THERAPY AND PREVENTION VALVULAR HEART DISEASE Mechanisms of increase in mitral valve area and influence of anatomic features in double-balloon, catheter balloon valvuloplasty in adults with rheumatic mitral stenosis: a Doppler and twodimensional echocardiographic study CHERYL L. REID, M.D., CHARLES R. MCKAY, M.D., P. A. N. CHANDRARATNA, M.D., DAVID T. KAWANISHI, M.D., AND SHAHBUDIN H. RAHIMTOOLA, M.B., F.R.C.P. Downloaded from http://circ.ahajournals.org/ by guest on June 18, 2017 ABSTRACT To study the mechanism of increase in the mitral valve area (MVA) and the anatomic features of the mitral valve that may affect the results of catheter double-balloon valvuloplasty (CBV) in adult patients with mitral stenosis, Doppler and two-dimensional echocardiography was performed in 12 patients before and immediately after CBV. Immediately after CBV, there was an increase in the transverse diameter of the mitral valve orifice from 18 + 1.6 to 25 + 2.8 mm (mean -+ SD, p 20 degrees (p < .05) < .001). The anterior angles at the commissure increased from 33 ± 6 to 57 and the posterior angles from 36 9 to 54 + 14 degrees (p < .05). The MVA was greater after CBV in patients with pliable mitral valves (2.6 0.7 cm2) compared with those with rigid mitral valves (1.9 ± 0.8 cm2; p = .08). After CBV, MVA was smaller in patients with calcification (2.1 ± 0.2 cm2) compared with those without (2.7 0.5 cm2; p - 10) and in those with subvalvular disease (2.0 ± 0.6 cm2) compared with those without (2.9 ± 0.9 cm2; p = .03). The MVA by Doppler ultrasound before CBV (1.0 0.2 cm2) correlated well with MVA by cardiac catheterization (1.0 ± 0.3 cm2; r = .8, SEE = 0.2 cm2). After CBV, the correlation of MVA by Doppler ultrasound (2.0 + 0.5 cm2) with MVA by cardiac catheterization (2.4 0.8 cm2) was poor (r .3, SEE 0.44 cm2). Doppler studies showed that new mitral regurgitation was produced in four patients (mild in three and moderate in one) and an increase of mitral regurgitation was produced in one patient. We conclude that (1) the increase in MVA by double-balloon CBV occurred along the natural planes of the commissures resulting in increased commissural angle opening; (2) severe calcification of the commissures with rigid valve leaflets was associated with the least increase in mitral valve area after CBV; calcification of the commissures, rigid valve leaflets, and subvalvular disease were associated with smaller increases in MVA, (3) new or an increase in mitral regurgitation occurred in over a third of the patients by Doppler, but in most patients the change was small, and (4) Doppler ultrasound provided a reasonable estimate of MVA before CBV but was of limited value in the estimation of the MVA immediately after CBV. Circulation 76, No. 3, 628-636, 1987. ± ± ± . ± ± CLOSED OR OPEN mitral commissurotomy and valve replacement have been the preferred methods of treatment for most patients with severe rheumatic mitral stenosis. 1-5 Recently, catheter balloon valvuloplasty (CBV) with percutaneous single-balloon cathFrom the Section of Cardiology, Department of Medicine, LAC-USC Medical Center. University of Southern California School of Medicine, Los Angeles. Address for correspondence: Cheryl L. Reid, M.D., LAC-USC Medical Center, Section of Cardiology, 2025 Zonal Ave., Los Angeles. CA 90033. Received Jan. 12, 1987; revision accepted June 11, 1987. Presented in part at the Annual Scientific Sessions of the American College of Cardiology. New Orleans, March 1987. 628 = = eters has been performed in patients with rheumatic mitral stenosis .6-I CBV with a double-balloon technique has been shown to be more effective in dilatation of stenotic rheumatic mitral valves in adult patients.'2 13 The purposes of this study were to determine by two-dimensional and Doppler echocardiography (1) the mechanism by which the mitral valve area (MVA) is increased, (2) whether anatomic features of the mitral valve and subvalvular apparatus influence the results of CBV, (3) whether mitral regurgitation is produced or increased, and (4) whether the Doppler technique can accurately estimate change of MVA immediately after CBV. CIRCULATION THERAPY AND PREVENTION-VALVULAR HEART DISEASE FIGURE 1. Method of measurement of the morphologic changes induced by double-balloon CBV illustrated in the twodimensional echocardiographic parasternal short-axis view. A, The transverse diameter (TD) is measured between the anterior (A) and posterior (P) commissures during the maximal opening of the mitral valve orifice (MVO) in early diastole. B, The angle of the