Hypoplastic left heart syndrome is a severe cardiac malformation that will result in neonatal death if untreated. Despite a high procedural success of surgical treatment, there is a considerable early and late morbidity and mortality.
Here we present early postoperative interventional aortic valve closure for severe aortic regurgitation in a neonate after Norwood procedure as a novel procedure.
Case report
A neonate was born at 39 weeks of gestation with a prenatal diagnose of hypoplastic left heart syndrome confirmed postnatally. In echocardiography, although the valve diameters were reasonable in size (MiV 10 mm, AoV 5 mm), both the mitral and the aortic valves showed mild regurgitation and nearly no antegrade flow. Severe endocardial fibroelastosis and very poor function of the left ventricle were present. The child was referred to the German Heart Centre Munich for a Norwood procedure which was performed at 2 weeks of age with a modified Blalock–Taussig shunt 3.5 mm. The early post-operative course was uneventful; extubation was possible on post-operative day 2. However, the child developed increasing signs of heart failure with an elevated NT-proBNP > 35,000 ng/L and the need for high doses of intravenously administered diuretics. Echocardiography demonstrated an increase of aortic and mitral valve regurgitation (Fig 1). During the Norwood operation, both valves had not been touched by the surgeon. Three weeks after the Norwood operation, a cardiac catheterisation in deep sedation was scheduled with the intention to close the aortic valve for abolishment of aortic regurgitation. Both femoral vessels were cannulated (venous sheath 5F, arterial sheath 4F). Central venous pressures were around 11 mmHg, left ventricular pressures were 55/7/29, and ascending aorta pressures were 69/40/43 mmHg, respectively. Hence, the systolic aortic pressures were exceeding the systolic LV pressures. The arterial oxygen saturation was 85%. An angiogram into the ascending aorta showed severe aortic regurgitation. The aortic root had a diameter of 10 mm. The left ventricle was entered with a 0.014 coronary wire from the aorta, and a 4F catheter was placed into the LV. An AmplatzerTM Duct Occluder 2-03-04 was prepared and delivered through the 4F delivery catheter. This device was chosen because the disc diameters are 9 mm, and care had to be taken not to occlude the coronary arterial origins. The delivery and correct positioning of the device was controlled with transthoracic echocardiography. Angiography revealed unobstructed coronary arteries and only a minimal residual shunt across the aortic valve (Fig 2). Before hospital discharge, echocardiography documented correct position of the Amplatzer Occluder with only minimal shunt from the aorta to the left ventricle and mild to moderate mitral regurgitation. At the left ventricular site of the Occluder, a possible thrombus formation with a diameter 9 x 3 mm was noticed. Although the elevated NT-proBNP values remained unchanged, the child recovered completely, was put on oral diuretics and aspirin (5 mg/kg/d), and was discharged home 5 weeks after the Norwood operation, 2 weeks after device closure of the aortic valve. Unfortunately, 2 weeks after hospital discharge, the child experienced sudden cardiorespiratory arrest, was unsuccessfully resuscitated in a nearby hospital, and died.
Figure 1. Echocardiography demonstrated an increase of aortic and mitral valve regurgitation.
Figure 2. An angiogram into the ascending aorta and into the left ventricle showed a position of the Amplatzer Occluder. Both coronary arterial origins were left unobstructed.
Discussion
This report shows that off-label use of Amplatzer Duct Occluder 2 to close an aortic valve in a critically ill neonate after Norwood operation who suffered from aortic regurgitation and hemodynamic instability is feasible. Off-label use of such devices has already been described.Reference Fischer, Smevik, Novoa, Suares, Kramer and Bjornstad1–Reference Elling, Stiller and Grohmann4
Our patient experienced instant clinical improvement, intravenous diuretics could be changed to oral administration and the child was able to drink his food formula from the bottle. Two weeks after the catheter intervention, he was discharged home. Congenital aortic and mitral regurgitation in patients with HLHS is rather uncommon. Aortic regurgitation may occur after aortic balloon valvuloplasty (AoVP) in patients with borderline left ventricle.Reference Eicken, Georgiev, Balling, Schreiber, Hager and Hess5 Aortic regurgitation after AoVP is a known risk factor for a subsequent Norwood operation.Reference Rhodes, Colan, Perry, Jonas and Sanders6 In fact, in this old publication, severe aortic regurgitation was a contra indication for a Norwood operation.
Our patient was clinically not stable after a successful Norwood operation. He needed i.v. diuretics and was too weak for oral feeding. A surgical reintervention with aortic valve closure was considered high risk, and it was decided to close the aortic valve by catheter intervention. An Amplatzer Duct Occluder 2-03-04 was chosen because the disc diameters are 9 mm, aortic root diameter was 10 mm, and care had to be taken not to occlude the coronary arterial origins. After device placement, angiography revealed unobstructed coronary arteries and only a minimal residual shunt across the aortic valve. However, echocardiography before discharge revealed possible thrombus formation at the left ventricular site of the Occluder that was not visible again 1 week after hospital discharge in routine follow-up. The child was clinically well, with saturations about 80%, with adequate gain weight, and with echo finding of good contractility of systemic ventricle. Unfortunately, 2 weeks after hospital discharge, the child experienced sudden cardiorespiratory arrest, was unsuccessfully resuscitated in a nearby hospital, and died.
There is insufficient evidence and no consensus for optimal anticoagulant prophylaxis or treatment in children with CHD.Reference Whitlock, Sun, Fremes, Rubens and Teoh7 Hypoplastic left heart patients with aortic stenosis or patients with critical aortic stenosis undergoing the Norwood procedure can have large native aortic roots. This can result in areas with relatively flow within the aortic root and maybe predisposing the thrombus formation. Additional device in that area certainly brings additional risk for thrombus formation. Estimated risk for thromboembolic events caused by the mitral valve regurgitation seemed to be low. The cause of the acute death of the child remains unknown. No post-mortem examination was performed. Possible causes for death after a Norwood operation (interstage mortality) are shunt failure, infections, aortic arch obstruction, low cardiac output, arrhythmia, and coronary obstruction.Reference Simsic, Bradley, Stroud and Atz8, Reference Delmo Walter, Hübler and Alexi-Meskishvili9 Possibly, the device could have obstructed the coronary arterial origins, or a thrombus could have developed in that region. Maybe, aspirin might not be enough for anticoagulation. It remains speculative, however, would the additional anticoagulation drug change the course. Infants who undergo Norwood stage 1 palliation continue with high-risk circulation until stage 2 palliation. Routine care during the interstage period is associated with 10–20% mortality.Reference Rudd, Frommelt and Tweddell10 Although the child was included in home monitoring programme, risk of sudden death can never be completely abolished. Finally, the severely elevated NT-proBNP values which were present at hospital discharge point to a not ideal hemodynamical situation may have been the cause for the poor outcome.
Acknowledgement
We would like to thank Prof. Peter Ewert, Prof. Ivan Malcic, and Dr Tanase, who were included in decision making and treating this difficult patient.
Financial Support
This research received no specific grant from any funding agency, commercial, or not-for-profit sectors.
Conflict of Interest
None.
