Assessment of cardiac volumes and left ventricular mass by cine computed tomography before and after mitral balloon commissurotomy

Assessment of cardiac volumes and left ventricular mass by tine computed tomography before and after mitral balloon commissurotomy We used tine computed tomography (CT) to determine whether decreased mitral valve gradients and pulmonary artery pressures resulted in decreased right ventricular and atria1 volumes after percutaneous mitral balloon commissurotomy (MBC). In patients treated for severe mitral stenosis, previous studies have shown that after the mitral valve gradient decreases, the left atrial volume is reduced and left ventricular stroke volume is increased. The effects of commissurotomy on right heart chamber sizes have been difficuft to assess with angiography and echocardlography. Moreover, in follow-up studies performed after surgery, changes in cardiac chamber volumes occurring after the mitral valve gradient and pulreonary pressure are reduced are confounded by the effects of thoracotomy. Our group has previously demonstrated that tine CT can accurately measure both left and right cardiac chamber volwmes. We studied 11 female patients before, immediately after, and at 1 year after MBC, and 9 female control subjects of comparabfe age. To assess cardiac chamber volumes, we used tine CT. To assess the effects of MBC, we used cardiac catheterization and Doppler echocardiography. Compared to the control subjects, patients with mitral stenosis before MBC had larger total cardiac volumes (sum of all four chambers plus left ventricular myocardium) at ventricular end-diastole (381 + 50 ml for controls vs 529 & 102 ml for patients, p < 0.0005), larger left atrial (LA) end-diastolic volume and end-systolic volume (LA EDV: 72 -t 14 ml vs 186 + 59 ml, p < 09fJO5; LA ESV 31 + 8 ml vs 143 + 52 ml, p < O&005), and larger right atrfal (RA) ESV (28 f 6 vs 58 f 23 ml; p < 0.005). RA EDV tended to be larger (74 ? 18 ml vs 100 + 31 ml; p < 0.10). Right ventricular (RV) EDV were similar (111 + 23 ml vs 119 k 23 ml; difference not significant). During cardiac catheterization immediately after MBC, the mitral valve gradient decreased (11 + 3 mm Hg to 4 t 1 mm Hg, p < O.OOOl), mean pulmonary artery pressure decreased (29 + 9 mm Hg to 20 + 4 mm Hg; p < 0.025), and mitral valve area increased (1.1 t 0.3 cm2 to 2.8 + 1.2 cm2; p < 0.0005). These hemodynamic changes were confirmed by Doppler echocardiography. When tine CT studies obteined 5 rf: 6 days after MBC were compared to studies obtained before MBC, LA ESV was found to decrease significantly to 119 + 44 ml (p < 0.0005). RV EDV tended to increase (144 + 24 ml) and was significantly larger than in controls @ < 0.025). At 1 year after MBC, the mitral valve area was unchanged from soon after MBC as measured by Doppler echocardiography (2.1 + 0.5 cm2 vs 1.9 _t 0.5 cm?. Although the total cardiac volume was unchanged (552 f 132 ml), significant changes in the individual cardiac chamber volumes occurred. Compared to before MBC, LA volumes decreased further (LA EDV was 158 + 52 ml, p < 0.001; LA ESV was 102 t 39 ml, p < 0.0005) and RV EDV increased further to 148 rt 46 ml (p = 0.057). The LV EDV tended to increase compared with before MBC and compared with control subjects (119 + 34 ml; p < 0.10). The LV and RV end-systolic volumes and the RA end-systolic and end-diastolic volumes remained remarkably similar throughout. The LV mass increased (63 ? 11 vs 71 f 12 gm/m*; p < 0.005). Thus in patients wfth mitraf stenosis, the left and right atria are enlarged. After MBC, redistribution of cardiac chamber volumes occurs without a change in total cardiac volume. (AM HEART J 199+128:533-g.)