commissural opening is measured between two tangential lines drawn from the point of each commissure to the anterior and posterior leaflets of the mitral valve. Methods Downloaded from http://circ.ahajournals.org/ by guest on June 18, 2017 Patients. The study consisted of the first 12 patients with symptomatic mitral stenosis who underwent CBV by the doubleballoon technique. Informed consent was obtained from all patients. There were 11 women and one man who ranged in age from 25 to 70 years (mean 43 ± 15). Two patients were in NYHA functional class 1I, eight in class Ill, and two in class IV. Three patients had undergone a previous mitral commissurotomy. Three patients were in atrial fibrillation. Patients with echocardiographic evidence of left atrial thrombus were considered not suitable for CBV. Initially patients with pulmonary edema, high pulmonary artery pressures near systemic arterial pressure and low cardiac output, and right heart failure were also excluded. Patients with evidence of other severe valve disease requiring surgery or mild mitral stenosis by cardiac catheterization were excluded. Two-dimensional echocardiography. All patients had a two-dimensional (2D) echocardiogram on the day before cardiac catheterization. After CBV, 2D echocardiographic studies were performed the day after the procedure in 1 1 patients and at 1 month after CBV in one patient. One patient did not have an initial study because of equipment malfunction and was excluded from analysis. In two patients, the mitral valve was A heavily calcified and the orifice could not be visualized for measurement of morphologic changes. These patients were included for analysis of anatomic features only. An Irex Meridian Echocardiographic Doppler System was used to record the images on videotape for playback analysis. The smallest orifice of the mitral valve was located in the parasternal short-axis view by scanning from the level of the left atrium to the left ventricle. The gain settings were adjusted to obtain the maximum visualization of the entire circumference of the mitral valve orifice. Assessment ofmorphologic changes. The transverse diameter of the mitral valve orifice during maximal valve opening in early diastole was measured between the anterior and posterior commissures. The opening angle at the two commissures was assessed by drawing a tangential line from the point of the commissure to the maximal opening of the anterior and posterior leaflet of the mitral valve (figures 1 and 2). A mean of three measurements was used in patients in sinus rhythm and five to 10 measurements in patients with atrial fibrillation. Since there is no standard for evaluating changes in transverse diameter or commissural angle after CBV, the changes were assessed by the extent to which these variables approached normal values. Therefore, 2D echocardiograms of 10 normal men and 10 normal women were analyzed. These 20 patients B FIGURE 2. Two-dimensional echocardiogram in the parasternal short-axis view at the level of the mitral valve during early diastole in patient 2. A. Before double-balloon CB V the transverse diameter was 20 mm and the angles of the anterior and posterior commissure were 30 and 32 degrees, respectively. Calcification of the posterior commissure was present. B, After CBV the transverse diameter increased to 27 mm and the opening angles increased 93% and 13% for the anterior and posterior commissure, respectively. The increase in transverse diameter associated with an increase of the anterior angle of opening suggests that the split occurred to a greater extent at the anterior commissure. Vol 76, No. 3, September 1987 629 REID et al. were selected on the basis of a negative history of cardiac disease Downloaded from http://circ.ahajournals.org/ by guest on June 18, 2017 and normal cardiac examination (15 patients) or a diagnostic cardiac catheterization and angiography that did not show any mitral valve abnormality (five patients). Patients with any evidence of valvular, myocardial, coronary artery, or any other cardiac disease were excluded from the normal group. Anatomic features of the mitral valve and subvalvular apparatus before CBV. The severity of calcification at each commissure was assessed as mild, moderate, or severe. The mitral valve was judged pliable if the body of the leaflets was free of calcium and had a wide excursion during diastole. Subvalvular involvement was evaluated by noting the presence of calcification and thickening when compared with the surrounding endocardium. Measurements of