Anaesthetic management of a patient with complex, cyanotic congenitally corrected transposition of great arteries for electrophysiological study and thermoablation

Abstract

Congenitally corrected transposition of great arteries (ccTGA) is a rare congenital heart disease, and little literature is available that describes its anaesthetic management. We present the perioperative management of a patient with complex, cyanotic ccTGA who underwent electrophysiological study with catheter ablation under general anaesthesia. Good understanding of the patient’s complex cardiac anatomy and physiology and multidisciplinary communication are vital to facilitate the successful care of the patient.

Background

Congenital heart disease is a common class of major congenital malformations, with a worldwide prevalence of approximately 8:1000 of all live births.^{1 2} With advances in antenatal screening, congenital heart diseases are detected early in pregnancy.³ Coupled with readily available child health screening, it is uncommon to have untreated congenital heart diseases presenting in adulthood. We present a case of complex congenital cardiac disease presenting in adulthood coming for a procedure and discuss the anaesthetic implications.

Case presentation

A 38-year-old New York Heart Association class 2 female who weighed 51 kg and was 162 cm tall was diagnosed with dextrocardia at birth but was not followed up. She developed palpitations and was admitted to the hospital for syncope 6 years ago. She subsequently had one admission for a cardioembolic stroke and multiple admissions for malignant arrhythmias like unstable supraventricular tachycardia (SVT), atrial fibrillation (AF) and atrioventricular nodal re-entrant tachycardias (AVNRTs). Despite medical therapy, her symptoms worsened and she finally agreed to undergo an electrophysiological study and ablation of malignant conduction pathways. Her medications included sotalol 40 mg two times per day, bisoprolol 1.25 mg two times per day and apixiban 2.5 mg two times per day for the medical management of her AF. Her heart rate was 67 beats/min and her blood pressure was 93/59 mm Hg. She had dual heart sounds with a soft pan systolic murmur on auscultation, and her breath sounds were vesicular with no bibasal crackles. Her cardiorespiratory examination did not elicit any signs of acute heart failure. Her room air oxygen saturation was 82%. There was no anticipated difficulty in airway management.

Investigations

Her most recent (figure 1) and earliest ECGs showed normal sinus rhythm, but previous ECGs showed AF and AVNRT. Her transthoracic echocardiography reported dextrocardia with pulmonary atresia, total anomalous pulmonary venous drainage (TAPVD) with an enlarged common TAPVD chamber on the left side of the chest and congenitally corrected transposition of great arteries (ccTGA). There was a 27 mm ventricular septal defect (VSD) and 38 mm atrial septal defect, both with bidirectional shunting. The left ventricular ejection fraction was 47% and the right ventricular fractional area change was 44%. A more recent cardiac MRI demonstrated pulmonary atresia with multiple major aortopulmonary collateral arteries arising from the descending thoracic aorta and the left subclavian artery, and drainage of the TAPVD into a 6 cm anomalous vein that empties into a large dilated pulmonary venous chamber at the superior aspect of the left-sided atrium. In addition, a CT angiography (figure 2) also reported a persistent left superior vena cava (SVC) emptying into the pulmonary venous chamber, with a bridging vein connecting both SVCs (figure 3).

Figure 1.

Most recent ECG before ablation.

Figure 2.

Top left: major aortopulmonary collateral artery to the right and left lungs. Top right: TAPVD common venous chamber and 2/4 pulmonary veins draining to the common chamber. Bottom left. Ventricular septal defect (green arrow) and atrial septal defect with common atrium (red). Bottom right: widely patent TAPVD outlet. TAPVD, total anomalous pulmonary venous drainage.

Figure 3.

Schematic diagram of the patient’s cardiac anatomy, illustrated by J Chen. ccTGA, ongenitally corrected transposition of great arteries; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; SVC, superior vena cava; TAPVD, total anomalous pulmonary venous drainage.

Treatment

On the day of the procedure, a multidisciplinary meeting involving the anaesthetic team, cardiologists and echocardiologists was held to discuss the details of the procedure and potential complications. Her antiarrhythmic medications were suspended on the morning of the procedure to allow better detection and mapping of malignant pathways. Vancomycin 1 g was given 1 hour prior to the procedure. Fasting was minimised to ensure euvolaemia. Standard American Society of Anaesthesiology monitoring was used and a right radial arterial cannula was inserted for beat-to-beat blood pressure monitoring. A left subclavian central venous catheter was inserted due to uncertainty of the bilateral drainage of the internal jugular veins into the SVC. Defibrillation pads were applied prior to induction.