Maleah Grover-McKay, MD, Robert M. Weiss, MD, Byron F. Vandenberg, MD, Trudy L. Burns, PhD, Geoffrey J. Weidner, BS, Michael D. Winniford, MD, William Stanford, MD, and Charles R. McKay, MD Iowa City, Iowa

From Iowa.

the Departments

of Internal

Supported Affiliate.

in part

by grants

Received

for publication

July

from

Medicine

and

the American

22, 1993;

accepted

Radiology, Heart Dec.

University Association,

20, 1993.

of

Reprint requests: City, Iowa 52242.

Maleah

Grover-McKay,

Copyright ‘f’ 1994 0002~8703/94/$3.00

by Mosby-Year + 0 4/l/56176

MD,

Unwersity

of Iowa,

Iowa

Iowa Book,

Inc.

533

534

Grover-McKay

et al.

Mitral balloon commissurotomy (MBC) with the double-balloon technique is an effective treatment for symptomatic mitral stenosis in selected adult patients I-’ The effect of surgical mitral valve commissurotdmy on left atria1 (LA) and left ventricular (LV) cardiac chamber volumes has been previously described. After surgical mitral commissurotomy (or valve replacement), LV end-diastolic volume (EDV) increases. 7-10 However, during surgery the pericardium is opened and the configuration of the mitral apparatus may be altered. Both of these factors might affect subsequent measurements of LV volume and mass.11-13 In contrast, with MBC the pericardium remains intact and the chordal and papillary muscle relations are not usually altered. A recent study showed that at a mean of 11 months after MBC, LVEDV, LV end-systolic volume (ESV), and LV mass increased significantly as determined by echocardiography. l4 Effects of hemodynamic changes (i.e., aortic pressure and LV wall stress) on these measurements were not evaluated. Because right atria1 (RA) and right ventricular (RV) volumes are not reliably evaluated by echocardiography, the effect of MBC on all four cardiac chambers has not been reported. The volume of all four cardiac chambers and LV myocardium can be measured accurately with standard tine CT images (8 mm slice thickness).15-l7 In addition, left-to-right shunting can be detected by sequential imaging of a rapid injection of contrast material.18 We postulated that after MBC decreased pulmonary artery pressures in patients might result in decreased RV and RA volumes, hence in decreased total cardiac volume. Therefore the purpose of this study was to use tine CT to determine the effect of MBC on the volumes of all four cardiac chambers and on LV myocardial volume immediately and 1 year after MBC. METHODS Patient selection. Eleven women

who underwent successful MBC from February 1989 through November 1990 were included in the study. Criteria for patient selection for MBC have been described previously3, 5 and, in addition, included the absence of a pericardial effusion for this study. The MBC and follow-up protocols were approved by the Institutional Review Board, and all patients signed an informed consent. The mean age at the time of MBC was 48 & 11 years. Before and soon after MBC, seven patients were in sinus rhythm and four were in atrial fibrillation. One year after MBC, all patients except one were in sinus rhythm. Cine CT and echocardiographic studies were performed before, immediately after, and 1 year after MBC. For a comparison group, values for cardiac chamber volumes were obtained from normal tine CT studies in nine

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September 1994 Heart Journal

women (mean age 42 f 10 years) without clinical cardiovascular disease. The studies in these control subjects had been obtained

for clinical

indications.