MVA. The MVA was obtained from a freeze-frame analysis of the maximal mitral valve opening in early diastole. The mitral valve orifice was planimetered directly from the video screen with a light-pen system; the area in square centimeters was assumed to be the effective MVA. Measurements were made in all patients both before and after CBV. A mean of three measurements was obtained in patients in sinus rhythm and five to 10 measurements in patients with atrial fibrillation. Doppler ultrasound MVA. Doppler echocardiograms were obtained successfully in all 12 patients. Recordings were made with an Irex Meridian Echocardiographic Doppler System with the use of both imaging and nonimaging transducers at a frequency of 2.0 MHz. Continuous-wave Doppler ultrasound recordings were made from the apical four-chamber view while the transducer was angled with the use of visual and auditory monitoring to obtain the maximal velocity across the mitral valve. No correction was made for the angle between the Doppler signal and transmitral blood flow. A hardcopy recording was made at 75 mm/sec, and the MVA was calculated from the Doppler recordings by the pressure half-time method. 14 A mean of three measurements was obtained for patients in sinus rhythm and a mean of five to 10 measurements for patients in atrial fibrillation. Pre-CBV studies were obtained on the day before CBV in seven patients. PostCBV recordings were made at 1 day in four patients and l week in one patient. Simultaneous Doppler recordings and hemodynamic measurements were made during cardiac catheterization before CBV in five patients and simultaneously after CBV in seven patients. Assessment of mitral regurgitation. The presence and severity of mitral regurgitation was assessed by pulsed Doppler examination. The severity of the mitral regurgitation was graded from 0 to 4 + based on the extent to which the regurgitant jet could be recorded within the left atrium.'5 In addition, regurgitation detected only immediately above the value leaflets was graded as trace mitral regurgitation to distinguish it from more significant 1 + mitral regurgitation. The Doppler ultrasound assessment of mitral regurgitation was made 1 day before CBV in all patients. After CBV, assessment of the mitral regurgitation was made at 1 day in 1 1 patients and at 1 week in one patient. Cardiac catheterization and CBV. All patients had complete diagnostic right and left heart catheterization and angiography before CBV. At CBV, right and left heart pressures, blood oxygen saturations, cardiac output, and left atrial and left ventricular angiograms were obtained both before and after CBV. Mitral valve area was calculated by standard formulas16 from the simultaneous left atrial and left ventricular pressures recorded at 15 cm/sec paper speed and the thermodilution cardiac output. No correction was made for the presence of mitral regurgitation in the calculation of the MVA. The double-balloon technique of CBV for mitral stenosis has been previously described. 12 13 Briefly, the technique consists 630 of two separate transseptal catheters placed across the interatrial septum. The mitral valve dilatation catheters were then inserted over exchange guidewires and positioned side by side across the stenotic mitral valve. The balloons were then inflated simultaneously while aortic pressure and pulmonary arterial wedge pressures were monitored continuously. After CBV, the patient was monitored overnight in the intensive cardiac care unit. The patient was ambulatory the next day and was discharged from the hospital 2 days after the procedure. Data analysis. 2D and Doppler echocardiographic recordings were analyzed by an experienced echocardiographer who was blinded to the results of the cardiac catheterization. A second echocardiographer evaluated the anatomic features of the mitral valve and subvalvular apparatus before CBV and was blinded to both the results of the cardiac catheterization and measurement of the morphologic changes. The relationship between Doppler and 2D echocardiographic and cardiac catheterization estimates of the MVA were compared by linear regression analysis. A paired t test was used to compare the pre- and post-CBV measurement of the transverse diameter and the angles at the commissures of the mitral valve orifice. Data are expressed as mean + SD. Results Hemodynamic results. Immediate reductions in the severity of the mitral stenosis were achieved in all 12 patients (table 1). There was an increase in mean MVA from 1.0 ± 0.3 cm2 before CBV to 2.4 + 0.8 