Anaesthesia for percutaneous closure of atrial septal defects Patrick A Calvert BCh MA MRCP Andrew A Klein MBBS FRCA

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1 Anaesthesia for percutaneous closure of atrial septal defects Patrick A Calvert BCh MA MRCP Andrew A Klein MBBS FRCA Key points Percutaneous closure is the procedure of choice for the majority of patients with atrial septal defects and symptomatic patent foramen ovale (PFO). Closure of an ostium secundum atrial septal defect will prevent pulmonary hypertension due to left to right shunt and improves life expectancy. Cerebrovascular accident or transient cerebral event is an indication for closure of a PFO, as paradoxical embolus may be the cause. General anaesthesia is usually required, along with trans-oesophageal echocardiography; day case management is safe and cost-effective. Permanent complications are very rare, and patient satisfaction is high. Patrick A Calvert BCh MA MRCP SpR in Cardiology Papworth Hospital Papworth Everard Cambridge CB23 8RE UK Andrew A Klein MBBS FRCA Consultant in Anaesthesia and Critical care Papworth Hospital Papworth Everard Cambridge CB23 8RE UK andrew.klein@papworth.nhs.uk (for correspondence) Interventional cardiology has undergone considerable advances in device technology over the past 20 yr. Anaesthesia or sedation is required for a number of these procedures as pain or general discomfort is frequently a feature coupled with the requirement to lie supine and still for up to 1 h or more. Percutaneous atrial septal occlusion is a well developed and commonly performed intervention. Trans-oesophageal echocardiography (TOE) is required as a part of the procedure, which is most often carried out in the catheter lab under general anaesthesia. Percutaneous closure avoids the need for surgery and sternotomy, and is thus associated with significantly fewer complications and greater patient satisfaction. Indications The established indications for atrial septal occlusion are closure of an ostium secundum atrial septal defect (ASD) to prevent shunting of blood from the left to right atrium, and cryptogenic stroke or decompression illness secondary to a patent foramen ovale (PFO). Although ASD and PFO have been linked to migraine, there is currently no evidence to advocate defect closure for this indication. Septal closure for shunt: ASD ASDs account for approximately 10% of congenital cardiac defects and 22 40% of congenital heart disease in adults. 1 The major types of ASD are the following. (i) Ostium secundum ASD (60 70%) (Fig. 1). This is either caused by excessive resorbtion of the thin primum septum or deficient growth of the thicker secundum septum. It manifests after birth as a defect in the fossa ovalis lined by the thin primum septum. (ii) Ostium primum ASD (15 20%); a defect of the endocardial cushion, often doi: /bjaceaccp/mkm Continuing Education in Anaesthesia, Critical Care & Pain Volume 8 Number & The Board of Management and Trustees of the British Journal of Anaesthesia [2008]. All rights reserved. For Permissions, please journals.permissions@oxfordjournals.org associated with mitral regurgitation due to an anterior leaflet cleft. (iii) Sinus venosus ASD (5 15%) nearly always associated with anomalous pulmonary venous drainage. (iv) Unroofed coronary sinus. Of these, only an ostium secundum ASD is suitable for percutaneous closure. Presentation depends upon the magnitude of the left to right shunt. Effort dyspnoea is seen in 30% of patients by the third decade and more than 75% of patients by the fifth decade. 2 Atrial arrhythmias (atrial fibrillation and flutter) are common and are secondary to atrial dilatation. Clinical examination may reveal fixed splitting of the second heart sound coupled with a pulmonary flow murmur. The classically described electrocardiogram of an ASD is right bundle branch block (RBBB) and axis deviation (right for secundum and left for primum). There is good evidence that surgical shunt closure improves life expectancy, 3 especially if the shunt fraction is 1.7 or the pulmonary artery pressure is elevated. 3 Randomized trials comparing percutaneous closure with medical surveillance have not been performed because of ethical concerns, after the publication of these surgical data. A large non-randomized trial comparing surgical and percutaneous closure did demonstrate similar success without major complication (98.5% percutaneous vs 100% surgical, P. 0.05); however, the minor complication rate was higher in the surgical group (24.0% vs 7.2%, P, 0.001) and mean (SD) length of stay was also significantly prolonged [3.4 (1.2) days vs 1.0 (0.3) day]. There was no mortality in either group. Septal closure for cryptogenic stroke PFO is a very common defect caused by the failure of the thin primum and thick secundum septa to adhere at one edge of the fossa ovalis (Fig. 2). This failure of adherence creates a tunnel of variable length which permits