Echocardiography. Two-dimensional

and Doppler echocardiography was performed 11 f. 13 days before MBC, 1.5 * 1.1 days after MBC and again 393 + 44 days after MBC. One patient did not have an echocardiogram 1 year after MBC. The echocardiograms were interpreted with previously described criteria6 by a single observer who was blinded to other data. Continuous and/or pulsed wave Doppler echocardiograms were performed with a HewlettPackard Sonos 500 or 1000 or an Advanced Technology Laboratory Ultramarkechocardiography instrument. Mitral valve inflow velocity was measured with the apical four-chamber view, and the mitral valve area was calculated with the pressure half-time method. The mitral valve mean gradient and valve area were calculated from the average of 2 to 3 beats.lg Mitral regurgitation was graded as none, mild, moderate, or severe on the basis of assessment in at least two planes with conventional color flow Doppler imaging.20 The presence of an interatrial shunt was assessed qualitatively with an intravenous saline solution contrast study and/or color flow imaging. LA dimensions were measured by M-mode or two-dimensional echocardiography.‘l, 22 Angiographic and hemodynamic evaluation. Mitral regurgitation was graded in the 10 patients with adequate ventriculograms as absent, mild, moderate, or severe.23 No patient had significant coronary artery disease. Intracardiac pressures were recorded before and after MBC before left ventriculography. The transmitral gradient was determined from simultaneous recording of LA and LV pressure. Cardiac outputs were measured by the Fick or thermodilution technique. Interatrial left-to-right shunting was assessed after MBC by oximetry. Significant left-toright shunting was defined as a pulmonary to systemic flow ratio of ~~1.5.~~ Mitral valve area was calculated by using the Gorlin formula.25 Cine computed tomography. Cine CT studies were performed with an Imatron (South San Francisco, Calif.) C-100 tine x-ray CT machine 5 f 6 days before, 8 f 19 days after, and 408 f 60 days after MBC. The technique has been described previously.15, w 26 In brief, the images were acquired in tine mode by triggering on the peak of the electrocardiographic R wave. Image acquisition began immediately after the R wave. An electron beam was magnetically deflected to sweep across four semicircular tungsten target rings. Two contiguous 8 mm thick tomographic images were produced per target ring with a 4 mm gap between images from adjacent target rings. At each of the eight levels, 10 images per cardiac cycle were obtained in 572 msec (i.e., each image was acquired in 50 msec with an 8 msec delay between each image). Before the images were obtained, an 18-gauge intravenous catheter was placed in an arm vein. The subjects were placed on the imaging couch and angled relative to the tungsten targets so that cardiac short-axis images could be obtained from apex to base. 27 To obtain short-axis images of the entire heart, two imaging sequences were performed.

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For each imaging sequencethe patient received approximately 70 ml of nonionic contrast medium delivered intravenously by a power injector. Imageswere obtained at end inspiration (breath holding lasted <25 seconds). Two observers who were blinded to other data used commercially available software (Imatron) to calculate cardiac chamber volumes and myocardial volume, which wasconverted to LV mass.These methodshave been pre2s,2gAtria1 end systole viously describedand validated. 15-17, wasdefined ascoincident with ventricular end diastole, and atria1 end diastole was defined as coincident with ventricular end systole. Diastolic and systolic LV wall stresswere calculated as previously described by using the following equation: stress= (P x r)/2h(l + h/2r), where P = pressure, r = radius, and h = wall thickness.30The radius and wall thickness were measuredon a midventricular shortaxis image. One patient who had aortic stenosis was excluded from this analysis. Total cardiac end-diastolic volume was calculated as the sum of the volumes at ventricular end diastole of all four chambersplus the volume of LV myocardium. Statistical analysis. Data are presentedas mean rt SD. Invasive hemodynamic values, which were obtained only before and immediately after MBC, were compared with Student’s paired t test. Values measuredat each of the three time points were comparedby using a repeated measures analysis of variance model, followed by multiple pairwise mean comparisonswith Tukey’s procedure with an experimental error rate of 0.05. Both parametric and nonparametric (signtest) techniques were usedto test the hypothesis that the mean percentage changefrom before MBC to immediately aft& MBC and from before MBC to 1 year after MBC was equal to zero. The two techniques yielded comparable results. Values obtained in patients and in normalswere comparedby using two-samplet tests with Bonferroni adjustment of each p value for the three comparisonsthat weremadebetweencontrols and patients (control vs before MBC, control vs immediately after MBC, control vs 1 year after MBC). For all analyses,p < 0.05was consideredto be statistically significant. RESULTS Cardiac catheterization (Table I). MBC successfully

decreased the mitral

valve gradient,

increased the

mitral valve area, and decreased the LA and pulmo-

nary artery pressures in all patients. The RA pressure (n = 10) tended to decrease. Oximetry performed after MBC in each patient demonstrated that three patients had a left-to-right interatrial shunt with &p/&s >1.5. No other complications occurred. Echocardiography

(Table II).