cm2 after CBV (p < .001). Mitral regurgitation by angiography before CBV was graded as absent in four patients, 1 + in seven patients, and 2 + in one patient. After CBV, repeat left ventricular angiography showed no new mitral regurgitation or increase in the severity of preexisting mitral regurgitation in any patient. Two-dimensional echocardiography. Measurements of mitral valve orifice in normal subjects. In the group of normal subjects the mean transverse diameter of the mitral valve orifice was 26 ± 2.3 mm (range 24 to 30) for women and 29 ± 2.6 mm (range 26 to 34) for men (p = .03, figure 3). The angle of anterior commissural opening was 90 + 7 degrees (range 83 to 100) for men and 91 ± 6 degrees (range 79 to 97) for women (p - NS); the angle at the posterior commissural opening was 93 ± 3 degrees (range 86 to 96) for men and 92 ± 6 degrees (range 84 to 101) for women (p = NS, figure 3). Morphologic changes after CBV. Tears of the valve leaflets or rupture of the chordae of the mitral valve were not visualized in any patient. The mean transverse diameter of the mitral valve orifice increased from 18 ± 1.6 mm before CBV to 25 ± 2.8 mm after CBV (p < .001) (figure 3). The mean increase for the group was 38 ± 17% (table 2). All patients in whom 2D echocardiograms could be obtained were women; there was no significant difference (p = .3) between the measurement of the transverse diameter after CBV in CIRCULATION THERAPY AND PREVENTION-VALVULAR HEART DISEASE TABLE 1 figure 3). The mean increase at the anterior commissure Cardiac catheterization, Doppler, and two-dimensional echocardiographic results in 12 patients undergoing mitral valve CBV was 71 +- 48% and that at the posterior commissure was 47 ± 23%. The angle of commissural opening after Patient Pre-CBV Post-CBV 2. Pre-CBV Post-CBV 3. Cardiac cath. HR MVA MR 80 0.6 0 Doppler HR MVA MR 80 0.5 2DE MVA In two patients (Nos. 8 and 9), heavy calcification precluded visualization of the mitral valve 77 1.3 1+ 79 2.2 1 + 89 1.1 70 1.6 Tr Tr 1.1 2.0 75 1.3 1+ - orifice for measurements. In these patients, the calcification was severe in one commissure and was associated with mild calcification of the subvalvular apparatus and rigid valve leaflets; these patients had the smallest MVAs after CBV, 1. 1 and 1.7 cm2. In three patients (Nos. 1, 2, and 4), there was mild calcification of one of the commissures with or without associated subvalvular disease; in two of these patients, the calcification was associated with failure to increase the respective angle of commissural opening (patients 2 and 4). Calcification of both commissures present in two patients (Nos. 5 and 12) was associated with only a small 3 mm increase in the transverse diameter. The presence of calcification resulted in a mean MVAof21 ± 02cm2comparedwith2.7 ± 0.5cm2 106 3.6 1+ 104 2.4 1+ 4 84 1.1 0 93 2.2 0 81 0.9 1 + 100 1.7 1 + 0.9 1.6 Pre-CBV 108 1.1 1+ 58 0.9 1+ 0.9 Post-CBV 108 2.9 80 1+ 1.7 78 0.8 1 + 72 2.9 1 + 63 0.9 1 + 81 2.4 1 + 1.2 2.2 96 0.8 1+ 96 1.9 1+ 74 0.9 0 98 2.4 1+ 0.9 2.3 71 0.6 1+ 98 1.1 1 + 73 1.0 1 + 98 1.6 1 + Downloaded from http://circ.ahajournals.org/ by guest on June 18, 2017 1+ 1.5 6. Pre-CBV Post-CBV 7. Pre-CBV Post-CBV Pre-CBV Post-CBV 9. Pre-CBV Post-CBV subvalvular appa- 0.8 2.0 102 1.6 1+ 5. Anatomic features of the mitral valve and 0 67 1.7 01 Post-CBV Pre-CBV this group of patients was significantly smaller (p < .001) than the corresponding values in normal women. 90 2.9 0 Pre-CBV Post-CBV CBV at both the anterior and posterior commissures in ratus (table 3). -(p = .10) in patients without calcification. Those patients with pliable leaflets had a greater mean MVA after CBV (2.6 + 0.7 cm2) compared with those with 66 0.6 2+ 69 0.7 Tr rigid mitral valves (1.9 ± 0.8 cm2; p = .08). The 74 1.7 2+ 77 1.6 1+ presence of subvalvular disease was also associated with a smaller MVA after CBV (mean 2.0 ± 0.6 cm2) 7 1.1 00. 77 1.1 0 Pre-CBV 74 1.3 Post-CBV 97 3.6 0 101 2.7 2 + 3.0 than in patients without subvalvular disease (mean 2.9 ii. ±0.9 cm2; p = .03) (figure 4). Pre-CBV 96 1.0 1+ 96 1.2 1+ 1.3 MVA. The 2D echocardiographic estimates of the Post-CBV 105 2.1 1 + 118 2.7 1 + 2.1 MVA in the nine patients in whom it could be measured 73 1.1 0 79 12 0 13 12. was 1.1 ± 0.2 cm2 before CBV (range 0.8 to 1.3 cm2) Post-CBV 731 20 0 77 2.5 Tr and 2.2 ± 0.4 cm2 after CBV (range 1.6 to 3.0 cm2). 2.5 Mean pre-CBV 86 1.0 76 1.0 The correlation of 2D echocardiographic estimates of 1.0 +SD 14 0.3 10 0.2 0.2 MVA before and after CBV with those obtained by Mean post-CBV 92 2.4 89 2.0 cardiac catheterization was poor (r = .4 and r .4). 