2 Closure of atrial septal defects Venous thrombosis is often presumed to have been present but may not be identified. Percutaneous PFO closure in this setting is associated with a significantly lower risk of further cerebrovascular events compared with medical therapy alone (7.3% vs 33.2%; P, 0.01). It is indicated in patients with two or more episodes of cryptogenic stroke. 6 Fig. 1 Ostium secundum ASD, seen on mid-oesophageal short axis view of aortic valve on TOE. communication between the two atria. In utero, this tunnel allows oxygenated blood from the placenta to pass from the right to the left atria, thus bypassing the lungs. After birth, the tunnel fails to close in up to 27% of the population, 4 but it usually acts as a flap valve resulting in minimal left to right flow. Right to left flow is also limited in adults because the left atrial pressure exceeds that of the right. However, under certain circumstances that transiently raise right above left atrial pressure (e.g. cough, sniff, release of abdominal straining, and valsalva manoeuvre), the flap valve can open (sometimes quite widely) and permit blood or clot to pass from the right to the left atria. Echocardiography is indicated after a recognized cerebral event (either transient or permanent). The presence of a PFO (or ASD), in the absence of other causative conditions, may prompt the presumptive diagnosis of paradoxical embolus. This should be based on the concomitant diagnosis of venous and arterial thrombosis and an abnormal connection between the venous and the arterial circulations. Owing to the anatomy of the aortic arch, arterial embolization is nearly always a cerebrovascular event (98%). 5 Septal closure for decompression illness The ambient increased pressures encountered during diving lead to super-saturation of tissues with nitrogen. During over-rapid ascent, the reduction in ambient pressure means that the tissue can no longer support such high concentrations of dissolved nitrogen and the gas comes out of solution to form bubbles, which may aggregate in the venous system. These bubbles are usually filtered by the lungs and thus prevented from causing systemic effects. The presence of an ASD or PFO can result in gas embolization to the arterial circulation and the development of neurological symptoms, known as decompression illness. 7,8 The discovery of an atrial septal defect during medical examination of divers and fighter pilots is an indication for closure before certification can be issued. Conversely, the defect may be diagnosed after recovery from an episode of decompression illness (the bends). Preoperative investigations Patients are commonly referred after the discovery of a defect on transthoracic echocardiography; if a small PFO is present, this may only have been demonstrated by a positive bubble test (air bubbles seen in both right and left atria) during a Valsalva manoeuvre. Preoperative TOE is obligatory to allow confirmation of the defect, accurate sizing, and determination of appropriateness for percutaneous closure. If the defect is very large (.3 cm) or complicated (associated with other abnormalities), or an incomplete rim is detected, referral for surgical closure is indicated. All patients should be warned of the possibility of procedure failure ( particularly in PFO closure where it may be technically impossible to pass a guidewire along the PFO tunnel) and informed about potential complications. Other appropriate investigations include ECG, coagulation studies (if on warfarin), full blood count, and blood biochemistry (if.60yr old or otherwise indicated). Choice of device Fig. 2 PFO, seen on mid-oesophageal bicaval view on TOE. There are a variety of devices available (Fig. 3), and all are relatively expensive (ranging from 2500 to 5000). The most established device for ASD closure is the Amplatzer w septal occluder. This is made from a double nitinol disk with a polyester coat. The nitinol (nickel titanium alloy) has the ability to return to its original conformation after deformation. This permits delivery of the device through a sheath and re-conformation across the ASD. This device is strong, self-centres in the ASD, and is easily recaptured and redeployed, although still attached to the delivery cable. Continuing Education in Anaesthesia, Critical Care & Pain j Volume 8 Number

