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Tse G, Li KHC, Cheung CKY, Letsas KP, Bhardwaj A, Sawant AC, Liu T, Yan GX, Zhang H, Jeevaratnam K, Sayed N, Cheng SH, Wong WT. Arrhythmogenic Mechanisms in Hypokalaemia: Insights From Pre-clinical Models. Front Cardiovasc Med 2021; 8:620539. [PMID: 33614751 PMCID: PMC7887296 DOI: 10.3389/fcvm.2021.620539] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 01/13/2021] [Indexed: 12/21/2022] Open
Abstract
Potassium is the predominant intracellular cation, with its extracellular concentrations maintained between 3. 5 and 5 mM. Among the different potassium disorders, hypokalaemia is a common clinical condition that increases the risk of life-threatening ventricular arrhythmias. This review aims to consolidate pre-clinical findings on the electrophysiological mechanisms underlying hypokalaemia-induced arrhythmogenicity. Both triggers and substrates are required for the induction and maintenance of ventricular arrhythmias. Triggered activity can arise from either early afterdepolarizations (EADs) or delayed afterdepolarizations (DADs). Action potential duration (APD) prolongation can predispose to EADs, whereas intracellular Ca2+ overload can cause both EADs and DADs. Substrates on the other hand can either be static or dynamic. Static substrates include action potential triangulation, non-uniform APD prolongation, abnormal transmural repolarization gradients, reduced conduction velocity (CV), shortened effective refractory period (ERP), reduced excitation wavelength (CV × ERP) and increased critical intervals for re-excitation (APD-ERP). In contrast, dynamic substrates comprise increased amplitude of APD alternans, steeper APD restitution gradients, transient reversal of transmural repolarization gradients and impaired depolarization-repolarization coupling. The following review article will summarize the molecular mechanisms that generate these electrophysiological abnormalities and subsequent arrhythmogenesis.
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Affiliation(s)
- Gary Tse
- Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin, China.,Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Ka Hou Christien Li
- Faculty of Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - Konstantinos P Letsas
- Second Department of Cardiology, Laboratory of Cardiac Electrophysiology, Evangelismos General Hospital of Athens, Athens, Greece
| | - Aishwarya Bhardwaj
- Division of Cardiology, Department of Internal Medicine, State University of New York at Buffalo, Buffalo, NY, United States
| | - Abhishek C Sawant
- Division of Cardiology, Department of Internal Medicine, State University of New York at Buffalo, Buffalo, NY, United States
| | - Tong Liu
- Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin, China
| | - Gan-Xin Yan
- Lankenau Institute for Medical Research and Lankenau Medical Center, Wynnewood, PA, United States
| | - Henggui Zhang
- School of Physics and Astronomy, The University of Manchester, Manchester, United Kingdom
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Nazish Sayed
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States.,Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, United States.,Department of Medicine, Division of Cardiology, Stanford University School of Medicine, Stanford, CA, United States
| | - Shuk Han Cheng
- Department of Biomedical Sciences, College of Veterinary Medicine and Life Science, City University of Hong Kong, Hong Kong, China.,State Key Laboratory of Marine Pollution (SKLMP), City University of Hong Kong, Hong Kong, China.,Department of Materials Science and Engineering, College of Science and Engineering, City University of Hong Kong, Hong Kong, China
| | - Wing Tak Wong
- School of Life Sciences, Chinese University of Hong Kong, Hong Kong, China
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Uluganyan M, Ekmekçi A, Murat A, Avşar Ş, Ulutaş TK, Uyarel H, Bozbay M, Çiçek G, Karaca G, Eren M. Admission serum potassium level is associated with in-hospital and long-term mortality in ST-elevation myocardial infarction. Anatol J Cardiol 2016; 16:10-5. [PMID: 26467357 PMCID: PMC5336698 DOI: 10.5152/akd.2015.5706] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/09/2015] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE Current guidelines recommend a serum potassium (sK) level of 4.0-5.0 mmol/L in acute myocardial infarction patients. Recent trials have demonstrated an increased mortality rate with an sK level of>4.5 mmol/L. The aim of this study was to figure out the relation between admission sK level and in-hospital and long-term mortality and ventricular arrhythmias. METHODS Retrospectively, 611 patients with ST-elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention were recruited. Admission sK levels were categorized accordingly: <3.5, 3.5-<4, 4-<4.5, 4.5-<5, and ≥5 mmol/L. RESULTS The lowest in-hospital and long-term mortality occurred in patients with sK levels of 3.5 to <4 mmol/L. The long-term mortality risk increased for admission sK levels of >4.5 mmol/L [odds ratio (OR), 1.58; 95% confidence interval (CI) 0.42-5.9 and OR, 2.27; 95% CI 0.44-11.5 for sK levels of 4.5-<5 mmol/L and ≥5 mmol/L, respectively]. At sK levels <3 mmol/L and ≥5 mmol/L, the incidence of ventricular arrhythmias was higher (p=0.019). CONCLUSION Admission sK level of >4.5 mmol/L was associated with increased long-term mortality in STEMI. A significant relation was found between sK level of <3 mmol/L and ≥5 mmol/L and ventricular arrhythmias.