Echocardiography

demonstrated similar reductions in the mitral valve gradient, increases in mitral valve area, and reductions in LA diameter immediately and 1 year after MBC. The LA diameter decreased soon after MBC, and a further decrease at the 1 year follow-up was significant. An interatrial shunt was detected at the l-year follow-up in two of the three patients with

et al.

535

Table 1.Cardiac catheterization data beforeand after MBC After

Before

MV gradient(mmHg) MV area(cm? LA pressure(mmHg) PA pressure(mmHg) RA pressure(mmHg)§ MV, Mitral

valve; RA, right atrial. *p < 0.05 tp

11 1.1 22 29 6.5

i I 25 It 2

:i 0.3 3 9 2.3

LA, left atrial; PA, pulmonary

4 2.8 11 20 5.2 artery

-t 1t t 1.2$ t 4t +_ 4* t 2.4

(mean pressures;

< 0.0001

$p < 0.0005 @L= 10.

Table II. Echocardiographic data before, immediately after, and 1 year after MBC Before

MV gradient(mmHg) MV area(cm2) LA diameter(mm) MV, Mitral *n = 10.

valve;

823 1.2 c 0.2 52 t 6

After

1 year*

2.1 f 0.51 49 i 7

1.9 + 0.5$ 47 + 7s

4 + 2f

4 +- It

LA, left atrial.

tp = 0.0005 vs before. $p < 0.005 vs before. $p < 0.05 w before.

&p/&s > 1.5. Two patients had increased mitral regurgitation of two grades by Doppler echocardiography after MBC, one soon after MBC and one at the l-year follow-up. Cine CT (Table III). Comparison of cardiac chamber volumes in patients with volumes in normal controls. The reproducibility of measurements between the two observers was good. For example, for end-diastolic volumes, the r 2 values were as follows: LV 9 = 0.90, RV ? = 0.92, LA r 2 = 0.98, and RA r 2 = 0.91. When values obtained before MBC in patients were compared with values obtained in women with normal tine CT studies, neither the age (48 t 11 years vs 44 + 12 years) nor the body surface area (1.7 + 0.2 vs 1.8 -t 0.2 m2) was significantly different for the two groups. The mean total cardiac volume was larger in patients than in normals (529 +- 102 ml vs 379 + 52 ml; p < 0.0005). This increase was the result of significantly larger left and right atrial volumes. LA EDV and ESV remained significantly larger in patients both soon after and 1 year after MBC when compared with normal values (p < 0.0005 for soon after and p < 0.001 for 1 year after MBC), as did RA EDV (p = 0.005 for soon after and p < 0.001 for 1 year after MBC), as did RA ESV (p < 0.005 soon after MBC; p < 0.005 1 year after MBC).

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Table III. Cine CT volumes and hemodynamic data in patients and in controls before and after mitral balloon commissurotomy Before LA EDV (ml) LA ESV (ml) LA SV (ml) LV EDV (ml) LV ESV (ml) LV SV (ml) RA EDV (ml) RA ESV (ml) RA SV (ml) RV EDV (ml) RV ESV (ml) RV SV (ml) TV EDV (ml) CI (L/min/m2) LV EF (%) RVEF (%) LV my0 (ml) HR (beatdmin) SBP (mm Hg) DBP (mm Hg) SWS (gm/cm2)ll

