percutaneous dilatation valve - heart

Br Heart J 1988;60:299-308

Percutaneous balloon dilatation of the mitral valve:an analysis of echocardiographic variables related to

outcome and the mechanism of dilatation

GERARD T WILKINS, ARTHUR E WEYMAN, VIVIAN M ABASCAL,PETER C BLOCK, IGOR F PALACIOS

From the Cardiac Unit, Department of Medicine, Massachusetts General Hospital, and Harvard MedicalSchool, Boston, Massachusetts, USA

SUMMARY Twenty two patients (four men, 18 women, mean age 56 years, range 21 to 88 years)with a history ofrheumatic mitral stenosis were studied by cross sectional echocardiography beforeand after balloon dilatation of the mitral valve. The appearance of the mitral valve on the pre-

dilatation echocardiogram was scored for leaflet mobility, leaflet thickening, subvalvar thickening,and calcification. Mitral valve area, left atrial volume, transmitral pressure difference, pulmonaryartery pressure, cardiac output, cardiac rhythm, New York Heart Association functional class, age,and sex were also studied. Because there was some increase in valve area in almost all patients theresults were classified as optimal or suboptimal (final valve area < 1 0 cm2 final left atrial pressure> 10 mm Hg, or final valve area < 25% greater than the initial area). The best multiple logisticregression fit was found with the total echocardiographic score alone. A high score (advanced leafletdeformity) was associated with a suboptimal outcome while a low score (a mobile valve with limitedthickening) was associated with an optimal outcome. No other haemodynamic or clinical variablesemerged as predictors of outcome in this analysis. Examination of pre-dilatation and post-

dilatation echocardiograms showed that balloon dilatation reliably resulted in cleavage of thecommissural plane and thus an increase in valve area.

Percutaneous balloon dilatation ofthe mitral valve isa promising new approach to the management ofrheumatic mitral stenosis.1w But at this early stagelittle is known about the criteria for patient selectionor the mechanism by which balloon dilatationincreases mitral valve area. Previous experience withclosed surgical commissurotomy suggests that mitralvalve pliability and the degree of leaflet thickeninghave an important effect on subsequent outcome.'""Because cross sectional echocardiography shows thestructure of the mitral apparatus, the severity of thestenotic lesion, and changes in chamber size"617 itshould provide information that will predict thelikely outcome of balloon dilatation.

Patients and methods

We studied the first 22 patients (four men and 18women) who had percutaneous balloon dilatationRequests for reprints to Dr Arthur EWeyman, Cardiac NoninvasiveLaboratory, Phillips House 8, Massachusetts General Hospital,Fruit Street, Boston, MA 02114, USA.

Accepted for publication 24 February 1988

of the mitral valve at the Massachusetts GeneralHospital. They were aged from 21 to 88 years(mean 56-6). All patients had a diagnosis ofrheumaticmitral stenosis on the basis of history and clinicalexamination.To identify features that might predict the result of

balloon dilatation we analysed 18 variables assessedat the clinical, echocardiographic, and haemo-dynamic examinations performed before theprocedure. The clinical variables included cardiacrhythm, New York Heart Association functionalclass, age, and sex. From the echocardiogram weassessed structural features of the mitral valve andsubvalvar apparatus, including the initial mitralvalve area (by planimetry), initial left atrial size, andthe pre-valvotomy grade of mitral regurgitation (byDoppler echocardiography). The haemodynamicfeatures measured at catheterisation before balloondilatation included mitral valve area, transmitralpressure difference, cardiac output, pulmonary vas-cular resistance, and left ventricular end diastolicpressure. The degree of mitral calcification was alsoassessed by radiology.

299

on Novem

ber 29, 2021 by guest. Protected by copyright.

http://heart.bmj.com

/B

r Heart J: first published as 10.1136/hrt.60.4.299 on 1 O

ctober 1988. Dow

nloaded from

http://heart.bmj.com/

300 Wilkins, Weyman, Abascal, Block, Palacios

Table 1 Individual clinical, haemodynamic, and echocardiographic resultsfor the study group

MVA- MVA-NYHA MVA-pre MVA-post Grad Grad Pre Post PA PA Total* pre post

Patient Age Sex Rhythm class Gorlin Gorlin pre post LA-P LA-P pre post Outcome score echo echo

