Non-cardiac surgery in congenital heart disease-associated pulmonary arterial hypertension: risk recognition and management

Current guidelines for the peri-operative assessment and management are not sufficient to allow effective risk assessment and management of the patient with pulmonary arterial hypertension associated with congenital heart disease. Well-established risk stratification tools are not validated in this group. Additional, disease-specific risks require individualised, specialist, multidisciplinary management. We present an illustrative clinical case of patients with pulmonary arterial hypertension associated with congenital heart disease undergoing non-cardiac surgery. The case follows a 66-year-old male with pulmonary hypertension associated with an atrial septal defect underwent an elective hernia repair. We discuss useful management strategies for minimising risk during the peri- and post-operative periods in this population.

symptoms, making NYHA functional class a poor surrogate of exercise capacity in this population [9]. Individuals with PAH-CHD have additional disease-specific risks, which require meticulous, directed management depending on the mechanism of pulmonary hypertension, the degree of cyanosis and the presence of systemic ventricular dysfunction or severe obstructive valvular lesions. Hence, while it is accepted that general anaesthesia and sedation carry significant risks in all PAH-CHD patients, it is difficult to stratify patients within this group into higher-and lower-risk subjects (increased versus prohibitive risk). Therefore, accurate pre-operative risk evaluation in PAH-CHD should take into account the risk inherent to the specific procedure, traditional cardiac risk factors and the CHD-specific risks [6].
We present a clinical case which illustrates some of the specific risks encountered in PAH-CHD patients undergoing non-cardiac surgery.

Case presentation
A 66-year-old man attended the outpatient adult congenital heart disease (ACHD) clinic. He had a history of a large secundum atrial septal defect (ASD) and had presented 15 years earlier with paroxysmal atrial fibrillation. On presentation, the echocardiogram had shown evidence of pulmonary hypertension (PH), with an estimated right ventricular systolic pressure (RVSP) of 70 mmHg. After a detailed work-up, he was felt to be operable, but the patient declined ASD repair at this point.
He then developed a large irreducible inguinal hernia, which was impacting on his quality of life. He was reviewed by the general surgeons at his local district general hospital. The surgical team planned for operative management, and he was reviewed by an anaesthetist at pre-assessment. In clinic, he was in functional class II, on an ACE inhibitor for mild systemic hypertension and was a current smoker. He was not taking any anticoagulation or anti-platelet therapy. Examination revealed an oxygen saturation level of 93% on room air, a right ventricular heave with a fixed, split second heart sound and no pedal oedema. His 12-lead ECG showed atrial fibrillation ( Fig. 1). Following discussion with the surgical consultant, the patient's PAH-CHD team were contacted for advice on surgical risk and optimisation.
A full pre-operative assessment was undertaken at his PAH-CHD centre. Repeat echocardiography ( Fig. 2a &  b) showed that the RVSP was unchanged. He had moderate mitral regurgitation and moderate-severe tricuspid regurgitation with significant RV systolic impairment (tricuspid annular plane systolic excursion 8 mm, RV S′ 7 cm/s). On cardiopulmonary exercise testing he managed 5 min 38 s on a cycle ergometer, achieving a These results signified markedly impaired exercise capacity and the catheter data were suggestive of combined pre-and post-capillary pulmonary hypertension, with a significant precapillary component, 'out of proportion' with the severity of left heart disease (diastolic dysfunction of the left ventricle and moderate mitral regurgitation). A joint multi-disciplinary team meeting was held, which was attended by the PH and CHD teams, a senior cardiac anaesthetist and a general surgeon and imaging specialists. Various options for anaesthetic management were considered, including performing the hernia repair under local, epidural, spinal or general anaesthesia. Non-surgical options were also discussed given the high-risks status of the patient. The risk of a pulmonary hypertensive crisis and RV dysfunction were stressed, as well as the potential for haemodynamic instability and the need for effective pain management. The congenital cardiac anaesthetist considered the possibility of worsening of the PVR and right-to-left shunting whilst under general anaesthesia and intermittent positive pressure ventilation. The length of the operation and the degree of fluid shift were estimated and considered with the aid of the surgical team. Limiting the size of the incision to limit post-operative pain and the use of epidural anaesthesia versus patient-controlled analgesia were deliberated. The consensus was that the operation should be undertaken at the specialist centre. Due to the evidence of significant RV impairment in the context of severe pulmonary hypertension and the high perceived risk of a pulmonary hypertensive crisis, the experienced congenital cardiac anaesthetist opted for giving a general anaesthetic with close monitoring of RV function.
The patient decided to proceed with surgery and underwent general anaesthesia with extra precautions employed in a high-risk pulmonary hypertension case: The patient was allowed to drink free fluids until 1 h before anaesthesia, peripheral venous cannulation was performed with the patient awake and, once anaesthetised, central venous and peripheral arterial catheters were placed. Trans-oesophageal echocardiography was performed and inhaled nitric oxide was used early during surgery. Post-operatively, the patient was taken to the Intensive Care Unit asleep and was woken up gradually. He was discharged from hospital 3 days later.

