Discussion

This case highlights that an atrial septal defect with left ventricular diastolic dysfunction might require early intervention and that fenestrated atrial septal defect closure is a safe and effective treatment for such a condition.

Left ventricular diastolic dysfunction may necessitate early surgery for an atrial septal defect. The patient was diagnosed with hypertrophic cardiomyopathy, and left ventricular diastolic dysfunction was evidenced by an echocardiogram and confirmed through a closing test of the atrial septal defect in postoperative cardiac catheterisation. Right ventricular enlargement related to a large atrial septal defect worsened due to pulmonary hypertension from lung congestion accompanied by convulsions and a respiratory tract infection. Inhaled nitric oxide treatment caused right ventricular shrinkage, left ventricular enlargement, and a dramatic increase in urine output. We hypothesised that the enlarged right ventricle pressed the left ventricle and worsened left ventricular diastolic dysfunction. The central venous pressure was 15 mmHg; however, a bidirectional shunt predominantly favoured left-to-right shunting across the atrial septum. Therefore, the inflow to the left ventricle decreased, and low cardiac output symptoms emerged. Neurogenic pulmonary oedema accompanied by convulsions is a cause of lung congestion. Although we used anti-epileptic drugs, the patient experienced recurrent seizures. Cardiofaciocutaneous syndrome is a RASopathy similar to Noonan syndrome but more frequently complicated with infantile spasms and neurodevelopmental delay. ^{Reference Pierpont, Magoulas and Adi1}

Giardini et al. showed that by closing an atrial septal defect, the right ventricle’s volume overload decreased while the left ventricular diastolic dysfunction improved. ^{Reference Giardini, Moore, Brook, Stratton and Tacy2} This suggests that ventricular interdependence is involved in ventricle diastolic dysfunction. In our case, inhaled nitric oxide improved pulmonary hypertension. The shrunken right ventricle released the left ventricle from suppression, increasing urine output and the left ventricular outlet tract’s velocity time integral.

Complete closure of an atrial septal defect with left ventricular diastolic dysfunction may increase left atrial pressure, followed by lung congestion. To ensure that the atrial septal defect could be closed without complications, we needed to conduct a closing test. However, the patient’s body was relatively small to insert an occlusion device for a large atrial septal defect preoperatively. In an adult case of atrial septal defect with hypertrophic cardiomyopathy, a closing test using a percutaneous closure device was conducted. If pulmonary artery pressure and pulmonary artery wedge pressure increased post-closure, a percutaneous fenestrated atrial septal defect occlusion device was selected, or diuretics, nitroglycerin, and vasoactive drugs were used. ^{Reference Lim, Bergin and Ragosta3} Adaptation criteria for using a fenestrated occlusion device have not been definitively decided; however, if the left atrial pressure increased over 4 mmHg during a closing test ^{Reference Holzer, Cao and Hijazi4} or exceeded 16 mmHg after a closing test, ^{Reference Abdelkarim, Levi, Tran, Ghobrial and Aboulhosn5} a fenestrated device is recommended. We performed partial atrial septal defect closure using a fenestrated patch. The fenestration size was based on a report of left ventricular rehabilitation to a border zone left ventricular hypoplasia conducting atrial septal defect closure with a 4 mm fenestration. ^{Reference Emani, McElhinney and Tworetzky6} Balloon dilation of the fenestration stenosis using an expanded polytetrafluoroethylene graft is reportedly effective in a post-fenestrated Fontan operation ^{Reference Kreutzer, Lock, Jonas and Keane7 _;} we performed partial atrial septal defect closure using an expanded polytetrafluoroethylene patch anticipating that balloon dilation might be necessary.

In our case, postoperative cardiac catheterisation revealed reduced pulmonary flow and low left atrial pressure. The reported risk factors for lung congestion post-atrial septal defect closure include a left atrial pressure of>10 mmHg pre-closure ^{Reference Ewert, Berger and Nagdyman8} or left ventricular end-diastolic pressure of>10 mmHg post-closure. ^{Reference Schubert, Peters, Abdul‐Khaliq, Nagdyman, Lange and Ewert9} In our case, the left atrial and left ventricular end-diastolic pressures were elevated during the closing test, making complete atrial septal defect closure risky. Paediatric cardiac catheterisation is usually performed under sedation, and evaluation using atrial septal defect occlusion alone is inaccurate. Volume load and abdominal compression are also recommended. ^{Reference Satoshi and Hideaki10} If pulmonary hypertension worsens and is unrelated to high pulmonary flow, balloon dilation to the fenestration of an atrial septal defect would be needed, considering the left ventricular diastolic dysfunction involvement.