-time, which is inversely proportional to the area. This method has gained widespread acceptance, but its accuracy has recently been questioned and factors other than reduction of orifice area appear to modify the pressure half-time. In the present study, the influence of left ventricular stiffness (defined as diastolic pressure rise per milliliter of mitral flow) and peak atrioventricular pressure difference on the pressure half-time was examined both in a hydraulic model and by review of data from 35 patients with mitral stenosis. Left ventricular stiffness less than 0.13 mm Hg/ml was considered normal. In the model study, the orifice area correlated only moderately with inverted pressure half-time (1/PHT) (r = 0.67). By multiple linear regression, inverted pressure half-time was shown to be dependent on valve area, chamber stiffness and peak pressure difference (R = 0.89), area and stiffness being most important (R = 0.85). In the clinical study, an increased ventricular stiffness was found in 22 of the 35 patients. The pressure half-time method overestimated the Gorlin-derived area by an average of 72% in these patients compared with only 10% in 13 patients with normal stiffness (p less than 0.001).

Clin Cardiol. 1989 Nov;12(11):629-33.

Doppler echocardiographic assessment of transmitral gradients and mitral valve area before and after mitral valve balloon dilatation.

Dev V, Singh LS, Radhakrishnan S, Saxena A, Shrivastava S.

Department of Cardiology, All India Institute of Medical Sciences, New Delhi.

This is a comparative study of 60 sets of observations of mitral valve end-diastolic gradient, mean diastolic gradient, and mitral valve area obtained by Doppler echocardiography and cardiac catheterization. The studies were performed in 28 patients, 16 of whom underwent mitral valve balloon valvuloplasty. These 16 patients had studies performed before, immediately after valvuloplasty, and one week later. Thus 28 studies were performed before or without valvuloplasty (Group I) and 32 after valvuloplasty (Group II). The time interval between Doppler echocardiography and cardiac catheterization was less than 24 hours in 44 studies and 24 to 72 hours in 16 studies. In Doppler echocardiography the gradients were obtained by simplified Bernoulli's equation and the mitral valve area by pressure half-time method. There was excellent correlation between end-diastolic gradients (r = 0.96, p less than 0.001) and mean diastolic gradients (r = 0.92, p less than 0.001) measured by the two techniques. A statistically significant correlation also existed in the mitral valve area values (r = 0.53, p less than 0.005). On separate analysis Group I showed excellent correlation for all three variables (r values of 0.90, 0.87, and 0.82 for end-diastolic gradients, mean-diastolic gradients, and mitral valve area, respectively). Group II also showed excellent correlation of end-diastolic gradients (r = 0.80) and mean diastolic gradients (r = 0.87), but poor correlation of the mitral valve areas (r = 0.17; p = NS) by the two techniques. Doppler echocardiography can accurately measure transmitral gradients both before and after valvuloplasty.

J Cardiol. 1990;20(4):897-903.

Mitral valve function after open mitral commissurotomy: assessment by Doppler echocardiography.

Kamiya H, Ishimitsu T, Hiranuma Y, Sugishita Y, Ito I.

Department of Internal Medicine, University of Tsukuba.

To evaluate mitral valve function and its long-term outcome after open mitral commissurotomy (OMC), we examined 39 patients using Doppler echocardiography. There were 13 males and 26 females; who were examined a total of 83 times after the surgery at about one year intervals (seven to 240 months, averaging 78 months). We measured the velocity of transmitral blood flow using the continuous wave Doppler method (CWD), and the transmitral pressure half time (PHT), mean velocity (m V) and peak velocity (pV) were calculated. The presence and severity of mitral regurgitation (MR) were assessed by color flow mapping. 1. PHT gradually increased and significantly correlated (r = 0.63, p less than 0.001) with the months passed after OMC. The regression line of PHT in postoperative months was "PHT = 0.70 x PMo + 83" (PMo = postoperative months). The mV and pV tended to increase gradually, but did not significantly correlate with the months passed after the surgery. 2. Among the 39 patients, 28 (72%) had MR, and their severity was classified as 1+ in two, 2+ in 19, 3+ in six and 4+ in one. Among 21 patients who had no MR before OMC, MR appeared in 12 (57%), and its severity was classified as 1+ in one, 2+ in nine and 3+ in two. All five patients with preoperative MR had MR postoperatively, and their severity was classified as 1+ in one, 2+ in two and 3+ in two. The presence of the preoperative MR of the remaining 13 patients was unknown.