Discussion and conclusions
PAH-CHD patients undergoing essential cardiac and non-cardiac surgery should be managed in a regional congenital heart disease (CHD) and PH centre with integrated care led by a cardiologist specialising in paediatric or adult CHD and PH. A thorough, multidisciplinary pre-assessment and meticulous perioperative management by an experienced cardiac anaesthetist should be presumed to be the standard of care, particularly in the absence of large prospective trials in this area [10][11][12]. The ES heart is highly preload dependent; fluid shifts can lead to a significant fall in cardiac output. Decreases in systemic vascular resistance (SVR) can enhance rightto-left shunt, worsening cyanosis and precipitating cardiovascular collapse. Increases in SVR can lead to a decrease in ventricular function, especially if associated with a sudden rise in PVR (PH crisis) [13]. This precarious physiology requires meticulous peri-operative management, with maintenance of SVR and ventricular contractility and avoidance of excessive blood loss and intravascular volume depletion. In cases of primary inguinal hernia repair, intraoperative fluid shifts are limited with experienced anaesthetic guidance, and preoperative dehydration was avoided by allowing the patient to drink clear fluids until 1 h prior to anaesthesia.
The intraoperative management is specific to the procedure being performed, but certain general principles should be followed. The preferred form of induction of anaesthesia is intravenous with systemic vasopressor agents available to maintain SVR [14]. In the past, there has been a perceived risk of inhalational anaesthetic agents having a less predictable effect on SVR, but many experienced anaesthetists use them successfully in combination with intravenous agents, reinforcing the importance of appropriate training and expertise of the anaesthetic team looking after these highly complex patients [11,15,16]. As with all cyanotic cardiac patients, the right-to-left shunt carries a risk of systemic paradoxical embolization, and all intravenous injections or infusions should be given through filtered or monitored lines.
Arterial monitoring is useful, as is intraoperative transoesophageal echocardiography (TOE) monitoring. Pulmonary artery catheters are generally avoided, however, due to the potential for complications [17], such as crossing the shunt lesion or pulmonary artery rupture [18]. If blood loss is anticipated, early cross-match is advised, as antibodies are common. When 'correcting' a low haemoglobin, normal reference values of less than 150 g/L should not be used, as patients with ES require a higher haemoglobin concentration than healthy adults, to compensate for the chronic hypoxaemia (secondary erythrocytosis) [19].
Finally, the patient, family and the treating teams should be prepared for an Intensive Care Unit stay and prolonged post-operative ventilation. The mortality rate of non-cardiac surgery in ES is reported around 3% in expert hands, even though the risks are likely to vary greatly according to the nature, complexity and urgency of the procedure (e.g. emergency cardiac surgery versus routine abdominal surgery versus dental procedures) [14].
Even when emergency surgery is required in a local hospital, telephone advice may be lifesaving for the patient as there are several disease-specific risks and precautions, which need to be considered and appropriately managed to increase the likelihood of a good outcome.