Biventricular Conversion After Left Ventricular Recruitment Procedure for Hypoplastic Left Heart Variant and VSD

Purpose: The incidence of long-term Fontan complications have led some centers to reevaluate their “functionally single ventricle” patients for different surgical strategies. [1] Other centers have described their short-term outcomes with biventricular (BiV) conversions for patients with small left-sided heart structures. [2]

Methods: We present a video case report of the course and operations for a patient with hypoplastic left heart variant and a ventricular septal defect.

Results: A 4-year-old female who had undergone a Norwood and bidirectional Glenn operation at an outside institution was referred for consideration of biventricular conversion. Based on our evaluation, the mitral valve z-score was -2.5 and the left ventricular volume at end-diastole z-score of -6.1 with a non-apex-forming left ventricle, which are borderline for primary biventricular conversion so we proceeded toward left ventricular (LV) recruitment. 10 months later, she was brought back where a magnetic resonance imaging (MRI) showed that the left ventricle had grown with an LV end-diastolic volume index increase from 13.8 to 30.5 ml/m2. The mitral valve size did not change. Cardiac catheterization showed at a Qp:Qs of 0.8:1, a mitral gradient of 3 mm Hg and an LV end-diastolic pressure of 11 mm Hg.

She was a borderline but acceptable candidate for BiV conversion so we decided to do her BiV conversion in two stages. The goal of the first operation was to repair the mitral valve, enlarge the LV outflow tract, ventricular septal defect closure, ascending aortic replacement, and then we monitored her left atrial pressures to see if she would tolerate full septation. Left atrial pressures during this immediate postoperative course were 10-12 mmHg.

Because of this, we felt that she was a good candidate for full BiV conversion. This included DKS and Glenn takedown, supravalvar aortoplasty, pulmonary artery augmentation, and main pulmonary artery interposition graft. Postoperative echocardiogram showed good function, there was no flow acceleration across the aortic valve and a mean inflow gradient of 3 to 4 mmHg across the mitral valve. Repeat catheterization after complete BiV conversion showed with a Qp:Qs of 1:1, LV end-diastolic pressure of 5 mmHg, pulmonary capillary wedge pressure of 13 mmHg, and right ventricular pressures about 65% of LV.
At last follow-up, 3 months after her BiV conversion, MRI showed an indexed left ventricular end-diastolic volume of 59.7 mL/m2. As an outpatient, she is clinically asymptomatic with twice-daily furosemide and nadolol.

Conclusions: Short-term outcomes have been satisfactory. As others have found there is the potential for increased re-interventions including pacemakers and elevated left ventricular diastolic pressures. Continued follow-up will elucidate how this strategy compares to the long-term Fontan outcomes in the modern era.

References

1. D’Udekem Y, Iyengar AJ, Galati JC. Redefining expectations of long-term survival after the Fontan procedure: Twenty-five years of follow-up from the entire population of Australia and New Zealand. Circulation 2014;130:S32-S38.
2. Kalish BT, Banka P, Lafranchi T, Tworetzky W, delNido P, Emani SM. Biventricular conversion after single ventricle palliation in patients with small left heart structures: short-term outcomes. Ann Thorac Surg 2013;96:1406-12.

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