Am Heart J. 1990 Jan;119(1):121-9.

Comparison of hemodynamic pressure half-time method and Gorlin formula with Doppler and echocardiographic determinations of mitral valve area in patients with combined mitral stenosis and regurgitation.

Fredman CS, Pearson AC, Labovitz AJ, Kern MJ.

Department of Internal Medicine, St. Louis University School of Medicine, MO 63110-0250.

Mitral valve area determined by the Gorlin formula in patients with combined mitral stenosis and regurgitation underestimates the true orifice size. Recent data suggest Doppler ultrasound and two-dimensional echocardiography more accurately estimate the mitral valve area in patients with mixed mitral valvular disease. This study assessed the accuracy of an alternate method, the hemodynamic pressure half-time method, for mitral valve area determination in such patients. In 22 patients, 28 separate mitral valve areas were calculated by the hemodynamic pressure half-time method, the Gorlin formula, and the Gorlin formula corrected for mitral regurgitation, and were compared with results calculated by the Doppler pressure half-time method. Six patients were studied both before and after balloon mitral valvuloplasty. In addition, mitral valve areas calculated by all four methods were compared with results obtained by planimetry in 15 patients with technically optimal echocardiograms. The mitral valve areas determined by hemodynamic pressure half-time corretated closely with the valve areas determined by Doppler (r = 0.90), whereas mitral valve areas determined by the Gorlin formula (both without and with correction for mitral regurgitation) did not correlate as well with the Doppler-estimated valve areas (r = 0.47 and r = 0.56, respectively). Correlation between the Doppler-derived mitral valve areas and the planimetered valve areas was also good (r = 0.84), as was that between the mitral valve areas calculated by hemodynamic pressure half-time and those calculated by planimetry (r = 0.78).

Cardiologia. 1990 Feb;35(2):143-7.

Doppler echocardiography in the functional evaluation of patients with pure mitral valve stenosis.

Tartarini G, Balbarini A, Baglini R, Di Marco S, Mengozzi G, Passaglia C, Mariotti R, Mariani M.

Istituto di Cardiologia, Universita degli Studi, Pisa.

To evaluate the utility of echo-Doppler (ED; PW, CW and color), 67 patients affected by pure mitral stenosis (20 M, 47 F, mean age 52 years) were submitted to ED examination. Right and left cardiac catheterization were performed in 20 patients within 24 hours before ED. Mitral area obtained by Doppler method (Hatle's formula) correlated highly with both echo-2 dimensional and hemodynamic area (r = 0.93, p less than 0.001; r = 0.95, p less than 0.001 respectively). It was possible to calculate systolic pulmonary pressure, in patients with tricuspid incompetence, (43.9 +/- 14.9 mmHg, range 25-80) which correlated significantly (r= 0.95, p less than 0.001) with hemodynamic data (40.2 +/- 12.7 mmHg, range 20-70). The left atrial-left ventricular pressure gradient was 15.6 +/- 6.9 mmHg, range 6-32; the mean pressure gradient was 8.4 +/- 3.7 mmHg, range 3-17; the pressure half time 170.2 +/- 62.3 ms, range 83-330. We observed different types of direction of transmitral jets: centrally directed (n = 34); forward antero-lateral wall (n = 28); toward interventricular septum (n = 5). The transmitral jets presented 4 different appearances: scimitar-shaped (n = 28); candle flame (n = 24); mushroom (n = 9); double-jets (n = 6). No correlation was observed between the different types of transmitral jets (direction and appearance) and the parameters obtained by Doppler (PW and CW): velocities, pressure half-time, gradients. Thus, Doppler echocardiography permits a complete anatomic and functional evaluation of patients with pure mitral stenosis. We have not observed any correlation between the hemodynamic data and the different types of transmitral jets visualized by color Doppler.

