JAP  Volume 7 Issue 1 Case Report


Andersen-Tawil Syndrome: Anaesthetising around the body


of problems Such a rare disorder is poorly described in the medical literature and it can feel somewhat like shooting anaesthetics into the dark. Dr Will Packer and Dr Strätling describe the difficulties in treating an ATS patient, and add another nugget to the limited body of knowledge on this disorder.


ndersen-Tawil Syndrome (ATS) is a rare hereditary disorder (estimated: <1:1,000,000) of abnormal potassium channels. The autosomal dominant condition results in a triad of episodic flaccid muscle weakness, dysmorphic features and ventricular arrhythmias (commonly including long QT syndrome).1 The risk to ATS patients presenting for anaesthesia appears


A


significantly increased for five main reasons. Firstly, patients are at ultra-high risk of cardiac death or morbidity due to arrhythmia precipitated by increased sympathetic activity, electrolyte imbalances, hypovolaemia or QT-interval modulating drugs. Secondly, there is an increased probability of airway difficulties. Thirdly, there is considerable perioperative risk of respiratory failure due to attacks of episodic muscular weakness. Fourthly, there is a probable increased susceptibility to malignant hyperthermia, and finally, a high risk of drug treatment errors exists, as a large number of drugs commonly used in anaesthesia are contraindicated, as they trigger the above complications. Notably, QT-time interfering agents may trigger serious cardiac complications, which often show an overall refractoriness to anti- arrhythmic agents and treatment.2 The long list of relative or absolute drugs contraindications includes many commonly used emergency drugs, QT-prolonging drugs, K+


/Ca2+ /Mg2+ interacting compounds and muscle-affecting


agents, including: • Adrenaline, phenylephrine, ephedrine, metaraminol • Atropine, glycopyrolate, neostigmine • Amiodarone, other Class I and III compounds • Cocaine, other local anaesthetics if used in large volumes • Suxamethonium, non-depolarizing muscle relaxants • Volatile anaesthetics • Thiopentone, ketamine • Antihistamines, bronchodilators • Ondansetron, dexamethasone, prochlorperazine • Plus many others.3 Presented with a patient with ATS who was scheduled for elective surgery, our management plan was devised after much research into the condition, as currently there is very little literature about the disorder and hardly any guidance specifically on the anaesthetic and peri-operative management of these high risk patients. Management focuses on avoiding precipitants and pursuing alternative treatment options.


38 www.japractice.com


Case Report We report on a 41-year-old female patient, who presented for


elective arthroscopic capsular release of her left shoulder. Physical examination revealed a slim lady (BMI 20) with Mallampatti score three and small enoral space. ECG showed multiple ventricular extrasytoles and a QT interval of 414ms (though on prior ECGs was up to 580ms.) Echocardiogram showed a small patent foramen ovale with normal ventricles, heart valves and ejection fraction. Clinically, the patient had regular palpitations from ventricular ectopics but had been free of runs of ventricular tachycardia and had been stable on the beta-blocker nadolol for many months. The full blood count revealed a mild anaemia and potassium, calcium


“Drugs that may have a beneficial effect on cardiac function may worsen skeletal muscle function, creating a unique treatment challenge”


and magnesium levels were within the normal range. Prior to starting the anaesthetic, staff members were briefed about her condition and a written peri-operative management plan covering foreseeable adverse events was provided. Nadalol was continued in the perioperative period to help reduce


sympathetic stimulation and maintain the QT interval. Despite the potential risk of aggravating post-operative muscular weakness, a pre-medication with midazolam was considered and offered but was declined by the patient. Quiet surroundings were provided. In addition to standard monitoring, invasive arterial monitoring


was cited and defibrillator gel pads were applied to the chest and attached to a defibrillator with a transcutaneous pacing facility. It was ensured that a consultant cardiologist was present in the hospital and pacing wire equipment was available. Difficult airway equipment was on standby. Andersen-Tawil Syndrome is associated with channelopathies such as hypokalaemic periodic paralysis and therefore the patient was considered more susceptible to malignant hyperthermia (MH).4


Dantrolene stock was checked before starting and standard


precautions were taken as for MH susceptible patients to provide a trigger-free anaesthetic.


Induction included a pre-load of Hartmann’s 500ml followed by


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44