Evaluation of a Simplified Transseptal Mitral Valvuloplasty Technique Using Over-the-Wire Single Balloons and Complementary Femo

Balloon mitral valvuloplasty (BMV) is an effective method for treating rheumatic mitral valve stenosis, producing good short- and long-term results^1–2 that are comparable to surgical valvotomy.^3–4 Two BMV techniques have been extensively used: the Inoue balloon technique,⁵ and the transseptal over-the-wire balloon technique,^6–12 the latter of which predominantly uses double balloons (DBT). The DBT has been decreasingly used in recent years because of several limitations (Table 1), the most significant being its relative complexity and potential for left ventricular perforation.¹³ Another limitation common to all transseptal techniques is that the procedure can be difficult or unsuccessful in situations where there is gross distortion of the cardiac anatomy.^14–16 We attempted to make transseptal over-the-wire BMV simpler and safer by developing and evaluating a single balloon technique (SBT) of BMV at our center, drawing on earlier experience with DBT17 and with an alternative jugular approach to BMV.¹⁸ Methods and Patients Patients with rheumatic mitral valve stenosis and valve area 2 were selected for BMV if they did not have severe mitral regurgitation, evidence of left atrial thrombus outside the left atrial appendage, or a highly deformed mitral valve. Written informed consent was obtained from all patients. The institutional review board approved this study. Echocardiography. Echocardiography was performed before and 24 hours after BMV. Patients with atrial fibrillation also underwent transesophageal echocardiography. Mitral valve morphology was scored,¹⁹ mitral regurgitation was graded,²⁰ and mitral valve area was determined by using continuous wave Doppler and two-dimensional planimetry. Echocardiographic guidance was not utilized during the BMV procedure. Valvuloplasty balloon. We developed a simple over-the-wire mitral valvuloplasty balloon catheter (Jomiva,™ Numed, Hopkinton, New York), by modification of a pre-existing balloon-catheter (Nucleus,™ Numed, inc.). The Jomiva balloon (Figure 1) is cylindrical, expands to a fixed size, has two radio-opaque markers corresponding to a 4 cm working length, and is made of thin thermoplastic polymer that gives large diameter balloons a low crossing profile. The design includes an abrupt distal balloon taper and a short, blunt catheter tip to prevent left ventricular perforation. The catheter shaft (9 Fr for smaller balloons, 11 Fr for larger balloons) has a coaxial construction that allows for short balloon inflation-deflation times (Valvuloplasty technique. BMV procedures were performed under antibiotic cover (cefazolin), using local anesthesia. Five-thousand units of heparin were administered intravenously after completion of the septal puncture. Right heart catheterization preceded BMV, and was repeated, along with oximetry which was run after BMV. Femoral venous approach was the predominant route used in SBT-BMV, and was applied to the entire spectrum of patients undergoing BMV; the alternative jugular approach was limited to patients with features of cardiac anatomic distortion (marked left atrial enlargement or rightward septal bulge, cardiac rotation or displacement due to adhesions from previous surgery, and dextrocardia), failed femoral approach, and venous abnormalities.¹⁶ Crossovers from the femoral to the jugular approach, or vice-versa, were classified under the second approach used. Femoral approach. Right femoral arterial and venous accesses were obtained and transseptal puncture performed at the fossa ovalis using standard equipment and technique.²¹ The mitral valve was crossed using a balloon floatation catheter. The J-tip of a 0.035 inch valvuloplasty guidewire (Back-up Meier,™ Boston Scientific, Natick, Massachusetts) was positioned at the left ventricular apex after manually shaping the stiff shaft just proximal to its soft distal portion into a wide secondary curve. Care was taken during guidewire introduction into the left ventricle to ensure that the tip of the floatation catheter did not abut the ventricular wall, and to ensure that the guidewire tip curled freely as it emerged from the catheter. The Jomiva balloon was introduced through a 50 cm long, 12–14 Fr valved left atrial sheath (Cook, Bloomington, Indiana), and valvuloplasty was performed (Figure 2A) after withdrawing the sheath into the inferior vena cava to allow a more transverse and stable lie of balloon and guidewire across the mitral valve. Jugular approach. Right internal jugular venous and right radial arterial accesses were obtained, and pulmonary angiography was performed in a 45° right anterior oblique view to acquire a levophase image of the left atrium.