Rev Esp Cardiol. 1990 Feb;43(2):87-92. Related Articles, Links

Calculation of the mitral valve area using Hatle's method. Effect of the preload change induced by nitrates.

Alonso Gomez AM, Rodriguez JA, Torres A, Villaroel MT, Cordo JC, Diaz A, Martinez Ferrer JB, Camacho I.

Unidad Funcional de Cardiologia, Hospital Txagorritxu, Vitoria-Gasteiz. >P> The aim of the present study was to assess the effect of changes in preload induced by nitrates on calculated mitral valve area by Doppler pressure half-time. Forty patients (mean age 51 +/- 10 years), 23 with mitral stenosis, ten with mechanical prosthesis and seven with bioprosthesis were studied by Doppler echocardiography. Twelve were in sinus rhythm and 28 had atrial fibrillation. Mitral valve area by Doppler pressure half-time, peak and mean mitral gradient and pulmonary artery systolic pressure were measured before and after isosorbide dinitrate (5 mg) or nitroglycerin (0.4 mg). The nitrates produced a significant reduction of pre-load in total group (p less than 0.001) but did not change the mitral valve area (1.9 +/- 0.8 to 1.9 +/- 0.8). The subsets of patients with size valvular area (greater than 2 cm2, less than 2 cm2, less than 1.5 cm2, mechanical prosthesis, bioprosthesis, sinus rhythm and atrial fibrillation) had an insignificant change in mitral valve area after administration of nitrates. We conclude that the mitral valve area by Doppler pressure half-time method do not modify in different conditions of preload. These findings remain in patients with prosthesis, different sizes of mitral valve area and atrial fibrillation.

Eur Heart J. 1990 Jul;11(7):592-600.

The reproducibility of continuous wave Doppler measurements in the assessment of mitral stenosis or mitral prosthetic function: the relative contributions of heart rate, respiration, observer variability and their clinical relevance.

Rijsterborgh H, Mayala A, Forster T, Vletter W, van der Borden B, Sutherland GR, Roelandt J.

Interuniversity Cardiology Institute of The Netherlands, Rotterdam.

The reproducibility of continuous wave Doppler echocardiographic measurements of transmitral diastolic flow velocity were studied in terms of bias and random error in 40 patients with either mitral stenosis or a Bjork-Shiley mitral valve prosthesis. Twenty-seven patients were in sinus rhythm; 13 patients had atrial fibrillation. Intra- and interobserver differences in bias were small for the Doppler parameters studied i.e. early peak velocity (0.6% vs 3.6%), mean diastolic velocity (1.1% vs 8.6%),mean temporal velocity (2.3% vs 14.5%) and pressure half-time (2.7% vs 4.8%). The overall random error of the measurements (in terms of twice the standard deviation) was estimated separately in patients in sinus rhythm and atrial fibrillation: early peak velocity 5.6% and 9.2%, respectively, mean diastolic velocity 9.4% and 22%, mean temporal velocity 8.6% and 19% and pressure half-time 34% and 46%. The relative contributions to the overall random error of observer variation, heart rate dependency and respiratory variation were also studied. Heart rate dependency was demonstrated for both the mean diastolic velocity and the pressure half-time. Respiratory variation was found in the early peak velocity. From the results of this study the number of measurements to reduce the random error of the final average could be determined. Our results indicate that for the measurements in which a respiratory effect is present it is advisable to average the measurements taken over complete respiratory cycles.

Zhonghua Xin Xue Guan Bing Za Zhi. 1990 Aug;18(4):207-9, 253.

Value and limitations of the pressure halftime method for quantitating the mitral valve area in mitral stenosis.

Zhang Y.

Affiliated Hospital, Shandong Medical University, Jinan.