67 M SR71 M AF72 F AF57 F SR56 F SR49 F AF40 F SR42 F SR59 F SR40 F SR88 F AF27 F SR71 F AF47 F SR68 F AF64 F AF72 F SR21 M SR78 F AF51 M SR53 F AF54 F SR

IVIIIIIIIIIIIIIIIIIIIIIVIIIIVIIIIVIIIIVIIIIVIIIIVIIIIIIIV

0-70-70-91-61-0080-71-10-41-00-50-70-5080-70-60-90-6040-61-40-5

251*51 729221*5201 31 6231-0281 22 1081*51 71 8t2 11 609

2012915189

3028222515241820912171520251631

4 42 25 50 40 Sub 14 0 58 22 19 52 38 Sub 10 1 25 15 10 21 18 Opt 6 186 15 10 25 20 Opt 9 145 25 5 34 14 Opt 7 0 95 17 18 31 35 Sub 9 1.06 38 10 75 35 Opt 5 1.014 32 18 40 25 Sub 9 1.02 20 10 48 15 Opt 11 045 30 7 40 25 Opt 5 0 84 35 20 52 35 Sub 14 0 84 30 8 42 18 Opt 7 0-75 22 17 53 40 Sub 16 t7 32 10 40 28 Opt 5 1.18 20 12 50 40 Sub 10 0 85 18 10 45 35 Opt 11 0 84 21 22 30 t Sub 10 0 93 22 6 35 20 Opt 4 0 6

35 40 $ Sub 12 0 45 25 5 36 25 Opt 10 0 5

12 21 12 32 17 Sub 11 1 411 39 12 62 29 Sub 11 1.1

SR, sinus rhythm; AF, atrial fibrillation; NYHA, New York Heart Association functional class; MVA-pre and MVA-post, Gorlin mitral valve area before andafter balloon dilatation; Grad pre and Grad post, mean transmitral gradient before and after balloon dilatation; Pre LA-P and post LA-P, mean left atrialpressure before and after balloon dilatation; PA pre and PA post, mean pulmonary artery pressure before and after balloon dilatation; MVA-pre and MVA-post, echocardiographic mitral valve area before and after balloon dilatation; *total echocardiographic score; tTechnically limited measurements;$Measurements not performed because of acute haemodynamic deterioration.

CLINICAL FEATURES were performed within three months. To analyse theOf the 22 patients, 13 were in sinus rhythm and 9 effect of mitral valve structure on the results ofwere in atrial fibrillation. By the New York Heart dilatation, we scored the echocardiographic study ofAssociation functional class, one (5%) patient was in each patient for: (a) leaflet mobility, (b) leafletclass II, 13 (59%) were in class III, and 8 (360%) were thickening, (c) subvalvar thickening, and (d) cal-in class IV. cification. Table 2 shows the scoring system. We gave

each of the above features a score of 0-4, and higherECHOCARDIOGRAPHIC FEATURES scores represented more abnormal structure. ForEach patient was studied by cross sectional and example, for mobility, grade 1 was a highly mobileDoppler echocardiography before the procedure. valve with restriction of only the leaflet tips. Grade 4Most studies (20 of 22, 91 O) were performed within indicated a valve that was almost completely24 hours of the procedure; the remaining two studies immobile with no (or minimal) forward movement

Table 2 Grading of mitral valve characteristicsfrom the echocardiographic examination

Grade Mobility Subvalvar thickening Thickening Calcification

1 Highly mobile valve with only Minimal thickening just Leaflets near normal in A single area of increasedleaflet tips restricted below the mitral leaflets thickness (4-5 mm) echo brightness

2 Leaflet mid and base portions Thickening of chordal Mid-leaflets normal, Scattered areas of brightnesshave normal mobility structures extending up to considerable thickening of confined to leaflet margins

one third of the margins (5-8 mm)chordal length

3 Valve continues to move Thickening extending to the Thickening extending Brightness extending into theforward in diastole, distal third of the through the entire leaflet mid-portion of themainly from the base chords (5-8 mm) leaflets

4 No or minimal forward Extensive thickening and Considerable thickening of all Extensive brightnessmovement of the leaflets shortening of all chordal leaflet tissue ( >8-10 mm) throughout much ofin diastole structures extending down the leaflet tissue

to the papillary muscles

The total echocardiographic score was derived from an analysis of mitral leaflet mobility, valvar and subvalvar thickening, andcalcification which were graded from 0 to 4 according to the above criteria. This gave a total score of 0 to 16.

