Percutaneous Mitral Commissurotomy in a Case of Mirror-Image
Dextrocardia and Rheumatic Mitral Stenosis

Distorted cardiac anatomy offers technical difficulties during fluoroscopy-guided transcatheter procedures. This is even more the case with percutaneous transvenous mitral commissurotomy (PTMC), where the cardiac malpositions considerably increase the complications involved in interatrial septal puncture and left ventricular entry. Though it has been established as the procedure of choice in a selected subset of patients with rheumatic mitral stenosis (MS), there are only a few reports on successful PTMC in altered cardiac anatomy using the standard Inoue technique.^1–6 Here we describe a case of a 43-year-old male with situs inversus and dextrocardia, where PTMC was successfully performed with a few modifications of the standard Inoue technique previously described in similar settings. Particular emphasis is given on the measures taken for optimal performance of transseptal puncture in this patient.

Case Report. A 43-year-old male with a history of rheumatic fever in childhood presented with dyspnea on exertion of (NYHA class II) 6 months’ duration. Clinical and echocardiographic evaluation suggested situs inversus, dextrocardia and severe rheumatic MS. His mitral valve area (MVA) was 0.8 cm² with bicommissural fusion and moderate subvalvular pathology. The interatrial septum (IAS) showed an atrial septal aneurysm, and the rest of the IAS bulging into the right atrium. PTMC was planned, and the preprocedural transesophageal echocardiogram (TEE) ruled out left atrial thrombus.
Femoral arterial and venous punctures were made on the left side. Right heart catheterization was performed, showing mild pulmonary hypertension. Next, fluoroscopic imaging was inverted left-to-right by built-in software in the radiographic system (Philips Medical Systems, Andover, Massachusetts). This created a pseudo-AP view when the C-arm was in the AP position and a pseudo-right anterior oblique (RAO) 30^º view when the C-arm was in left anterior oblique (LAO) 30^º view. Pulmonary angiography was performed in the pseudo-AP and lateral views with the inverted settings, and the IAS and its relation to the noncoronary aortic sinus were delineated in levophase. Next, septal descent was performed in the pseudo-AP view with the needle kept in the 7 o’clock position. After achieving the standard fluoroscopic positions in pseudo-RAO, pseudo-AP and lateral views, the septum, along with the interatrial septal aneurysm, were stained with contrast injection into the septum. The septum was probed for entry into the left atrium (LA) through a patent foramen ovale, but was unsuccessful. A 6 Fr pigtail catheter was placed in the noncoronary aortic sinus and the septal puncture was done in a lateral view. Then, 2,500 IU of intravenous heparin was administered and the pressure gradient between the LA and left ventricle (LV) was noted. The IAS was dilated with a septal dilator and a 28 mm Accure balloon was tracked over the Inoue wire to the LA. Left ventricular entry was attempted with a stylet to the tip of the balloon followed by clockwise rotation in the LA in a pseudo-RAO view. A small calcific speck at the anterolateral commissure also marked the mitral valve fluoroscopically. However, the LV could not be entered despite multiple attempts using this standard method. Next, a reverse-loop technique was tried and the balloon entered the LV on the first attempt. Graded inflations were done at 24 and 25 mm. The LA pressure fell from 24 mm to 11 mmHg, with no residual gradient across the mitral valve. Echocardiography showed a well-divided lateral commissure with a MVA of 1.8 cm² and no mitral regurgitation. At 6-month of follow up, the patient continued to remain in NYHA class I.

Discussion. Mirror-image dextrocardia, as in our case, has been estimated to occur with a prevalence of 1:10,000 patients. In geographical areas with a high prevalence of rheumatic heart disease, the coincidence of rheumatic MS and dextrocardia is a chance occurrence. However, there are only a few case reportsin the literature on PTMC in similar settings.^1–6 This might be due to the fact that many of these patients undergo surgical commissurotomy due to the technical difficulties involved in a percutaneous procedure.^7,8 However, we decided to proceed with this technically demanding procedure in view of the significant experience we had with PTMC in the past.
In general, anatomical variations of the heart are considered as relative contraindications for transseptal catheterization, as it is fraught with a higher risk of cardiac perforation. Previous authors have employed various modifications to suit the abnormal anatomy in such patients.^1–5 Transseptal catheterization was performed from the left groin to reduce the puncture needle angulation at the confluence of the iliac veins to the left-sided inferior vena cava. Septal descent wasdone by rotating the external indicator of the needle at 120^º, i.e., the 7 o’clock position. The delineation of the IAS is the most important and difficult step in the procedure. Verma et al used levophase pulmonary angiography for IAS delineation in a patient with isolated dextrocardia and normal atrial situs.⁶ This step, which had not thus far been described in any patient with mirror-image dextrocardia undergoing PTMC, was considerably helpful to us in delineating the IAS fluoroscopically. The catheter placed in the noncoronary aortic sinus marked the antero-superior limit of the IAS also. We did not use TEE, as it requires mild sedation and is time-consuming. The radiographic images were acquired in the inverted position and were used as fluoroscopic guidance for the septal puncture, as previously described by Nallet et al.⁴ The inverted fluoroscopic settings, which simulated normal anatomy, facilitated manipulation of the transseptal needle and balloon in the LA. These modifications were supplemented by contrast injection into the septum to delineate the IAS, which was of additional use in the presence of the septal aneurysm in this patient. Septal staining delineated the septum well, though the septal aneurysm required multiple attempts at probing and septal puncture. The usefulness of intracardiac echocardiography (ICE) in preventing serious complications in transseptal procedures when the cardiac anatomy is unusual or distorted has also been highlighted recently.⁹ However, an ICE facility was not available to us at the time of PTMC in this patient.

It was difficult to maneuver the balloon into the LV, even with the necessary modification of standard technique consistent with the malposition in our case. However, with the reverse balloon technique, we were able to enter the LV on the first attempt. Previously, this technique had been recommended in low septal punctures and large left atria.¹⁰ This may also be a good alternative to the standard technique of left ventricular entry in cases of altered cardiac anatomy due to cardiac malpositions, as was evident in this case.
In summary, PTMC is feasible in the rare patient with situs inversus and dextrocardia with additional modifications of the Inoue technique to delineate the IAS. This case also highlights that the reverse-loop is an alternative technique for left ventricular entry in cases of cardiac malpositions.