DWS (gm/cm2)11

186 143 43 102 29 73 100 58 43 119 42 77 529 3.1 73 65 107 76 121 67 187 119

+ f k k -c + + k i k + f k + + + * + * + f f

After 59 52 14 24 17 13 31 23 16 23 15 16 102 0.5 11 10 22 11 13 13 36 24

166 119 47 107 28 79 118 66 52 144 43 98 545 3.4 75 70 111 78 110 66 185 115

1 year

-t 49 + 447 + 13 t 32 rf: 15 t 20 +- 34 + 28 ?I 19 * 24 * 11 k 21 -c 110 -e 0.7 + 8 do 6 + 21 -+ 14 * 17 k 16 k 60 f 34

158 102 55 119 27 92 119 62 56 148 44 104 552 3.4 78 71 121 67 136 75 207 133

f IL k -t r + 2 + -c + + * +_t + + t i + 2 f 2

52t 39t 2ot 34 16 21t 29 25 147 46 16 34t 132 0.7 7t 7t 30tf 10’S 22$ 11 60 47

Controls 72 31 40 94 20 74 74 28 46 115 41 74 381 3.0 79 65 113 73

_t + + k f + k k i * + IL + fc + k k i

*

14t$§ 8tt§ 10 17 6 14 lS$§ 6t$§ 13 22$ 11 16$ 50t*s 0.9 5 7 18 9

Values are mean + S.D. Exact p values listed in text. For simplicity all values are listed asp < 0.05. SV, Stroke volume; TVEDV, total cardiac end-diastolic volume; Cl, cardiac index; EF, ejection fraction; myo., myocardial volume at end-diastole; HR, heart rate; SBP, systolic blood pressure; DBP, diastolic blood pressure; SK’S, systolic wall stress; DE’S, diastolic wall stress. *Analysis performed with a two-sample t test to compare controls with patients. tp < 0.05 vs before. fp < 0.05 vs after. §p < 0.05 vs 1 year. Iln = 10.

Changes with mitral

in cardiac chamber volumes in patients stenosis after MBC. Soon after MBC, LA

EDV tended to decrease and the LA ESV decreased significantly (p < 0.01). Further decreases in LA ESV (p < 0.0005) and LA EDV 0, < 0.01) 1 year after MBC and the increase in LA SV (p < 0.05) were significant. Although the mean LV ESV remained remarkably constant, LV SV increased at 1 year @ < 0.025) and the increase in LV EDV approached significance (p = 0.056). Although heart rate decreased 1 year after MBC (p < 0.05), cardiac index was unchanged. Total cardiac volume was essentially unchanged. Soon after and 1 year after MBC, RA ESV was unchanged. The slight increase in RA EDV was associated with a significant increase in RA SV by 1 year after MBC (p < 0.025). RV EDV tended to increase immediately after MBC, and by 1 year after MBC the increase approached significance (p = 0.057). Similar to LV ESV, RV ESV was remarkably constant. The relative changes in cardiac chamber volumes are depicted as percentage of change from before MBC in Fig. 1. These data demonstrate that the sig-

nificant relative decrease in LA ESV soon after MBC was associated with a significant relative increase in RV EDV. At 1 year follow-up, these relative decreases in LA ESV progressed and were associated with further significant increases in LV and RV EDV; total cardiac volume remained essentially unchanged. With respect to other variables in Table III, the left and right ventricular ejection fractions were significantly higher at the l-year follow-up study compared with before MBC, as was LV myocardial volume (the corresponding LV mass was: 63 * 11 gm/m2 vs 66 + 10 gm/m2 vs 71 -t 12 gm/m2, 1 year p < 0.005 vs before; p < 0.05 vs after). Systolic blood pressure was significantly higher at 1 year compared with soon after MBC (p < 0.005), and diastolic blood pressure was unchanged. The systolic and diastolic LV wall stress progressively increased by 1 year. To further analyze these changes, we individually examined the few patients with mitral regurgitation or an interatrial shunt with Qp/Qs > 1.5. In one of the two patients with increased mitral regurgitation of two grades, minimal changes in chamber volumes occurred; in the other patient the changes paralleled