To evaluate the accuracy of the pressure half-time (PHT) method in predicting the anatomical mitral valve area (Aa) in mitral stenosis, Doppler echocardiography was performed in 42 cases with mitral stenosis within 48 hours before mitral valve replacement. The diastolic mitral flow velocities were recorded by the continuous wave Doppler technique, and PHT and the derived mitral valve area (Ad) were measured by a computer system from the Doppler spectrum. Aa was measured from a photograph of the mitral valve excited en bloc at surgery. The comparison between Aa and Ad yielded a good correlation (r = 0.85). However, Ad significantly underestimated Aa (P less than 0.001) in cases with combined mitral stenosis and regurgitation, and significantly overestimated Aa in cases with combined mitral and aortic lesions. There was also a large scatter of data obtained by the two measurements (SEE = 0.41 cm2). It is concluded that the PHT method can predict Aa in isolated mitral stenosis with anacceptable accuracy but is of only limited value in combined mitral stenosis and regurgitation or combined mitral and aortic valve lesions.

J Am Coll Cardiol. 1990 Aug;16(2):396-404.

Aortic regurgitation shortens Doppler pressure half-time in mitral stenosis: clinical evidence, in vitro simulation and theoretic analysis.

Flachskampf FA, Weyman AE, Gillam L, Liu CM, Abascal VM, Thomas JD.

Noninvasive Cardiac Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston 02114.

Mitral valve areas determined by Doppler pressure half-time were compared with areas obtained by planimetry in two groups of patients with mitral stenosis: 24 patients without aortic regurgitation and 32 patients with more than grade 1 aortic regurgitation. The severity of aortic regurgitation was assessed by color flow mapping; 17 patients had grade 2, 10 had grade 3 and 5 had grade 4 aortic regurgitation. Regression equations for pressure half-time area versus planimetry mitral valve area were calculated separately for the aortic regurgitation (r = 0.88) and the nonaortic regurgitation group (r = 0.86); analysis of covariance revealed a significant (p less than 0.001) difference between the two groups leading to overestimation of planimetry area by the pressure half-time method in the aortic regurgitation group. The mitral valve areas in the group without regurgitation were best calculated with the expression 239/T1/2 (r = 0.77) as compared with a best fit of 195/T1/2 (r = 0.85) for the aortic regurgitation group. To elucidate the mechanisms affecting pressure half-time in aortic regurgitation, an in vitro model of mitral inflow in the presence of varying regurgitant volumes and different ventricular chamber compliances was used. Aortic regurgitation shortened directly measured pressure half-time proportional to the regurgitant fraction but an increase in left ventricular compliance could offset this effect. Finally, in a mathematic model of mitral inflow the competing effects of aortic regurgitation and chamber compliance could be confirmed. In conclusion, aortic regurgitation results clinically in a significant net shortening of pressure half-time leading to mitral valve area overestimation. However, the effect is moderate and individually unpredictable because of changes in chamber compliance.

Am J Cardiol. 1990 Sep 1;66(5):614-20.

Analysis of different methods of assessing the stenotic mitral valve area with emphasis on the pressure gradient half-time concept.

Wranne B, Ask P, Loyd D.

Department of Clinical Physiology, University of Linkoping, Sweden.

There are 2 different theoretical models that analyze factors influencing the transmitral pressure gradient half-time (T1/2), defined as the time needed for the pressure gradient to reach half its initial value. In this report the models and the assumptions inherent in them were summarized. One model includes left heart chamber compliance, the other does not. Although the models at a superficial glance seem to be contradictory, the conclusions drawn from them are similar: i.e., T1/2 is influenced not only by valve area, but also by initial maximal pressure gradient and by flow. Different clinical situations in which the T1/2 method for valve area estimation has been shown not to work are analyzed in the 2 models. It is concluded that these models have contributed to our understanding of the T1/2 concept and when it should not be used. We also advocate use of the continuity equation in these situations, since no assumptions then need be made.

Am J Cardiol. 1991 Jan 15;67(2):162-8.

Effect of mitral regurgitation and volume loading on pressure half-time before and after balloon valvotomy in mitral stenosis.

Wisenbaugh T, Berk M, Essop R, Middlemost S, Sareli P.