3 Anaesthesia for percutaneous closure Alternatively, the HELEX septal occluder may be used; this is more suitable for the closure of smaller ASDs. PFO closure devices include the Premere which has a left atrial anchor and a right atrial disk, joined by a suture of variable length. Anaesthetic management Many centres now perform this procedure as a day case, producing considerable cost savings without increased patient risk. Anticoagulation or anti-platelet drugs should be stopped according to local guidelines. Significant pulmonary hypertension is an indication for overnight stay and other investigations such as right heart catheterization may be required. Such patients may become haemodynamically unstable during anaesthesia, and specialist attention and postoperative care may be required. The procedure is most commonly carried out in the catheter laboratory, where appropriate imaging equipment is located. TOE during the procedure is essential to: ensure appropriate placement of the closure device; prevent complications, for example, interference with other cardiac structures (most commonly pulmonary vein or mitral valve); allow detection of early thrombus; provide confirmation of device stability after placement. Fig. 3 Amplatzer w and HELEX septal occluder (designed for ASD closure) and Premere device (designed for PFO closure). Because the procedure must be carried out in the supine position with the TOE probe in situ, general anaesthesia with endotracheal intubation is required. The use of intracardiac echo (ICE) is emerging. The probe, which is single use only, is inserted into the femoral vein via a 10F catheter and advanced directly into the right atrium; it can provide 2D echo and colour flow Doppler. Where ICE is used, sedation may be sufficient. However, the probes are expensive and good quality imaging is difficult to acquire during the procedure, limiting uptake of the technology. A balanced anaesthetic technique with short-acting drugs is indicated; direct arterial pressure monitoring is reserved for highrisk cases. Muscle relaxation and endotracheal intubation is required and maintenance can be via an inhalation technique or total i.v. anaesthesia ( propofol + remifentanil). Nitrous oxide should be avoided because of the potential to increase intravascular bubble size. Antibiotic prophylaxis is required according to local guidelines (flucloxacillin and gentamicin or vancomycin if penicillin allergic is a suitable regime). Heparin (100 U kg 21 ) is administered to prevent early thrombus formation. Simple analgesics (e.g. acetaminophen) and anti-emetics may be administered intraoperatively. The patient should be monitored in an appropriate recovery area before discharge to the ward. 18 Continuing Education in Anaesthesia, Critical Care & Pain j Volume 8 Number

4 Closure of atrial septal defects prescribed for at least 6 months to reduce the potential for late thrombus formation, unless warfarin treatment is indicated for another condition. The patient can be discharged home according to local unit protocol. Follow-up echocardiography should be performed at 6 months to confirm septal closure and disappearance of trans-septal blood flow. Until this time (when endothelialization should be complete), antibiotic prophylaxis is recommended for all dental or invasive investigations or procedures. Complications Major complications include the following. Fig. 4 Fluoroscopy screening image of ASD device (both disks may be seen) after placement, still on delivery cable; TOE probe is also in situ. Placement of septal occlusion device Access is gained via the right femoral vein using a 9F sheath. A 6F multipurpose catheter is mounted on a soft J tipped guidewire and passed into the right atrium via the inferior vena cava. The wire is then passed across the atrial septum, guided by a combination of fluoroscopy at 208 left anterior oblique tilt and continuous observation of the TOE. This is generally straightforward with ASDs but can be more challenging with