Percutaneous Transvenous Mitral Commissurotomy Using Metallic Commissurotome: Long-Term Follow-Up Results

Percutaneous Transvenous Mitral Commissurotomy Using Metallic Commissurotome: Long-Term Follow-Up Results
Percutaneous Transvenous Mitral Commissurotomy Using Metallic Commissurotome: Long-Term Follow-Up Results

S. Harikrishnan, MD, Anil Bhat, MD, Jaganmohan Tharakan, MD, Thomas Titus, MD, Ajith Kumar, MD, S. Sivasankaran, MD, K.M. Krishnamoorthy, MD

Percutaneous transmitral commissurotomy (PTMC) has been established as an effective treatment for mitral stenosis (MS) and is now the procedure of choice.1–6 Of the procedures available to treat mitral stenosis, percutaneous valvotomy using the Inoue balloon is well established and carried out worldwide.
The miniaturized metallic commissurotome devised by Cribier et al. is reported to be a reliable and effective alternative to balloon mitral commissurotomy.7–11 The ease of resterilization and unchanged physical properties after multiple uses have made this device a promising alternative to balloon valvotomy, especially in developing countries that are forced, despite the inherent dangers, to reuse balloon catheters.
There are several reports of PTMC procedures using metallic commissurotomy describing the acute and short-term results.7–18 However, reports of long-term efficacy of this technique are very few with small numbers of patients.19 Here we report the long-term follow-up results of mitral valvotomy using the metallic commissurotome.

Materials and Methods
Study population. A total of 248 (65 males) patients, with severe mitral stenosis who underwent PTMC using the metallic commissurotome at our institution formed the study population.
Methods. Prior to the procedure, all patients underwent a detailed clinical and echocardiographic evaluation (2-D echocardiography, Doppler and color flow imaging) to assess the severity of mitral stenosis, valve morphology and mitral regurgitation (MR). The Wilkins echocardiographic scoring system20 in 16 grades was used to assess the severity of mitral valve thickness, leaflet mobility, valvular calcification and subvalvular disease, each being graded from 1 to 4. The mitral valve area was determined by 2-D echocardiography with planimetry in the parasternal short-axis view, and by continuous wave Doppler using the “pressure half-time” method.
Multiplane transesophageal echocardiography (TEE) was used in all adults to rule out left atrial (LA) clot and to assess MR. Patients < 20 years of age did not undergo TEE unless the suspicion of LA thrombus was high (dense left atrial spontaneous echocardiographic contrast or patient in atrial fibrillation). Transthoracic echocardiography was performed on all patients during PTMC, 24 hours after the procedure, and at follow-up visits.
The contraindications to the procedure, as assessed by echocardiography, were greater-than-mild MR, LA thrombus on TEE performed prior to PTMC, and extensive commissural calcification. PTMC was performed using the anterograde transseptal technique as already described.21 The procedure was performed under local anesthesia, with the entry site being the right femoral vein in all patients.
All procedures were performed with standby closed and open heart surgery capabilities. All patients were administered prophylactic antibiotics. Septal puncture was done via the Brockenbrough technique, and all patients were heparinized after septal dilatation. A lower septal puncture was preferred for this PMMC procedure.
Left ventricular (LV) angiography in the 30° right anterior oblique view was performed prior to the procedure in all patients suspected of having more than mild MR. Mitral regurgitation was graded 1 through 4, as already described.22 Patients who had more than mild MR were excluded. Immediately before and after PTMC, the left and right heart pressures and the mean transmitral pressure gradients (TMG) were measured. The result of the procedure and the amount of MR were assessed by echocardiography in the catheterization laboratory itself.
Procedural success was defined as an increase in mitral valve area of at least 50% from the basal, or a final valve area of > 1.5 cm2 in the absence of moderate-to-severe mitral regurgitation. Transatrial shunting was assessed after the procedure with oximetry run, and on follow-up with color flow imaging. Mitral restenosis was defined as a loss of > 50% initial gain in valve area with reappearance of symptoms.5
PTMC using metallic commissurotome (PMMC). Percutaneous metallic mitral commissurotomy was performed as previously reported.7,9,11 The metallic commissurotome (Medicorp, Inc., France) consists of a distal metallic head (5 cm long x 5 mm in diameter) comprised of two 15 mm long hemicylindrical bars. It is fixed at the tip of a 12 Fr disposable catheter and connected by an internal cable to a proximal hand-operated device that can open the arms gradually to a maximum of 40 mm. The metallic head is detachable and can be resterilized and reused multiple times.
After septal puncture, a Mullins sheath was introduced into the LV with the help of a 7 Fr balloon floatation catheter (Arrow International, Inc., Reading, Pennsylvania) across the mitral valve. A beaded stainless steel wire, 270 cm in length and 0.035 inch in size (with a metallic bead 2 mm in diameter soldered at the junction of the stiff core and the 10 cm distal floppy end), was positioned in the LV through the Mullins sheath. The commissurotome is tracked over the bead wire across the atrial septum and the mitral valve. The extent of the initial bar opening was selected based on the patient’s body surface area. Patients had the initial bar opening set at 33, 35 or 37 mm depending on their body surface area and, if necessary, the bar was increased gradually to a maximum of 40 mm.
Follow-up evaluation. Follow-up evaluations were completed at 1 month, 6 months and then yearly. The follow-up evaluation at 1 month included clinical examination only. At 6 months and at yearly follow-up visits, patients underwent a detailed clinical and echocardiographic evaluation. Patients who never came for regular follow-up and those who did not participate in the follow-up in the preceding 1 year after the procedure were contacted by letter and asked to report for review. Those who could not come for follow-up were asked to consult the local cardiologist and forward our institution the echocardiographic and clinical report so that the data could be used for analysis.
Statistical analysis. Continuous variables are expressed as mean ± SD and compared using the independent sample t-test, with 95% confidence interval. Categorical variables are compared with the Fisher’s exact test. A p-value < 0.05 was considered significant. Statistical analysis was done using SPSS for Windows, Version 10.0.

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