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Grover-McKay

those of the group as a whole. Changes in cardiac volumes by tine CT were analyzed separately for the three patients with &p/&s > 1.5; they showed that in one patient in whom the shunt was not present at 1 year, LA volume changed minimally. In the two patients with persistent shunts, changes in cardiac chamber volumes paralleled those of the entire group. DISCUSSION

In this group of patients with mitral stenosis, mean total cardiac volume was larger than values obtained in gender-matched controls of comparable age. The larger total cardiac volume was the result of an increase in LA and RA volumes. Immediately after MBC the decrease in LA volume is associated with an increase in RV volume, a surprising finding given the decrease in pulmonary artery pressure and RV afterload and a slight decrease in RA pressure. At l-year follow-up, these changes in chamber volumes continued; in addition, LV mass increased. Total cardiac volume remained essentially unchanged. Most of the previous studies of left ventricular volumes and mass after relief of mitral stenosis were performed after surgery when the pericardium had been opened and the chordal and papillary muscle apparatus may have been altered.ga lo, 31p32 These studies demonstrated a trend toward an increase in LV volumes and mass. However, these results may not apply to patients undergoing MBC because LV contraction, and therefore chamber volume, may be affected by the presence of an intact mitral valve apparatus. I1 In addition, development of ventricular hypertrophy may be affected by the presence of an intact pericardium.i3 In a study with echocardiography, LV end-diastolic volume, stroke volume, and mass increased after MBC; however, right-sided cardiac chamber volumes and LV wall stress were not measured.‘* We observed significantly decreased LA ESV soon after MBC. One year after MBC, LA EDV also decreased and LV EDV tended to increase. Recently Liu et al.33 demonstrated acute reversal of impaired LV diastolic function by MBC. This release of intrinsic restriction and the increased mitral valve opening may both be factors related to the changes in cardiac chamber volumes we observed. Our data suggest that some remodeling (i.e., changes in cardiac chamber volumes and mass) occurs in addition to the effects documented by Liu et al. An interesting finding of our study is that the decrease in LA volume after MBC is offset by an increase in RV volume. Despite the significant decrease in pulmonary artery pressure after MBC, the right ventricle and atrium

70 50 50 40 30

et al.

LA ESV

LV EDV

RA ESV

RV EDV

537

i TT N “1 P

EDV

-

15 10 5 0 liLiz/L

Fig. 1. Percentage of change in cardiac chamber volumes relative to value in each chamber before MBC. Percentage of change immediately after MBC (solid bars) and 1 year after MBC (hatched bars) are shown. *p < 0.001 and tp < 0.05 vs before.

did not get smaller, and the total cardiac volume was not significantly different. Although we did not measure pulmonary artery pressures at 1 year, others have demonstrated a persistent decrease with successful MBC.34 Therefore it is unlikely that elevated pulmonary artery pressures explain why right-sided chamber volumes increased after successful MBC. Measurement of RV mass would be of interest. Although it is possible to measure RV mass with 3 mm thick tine CT images,35 this requires a separate imaging sequence that would increase the amount of contrast and radiation received by the patient. Our patients did not systematically have these images obtained before and after MBC. Comparison of RA and RV volumes in patients before MBC to values in controls demonstrated that RA volumes were larger in patients, whereas RV volumes were comparable. Soon after MBC, RV EDV increased and was significantly larger than the mean value obtained in normals. Thus with progressive mitral stenosis, the LA and RA enlarge in patients. After relief of mitral stenosis, LA size decreases, RA size does not change, and RV EDV increases.

538

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et al.