2345678910111213141516171819202122

1 8t242-01 61*52 11 51 4201 624t2 1081.11 71 8

231 61 2

on Novem



/B


ctober 1988. Dow

nloaded from


Percutaneous balloon dilatation of the mitral valve

i. . . .I.N.

Fig 1 (a) Ehocardiographic parastenal long axis view showing a highly mobile, "doming" anterior (AML)andposterior (PML) mitral valve with slightly thickened leaflet tips. There is no evidence ofsubvalvarthickening. The echo score is 4. (b) The mitral leaflets are thickened and this thickening (SVTh) extends belowthe leaflet tips into the subvalvar apparatus. The echo score is 11.

during diastole (figs 1 and 2). Summing theindividual scores resulted in a total echocardiogra-phic score. According to this system, a score of 0would be a totally normal valve (no such valve wasincluded in this series), while a score of 16 wouldrepresent an immobile valve with considerable thick-ening of the leaflets and subvalvar apparatus andsevere superimposed calcification.

Subvalvar thickening was best displayed by aseries of modified views. In the parasternal long axisview, the standard aligned view was tilted mediallyand laterally so that the long axis of each papillarymuscle and its attached chordal apparatus could beexamined in turn. From the apical window, theextent of subvalvar shortening and scar was bestviewed in a four chamber view with the transducerangled more posteriorly into the left ventricle, orfrom a foreshortened two chamber view angledmedially and laterally.The left atrial volume was calculated from the

echocardiographic images before and after the

procedure by an ellipsoid formula, in which thelength was taken as the superior-inferior length oftheatrium in the apical four chamber view and the twodiameters used were the anterior-posterior andmedial-lateral dimensions measured in the paraster-nal long and short axis views respectively (fig 3). Theanterior-posterior diameter (D1, fig 3a) and thesuperior-inferior length (D3, fig 3c) were measuredin the frame obtained immediately before mitralvalve opening. The medial-lateral diameter (D2, fig3b) was measured in a view in which the mitral valvecannot be seen in the frame during which aortic valveclosure was completed. Mitral valve area wasmeasured by direct planimetry in the standardmanner" 7 before and within 24 hours of theprocedure (fig 4). Technically satisfactory images ofthe mitral valve orifice suitable for planimetry couldnot beobtained either before or after the procedure inone patient and after the procedure in another(patients 13 and 2 respectively, table 1). The presenceand extent of mitral regurgitation were also mapped

301

on Novem



/B


ctober 1988. Dow

nloaded from


Wilkins, Weyman, Abascal, Block, Palacios

0

©@

Fig 2 (a) Echocardiographic apicalfour chamber view showing "doming" of the mitralvalve with slight thickening of the anterior (AMVL) and posterior (PMVL) leaflet tips.The echo score is 4. (b) Extensive thickening of the leaflets (MVL) and a considerableincrease in echo density suggesting the presence of calcification. The echo score is 14.

before and after the procedure by the pulsed Dopplertechnique in order to assess any adverse effect of thisvariable on outcome.18 Mitral regurgitation wasgraded on a scale of 1 to 4+ by dividing the atriuminto four equal segments along its long axis andconstructing an arc centred at the mid-point of themitral valve that extended from the end of eachquadrisecting point to the medial and lateral walls ofthe atrium. High velocity systolic flow was thengraded according to its penetration into these seg-ments. Grade 4 represented flow detected at the viostsuperior atrial segment.

HAEMODYNAMIC VARIABLESEach patient was catheterised from the right femoralapproach. The interatrial septum was first crossed bythe Brockenborough technique. A flow directedcatheter was then passed through the transseptalsheath and, together with a flexible exchange guidewire, advanced through the mitral valve orifice. Leftatrial and left ventricular pressures were measured,and the mean transmitral pressure difference wascalculated. Pulmonary artery pressure was measuredwith a Swan-Ganz catheter inserted via the internal

jugular vein. Cardiac output was measured by ther-modilution, Fick, or green dye dilution techniques.We calculated the mitral valve area by the Gorlinequation.'9

After these haemodynamic measurements, per-cutaneous balloon dilatation of the mitral valve wasperformed by either a single or double balloondilating technique.7 A single balloon procedure wasperformed in 17 patients: a single 15 mm balloon inone, a single 20 mm balloon in one, and a single25 mm balloon in 15 patients. In four patients adouble balloon procedure was performed with acombination of a 25 mm and 15 mm balloon. Oncethe catheter(s) was positioned across the orifice, theballoon(s) was inflated by hand until the indentationcaused by the stenotic mitral valve disappeared. Eachinflation lasted approximately 15 seconds and multi-ple inflations were performed in all patients. In onepatient (patient 19, table 1) the valve could not becrossed with an 8 mm balloon catheter, and thepatient became profoundly hypotensive. Mitral valvereplacement was uneventful, but the patient couldnot be weaned from cardiopulmonary bypass becauseof profound right heart failure and she died.