2.2 +SD 12 0.8 16 0.5 0.4 Throughout the entire range of MVAs observed, i.e., HR = heart rate (beats/min); MR = mitral regurgitation (0 to 4 +); both before and after CBV, the correlation was good MVA = mitral valve area (cm2); Tr trace; 2DE = two-dimensional echocardiography. this group of patients (25 ± 2.8 mm) and normal women (26 ± 2.3 mm). In all patients the angle of commissural opening increased at one or both commissures. The anterior commissure increased from 33 + 6 degrees before CBV to 57 ± 20 degrees after CBV (p < .05) and the posterior commissure increased from 36 ± 9 degrees before CBV to 54 + 14 degrees after CBV (p < .05, Vol. 76, No. 3, September 1987 (r = .8, SEE = 0.3 cm 2). Doppler ultrasound (table 1) MVA. The MVA calculated from the Doppler velocity recordings before CBV in all 12 patients was 1.0 ± 0.2 cm2 (range 0.5 to 1.3 cm2). After CBV the mean MVA increased significantly to 2.0 ± 0.5 cm2 (p < .001); range 1.5 to 2.6 cm2. The correlation of the Doppler ultrasound estimates of the MVA with that obtained by cardiac catheterization before CBV was r = .8 (SEE 0.2 cm2, figure 5). After CBV the correlation between the two techniques was poor (r = .3, SEE = 0.44 631 REID et al. p <. 00i p = NS A. B. p <.001 p <.001 C. p<.OOl p <.001 r- 32 96; T o L Q'84- -! c] ac. // m a NS p= NS 84 T 1 24 4 1 T ii W -1t 28 E 96h iT (D Icolic p=NS 72j z U w 4 p<.O t _ p = .03 20 T z / 60a: 0 16 (D LilD U) a: > ' CL z 481 W cr z 12 361 0 z 0 12[ o8i 24 U I _ _ IL p ,meon -SD p <.05 c.05 4 Prre Male Female Past Downloaded from http://circ.ahajournals.org/ by guest on June 18, 2017 CB 3V NORMALS I I ! Male Female CBV MITRAL STENOSIS NORMALS Pre Male Female Past CBV CBV MITRAL STENOSIS NORMALS Pre Post CBV CBV MITRAL STENOSIS FIGURE 3. Comparison of transverse diameter and angles of commissural opening before and after CBV in nine patients with mitral stenosis with 10 normal women and 1 0 normal men. A, The mean transverse diameter was significantly different between normal women and normal men (p = .03). Before CBV, the transverse diameter was significantly smaller in the patients compared with the normal women. After CBV there was no significant difference between the patients and normal women. Although the anterior angle (B) and posterior angle (C) of commissural opening increased after CBV, both were significantly smaller than those of normal women. cm2). The correlation of all MVAs (before and after CBV) by Doppler with those obtained by cardiac catheterization was good (r = .8, SEE = 0.4 cm2, figure 5). Mitral regurgitation (figure 6). Before CBV, no mitral regurgitation was detected in four patients, trace mitral regurgitation was found in two patients, and 1 + mitral regurgitation in six patients. Doppler ultrasound failed to identify the presence of mitral regurgitation dem- onstrated by angiography in one patient before CBV. After CBV, Doppler ultrasound detected no change in the presence or severity of mitral regurgitation in seven patients. The presence and severity of the mitral regurgitation by Doppler ultrasound increased from absent to trace in one patient, absent to 1 + mitral regurgitation in two patients, and trace to 1 + mitral TABLE 2 Morphologic changes in mitral valve orifice by CBV Angle of commissure (degrees) Transverse diameter (mm) Patient Pre Post 1 20 20 17 19 18 15 17 19 18 18 1.6 28 27 24 22 26 23 29 24 2 4 5 6 7 10 11 12 Mean +SD 21 25A 2.8 Change (%) + 40 + 35 +41 + 16 + 44 + 53 +71 + 26 + 17 + 38 + 17 Anterior Posterior Change Pre Post 28 30 27 25 33 42 39 36 37 33 6 54 58 29 43 42 63 51 74 97 57B 20 (%) Pre Post + 93 + 93 31 32 26 26 46 44 48 27 40 36 53 36 47 44 60 57 64 39 82 54B 14 +7 + 72 + 27 + 50 +31 + 106 + 162 + 71 +48 9 Change (%) + 71 + 13 +81 + 69 + 30 + 30 +33 + 44 +51 + 47 +23 Ap <.001 post- vs pre-CBV; Bp <.05 post- vs pre-CBV. 632 CIRCULATION THERAPY AND PREVENTION-VALVULAR HEART DISEASE TABLE 3 Anatomic features of the mitral valve and subvalvular apparatus before CBV Commissures Patient Anterior I 2 4 5 6 7 8 9 10 11 12 Mild Ca+ + Mild Ca+ + Mild Ca+ + - Severe Ca + Posterior Subvalvular apparatus Pliable Mild Ca+ + Mild Ca+ + Severe Ca+ + Mild Ca++ Valve leaflet mobility Mild Ca+ + Pliable Pliable Rigid Pliable Pliable Rigid Rigid Pliable Pliable Rigid Thickened Mild Ca+ + Thickened Mild Ca + Mild Ca ++ Thickened Thickened Downloaded from http://circ.ahajournals.org/ by guest on June 18, 2017 Ca + + = calcification. regurgitation in one patient; in one patient new 2+ mitral regurgitation was detected. Discussion The technique of CBV in patients with mitral stenosis was first described by Inoue et al.6 using a single balloon and by Al Zaibag et al.12 using the doubleballoon technique. Initial results with the new doubleballoon technique appear encouraging.12' 13 Inoue et al. showed, that the mechanism by which the singleballoon technique works is splitting of commissures. The mechanism by which double-balloon CBV produces the increase in mitral valve area has not been reported. After CBV, the increase in MVA may result from (1) splitting of the commissures, (2) stretching of the valve leaflets and subvalvular apparatus, and/or (3) tears or fractures of the valve leaflets. The latter has been described in patients undergoing CBV for aortic N 4- E CALCIFICATION VALVE MOBILITY SUBVALVULAR DI SEASE 1 O3.c m._ 'U I-2 2 O- U t0 Absent Present Plioble Rigid Absent Present FIGURE 4. The anatomic features of the mitral valve in relationship to the resultant mean MVA immediately after CBV are shown for the presence or absence of calcification, subvalvular disease, and pliable or rigid mitral valves in 11 patients. The mean MVA was greater in these groups with pliable mitral valves without calcification or subvalvular disease. Vol. 76, No. 3, September 1987 stenosis.'7 Each of these potential mechanisms has different applications for immediate results and longterm success of the procedure. Pathologic studies have shown that rheumatic mitral stenosis results from (1) fusion and shortening of the chordae, (2) rigidity and thickening of the valve leaflets, (3) fusion of the commissures, and (4) combinations of these abnormalities.'8-20 The commissural fusion, however, is the most important component in 76% of the cases.18 Results with surgical, open or closed, mitral commissurotomy indicate that excellent long-term results will occur if the commissures are appropriately incised2' 5, 21, 22 but that the results are less satisfactory in the presence of rigid and calcified valves.23 Inoue performed single-balloon CBV of the mitral valve in the operating room during open mitral commissurotomy in six patients and found that at least one commissure was adequately separated in all patients.6 The results of our study show that the increase in MVA occurring after double-balloon CBV is also caused by a split along the natural planes of one or both commissures. Before CBV the mean transverse diameter in our patients was 18 ± 1.6 mm; it is of interest that this finding is similar to the intercommissural diameter of 19 mm measured at autopsy in patients with mitral stenosis. 18 Moreover, the values of the transverse diameter after CBV corresponded to autopsy measurements in normal subjects.24 After CBV there was no significant difference in the transverse diameter measurement in our patients (25 ± 2.8 mm) and those we measured in normal women (26 + 2.3 mm); all but one of our patients were women. One would expect, however, that post-CBV transverse diameters might be larger in men. If stretching of the mitral valve leaflets or subvalvular apparatus rather than commissural splitting was the major mechanism by which the MVA increased after CBV, then the increase in transverse diameter would be small and only the angles of commissural opening would be expected to increase. In two of our patients (Nos. 5 and 12), the increase in transverse diameter was modest, although both angles of commissural opening increased. Failure to increase the transverse diameter in these patients was associated with calcification of both commissures and may represent an inability to split the commissures because of the calcifications and a component of stretching; this finding is compatible with those seen at surgery.23 Longer follow-up of these patients will be required to determine whether this degree of increase in transverse diameter is sufficient to sustain good long-term results. Analysis of data from surgical mitral commissurot633 REID et al. lA~ PRE- CBV 4 - 4 POST-CBV j E E E 3 3 <r 0 0 0 E2 -/ 2 cl: ALL PRE- AND POST- CBV 4 2 2 2 08 cr 0 uJ 0L~1 rO- O y D * 0 C-J LLI .8 =.65x + .32 SEE - 0.15 1 2 3 CATH MVA (cm2) = 0 4 0 a- 0.3 y= .19x + 1.6 0 SEE = 0.44 0 1 2 3 CATH MVA (cm2) 4 - ,< ,~~r= y 0.8 =.54x + .56 SEE 0 0.4 2 3 1 CATH MVA (cm2) 4 FIGURE 5. Linear regression analysis of MVA measured by Doppler ultrasound compared with that measured by cardiac catheterization before (A) and after CBV (B). The Doppler-derived MVA before CBV showed a good correlation (r .8) with catheterization-derived MVA