Induction was performed with 1 mg midazolam, 10 mg etomidate and 50 mg rocuronium. Lignocaine (50 mg) and fentanyl (100 mcg)were also given to obtund the sympathetic response during laryngoscopy. A size 7 endotracheal tube was inserted with a McGrath videolaryngoscope after a first direct laryngoscopy attempt, revealing a Cormack and Lehane grade III view. The Patient was ventilated at a tidal volume of 400 mL, PEEP of 5 cmH₂O, frequency of 12, targeting an end-tidal carbon dioxide concentration between 35 mm Hg and 40 mm Hg. The oxygen saturation was 98% during preoxygenation and was kept above 94% during the procedure. A remifentanil infusion was titrated between 0.03 mcg/kg/min and 0.1 mcg/kg/min, and the desflurane concentration was kept between 5.0% and 6.0%. Intra-arterial monitoring was used and a mean arterial pressure of at least 65 mm Hg was targetted. A conservative fluid management strategy was adopted, and a total of 750 mL of Hartmann’s solution was given over 4 hours. Heparin was administered repeatedly by the cardiologist, targeting an activated clotting time of 250–350 s.

The initial mapping triggered an SVT, causing a 5 s drop in cardiac output as seen by the fall in the arterial blood pressure. The blood pressure returned to normal when the stimulus was discontinued. Four episodes of prolonged atrial flutter with 2:1 and 3:1 conduction developed during subsequent mappings and adenosine boluses of 6–12 mg were given when the arrhythmias did not terminate after cessation of the stimulus. These allowed mapping of both right and left atria, which confirmed the presence of a biatrial tachycardia, with no particular area of slow conduction. Boluses of ephedrine of 5 mg were given intermittently up to 20 mg, and an ephedrine infusion of 10 mg/hour was later started, targeting a mean arterial pressure above 65 mm Hg. Thermoablation of the purported cavotricuspid isthmus was performed over an area that showed decremental conduction during initiation of the tachycardia. This was successful, demonstrated by a bidirectional block during mapping and no further inducible atrial dysrhythmias during stimulation.

An arterial blood gas performed at the end of the procedure showing no abnormalities. Sugammadex of 100 mg was given and the patient was extubated. The oxygen saturation remained about 90%–95% on room air. An additional 25 mcg fentanyl and 1 g paracetamol was given for analgesia postprocedure. Ephedrine infusion was stopped at the end of the procedure, and no further doses of vasopressors were required.

Outcome and follow-up

The patient was discharged to the coronary care unit (CCU) for telemetry and haemodynamic monitoring and to the general ward next day. During her 1-year follow-up, she experienced palpitations once every few months, but these spontaneously resolved.

Discussion

ccTGA is a result of embryonic malrotation of atria, ventricles and great vessels, resulting in atriaventricular and ventriculoarterial discordance.⁴ The right atrium connects to the left ventricle (LV), leading to the pulmonary arteries. The left atrium connects to the right ventricle (RV), leading to the aorta. ccTGA can be associated with other structural and conduction abnormalities,^{4 5} such as VSDs, LV outflow tract obstruction from subpulmonary stenosis, pulmonary stenosis or atresia and abnormalities of the tricuspid valve. Preoperative evaluation with echocardiography or imaging with CT or MRI helps to identify these structural defects and associated abnormalities. When left untreated, patients may develop RV failure by the age of 45.⁵ Assessment of effort tolerance helps to evaluate the cardiac function and reserve.⁶

They are also at increased risk of developing complete heart blocks, as well as tachyarrhythmias from re-entrant circuits of abnormal conduction systems and accessory pathways. Atrial and ventricular tachycardias are also possible due to ventricular dysfunction and fibrosis. Symptoms such as syncope, dyspnoea or palpitations suggest the likelihood of such complications, and ECG or Holter reports should be reviewed.

Currently, limited literature is available about anaesthetic management for ccTGA. There are case reports where general anaesthesia or regional anaesthesia has been safely performed for patients with ccTGA under invasive monitoring, with availability of vasopressors and inotropes.^7–10 We chose a general anaesthesia technique to allow for optimal conditions to facilitate the procedure while being able to take control of ventilation and PaCO₂. Our goals were to minimise haemodynamic disturbances, minimise right-to-left shunts⁶ and avoid arrhythmias.