30)2

on Novem



/B


ctober 1988. Dow

nloaded from



Left atrial volume 4n Dl. D2 D33 2 22

Fig 3 The derivation of the orthogonal diametersfrom which the kft atrial volume was calculated. (a) Theanterior-posterior diameterfrom the parasternal long axis view. (b) The medial-lateral diameterfrom theparasternal short axis view. (c) The superior-inferior diameterfrom the apicalfour-chamber view. Thesediameters were used to calculate the left atrial volumefrom an ellipsoid-biplane formula (d).

FLUOROSCOPIC CALCIFICATIONThe grade of mitral calcification was assessed by thefluoroscopic examination conducted at catheterisa-tion. The grade was qualitatively scored from 0 (nocalcification seen) to 4 (severe calcification).

STATISTICAL ANALYSISTo determine whether any variable or combinationof variables predicted a successful outcome ofballoon dilatation, all echocardiographic, Doppler,haemodynamic, and clinical data were analysed bymultiple logistic regression analysis. The dependentvariable was either an optimal or a suboptimal result.A suboptimal result was defined as any one or more ofthe following: (a) a final valve area < 1-0 cm2, (b) apost-dilatation mean left atrial pressure > 10 mmHg, or (c) a change in area < 25% of the initial valvearea in those with a mitral valve area > 10 cm2 beforethe procedure.One patient (case 19, table 1) who died soon after

attempted percutaneous mitral balloon dilatation was

included in the analysis on the basis of intention totreat.

Multiple logistic regression analysis was per-formed in the standard manner with a commercialstatistical package, BMDP.' Data are presented asmean (1 SD). The outcome in the subgroups(optimal v suboptimal) was compared by theunpaired Student's t test for parametric data or theWilcoxon signed rank test for non-parametric data.The frequency of events was compared by the x2 orFisher's exact test. Interobserver variability wasdetermined from the mean unsigned differencesbetween two sets ofmeasurements performed blindlyby two experienced observers. Intraobservervariability was determined in the same way from twosets of measurements performed by the sameobserver on different days.

Results

Table 1 shows the clinical, echocardiographic, and

303

on Novem



/B


ctober 1988. Dow

nloaded from



Fig 4 An echocardiographic parasternal short axis view of the mitral valve orifice in diastole (patient 16, table 1). Thesmall central orifice (MVO) is surrounded by the circular outline of the left ventricular cavity. The margins of the centralorifice were electronically traced and the mitral valve area (0-6 cm2) was calculated by planimetry.

haemodynamic variables for each patient.The mean valve area measured by planimetry of

the cross sectional echocardiographic short axisimages before balloon dilatation was 0 9 (0-46) cm'

(range 0-40-1-8 cm'). After dilatation, the mean areaincreased to 1-7 (0-45) cm' (range 0-81-2-4 cm',p < 0-0001). The individual increases in valve area

varied considerably, and ranged from 0-1 to 1-81 cm'.

The mean valve area measured by the catheterisa-tion method (Gorlin equation) before balloon dilata-tion was 0-8 (0 30) cm' (range 0-41-6 cm'). Afterballoon dilatation, the mean area increased to1-76 (0-6) cm' (range 0-82-9 cm', p < 0-0001).Changes in valve area measured by the planimetrymethod and by the Gorlin equation were stronglycorrelated (r = 0 9, p < 0-001).Table 1 shows total echocardiographic score for

leaflet mobility, leaflet thickening, leaflet calcifica-tion, and subvalvar thickening for each patient beforeballoon dilatation. On a scale of 0 to 16, representingincreasing structural deformity, the severity rangedwidely from 4 to 16 (mean grade 9 4 (3 1)). In 12randomly selected cases, the mean interobservervariability for the total echocardiographic score was0-41 (0X51). The intraobserver variability for theechocardiographic score in the same patients was