Baragwanath Hospital, Johannesburg, South Africa.

Doppler pressure half-time (PHT) is frequently used to assess mitral valve area (MVA), but the reliability of PHT has recently been challenged, specifically in the setting of balloon mitral valvotomy when hemodynamics have been abruptly altered. The effect of volume loading both before and after balloon mitral valvotomy on computation of MVA by Gorlin and by PHT in 18 patients with high-fidelity micromanometer measurements of left atrial and left ventricular pressure was therefore examined. Echocardiographic MVA increased from 0.91 +/- 0.15 to 1.97 +/- 0.42 cm2 after valvotomy. Volume loading produced significant increases in left atrial pressure (16 to 23 before and 12 to 20 mm Hg after valvotomy), in cardiac output (3.7 to 4.1 before and 3.9 to 4.6 liters/min after valvotomy), and in mitral valve gradient (11 to 14 before and 5 to 7 mm Hg after valvotomy). These hemodynamic changes were associated with modest but significant decreases in PHT and increases in MVA estimated by 220/PHT (0.66 to 0.81 before and 1.64 to 1.96 cm2 after valvotomy), whereas the MVA by Gorlin was not affected in a consistent fashion by volume loading (0.85 to 0.89 before and 1.66 to 1.69 cm2 after valvotomy). The correlation between Gorlin MVA and 220/PHT was only fair (r = 0.73, p less than 0.001) and was significantly poorer among patients with greater than 1+ mitral regurgitation (r = 0.72) than among those with less or no regurgitation (r = 0.79) (p = 0.001 by analysis of covariance for mitral regurgitation effect).

Am Heart J. 1991 Feb;121(2 Pt 1):480-8.

Value and limitations of Doppler pressure half-time in quantifying mitral stenosis: a comparison with micromanometer catheter recordings.

Smith MD, Wisenbaugh T, Grayburn PA, Gurley JC, Spain MG, DeMaria AN.

Division of Cardiovascular Medicine, University of Kentucky College of Medicine, Lexington.

The purpose of this study was to compare the Doppler and catheterization pressure half-time methods of estimating mitral valve area with valve areas obtained by the Gorlin equation in a group of patients with clinically significant mitral stenosis. Data were analyzed from 67 consecutive patients who were undergoing continuous-wave Doppler examination and catheterization with micromanometer catheters. Doppler pressure half-time was calculated as the interval between peak transmitral velocity and velocity divided by the square root of 2, as measured from the outer border of the spectral envelope. Doppler mitral valve area (MVA) was obtained with the equation: MVA = 220 divided by pressure half-time. For catheterization data, the pressure half-time was measured directly from simultaneously recorded left ventricular and left atrial pressure (18 patients) or pulmonary capillary wedge pressure (49 patients). The catheterization half-time was taken as the time required for the peak pressure gradient to fall to one half of the initial value. Calculations of the mitral valve area at catheterization were obtained by the Gorlin equation with pressure gradient and cardiac output determinations. Mitral valve area as determined by the Gorlin equation for all cases ranged from 0.4 to 2.0 (mean = 1.03 +/- 0.37) cm2. Linear regression analysis that compared cardiac catheterization and Doppler half-times yielded r = 0.68. For the subgroup of patients with sinus rhythm, the correlation improved to r = 0.76.

Am Heart J. 1991 Feb;121(2 Pt 1):488-93.

Effect of severe pulmonary hypertension on the calculation of mitral valve area in patients with mitral stenosis.

Tabbalat RA, Haft JI.

Department of Cardiology, St. Michael's Medical Center, Newark, NJ 07102.

