Severe subaortic stenosis that progressed over a 12-year period after cardiac surgery

Journal of Medical Ultrasonics (Impact Factor: 0.64). 01/2009; 36(4):211-214. DOI: 10.1007/s10396-009-0232-4

ABSTRACT A 12-year-old girl who had undergone cardiac surgery for ventricular septal defect (VSD), atrial septal defect (ASD), and
patent ductus arteriosus (PDA) in infancy was referred to our institution for fatigue and excessive sweating. Transthoracic
and transesophageal echocardiographic studies revealed tunnel-type subaortic stenosis with aortic valvular stenosis, for which
she underwent aortic valve replacement and myomectomy of left ventricular outflow tract. Progression of subaortic stenosis
should be considered in patients with only mild aortic valve stenosis after previous cardiovascular surgery. Echocardiography
contributed significantly to making the diagnosis and therapeutic decision in our patient.

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    ABSTRACT: The objective of this study was to show elevations in septal shear stress in response to morphologic abnormalities that have been associated with discrete subaortic stenosis (SAS) in children. Combined with the published data, this critical connection supports a four-stage etiology of SAS that is advanced in this report. Subaortic stenosis constitutes up to 20% of left ventricular outflow obstruction in children and frequently requires surgical removal, and the lesions may reappear unpredictably after the operation. The etiology of SAS is unknown. This study proposes a four-stage etiology for SAS that I) combines morphologic abnormalities, II) elevation of septal shear stress, III) genetic predisposition and IV) cellular proliferation in response to shear stress. Morphologic structures of a left ventricular outflow tract were modeled based on measurements in patients with and without SAS. Septal shear stress was studied in response to changes in aortoseptal angle (AoSA) (120 degrees to 150 degrees), outflow tract convergence angle (45 degrees, 22.5 degrees and 0 degree), presence/location of a ventricular septal defect (VSD) (3-mm VSD; 2 and 6 mm from annulus) and shunt velocity (3 and 5 m/s). Variations in AoSA produced marked elevations in septal shear stress (from 103 dynes/cm2 for 150 degrees angle to 150 dynes/cm2 for 120 degrees angle for baseline conditions). This effect was not dependent on the convergence angle in the outflow tract (150 to 132 dynes/cm2 over full range of angles including extreme case of 0 degree). A VSD enhanced this effect (150 to 220 dynes/cm2 at steep angle of 120 degrees and 3 m/s shunt velocity), consistent with the high incidence of VSDs in patients with SAS. The position of the VSD was also important, with a reduction of the distance between the VSD and the aortic annulus causing further increases in septal shear stress (220 and 266 dynes/cm2 for distances of 6 and 2 mm from the annulus, respectively). Small changes in AoSA produce important changes in septal shear stress. The levels of stress increase are consistent with cellular flow studies showing stimulation of growth factors and cellular proliferation. Steepened AoSA may be a risk factor for the development of SAS. Evidence exists for all four stages of the proposed etiology of SAS.
    Journal of the American College of Cardiology 08/1997; 30(1):247-54. · 14.09 Impact Factor
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    ABSTRACT: Secondary subaortic stenosis (SSS) can occur after surgery for various congenital heart defects with or without initial left ventricular outflow tract obstruction (LVOTO). The objective of this study was to highlight the anatomical lesions and surgical procedures associated with the development of SSS after surgery on defects without initial LVOTO. A retrospective study of 4710 patients was performed (1984-2005). The criterion for inclusion was a fixed subaortic obstruction requiring surgery, after an open- or closed-heart operation. The criterion for exclusion was an LVOTO at the time of the first operation. Twenty-eight patients were studied. The mean age at initial surgery was 32 months (4 days-47 years; median: 2 months). SSS occurred after three main types of surgery: repair of coarctation of the aorta, repair of AVSD and LV-aorta rerouting for double outlet right ventricle or transposition of great arteries. The mean delay of occurrence was 4.4 years (2 months-19 years). Frequently associated initial anatomical conditions were coarctation of the aorta (40%), lesions of the mitral valve (32%), bicuspid aortic valve (21%) and left superior vena cava (LSVC) (14%). Preoperative anatomical lesions of the LVOT were present in 93% of the cases. After the initial operation, only one patient had a mean echo-Doppler pressure gradient across the LVOT>20 mmHg. SSS was most frequently a subaortic membrane (n=23). The mean pressure gradient across SSS at the time of reoperation was 47+/-29 mmHg. Five patients developed a second SSS after 7.4 years (mean). One patient developed a third SSS. No patient died. When compared with patients without SSS, significant risk factors for SSS were low age at surgery (32 vs 74.9 months, p<10(-4)), pre-existing coarctation of the aorta (40 vs 10%, p<10(-4)), bicuspid aortic valve (21 vs 6%, p=0.002) and LSVC (14 vs 4%, p=0.02). SSS development is multifactorial, depending on initial anatomical lesions and initial surgery. Low age at initial surgery, coarctation of the aorta, bicuspid aortic valve and LSVC significantly increase the risk of SSS. These elements warrant long-term follow-up for early detection of SSS.
    European Journal of Cardio-Thoracic Surgery 11/2007; 32(4):582-7. · 2.67 Impact Factor
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    ABSTRACT: Data derived from serial hemodynamic and angiocardiographic investigations on pediatric patients not subjected to intervening intracardiac operations support the view that subaortic stenosis in congenital heart disease tends to be a progressive disorder. Our data are obtained from two groups of patients. The first comprised 22 patients with discrete subaortic stenosis in relative isolation. The second was made up of 19 patients with the fibrous or fibromuscular forms of discrete subaortic stenosis associated with a perimembranous ventricular septal defect. The results from both groups support our initial contention. The progressive character of subaortic stenosis in these two situations illustrates the dynamic nature of congenital heart disease, and the tendency of a changing form and function.
    International Journal of Cardiology 07/1985; 8(2):137-48. · 6.18 Impact Factor