0-38 (04).The mean grade of regurgitation by Doppler was

1-0 (1-2) with a range of 0 to 3. After dilatation, themean grade ofregurgitation increased to 1-8 (1 1) andranged from 0 to 3. Although this increase in thedegree of regurgitation (by Doppler) represented a

significant increase (p < 0-01), no patient developedgrade 4 regurgitation. Mean left atrial volume was 95(47) cm3 (range 52-220 cm3), which was significantlylarger than the normal values of 32 (10) cm'

previously reported from our laboratory.2' Afterdilatation the mean left atrial volume decreasedsignificantly to 83 (12) cm3 (p < 0.001).

16

12-

o0u

~0

0-

X = 12.1p=0. 001

0 0

0

0

0

0 0

0

0

0 0

00

Optimalresult

Suboptimalresult

Fig 5 Total echocardiographic scorefor each patient (from0 to 16) in patients grouped according to outcome. The barshows mean total scorefor each group. Logistic regressionanalysis according to outcome selected the totalechocardiographic score alone as the best predictor.

304

5 N

on Novem



/B


ctober 1988. Dow

nloaded from



Fig 6 Cross sectional echocardiographic imagesfrom study patient 12 (table 1)immediately before and 24 hours after balloon dilatation of the mitral valve. (a) Thesmall central orifice (0 7 cm2) (MVO pre). After the procedure, the orifice (MVO post)was significantly larger (2 4 cm2) (b) with cleavage along the medial and lateralcommissures which had previously appeared as dense scarred regions.

The mean grade of calcification (by fluoroscopy)was 1-4 (1-5) and ranged from grade 0 to 4. Tenpatients had no obvious calcification ofthe leaflets byfluoroscopic examination and only one had grade 4calcification.The haemodynamic data showed a mean trans-

mitral pressure difference of 18-6 (6 6) mm Hg,mean cardiac output of 3-9 (1-2 1/min), mean pul-monary vascular resistance of 384 (289) dynes.s.cm5 , and a mean left ventricular end diastolicpressure of 8 (3) mm Hg.The mean dilating area of the balloon(s) was

4-89 cm2 (approximately equal to a single 25 Frenchballoon).

ANALYSIS FOR PREDICTORS OF AN OPTIMAL ORSUBOPTIMAL RESULTThere were 11 patients with an optimal result and 11patients with a suboptimal result (see Methodssection for criteria).Comparison of the mitral valve structure in the

groups with optimal and suboptimal outcomeshowed significant differences in the degrees of valvemobility (mean optimal group 1-8 (0 96) and meansuboptimal group 3-18 (0-75), p < 0-001), valvethickening (mean optimal group 2 1 (0-8) and meansuboptimal group 3-2 (0-6), p < 01001), subvalvarthickening (mean optimal group 1-7 (0-6) and meansuboptimal group 2-5 (0-8), p < 0-01), and valvecalcification (mean optimal group 1 8 (0-9) and meansuboptimal group 2-6 (0-8) p < 0 03). The totalechocardiographic score was also significantlydifferent in the two groups (mean optimal group 7-36(2 5) (range 4-11) and suboptimal group 11-5 (2 3)(range 9-16), p < 01001), with an optimal outcomeassociated with a lower score (fig 5).

Analysis of the clinical variables showed that themean New York Heart Association functional classwas lower (optimal 3-0 (0-4) and suboptimal 3-63(0 5), p = 01005) and the mean fluoroscopic grade ofcalcification was lower (mean optimal grade 0-5 (1 0)and mean suboptimal grade 2-3 (1-4), p = 0-003) in

305

on Novem



/B


ctober 1988. Dow

nloaded from


306

the optimal result group. The frequency of sinusrhythm or atrial fibrillation was not significantlydifferent in the groups with optimal and suboptimaloutcome, although there was a trend towards a higheroccurrence of sinus rhythm in the optimal outcomegroup (p = 0 08). No difference was found in the sexdistribution of the two groups.For the remaining variables the two outcome

groups showed no difference in initial left atrialvolume, initial valve area, or the Doppler grade ofmitral regurgitation. The effective balloon dilatingarea used was not different (although there was atrend towards an optimal result with larger effectiveballoon areas such as those previously reported7).The order in which the patients had their interven-tion performed was analysed to determine whether alearning curve affected outcome; this showed nodifference between the two groups in mean positionwithin the series. No difference was noted betweenthe two groups for the initial transmitral gradient,cardiac output, or pulmonary artery pressure andresistance.