We studied 50 consecutive patients with mitral valve stenosis (MS) by cardiac catheterization and Doppler echocardiography to assess whether the presence of severe pulmonary hypertension affected the calculation of valve area by Doppler pressure half-time method and by the Gorlin formula using pulmonary capillary wedge pressure as an index of left atrial pressure. Patients with severe mitral regurgitation were excluded. In patients with pulmonary artery systolic pressure (PAS) less than 70 mm Hg (n = 33), there was good correlation between the mitral valve area derived from Doppler echocardiography and from cardiac catheterization (r = 0.85). However, in patients with PAS greater than or equal to 70 mm Hg (n = 17), this correlation was not as good (r = 0.57). In these 17 patients, the Gorlin formula tended to underestimate the valve orifice area (mean valve area 0.85 +/- 0.49 and 1.06 +/- 0.46 cm2 by catheterization and by Doppler respectively, p = NS). Direct measurement of the valve area by two-dimensional echocardiography was possible in 12 of the 17 patients and correlated well with Doppler values (r = 0.91). Hence in the presence of severe pulmonary hypertension, Doppler pressure half-time estimation of mitral valve area is more accurate than is catheterization-derived valve area, using the wedge pressure and the Gorlin formula.

J Am Coll Cardiol. 1991 Jul;18(1):85-92.

Comment in: J Am Coll Cardiol. 1992 Sep;20(3):750.

Application of Doppler color flow imaging to determine valve area in mitral stenosis.

Kawahara T, Yamagishi M, Seo H, Mitani M, Nakatani S, Beppu S, Nagata S, Miyatake K.

Cardiology Division of Medicine, National Cardiovascular Center, Osaka, Japan.

This study was undertaken to examine whether Doppler color flow imaging could accurately estimate the valve area in mitral stenosis. Doppler color flow assessments were performed in both an in vitro model and in 30 patients with mitral stenosis undergoing cardiac catheterization. In the experimental Doppler study using a circuit model, color jet width correlated well with actual orifice diameter (r = 0.99). In the clinical Doppler study, the mitral valve orifice was assumed to be elliptic and the mitral valve area was calculated from the following equation: (pi/4) (a x b), where a = color jet width at the mitral valve orifice in the apical long-axis view (short diameter) and b = the width in the 90 degrees rotated view (long diameter). Mitral valve area was also determined by two-dimensional echocardiography and the pressure half-time method, and the results for all three noninvasive methods were compared with those obtained at cardiac catheterization. By Doppler color flow imaging, mitral valve area could be determined in all patients and there was a significant correlation between the Doppler jet and catheterization estimates of mitral valve area (r = 0.93). Valve area determined by two-dimensional echocardiography correlated well with catheterization measurements in 26 patients (r = 0.84). However, the area could not be determined in 4 (13%) of the 30 patients because of technical problems. Although there was a fair correlation between the valve area determined by the pressure half-time method and catheterization (r = 0.79), this method tended to overestimate valve area in patients with aortic regurgitation.

Cathet Cardiovasc Diagn. 1991 Jul;23(3):211-8.

Interpretation of cardiac pathophysiology from pressure waveform analysis: the left-sided V wave.

Kern MJ, Deligonul U.

Cardiology Division, St. Louis University Hospital, Missouri 63110.

The left-sided V wave is dependent on both left atrial and ventricular pressure/volume filling relationship. The cardiac rhythm and timing of atrial systole also influences the V wave. The morphology of the V wave can reflect the severity of mitral regurgitation with stenosis, but valve areas in this setting may be better assessed by a pressure half-time method. Finally, as queried in our first patient example, V wave alternans is a reflection of left ventricular pressure alternans in a failing heart. Other signs of poor left ventricular function in Figure 1 also included an elevated minimal diastolic pressure and markedly elevated left ventricular end diastolic pressure.

Int J Cardiol. 1991 Sep;32(3):389-94.

Assessment of mitral valvar stenosis by echocardiography: utility of various methods before and after mitral valvotomy.

Nair M, Arora R, Mohan JC, Kalra GS, Sethi KK, Nigam M, Khalilullah M.

Department of Cardiology, G.B. Pant Hospital, New Delhi, India.

