Misadventure during balloon mitral valvuloplasty, a complication despite all precautions

Accidental aortic puncture is a much dreaded and potentially serious complication of transseptal catheterization and was recognized in the initial description of the technique by J. Ross Jr and colleagues in 1958. However, inadvertent puncture of the pulmonary artery, although theoretically possible and despite the vast experience with transseptal balloon mitral valvuloplasty (BMV), has never been described. We present a unique case where BMV in a pregnant patient was complicated by puncture of the right main pulmonary artery (PA). We also discuss possible mechanisms and approach to management.

A 40-year-old grand multipara (G₉P₈L₈A₁) was referred to our institution for severe rheumatic mitral stenosis (MS). All her previous pregnancies were unremarkable. However, into the second trimester of her current pregnancy, she was becoming increasingly dyspneic at mild to moderate levels of physical exertion. At 18 weeks of gestation, a transthoracic echocardiogram revealed normal left ventricular (LV) dimensions and systolic function. The right ventricle (RV) was normal. The Left atrium (LA) was severely enlarged. The mitral valve (MV) was rheumatic and severely stenotic. The MV area (MVA) was measured at 1.4 cm² using the pressure half-time (PHT) method and 1.5 cm² on planimetry. The mean MV gradient was 12 mmHg at a sinus rate of 100 beats per minute. The Wilkin’s score was 7 out of 16 points. The pulmonary artery (PA) pressure was moderately elevated with an estimated PA systolic pressure (PASP) of 51 mmHg. The main and branch PA were dilated. She remained dyspneic despite furosemide and bisoprolol, and therefore, referred for balloon mitral valvuloplasty (BMV). At this time, she was past 30 weeks of gestation. A transesophageal echocardiogram (TEE) revealed a MVA of 1.4 cm² using the PHT method. The mean MV gradient had increased to 18 mmHg at a sinus rate of 110 beats per minute. She now had a moderately dilated RV with moderate to severe tricuspid regurgitation and severe pulmonary hypertension with an estimated PASP of 65 mmHg. Anticipating a difficult transseptal access, TEE was briefly used during the procedure to guide the transseptal puncture. The initial hemodynamic measurements are summarized in supplemental table S1. Transseptal puncture was attempted using a BRK needle (BRK Transseptal Needle, St. Jude’s Medical, Belgium) and an 8.5 Fr SL-0 sheath (Swartz SL-0, St. Jude’s Medical, Plymouth, USA). This proved quite challenging and after multiple attempts, the interatrial septum (IAS) was pierced in a more superior location. Upon connecting end of the BRK needle to a manometer, a PA arterial pressure tracing was obtained (Figure-1). This was confirmed with a gentle contrast injection though the tip of the dilator (Supplemental Video S1). A 0.032” guide wire was advanced through the dilator and appeared to course down the left main PA. No anticoagulation had been administered yet. Since the TEE probe had already been withdrawn, a bedside echocardiogram was performed and revealed a new small circumferential pericardial effusion without signs of tamponade. The dilator was slowly and gradually withdrawn back into the LA. Serial echocardiograms reassuringly confirmed stability of the effusion. Since the operators still had access to LA, a standard LA wire was secured in a double loop within the LA cavity (Supplemental Video S2). At this point, unfractionated heparin was administered. The effusion remained unchanged throughout the procedure. The mitral valve was then dilated with a 26-mm INUOE balloon (Toray INUOE balloon, Toray Industries, Tokyo, Japan) with a significant reduction in transvalvular gradient (Supplemental Table S1). After the procedure, the patient remained in the hospital for five days for monitoring. A detailed echocardiogram obtained the following day revealed a small residual pericardial effusion. The MVA was measured at 1.8 cm² on planimetry with a mean MV gradient of 5 mmHg. Only a mild degree of mitral regurgitation was seen. A significant reduction in tricuspid valve regurgitation was also observed (mild to moderate) , as well as the PA pressure, with an estimated PASP of 30 mmHg. No flow was seen across the IAS on color doppler.

Three weeks later, the patient presented with chest pressure and increasing dyspnea and was found to have a moderate to large circumferential pericardial effusion with tamponade. At 34-weeks of gestation, she underwent an urgent caesarean section with bilateral tubal ligation. The pericardial effusion was drained surgically and yielded serous fluid. Intraoperative inspection of the LA and PA revealed no tear or laceration. Three days later, a contrast cardiac computed tomogram was performed and showed a diverticulum in the supero-anterior aspect of the LA roof immediately adjacent to the IAS (Figure-2). There was minimal contrast extravasation. This was managed conservatively. At one month, a repeat echocardiogram revealed no re-accumulation.

Transseptal puncture is associated with adverse events in 1:100 cases. Commonly described complications include cardiac tamponade, inadvertent aortic puncture, systemic and cerebral embolism, and persistence of an iatrogenic septal defect. Aortic puncture is rare, but life-threatening and occurs in 0.05% of the cases. It usually happens in situations where excessive rotation of the heart distorts the usual relationship between the aortic root and fossa ovalis and the corresponding fluoroscopic landmarks.

This was likely the main mechanism of PA injury in our case. The 30-wk gravid uterus displaced the diaphragm upwards, and confounded by further cephalad migration of the diaphragm by the supine position required for the procedure, resulted in the myocardium being more horizontally placed. As a result, the already right-ward bulging IAS, was now, tilted to a more horizontal configuration, positioning the fossa ovalis farther away from the transseptal assembly dropping from the superior vena cava, consistently biasing it to a more superior location along the IAS, or causing it to slip superiorly if at all it were to engage in the mid-septum. The needle penetrating the IAS would immediately encounter the root of the LA and in our case, readily exited into the dilated right main PA coursing over the LA. Perhaps one favourable modification to the septal puncture technique would be to use a more angulated needle (e.g. BRK-1, or BRK-2), which would engage a lower position in the IAS. Potential difficulties in crossing the MV due to a low puncture could be overcome using the over-the-wire technique.

Recently, specialized devices have been introduced to refine the technique of transseptal access and allow for a more controlled puncture. Among these are the needle-on-wire devices such as the SafeSept® transseptal guidewire [Pressure Products] or the radiofrequency-based VersaCross® guidewire [Baylis Medical]. Once the needle tip punctures the septum and as it advances without dilator support, these guidewires assume an atraumatic curved shape rendering them incapable of further penetration. Unfortunately, neither of these specialized guidewires was available to us at the time.

We followed the same principle described in the literature on managing aortic punctures. ^{,  ,}  . A 0.032” guide wire was secured into the distal left PA and a slow, and gradual withdrawal of the dilator was performed into the LA cavity. It conceivable that the flap raised in the PA was aligned parallel to the direction of blood flow and in conjunction with near systemic PA pressure, sealed the localized perforation. Several bail-out options could be considered including surgical repair, and the use of a septal occluder to close the LA-PA track. In our case, the track fortunately sealed spontaneously, allowing us to complete the valvuloplasty. It is worth mentioning that the second presentation with cardiac tamponade was due to a reactive pericardial effusion developing in response to the original hemopericardium. This was confirmed intraoperatively when a non-hemorrhagic serous collection was drained.