MULTIPLE LOGISTIC REGRESSION ANALYSIS FORTHE MAJOR PREDICTOR(S) OF OUTCOMEWhen multiple logistic regression analysis was per-formed with the outcome as the dependent variable(optimal v suboptimal), the total echocardiographicscore on its own was found to be the best predictor(multiple x2 = 12-1, p < 0 0001). The fit of thelogistic regression was not improved by the additionof any other variable. Figure 5 shows the individualtotal echocardiographic scores for each patient andthe outcome group to which each individual belongs.Although four patients with relatively high scores(that is significant immobility, thickening, andsubvalvar thickening) had an optimal result. Ingeneral, however, the analysis suggested that a highscore was associated with a suboptimal outcome.

ANALYSIS FOR THE MECHANISM OF DILATATIONCareful examination of the short axis echocardiogra-phic images showed that successful balloon dilatationofthe mitral valve was associated with cleavage alongthe commissures (fig 6). This appearance occurredeven in those patients who had significantly thick-ened and calcified valve leaflets, although the degreeof cleavage was less. Balloon dilatation in somepatients with high total echocardiographic scoresseemed to produce extensive commissural splitting,but, despite this, the separation of the leaflets indiastole remained poor. So the orifice area failed toincrease relative to the increase in circumference,presumably because the deformed leaflets were un-able to assume a more circular shape.


Discussion

This study shows that the outcome of percutaneousballoon dilatation of the mitral valve is most closelyassociated with echocardiographic characteristics ofmitral valve structure. The mean values for theoptimal and suboptimal outcome groups showed thatthere were significant differences in the degree ofleaflet mobility, valvar and subvalvar thickening, andvalve calcification between the two groups. For eachof these variables, the greater the degree of leafletdeformity, the greater was the likelihood of a sub-optimal outcome, and, conversely, valves with a morenormal structure tended to be associated with anoptimal outcome (fig 5). This observation, that thestructure of the mitral apparatus is a major determi-nant of outcome in balloon dilatation of the mitralvalve, is consistent with previous experience withsurgical valvotomy. As early as 1953, Sellors et alsuggested that the type of mitral stenosis was themajor determinant of the success of closed surgicalcommissurotomy." Their careful analysis of thephysical signs related to a "pliant diaphragmaticvalve" is the clinical forerunner of our ownechocardiographic observations on leaflet mobility.Subsequent studies have confirmed that the mobilityof the valve leaflets determined at operation"2 and thedegree of fibrosis and calcification,'115 are the majordeterminants of both the short term and long termresults of closed mitral commissurotomy. Indeed,the poor results obtained in those patients withevidence of advanced valvar and subvalvar diseasehave led to the common practice of open mitralcommissurotomy on cardiopulmonary bypass, whenthe leaflets can be more directly inspected andincised."3Although the primary structural feature that

determines the haemodynamic severity of mitralstenosis is the mitral valve orifice area, the size of theorifice was in no way predictive of the outcome.Patients with small initial valve areas over the rangestudied were just as likely to have an optimal result asthose with larger valve areas before the procedure.This finding is somewhat surprising since we wouldhave expected the valve with the smallest areas tohave the most associated deformity and thus a poorerresult. This finding may relate to the highly selectedpatient group, since only those with critical diseasewere initially felt to be suitable for this newprocedure. Since most valve areas were in the rangeof0 4-1 -0 CM2 it might be difficult reliably to separateout the effects of initial valve area upon the outcome.This consideration is important, however, becauseour results suggest that this procedure may beapplied to patients with less severe mitral stenosis(larger valve areas) and at an earlier stage in the

on Novem



/B


ctober 1988. Dow

nloaded from



natural history of their disease, when the leaflets areless thickened and more mobile. As this groupincreases, valve area may also prove to be a predictorof outcome.