^16,18 Transjugular septal puncture was performed in the same view using an Endrys pediatric transseptal set (Cook). The atrial septum was punctured above the fossa ovalis about 2 cm (a vertebral body height) below the roof of the left atrium, and midway between the aorta and the anterior border of the spine. Bulging of the atrial septum toward the right facilitates obtaining a catch with the needle prior to puncture at the desired location on the septum. A 14 Fr, 20 cm long, J-shaped sheath with haemostatic valve was inserted into the left atrium, and the mitral valve was crossed using a balloon-floatation catheter. A 0.035 inch Amplatz wire with a large soft J-tip (Cook) was placed in the left ventricular apex, and valvuloplasty was performed after introducing a Jomiva balloon through the left atrial sheath (Figure 2B). Balloon sizing. The method of balloon sizing in SBT-BMV was similar to that used in Inoue-balloon BMV,²² and was based on body height. The initial balloon used was usually 2–4 mm smaller than the reference size for the patient; progressively larger balloons were used if additional dilatation was required. In DBT-BMV, the effective balloon diameter was taken to be that of a hypothetical single balloon having the same perimeter as the two balloons combined.²³ Smaller effective balloon diameters were used in SBT-BMV when compared to those used earlier in DBT-BMV in order to minimize the incidence of post-BMV mitral regurgitation. Statistical methods. Data for all cases were collected prospectively and analyzed using SPSS software. Analysis of variance and the chi-square test were used to compare variables in different patient subgroups. Pearson’s coefficient was used to determine correlations between variables. Multivariate linear regression analysis was performed to identify determinants of post-BMV mitral valve area. P-values Baseline patient characteristics. We performed 2,361 over-the-wire BMV procedures over 14 years: 954 DBT from 1990 to 1997, and 1,407 SBT from 1997 to 2003. Baseline demographic and clinical features of the patients are presented in Table 2. Pre- and post-1997 patients differed in several respects, reflecting changes in disease and referral patterns over 14 years; post-1997 patients were older and had a less favorable anatomy, but underwent BMV at an earlier functional stage. These differences, though mostly small in magnitude, were statistically significant because of the large number of patients involved. Within the SBT group, the jugular approach patients had significantly larger mean left atrial size (56 ± 8 mm versus 47 ± 7 mm), and more frequent atrial fibrillation (53% versus 15%) and previous surgical valvotomy (23% versus 11%) compared to the femoral approach patients (p = 0.000 for each comparison). Conversely, however, patients with left atrial size >= 60 mm were almost equally distributed between the femoral (49%) and jugular (51%) SBT subgroups. Procedure outcome. The outcome of BMV (Table 3) was classified into four categories: 1) optimal (post-BMV mitral valve area >= 1.5 cm²); 2) suboptimal (valve area 2); 3) incomplete procedure; and 4) major complication (irrespective of valve area). SBT-BMV resulted in a significantly higher proportion of optimal outcomes and significantly lower proportions of incomplete procedures and major complications when compared to DBT-BMV. The jugular SBT patients had a lower proportion of optimal outcomes and higher proportions of other outcomes compared to the femoral SBT patients. Mitral valve area. Both BMV techniques produced significant increases in mitral valve area, though the mean area obtained with DBT-BMV was significantly larger (Table 3). In a 20-variable linear regression model, post-BMV mitral valve area was directly related to the effective balloon diameter (standardized coefficient b = +0.391, p = 0.000), baseline mitral valve area (b = +0.147, p = 0.000) and DBT-BMV (b = +0.115, p = 0.032), and inversely related to the left atrial size (b = -0.119, p = 0.000), mitral valve morphologic score (b = -0.085, p = 0.001), and previous surgical valvotomy (b = -0.083, p = 0.000). Variables not significantly influencing post-BMV mitral valve area in the multivariate model were age, sex, body surface area, duration and class of symptoms, cardiac rhythm, pulmonary artery and left atrial mean pressures, transmitral gradient, baseline mitral regurgitation grade, tricuspid regurgitation grade, previous balloon valvuloplasty, mitral valve to apex distance, and pregnancy. Jugular SBT patients had smaller pre- and