but after CBV the correlation was poor (r = .3). With all pre- and post-CBV values considered together (C), the correlation between Doppler and cardiac catheterization was good (r .8). = = omy has Downloaded from http://circ.ahajournals.org/ by guest on June 18, 2017 shown that 70% of patients will maintain good results after 5 years of follow-up if one commissure is successfully opened and 89% if both commissures are opened.25 The changes in the angles of opening at the commissures after CBV may also be used to assess splitting at the associated commissure. In all our patients, the opening angle between the commissures showed an increase in one or both angles. In two patients (Nos. 2 and 4) only one angle of commissural opening showed an increase. Since the transverse diameter increased, we interpret this increase to have resulted from a split only at the commissure with the increase in the angle of opening. Failure to increase an opening angle at a commissure or a change in opening of only a few degrees associated with an increase in transverse diameter in these patients was related to calcification at the unsplit commissures. An increase in transverse diameter accompanied by an increase of both angles at the commissures suggests that both commissures were split, and this occurred in patients without commissural calcium. Although the angles of commissural opening at both the anterior and posterior commissures showed a significant mean increase after CBV, they were still significantly less than the opening angles obtained in normal subjects. The presence of rigid mitral valve leaflets or subvalvular disease in addition to failure to split the commissure may also contribute to the failure of the angles of opening to approach normal values. Although the presence of rigid, calcified valves and subvalvular disease was associated with a smaller MVA after CBV than in those patients without these anatomic findings, it did not preclude a satisfactory result. One of the potential disadvantages of CBV is that the fusion of the chordae tendineae may not be relieved. However, chordal fusion as the dominant cause of mitral stenosis is present in only a minority of 634 patients (9%). 18 Our initial results show findings that are comparable to those obtained with open or closed mitral commissurotomy in which the subvalvular apparatus was assessed directly and fusion relieved.26 Al Zaibag et al. 12 noted splitting of the subvalvular mitral apparatus in one of two patients in whom they performed double-balloon CBV under direct vision during open mitral commissurotomy. Therefore, even when it is difficult to visualize the subvalvular apparatus directly by 2D echocardiography, the precise quantification of the morphologic changes produced by CBV in the manner we have described may provide evidence of the contribution of subvalvular disease to early and possibly late results. The production of significant mitral regurgitation after surgical commissurotomy is associated with a poor prognosis.525. 27, 28 Significant mitral regurgitation during open or closed mitral commissurotomy may be produced if a tear or incision is made into the anterior or posterior leaflet of the mitral valve or if the chordae tendineae are ruptured.'9' 29 Less severe degrees of mitral regurgitation may occur because the rigid valve leaflets and shortened chordae tendineae prevent complete closure of the leaflets after incision of the commissures or because of small tears in the valve leaflets. Although in our group of patients new or an increase in mitral regurgitation by Doppler ultrasound was detected in five patients after CBV, in only one patient was it considered to be moderate (2 + ). This differed from the findings by angiography in these patients. Angiography may fail to detect small amounts of mitral regurgitation and to distinguish qualitatively small changes in its severity, such as from trace to 1 + mitral regurgitation. Moreover, angiography may be interpreted as showing trace to 1 + regurgitation caused by an arrhythmia if the electrocardiogram is not simultaneously monitored; in our laboratory, the electrocarCIRCULATION THERAPY AND PREVENTION-VALVULAR HEART DISEASE CL Downloaded from http://circ.ahajournals.org/ by guest on June 18, 2017 Q) IT[ CL Tr[ 0 a Pre CBV Post CBV FIGURE 6. Assessment of the presence atid severity of mitral regurgitation by the pulsed Doppler technique in 12 patients before and after CBV. The 1 + grade of mitral regurgitation is subdivided into trace (Tr) and 1 + mitral regurgitation. Mild mitral