In hypoplastic left heart syndrome, the size and function of the left ventricle varies, usually dependent on the patency of the mitral and aortic valves. In patients with aortic and mitral atresia, the left ventricle can be indistinguishable and does not contribute to cardiac output. With a patent mitral valve and atretic aortic valve, impaired ventriculo-ventriculo interactions and risks of coronary sinusoids can negatively influence single right ventricular function. However, in patients with patent mitral and aortic valves, the LV can eject, augmenting cardiac output. There is some evidence to suggest that native aortic blood flow may improve short-term survival after single ventricle palliation in patients with hypoplastic left heart syndrome and aortic stenosis. Reference Ashburn, McCrindle and Tchervenkov1,Reference Tweddell, Sleeper and Ohye2
Surgical intervention to optimise anterograde aortic blood flow in patients with hypoplastic left heart syndrome with a patent mitral and aortic valve by aortic valvuloplasty at the time of Norwood is not routinely performed and has not been investigated by review of existing literature. This is likely related to the potential risk of creating significant aortic regurgitation. Native aortic regurgitation can contribute to coronary steal, Reference Fürniss, Kubicki, Stiller, Reineker, Siepe and Grohmann3 and coronary ischaemia contributes significantly to morbidity and mortality. Reference Elling, Stiller and Grohmann4
We evaluated the impact of native aortic valvuloplasty at the time of the Norwood operation on long-term outcomes, degree of native aortic valve regurgitation, and systolic left ventricular size and function in patients with hypoplastic left heart syndrome. We hypothesise that these patients benefit from increased cardiac output from left ventricular ejection without the development of important native aortic regurgitation.
Methods
We performed a retrospective cohort study of patients with hypoplastic left heart syndrome with a stenotic aortic valve who underwent native aortic valvuloplasty at the time of Norwood palliation at Children’s Wisconsin from 2002 to 2021. This was a retrospective study for which no data was generated, and a waiver of consent was approved (IRB 1703133-1. Approved February 2021). We assessed survival, NYHA classification, cardiac symptoms/complications, current medications, patency of the native aortic valve and qualitative degree of aortic and tricuspid regurgitation by colour Doppler, right ventricular function by echo-derived peak longitudinal strain, and left ventricular volume and ejection fraction on the most recent echocardiogram.
Results
Eight patients were identified who underwent native aortic valvuloplasty at the time of Norwood operation. Despite anterograde aortic blood flow, all these patients underwent single ventricle palliation based on aortic and mitral valve and left ventricular hypoplasia. The median aortic valve annulus z-score was –3.25 and the median mitral valve annulus z-score was –2.4. All patients had abnormal aortic valve anatomy with severe stenosis and no regurgitation at their initial neonatal echocardiogram. Four patients had unicuspid valves and the other four had bicuspid valves. The decision to proceed with aortic valvuloplasty at the time of Norwood was based on pre-operative discussion as well as intra-operative decision making. The median age at the time of Norwood was 7 days (range 6–13 days) with a mean weight of 3.06 kg (range 2.5–3.4 kg). Of these patients, three underwent a Blalock-Taussig-Thomas shunt while five underwent placement of a right ventricle-pulmonary artery conduit. One patient died during the interstage period secondary to prematurity and perioperative bacterial sepsis. They were born at 32 weeks gestation with a birth weight < 2 kg. After initial Stage I palliation with a 5.0 Sano conduit and aortic valvotomy, they developed staphylococcus aureus sepsis and subsequent refractory septic shock prompting withdrawal of care. The other seven survived through Fontan palliation. On most recent echocardiographic evaluation, all seven patients maintained native aortic valve patency with the identifiable anterograde flow; native aortic regurgitation was considered insignificant in six of the five patients (three had trivial, three had mild, and one had moderate regurgitation). Two patients were lost to follow-up after their Fontan. The other five are alive with Fontan circulation at a median follow-up of 12 years (range 3–17 years). The median indexed left ventricular volume at their most recent echocardiogram demonstrated small cavities in all patients (mean 23.8 ml/body surface area (BSA), range 7.2–32.3 ml/BSA) with functioning ventricle based on a median left ventricular ejection fraction of 57.8% (range 29.8–65.7%). All five patients had good systolic right ventricular function (mean peak longitudinal strain −16.1%, range −11.7 to −18.9%). All had good clinical functional status, with four patients having no significant symptomatology, consistent with class I heart failure by NYHA Classification, and one patient having class II heart failure. No patients had lab or imaging evidence of significant tricuspid regurgitation, protein-losing enteropathy, plastic bronchitis, or liver failure.
Discussion
In our small series, native aortic valvuloplasty at the time of Norwood preserved aortic valve patency without the development of clinically significant aortic regurgitation or left ventricular chamber dilation at intermediate follow-up. In addition, patency of the native aortic valve was associated with preserved left ventricular ejection that should augment cardiac output. Although the overall benefit is difficult to attribute solely to the valvuloplasty in our cohort, there were no identified detrimental effects with excellent intermediate transplant-free survival, well-maintained right ventricular function, and good functional clinical status. Although this case series is encouraging, it includes few patients; additionally, long-term surveillance is needed, as late progressive native aortic regurgitation could impact coronary reserve and result in detrimental effects on both left and right ventricular function.
Conclusions
Native aortic valvuloplasty can be safely performed at the time of Norwood operation in patients with hypoplastic left heart syndrome and associated aortic stenosis without intermediate risk of clinically significant aortic regurgitation. It is well tolerated without adverse effects on right ventricular function or clinical symptomatology. In addition, the procedure appears to promote continued left ventricular ejection/anterograde flow without the development of significant left ventricular chamber dilation, beneficially contributing to total cardiac output.
Acknowledgements
Thanks to the Herma Heart Institute at the Medical College of Wisconsin and Children’s Support.
Financial support
This research received no specific grant from any funding agency, commercial, or not-for-profit sectors.
Conflicts of interest
None.
Ethical standards
This was a retrospective study for which no data was generated, and a waiver of consent was approved by our IRB.
