Innovations in the Treatment of Valvular Disease — Successful Inoue Balloon Valvotomy in a Difficult Case of Mitral Stenosis Usi

Balloon mitral commissurotomy (BMC) using the Inoue balloon catheter is now an established mode of therapy for suitable cases of mitral stenosis with results comparable to closed as well as open surgical commissurotomy.1–3 With growing experience, increasingly complex cases are being effectively treated with this method using, at times, modifications in technique.4–7 Case Report. A 35-year-old woman (height, 164 cm; weight, 48 kg) with symptomatic severe mitral stenosis was evaluated for undergoing BMC. Echocardiography revealed non-calcific mitral stenosis (valve area, 0.8 cm2) without significant subvalvular pathology and no left atrial thrombus. The left atrium was enlarged (M-mode dimension, 60 mm). The right atrium and right ventricle were normal in size. Unusually, the inter-atrial septum was markedly bulging to the right not only in its central portion (as is commonly seen) but also through most of its extent. Therefore, almost the entire length of the septum was close and parallel to the right atrial free wall, leaving only a narrow space between the two. Although this anatomy was unfavorable for transseptal puncture, the patient was taken up for BMC with a plan to use the technique of retrograde non-transseptal balloon mitral valvotomy in case transseptal puncture failed.8 Right and left heart catheterization was performed via the femoral route to record the baseline data (mitral valve area, 0.8 cm2; mean diastolic gradient (MDG), 18 mmHg; BDG, 14 mmHg; mean pulmonary artery wedge pressure, 22 mmHg; mean pulmonary artery pressure, 36 mmHg; mean right atrial pressure, 4 mmHg). There was no mitral regurgitation on left ventricular angiography in the 30° right anterior oblique view. Transseptal puncture was difficult due to the unusual septal anatomy; despite several attempts using different clock positions and shapes of the transseptal needle, it could not be optimally positioned. The transseptal needle could be maneuvered to a position perpendicular to the inter-atrial septum only in its most caudal portion and puncture had to be performed at this unfavorable site, traversing the thick muscular part of the inter-atrial septum. Subsequently, as anticipated, difficulty was encountered in crossing the mitral valve. During attempts to bring the tip of the balloon catheter close to the mitral orifice, the proximal part of the balloon was repeatedly getting stuck in the inter-atrial septum since the puncture site was too close to the mitral valve orifice. Trials to cross the mitral valve with guidewires passed through the central lumen of the balloon catheter were unsuccessful. It was then decided to form the Inoue balloon catheter into a loop to cross the valve, since this would keep the balloon free from the septum. Due to the unusual location and orientation of the balloon catheter in the left atrium, this could not be easily achieved with the standard method described for loop formation.5 Therefore, it was decided to attempt an alternative method for forming the balloon catheter into a loop. The balloon catheter was positioned well into the left atrial cavity. The coiled Inoue wire was then introduced into the left atrium (as is usually done immediately after transseptal puncture) such that the coils of the wire lay on the left side of the balloon (Figure 1A). The wire was then rotated clockwise through approximately 180° with the help of a “torquer” device (which is routinely used during coronary angioplasty) to bring the coils of the wire to lie on the right side of the balloon. This rotation was combined with a slight withdrawal of the balloon catheter to stabilize the coils of the wire in the desired position (Figure 1B). The balloon could then be easily tracked over this wire until it formed a loop (Figure 1C), at which point the Inoue wire was removed (Figure 1D). However, even with a loop, crossing the mitral valve was not possible either with the balloon alone (even with partial inflation) or with the help of the J stylet. Therefore, the mitral valve was crossed with a 0.032´´ straight-tip guidewire (shaped into a wide distal curve) passed through the central lumen of the balloon catheter. The balloon was then partially inflated and tracked over this wire (Figure 2) to dilate the mitral valve (balloon size, 24 mm). After dilatation, there was no residual end diastolic gradient, the MDG was 4 mmHg, mean wedge pressure was 10 mmHg and the mitral valve area was 2.2 cm2. A repeat left ventricular angiogram showed no mitral regurgitation. Discussion. Balloon mitral commissurotomy using the Inoue balloon is a relatively simple and invariably successful procedure in typical cases of mitral stenosis with a favorable cardiac anatomy. However, in high-volume centers such as ours, performing over 800 BMC procedures annually, it is common to encounter complex cases of mitral stenosis such as those with large atria, bulging or rotated inter-atrial septum, systemic or suprasystemic pulmonary artery pressures, severe subvalvular pathology and restenosis after surgical commissurotomy.9,10 Although surgical commissurotomy is an alternative in such cases, in high-volume centers with a negligible risk of tamponade, BMC is still the more favored therapeutic option by virtue of being non-surgical and cosmetically acceptable. At times, such cases require the use of modifications in the standard BMC technique6 or the retrograde non-transseptal technique.11 Recently, a transjugular approach has also been used to perform BMC in cases with distorted atrial anatomy.12 In our case, transseptal puncture had to be inevitably performed at an unfavorable site due to the grossly distorted atrial and septal anatomy. The utility of atrial angiography and echocardiographic guidance is limited in such cases because the problem is not so much identifying the conventionally correct site of puncture as it is aligning the transseptal needle perpendicular to the septum at this site. The ensuing difficulty in crossing the mitral valve and the problem of septal balloon entrapment during attempts to cross the valve were overcome by the synergistic use of two different modifications — formation of the balloon catheter into a loop by a new method and use of the guidewire for entering the left ventricle. Using a guidewire to cross the mitral valve may result in passage of the wire through the chordal structures, but this could be reasonably excluded by advancing the Inoue balloon over the wire after partial inflation of the balloon as was done in this case. Although we did not have difficulty in tracking the balloon catheter over an ordinary 0.032´´ guidewire, it may be preferable to electively use a 0.032´´ extra-stiff wire with a wide distal loop for crossing the mitral valve so that better support is provided for advancing the balloon catheter. Our case illustrates the following points: 1) In selected difficult cases of BMC, a synergistic combination of several modifications of technique may be required. The combined use of the “loop technique” and “over-the-wire” entry into the left ventricle may prove successful in some of these cases when conventional methods fail. 2) The “Inoue wire” method of forming the Inoue balloon into a loop described in the present report is a simple alternative to the hitherto practiced “stylet” method.5 This method scores over the conventional stylet method in its simplicity but necessitates change of the J stylet to the Inoue wire, unless the loop technique is performed electively. Furthermore, kinking and blockade of the central balloon lumen that sometimes occur with the stylet method following difficult or repeated (when several inflations need to be made) loop formation would not occur with our method. Although the described method may be cumbersome when the mitral valve needs to be crossed more than once for multiple inflations, our experience indicates that subsequent crossings by the loop method become easier after the valve has been dilated once. Alternatively, when multiple inflations need to be made, the Inoue balloon catheter could be advanced to the apex of the left ventricle after deflation. The adequacy of dilatation could then be assessed using the pulmonary artery wedge pressure (instead of the left atrial pressure) recorded by a Swan-Ganz catheter introduced from the left groin as is routinely done by some operators.

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