This study was conducted in compliance with the Declaration of Helsinki. The patient provided written informed consent for using their clinical data for scientific presentations or publications.
A 37-year-old female suffered from extremely severe PH was referred to our institute for redo MVR. At the age of 2 years, a partial AVSD was diagnosed but she could glow up without critical symptoms (New York Heart Association [NYHA] Class II). At the age of 25 years, she had surgical treatment for a partial AVSD, moderate to severe mitral valve regurgitation, and moderate to severe tricuspid valve regurgitation; patch closure for a partial AVSD, mitral valve replacement using a 31 mm Carpentier Edwards Perimount bioprosthesis (Edwards Lifesciences, Irvine, CA, USA) at the juxta-annular position, and tricuspid suture annuloplasty using a Kay’s technique at the other hospital. After that, pacemaker implantation was also carried out for complete atrioventricular block. Three years prior to the presentation, she developed dyspnea on exertion (NYHA Class III) and was referred to our institute for extremely severe PH.
Preoperative laboratory data indicated heart failure, with an N-terminal pro-brain natriuretic peptide levels of 993 pg/ml. Chest radiograph showed cardiomegaly involving the right cavities and notable enlargement of the pulmonary arch (Fig. 1A). Computed tomography also showed notable enlargement of the pulmonary arch (Fig. 1B) combined with severe calcification of the bioprosthesis (Fig. 1C) and severe adhesion of previous pacing wires on the right atrium (Fig. 1D). Transthoracic echocardiography showed a small left ventricle compressed by a dilated right ventricle (Fig. 2A) and extremely severe PH with an estimated right ventricular pressure of 112 mmHg. Echocardiography revealed LVOTO due to stent post protrusion of the mitral bioprosthesis (Fig. 2B) and its severe calcified change. Right heart catheter examination revealed features that indicated severe PH with the following parametric values: pulmonary artery pressure (PAP) of 104/43 mmHg (mean, 64 mmHg), which was equally to the systemic arterial blood pressure; calculated total pulmonary resistance (TPR) of 1,462 dynes/sec/cm− 5, and pulmonary vascular resistance (PVR) of 891 dynes/sec/cm− 5. Initially, pulmonary arterial hypertension (group-I PH) was considered due to the patient's long-term history of congenital heart disease, but coexisting group-II PH was also considered. Preoperatively, since pulmonary congestion was concerned, low-dose prostaglandin I2 was administered for treatment of her PH. Because the extreme PH above 100 mmHg was considered to be caused by both LVOTO due to stent post protrusion and severe calcification of the mitral bioprosthesis, surgical repair of redo mitral valve replacement was planned.
Redo mitral valve replacement through a median re-sternotomy was performed. There was a marked dilatation of the pulmonary artery and a severe adhesion of previous pacing wires on the right atrium. After careful dissection of the adhesion, cardiopulmonary bypass was instituted via bicaval drainage and ascending aortic cannulation. Because retrograde cardioplegia was impossible because of existence of patent left superior vena cava, cardiac arrest was achieved using antegrade cardioplegia, and exposure of the mitral valve prosthesis was performed through the left atrium. Eventually, it was revealed that the patent left superior vena cava was connected to the left atrium. Severe stenosis in the LVOT due to stent post protrusion (Fig. 3A) and severe calcification of the mitral bioprosthesis (Fig. 3B) were observed. Because LVOT was narrowed and the native aortic valve was so close to the juxtapositioned mitral bioprosthesis in the AVSD heart, removal of the previous prosthetic mitral valve was quite difficult. The protruding strut were highly adherent to the LVOT and the accidental injury of the noncoronary aortic cusp was detected through the antegrade cardioplegia. Redo mitral valve replacement at the supra-annular position was performed using a 25-mm SJM Regent mechanical valve (St. Jude Medical, St. Paul, MN, USA) along with annular plication using a bovine pericardium collar (Fig. 3C). The aortic valve repair seemed to be difficult because the cusp was extremely vulnerable and fragile, which was eventually replaced. Initially we chose 17-mm SJM Regent mechanical valve, however, it was impossible to sit in the small annulus, then, we replaced using a 16-mm ATS-AP mechanical valve (Medtronic, Minneapolis, MN, USA) in the tilted position. The ascending aorta wall was also vulnerable, so two layers mattress sutures with 5 − 0 Prolene were used for closure. Tricuspid valve annuloplasty for severe tricuspid regurgitation using a 27-mm SJM Tailor band (St. Jude Medical) and closure of the atrial septal defect with bovine pericardial patch after removal of previous calcified patch were performed. Weaning from cardiopulmonary bypass was achieved with administration of inotropics and low-dose prostaglandin I2, but pulmonary artery pressure remained high at 60% of the systemic pressure. Extubation was achieved on the second day of surgery with high dose inotropics and oxygen supply, then we added oral medication with Bosentan hydrate in addition to anticoagulant therapy. Postoperative echocardiography showed improvement of LVOTO (Fig. 2C). Postoperative right heart catheter examination revealed that the mean PAP of 43 mmHg, calculated TPR of 937 dynes/sec/cm− 5, and PVR of 643 dynes/sec/cm− 5. Subsequently, the patient was discharged on postoperative day 43 after sufficient rehabilitation and meticulous medication, but requirement of home oxygen therapy for hypoxia was maintained. Because the mechanical valve in the aortic valve position was small for her body size, the maximum velocity through the aortic mechanical valve was 3.1 m/s, peak and mean pressure gradient were 38 and 20 mmHg even with no obvious symptoms related to heart failure. Two years postoperatively, her oxygen level was improved to the almost normal range, and her PAP decreased to almost normal ranges, with a systolic PAP of 26 mmHg. She is still doing well (NYHA class II), without any major adverse cardiovascular events after 6 years of follow-up. The latest maximum velocity through the aortic mechanical valve was 3.2 m/s and the peak and mean pressure gradient were 42 and 21 mmHg.