regurgitation was produced in four patients and increased in one patient. In one patient, new 2 + mitral regurgitation occurred. diogram is photographed on the cineangiographic film and thus this problem is unlikely to occur. On the other hand, Doppler ultrasound may be overly sensitive and may detect trace to 1 + mitral regurgitation when there is none present.30 The regurgitation associated with mitral stenosis may occur in 'jets" and therefore may fail to be detected by Doppler ultrasound if a careful search of the left atrium is not made with the pulsed Doppler mode.31 This may be the reason why we failed to detect mitral regurgitation before CBV in one patient shown to have mitral regurgitation by angiography. In no patient did we detect the occurrence of a tear of the valve leaflets or rupture of the chordae tendineae; however, echocardiography may not be sensitive enough to detect small tears and ruptures. The significance of small increases in mitral regurgitation detected by Doppler ultrasound after CBV remains to be established. Vol. 76, No. 3, September 1987 Estimates of MVA by Doppler ultrasound have been shown to have a good correlation with results obtained by cardiac catheterization in patients with unoperated mitral stenosis (r = .85) as well as those who have undergone mitral commissurotomy (r = .90).32 The results of our study confirm that Doppler ultrasound shows a good correlation with cardiac catheterization for the MVA before CBV (r = .8, SEE = 0.15 cm2). After CBV, however, the results of the Doppler studies did not accurately reflect the changes in the MVA by cardiac catheterization (r = .3, SEE = 0.44 cm2), a finding not previously reported. The MVA by cardiac catheterization was not corrected for the presence of mitral regurgitation. However, if the mitral regurgitant flow had been considered, the calculated MVA would have been larger and thus the discrepancy between the mean MVA by cardiac catheterization (2.5 ± 0.8 cm2) and the mean MVA by Doppler (2.0 ± 0.5 cm2) would have been even greater. The poor correlation between the Doppler estimate of the MVA and that obtained by cardiac catheterization after CBV may be related to several factors such as small left-to-right shunts not detected by oximetry or to inherent problems with the Doppler pressure half-time method. The data in this series were inconclusive in this regard. At this time, caution should be exercised in using the Doppler estimate of the MVA to assess the results immediately after CBV. The results of this study show that the mechanism by which the MVA was increased after double-balloon CBV was a split along one or both commissures. By 2D echocardiography, this was seen as an increase in the transverse diameter between the commissures and was associated with an increased opening of the angle at one or both of the commissures. Severe calcification of the mitral valve with rigid valve leaflets was associated with the least increase in MVA. Calcification at both commissures was associated with an incomplete split of the commissures; calcification of a single commissure was associated with a failure to increase the angle of opening. These results suggest that better results with CBV might be expected in a patient with a pliable valve without evidence of commissural calcium or subvalvular disease, although the presence of one or more of these anatomic features does not preclude a satisfactory result. Although changes in the presence or severity of the mitral regurgitation was seen in five of the 12 patients by Doppler technique, in most patients the increase in mitral regurgitation was mild. 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Kwan OL, De Maria AN: Comparative accuracy of two-dimensional echocardiography and Doppler pressure half-time methods in assessing severity of mitral stenosis in patients with and without prior commissurotomy. Circulation 73: 100, 1986 CIRCULATION Mechanisms of increase in mitral valve area and influence of anatomic features in double-balloon, catheter balloon valvuloplasty in adults with rheumatic mitral stenosis: a Doppler and two-dimensional echocardiographic study. C L Reid, C R McKay, P A Chandraratna, D T Kawanishi and S H Rahimtoola Downloaded from http://circ.ahajournals.org/ by guest on June 18, 2017 Circulation. 1987;76:628-636 doi: 10.1161/01.CIR.76.3.628 Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231 Copyright © 1987 American Heart Association, Inc. All rights reserved. Print ISSN: 0009-7322. 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