In our patient who had a large unrestricted shunt, there is inevitable mixing of oxygenated and deoxygenated blood; thus, the main goal would be to optimise the oxygen saturation of the arterial blood. Reducing pulmonary vascular resistance (PVR) will improve flow in the pulmonary circulation and return to the left atrium, possibly increasing the oxygen saturation of the mixed blood. Factors that increase PVR,^{1 2} such as hypoxia, hypercapnia, hypothermia, acidosis and sympathetic stimulation, must be aggressively controlled to improve pulmonary blood flow. It is also important to maintain an adequate perfusion pressure as blood flow to the lungs is now dependent on the mean arterial pressure. However, a balance between pulmonary and systemic blood flows must be achieved as overcirculation of the pulmonary circulation can also result in cardiac failure.¹¹

Maintenance of sinus rhythm provides an ‘atrial kick’ that contributes to 20%–30% of ventricular volume,¹² thus increasing the LV preload (our patient’s morphological RV). During mapping, the induced tachyarrhythmias can either cause a lack of synchronisation between atrial and ventricular contractions, losing the atrial kick, or reduce ventricular diastolic time, which is important for LV filling. Our patient tolerated such arrhythmias poorly, with rapid decreases of the blood pressure to 50–60 mm Hg systolic. Close communication should be maintained with the cardiologist to terminate any prolonged arrhythmias resulting in haemodynamic instability. If the arrhythmias persist, it should be treated either pharmacologically or by cardioversion. Preload should be maintained and the patient kept euvolaemic. Overzealous fluid administration must also be avoided to prevent cardiac failure.

Due to the complex anatomy of this patient, central venous access was challenging. The femoral sites would be used by the cardiologists for the procedure. After discussing with the cardiologists, the left subclavian vein was chosen as it was known from the scans to drain into the right SVC and back to the right atrium and was thought to be less likely to be inserted through the bridging vein. Cannulation of the jugular veins could lead to the left SVC, either directly or through the bridging vein, leading to potential complications such as arrhythmias.¹³

The American College of Cardiology/American Heart Association guidelines of 2017 recommend antibiotic prophylaxis for unrepaired cyanotic congenital heart disease, including palliative shunts and conduits.¹⁴ Current evidence also recommends for appropriate administration of preincision antimicrobials with discontinuation within 24 hours after skin closure for electrophysiology procedures.¹⁵

Catheter ablations are done in a catheterisation laboratory equipped with catheter navigation systems to map out the arrhythmic pathways. Irrigation fluids are used to cool the ablation catheters,¹⁶ which further emphasises the need for judicious fluid management especially in prolonged procedures to prevent fluid overload. Defibrillator pads should also be applied before the procedure in case cardioversion is required to terminate malignant arrhythmias.¹⁶ Considerations of providing anaesthesia in a remote site should apply.

Extra attention should be paid to patient positioning to reduce complications such as pressure sores or nerve injuries, as these procedures can be complicated and take time.⁶ Lines and monitoring cables should be neatly arranged so that they do not interfere with the procedure or imaging, or get dislodged during movement or transfer. Active and passive warming should be used with heat–moisture exchangers, forced air blankets and/or fluid warmers, and patient exposure minimised to reduce heat loss from convection and radiation.

Complications from cardiac catheterisations range from vascular related complications like bleeding, haematoma and vascular injury to cardiac perforations, complete heart blocks requiring pacemaker placements and haemodynamically unstable tachyarrhythmias requiring cardioversion.¹⁶ If any of such complications occur, appropriate monitoring must be provided postprocedure, and the disposition of the patient must be carefully decided. We sent our patient to the CCU due to the complex cardiac comorbidities and frequent haemodynamically unstable arrhythmias during the procedure.

Due to the limited literature available on anaesthetic management of ccTGA, considerations should be focused on ensuring haemodynamic stability by minimising arrhythmias and optimising ventricular function, as well as to minimise common mixing from intracardiac shunts. This can be achieved by having a detailed understanding of the patient’s complex cardiac lesions and pathophysiology, good multidisciplinary communication to optimise the patient’s comorbidities, and identify and manage potential perioperative complications.

Learning points.

• For patients with complex congenital cardiac lesions, good knowledge of the patient anatomy and pathophysiology is important. This is by thorough clinical assessment and rigorous screening of imaging and investigations previously done.

• A multidisciplinary approach where there is open communication among relevant stakeholders throughout the procedure facilitates anaesthetic planning and minimises the risk of developing complications or adverse events.

• Anaesthetic considerations of a remote site apply in the electrophysiological laboratories, and adequate preparation of equipment is vital.

• An understanding of the catheter ablation procedure is required to provide safe anaesthesia and to increase vigilance of the possible complications that may arise.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s).