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Affiliation(s)
- Mahmut Uluganyan
- Clinic of Cardiology, Kadirli Government Hospital; Osmaniye-Turkey.
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Gabutti L, Salvadé I, Lucchini B, Soldini D, Burnier M. Haemodynamic consequences of changing potassium concentrations in haemodialysis fluids. BMC Nephrol 2011; 12:14. [PMID: 21470404 PMCID: PMC3079606 DOI: 10.1186/1471-2369-12-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 04/06/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A rapid decrease of serum potassium concentrations during haemodialysis produces a significant increase in blood pressure parameters at the end of the session, even if effects on intra-dialysis pressure are not seen. Paradoxically, in animal models potassium is a vasodilator and decreases myocardial contractility. The purpose of this trial is to study the precise haemodynamic consequences induced by acute changes in potassium concentration during haemodialysis. METHODS In 24 patients, 288 dialysis sessions, using a randomised single blind crossover design, we compared six dialysate sequences with different potassium profiles. The dialysis sessions were divided into 3 tertiles, casually modulating potassium concentration in the dialysate between the value normally used K and the two cut-off points K+1 and K-1 mmol/l. Haemodynamics were evaluated in a non-invasive manner using a finger beat-to-beat monitor. RESULTS Comparing K-1 and K+1, differences were found within the tertiles regarding systolic (+5.3, +6.6, +2.3 mmHg, p < 0.05, < 0.05, ns) and mean blood pressure (+4.3, +6.4, -0.5 mmHg, p < 0.01, < 0.01, ns), as well as peripheral resistance (+212, +253, -4 dyne.sec.cm-5, p < 0.05, < 0.05, ns). The stroke volume showed a non-statistically-significant inverse trend (-3.1, -5.2, -0.2 ml). 18 hypotension episodes were recorded during the course of the study. 72% with K-1, 11% with K and 17% with K+1 (p < 0.01 for comparison K-1 vs. K and K-1 vs. K+1). CONCLUSIONS A rapid decrease in the concentration of serum potassium during the initial stage of the dialysis-obtained by reducing the concentration of potassium in the dialysate-translated into a decrease of systolic and mean blood pressure mediated by a decrease in peripheral resistance. The risk of intra-dialysis hypotension inversely correlates to the potassium concentration in the dialysate. TRIAL REGISTRATION NUMBER NCT01224314.
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Affiliation(s)
- Luca Gabutti
- Division of Nephrology, Ospedale Carità, Via Ospedale, 6600 Locarno, Switzerland.
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Bowling CB, Pitt B, Ahmed MI, Aban IB, Sanders PW, Mujib M, Campbell RC, Love TE, Aronow WS, Allman RM, Bakris GL, Ahmed A. Hypokalemia and outcomes in patients with chronic heart failure and chronic kidney disease: findings from propensity-matched studies. Circ Heart Fail 2010; 3:253-60. [PMID: 20103777 DOI: 10.1161/circheartfailure.109.899526] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Little is known about the effects of hypokalemia on outcomes in patients with chronic heart failure (HF) and chronic kidney disease. METHODS AND RESULTS Of the 7788 patients with chronic HF in the Digitalis Investigation Group trial, 2793 had chronic kidney disease, defined as estimated glomerular filtration rate <60 mL/min per 1.73 m(2). Of these, 527 had hypokalemia (serum potassium <4 mEq/L; mild) and 2266 had normokalemia (4 to 4.9 mEq/L). Propensity scores for hypokalemia were used to assemble a balanced cohort of 522 pairs of patients with hypokalemia and normokalemia. All-cause mortality occurred in 48% and 36% of patients with hypokalemia and normokalemia, respectively, during 57 months of follow-up (matched hazard ratio when hypokalemia was compared with normokalemia, 1.56; 95% CI, 1.25 to 1.95; P<0.0001). Matched hazard ratios (95% CIs) for cardiovascular and HF mortalities and all-cause, cardiovascular, and HF hospitalizations were 1.65 (1.29 to 2.11; P<0.0001), 1.82 (1.28 to 2.57; P<0.0001), 1.16 (1.00 to 1.35; P=0.036), 1.27 (1.08 to 1.50; P=0.004), and 1.29 (1.05 to 1.58; P=0.014), respectively. Among 453 pairs of balanced patients with HF and chronic kidney disease, all-cause mortality occurred in 47% and 38% of patients with mild hypokalemia (3.5 to 3.9 mEq/L) and normokalemia, respectively (matched hazard ratio, 1.31; 95% CI, 1.03 to 1.66; P=0.027). Among 169 pairs of balanced patients with estimated glomerular filtration rate <45 mL/min per 1.73 m(2), all-cause mortality occurred in 57% and 47% of patients with hypokalemia (<4 mEq/L; mild) and normokalemia, respectively (matched hazard ratio, 1.53; 95% CI, 1.07 to 2.19; P=0.020). CONCLUSIONS In patients with HF and chronic kidney disease, hypokalemia (serum potassium <4 mEq/L) is common and associated with increased mortality and hospitalization.