This study documents the redistribution of total cardiac volume with progressive mitral stenosis and the changes in distribution of the individual chamber volumes after MBC. The significant decrease in LA volume that occurs after MBC is expected given the significant decrease in mitral valve gradient and increase in mitral valve area. The decrease in LA volume may be associated with an increase in LA compliance, hence with altered LV load. The changes in LV wall stress and heart rate probably can contribute to the increase in LV EDV and LV mass observed 1 year after MBC. The interesting finding of our study is that in these patients, most of whom did not have a significant residual interatrial shunt or mitral regurgitation, and despite a significant decrease in pulmonary artery pressure after MBC, the RV volume increased and the total cardiac volume remained unchanged. Hoffman and Ritman36 observed that end-systolic total heart volume (defined as total contents of the pericardial sac) remains within 5% of end-diastolic volume. This observation demonstrated an important reciprocal role between atria1 and ventricular volumes whereby the atrioventricular valve plane moves toward the apex in systole and the epicardial apex remains fixed. In our study the importance of reciprocity between atria1 and ventricular volumes is highlighted by the fact that the LA volumes decreased; the RV end-diastolic volume tended to increase despite a significant reduction in RV afterload. Furthermore, if the decrease in LA volumes is accompanied by increased LA compliance, the descent of the atrioventricular valve plane may be greater in systole, thereby increasing LV stroke volume. It is purely speculative that the changes in RV and LV EDV might be different with respect to maintenance of total heart volume, in part because the thinner walls of the RV might permit an alteration in volume more readily than the thicker walls of the LV. In conclusion, these observations provide information about the effect of MBC on all four cardiac chamber volumes and left ventricular myocardial volume, thereby providing insight into the interrelation of these volumes. We thank Dr. Eric Hoffman for his suggestions, Marilyn Krachmer for her help, and Marlene Blakley for preparing the manuscript.

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Percutaneous balloon valvotomy for patients with severe mitral stenosis. Circulation 1987;75:778-84. 3. McKay CR, Kawanishi DT, Rahimtoola SH. Catheter balloon valvuloplasty of the mitral valve in adults using a double balloon technique. JAMA 1987;257:1753-61. 4. McKay RG, Lock JE, Safian RD, Comb PC, Deiver DJ, Bairn DS, Berman AD, Warren SE, Mandell VE, Royal HD, Grossman W. Balloon dilation of mitral stenosis in adult patients: postmortem and percutaneous mitral valvuloplasty studies. J Am Co11 Cardiol 1987;9:723-31. 5. McKay CR, Kawanishi DT, Kotlewski A, Parise K, OdomMargoon T, Gonzales A, Reid CL, Rahimtoola SH. Improvement in exercise capacity and exercise hemodynamics 3 months after double balloon, catheter balloon valvuloplasty treatment of patients with symptomatic mitral disease. Circulation 1988;77:1013-21. 6. The NHLBI Balloon Valvuloplasty Participants. Multicenter experience with balloon mitral commissurotomy: NHLBI Balloon Valvuloplasty Registry report on immediate and 30day follow-up results. Circulation 1992;85:445-61. 7. Curry GC, Elliot LP, Ramsey HW. Quantitative left ventricular angiocardiographic findings in mitral stenosis. Am J Cardiol 1972;29:621-7. 8. Newman GE, Rerych SK, Bounous PE, Upton MT, Jones RH. Noninvasive assessment of hemodynamic effects of mitral valve commissurotomy during rest and exercise in patients with mitral stenosis. J Thorac Cardiovasc Surg 1979,78:750-9. 9. Chiang C, Chang C, Lee Y, Hsu T. Cardiac dimensions and motion shortly after mitral valve surgery. Jpn Heart J 1984; 25:509-21. 10. Kazama S, Nishiguchi K, Sonoda K, Nagajima H, Kawai Y, Mai H, Asari H, Ishihara A. Postoperative left ventricular function in patients with mitral stenosis: the effect of commissurotomy and valve replacement on left ventricular systolic function. Jnn Heart J 1986:27:35-42. 11. Yagyu K, Matsumoto H, Asano K. Importance of the mitral complex in left ventricular contraction: an analysis of the results of mitral valve replacement with preservation of the posterior mitral complex. Thorac Cardiovasc Surg 1987;35: 16601 12. %nsen DE, Sarris GE, Niczyporuk MA, Derby GC, Cahill PD, Miller DC. Physiologic role of the mitral apparatus in left ventricular regional mechanics, contraction synergy and global systolic performance. J Thorac Cardiovasc Surg 1989; 97:521-33. effects 13. Cooksey JD, Bonce J. Cardiac hypertrophy: synergistic ^of pericardiectomy and mild exercise in rats. Proc Sot Exp Biol Med 1975;149:559-61. 14. Tischler MD, St John Sutton M, Bittle JA, Parker JD. Effects of percutaneous mitral valvuloplasty on left ventricular mass and volume. Am J Cardiol 1991;68:940-4. 15. Feiring AJ, Rumberger JA, Skorton DJ, Collins SM, Lipton MJ, Higgins CB, El1 S, Marcus ML. Determination of left ventricular mass in the dog with rapid-acquisition cardiac CT scanning. Circulation 1985;72:1355-65. 16. Reiter SJ, Rumberger JA, Feiring AJ, Stanford W, Marcus ML. Precision of right and left ventricular stroke volume measurements by rapid acquisition ultrafast computed tomography. Circulation 1986;74:890-900. 17. Roig E, Georgiou D, Chomka EV, Wolfkiel C, LoGalbo-Zak C, Rich S, Brundage BH. Reproducibility of left ventricular myocardial volume and mass measurements by ultrafast computed tomography. J Am Co11Cardiol 1991;18:990-6. 18. Marcus ML, Weiss RM. Evaluation of cardiac structure and function with ultrafast computed tomography. In: Marcus ML. Schelbert HR. Skorton DJ, Wolf GL, eds. Cardiac imaping,‘Philadelphia: WB Saunders, 1991:669-81. _--19. Smith MD. Handahoe R. Handshoe S, Kwan OL, DeMarin AN. Comparative accuracy of 2-dimensional echocardiography and Doppler pressure half-time methods in assessing severity of mitral stenosis in patients with and without prior commissurotomy. Circulation 1986;73:100-7. 20. Helmcke F, Nanda NC, Hsiung MC, Soto B, Adey CK, Goyal