Several clinical factors, other than the echo-cardiographic variables, were also related to anoptimal outcome. These factors were the presence ofa lowerNew York Heart Association functional class,and a lower fluoroscopic grade of calcification. Theinitial haemodynamic variables that we measured(pre-dilatation transmitral gradient, cardiac output,and pulmonary artery pressure and resistance) werenot related to immediate outcome in this group ofpatients. These findings are also consistent withprevious surgical results after commissurotomy.""5A simple comparison of mean values in our study

shows that both echocardiographic and clinical fac-tors distinguished between the optimal and sub-optimal outcome groups. Since this analysis does notdetermine the most important variable or combina-tion ofvariables thatmay predict outcome, a multiplelogistic regression analysis was performed to weighthe significance of each of these factors. Thisapproach showed the single most important factorthat could be related to outcome was the totalechocardiographic score, which expressed the com-bined assessment of leaflet mobility, valvar andsubvalvar thickening, and leaflet calcification. Withthis score we were able to assess differing degrees ofleaflet immobility, deformity, and scarring. Allpatients with a total echocardiographic score > 11had a suboptimal result while all those with a score< 9 had an optimal result. The score failed to predictoutcome in those with scores of 9 to 11 (fig 5). Of theechocardiographic variables, no single factor, such assubvalvar thickening or valvar mobility alone, couldbe separated from the other structural features as asignificant determinant of outcome. The addition ofhaemodynamic or clinical variables or both,individually or in combination, also failed to improvethe logistic fit. Thus although outcome in this groupof patients is associated both with echocardiographicand clinical variables it is best predicted by theechocardiographic score alone.The effective dilating area of the balloon was not a

significant predictor of outcome. Clearly, a muchgreater dilating area can be achieved with the use ofadouble balloon technique, such as that described byAl Zaibag et al4 and Palacios et al.' This series,representing our earlier experience, contains onlyfour patients in whom we used a double balloontechnique. Nevertheless, we saw a trend towards abetter result. We therefore believe that the effectivedilating area of the balloon would have emerged as asignificant determinant of outcome7 had morepatients with a double balloon procedure been

307

included in the analysis.Finally, balloon dilatation of the mitral valve

seemed reliably to result in splitting of the mitralcommissures and not in traumatic avulsion ordamage to the leaflet bodies. Since the inflation of afluid-filled balloon within the confines of a smallorifice results in equal pressure being applied to allpoints on the surface, separation of the valve alongthe plane of least resistance (that is the commissures)is to be expected (fig 6).

LIMITATIONS OF THE STUDYThe echocardiographic analysis presented in thisreport is based on a qualitative assessment of themitral valve and apparatus. Although a more objec-tive method ofassessment may be desirable, it shouldbe remembered that when surgeons or pathologistsare able to handle the mitral valve they still describeany structural deformities in a qualitative mannerbecause there are no accepted objective measures ofmobility, thickening, or subvalvar thickening.Indeed it could be argued that because cross sectionalechocardiography provides an assessment of thesefeatures (particularly mobility) in the beating heart itis better than examination during cardiopulmonarybypass or at necropsy. The simplicity ofthe approachthat we have described should make it a practicalclinical method of assessing patients before balloondilatation of the mitral valve.With a qualitative method there may be differences

between observers in the assessment of the degree ofmitral mobility, valvar and subvalvar thickening, andvalve calcification. None the less, the interobserverand intraobserver variability for experiencedobservers was acceptably low. The accuracy of theassessment ofstructure also depends on the quality ofthe echocardiographic images obtained. The patho-physiology of mitral stenosis, with secondary rightventricular and biatrial enlargement, facilitatesechocardiographic imaging and visualisation of themitral valve. Moreover, none of the patients in ourseries was excluded because we could not adequatelyassess mitral valve structure by echocardiography.

CONCLUSIONThis study shows that the outcome of percutaneousballoon dilatation of the mitral valve is related to thestructure of the mitral valve and the subvalvarapparatus. Simple criteria obtained non-invasivelycan predict the likelihood of success of the procedureand hence may be used to select suitable patients.Since the 9iost favourable early results were seen inpatients with the least advanced valve deformity andscarring, this study implies that the procedure ismost successful in this group and should be perfor-

on Novem



/B


ctober 1988. Dow

nloaded from


308 Wilkins, Weyman, Abascal, Block, Palaciosmed before advanced scarring and immobility haveoccurred.

We thank John Newell for statistical guidance,Nancy Kriebel for preparing figures, and Drs JamesD Thomas, Christopher Y Choong, and John PO'Shea for advice.GTW was supported in part by the Odlin Fellow-

ship ofthe Royal Australasian College of Physicians,Wellington, New Zealand.

