Ross-Konno and Endocardial Fibroelastosis Resection After Hybrid Stage I Palliation in Infancy: Successful Staged Left-Ventricular Rehabilitation and Conversion to Biventricular Circulation After Fetal Diagnosis of Aortic Stenosis
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We report a patient who presented during fetal life with severe aortic stenosis, left-ventricular dysfunction, and endocardial fibroelastosis (evolving hypoplastic left heart syndrome). Management involved in utero and postnatal balloon aortic valvuloplasty for partial relief of obstruction and early postnatal hybrid stage I palliation until recovery of left-ventricular systolic function had occurred. The infant subsequently had successful conversion to a biventricular circulation by combining resection of endocardial fibroelastosis with single-stage Ross-Konno, aortic arch reconstruction, hybrid takedown, and pulmonary artery reconstruction.
KeywordsAortic stenosis Fetal balloon aortic valvuloplasty Fetal intervention Hypoplastic left heart syndrome Resection of endocardial fibroelastosis Stage 1 hybrid
The morphologic and functional spectrum of the left ventricle in severe aortic stenosis ranges from the smaller, hypertrophied “borderline” left ventricle to the dilated and thin-walled left ventricle. In addition, several studies have demonstrated that aortic stenosis with left-ventricular dysfunction presenting in fetal life may lead to hypoplastic left heart syndrome at birth, with varying degrees of chamber hypoplasia and endocardial fibroelastosis (EFE) [6, 8, 10]. Neonates with severe aortic stenosis generally require either surgical valvotomy or transcatheter balloon valvuloplasty , whereas those with hypoplastic left heart are generally managed with univentricular palliation (Norwood or hybrid transcatheter-surgical techniques) or cardiac transplantation.
On day of life 14, with no change in clinical status or LVEF%, the child underwent stage I hybrid palliation with placement of an 18-mm ductal stent and bilateral pulmonary artery banding. Repeat dilation of the aortic valve was performed at that time, resulting in a decrease in peak-to-peak gradient to 11 mm Hg and mild to moderate aortic insufficiency.
Experimental models involving surgically created aortic obstruction do not recapitulate the human phenotype ; therefore, study of the pathophysiology of this disease has been difficult. However, natural history studies have shown that in the presence of certain physiologic findings (specifically left-to-right atrial shunting and retrograde aortic arch perfusion in fetal life), progression to hypoplastic left heart syndrome at term can be reliably predicted . The rationale for fetal aortic valvuloplasty is to relieve aortic obstruction and promote antegrade flow through the left heart and aorta. With restoration of antegrade flow, we observed continued growth of the left heart structures through the remainder of gestation; however, ventricular function did not improve appreciably. The reason for this is speculative, but it has been proposed that the fetal left ventricle responds to obstruction with increase in mass without increase in capillary density, which may result in a hypertrophied myocardium with increased susceptibility to ischemia [9, 12]. The extensive EFE in this patient as well as the observed hypertrophy might support this theory. Fetal valvuloplasty partially relieved the obstruction, and after birth we undertook a combined approach that may have further mitigated the effect of long-standing obstruction and ischemic insult through relief of obstruction (by way of additional valvuloplasties) and decrease in preload (left atrial decompression with atrial stenting). Facilitating antegrade perfusion of the aorta and coronary circulation with normally saturated blood, along with improvement in myocardial perfusion, may have contributed to the slow improvement in the patient’s systolic and diastolic function.
Previous reports have also documented the possibility of reversible severe left-ventricular dysfunction and ventricular growth in the neonate [1, 2, 5]. Emani et al.  reported a series of patients with borderline left heart disease who underwent “primary left-ventricular rehabilitation” at a median age of 5.6 months, with aortic and/or mitral valve surgery and EFE resection, with good short-term results and no deaths at a median follow-up of 25 months. Our case, however, represents the first report to our knowledge of a patient initially palliated with a hybrid transcatheter-surgical approach after fetal intervention followed by successful surgical takedown of the hybrid and conversion to biventricular circulation by adding Ross-Konno procedure and aortic arch reconstruction to the EFE resection.
Long-term outcome for patients undergoing extensive EFE resection as part of left-ventricular rehabilitation are unknown. Medium-term results from patients undergoing neonatal Ross-Konno procedures have been mixed, and particularly poor results in patients requiring concomitant aortic arch reconstruction have been noted. However, a recent large single-center experience  suggested that overall survival and functional status may represent improvement compared with single-ventricle palliation or neonatal transplantation. Certainly long-term follow-up data, including evaluation of functional and neurodevelopmental status and comorbidities (including pulmonary vascular disease) will be needed before there is widespread adoption of this type of approach. However, feasibility of induction of significant left heart structure growth and significant myocardial recovery allowing restoration of biventricular circulation is certainly suggested by our case and deserves further study.
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