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Transcatheter occlusion of patent ductus arteriosus by Rashkind umbrella device: Follow-up results Seventy-six patients (36 boys and 40 gitis) with patent ductus arteriosus who had successful ductal occlusion with a Rashkind umbrella device were monitored for a period of 6 to 60 months (mean 26.7 f 12.3 months). All patients were evaluated by pulsed and color Doppler echocardiography before and after the procedure. The prevatence of residuei k&to-right shunt and main pulmonary artery flow pattern were assessed. Residual left-to-right ahunt was seen in 12 (15.7%) patients 24 hours after the procedure, but the shunt was small with a pulmonary-to-systemic blood flow ratio of c1.3:1. Repeat echo Doppler study at 14 days showed residual left-to-right shunt in 10 (13.1%) patients. None of these patients showed further decrease in prevalence of residual left-to-right shunt. The patients w#th residual left-to-right shunt had larger ductii (mean 5.17 t 0.88 mm, range 4.23 to 6.8 mm) as compared to patients with no residual left-to-right shunt (3.31 f 0.86 mm, range 1.8 to 4.69 mm; p < 0.001). Two patients with residual shunt had successful ductus reocclusion, with 12 and 17 mm devices, respectively, at 28 month of follow-up. The Rashkind umbrella device is effective in closing ducti with diameters of < 5 mm in majority of patients. (AM HEART J 1994;128:539-41.)

R. Arora, DM, G. S. Kalra, DM, M. Nigam,

MCH,

and M. Khalillulah,

DM

New Delhi, India

From the Department of Cardiology, G. B. Pant Hospital. Received for publication May 17, 1993; accepted Dec. 13, 1993.

Hospital, New Delhi, India 110002. Copyright @1994 by MO&y-Year Book, Inc.

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