Cross-sectional and Doppler echocardiography are currently the most important non-invasive tests for the evaluation of mitral stenosis. Recent experience has, however, shown that parameters that are reliable before mitral valvotomy may not be valid after the procedure. We have studied the validity of estimation of the area of the mitral valve by echo-planimetry, by Doppler pressure half time and the transmitral end-diastolic pressure gradient calculated by continuous wave Doppler in 100 patients (aged 10- 30 years) before and after balloon mitral valvoplasty (n = 70) or surgical closed mitral valvotomy (n = 30). These patients underwent cardiac catheterisation and echocardiographic studies before, immediately after and 8-12 (9.3 +/- 2.2) weeks following ba lloon valvoplasty or closed valvotomy. The area as estimated echocardiographically correlated well with that obtained by the Gorlin formula before (r = 0.80), but not immediately after (r = 0.67) or on follow up after mitral valvotomy. There was good corr elation between Doppler pressure half time and the area as estimated by the Gorlin formula before (r = 0.89) and on follow up after valvotomy (r = 0.82), but the correlation was not as good in the immediate period after valvotomy (r = 0.60). The end-diast olic pressure gradients obtained by Doppler examination and at cardiac catheterisation correlated well with each other before (r = 0.94), immediately after valvotomy (r = 0.92) and on follow up (r = 0.94). Hence, the reliability of estimation of the area of the mitral valve by echo-planimetry and by Doppler pressure half time varies according to the time at which the examination is performed following commissurotomy.

Am J Cardiol. 1991 Dec 1;68(15):1485-90.

Doppler echocardiographic estimation of mitral valve area during changing hemodynamic conditions.

Braverman AC, Thomas JD, Lee RT.

Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115.

Patients with mitral stenosis often present during periods of hemodynamic stress such as pregnancy or infections. The Doppler pressure half-time method of mitral valve area (MVA) determination is dependent on the net atrioventricular compliance as well as the peak transmitral gradient. The continuity equation method of MVA determination is based on conservation of mass and may be less sensitive to changes in the hemodynamic state. To test this hypothesis, 17 patients admitted for catheterization with symptomatic mitral stenosis and no more than mild regurgitation underwent Doppler echocardiography at rest and during supine bicycle exercise targeted to an increase in heart rate by 20 to 30 beats/minute. Net atrioventricular compliance was also estimated noninvasively. Cardiac output and transmitral gradient increased significantly during exercise (p less than 0.001), while net atrioventricular compliance decreased (p less than 0.001). MVA by the pressure half-time method increased significantly during exercise from 1.0 +/- 0.2 to 1.4 +/- 0.4 cm2 (p less than 0.001). There was no significant difference in MVA estimation using the continuity equation comparing rest to exercise, with the mean area remaining constant at 0.8 +/- 0.3 cm2 (p = 0.83). Thus, during conditions of changing hemodynamics, the continuity equation method for estimating MVA may be preferable to the pressure half-time method.

Klin Wochenschr. 1991 Dec 11;69(20):924-9.

Value of a modified continuity equation method to quantify mitral valve area in patients with mitral stenosis and sinus rhythm.

Voelker W, Regele B, Dittmann H, Schmid M, Mauser M, Kuhlkamp V, Karsch KR.

Abteilung III der Medizinischen Universitatsklinik Tubingen.

To quantify valve area in mitral stenosis, a modified continuity equation method using continuous wave Doppler and thermodilution measurements was applied. In 14 patients with mitral stenosis and sinus rhythm (age: 49 +/- 11 years), transmitral flow velocity was recorded by continuous wave Doppler during right and left heart catheterization. Mitral valve area was calculated by three different methods: 1. According to the continuity equation, stroke volume (thermodilution technique) was divided by the registered time velocity integral of the mitral stenotic jet (continuous wave Doppler). 2. Mitral valve area was calculated by the pressure half-time method. 3. Simultaneous pulmonary capillary wedge and left ventricular pressure measurements were used for determination of mitral valve area according to the Gorlin formula. The mitral valve area determined by application of the continuity equation (y) showed a close correlation to the valve area calculated by the Gorlin equation (x): y = 0.73x + 0.12, SEE = 0.11 cm2, r = 0.88, P less than 0.001. In contrast, the correlation between mitral valve area determined by pressure half-time (y) and the Gorlin formula (x) was not as good: y = 0.77x + 0.11, SEE = 0.26 cm2, r = 0.65, P less than 0.05. Thus, the continuity equation method using combined continuous wave Doppler and thermodilution technique allows a valid determination of mitral valve area. In patients with mitral stenosis and sinus rhythm, this technique is superior to the noninvasive determination of mitral valve area by the conventional pressure half-time method.