post-BMV mitral valve areas compared to femoral SBT patients. Fluoroscopy time. The total fluoroscopy time required was significantly lower in SBT-BMV compared to DBT-BMV (Table 3). Jugular SBT patients required significantly less fluoroscopy time compared to femoral SBT patients (p = 0.000), despite the jugular subgroup being selected on the basis of cardiac anatomic distortion. A significant direct correlation was seen between left atrial size and fluoroscopy time in the femoral SBT subgroup (r = +0.116, p = 0.000), whereas a significant inverse correlation was seen between these two parameters in the jugular SBT subgroup (r = -0.190, p = 0.036). Hemodynamics. Hemodynamic parameters improved significantly with both BMV techniques (Table 4); they were slightly more deranged in SBT patients compared to DBT patients before and after BMV. The jugular SBT patients had more deranged hemodynamic parameters before and after BMV than did the femoral SBT patients. Oximetry. Significant right heart oxygen step-up after BMV was seen more frequently with DBT-BMV, which requires septal dilatation using an 8 mm balloon (Table 4). The incidence of significant right heart oxygen step-up was lower in jugular SBT-BMV (where thick atrial septum was punctured and balloon removal was via a left atrial sheath that protected the septum from folds of the balloon), than in femoral SBT-BMV (where the balloon was removed bare through thin atrial septum). Complications. Comparatively lower complication rates with SBT-BMV (Tables 3 and 5) were largely related to DBT being used in the early stages of the BMV program when most operators went through their learning curve; when the learning phase was excluded by considering the last 500 DBT cases only, complication rates in the two groups were more comparable, and not statistically different. There were no instances of left ventricular perforation in the last 582 cases of SBT-BMV; the two instances seen earlier were related to guidewire introduction and were not balloon-related. There were no mechanical problems with the Jomiva balloon such as failure to deflate or embolization of balloon material. Balloon usage. A mean of 1.31 ± 0.50 Jomiva balloons (range 1 to 3) were used per patient in SBT-BMV (average local cost $519), whereas two conventional valvuloplasty balloons and one angioplasty balloon were required per patient in DBT-BMV ($1,167). Discussion Since the inception of BMV,^5,6 several efforts have been made to improve BMV equipment and technique,^{7–12,15,18,24–26} which reflect limitations in existing BMV techniques. The single balloon technique of BMV that was developed and evaluated in this study was successful in overcoming the limitations of over-the-wire transseptal BMV techniques listed in Table 1, while preserving or improving efficacy and safety. Salient features of the study were: (a) evaluation of SBT-BMV in a large number of patients; (b) consecutive selection of cases over the entire 7-year study period; (c) use of the jugular approach in patients with distorted cardiac anatomy –– this is the first definitive case series involving the jugular approach for over-the-wire BMV. Efficacy. The efficacy of SBT-BMV was comparable to that of DBT-BMV; SBT-BMV had a higher proportion of optimal outcomes, whereas mean post-BMV mitral valve area and hemodynamic parameters were slightly inferior to those obtained in DBT-BMV. Multivariate analysis revealed that the relatively smaller post-BMV mitral valve area obtained with SBT-BMV was mainly due to three independent factors: 1) Smaller balloon diameters were used in SBT-BMVin order to minimize the incidence of severe mitral regurgitation; 2) baseline patient characteristics in the SBT group (left atrial size, mitral valve morphologic score, and previous surgical valvotomy) were less favorable than in the DBT group –– such temporal trends have been noted by other workers;²⁷ 3) the double balloon technique itself was a significant determinant of higher post-BMV mitral valve area, which is consistent with studies comparing DBT-BMV with BMV using single Inoue balloons.