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Ahmed A, Zannad F, Love TE, Tallaj J, Gheorghiade M, Ekundayo OJ, Pitt B. A propensity-matched study of the association of low serum potassium levels and mortality in chronic heart failure. Eur Heart J 2007; 28:1334-43. [PMID: 17537738 PMCID: PMC2771161 DOI: 10.1093/eurheartj/ehm091] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS Potassium homeostasis is essential for normal myocardial function, and low serum potassium may cause fatal arrhythmias. However, the association of low potassium and long-term mortality and morbidity in heart failure (HF) is largely unknown. METHODS AND RESULTS We studied 6845 HF patients in the Digitalis Investigation Group trial with serum potassium levels < or =5.5 mEq/L. Of these, 1189 had low potassium (<4 mEq/L). Propensity scores for low potassium were calculated for each patient and were used to match 1187 low-potassium patients with 1187 normal-potassium (4-5.5 mEq/L) patients. Effects of low potassium on outcomes were assessed using matched Cox regression analyses. All-cause mortality occurred in 379 (rate, 1103/10 000 person-years) normal-potassium and 441 (rate, 1330/10 000 person-years) low-potassium patients, respectively, during 3437 and 3315 years of follow-up [hazard ratio (HR), 1.25; 95% confidence interval (CI), 1.07-1.46; P = 0.006]. Cardiovascular mortality occurred in 297 (864/10 000 person-years) normal-potassium and 356 (1074/10 000 person-years) low-potassium patients (HR, 1.27; 95% CI, 1.06-1.51; P = 0.009). Cardiovascular hospitalization occurred in 610 (rate, 2553/10 000 person-years) normal-potassium and 637 (rate, 2855/10 000 person-years) low-potassium patients (HR, 1.13; 95% CI, 0.99-1.29; P = 0.082). CONCLUSION In a cohort of ambulatory chronic systolic and diastolic HF patients who were balanced in all measured baseline covariates, serum potassium <4 mEq/L was associated with increased mortality, with a trend towards increased hospitalization.
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Affiliation(s)
- Ali Ahmed
- Department of Medicine, University of Alabama at Birmingham, 1530 Third Avenue South, Birmingham, AL 35294-2041, USA.
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Abstract
Potassium depletion (KD) is a very common clinical entity often associated with adverse cardiac effects. KD is generally considered to reduce muscular Na-K-ATPase density and secondarily reduce K uptake capacity. In KD rats we evaluated myocardial Na-K-ATPase density, ion content, and myocardial K reuptake. KD for 2 wk reduced plasma K to 1.8 +/- 0.1 vs. 3.5 +/- 0.2 mM in controls (P < 0.01, n = 7), myocardial K to 80 +/- 1 vs. 86 +/- 1 micromol/g wet wt (P < 0.05, n = 7), increased Mg, and induced a tendency to increased Na. Myocardial Na-K-ATPase alpha(2)-subunit abundance was reduced by approximately 30%, whereas increases in alpha(1)- and K-dependent pNPPase activity of 24% (n = 6) and 13% (n = 6), respectively, were seen. This indicates an overall upregulation of the myocardial Na-K pump pool. KD rats tolerated a higher intravenous KCl dose. KCl infusion until animals died increased myocardial K by 34% in KD rats and 18% in controls (P < 0.05, n = 6 for both) but did not induce different net K uptake rates between groups. However, clamping plasma K at approximately 5.5 mM by KCl infusion caused a higher net K uptake rate in KD rats (0.22 +/- 0.04 vs. 0.10 +/- 0.03 micromol x g wet wt(-1) x min(-1); P < 0.05, n = 8). In conclusion, a minor KD-induced decrease in myocardial K increased Na-K pump density and in vivo increased K tolerance and net myocardial K uptake rate during K repletion. Thus the heart is protected from major K losses and accumulates considerable amounts of K during exposure to high plasma K. This is of clinical interest, because a therapeutically induced rise in myocardial K may affect contractility and impulse generation-propagation and may attenuate increased myocardial Na, the hallmark of heart failure.
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Affiliation(s)
- Henning Bundgaard
- Medical Department B 2142, Heart Centre, Rigshospitalet, National University Hospital, University of Copenhagen, 2100 Copenhagen, Denmark.
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