J Cardiol. 1992;22(1):159-69.

A simple noninvasive measurement of stenotic mitral valve area: an alternative approach using M-mode and Doppler echocardiography.

Tei C, Shah PM, Bae JH, Toyama Y, Horikiri Y, Choue CW, Choi CJ, Tanaka N.

Department of Rehabilitation and Physical Medicine, Kagoshima University School of Medicine.

Doppler echocardiography is a widely used noninvasive technique to examine the mitral valve area (MVA) by obtaining mitral pressure half-time (PHT) and to assess the severity of the stenosis. However, several hemodynamic factors influence the PHT and may render the PHT data inaccurate in any measurement of MVA under certain conditions. Using a simple echo-Doppler (E-D) method, we assessed the MVA in a physiological equation. The mitral flow volume (MFV) is represented by MVA x transmitral mean flow velocity (mV) x diastolic filling time (DFT). Thus, the formula can be restated as MVA (cm2) = MFV (cm3)/mV (cm/sec) x DFT (sec). We measured MFV by M-mode, and mV and DFT by continuous wave Doppler echocardiography. This formula was tested in 43 patients with isolated mitral stenosis. MVA was obtained by the PHT and E-D methods, and the data obtained were validated against the results of cardiac catheterization. The results obtained using the E-D method showed much better correlation (r = 0.82) with those of catheterization than those with the PHT method (r = 0.52). The inter- and intraobserver variabilities were checked. The results obtained with the E-D method were found to be reproducible. To further validate the accuracy of the E-D method, MVA was measured by both methods at different R-R intervals after exercise and the results were compared. The MVA obtained by the PHT method showed marked variations; whereas, that obtained by the E-D method remained nearly constant. Similarly, in a patient with atrial fibrillation, the MVA assessed by the PHT method varied from beat to beat; whereas, the fluctuations in MVA were minimal using the E-D method. We concluded that the E-D method can be reliable and clinically easily applicable for the accurate assessment of MVA.

Eur Heart J. 1992 Feb;13(2):152-9.

Effect of heart rate on transmitral flow velocity profile and Doppler measurements of mitral valve area in patients with mitral stenosis.

Voelker W, Regele B, Dittmann H, Mauser M, Ickrath O, Schmid KM, Karsch KR.

Department of Cardiology, Tuebingen University, Germany.

To study the effect of heart rate changes on Doppler measurements of mitral valve area atrial pacing was performed in 14 patients with mitral stenosis and sinus rhythm. Continuous wave Doppler and haemodynamic measurements were performed simultaneously at rest and during pacing-induced tachycardia. (1) Mitral valve area was determined using the conventional pressure half time method. 2) Additionally, mitral valve area was calculated with a combined Doppler and thermodilution technique according to the continuity equation. (3) Simultaneous invasive measurements were used for calculation of the mitral valve area according to the Gorlin formula. With increasing heart rate (69 +/- 13-97 +/- 15-114 +/- 13 beats min-1) mitral valve area either determined by the continuity equation (1.0 +/- 0.2-1.0 +/- 0.3-1.1 +/- 0.4 cm2) or the Gorlin formula (1.2 +/- 0.3-1.2 +/- 0.4-1.3 +/- 0.4 cm2) remained constant. Both methods correlated closely not only at rest (r = 0.88, SEE = 0.11 cm2, P less than 0.001), but also during atrial pacing (first level: r = 0.95, SEE = 0.10 cm2, P less than 0.001, second level: r = 0.95, SEE = 0.13 cm2, P less than 0.001). In contrast, mitral valve area calculated according to the pressure half time method increased significantly during atrial pacing (1.0 +/- 0.3-1.8 +/- 0.5-2.0 +/- 0.5 cm2).

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