^28–30 Within the SBT group, the jugular approach patients had slightly inferior results compared to the femoral approach patients with respect to valve area, outcome, and hemodynamics; this is consistent with the more advanced disease present in these patients. Safety. The rates of each type of complication with SBT-BMV were comparable to or lower than those seen with DBT-BMV. Balloon-induced left ventricular perforation did not occur with SBT-BMV, attesting to the safety of balloons with short, blunt tips and abrupt distal taper. Instances of left ventricular perforation by the valvuloplasty guidewire have not recurred after adopting the earlier described safe technique of guidewire introduction into the left ventricle. Procedural ease. The significantly shorter fluoroscopy time and lower incidence of incomplete procedures with SBT, when compared to DBT, reflect the simplicity of this technique. Within the SBT group, selection of patients with cardiac anatomic distortion for the jugular approach may have indirectly improved results in the femoral approach group; even shorter fluoroscopy times and a low incidence of incomplete procedures with the jugular approach indicates that this approach is well suited for patients with distorted anatomy. The opposite relationships between left atrial size and fluoroscopy time seen in the two approaches indicate that the larger the left atrium, the more difficult the femoral approach, and the easier the jugular approach. The femoral and jugular approaches for BMV thus complement each other well; each approach can be used electively in appropriate situations, and as a bail-out for the other approach when an unexpected difficulty arises. The use of long left atrial sheaths for the introduction of mitral valvuloplasty balloons has been reported earlier.²⁶ Such sheaths facilitate movement of the valvuloplasty balloon across resistance points at the skin puncture site and at the atrial septum, and obviate the need to predilate these points. If these sheaths have a curved tip they can also help guide the balloon through the mitral valve, stabilize the balloon during inflation, and allow left atrial pressure recording throughout the procedure; the jugular sheath used in this study had a curved tip and therefore allowed these functions, whereas the femoral sheath used was straight and relatively stiff, and had to be withdrawn into the inferior vena cava after balloon introduction into the left atrium. Economy. Use of single balloons and the Jomiva balloon catheter’s simple design and relatively inexpensive material components (which reduced manufacturing costs), helped lower SBT balloon costs to approximately half of that for DBT. SBT procedure costs were further reduced by the need for only one valvuloplasty guidewire (compared to two in DBT), and indirectly through lower rates of complications and incomplete procedures. Though not considered in the cost analysis, multiple reuse of the Jomiva balloon was safely possible after ethylene oxide gas resterilization, which further reduced SBT balloon costs several-fold. Applicability. Use of SBT as the only BMV technique at our center for seven years in 1,407 consecutive patients with wide ranging characteristics, attests to its applicability to all patients requiring BMV. SBT-BMV is especially suited to large-volume centers in developing countries where cost considerations can be overriding. Operators familiar with DBT found that femoral approach SBT was technically less demanding and could easily switch to SBT. The less frequently needed jugular approach requires different skills, and is therefore more appropriate for high-volume operators. Study limitations. Comparison of SBT-BMV with DBT-BMV performed during the preceding seven years at the same center was limited by the fact that comparison between the two groups was not randomized, operators were less experienced during the earlier period, and patient characteristics changed marginally over time. Nevertheless, the earlier experience with DBT-BMV provided a useful standard against which SBT-BMV could be compared, considering that (a) conventional DBT is one of two major BMV techniques that have had the widest application and has remained unchanged over the last decade; (b) DBT cases used for comparison in this study came from the same center, were performed by the same operators, and were drawn from the same referral population base; (c) the DBT series was large (954 cases) and went well past the early learning phase; (d) the last 500 cases of DBT-BMV were separately analyzed with regard to complications to exclude the early learning phase. Another limitation of this study is that SBT-BMV was not compared with the more popular Inoue technique because very few cases were performed using the latter technique due to the high cost of the Inoue balloon. However, the SBT results compare favorably with published results of trials with the Inoue balloon from different parts of the world (Table 6). Conclusion SBT-BMV using Jomiva balloons and complementary femoral and jugular venous approaches was effective, safe, technically simple, and economical. It was comparable to and overcame several limitations of DBT-BMV.

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