CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 2, March/April 2022 98 AFRICA Electrocardiogram manifestations of hyponatraemia Shi Zou, Qian Zhang, Shicheng Gao, Mingqi Luo, Xuedong Gan, Ke Liang Abstract Electrolytes play a vital role in myocardial electrophysiological activities in the human body. Electrolyte disturbances can affect depolarisation and repolarisation of myocardial cells and thus result in arrhythmia. The most common electrolyte disturbance among hospitalised patients is hyponatraemia. We report on a case of an acquired immune deficiency syndrome patient with decompensated cirrhosis, who developed sinus arrest from hyponatraemia. The electrocardiogram manifestations at different sodium concentrations were also recorded in subsequent therapeutic processes. Keywords: hyponatraemia, ECG, cirrhosis, sinus arrest Submitted 20/2/21, accepted 12/7/21 Published online 17/9/21 Cardiovasc J Afr 2022; 33: 98–100 www.cvja.co.za DOI: 10.5830/CVJA-2021-036 Hyponatraemia is generally defined as a serum sodium concentration lower than 135 mmol/l, which is associated with increased rates of mortality and morbidity.1,2 The clinical presentation may be highly variable, ranging from no symptoms to neurological symptoms such as confusion and coma, or even death.3 Although serum sodium concentration is known to be associated with arrhythmia,4,5 as far as we know, no study on the various manifestations of arrhythmia caused by different degrees of hyponatraemia has been published. In this case report, we recorded the case of an acquired immune deficiency syndrome (AIDS) patient with decompensated cirrhosis who developed sinus arrest due to hyponatraemia. The changes on electrocardiogram (ECG) at different serum sodium concentrations in subsequent therapeutic process were also documented. Case report A 50-year-old woman was admitted to our hospital on 2 December 2011 with complaints of abdominal distention for two weeks. She had a history of AIDS and chronic hepatitis C for seven years, and had no history of heart disease or hyponatraemia. The patient had been receiving antiretroviral therapy (combination of lamivudine, tenofovir and lopinavir/ ritonavir) for one year. She also received diuretic treatment (furosemide) for cirrhotic ascites. On admission, the patient was alert and orientated, and co-operated with the medical staff. On physical examination, the patient had mild sclerotic jaundice of the skin and sclera, and palmar erythema with grade 2 cirrhotic ascites. Cardiac and other system examinations revealed no abnormalities. Laboratory tests revealed a potassium concentration of 3.68 mmol/l (normal range: 3.5–5.5 mmol/l) and a sodium level of 137.4 mmol/l (normal: 132–146 mmol/l). Total bilirubin concentration was elevated to 83.4 µmol/l (normal: 5–21 µmol/l) and albumin level was reduced to 28.7 g/l (normal: 40–55 g/l). Blood urea nitrogen concentration was 8.97 mmol/l (normal: 2.8–7.6 mmol/l), creatinine level was 156.3 µmol/l (normal: 64–104 µmol/l) and the estimated glomerular filtration rate (eGFR) was 38 ml/min. Myocardial enzymes were normal. Abdominal ultrasound showed liver cirrhosis, portal hypertension, ascites and cholecystolithiasis. The ECG showed normal sinus rhythm on admission. After admission, diuretics (furosemide, spirolactone and hydrochlorothiazide) were started. On 14 December 2011, the patient showed symptoms including chest tightness, palpitation, headache, fatigue and drowsiness, and an ECG showed sinus arrest (the longest R-R interval was 3.8 seconds) and junctional escape beats (Fig. 1A). Electrolyte tests revealed severe hyponatraemia (102 mmol/l). The hyponatraemia was gradually corrected by intravenous 3% hypertonic saline.6 The patient’s symptoms were improved and the ECG showed various manifestations at different serum sodium concentrations (Fig. 1, Table 1). In the next few days, a 24-hour Holter recording showed sinus rhythm. Discussion To our knowledge, sinus arrest associated with hyponatraemia has not been reported in the literature. The pathogenesis of hyponatraemia-induced sinus arrest or cardiac conduction defects is yet to be elucidated, and data in the literature are scarce. According to the clinical observation, low extracellular sodium concentration may shorten the depolarisation of the Department of Infectious Diseases, Zhongnan Hospital, Wuhan University, Hubei, China Shi Zou, MD Shicheng Gao, MD Mingqi Luo, MD Ke Liang, PhD, keliang@whu.edu.cn Qingshan District Center for Disease Control and Prevention, Wuhan, China Qian Zhang, MD Department of Cardiology, Zhongnan Hospital, Wuhan University, Hubei, China Xuedong Gan, MD, dhgxd319@163.com Department of Nosocomial Infection Management; Center of Preventing Mother-to-Child Transmission for Infectious Diseases, Zhongnan Hospital, Wuhan University, Hubei; Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China Ke Liang, PhD
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