(P110) Primary Carnitine Deficiency and Wolf-parkinson-white Syndrome – a Case Report

Chief Complaint : A 12-year-old girl was brought by the emergency medical services with the complaint of choking followed by difficulty breathing, seizure, and loss of consciousness.

History of Present Illness : She had been eating watermelon, suddenly choked with difficulty breathing, developed a generalized tonic-clonic seizure, and lost consciousness. When EMS arrived, she was found to be in cardiac arrest with ventricular fibrillation. EMS placed a laryngeal tube (LT), had two rounds of defibrillation, and on arrival to ED she had a return of spontaneous circulation (ROSC). The patient is a known case of Primary Carnitine Deficiency.

Pertinent Physical Exam: Her respiratory rate was 20 breaths per minute, oxygen saturation was 97% on room air, blood pressure was 115/65, heart rate was 94 beats per minute, and temperature was 37 degrees Centigrade. Her weight and height are both above the 97th centile. There was no stridor and chest auscultation revealed bilateral diffuse crepitations but no wheeze. She had warm extremities, and capillary refill time < 2 seconds. Her pupils were 4 mm, equal, and reactive to light. Her Glasgow Coma Scale was no opening of eyes to any stimulus (E1), decerebrate response to a painful stimulus (M1), and intubated (Vt).

Pertinent Laboratory Data: Hemoglobin, white blood cell, coagulation profile (INR), glucose, blood gas, creatinine, and electrolytes are normal. She has mildly raised transaminases. The initial electrocardiogram showed findings of Wolf Parkinson White Syndrome.
Echocardiogram showed good contracting heart with no pericardial effusion, no obvious segmental wall motion abnormality, and no right ventricular dilation, or D-sign. CT head was normal and CTPA showed bilateral ground glass opacities and consolidation suggestive of aspiration, no foreign body with no vessel filling defect. Magnetic resonance imaging of the brain showed evolving ischemia/edema, suggestive of metabolic decompensation due to the reduction or absence of beta-oxidation of fatty acids.

Case Discussion: The catecholamine surge in sudden hypoxia due to choking contributes to arrhythmias and excitation of cardiac tissue due to late sodium current producing a new heartbeat when the heart has not recovered from previous electrical activity [1]. In the presence of an accessory pathway in WPW syndrome, excitation can degenerate into fatal arrhythmias. The accessory pathway can conduct electrical current, either antegrade, retrograde, or both. The characteristic electrocardiographic (ECG) signs are short PR interval (less than 120 milliseconds), slurred QRS (known as delta wave), and prolonged QRS complex (more than 120 milliseconds) [2]. In this case, a sudden episode of choking led to hypoxia which shifted the metabolic pathway from aerobic to anaerobic. Since the patient is deficient in carnitine, it also worsened the production of energy by beta-oxidation of fatty acids which is an alternative pathway for generating ATP (adenosine triphosphate).
Ventricular fibrillation (VF) is considered one of the favorable factors for neurologic outcome [3]; However, 30-80% can have anoxic encephalopathy depending upon the timing of the first defibrillation [4], which was delayed in this case. PCD is found to be associated with short QT intervals and ventricular arrhythmias including ventricular fibrillation and ventricular tachycardia [5] but underlying cardiomyopathy is evident on echocardiography and rapidly reversed on replenishing carnitine [6,7]. The absence of cardiomyopathy and the presence of WPW syndrome are two unique features related to this case. The co-existence or association of primary carnitine deficiency with Wolf-Parkinson-White syndrome is subject to further exploration and research as fatal dysrhythmias can result. The available literature is insufficient to address this relation or association.

References and Acknowledgements (Optional): 1. Plant LD, Xiong D, Romero J, et al.: Hypoxia produces pro-arrhythmic late sodium current in cardiac myocytes by SUMOylation of NaV1.5 channels. Cell Reports. 2020, 30:2225-2236. 10.1016/j.celrep.2020.01.025
2. Sidhu J, Roberts R: Genetic basis and pathogenesis of familial WPW syndrome. Indian Pacing Electrophysiology Journal. 2003, 3:197-201.
3. Kim YJ, Ahn S, Sohn CH, et al.: Long-term neurological outcomes in patients after out-of-hospital cardiac arrest. Resuscitation. 2016, 101:1-5. 10.1016/j.resuscitation.2016.01.004
4. Mateen FJ, Josephs KA, Trenerry MR, et al.: Long-term cognitive outcomes following out-of-hospital cardiac arrest: a population-based study. Neurology. 2011, 77:1438-1445. 10.1212/WNL.0b013e318232ab33
5. Fu L, Huang M, Chen S: Primary carnitine deficiency and cardiomyopathy. Korean Circulation Journal. 2013, 43:785-792. 10.4070/kcj.2013.43.12.785
6. Roussel J, Labarthe F, Thireau J, et al.: Carnitine deficiency induces a short QT syndrome. Heart Rhythm. 2016, 13:165-174. 10.1016/j.hrthm.2015.07.027
7. Tomlinson S, Atherton J, Prasad S: Primary carnitine deficiency: A rare, reversible metabolic cardiomyopathy. Case Reports in Cardiology. 20182018, 3232105-2018. 10.1155/2018/3232105