Acquired discrete subaortic stenosis late after mitral valve replacement

Rheology of right ventricular outflow tract obstruction: sub-pulmonary membrane developing months after primary intervention to treat pulmonary atresia with intact interventricular septum

Isolated sub-pulmonary membrane is a rare condition, the origin of which has been debatable. Transcatheter treatment of pulmonary valve atresia with intact interventricular septum by radiofrequency perforation and balloon dilatation to restore biventricular circulation is gaining more popularity, with improving results over time. We report in our experience of 79 cases in 10 years the development of a sub-pulmonary membrane in 4 cases: causing significant obstruction requiring surgical excision in one case that revealed a fibrous membrane on pathology; causing mild right ventricular outflow tract obstruction in another and not yet causing obstruction in 2. On cardiac MRI, the right ventricular outflow tract and the right ventricular outflow tract/pulmonary atresia angle showed no morphological abnormalities.

Subaortic stenosis secondary to pannus from a mechanical mitral valve

A variety of conditions can lead to left ventricle outflow tract obstruction, but cases of subaortic stenosis decades following a mitral valve replacement are exceedingly rare. Any abnormal positioning of a prosthetic valve can result in continuous turbulence leading to permanent deposition of fibrous tissue. We present a case of a 56-year-old female that underwent mechanical mitral valve replacement, due to severe rheumatic mitral valve disease, with recurrent admissions for dyspnea. Ultimately, she underwent a left heart catheterization and during pullback from the left ventricle to the aorta a 100-mmHg pressure gradient was noted below the level of the aortic valve suggestive of subaortic stenosis. The subaortic stenosis was found to be secondary to pannus formation from her mitral valve prosthesis placed over twenty years ago. <Learning objective: Subaortic stenosis secondary to pannus formation decades following a mechanical mitral valve replacement is exceptionally rare. The diagnosis of subaortic stenosis can be extremely difficult requiring high clinical suspicion, transthoracic and transesophageal echocardiography, computed tomography, and/or pullback pressure during left heart catheterization.>.

Congenital, acquired, or both? The only two congenitally based, acquired heart diseases

Discrete subaortic stenosis (DSS) is a type of left ventricular outflow tract obstruction whereas double-chambered right ventricle is a form of right ventricular outflow tract obstruction. Both of these cardiac malformations share lots of similar characteristics which classify them as acquired developmental heart diseases despite their congenital anatomical substrate. Both of them are frequently associated to ventricular septal defects. The initial stimulus in their pathogenetic process is anatomical abnormalities or variations. Subsequently, a hemodynamic process is triggered finally leading to an abnormal subaortic fibroproliferative process with regard to DSS or to hypertrophy of ectopic muscles as far as double-chambered right ventricle is concerned. In many cases, these pathologies are developed secondarily to surgical management of other congenital or acquired heart defects. Moreover, high recurrence rates after initial successful surgical therapy, particularly regarding DSS, have been described. Finally, an interesting coexistence of DSS and double-chambered aortic ventricle has also been reported in some cases.

A novel case of late left ventricular outflow tract obstruction post mitral valve surgery

Left ventricular outflow tract (LVOT) obstruction (LVOTO) is a rare but recognized complication of mitral valve surgery. Concomitant factors can cause significant clinical deterioration which requires urgent intervention. We present the case of a female patient who underwent closed valvotomy at age 20 for mitral stenosis secondary to rheumatic heart disease. Seventeen years later, a re-stenosed valve prompted mitral valve replacement (MVR) with a Carbomedics mechanical prosthesis. 8 years later, she re-presented with increasing dyspnoea. On echocardiogram a frond-like structure was visible in the LVOT, the valve housing was protruding into the LVOT and she had marked septal hypertrophy. The LVOT gradient was 72 mmHg. This is a novel case of mechanical MVR associated LVOTO due to at least three discrete factors. This case demonstrates how multiple factors can amalgamate to result in significant clinical deterioration. Over an 8-year period, all three distinct factors contributed to the development of severe LVOTO.