PFOs where a number of patient positioning manoeuvres and attempts may be required. If a PFO cannot be crossed, the procedure is abandoned. There is no indication for the formation of an iatrogenic atrial tract with a trans-septal needle. After guidewire placement, a larger sheath is advanced. The septal closure device is then loaded onto the applicator and inserted into the sheath; this is commonly performed under water to allow very careful de-airing. The device in its sheath is then advanced into the left atrium, and the first disk deployed by slowly advancing the device out of the sheath. This is then pulled back against the left side of the inter-atrial septum before the second disk is deployed on the right side by pulling back further on the delivery sheath (Fig. 4). The TOE is then used to confirm correct placement and stability, often by vigorous movement of the device during observation (the wiggle test). When stability has been confirmed and all cardiac structures have been examined, the device is deployed and the applicator removed. Postoperative care The patient should remain supine for up to 2 h until the venous sheath is removed. Aspirin and clopidrogel are commonly Air embolism: During deployment, air embolism can cause transient myocardial ischaemia, leading to ST changes on ECG; demonstrable regional wall movement abnormalities are seen on TOE. Intervention is not required, and cardiac function usually recovers spontaneously. Arrhythmias: Atrial fibrillation or flutter is relatively common during placement of the device due to atrial manipulation. It is self-limiting and rarely causes haemodynamic compromise; if still present at the end of the procedure, synchronized DC cardioversion should be attempted before cessation of anaesthesia. Thrombus formation on device or applicator: Full anticoagulation should be commenced immediately, and the patient admitted for close observation after operation. Careful neurological testing and monitoring should prompt immediate cerebral computerized tomography and neurosurgical referral if a new deficit is observed (this is very rare). Embolization of the device: This is extremely rare, provided the team is sufficiently experienced and TOE guidance is used. Pericardial haemorrhage and tamponade: This is caused by wire damage to a cardiac structure. A pericardial drainage catheter or sternotomy may be required if the bleeding is severe or continuous. A study of 3850 device closures reported no device-related deaths, a major complication rate of 0.3% (tamponade, stroke, myocardial infarction, device embolization, and major bleeding) and a minor complication in 2.8% of cases (arrhythmia, minor bleeding, and bruising). This is comparable with percutaneous coronary intervention. 9,10 References 1. Bedford D. The anatomical types of atrial septal defect. Their incidence and clinical diagnosis. Am J Cardiol 1960; 6: Campbell M. Natural history of atrial septal defect. Br Heart J 1970; 32: Continuing Education in Anaesthesia, Critical Care & Pain j Volume 8 Number

5 Anaesthesia for percutaneous closure 3. Konstantinides S, Geibel A, Olschewski M, et al. A comparison of surgical and medical therapy for atrial septal defect in adults. N Engl J Med 1995; 333: Hagen PT. Incidence and size of patent foramen ovale during the first 10 decades of life: an autopsy study of 965 normal hearts. Mayo Clin Proc 1984; 59: Brecker SJ. Percutaneous Device Closure of the Atrial Septum. Informa Healthcare, Windecker S, Wahl A, Nedeltchev K, et al. Comparison of medical treatment with percutaneous closure of patent foramen ovale in patients with cryptogenic stroke. J Am Coll Cardiol 2004; 44: Wilmhurst PT, Byrne JC, Webb-Peploe MM. Relationship between interatrial shunt and decompression illness in divers. Lancet 1989; ii: Wilmhurst PT, Pearson MJ, Walsh KP, Morrison WL. Relationship between right-to-left shunts and cutaneous decompression illness. Clin Sci 2001; 100: Omeish A, Hijazi ZM. Transcatheter closure of atrial septal defects in children & adults using the Amplatzer Septal Occluder. J Interv Cardiol 2001; 14: Spies C, Timmermanns I, Schräder R. Transcatheter closure of secundum atrial septal defects in adults with the Amplatzer septal occluder: intermediate and long-term results. Clin Res Cardiol 2007; 96: (Epub 26 February 2007) Please see multiple choice questions Continuing Education in Anaesthesia, Critical Care & Pain j Volume 8 Number