References

1 Lock JE, Khalilullah M, Shrivasta S, Bahl V, Keane JF.Percutaneous catheter commissurotomy in rheumaticmitral stenosis. NEngl J Med 1985;313:1515-8.

2 Palacios I, Lock JE, Keane JF, Block PC. Percutaneoustransvenous balloon valvotomy in a patient withsevere calcific mitral stenosis. J Am Coll Cardiol1986;7:1416-9.

3 McKay RG, Lock JE, Keane JF, Safian RD, AroestyJM, Grossman W. Percutaneous mitral valvotomy inan adult patient with calcific rheumatic mitral sten-osis. J Am Coll Cardiol 1986;7:1410-5.

4 Al-Zaibag M, Ribeiro PA, Al-Kasab S, Al-Fagih MR.Percutaneous double balloon mitral valvotomy forrheumatic mitral valve stenosis. Lancet 1986;i:757-61.

5 Babic UU, Peicic P, Djurisic Z, Vucinic M, Grujicic S.Percutaneous transarterial balloon valvuloplasty formitral valve stenosis. Am J Cardiol 1986;57:1101-4.

6 Kveselis DA, Rocchini AP, Beeklnan R, et al. Balloonangioplasty for congenital and rheumatic mitral sten-osis. Am J Cardiol 1986;57:348-50.

7 Palacios I, Block PC, Brandi S, et al. Percutaneousballoon valvotomy for patients with severe mitralstenosis. Circulation 1987;75:778-84.

8 McKay -RG, Lock JE, Safian RD, et al. Balloondilatation of mitral stenosis in adult patients: post-mortem and percutaneous mitral valvuloplastystudies. JAm Coil Cardiol 1987;9:723-33.

9 Inoue K, Owaki T, Nakamura T, Kitamura F,Miyamoto N. Clinical application of transvenous

mitral conumissurotomy by a new balloon catheter. JThorac Cardiovasc Surg 1984;87:394-402.

10 Harken DE, Ellis LB, Ware PF, Norman LR. Thesurgical treatment of mitral stenosis. N Engl J Med1948239:801-9.

11 Sellors TH, Bedford DE, Somerville W. Valvotomy inthe treatment of mitral stenosis. Br Med J 1953:ii:1059-67.

12 Hoeksema TK, Wallace RB, Kirklin JW. Closed mitralcommissurotomy; recent results in 291 cases. Am JCardiol 1966;17:825-8.

13 Grantham RN, Daggett WM, Cosimi AB, et al. Trans-ventricular mitral valvulotomy: analysis of factorsinfluencing operative and late results. Circulation1973;49(suppl II):203-1 1.

14 Ellis LB, Singh JB, Morales DD, Harken DE. Fifteento twenty-year study of one thousand patientsundergoing closed mitral valvuloplasty. Circulation1973;48:357-64.

15 Morrow AG, Braunwald NS. Transventricular mitralcommissurotomy. Surgery 1963;54:463-70.

16 Wann LS, Weyman AE, Feigenbaum H, et al. Deter-mination of mitral valve area by cross-sectionalechocardiography. Ann Intern Med 1978;88:337-41.

17 Henry WL, Griffith JM, Michaelis LL, McIntosh CL.Morrow AG, Epstein SE. Measurements of mitralorifice area in patients with mitral valve disease byreal-time, two-dimensional echocardiography. Cir-culation 1979;51:827-31.

18 Abbasi AS, Allen MW, DeCristofaro D, Ungaro I.Detection and estimation of the degree of mitralregurgitation by ranged gated pulsed Dopplerechocardiography. Circulation 1980;61:143-7.

19 Cohen MV, Gorlin R. Modified orifice equation for thecalculation of mitral valve area. Am J Cardiol1972;84:839-43.

20 BMDP statistical software. Department of Bio-mathematics, University of California, Los Angeles.Berkeley, California: University of California Press,1981.

21 Triulzi M, Gillam LD, Gentile F, Newell JB, WeymanAE. Normal adult cross-sectional echocardiographicvalues. Linear dimensions and chamber areas.Echocardiography 1984;4:403-26. on N

ovember 29, 2021 by guest. P

rotected by copyright.http://heart.bm

j.com/

Br H

eart J: first published as 10.1136/hrt.60.4.299 on 1 October 1988. D

ownloaded from


percutaneous dilatation valve - heart

Documents